Effects of various mixed salt-alkaline stresses on growth, photosynthesis,

Nutrient removal in an A2O-MBR reactor with sludgereductionABSTRACTIn the present study, an advanced sewage treatment process has been developed by incorporating excess sludge reduction and phosphorous recovery in an A2O-MBR process. The A2O-MBR reactor was operated at a flux of 77 LMH over a period of 270 days. The designed flux was increased stepwise over a period of two weeks. The reactor was operated at two different MLSS range. Thermo chemical digestion of sludge was carried out at a fixed pH (11)and temperature (75℃) for 25% COD solubilisation. The released pbospborous was recovered by precipitation process and the organics was sent back to anoxic tank. The sludge digestion did not have any impact on COD and TP removal efficiency of the reactor. During the 270 days of reactor operation, the MBR maintained relatively constant transmembrane pressure. The results based on the study indicated that the proposed process configuration has potential to reduce the excess sludge production as well as it didn't detonated the treated water quality.Keywords: A2O reactor; MBR; Nutrient removal; TMP1. IntroductionExcess sludge reduction and nutrients removal are the two important problems associated with wastewater treatment plant. MBR process has been known as a process with relatively high decay rate and less sludge production due to much longer sludge age in the reactor (Wenet al., 2004). Sludge production in MBR is reduced by 28-68%, depending on the sludge age used (Xia et al.,2008). However, minimizing the sludge production by increasing sludge age is limited due to the potential adverse effect of high MLSS concentrations on membrane (Yoon et al., 2004). This problem can be solved by introducing sludge disintegration technique in MBR (Young et al., 2007). Sludge disintegration techniques have been reported to enhance the biodegradability of excess sludge (Vlyssides and Karlis, 2004). In overall, the basis for sludge reduction processes is effective combination of the methods for sludge disintegration and biodegradation of treated sludge. Advances in sludge disintegration techniques offer a few promising options including ultrasound (Guo et al., 2008), pulse power (Choi et al.,2006), ozone (Weemaes et al., 2000), thermal (Kim et al., 2003), alkaline (Li et al., 2008) acid (Kim et al., 2003) and thermo chemical(Vlyssides and Karlis, 2004). Among the various disintegration techniques, thermo chemical was reported to be simple and cost effective (Weemaes and Verstraete, 1998). In thermal-chemical hydrolysis, alkali sodium hydroxide was found to be the most effective agent in inducing cell lysis (Rocker et al., 1999). Conventionally, the nutrient removal was carried out in an A2O process. It has advantage of achieving, nutrient removal along with organic compound oxidation in a single sludge configuration using linked reactors in series (Tchobanoglous et al., 2003). The phosphoroes removal happens by subjecting phosphorous accumulating organisms (PAO) bacteria under aerobic and anaerobic conditions (Akin and Ugurlu, 2004). These operating procedures enhance predominance PAO, which are able to uptake phosphorous in excess. During the sludge pretreatment processes the bound phosphorous was solubilised and it increases the phosphorousconcentration in the effluent stream (Nishimura, 2001).So, it is necessary to remove the solubilised phosphorus before it enters into main stream. Besides, there is a growing demand for the sustainable phosphorous resources in the industrialized world. In many developed countries, researches are currently underway to recover the phosphoroes bound in the sludge's of enhanced biological phosphorus removal system (EBPR). The released phosphorous can be recovered in usable products using calcium salts precipitation method. Keeping this fact in mind, in the present study, a new advanced wastewater treatment process is developed by integrating three processes, which are: (a) thermo chemical pretreatment in MBR for excess sludge reduction (b) A2O process for biological nutrient removal (c) P recovery through calcium salt precipitation. The experimental data obtained were then used to evaluate the performance of this integrated system.2. Methods2.1. WastewaterThe synthetic domestic wastewater was used as the experimental influent. It was basically composed of a mixed carbon source, macro nutrients (N and P), an alkalinity control (NaHCO3) and a microelement solution. The composition contained (/L) 210 mg glucose, 200 mg NH4C1, 220 mg NaHCO3, 22一34 mg KH2PO4, microelement solution (0.19 mg MnCl2 4H20, 0.0018 mg ZnCl22H2O,0.022 mg CuCl22H2O, 5.6 mg MgSO47H2O, 0.88 mg FeCl36H2O,1.3 mg CaCl2·2H2O). The synthetic wastewater was prepared three times a week with concentrations of 210±1.5 mg/L chemical oxygen demand (COD), 40±1 mg/L total nitrogen (TN) and 5.5 mg/L total phosphorus (TP).2.2. A2O-MBRThe working volume of the A2O-MBR was 83.4 L. A baffle was placed inside the reactor to divide it into anaerobic (8.4 L) anoxic (25 L) and aerobic basin (50 L). The synthetic wastewater was feed into the reactor at a flow rate of 8.4 L/h (Q) using a feed pump. A liquid level sensor, planted in aerobic basin of A2O-MBR controlled the flow of influent. The HRT of anaerobic, anoxic and aerobic basins were 1, 3 and 6 h, respectively. In order to facilitate nutrient removal, the reactor was provided with two internal recycle (1R). IRl (Q= 1)connects anoxic and anaerobic and IR 2 (Q=3) was between aerobic and anoxic. Anaerobic and anoxic basins were provided with low speed mixer to keep the mixed liquid suspended solids (MLSS) in suspension. In the aerobic zone, diffusers were used to generate air bubbles for oxidation of organics and ammonia. Dissolved oxygen (DO) concentration in the aerobic basin was maintained at 3.5 mg/1 and was monitored continuously through online DO meter. The solid liquid separation happens inaerobic basin with the help of five flat sheet membranes having a pore size of 0.23 pm. The area of each membrane was 0.1 m2. They were connected together by a common tube. A peristaltic pumpwas connected in the common tube to generate suction pressure. In the common tube provision was made to accommodate pressure gauge to measure transmembrane pressure (TMP) during suction. The suction pump was operated in sequence of timing, which consists of 10 min switch on, and 2 min switch off.2.3. Thermo chemical digestion of sludgeMixed liquor from aerobic basin of MBR was withdrawn at the ratio of 1.5% of Q/day and subjected to thermo chemical digestion. Thermo chemical digestion was carried out at a fixed pH of 11(NaOH) and temperature of 75℃for 3 h. After thermo chemical digestion the supernatant and sludge were separated. The thermo-chemicallydigested sludge was amenable to further anaerobic bio-degradation (Vlyssides and Karlis, 2004), so it was sent to theanaerobic basin of the MBR2.4. Phosphorus recoveryLime was used as a precipitant to recover the phosphorous in the supernatant. After the recovery of precipitant the content was sent back to anoxic tank as a carbon source and alkalinity supelement for denitrification.2.5. Chemical analysisCOD, MLSS, TP, TN of the raw and treated wastewater were analyzed following methods detailed in (APHA, 2003). The influent and effluent ammonia concentration was measured using an ion-selective electrode (Thereto Orion, Model: 95一12). Nitrate in the sample was analyzed using cadmium reduction method (APHA, 2003).3. Results and discussionFig. 1 presents data of MLSS and yield observed during the operational period of the reactor. One of the advantages of MBR reactor was it can be operated in high MLSS concentration. The reactor was seeded with EBPR sludge from the Kiheung, sewage treatment plant, Korea. The reactor was startup with the MLSS concentration of 5700 mg/L. It starts to increase steadily with increase in period of reactor operation and reached a value of 8100 mg/L on day 38. From then onwards, MLSS concentration was maintained in the range of 7500 mg/L by withdrawing excess sludge produced and called run I. The observed yields (Yobs) for experiments without sludge digestion (run I) and with sludge digestion were calculated and given in Fig. 1. The Yobs for run I was found to be 0.12 gMLSS/g COD. It was comparatively lower than a value of 0.4 gMLSS/g CODreported for the conventional activated sludge processes (Tchoba-noglous et al., 2003). The difference in observed yield of these two systems is attributed to their working MLSS concentration. At high MLSS concentration the yield observed was found to be low (Visva-nathan et al., 2000). As a result of that MBR generated less sludge.The presently used MLSS ranges (7.5一10.5 g/L) are selected on the basis of the recommendation by Rosenberger et al. (2002). In their study, they reported that the general trend of MLSS increase on fouling in municipal applications seems to result in no impact at medium MLSS concentrations (7一12 g/L).It is evident from the data that the COD removal efficiency of A2O system remains unaffected before and after the introduction of sludge digestion practices. A test analysis showed that the differences between the period without sludge digestion (run I) and with sludge digestion (run II and III) are not statistically significant.However, it has been reported that, in wastewater treatment processes including disintegration-induced sludge degradation, the effluent water quality is slightly detonated due to the release of nondegradable substances such as soluble microbial products (Ya-sui and Shibata, 1994; Salcai et al., 1997; Yoon et al., 2004). During the study period, COD concentration in the aerobic basin of MBR was in the range of 18-38 mg/L and corresponding organic concentration in the effluent was varied from 4 to 12 mg/L. From this data it can be concluded that the membrane separation played an important role in providing the excellent and stable effluent quality.Phosphorus is the primary nutrient responsible for algal bloom and it is necessary to reduce the concentration of phosphorus in treated wastewater to prevent the algal bloom. Fortunately its growth can be inhibited at the levels of TP well below 1 mg/L (Mer-vat and Logan, 1996).Fig. 2 depicts TP removal efficiency of the A2O-MBR system during the period of study. It is clearly evident from the figure that the TP removal efficiency of A/O system was remains unaffected after the introduction of sludge reduction. In the present study, the solubilised phosphorous was recovered in the form of calcium phosphate before it enters into main stream. So, the possibility of phosphorus increase in the effluent due to sludge reduction practices has been eliminated. The influent TP concentration was in the range of 5.5 mg/L. During thefirst four weeks of operation the TP removal efficiency of the system was not efficient as the TP concentration in the effluent exceeds over 2.5 mg/L. The lower TP removal efficiency during the initial period was due to the slow growing nature of PAO organisms and other operational factors such as anaerobic condition and internal recycling. After the initial period, the TP removal efficiency in the effluent starts to increase with increase in period of operation. TP removal in A2O process is mainly through PAO organisms. These organisms are slow growing in nature and susceptible to various physicochemical factors (Carlos et al., 2008). During the study period TP removal efficiency of the system remains unaffected and was in the range of 74-82%.。

冰冻浓缩效应绿色合成英文The "cryo-concentration effect" refers to the processin which a liquid mixture is cooled to a temperature below the freezing point of the solvent, causing the formation of ice crystals. This results in the separation of the solvent from the solute, leading to a more concentrated solution. The cryo-concentration effect is often utilized in various industries, such as the food and beverage industry, for the production of concentrated juices and other liquid products.On the other hand, "green synthesis" refers to the development of chemical processes for the production of various compounds and materials that are environmentally friendly. This approach aims to minimize the use of hazardous substances, reduce waste generation, and promote sustainable practices. Green synthesis methods ofteninvolve the use of renewable resources, non-toxic solvents, and energy-efficient processes.In summary, the "cryo-concentration effect" involvesthe separation and concentration of a liquid mixture through freezing, while "green synthesis" pertains to the environmentally friendly production of compounds and materials. Both concepts are important in their respective fields and contribute to sustainable and responsible manufacturing practices.。

孙梦，冉佩灵，黄业传，等. 超高压杀菌对低盐切片腊肉风味及理化性质的影响[J]. 食品工业科技，2024，45（2）：101−109. doi:10.13386/j.issn1002-0306.2023040209SUN Meng, RAN Peiling, HUANG Yechuan, et al. Effect of Ultra-high-pressure Sterilization on Flavor and Physicochemical Properties of Low-salt Sliced Bacon[J]. Science and Technology of Food Industry, 2024, 45(2): 101−109. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2023040209· 研究与探讨 ·超高压杀菌对低盐切片腊肉风味及理化性质的影响孙　梦1，冉佩灵1,2, +，黄业传2, *，李占阳1（1.西南科技大学生命科学与工程学院，四川绵阳 621000；2.荆楚理工学院生物工程学院，湖北荆门 448000）摘　要：为探究不同压力的超高压杀菌对低盐切片腊肉品质的影响，样品在22 ℃下分别经200、400、600 MPa 压力处理10 min ，以未杀菌组为对照，于4 ℃储藏的第0、60、120、180 d 测定理化指标、风味物质及菌落总数。

结果表明，超高压处理后，低盐切片腊肉的水分含量、亚硝酸盐含量、硬度、a *值、b *值及菌落总数均降低，pH 、POV 值、L *值、弹性、回复力及内聚性均升高。

储藏过程中，超高压增强了腊肉的持水性，减缓了脂肪氧化，有效抑制了微生物生长。

第180 d 时，超高压组的水分含量、L *值、a *值、弹性及内聚性均高于对照组，pH 、亚硝酸盐含量、硬度及菌落总数均低于对照组。

2024年2月Feb.2024第48卷第1期Vol.48，No.1热带农业工程TROPICAL AGRICULTURAL ENCINEERING不同初始pH 值对白菜尾菜与羊粪混合厌氧发酵的影响申岳1,2蔡立群1,2陈晓龙1,2王勇智1,2周生虎1,2（1甘肃农业大学资源与环境学院甘肃兰州730070；2甘肃省干旱生境作物学重点试验室甘肃兰州730070）摘要探究不同初始pH 对白菜尾菜与羊粪混合厌氧发酵的影响，为尾菜沼气工程预处理技术提供理论基础。

利用自制小型发酵装置，以白菜尾菜为主要原料，添加适量羊粪防止发酵系统酸化，导致产气停滞，将白菜尾菜与羊粪按总固体含量（TS ）2∶1进行混合，设置4个不同初始pH 值处理（T1：pH 值未调节，pH =7.1±0.1；T2：pH =6.5±0.1；T3：pH =7.5±0.1；T4：pH =8.5±0.1），高温条件下（55±1）℃进行湿式厌氧发酵。

研究不同初始pH 值对白菜尾菜和羊粪混合发酵过程中产甲烷效能、发酵基质有机质水解、发酵系统稳定性的影响。

与T1相比，T3处理能有效增加白菜尾菜与羊粪混合厌氧发酵的产甲烷效能；碱性条件下能进一步促进固态有机物的水解，提高发酵液中有机质含量；各发酵系统均能较稳定运行，更有利于白菜尾菜与羊粪厌氧发酵的进行。

本结论可为白菜尾菜沼气化利用提供一定的理论及应用参考。

关键词pH 值；尾菜；混合发酵；羊粪；甲烷中图分类号TQ921；X72Effects of Different Initial PH Values on Mixed Anaerobic Fermentationof Cabbage Tail and Sheep ManureSHEN Yue 1,2CAI Liqun 1,2CHEN Xiaolong 1,2WANG Yongzhi 1,2ZHOU Shenghu 1,2(1College of Resources and Environment Science,Gansu Agricultural University,Lanzhou,Gansu 730070;2State Key Laboratory of Aridland Crop Science,Lanzhou,Gansu 730070)AbstractThe effects of different initial pH on mixed anaerobic fermentation of cabbage tail and sheepmanure were investigated to provide a theoretical basis for the pretreatment technology of vegetable tail methane ing a self-made small-scale fermentation device,with cabbage tail as the main raw material,an appropriate amount of sheep manure was added to prevent acidification of the fermentation system,resulting in stagnation of gas production.The cabbage tail and sheep manure were mixed according to the total solid content (TS)of 2:1,and four different initial pH values were set (T1:pH was not adjusted,pH =7.1±0.1;T2:pH =6.5±0.1;T3:pH =7.5±0.1;T4:pH =8.5±0.1),wet anaerobic fermentation under high temperature conditions (55±1)°C.The effects of different initial pH values on methane-producing efficiency,organic matter hydrolysis in fermentation substrate and stability of fermentation system during mixed fermentation of cabbage tail and sheep manure were pared with T1,T3treatment could effectively increase the methane production efficiency of mixed anaerobic of cabbage tail and sheep manure.Under alkaline conditions,it can further promote the hydrolysis of solid organic matter and increase the content of organic matter in the fermentation solution.Each fermentation system can operate stably,which is more conducive to the anaerobic fermentation of cabbage tail and sheep manure.This基金项目：甘肃省教育厅高校产业支撑项目（No.2021CYZC-50）。

盐碱地综合利用表态发言英文回答：Saline-alkali land is a common problem in many regions, and it poses a significant challenge for agricultural development. However, with the right approach, saline-alkali land can be effectively utilized for various purposes, such as agriculture, aquaculture, and renewable energy production.First and foremost, saline-alkali land can be used for salt-tolerant crop cultivation. Certain crops, such as quinoa, barley, and saltgrass, have the ability to thrivein high-salinity soils. By promoting the cultivation of these salt-tolerant crops, we can make productive use of saline-alkali land and generate economic benefits for local communities.In addition to agriculture, saline-alkali land can also be utilized for aquaculture. Fish species such as tilapiaand mullet are known for their tolerance to brackish water, making them suitable for aquaculture in saline-alkali areas. By establishing fish farms in these regions, we can notonly make use of the land but also contribute to the supply of seafood products.Furthermore, saline-alkali land holds potential for renewable energy production. For instance, the cultivationof salt-tolerant plants can be combined with bioenergy production, such as the generation of biofuels from salt-tolerant crop residues. Additionally, the installation of solar panels on saline-alkali land can harness solar energy for electricity generation.In conclusion, the comprehensive utilization of saline-alkali land offers promising opportunities for sustainable development. By exploring its potential for agriculture, aquaculture, and renewable energy production, we can turn a challenging problem into a source of economic growth and environmental benefit.中文回答：盐碱地是许多地区普遍存在的问题，对农业发展构成了重大挑战。

农作物耐盐碱机制解析及应用## Crop Salt and Alkali Tolerance Mechanisms and Applications.### English Answer:Salt and alkali stress are major environmental challenges that restrict crop growth and productivity in many regions worldwide. To cope with these stresses, crops have evolved various mechanisms to maintain cellular homeostasis and mitigate the toxic effects of salt and alkali ions. Understanding these mechanisms is crucial for developing effective strategies to improve crop salt and alkali tolerance.One of the primary mechanisms of salt and alkali tolerance in crops is ion exclusion. Ion exclusion prevents the influx of harmful ions, such as sodium (Na+) and chloride (Cl-), into the plant roots and shoots. This is achieved through various ion transporters and channelspresent in the root cell membranes. For example, salt overly sensitive 1 (SOS1) is a critical sodium/hydrogen antiporter that pumps Na+ out of the root cells, maintaining a low cytoplasmic Na+ concentration.Another important mechanism is tissue tolerance. Tissue tolerance involves the compartmentalization and detoxification of salt and alkali ions that have entered the plant tissues. This includes the sequestration of ions into vacuoles, where they are stored and prevented from causing damage to cellular components. Additionally, crops may accumulate compatible solutes, such as proline and glycine betaine, which help maintain cell turgor and protect enzymes and proteins from salt and alkali stress.Molecular and genetic approaches have been employed to identify genes and pathways involved in salt and alkali tolerance in crops. Several quantitative trait loci (QTLs) and candidate genes have been identified that control ion exclusion and tissue tolerance mechanisms. Genetic engineering techniques are being used to introgress these salt tolerance genes into elite cultivars to enhance theirperformance in saline and alkaline soils.### 中文回答：农作物耐盐碱机制解析及应用。

中国生态农业学报(中英文) 2024年4月 第 32 卷 第 4 期Chinese Journal of Eco-Agriculture, Apr. 2024, 32(4): 687−700DOI: 10.12357/cjea.20230644任羽飞, 封晓辉, 李静, 郭凯, 李伟柳, 吴玉洁, 刘小京. 遮荫对盐胁迫下油葵生长和光合生理的影响[J]. 中国生态农业学报 (中英文), 2024, 32(4): 687−700REN Y F, FENG X H, LI J, GUO K, LI W L, WU Y J, LIU X J. Impact of shading on growth and photosynthetic physiology traits of Helianthus annuus L. under salt stress[J]. Chinese Journal of Eco-Agriculture, 2024, 32(4): 687−700遮荫对盐胁迫下油葵生长和光合生理的影响*任羽飞1,2, 封晓辉1, 李　静1,2, 郭　凯1, 李伟柳1,2, 吴玉洁1,2, 刘小京1,2**(1. 河北省土壤生态学重点实验室/中国科学院盐碱地资源高效利用工程实验室/中国科学院农业水资源重点实验室/中国科学院遗传与发育生物学研究所农业资源研究中心　石家庄　050022; 2. 中国科学院大学　北京　100049)摘　要: 盐碱地光伏系统下作物生长受到盐分和遮荫的双重影响, 研究双重逆境下作物的生理响应对该系统内作物种植有重要指导意义。

本研究以油葵(Helianthus annuus L.)为试验材料, 采用盆栽试验, 设3个盐分水平(在初始含盐量的基础上外加NaCl含量0 g·kg−1、3 g·kg−1和5 g·kg−1)和4个遮荫水平(0%、30%、60%和90%), 探究遮荫对盐胁迫下油葵生长、光合特性、叶片解剖结构、生物量积累和分配及籽粒产量等的影响, 为盐碱地光伏系统下开展作物种植提供理论依据。

颜茜，汪超凡，朱康伟，等. 醋糟阿拉伯木聚糖的提取工艺优化及其对馒头品质的影响[J]. 食品工业科技，2023，44（10）：211−218.doi: 10.13386/j.issn1002-0306.2022080051YAN Qian, WANG Chaofan, ZHU Kangwei, et al. Optimization of Process for Preparation of Arabinoxylan from Vinegar Residue and Its Effect on the Quality of Steamed Bread[J]. Science and Technology of Food Industry, 2023, 44(10): 211−218. (in Chinese with English abstract). doi: 10.13386/j.issn1002-0306.2022080051· 工艺技术 ·醋糟阿拉伯木聚糖的提取工艺优化及其对馒头品质的影响颜　茜，汪超凡，朱康伟，余永建*，朱圆圆*（江苏科技大学粮食学院，江苏镇江 212000）摘　要：采用碱提法从醋糟中提取阿拉伯木聚糖。

对NaOH （含0.88% H 2O 2）浓度、提取温度、料液比、提取时间进行单因素实验，得到阿拉伯木聚糖得率最高的四个参数水平，并在此基础上，利用响应面法优化碱提阿拉伯木聚糖最佳工艺条件，并对优化工艺所得的多糖进行了单糖组成分析、分子量等分析以及对馒头品质的影响。

结果表明：最佳实验条件为：NaOH （含0.88% H 2O 2）浓度0.92 mol/L ，提取温度75 ℃，料液比1:35 g/mL ，提取时间1.5 h ，所得阿拉伯木聚糖得率为8.75%。

得到醋糟阿拉伯木聚糖（AX ）主要由阿拉伯糖、半乳糖、葡萄糖、木糖、半乳糖醛酸、葡萄糖醛酸6种单糖组成，含量分别为38.9%、1.32%、2.37%、55.84%、0.66%、0.91%。

GEOLOGY , December 2008 959Geology , December 2008; v. 36; no. 12; p. 959–962; doi: 10.1130/G25285A.1; 3 fi gures; Data Repository item 2008240.© 2008 The Geological Society of America. For permission to copy, contact Copyright Permissions, GSA, or editing@.INTRODUCTIONOn 21 August 2004, a small fi re occurred in a remote location in the Dick Smith Wilderness. The smoke was reported, and rapid response by Los Padres National Forest fi re crews quickly extinguished the fi re. Inves-tigation revealed that the fi re originated near the center of a recent 7 ha landslide (Fig. 1) where hot gas was discharging. The fumaroles occur on topographic highs in the middle and upper parts of the landslide. Measured temperatures in some fumaroles were signifi cantly above the spontaneous combustion temperature of dry grass (150 to 200 °C) and were approach-ing the spontaneous combustion temperature (300 °C) of bituminous coal (/fuels-ignition-temperatures-d_171.html). The hottest fumarole (B2 on Fig. 1) is located just above a particu-larly steep part of the slide and is oriented directly into the prevailing wind from the west. The slide is not visible on air photographs taken in 1989, but is present on photographs taken in 2002. Near-record rainfall in 1998 may have initiated slide movement.Few natural processes can generate such high temperatures at Earth’s surface. These include spontaneous heating (oxidation) of fi ne-grained sulfi de, combustion of iron sulfi de–bearing coal, combustion metamorphism associated with oil fi elds, ignited natural gas seeps, vol-canic activity, and spontaneous combustion of drying vegetation. Each process has geologic, chemical, and isotopic characteristics that should make it possible to admit or reject it as the source of heat and gas at this site. The process (or combination of processes) must be geologically reasonable in landslides involving rock of this age and type, must be capable of producing high temperatures, and must be able to produce the chemical and isotopic compositions of the gas discharged by the fuma-roles. If spontaneous heating (oxidation) of pyrite is a source of heat, then there must be enough fi ne-grained pyrite in the rock to heat the rock to the observed temperatures when it is oxidized. If combustion of iron sulfi de–bearing coal is the source of heat, then iron sulfi de–bearingcoal must occur at other places in the formation, and some of the varioushydrated sulfates associated with oxidation of pyrite in coalfi elds should be present. If combustion metamorphism is a major process, then there should be evidence of extremely high temperatures (>500 °C) in the dis-charged gas. If natural gas seeps are involved, then the methane, ethane, and propane proportions and isotopic compositions must be typical for natural gas in this area. If volcanic activity is the source of the heat, then the superheated fumaroles should have high gas fl ow rates, high 3He/4He values, excess nitrogen, and high CO 2 concentrations. Carbon dioxide generated by spontaneous combustion of modern plant material would have modern 14C values.METHODSTo investigate the origin of the heat, samples of rock, water, and gas were collected from the landslide for chemical and isotope analyses. Rep-licate gas samples were collected from boreholes (perforated 190 mm OD pipes driven as much as 4 m into the slide mass); bottomhole tempera-tures were measured by thermocouple. Water samples were collected from intermittent springs at the toe of the slide.GEOLOGIC SETTINGThe bedrock underlying the landslide, and incorporated in it, is marine shale and interbedded, thin, commonly silty sandstone of the Middle Eocene Juncal Formation. In the area of the landslide, the Juncal Formation has a minimum stratigraphic thickness of ~4000 m; however, the Juncal rocks beneath the slide may be truncated by a fault at a depth of as little as 500 m. Beds in the Juncal Formation locally contain carbona-ceous matter and fi ne-grained pyrite (Vedder et al., 1973). A sandstone-rich interval as thick as 20 m (Tjss, Fig. 1) projects downdip roughly 60 m beneath the landslide. On the hillside containing the landslide, the formation dips 20°–30° to the southwest (Fig. 1), approximatelyA landslide in Tertiary marine shale with superheatedfumaroles, Coast Ranges, CaliforniaRobert H. Mariner 1, Scott A. Minor 2, Allen P . King 3, James R. Boles 4, Karl S. Kellogg 2,William C. Evans 1, Gary A. Landis 5, Andrew G. Hunt 5, Christy B. Till 61U.S. Geological Survey, MS 434, 345 Middlefi eld Road, Menlo Park, California 94025, USA2U.S. Geological Survey, MS 980, Federal Center, Denver, Colorado 80225, USA 3Los Padres National Forest, 6755 Hollister Avenue, Goleta, California 93117, USA 4Department of Earth Science, University of California, Santa Barbara, California 93106, USA5U.S. Geological Survey, MS 963, Federal Center, Denver, Colorado 80225, USA6Department of Earth, Atmosphere, and Planetary Science, Massachusetts Institute of Technology,77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USAABSTRACTIn August 2004, a National Forest fi re crew extinguished a 1.2 ha fi re in a wilderness area ~40 km northeast of Santa Barbara, California. Examination revealed that the fi re originated on a landslide dotted with superheated fumaroles. A 4 m borehole punched near the hottest (262 °C) fumarole had a maximum temperature of 307 °C. Temperatures in this borehole have been decreasing by ~0.1 °C/d, although the cooling rate is higher when the slide is dry. Gas from the fumaroles and boreholes is mostly air with 3–8 vol% carbon dioxide and trace amounts of carbon monoxide, methane, ethane, and propane. The car-bon dioxide is 14C-dead. The ratios of methane to ethane plus propane [C 1/(C 2 + C 3)] range from 3.6 to 14. Carbon isotope values for the CO 2 range from –14‰ to –23‰ δ13C. 3He/4He values range from 0.96 to 0.97 times that of air. The anomalous heat is interpreted to be due to rapid oxidation of iron sulfi de augmented by combustion of carbonaceous matter within the formation.960 GEOLOGY , December 2008p arallel to the slope. Landslide movement likely occurred along bed-ding planes within the Juncal Formation. Some of the landslide and creek bed below the slide mass are coated with a white effl orescence (gypsum and subordinate hydrated magnesium sulfates); similar depos-its not associated with landslides or hot vents occur in adjacent can-yons. No other sulfate minerals were present. Thirteen other landslidesof similar size occur in outcrops of the Juncal Formation within 8 km of the landslide in Deal Canyon (see Dibblee, 2006). Thermal IR imagery of the region taken by the Forest Service after the fi re did not show any hot areas beyond the slide.ANALYTICAL RESULTS Sulfur and Carbon Analyses from Bedrock Samples Ten samples of shale or fi ne-grained shaly sandstone collected from the landslide block and the intact bedrock outcrops adjacent to the landslide were analyzed for total carbon and sulfur. A few fi ne grains of pyrite are visible in several of the hand samples; several other samples contain black fl ecks of carbonaceous material as long as 5 mm. No large concentrations of sulfi des or carbonaceous material were found in either the landslide or the adjacent bedrock; all samples resemble typical shale or fi ne-grained sandstone found regionally in the Juncal Formation (e.g., Vedder et al., 1973; Minor, 2004). Microscope and scanning electron microscope (SE M) analyses show that pyrite in typical Juncal shale occurs in framboidal arrays near bits of carbonaceous material. Total sulfur is ≤1.8 wt% (dry basis) in all samples; total organic carbon is ≤1.9 wt%. If all of the sulfur were in pyrite, then pyrite would make up asmuch as 3.5 wt% of the average shale. However, a zone several metersthick near the toe of the landslide contains abundant small iron oxidenodules (Fig. 2) that must have initially been pyrite. These hematite-bearing nodules contain 11.8 wt% FeTO 3 and show that pyrite could locally have been ~18 wt% of the rock.GSA Data Reposi-tory.1 Repetitive measurements show that temperatures in borehole B2 decreased ~0.09 °C/d between 16 December 2004 and 16 January 2008. Temperatures as high as 288 °C were measured near B2 by drive probes at depths of only 0.36 m in December 2004. A data logger installed on borehole B2 on 26 June 2007 showed that the temperature in the boreholedecreased by 0.105 °C/d until 20 September 2007 when the rate slowed to only 0.051 °C/d. The first major rain during the period of record occurred on 20 September, and additional rain fell in the middle of October.Gas SamplesGases (Table DR1) from the fumaroles and boreholes are mainly nitrogen (80–84 vol%) with significant amounts of oxygen (7–16 vol%), carbon dioxide (3–8 vol%), and argon (0.9–1.0 vol%). Trace amounts of carbon monoxide, hydrogen, methane, ethane, propane, and helium arealso present. Hydrogen sulfi de, sulfur dioxide, and butane concentra-tions are less than 0.0002 vol%. The average N 2/Ar for all samples isessentially identical to air. Borehole B2 and the adjacent fumarole were initially ~5.9 vol% carbon dioxide, but concentrations in the borehole havenow decreased to ~4.0 vol%. Borehole B6 has varied from ~8 to ~5 vol% carbon dioxide without a clear trend over time. As carbon d ioxide con-centrations have decreased, oxygen concentrations have increased. Ratios of carbon monoxide to carbon dioxide in borehole B2 have been rela-tively constant as oxygen content has increased; but in B6, ratios of carbon monoxide to carbon dioxide have decreased by almost a factor of ten as oxygen content has increased. The apparent decrease in carbon monoxide at B6 is not due to mixing with air; it may be due to more complete com-bustion as the amount of combustible matter has decreased.The CO 2 discharged from the boreholes has δ13C values ranging from –14‰ to –23‰ (Table DR2). The carbon isotopic composition (δ13C) for carbon dioxide from borehole B6 was initially ~–14‰ but is are Tertiary Juncal Formation shale and sandstone, respectively.1GSA Data Repository item 2008240, measured temperatures, chemi-cal compositions and isotope values for gases and waters, gas geothermometer values , and ratio of moles oxygen consumed to moles carbon dioxide producedfor gas, is available online at /pubs/ft2008.htm, or on request from editing@ or Documents Secretary, GSA, P.O. Box 9140, Boulder, CO 80301, USA.GEOLOGY , December 2008961now ~–19‰. This change took place in early 2005. Borehole B2 shows similar changes, but isotopic data for it are incomplete; carbon dioxide from it is now ~–23‰ δ13C. δ13C values for CO 2 from B2 and B6 have been stable since June 2005. The small amount of 14C (0.76 percent of modern carbon) in the gases could be from carbon dioxide naturally in air and soil gas. Helium, neon, argon, krypton, and xenon isotope ratios are very near atmospheric values (Table DR3). There is too little methane to get an isotopic value on it. A team from Lawrence Livermore National Laboratory examined the landslide on 21 and 22 September 2005. They detected no anomalous radiation in the rock of the landslide or in the gas discharging from it (G. Schwichert, 2005, person. commun.).Water Samples Two ephemeral springs at the toe of the slide discharge small amounts of magnesium sulfate water (Table DR4). The pH of these waters ranges from 5.4 to 5.9, and they vary seasonally in conductance and discharge. Sulfate (4540–9164 mg/L) makes up ~95 wt% of the anions and has a δ34S of –15.8‰. Chloride is <25 mg/L. Alkalinity ranges from 236 to 361 mg/L HCO 3. Sulfi de is <0.5 mg/L by titration in the fi eld. Magne-sium concentrations range from 800 to 2000 mg/L, sodium from 150 to 400 mg/L, and calcium from 400 to 500 mg/L. δD and δ18O values in the spring waters vary due to evaporation.DISCUSSIONSuperheated fumaroles such as B2 (262 °C) and B6 (113 °C) aretypically found only on volcanoes that are discharging unusually large volumes of volcanic gas. There are no volcanoes in the area, and the vol-ume of gas being discharged from the fumaroles and boreholes is very low. The 3He/4He values for samples from fumaroles on the landslide areessentially that of air with perhaps a little radiogenic (crustal) helium; there is no excess nitrogen; and carbon dioxide makes up less than8 vol% of the discharged gas. The gas discharging from the landslide is not associated with magmatic fl uids. Combustion of modern organic material (e.g., tree roots and debris) incorporated in the landslide can-not be important because carbon dioxide escaping from the landslide is essentially bustion metamorphism has been described from hydrocarbon-rich sites at several places in the Coast Ranges (Cisowski and Fuller, 1987; Lore et al., 2002; Bentor and Kastner, 1976), but never from the Juncal Formation. Magnetic anomalies were associated with combustion sites near small oil fi elds in the Monterey and Sisquoc Formations (Cisowski and Fuller, 1987). A cursory magnetic survey across the hot part of the Deal Canyon landslide did not reveal any magnetic anomalies, but tem-peratures in systems with magnetic anomalies were much hotter (up to 1100 °C based on secondary minerals). If the constituents of the gas recov-ered from the boreholes were in chemical equilibrium in the landslide, and if the gas composition had not changed as it rose toward the surface, then gas geothermometers could be used to estimate temperatures in the slide mass. The CO 2-CH 4 geothermometer preserves evidence of high tempera-tures very well (Giggenbach, 1992); it gives temperatures for borehole B2that range from 312 to 329 °C (Table DR5). The reaction between coal and water vapor to produce hydrogen and carbon dioxide, 2H 2O + C (coal) → 2H 2 + CO 2, (1)has been used as a C-H 2-CO 2 gas geothermometer in the Cerro Prieto, Mexico, geothermal fi eld (Nehring and D’Amore, 1984). The Cerro Prieto fi eld is in coal-bearing Early Tertiary sediments at the north end of the landward extension of the Gulf of California rift zone. Temperatures calculated from this geothermometer for the B2 borehole range from 305 to 361 °C (Table DR5). There is no evidence of very high temperatures in the landslide. Combustion metamorphism is unlikely.Ratios of methane to ethane plus propane [C 1/(C 2 + C 3)] of the escap-ing gas range from 4 to 14 (Table DR5). Burning consumes more of thelonger-chain hydrocarbons, so more long-chain hydrocarbons should have been present relative to methane prior to combustion. These C 1/(C 2 + C 3) values are in the range produced by high-temperature (catagenetic)p rocesses (Bernard et al., 1976) and are similar to values for natural seeps in the Santa Barbara Channel (Clark et al., 2000). If all of the car-bon dioxide in our samples were from burning hydrocarbons, then the methane would have been near –20‰ δ13C, appreciably heavier than the methane (–40‰ to –48‰ δ13C) from the marine seeps of Coal Oil Point in the Santa Barbara Channel (Boles et al., 2001) and the petroleum seeps in the Upper Ojai V alley (Duffy et al., 2007). Coal Oil Point is ~30 milessouthwest of Deal Canyon, and the Upper Ojai V alley a similar distanceto the southeast; neither of these seeps is in the Juncal Formation. Natu-ral gas seeps usually also have excess nitrogen, but samples from the hot landslide have no excess nitrogen. A natural gas seep is probably not the source of the carbon gases escaping from the hot landslide.It may be possible to determine the source of the carbon dioxide by looking at the ratio of oxygen consumed to carbon dioxide produced. The amount of oxygen consumed is the difference between the moles of oxy-gen that should be present based on the moles of nitrogen in the analysis(O 2/N 2 = 0.269 for air) and the moles of oxygen present in the gas col-lected from the fumarole or well. The ratio of moles oxygen consumed to moles carbon dioxide produced is 1 for burning coal or wood,C (or CH 2O) + O 2 → CO 2 (+ H 2O), (2)2 for burning methane, CH 4 + 2O 2 → CO 2 + 2H 2O, (3)and 1.75 for burning ethane. Gases from the landslide have ratios of oxygen consumed to carbon dioxide produced that range from 1.63 to 2.14 at B6 and from 1.74 to 1.95 at B2 (Fig. 3; Table DR5). Several ratios of oxygen consumed to carbon dioxide produced at B6 are greater than 2 (Fig. 3) and require a reaction that consumes oxygen without producing carbon dioxide.The generally lower ratio at B2 (Fig. 3) may be from burning more finely disseminated carbonaceous matter, and this may be the reason that the area near B2 is hotter than the area near B6. Alternatively, B2 is lower on the slide, and gas rising through the slide may have experienced less burning than gas recovered higher on the slide at B6. In mixtures of hydrocarbons,the heavier hydrocarbons tend to burn first. The heavier ethane and propane would burn preferentially at lower elevations to produce ratios of oxygen consumed to carbon dioxide produced closer to that expected for burning ethane and higher C 1/(C 2 + C 3) values. The remaining methane would burn farther up the slide to produce higher ratios of oxygen consumed to carbon dioxide produced and lower C 1/(C 2 + C 3) values. However, this explanation does not fi t the data because C 1/(C 2 + C 3) values are higher at B6 (higher elevation) than at B2 (lower elevation).Fig ure 3. Ratio of moles oxyg en consumed to moles carbon dioxideproduced as a functionof time for gas from wellsB2 (diamonds) and B6(triang les). Dashed lines show the ratios of oxy-g en consumed to moles carbon dioxide produced for burning coal (1.0),burninge thane (1.75),burning methane (2.0), and the pyrite oxidation reaction from equa-tion 4 (1.875)..811.21.41.61.822.22.4O x y g e n c o n s u m e d-------------------------------C a r b o n d i o x i d e p r o d u c e d[]Time962 GEOLOGY , December 2008Spontaneous heating of sulfi de ores and, in some cases, combustion of iron sulfi de–bearing coal have been reported in numerous mine andmilling operations (e.g., Liao and Li, 1986; Wiese et al., 1987; Ninteman, 1978; Pikhlak et al., 1969). Oxidation of pyrite in the presence of calcite and water would produce hematite, gypsum, and carbon dioxide:2FeS 2 + 4CaCO 3 + 8H 2O + 71/2O 2 → 4CaSO 4·2H 2O + Fe 2O 3 + 4CO 2. (4)The reaction releases 1388 kJ/mol of pyrite. If pyrite locally had made up 5 wt% of the rock, and if all of the released energy had heated the shale(heat capacity of 0.85 J/g/°C), then the fi nal temperature of the dry rockwould be ~700 °C. If the rock were water-saturated and had 15% poros-ity, then the temperature would be ~450 °C. Spontaneous combustion of bituminous coal occurs at 300 °C; heat from pyrite oxidation could haveignited carbonaceous matter near it. Dissolved sulfate from the spring at the toe of the slide has a δ34S value of –15.8‰, a common value for biogenic pyrite in marine shale (Clark and Fritz, 1997). Early Tertiary marine sulfate is ~+18‰ δ34S (Claypool et al., 1980) and cannot be the source of the dissolved sulfate. The water in the springs at the toe of theslide is very slightly acidic (pH 5–5.5) and contains no sulfi de. The ratioof oxygen consumed to carbon dioxide produced for equation 4 is 1.875 (Fig. 3), the same as the average (1.88) for all samples collected from B6 and B2. However, the δ13C of the carbon dioxide in our samples ismore depleted than expected from a marine calcite source and may bea mixture of CO 2 from marine calcite and combustion of carbonaceous matter. Oxidation of pyrite can occur by many reactions, and many of these consume oxygen and produce no carbon dioxide. Combustion of coal cannot be the major source of heat because the ratios of oxygen consumed to carbon dioxide produced of the gas escaping from the slideare too high for coal oxidation. Pyrite clearly occurred in local concen-trations in the formation; however, we do not see any of the hydrated iron sulfates (aluminocopiapite, melanterite, fi broferrite, rhomboclase,etc.) that Zodrow et al. (1979) described as typical alteration productsof pyrite in coalfi eld environments. The hydrated sulfates produced by pyrite oxidation are quite soluble and may have been dissolved from the slide surface by winter rains.CONCLUSIONSWe speculate that pyrite in the jumbled blocks of the Juncal shale oxidized rapidly when air was introduced during the initial landslide movement. Rapid oxidation of the pyrite, perhaps accelerated initially bymicrobes, heated the rock enough to ignite dispersed solid carbonaceousmatter present in the shale. Combustion of some carbonaceous matter is necessary to provide the 13C-depleted carbon in the CO 2 escaping from the slide. Changes in C 1/(C 2 + C 3) and in the ratio of moles oxygen consumed to moles carbon dioxide produced over time favor a limited supply of car-bon. Examination of the geochemical data leads us to a solid conclusionas to the source of the heat; we are nonetheless surprised that the phenom-enon is rare because siltstone-shale sequences commonly have pyrite and organic matter and are involved in landslides.ACKNOWLEDGMENTS We thank Peter E ichhubl and E dwin L. Zodrow, whose review comments signifi cantly improved the manuscript.REFERENCES CITEDBentor, Y .K., and Kastner, M., 1976, Combustion metamorphism in southern Cal-ifornia: Science, v. 193, p. 486–488, doi: 10.1126/science.193.4252.486.Bernard, B.B., Brooks, J.M., and Sackett, W.M., 1976, Natural gas seepage in theGulf of Mexico: Earth and Planetary Science Letters, v. 31, p. 48–54, doi: 10.1016/0012-821X(76)90095-9.Boles, J.R., Clark, J.F., Leifer, I., and Washburn, L., 2001, Temporal variation in natural methane seep rate due to tides, Coal Oil Point area, California:Journal of Geophysical Research, v. 106, no. 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VII1–VII7.Lore, J.S., Eichhubl, P., and Aydin, A., 2002, Alteration and fracturing of sili-ceous mudstone during in situ combustion, Orcutt fi eld, California: Jour-nal of Petroleum Science E ngineering, v. 26, p. 169–182, doi: 10.1016/S0920-4105(02)00316-9.Minor, S.A., 2004, Geologic map of the Reyes Peak quadrangle, Ventura County, California: U.S. Geological Survey Open-File Report 2004-1420, scale 1:24,000, 1 sheet.Nehring, N.L., and D’Amore, F., 1984, Gas chemistry and thermometry of theCerro Prieto, Mexico, geothermal fi eld: Geothermics, v. 13, p. 75–89, doi: 10.1016/0375-6505(84)90008-7.Ninteman, D.J., 1978, Spontaneous oxidation and combustion of sulfi de ores in underground mines: U.S. Bureau of Mines Information Circular 8775,36 p.Pikhlak, A.A., Pakhomov, A.S., Rybakov, A.N., and Il’chuk, N.G., 1969, Fire hazard of sulfi de ores from the Talnakh deposit: Gornyi Zhurnal, v. 145,no. 9, p. 20–22.Vedder, J.G., Dibblee, T.W., Jr., and Brown, R.D., Jr., 1973, Geologic map of the upper Mono Creek–Pine Mountain area, California: U.S. GeologicalSurvey Miscellaneous Geological Investigations Map I-752, scale 1:48,000, 1 sheet.Wiese, R.G., Jr., Powell, M.A., and Fyfe, W.S., 1987, Spontaneous formationof hydrated iron sulfi des on laboratory samples of pyrite- and marcasite-bearing coals: Chemical Geology, v. 63, p. 29–38, doi: 10.1016/0009-2541(87)90071-4.Zodrow, E.L., Wiltshire, J., and McCandlish, K., 1979, Hydrated sulfates in theSydney Coalfi eld of Cape Breton, Nova Scotia, II: Pyrite and its alterationproducts: Canadian Mineralogist, v. 17, p. 63–70.Manuscript received 26 June 2008Revised manuscript received 18 August 2008Manuscript accepted 26 August 2008Printed in USA。

麦类作物学报 2024,44(2):222-229J o u r n a l o fT r i t i c e a eC r o ps d o i :10.7606/j.i s s n .1009-1041.2024.02.10网络出版时间:2023-12-20网络出版地址:h t t ps ://l i n k .c n k i .n e t /u r l i d /61.1359.S .20231220.0946.006外源γ-氨基丁酸缓解燕麦幼苗盐碱胁迫的生理效应收稿日期:2023-07-05 修回日期:2023-10-09基金项目:国家重点研发计划国际合作重点专项(2018Y F E 0107900);国家燕麦荞麦产业技术体系项目(C A R S -07);内蒙古自治区燕麦工程实验室创新能力建设项目(B R 221023);燕麦抗逆种质资源评价㊁新品种选育与利用;内蒙古乔大专项(2021Z D 0002);内蒙古 揭榜挂帅 项目(2022J B G S 0035);内蒙古自治区科技计划项目(2020G G 0037);呼和浩特市重大科技专项(2022-农-重-2-3)第一作者E -m a i l :a 1345639940@163.c o m (张碧茹)通讯作者E -m a i l :c a u l i h @163.c o m (刘景辉)张碧茹,米俊珍,赵宝平,徐忠山,刘景辉(全国农业科研杰出人才及其创新团队/内蒙古草原英才创新团队/燕麦全产业链创新团队/内蒙古高校燕麦工程研究中心/燕麦内蒙古自治区工程实验室/内蒙古农业大学杂粮产业协同创新中心,内蒙古呼和浩特010019)摘 要:为探究外源γ-氨基丁酸(G A B A )对燕麦耐盐碱性的影响,以燕麦白燕2号为试验材料,在混合盐碱(N a C l ʒN a 2S O 4ʒN a H C O 3ʒN a 2C O 3摩尔比为1ʒ9ʒ9ʒ1)胁迫下叶面喷施不同浓度G A B A ,测定燕麦幼苗叶绿素含量㊁荧光参数㊁渗透调节物质及抗氧化酶活性的变化,同时对幼苗生长缓解效应进行综合评价㊂结果表明,外源喷施4~6mm o l ㊃L -1G A B A 可显著提高盐碱胁迫下燕麦幼苗的叶绿素含量和光系统Ⅱ反应活性,促进光合作用;在盐碱胁迫下,与喷施清水相比,燕麦幼苗叶面喷施不同浓度G A B A 后,脯氨酸(P r o )㊁丙二醛(M D A )和可溶性糖(S S )含量分别下降了14.7%~29.7%㊁28.2%~54.4%和1.8%~11.8%,超氧化物歧化酶(S O D )㊁过氧化物酶(P O D )和过氧化氢酶(C A T )活性分别提高了17.9%~58.3%㊁4.4%~33.4%和8.3%~19.1%㊂经隶属函数法综合评价得出,叶面喷施G A B A 提高燕麦幼苗耐盐碱性的最佳浓度为6mm o l ㊃L -1㊂以上结果说明,叶面喷施适宜浓度的G A B A 能够提高燕麦幼苗光合能力和抗氧化酶活性,降低渗透调节物质含量,提高燕麦幼苗的抗盐碱能力,有效缓解盐碱胁迫对幼苗生长带来的伤害㊂关键词:γ-氨基丁酸;燕麦;盐碱胁迫;生理效应中图分类号:S 156.6;S 311 文献标识码:A 文章编号:1009-1041(2024)02-0222-08P h y s i o l o g i c a l E f f e c t s o fE x o g e n o u sG a m m a -A m i n o b u t yr i c A c i do nS a l t -A l k a l i S t r e s s i nO a t S e e d l i n gs Z H A N GB i r u ,M I J u n z h e n ,Z H A OB a o p i n g ,X UZ h o n g s h a n ,L I UJ i n gh u i (N a t i o n a lA g r i c u l t u r a lR e s e a r c hO u t s t a n d i n g T a l e n t s a n dT h e i r I n n o v a t i o nT e a m /I n n e rM o n g o l i aG r a s s l a n dT a l e n t s I n n o v a t i o n T e a m /O a tW h o l e I n d u s t r y C h a i nS c i e n c e a n dT e c h n o l o g y I n n o v a t i o nT e a m /O a tE n g i n e e r i n g R e s e a r c hC e n t e r o f I n n e rM o n go l i a U n i v e r s i t y /O a tE n g n e e r i n g L a b o r a t o r y o f F n n e rM o n g o l i aA u t o n o m o u sR e gi o n /C o l l a b o r a t i v e I n n o v a t i o nC e n t e r o fM u l t i -G r a i n I n d u s t r y I n n e rM o n g o l i aA g r i c u l t u r a lU n i v e r s i t y ,H o h h o t ,I n n e rM o n go l i a 010019,C h i n a )A b s t r a c t :T o i n v e s t i g a t e t h e e f f e c t o f e x o g e n o u s γ-a m i n o b u t yr i c a c i d (G A B A )o n t h e s a l t -a l k a l i n e t o l e r -a n c e o f o a t s ,a no a tv a r i e t y B a i y a n2w a su s e da s t h e t e s tm a t e r i a l ,a n dd i f f e r e n tc o n c e n t r a t i o n so f G A B A w e r es p r a y e do nt h el e a v e su n d e r m i x e ds a l t -a l k a l i n es t r e s s (N a C l ʒN a 2S O 4ʒN a H C O 3ʒN a 2C O 3mo l a r r a t i oo f 1ʒ9ʒ9ʒ1).T h ec h a n g e s i nc h l o r o p h y l l c o n t e n t ,f l u o r e s c e n c e p a r a m e t e r s ,o s m o r e g u l a t o r y s u b s t a n c e s a n d a n t i o x i d a n t e n z y m e a c t i v i t i e s o f o a t s e e d l i n gsw e r em e a s u r e d ,a n d t h e g r o w t hm i t i g a t i o n e f f e c t o f s e e d l i n g sw a s a l s o c o m p r e h e n s i v e l y ev a l u a t e d .T h e r e s u l t s s h o w e d t h a t e x -o g e n o u s s p r a y i n g o f 4-6mm o l ㊃L -1G A B As i g n i f i c a n t l y i n c r e a s e d t h e c h l o r o p h yl l c o n t e n t a n d p h o t -o s y s t e mI I r e a c t i o na c t i v i t y o f o a t s e e d l i n g su n d e r s a l i n e -a l k a l i s t r e s s ,a n d p r o m o t e d t h e i r p h o t o s yn -t h e s i s .U n d e r s a l i n e -a l k a l i s t r e s s ,c o m p a r e dw i t hs p r a y i n g wa t e r ,t h ec o n t e n to f p r o l i n e (P r o ),m a -l o n d i a l d e h y d e(M D A)a n d s o l u b l e s u g a r(S S)o f o a t s e e d l i n g s s p r a y e dw i t hd i f f e r e n t c o n c e n t r a t i o n so f G A B Ad e c r e a s e db y14.7%-29.7%,28.2%-54.4%a n d1.8%-11.8%,r e s p e c t i v e l y,a n dt h ec o n t e n t o f s u p e r o x ide d i s m u t a s e(S O D),p e r o x i d a s e(P O D)a n d c a t a l a s e(C A T)i n c r e a s e db y17.9%-58.3%,4.4%-33.4%a n d8.3%-19.1%,r e s p e c t i v e l y.T h r o u g hc o m p r e h e n s i v ee v a l u a t i o nu s i n g t h em e m b e r s h i p f u n c t i o n m e t h o d,i tw a s f o u n dt h a t t h eo p t i m a l c o n c e n t r a t i o nf o r f o l i a r s p r a y i n g o f G A B At o i m p r o v e s a l t-a l k a l i n e t o l e r a n c e o f o a t s e e d l i n g sw a s6mm o l㊃L-1.T h u s,t h em o d e r a t e c o n-c e n t r a t i o no fG A B Ac a n i m p r o v e t h es a l t-a l k a l i n e t o l e r a n c eo fo a t s e e d l i n g sb y i n c r e a s i n gp h o t o s y n-t h e t i c c a p a c i t y a n da n t i o x i d a n te n z y m ea c t i v i t i e sa n dd e c r e a s i n g t h ec o n t e n to fo s m o r e g u l a t o r y s u b-s t a n c e s,w h i c h c a n e f f e c t i v e l y a l l e v i a t e t h e i n h i b i t o r y e f f e c t o f s a l t-a l k a l i n e s t r e s s o n s e e d l i n gg r o w t h. K e y w o r d s:G a mm a-a m i n o b u t y r i c a c i d;O a t s;S a l t-a l k a l i s t r e s s;P h y s i o l o g i c a l e f f e c t土壤盐碱化严重影响作物生产,是限制作物产量和品质提高的主要非生物胁迫之一[1]㊂盐碱胁迫会造成渗透胁迫㊁低氧胁迫和离子毒害,使植物光合作用受阻[2],影响其吸水性,引起大量活性氧积累,最终导致植物组织衰老或死亡[3-4]㊂燕麦是中国北方地区重要的优势特色作物[5],在内蒙古种植面积和总产量居全国首位[6]㊂作为盐碱地先锋作物,在轻㊁中度盐碱化耕地种植㊁推广,对充分利用与改良盐碱化耕地,促进当地农民收入及经济发展,都有极其重要的意义[7-8]㊂因此,提高燕麦耐盐碱性是解决其生产受限的途径之一㊂目前,外源植物生长调节剂可以有效缓解非生物胁迫对植物的伤害㊂γ-氨基丁酸(G A B A)是一种以自由态存在于各种生物中的四碳非蛋白质氨基酸[9],在植物生长发育和抗性反应中发挥着重要作用[10],G A B A积累可以缓解胁迫带来的伤害[11]㊂外源G A B A在逆境条件下不仅可以通过提高植物体中保护酶的活性来减轻活性氧对植物体的伤害,还能从调节胞内渗透压㊁光合作用等方面提高作物的抗逆性㊂有报道指出,添加0.5 mm o l㊃L-1G A B A对促进N a C l胁迫下垂穗披碱草种子萌发和幼苗生长效果最佳[12]㊂韩多红等[13]发现盐胁迫下叶面喷施3~12mm o l㊃L-1 G A B A均可降低菘蓝幼苗中R O S物质积累,抗氧化酶活性增强,进而使其耐盐性提高㊂在外源G A B A的作用下,不同耐性甜瓜受到的膜脂过氧化伤害被缓解,保证了光合结构的正常生理功能,增强了其光合能力,且叶面喷施50mm o l㊃L-1 G A B A有利于提高幼苗对逆境的适应能力[14-15]㊂可见,逆境条件下不同作物对外源G A B A的响应存在差异,但有关外源G A B A对燕麦幼苗抵抗盐碱胁迫能力的研究尚未见报道㊂因此,本试验研究混合盐碱胁迫下,叶面喷施不同浓度G A B A对燕麦幼苗生长的缓解效应,旨在分析外源G A B A 对燕麦幼苗盐碱耐受性的保护作用,筛选适宜喷施浓度,为燕麦耐盐碱性栽培及盐碱地利用提供理论与实践依据㊂1材料与方法1.1试验材料及地点供试材料为白燕2号,是我国北方地区燕麦主栽品种之一,具有耐盐碱特性,由吉林省白城农业科学院提供㊂本试验于2022年在内蒙古农业大学燕麦产业研究中心温室进行;γ-氨基丁酸采购于上海麦克林生化科技股份有限公司㊂1.2试验方法使用装有沙子和珍珠岩的塑料盆(直径27 c m,高18c m),先用霍格兰营养液浇透,2d后播种,每盆播30粒,之后定苗20株,温度(20ʃ5)ħ,定期浇灌霍格兰营养液,待幼苗两叶一心时(20d)做如下6个处理:(1)对照(C K),霍格兰营养液+叶面喷施清水;(2)200mm o l㊃L-1盐碱溶液(N a C lʒN a2S O4ʒN a H C O3ʒN a2C O3摩尔比为1ʒ9ʒ9ʒ1,p H=8.7)+叶面喷施清水;(3)200mm o l㊃L-1盐碱溶液+2mm o l㊃L-1G A B A;(4)200m m o l㊃L-1盐碱溶液+4m m o l㊃L-1G A B A;(5)200mm o l㊃L-1盐碱溶液+6 mm o l㊃L-1G A B A;(6)200mm o l㊃L-1盐碱溶液+8mm o l㊃L-1G A B A㊂每个处理重复3次㊂为避免盐激反应,分3次加入盐碱溶液至200 mm o l㊃L-1,每次加入混合盐碱溶液间隔为24 h,每盆浇灌量为300m L㊂叶面喷施在胁迫处理后第1天开始,连续喷施4d,喷施液采用手持式喷雾器进行叶面喷施处理,于每天18:00喷施,为增加喷施液与幼苗叶片的粘附性,喷施液中加0.01%的吐温-80,喷施量为15m L㊂喷施处理结束后第㊃322㊃第2期张碧茹等:外源γ-氨基丁酸缓解燕麦幼苗盐碱胁迫的生理效应7天进行S P A D值测定,之后取新鲜叶片0.5g 用于叶片相对含水量测定,剩余新鲜叶片液氮速冻后,于-80ħ超低温冰箱保存备用,用于生理指标测定㊂1.3测定指标与方法1.3.1叶绿素相对含量的测定S P A D值采用S P A D-502叶绿素仪于上午10:00,按S P A D数值表征,每片叶测定叶尖㊁叶中㊁叶基共3个部位,取平均值;叶绿素a及b㊁类胡萝卜素采用分光光度法测定,测定波长分别为665㊁649和470n m,前处理将叶片用95%的乙醇研磨,25m L定容遮光保存[16]㊂1.3.2叶绿素荧光参数的测定用F M S-2便携式脉冲调制式荧光仪测定叶绿素荧光参数㊂先测定光下最大荧光(F m')㊁稳态荧光(F s)和光下最小荧光(F0'),然后将同部位幼苗叶片暗适应20m i n,测定初始荧光(F0)㊁最大荧光(F m),通过以上测定的叶绿素荧光参数计算出:P SⅡ最大光能转换效率F v/F m=(F m -F0)/F m;实际光化学效率ΦP SⅡ=(F m'-F s)/F m';光化学淬灭系数q P=(F m'-F s)/(F m'-F0');非光化学淬灭系数N P Q=(F m-F m')/F m'[17]㊂1.3.3生理指标的测定叶片相对含水量(RW C)采用烘干法测量[18];丙二醛(M D A)含量测定用硫代巴比妥酸(T B A)法[19];脯氨酸(P r o)含量测定用酸性茚三酮法[20];可溶性糖(S S)和可溶性蛋白(S P)含量的测定分别用蒽酮比色法和考马斯亮蓝染色法[18];超氧化物歧化酶(S O D)㊁过氧化物酶(P O D)活性测定分别用氮蓝四唑(N B T)法[21]和愈创木酚法[22];过氧化氢酶(C A T)活性测定采用过氧化氢法[23]㊂1.4数据处理采用E x c e l2019处理数据和制图,用S P S S26.0软件进行单因素方差(A N O V A)分析,并用D u n c a n法进行多重比较,差异显著性水平均为P<0.05,各指标数据均为3个重复的平均值ʃ标准偏差㊂参考王苗苗等[24]的方法,利用主成分分析将外源G A B A对盐碱胁迫下燕麦幼苗生长的相关指标降维,筛选出耐盐碱性综合指标,并计算出综合指标权重,最后采用隶属函数法进行外源G A B A 对盐碱胁迫下燕麦幼苗生长缓解效应的综合评价㊂2结果与分析2.1外源G A B A对盐碱胁迫下燕麦幼苗S P A D 值和叶绿素含量的影响盐碱胁迫(Y)处理下,燕麦幼苗S P A D值和叶绿素a㊁b及类胡萝卜素含量较C K均降低(表1),分别下降了10.9%㊁20.7%㊁14.3%和26.2%,随着叶面喷施G A B A浓度变化呈先上升后下降的趋势,在4mm o l㊃L-1处理时增幅最高,此处理下S P A D值㊁叶绿素a㊁b及类胡萝卜素含量较盐碱胁迫处理分别上升了10.0%㊁30.4%㊁41.7%和22.9%㊂2.2外源G A B A对盐碱胁迫下燕麦幼苗荧光特性的影响从表2可以看出,与C K相比,盐碱胁迫(Y)下燕麦幼苗叶片光反应系统P SⅡ最大光能转换效率(F v/F m)显著降低了6.8%(P<0.05),非光化学淬灭系数(N P Q)显著升高了34.6%,实际光化学效率(ΦP SⅡ)和光化学淬灭系数(q P)均下表1外源G A B A对盐碱胁迫下燕麦幼苗S P A D值和叶绿素含量的影响T a b l e1E f f e c t s o f e x o g e n o u sG A B Ao n c h l o r o p h y l l c o n t e n t o f o a t s e e d l i n g s u n d e r s a l i n e-a l k a l i s t r e s s处理T r e a t m e n t S P A D叶绿素aC h l o r o p h y l l a/(m g㊃g-1)叶绿素bC h l o r o p h y l l b/(m g㊃g-1)类胡萝卜素C a r o t e n o i d/(m g㊃g-1)C K35.9ʃ0.7a0.29ʃ0.01a0.14ʃ0.02a b0.65ʃ0.04aY32.0ʃ0.7b0.23ʃ0.04b0.12ʃ0.02b c0.48ʃ0.01b cG132.3ʃ1.2b0.21ʃ0.02b0.13ʃ0.02b c0.44ʃ0.09cG235.2ʃ1.3a0.30ʃ0.04a0.17ʃ0.02a0.59ʃ0.10a bG335.3ʃ1.2a0.23ʃ0.0b0.13ʃ0.01b0.54ʃ0.08a b cG432.8ʃ1.2b0.22ʃ0.01b0.10ʃ0.0c0.51ʃ0.11a b cC K:对照;Y㊁G1㊁G2㊁G3和G4,分别为盐碱胁迫条件下喷施清水㊁2mm o l㊃L-1G A B A㊁4mm o l㊃L-1G A B A㊁6mm o l㊃L-1G A B A 和8mm o l㊃L-1G A B A㊂不同小写字母表示在不同处理下相同指标差异显著(P<0.05),下同㊂C K:C o n t r o l;Y,G1,G2,G3,a n dG4r e p r e s e n t s p r a y i n g w a t e r,2mm o l㊃L-1G A B A,4mm o l㊃L-1G A B A,6mm o l㊃L-1G A-B A,a n d8mm o l㊃L-1G A B Au n d e r s a l i n e-a l k a l i s t r e s s.D i f f e r e n t n o r m a l l e t t e r s i n d i c a t e s i g n i f i c a n t d i f f e r e n c e s f o r t h e s a m e i n d i c a t o r s u n d e r d i f f e r e n t t r e a t m e n t s(P<0.05).T h e s a m e i n t a b l e s2-4.㊃422㊃麦类作物学报第44卷表2 外源G A B A 对盐碱胁迫下燕麦幼苗叶绿素荧光特性的影响T a b l e 2E f f e c t s o f e x o g e n o u sG A B Ao n c h l o r o p h y l l c o n t e n t o f o a t s e e d l i n gs u n d e r s a l i n e -a l k a l i s t r e s s 处理T r e a t m e n tP S Ⅱ最大光能转换效率M a x i m u m p h o t o c h e m i c a le f f i c i e n c y (F v /F m)P S Ⅱ实际光化学效率A c t u a l ph o t o c h e m i c a l e f f i c i e n c y o f P S Ⅱ(ΦP SⅡ)光化学淬灭系数P h o t o c h e m i c a lq u e n c h (qP )非光化学淬灭系数N o n e p h o t o c h e m i c a lqu e n c h (N P Q )C K 0.819ʃ0.001a b 0.758ʃ0.005a 0.970ʃ0.004a 0.125ʃ0.014c d Y0.763ʃ0.006c 0.751ʃ0.011a 0.963ʃ0.023a 0.191ʃ0.016a G 10.814ʃ0.002b 0.753ʃ0.006a 0.968ʃ0.003a 0.169ʃ0.018b G 20.818ʃ0.005a b 0.761ʃ0.007a 0.969ʃ0.004a 0.141ʃ0.013c G 30.824ʃ0.005a0.762ʃ0.013a 0.969ʃ0.004a 0.109ʃ0.009d G 40.819ʃ0.006a b0.751ʃ0.013a0.966ʃ0.008a0.118ʃ0.009d降但不显著㊂与盐碱胁迫(Y )相比,不同浓度G A B A 处理后燕麦幼苗叶片光反应系统P SⅡF v /F m ㊁ΦP SⅡ和q P 均得到了提高,N P Q 均显著降低,荧光特性在6mm o l ㊃L -1处理下改善效果最为明显㊂2.3 外源G A B A 对盐碱胁迫下燕麦幼苗叶片相对含水量和渗透调节物质含量的影响叶片相对含水量可以反应作物在压力下的水分状态和保水能力㊂由图1可知,与C K 相比,盐碱胁迫(Y )处理下,燕麦幼苗的叶片相对含水量显著降低,在叶面喷施不同浓度G A B A 后叶片相对含水量均增加,分别上升了6.4%㊁10.6%㊁10.2%和4.9%,在4和6mm o l ㊃L -1处理时较盐碱胁迫处理差异达到显著水平㊂由图2可知,与C K 相比,盐碱胁迫(Y )下燕麦幼苗叶片的脯氨酸㊁丙二醛和可溶性蛋白含量均显著升高,分别增长39.4%㊁27.6%和3.2%,可溶性糖含量升高了1.6%,但差异不显著㊂喷施不同浓度G A B A 处理后P r o ㊁M D A 和可溶性糖含量均呈先下降后上升的趋势,可溶性蛋白含量呈下降趋势㊂与盐碱胁迫(Y )相比,在不同浓度G A B A 处理中,P r o 和可溶性糖含量以6mm o l ㊃L -1处理时缓解效果最为显著,分别降低了29.7%和11.8%,M D A 含量则以4mm o l㊃L -1处理时缓解最为显著,降低了54.4%㊂图1 外源G A B A 对盐碱胁迫下燕麦幼苗叶片相对含水量的影响F i g .1 E f f e c t o f e x o g e n o u sG A B Ao n t h e r e l a t i v ew a t e r c o n t e n t i no a t s e e d l i n gl e a v e s u n d e r s a l i n e -a l k a l i s t r e s s 2.4 外源G A B A 对盐碱胁迫下燕麦幼苗抗氧化酶活性的影响与C K 相比,盐碱胁迫(Y )处理下燕麦幼苗叶片的S O D ㊁P O D 和C A T 活性显著升高(图3),分别增加了73.3%㊁5.6%和16.3%;不同浓度G A B A 处理后S O D ㊁P O D 和C A T 活性则表现为先升后降,且S O D 和P O D 活性均在6mm o l ㊃L -1G A B A 处理时达到峰值,C A T 活性在4mm o l ㊃L -1G A B A 处理时达到峰值,较盐碱胁迫处理分别上升了58.3%㊁33.4%和19.1%㊂图2 外源G A B A 对盐碱胁迫下燕麦幼苗叶片渗透调节物质的影响F i g .2 E f f e c t s o f e x o g e n o u sG A B Ao no s m o t i c r e g u l a t o r y s u b s t a n c e s i no a t s e e d l i n gl e a v e s u n d e r s a l i n e -a l k a l i s t r e s s ㊃522㊃第2期张碧茹等:外源γ-氨基丁酸缓解燕麦幼苗盐碱胁迫的生理效应图3 外源G A B A 对盐碱胁迫下燕麦幼苗叶片抗氧化酶活性的影响F i g .3 E f f e c t s o f e x o g e n o u sG A B Ao na n t i o x i d a n t e n z y m e a c t i v i t i e s o f o a t s e e d l i n gl e a v e s u n d e r s a l i n e -a l k a l i s t r e s s 2.5 综合评价采用主成分分析法,将盐碱胁迫下燕麦幼苗叶片相对含水量㊁叶绿素含量㊁荧光特性㊁渗透调节物质㊁抗氧化系统等指标分为了3个主成分(表3)㊂其中,第1主成分各指标系数较大的是脯氨酸㊁丙二醛㊁P S Ⅱ实际光化学效率㊁最大光能转换效率㊁非光化学淬灭系数㊁光化学淬灭系数㊁可溶性糖㊁超氧化物歧化酶㊁过氧化物酶和类胡萝卜素,特征值为7.602,贡献率为47.51%;第2主成分各指标系数较大的是可溶性蛋白㊁S P A D 值㊁叶绿素a ,特征值为4.257,贡献率为26.61%;第3主成分各指标系数较大的是叶片相对含水量和过氧化氢酶,特征值为2.275,贡献率为14.22%㊂利用隶属函数法对外源G A B A 缓解盐碱胁迫效应进行综合评价(表4)得出,在G 3(6mm o l ㊃L -1G A B A )处理对燕麦幼苗缓解盐碱胁迫的效果最佳,综合评价结果为:G 3>G 2>G 1>G 4>C K>Y ㊂表3 各综合指标系数及贡献率T a b l e 3 C o m pr e h e n s i v e i n d e x c o e f f i c i e n t a n d c o n t r i b u t i o n r a t e 指标I n d e x 主成分1P r i n c i p a l c o m po n e n t 1主成分2P r i n c i p a l c o m po n e n t 2主成分3P r i n c i p a l c o m po n e n t 3RW C-0.0740.5250.810S P A D 0.5830.790-0.038C h l o r o p h yl l a 0.5960.6460.232C h l o r o p h y l l b 0.362-0.324-0.567C a r o t e n o i d 0.6860.617-0.224F v /F m0.826-0.169-0.381ΦP SⅡ0.9000.1590.195qP 0.7130.442-0.213N P Q-0.8260.1690.381P r o -0.924-0.2730.162M D A -0.9210.173-0.115S S-0.7870.5850.018S P-0.129-0.934-0.190S O D0.697-0.5560.438P O D0.697-0.5560.438C A T0.555-0.4890.598特征值E i ge nv a l u e 7.6024.2572.275贡献率C o n t r i b u t i o n/%47.5126.6114.22累计贡献率C u m u l a t i v e c o n t r i b u t i o n/%47.5174.1288.34㊃622㊃麦 类 作 物 学 报 第44卷表4不同处理各综合指标隶属函数值㊁权重㊁D值及盐碱胁迫缓解效应评价T a b l e4M e m b e r s h i p f u n c t i o nv a l u e,w e i g h t,D v a l u e o f e a c h c o m p r e h e n s i v e i n d e xu n d e rd i f fe r e n t t r e a t m e n t s a n d e v a l u a t i o nof s a l i n e-a l k a l i s t r e s sm i t ig a t i o n e f f e c t处理T r e a t m e n t主成分1P r i n c i p a lc o m p o n e n t1主成分2P r i n c i p a lc o m p o n e n t2主成分3P r i n c i p a lc o m p o n e n t3U(X1)U(X2)U(X3)D值D v a l u e综合评价C o m p r e h e n s i v ee v a l u a t i o nC K-1.8763.2530.4640.4440.4350.4500.4435Y1.3611.116-3.9580.4170.4910.5200.4566 G1-0.038-1.647-2.2450.5450.4170.3470.4753 G21.4180.1142.1570.4670.6560.5010.5292 G30.912-0.2533.5250.5950.6350.4460.5831 G4-1.778-2.5830.0570.3730.5540.6440.4714权重W e i g h t0.5380.3010.1613讨论叶片中光合色素主要包括叶绿素和类胡萝卜素,是反映植物光合能力的一个重要指标,且叶绿素含量直接影响叶绿体对光能的捕获与转化[25]㊂本试验发现,盐碱胁迫下燕麦幼苗S P A D值㊁叶绿素含量均下降,而叶面喷施4mm o l㊃L-1G A-B A后S P A D值和叶绿素含量明显增加,陈光鑫等的试验也得到类似结果[26],说明叶绿体结构在胁迫时遭到破坏,使叶绿素的合成与降解的动态平衡被打破,外源喷施G A B A后对叶绿体起到了保护作用㊂但是前人在甜瓜[15,27]的试验中发现,短期C a(N O3)2胁迫会使光合色素升高,喷施G A B A后则降低,可能是短期盐碱胁迫下植物产生的相对 浓缩 效应㊂可见,胁迫时长不同光合色素合成与降解规律也不一致,但G A B A缓解胁迫对植物生长的抑制作用效果均表现为有利㊂叶绿素荧光参数对环境逆境胁迫反应敏感,可反映环境因子对植物光合生理状况的影响[28]㊂盐碱胁迫后光系统Ⅱ活性中心受到伤害,光能利用率降低,使叶片光合受抑制,从而造成叶绿素荧光参数的下降㊂在本试验中,盐碱胁迫下不同浓度G A B A处理后燕麦幼苗叶片光反应系统P SⅡF v/F m㊁ΦP SⅡ和q P均得到了提高,N P Q均显著降低,与王日明等[29]的研究结果一致,表明外源施加G A B A可提高光系统Ⅱ反应中心的光能转换效率㊁潜在活性和开放比例,同时增强了过剩光能的耗散,减轻胁迫对光合的抑制与光合器官造成的损伤,提高盐碱胁迫下燕麦幼苗的光合能力和耐盐碱性㊂G A B A可作为小分子渗透调节物质,可降低细胞质水势,增强细胞的保水性,从而缓解细胞缺水造成的伤害[30-31]㊂本试验结果显示,盐碱胁迫下燕麦幼苗的叶片相对含水量降低,在叶面喷施G A B A后叶片相对含水量提高,有效缓解了胁迫出现的生理性失水㊂渗透调节物质作为植物体内应对逆境胁迫诱导积累的重要信号物质[32],在盐碱胁迫下,植物体内产生渗透胁迫,自身通过积累更多的渗透调节物质来缓解盐胁迫引发的渗透胁迫㊂本研究结果表明,在盐碱胁迫下,燕麦幼苗脯氨酸㊁丙二醛㊁可溶性蛋白含量较C K均显著上升,主动调节渗透平衡,从而缓解盐碱胁迫带来的伤害;而在叶面喷施不同浓度G A B A后燕麦幼苗脯氨酸㊁丙二醛和可溶性糖含量均呈 先降后升 的趋势㊂宋建超等[12]研究发现,外源G A B A处理后盐碱胁迫下垂穗披碱草幼苗可溶性糖含量变化趋势同本研究结果一致㊂还有研究结果显示,在高浓度盐胁迫下外源G A B A处理后西伯利亚白刺幼苗的可溶性糖和脯氨酸含量呈 先升后降 的趋势[33]㊂以上研究说明,盐碱胁迫下植物会通过调节自身渗透调节物质来缓解胁迫损伤,外源G A B A可使植株脯氨酸㊁丙二醛㊁可溶性糖等渗透调节物质积累,提高其抗逆性㊂植物在正常生长条件下,体内活性氧(R O S)的产生与清除处于动态平衡,且不会对细胞膜造成伤害,当处在低温㊁高温㊁干旱和盐碱等逆境时,这种动态平衡被打破,造成R O S的大量积累,进而对细胞造成不同程度的氧化伤害,同时植物体内会启动自身的抗氧化酶系统,以此来清除过多的R O S,增强植株抗逆性[34-35]㊂植物体内常见的抗氧化酶为S O D㊁P O D和C A T,它们的活性可以直接反映植物耐逆境胁迫的能力㊂本试验中,盐碱胁迫处理后燕麦幼苗的S O D㊁P O D和C A T活性均显著上升,说明盐碱胁迫造成了幼苗生长过㊃722㊃第2期张碧茹等:外源γ-氨基丁酸缓解燕麦幼苗盐碱胁迫的生理效应程中氧化损伤,燕麦自身可以通过提高抗氧化酶活性以降低盐碱胁迫的伤害㊂有研究指出,G A-B A可通过调控植物的抗氧化防御系统来缓解其逆境胁迫[36]㊂赵宏伟等[37]研究证实外源G A B A 可提高抗氧化酶活性,降低氧化损伤㊂在葛甜甜等[38]的研究中发现,在盐和碱胁迫中,添加0.05和0.2~0.3mm o l㊃L-1的G A B A可显著提高S O D㊁P O D和C A T活性㊂本研究结果显示,在盐碱胁迫下叶面喷施4~6mm o l㊃L-1G A B A处理后,燕麦幼苗S O D㊁P O D和C A T活性变化与前人研究结果一致㊂因此,盐碱胁迫下,外源施加G A B A与S O D㊁P O D和C A T活性强相关,进一步说明外源G A B A可促使植物产生更多的抗氧化酶活性来抵御盐碱胁迫对幼苗生长的伤害㊂4结论盐碱胁迫抑制燕麦幼苗生长,叶面喷施适宜浓度的G A B A可显著提高燕麦幼苗在盐碱胁迫下的S P A D值㊁叶绿素含量㊁荧光特性,降低渗透调节物质含量,促进S O D㊁P O D㊁C A T活性,从而缓解盐碱胁迫对燕麦幼苗生长的抑制作用㊂在本试验中,盐碱胁迫下叶面喷施6mm o l㊃L-1G A-B A对于提高燕麦幼苗的盐碱抗性效果最优㊂参考文献:[1]樊自立,马英杰,马映军.中国西部地区的盐渍土及其改良利用[J].干旱区研究,2001,18(3):2.F A NZL,MA YJ,MA YJ.S 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Journal of Membrane Science 376 (2011) 196–206Contents lists available at ScienceDirectJournal of MembraneSciencej o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /m e m s ciFouling and cleaning of RO membranes fouled by mixtures of organic foulants simulating wastewater effluentWui Seng Ang 1,Alberto Tiraferri,Kai Loon Chen 2,Menachem Elimelech ∗Department of Chemical and Environmental Engineering,P.O.Box 208286,Yale University,New Haven,CT 06520-8286,USAa r t i c l e i n f o Article history:Received 6December 2010Received in revised form 7April 2011Accepted 9April 2011Available online 20 April 2011Keywords:Reverse osmosis FoulingWastewater effluent CleaningOrganic foulantsWastewater treatment Effluent organic matter Wastewater reclamation Membranesa b s t r a c tThe fouling and subsequent cleaning of RO membranes fouled by a mixture of organic foulants sim-ulating wastewater effluent has been systematically investigated.The organic foulants investigated included alginate,bovine serum albumin (BSA),Suwannee River natural organic matter,and octanoic acid,representing,respectively,polysaccharides,proteins,humic substances,and fatty acids,which are ubiquitous in effluent organic matter.After establishing the fouling behavior and mechanisms with a mixture of organic foulants in the presence and absence of calcium ions,our study focused on the clean-ing mechanisms of RO membranes fouled by the mixture of organic foulants.The chemical cleaning agents used included an alkaline solution (NaOH),a metal chelating agent (EDTA),an anionic surfactant (SDS),and a concentrated salt solution (NaCl).Specifically,we examined the impact of cleaning agent type,cleaning solution pH,cleaning time,and fouling layer composition on membrane cleaning effi-ciency.Foulant–foulant adhesion forces measured under conditions simulating chemical cleaning of a membrane fouled by a mixture of the investigated organic foulants provided insights into the chemical cleaning mechanisms.It was shown that while alkaline solution (NaOH)alone is not effective in dis-rupting the complexes formed by the organic foulants with calcium,a higher solution pH can lead to effective cleaning if sufficient hydrodynamic shear (provided by crossflow)prevails.Surfactant (SDS),a strong chelating agent (EDTA),and salt solution (NaCl)were effective in cleaning RO membranes fouled by a mixture of foulants,especially if applied at high pH and for longer cleaning times.The observed cleaning efficiencies with the various cleaning agents were consistent with the related measurements of foulant–foulant intermolecular forces.Furthermore,we have shown that an optimal cleaning agent con-centration can be derived from a plot presenting the percent reduction in the foulant–foulant adhesion force versus cleaning agent concentration.© 2011 Elsevier B.V. All rights reserved.1.IntroductionAs demand for potable water increases worldwide,the paradigm for selecting water sources to meet this demand is transitioning from conventional sources,such as reservoirs and lakes,to less con-ventional sources,such as treated secondary wastewater effluent.In order to produce water of superior quality,the use of mem-branes in desalination and wastewater reclamation has become more widespread.Membrane fouling is a major impediment to the use of membrane technology for such applications,because fouling is inevitable.Despite research efforts to develop better anti-fouling membranes [1]and improved fouling-control strategies [2,3],membrane fouling still occurs over time.Thus,a long-term∗Corresponding author.Tel.:+12034322789;fax:+12034324387.E-mail address:menachem.elimelech@ (M.Elimelech).1Current address:Public Utility Board of Singapore,Singapore.2Current address:Department of Geography and Environmental Engineering,Johns Hopkins University,Baltimore,MD 21218,United States.solution would be to remove the foulant deposited on the mem-brane via chemical cleaning.To select the appropriate cleaning agents and adopt an effective chemical cleaning protocol for fouled membranes in wastewater reclamation,the implications of wastewater effluent characteris-tics on membrane fouling have to be well-understood.Wastewater effluent contains dissolved organic matter,commonly known as effluent organic matter (EfOM),which comprises polysaccha-rides,proteins,aminosugars,nucleic acids,humic and fulvic acids,organic acids,and cell components [2–4].Organic fouling of the RO membranes by the EfOM can be extensive since EfOM is gener-ally small enough to pass through the pores of pretreatment (MF or UF)membranes [4].In particular,recent findings suggest that while biofouling can prevail on the tail-element of the membrane module,fouling of the lead-element exposed to reclaimed water is dominated by EfOM adsorption [5].In addition,higher potential of fouling was observed for the higher molecular weight hydropho-bic/aromatic fraction of the EfOM [6,7].The presence of Ca 2+in the feed source for the RO membranes has been reported to form complexes with the constituents of EfOM,such as polysaccharidesW.S.Ang et al./Journal of Membrane Science376 (2011) 196–206197[8]and natural organic matter[9],and to significantly enhance membrane fouling.While our previous studies have addressed the fouling of RO membranes by individual organic foulant types,such as polysaccharides[10],proteins[11],and fatty acids[12],only recently have investigations reported on the effects of a combina-tion or mixture of foulants on the fouling of RO membranes[13,14].A variety of chemical cleaning agents are commonly used to clean RO membranes fouled by organic matter[15].Alkaline solutions remove organic foulants on membranes by hydroly-sis and solubilization of the fouling layer.Alkaline solutions also increase the solution pH,and,therefore,increase the negative charges and solubility of the organic foulant.Metal chelating agents remove divalent cations from the complexed organic molecules and weaken the structural integrity of the fouling layer matrix[16]. Surfactants solubilize macromolecules by forming micelles around them[17],thereby facilitating removal of the foulants from the membrane surface.In our earlier study on salt cleaning of organic matter-fouled RO membranes[18],we demonstrated that NaCl and other common inert salts can be used as an effective alternative for the cleaning of RO membranes fouled by gel-forming hydrophilic organic foulants.In the presence of a salt solution,the fouling layer swells and becomes more porous.As a result,this would facil-itate the diffusion of Na+into the fouling layer and breakup of Ca2+–alginate bonds by ion exchange.Understanding the fouling layer characteristics and the interaction of chemical agents with foulants is therefore critical for the effective cleaning of organic matter-fouled RO membranes.Atomic force microscopy(AFM)has been applied in mem-brane fouling/cleaning research to quantify intermolecular forces [10,19–21].Our research has shown that foulant–foulant inter-actions could be determined by performing force measurements using a carboxylate-modified latex colloid probe in an AFMfluid cell[10,20].The technique has been used to quantify the foul-ing behavior of a nanofiltration membrane fouled by humic acid and the cleaning efficiencies of EDTA and SDS[20],and has been extended to quantify RO membrane fouling by organic foulant in the form of alginate[10],BSA[11],and octanoic acid[12].In this study,the AFM has also been employed as an alternative tool to indicate the optimal concentration of cleaning agent for cleaning fouled membranes.The original protocol[11,12]for using the AFM has been modified to investigate the intermolecular adhesion force between different foulants.The objective of this study is to explore the mechanisms govern-ing the fouling of RO membranes by mixtures of organic foulants simulating wastewater effluent,and the ensuing chemical cleaning of the fouled membranes by cleaning agents.To make this study rel-evant to wastewater reclamation,we systematically investigate the fouling of RO membranes by each individual organic foulant type (polysaccharides,proteins,humic acids,or fatty acids)and mix-tures containing several types of organic foulants in the absence and presence of calcium ions.Cleaning experiments are performed with the fouled membranes using NaOH,EDTA,SDS,and NaCl as model alkaline solution,metal chelating agent,surfactant,and salt cleaning solution,respectively.The intermolecular adhesion forces between the different foulants and estimated aggregate sizes in foulant mixtures were used to explain the fouling mechanism of RO membranes and the cleaning behavior of a cleaning agent on the fouled membranes.2.Materials and methodsanic foulants Louis,MO),Suwannee River natural organic matter(SRNOM) (International Humic Substances Society,St.Paul,MN),bovine serum albumin(BSA)(Sigma–Aldrich,St.Louis,MO),and octanoic acid(OA)(Sigma–Aldrich,St.Louis,MO),respectively.According to the manufacturer,the molecular weight of the sodium alginate ranges from12to80kDa.Other characteristics of SRNOM,includ-ing molecular weight and mass fraction of hydrophobic NOM,can be found elsewhere[22,23].According to the manufacturer,the molecular weight of the BSA is about66kDa.BSA is reported to have an isoelectric point at pH4.7[24].Octanoic acid(Sigma–Aldrich,St. Louis,MO)was selected to model fatty acids in EfOM because of its presence in food and solubility in water(saturation concentration of4.7mM at20◦C)[12].Sodium alginate,BSA,and SRNOM were received in powder form,and stock solutions(2g/L)were prepared by dissolving each of the foulants in deionized(DI)water.DI water was supplied from a Milli-Q ultrapure water purification system(Millipore,Billerica, MA).Mixing of the stock solutions was performed for over24h to ensure complete dissolution of the foulants,followed byfil-tration with a0.45-␮mfilter(Durapore,Millipore,Billerica,MA). Thefiltered stock solutions were stored in sterilized glass bottles at4◦C.Octanoic acid was received in solution(≥98%concentra-tion)and was stored at room temperature.To achieve the intended octanoic acid concentration during fouling,octanoic acid was dis-solved separately for at least8h prior to fouling so that,at the initiation of fouling,octanoic acid could be introduced as a solu-tion.A few hours before the initiation of fouling,the ionic strength of the stock solution was adjusted to the same concentration as that of the feed solution(10mM)and the stock solution pH was elevated,as needed,from ambient pH of3.9–9.0by adding small amounts of1M NaOH.2.2.Chemical cleaning agentsThe chemical cleaning agents used were:NaOH(pH11.0)as an alkaline solution,certified grade disodium ethylenediaminete-traacetate(Na2–EDTA)as a metal chelating agent,certified grade sodium dodecyl sulfate(SDS)as an anionic surfactant,and NaCl as a salt cleaning solution.The agents were purchased from Fisher Sci-entific(Pittsburgh,PA)and used with no further purification.The stock chemical solutions were prepared fresh by dissolving each chemical in deionized(DI)water.The pH of the EDTA,SDS,and NaCl cleaning solutions was adjusted with1.0M NaOH as necessary.2.3.RO membraneThe relatively well-characterized thin-film composite LFC-1 membrane(Hydranautics,Oceanside,CA)was used as a model RO membrane.The average hydraulic resistance was determined to be 9.16(±0.11)×1013m−1corresponding to a hydraulic permeabil-ity of10.9(±0.13)×10−11m s−1Pa−1.The observed salt rejection was98.7–99.3%,determined with a10mM(584mg/L)NaCl feed solution at an applied pressure of300psi(2068.5kPa)and a cross-flow velocity of8.6cm/s.Membrane samples were received as dry large sheets,and were cut and stored in DI water at4◦C.The membrane has been reported to be negatively charged at solu-tion chemistries typical to wastewater effluents,with an isoelectric point at about pH4.6[25].The membrane has been reported to be coated with a neutral polyalcohol layer rich in–COH functional groups,which renders the surface less charged than the surfaces of other polyamide RO membranes without a coating layer[25,26].2.4.Crossflow test unit198W.S.Ang et al./Journal of Membrane Science376 (2011) 196–206unit consists of a membrane cell,pump,feed reservoir,temper-ature control system,and data acquisition system.The membrane cell consisted of a rectangular plate-and-frame unit,which con-tained aflat membrane sheet placed in a rectangular channel with dimensions measuring7.7cm long,2.6cm wide,and0.3cm high. Both permeate and retentate were recirculated back to the feed reservoir.Permeateflux was registered continuously by a digital flow meter(Optiflow1000,Humonics,CA),interfaced with a com-puter.Afloating disc rotameter(King Instrument,Fresno,CA)was used to monitor the retentateflow rate.The crossflow velocity and operating pressure were adjusted using a bypass valve(Swagelok, Solon,OH)in conjunction with a back-pressure regulator(U.S.Para Plate,Auburn,CA).Temperature was controlled by a recirculating chiller/heater(Model633,Polysciences)with a stainless steel coil submerged in the feed water reservoir.2.5.Fouling and cleaning experimentsThe membrane wasfirst compacted with DI water until the permeateflux became constant,followed by the initial baseline performance for1h.The membrane was then stabilized and equi-librated with a foulant-free electrolyte solution for2h.Theflux at which the baseline run was performed was predetermined so that the initialflux would drop to a specifiedflux of2.3×10−5m s−1(or 83L m−2h−1)after adding the electrolyte solution.The chemistry of the foulant-free electrolyte solution and operating conditions adjusted in this stage were similar to those used for the ensuing fouling runs.As octanoic acid takes time to dissolve completely,the mixture of organic foulant solution has to be prepared8h before the fouling run.The feed foulant solution was prepared separately in another container.The chemistry of the feed foulant solution was adjusted to be identical to that of the foulant-free electrolyte solution so that the overall ionic strength and solution chemistry would not change when the feed foulant solution was added to initiate fouling. Fouling runs were carried out for17h.At the end of the fouling run, the solution in the feed reservoir was disposed off and chemical cleaning solution was added to the feed reservoir to clean the fouled membrane.At the end of the cleaning stage,the chemical cleaning solution in the reservoir was discarded,and both the reservoir and membrane cell were rinsed with DI water toflush out the residual chemical cleaning solution.Finally,the cleaned RO membrane was subjected to the second baseline performance with DI water to re-determine the pure waterflux.The crossflow velocity throughout the experiment,except dur-ing cleaning,was maintained at8.6cm/s.The operating conditions (i.e.,initialflux,crossflow velocity,and temperature)at this stage were identical to those applied during the initial baseline perfor-mance,so as to determine the cleaning efficiency by comparing the pure waterfluxes determined before fouling and after clean-ing.Throughout all the fouling/cleaning stages,the feed water in the reservoir,which was located on top of a magnetic stirrer,was mixed rigorously to ensure complete mixing of the feed water and cleaning solution.To confirm the reproducibility of determined cleaning effi-ciency,selected fouling/cleaning runs were duplicated.Results showed that fouling rate and cleaning efficiency obtained from the duplicate runs were within less than a5%difference.To investigate the change in the permeate quality during the fouling stage,permeate samples taken before and at the start and end of fouling were analyzed for salt(NaCl)rejection using an ICP-AES(ICP Optima3000,Perkin Elmer,Waltham,MA).Permeate and feed samplings obtained before the fouling run were collected at the end were collected during thefinal40min of the fouling run.2.6.AFM adhesion force measurementsAtomic force microscopy(AFM)was used to measure the inter-facial force between the foulant in the bulk solution and the foulant in the fouling layer on the membrane.The force measurements were performed with a colloid probe,modified from a commercial-ized SiN AFM probe(Veeco Metrology Group,Santa Barbara,CA).A carboxylate modified latex(CML)particle(Interfacial Dynam-ics Corp.,Portland,OR)was used as a surrogate for the organic foulants,because organic foulants(alginate and SRNOM)carry pre-dominantly carboxylic functional groups.To make a colloid probe, a CML particle with a diameter of4.0␮m was attached using Nor-land Optical adhesive(Norland Products,Inc.,Cranbury,NJ)to a tipless SiN cantilever.The colloid probe was cured under UV light for20min.The AFM adhesion force measurements were performed in a fluid cell using a closed inlet/outlet loop.The solution chemistries of the test solutions injected into thefluid cell were identical to those used in the bench-scale fouling/cleaning experiments.Once all the air bubbles had beenflushed out of thefluid cell,the injection would stop and the outlet was closed.The membrane was equilibrated with the test solution for30–45min before force measurements were performed.The force measurements were conducted at three tofive different locations,and at least10measurements were taken at each location.Because the focus of this study was on the foulant–foulant interaction(adhesion),only the raw data obtained from the retracting force curves were processed and converted to obtain the force versus surface-to-surface separation curves.The force curves presented were the averages of all the representative force curves obtained at the different locations.The protocol for AFM analysis has been modified slightly to investigate the interaction between different foulant types. The AFM colloidal probe is soaked in organic foulant solution (2000mg/L alginate,BSA,or SRNOM,or>98%octanoic acid)for at least24h(at4◦C for alginate,BSA,and SRNOM solutions to prevent organic degradation,and at room temperature for octanoic acid). The membrane is fouled with200mg/L organic foulant(alginate, BSA,SRNOM,or octanoic acid)using the crossflow unit for about 17h.After transferring the colloidal probe to the AFMfluid cell and the membrane to the AFM disc puck,an electrolyte solution con-taining0.5mM CaCl2and8.5mM NaCl(adjusted to pH6.5±0.2) (identical solution chemistry as during fouling)is injected into the fluid cell.The volume of electrolyte solution added is just enough tofill up thefluid cell so as to minimize the possibility offlush-ing away the foulants on the membrane and probe surfaces.AFM force measurements are taken after20min of equilibration time.To investigate the effect of cleaning agent on the intermolecular adhe-sion force,the cleaning agent was added to the electrolyte solution at the same concentration as that used in the cleaning experiments.2.7.Light scatteringDynamic light scattering experiments were performed on foulant solution to determine the effective hydrodynamic diam-eters of the foulant aggregates in foulant mixtures using a multi-detector light scattering unit(ALV-5000,Langen,Germany). New glass vials(Supelco,Bellefonte,PA)for containing foulant solu-tions under various solution chemistries were cleaned prior to use by soaking overnight in a cleaning solution(Extran MA01,Merck KGaA,Darmstadt,Germany),rinsing with DI water,and drying inW.S.Ang et al./Journal of Membrane Science376 (2011) 196–206199Fig.1.Influence of individual foulant type on fouling of LFC-1membranes:(a)in the absence of Ca2+and(b)in the presence of0.5mM Ca2+.The total ionic strength of the feed solution wasfixed at10mM by adjusting with NaCl and the feed solution pH was adjusted to6.0±0.2,as necessary,by adding NaOH.Fouling conditions: foulant concentration of25mg/L,initial permeateflux of23␮m/s(or83L m−2h−1), crossflow velocity of8.6cm/s,and temperature of21.0±0.5◦C.of1M NaOH.The vial containing the foulant solution was vortexed (Mini Vortexer,Fisher Scientific)to homogenize the solution.The vial was then allowed to sit for30min before starting the light scattering experiment.All light scattering measurements were conducted by employ-ing the detector positioned at a scattering angle of90◦from the incident laser beam.The detector signal was fed into the correla-tor,which accumulated each autocorrelation function for15s.The intensity-weighted hydrodynamic radius of the colloidal aggre-gates was determined with second-order cumulant analysis(ALV software)[27].The reported size is the average of thefirst20mea-surements.3.Results and discussion3.1.Membrane fouling3.1.1.Fouling with individual foulantsFig.1presents the normalizedflux profiles for LFC-1mem-branes fouled by each individual foulant(alginate,BSA,SRNOM, or octanoic acid)in the absence(Fig.1a)and presence(Fig.1b)of Ca2+,respectively.In the absence of Ca2+,theflux decline profiles of membranes fouled by the various foulants are insignificant.The 2+Fig.2.Influence of a mixture of(a)2foulants or(b)more than2foulants on fouling of LFC-1membranes in the presence of0.5mM Ca2+.The total ionic strength of the feed solution wasfixed at10mM by adjusting with NaCl and the feed solution pH was adjusted to6.0±0.2,as necessary,by adding NaOH.Fouling conditions were identical to those in Fig.1.RO membranes by BSA,SRNOM,or octanoic acid is minimal.How-ever,we have observed that the presence of Ca2+can affect fouling behavior when the foulant concentrations are higher(300mg/L BSA;2mM or288mg/L octanoic acid)[11,12].3.1.2.Fouling with mixture of foulantsTo investigate the implications for wastewater reclamation, the effect of Ca2+on fouling of RO membranes by all possible combinations of two or more foulant types is investigated.The con-centration of each foulant type was maintained at25mg/L.Fig.2a shows the normalizedflux profiles of membranes fouled by a mix-ture of two foulants in the presence of Ca2+.The effect of Ca2+is most significant for feed solutions containing alginate as one of the two foulant types.This mechanism will be further investigated with the aid of DLS and AFM paring theflux profiles of mem-branes fouled by alginate as a co-foulant,theflux-decline profile of membrane fouled by alginate and octanoic acid is the least sig-nificant due to the formation of octanoic acid–calcium complexes, which increase the hydrophilicity of the fouling layer[12].Fig.2b shows the normalizedflux profiles of membranes fouled by a mixture of three foulant types and all foulant types in the presence of Ca2+.In the presence of Ca2+,for membranes fouled by mixtures containing alginate,the effect of Ca2+onflux profiles is most significant,especially for the membrane fouled by a mixture of alginate,BSA,and SRNOM(without octanoic acid).In compar-ing the latter with theflux profile of the membrane fouled by all200W.S.Ang et al./Journal of Membrane Science376 (2011) 196–206Fig.3.Sodium ion(Na+)rejection of RO membranes measured before,and at the start and end of the fouling runs,at an adjusted feed solution pH of6.0.The membranes were fouled by combined foulant types,composed of25mg/L each of alginate,BSA,SRNOM,and octanoic acid.Permeate and feed samples obtained before the fouling run were collected30min before the onset of fouling.Samples taken at the start of the fouling run were initiated afterfirst discarding20mL of permeate(duration of8min).Permeate and feed samples taken at the end were collected during thefinal40min of the fouling run.Error bars indicate one standard deviation.Fouling conditions were identical to those in Fig.1.contained alginate and octanoic acid in the presence of Ca2+.The inhibitory effect of octanoic acid onflux-decline profiles can also be observed by comparing theflux profile of combined foulant types of alginate,SRNOM,and octanoic acid in Fig.2b with the profile of alginate and SRNOM in Fig.2a.3.1.3.Impact of fouling on salt rejectionFig.3presents Na+rejection of the RO membranes fouled by combined foulant types of alginate,BSA,SRNOM,and octanoic acid in the presence of Ca2+,at the start and end of the fouling runs.The trend of observed Na+rejection is similar both in the absence and presence of Ca2+.At the onset of fouling,the Na+rejection instan-taneously increases.This phenomenon is consistent with previous observations,which attributed the decrease in Na+permeability to the fouling layer acting as an additional selective barrier[12]. Toward the end of the fouling runs,the fouling layer becomes thicker and denser,resulting in even higher Na+rejection.It can be inferred that the presence of Ca2+resulted in a more compact fouling layer,which improves the ability of the fouling layer to fur-ther act as a selective barrier against the transport of Na+across the membrane.3.2.Fouling mechanisms3.2.1.Role of foulant–foulant interaction and foulant sizeRecent studies have demonstrated that the long-term organic fouling of RO membranes and the consequent behavior of water flux are dominated by the feed water chemistry and strong foulant–foulant interactions[4,20,21,28].Quantifying these inter-actions provides a basis for the understanding of the fouling mechanisms and for the rational selection of a suitable cleaning strategy.As discussed in Section3.1.2,fouling behavior becomes significant when alginate is one of the co-foulants.When alginate is absent from the feed solution,regardless of the other foulant types present,fouling is relatively insignificant.This behavior can be explained by evaluating the interaction forces among the differ-ent foulants.To investigate the effect of interactions of alginate with other foulant types,DLS analysis is performed on a solution contain-ing2foulant types(200mg/L alginate plus200mg/L of another foulant type)in the presence of Ca2+.Fig.4a shows that the alginate molecules in the solution have an effective hydrodynamic diame-ter of84nm,which is larger than the effective diameter of51nm of alginate molecules in a solution in which the foulant concentration is halved.The results imply that aggregation of alginate molecules is concentration dependent.The larger effective diameter of aggre-gates formed in400mg/L alginate solution as opposed to those formed in200mg/L alginate solution also implies a more exten-sive gel network at a higher concentration.The effective diameters of the foulant molecules in mixtures of alginate and BSA,alginate and SRNOM,and alginate and octanoic acid are,respectively,48, 63,and73nm.The effective diameter is an indirect indication of the foulant size due to aggregation between the foulants.Because of the varying interactions between alginate and another foulant type in the presence of Ca2+,the aggregate size differs for foulant aggregates of different foulant combinations.Fig.4b shows the intermolecular forces between foulant adsorbed on a colloidal probe and a membrane fouled by algi-nate as determined by AFM.For a membrane fouled by alginate and octanoic acid,the dominant foulant interactions are between alginate and alginate molecules(1.03mN/m)and between octanoic acid and octanoic acid molecules(0.90mN/m).For a membrane fouled by alginate and SRNOM,the dominant foulant interaction is between alginate and alginate molecules(1.03mN/m).For a membrane fouled by alginate and BSA,the dominant foulantinter-Fig.4.(a)Effective diameter of foulant aggregates in solutions of various foulant combinations that contain alginate as co-foulant.The foulant solution consists of200mg/L alginate plus200mg/L of another foulant type in an electrolyte solution of0.5mM CaCl2and8.5mM NaCl(same solution chemistry as that used in fouling experiments).TheW.S.Ang et al./Journal of Membrane Science376 (2011) 196–206201Fig.5.Proposed structure of fouling layer on membrane surface under different combinations of foulants.actions are between alginate and alginate molecules(1.03mN/m) and between alginate and BSA molecules(0.73–0.79mN/m).We observe that when alginate is present in the feed,regardless of the co-foulant,the interaction of alginate molecules among them-selves is most dominant,with the possibility of alginate molecules interacting with other molecules,especially BSA molecules.Comparing the effective diameters of the foulant aggregates in various2-foulant mixtures(Fig.4a)with the intermolecular adhe-sion force between different foulants(Fig.4b)reveals that there is an inverse correlation between the foulant aggregate size and the intermolecular adhesion force(foulant aggregate size generally decreases as intermolecular adhesion force increases).It is hypoth-esized that the interaction among the foulant types within the aggregates would affect the conformation,and hence,the size of the aggregates in the foulant solution.For example,the relatively stronger intermolecular adhesion force between alginate and BSA molecules in the feed solution in the presence of Ca2+results in a more‘compact’or‘tighter’conformation of the foulant aggregates as compared to the foulant aggregates formed from a solution of alginate and SRNOM.The deposition of the smaller and more‘com-pact’alginate–BSA aggregates results in a tighter fouling layer and a lowerfinalflux(Fig.5)[29].We note that the SA–SA aggregate does not follow the trend of a decrease in aggregate size with increasing adhesion force because alginate molecules tend to form extended gel networks in the presence of calcium ions[29],as opposed to the other combinations of foulants.3.2.2.Proposed structure of fouling layerThe fouling experiments reveal that membrane fouling in the presence of Ca2+is controlled by alginate.From the AFM force mea-surement analysis and the DLS experiments,the proposed structure of the fouling layer when severe fouling occurs under various solu-tion chemistries is schematically shown in Fig.5.The top drawing shows the likely conformation of the cross-linked alginate fouling layer when the feed contains alginate in the presence of Ca2+.In this case,the fouling layer has the typical structure resulting from the formation of an‘egg-box’shaped gel network on the mem-brane surface[29].The middle drawing shows the proposed fouling layer formed by a feed solution containing a mixture of alginate, BSA,SRNOM,and octanoic acid(each foulant has the same concen-tration).The DLS experiments show that the aggregates of foulant mixtures containing alginate as a co-foulant have smaller effective feed solution in which alginate is the sole foulant.When the algi-nate concentration is increased while maintaining the same total foulant concentration,the fouling layer becomes more porous due to the increase in the highly ordered alginate–calcium complexes on the membrane surface.The state of the fouling layer would affect the transfer of a cleaning agent to the fouling layer,and hence,the cleaning efficiency of the cleaning agent as delineated in the next sections.3.3.Cleaning of fouled membranes3.3.1.Type of cleaning agentFig.6presents the cleaning efficiencies of various cleaning agents on membranes fouled by combined foulant types compris-ing alginate,BSA,SRNOM,and octanoic acid in the presence of 0.5mM Ca2+.Cleaning was performed for15min without an oper-ating pressure(i.e.,no permeate)and at a crossflow velocityfive times higher than that during fouling.Cleaning the fouled mem-brane with DI water resulted in19%cleaning efficiency,which implies that the fouling layer on the membrane surface was largely irreversible.Conventional cleaning agents,such as NaOH(pH11),Fig.6.Cleaning efficiencies of various cleaning agents on membranes fouled by combined foulant types comprising alginate,BSA,SRNOM,and octanoic acid,with the concentration of each foulant type at25mg/L,in the presence of0.5mM Ca2+.Cleaning conditions:time,15min;temperature,21±0.5◦C;and no applied。

食盐与人体健康课题研究范文英文回答：Salt is an essential nutrient that plays a vital role in various physiological processes in the human body. It is primarily composed of sodium and chloride ions, which are involved in maintaining fluid balance, regulating blood pressure, and facilitating nerve and muscle function.Impact of Salt on Blood Pressure.Excessive salt intake is strongly associated with elevated blood pressure, a major risk factor for cardiovascular diseases such as heart attack and stroke. Sodium ions present in salt can lead to fluid retention in the body, increasing the volume of blood in the circulatory system. This increased blood volume puts extra pressure on the blood vessel walls, resulting in hypertension.Recommendations for Salt Intake.To maintain optimal health, it is crucial to limit salt intake within recommended guidelines. The World Health Organization (WHO) recommends an upper limit of 5 grams of salt per day for adults. This amount is equivalent to approximately one teaspoon. Reducing salt intake can significantly lower blood pressure and reduce the risk of cardiovascular diseases.Alternatives to Salt for Flavoring.While it is important to limit salt intake, flavorful meals can still be enjoyed without compromising taste. Various herbs and spices, such as black pepper, garlic powder, onion powder, and oregano, can provide a wide range of flavors to dishes. Citrus fruits, such as lemons and limes, can also be used to enhance the taste of food.Health Benefits of Moderate Salt Intake.While excessive salt intake can be detrimental to health, moderate salt intake is essential for severalbodily functions. Salt helps maintain fluid balance, preventing dehydration. It also supports the proper functioning of nerves and muscles, ensuring optimal neuromuscular coordination. Additionally, salt is involved in regulating hormone production and can assist in maintaining healthy iodine levels, which is crucial for thyroid function.中文回答：食盐与人体健康。

耐盐碱作物品种选育英文回答：Salt-alkali tolerance is an important trait for crop varieties, especially in regions with high soil salinity and alkalinity. Developing salt-alkali tolerant crop varieties is crucial to ensure food security and sustainable agriculture. The selection and breeding ofsalt-alkali tolerant crop varieties require specificcriteria to be met.Firstly, salt-alkali tolerant crop varieties should have the ability to withstand high salt concentrations in the soil. This means that they should have mechanisms to exclude or compartmentalize salt ions, preventing them from accumulating in the plant tissues. For example, some crop varieties have developed salt glands on their leaves to excrete excess salt, while others have efficient ion transporters that can regulate the uptake and distribution of salt ions within the plant.Secondly, salt-alkali tolerant crop varieties should be able to maintain normal physiological processes under high salt stress. This includes maintaining water balance, photosynthesis, and nutrient uptake. For instance, some crop varieties have developed mechanisms to maintain high water potential in their tissues, allowing them to continue absorbing water even in saline soils. Others have efficient antioxidant systems to scavenge reactive oxygen species produced under salt stress, thus protecting cellular components from oxidative damage.Thirdly, salt-alkali tolerant crop varieties should have good agronomic traits and high yield potential. It is important to select varieties that not only tolerate salt-alkali stress but also perform well in terms of growth, development, and yield. For example, some salt-alkali tolerant rice varieties have been developed with high yield potential and good grain quality, making them suitable for cultivation in saline-alkaline areas.In addition to these criteria, it is also important toconsider the specific requirements of different crops. Different crops have different strategies to cope withsalt-alkali stress, and the selection and breeding of salt-alkali tolerant varieties should take into account these crop-specific traits. For example, salt-alkali tolerant wheat varieties may have different mechanisms compared to salt-alkali tolerant soybean varieties.In conclusion, the selection and breeding of salt-alkali tolerant crop varieties require a thorough understanding of the physiological and genetic mechanisms underlying salt-alkali tolerance. By selecting and breeding varieties that meet the criteria of salt-alkali tolerance, we can contribute to the development of sustainable agriculture in salt-alkali affected regions.中文回答：耐盐碱作物品种的选育是确保粮食安全和可持续农业发展的关键。

收稿日期：2018-03-10第一作者简介：李委红（1993—），女，硕士研究生，研究方向为动物资源开发与功能食品。

E-mail：fallinlove7384@ *通信作者简介：刘会平（1964—），男，教授，博士，研究方向为动物资源开发与功能食品。

E-mail：liuhuiping111@不同乳化盐对再制干酪的影响及其复配优化李委红，刘会平*，田丽元，孙娜新，陈 沛，刘少娟，刘旭辉（天津科技大学食品工程与生物技术学院，食品营养与安全国家重点实验室，教育部食品营养与安全重点实验室，天津 300457）摘 要：以自制Mascarpone干酪和市售Cheddar干酪为原料制备再制干酪，研究4 种常见乳化盐（焦磷酸钠、六偏磷酸钠、多聚磷酸钠和柠檬酸钠）对再制干酪功能特性的影响，并进行乳化盐的复配优化。

结果表明：4 种乳化盐的乳化能力大小为焦磷酸钠＞柠檬酸钠＞多聚磷酸钠＞六偏磷酸钠；根据单因素试验结果，采用响应面法，选择焦磷酸钠、柠檬酸钠和多聚磷酸钠进行乳化盐复配优化，得出乳化盐的最佳配方为多聚磷酸钠添加量0.70%、柠檬酸钠1.50%、焦磷酸钠0.40%。

关键词：再制干酪；Mascarpone干酪；Cheddar干酪；乳化盐；响应面法；优化Effect of Different Emulsifying Salts on Processed Cheese and Optimization of Their CombinationLI Weihong, LIU Huiping*, TIAN Liyuan, SUN Naxin, CHEN Pei, LIU Shaojuan, LIU Xuhui(State Key Laboratory of Food Nutrition and Safety, Key Laboratory of Food Nutrition and Safety, Ministry of Education, College of Food Engineering and Biotechnology, Tianjin University of Science and Technology, Tianjin 300457, China)Abstract: The purpose of this work was to address the effect of four common emulsifying salts (risodium phosphate, sodium hexametaphosphate, sodium polyphosphate and sodium citrate) on functional properties of processed cheese made from a mixture of the Mascarpone cheese prepared in our laboratory and commercial Cheddar cheese. Also, the combination of emulsifying salts was optimized. The emulsifying capacity of four emulsifying salts followed the decreasing order: trisodium phosphate > sodium citrate > sodium polyphosphate > sodium hexametaphosphate. Trisodium phosphate, sodium citrate and sodium polyphosphate were selected for combination. The optimization was carried out using one-factor-at-a-time method and response surface methodology. The optimal combination obtained was sodium polyphosphate 0.70%, sodium citrate 1.50%, trisodium phosphate 0.40%.Keywords: processed cheese; Mascarpone cheese; Cheddar cheese; emulsifying salt; response surface methodology; optimization DOI:10.15922/ki.jdst.2018.03.004中图分类号：TS252.1 文献标志码：A 文章编号：1671-5187（2018）03-0019-06引文格式：李委红, 刘会平, 田丽元, 等. 不同乳化盐对再制干酪的影响及其复配优化[J]. 乳业科学与技术, 2018, 41(3): 19-24. DOI:10.15922/ki.jdst.2018.03.004. LI Weihong, LIU Huiping, TIAN Liyuan, et al. Effect of different emulsifying salts on processed cheese and optimization of their combination[J]. Journal of Dairy Science and Technology, 2018, 41(3): 19-24. DOI:10.15922/ki.jdst.2018.03.004. 再制干酪是以不同成熟期的同种或2 种以上天然奶酪为主要原料，添加乳化盐，在一定真空条件下不断加热、搅拌、乳化，直到形成一团具有所需结构特性、光滑、均匀的物质[1-2]；还可以向其中添加黄油（或无水乳脂肪、奶油）、脱脂乳、水和稳定剂（胶体），也可以添加香精、色素等。

山东化工收稿日期：2018－10－10作者简介：佘荆丽（1984—），女，2006年毕业于景德镇陶瓷学院，研究方向为硫酸钙的标准檿檿檿檿檿檿檿檿檿檿檿檿檿檿殨殨殨殨。

分析与测试不同水质对食品添加剂硫酸钙主含量检测结果的影响佘荆丽，张强，阮红玲（荆门市磊鑫石膏制品有限公司，湖北荆门448000）摘要：本实验采用《GB1886．6－2016食品安全国家标准食品添加剂硫酸钙》中主含量检测方法，比较了四种不同水质对食品添加剂硫酸钙主含量检测结果的影响。

实验结果表明：不同水质对最终结果的影响有很大差异，自制蒸馏水在实验过程中滴定显色出现异常，最终检测的主含量比使用国家标准规定用水检测的结果偏低，自来水和市售瓶装纯净水滴定显色正常，但最终结果偏大或偏小。

因此检验过程中不能使用其它三种水代替，会造成较大误差。

关键词：水质；食品添加剂硫酸钙；主含量；检测结果中图分类号：O655．2文献标识码：A文章编号：1008－021X （2019）04－0056－03Effect of Different Water on the Food Additive Calcium Sulfate Main ContentShe Jingli ，Zhang Qiang ，Ｒuan Hongling（Jingmen Leixin Gypsum Products Co．，Ltd．，Jingmen 448000，China ）Abstract ：This experiment adopted the main content detection method in GB1886．6－2016food safety food additive calciumsulfate ，and compared the influence of four different water quality on the main content detection result of food additive calcium sulfate．The experimental results show that the effect of different water quality on the final results is very different．The titration color of homemade distilled water is abnormal in the experimental process ，the main content of the final test was lower than that of the water tested according to the national standard．The titration of tap water and bottled water in the market showed normal color ，but the final result was relatively large or small．Therefore ，the other three types of water cannot be used in the inspection process ，which will cause a large error．Key words ：water quality ；food additive calcium sulfate ；main content ；test result硫酸钙作为食品添加剂在世界各地的食品加工过程中应用广泛。

碱性盐对小麦粉面筋特性和面条蛋白质组分的影响范会平1，2，陈月华2，符锋3，艾志录2，卞科1（1.河南工业大学粮油食品学院，河南郑州 450001）（2.河南农业大学食品科学技术学院，河南郑州 450002) （3.河南省粮油饲料产品质量监督检验中心，河南郑州 450099）摘要：为研究碱性盐（Na2CO3+K2CO3）对小麦粉和其面条品质变化的影响，以3种不同筋力的小麦品种为试验材料，结合SDS-PAGE电泳法，探讨了Na2CO3和K2CO3复配比例和碱性盐添加量对其小麦粉面筋特性和面条中蛋白质组分及分子量变化的影响，并结合SDS-PAGE电泳法考察了碱性盐对面条中蛋白质分子量分布变化的影响。

结果表明：添加碱性盐后，3种小麦粉的湿面筋和干面筋含量减少而面筋指数增加，其中西农979湿面筋含量由36.04%逐渐下降至26.58%，干面筋含量由12.22%下降至7.74%。

碱性盐使得3种小麦面条粉中的清蛋白和盐溶蛋白含量整体上显著增加而球蛋白和面筋蛋白含量整体上显著减少，GMP含量变化不显著但醇溶蛋白与谷蛋白含量减少，其中由矮抗58制得的面条中醇溶蛋白含量随着碱性盐添加量的增加由4.12%降至1.69%，而谷蛋白含量则由4.44%降至2.77%，研究结果可以为面条的工业化生产提供理论依据。

关键词：碱性盐；蛋白质；麦谷蛋白大聚体；盐溶蛋白；面筋蛋白文章篇号：1673-9078(2019)12-61-69 DOI: 10.13982/j.mfst.1673-9078.2019.12.009 Effects of Alkaline Salts on Gluten Characteristics of Wheat Flour andProtein Composition of Derived NoodlesFAN Hui-ping1,2, CHEN Yue-hua2, FU Feng3, AI Zhi-lu2, BIAN Ke1(1.College of Grain, Oil and Food Science, Henan University of Technology, Zhengzhou 450001, China)(2.College of Food Science and Technology, Henan Agricultural University, Zhengzhou 450002, China)(3.Henan Center for Supervision & Inspection of Grain, Oil and Feed Product Quality, Zhengzhou 450099, China)Abstract: In order to investigate the effects of alkaline salts (composed of sodium carbonate and potassium carbonate) on the quality of wheat flour and derived noodles, three wheat varieties with different gluten strengths were used as the experimental materials for the study on the impacts of different mass ratios of sodium carbonate to potassium carbonate and the amounts of alkaline salts for addition on the gluten characteristics of wheat flour, and the protein composition and molecular weight changes of derived noodles. The effects of alkaline salts on the molecular weight distribution of proteins in the noodles were investigated by SDS-PAGE electrophoresis. The results showed that the addition of alkaline salts could decrease the wet and dry gluten contents in the three varieties of wheat flours while increasing the gluten index. Among which the wet gluten of Xinong 979 declined from 36.04% to 26.58%, with its dry gluten content decreasing from 12.22% to 7.74%. Alkaline salts could increase the overall contents of albumin and salt-soluble proteins while decreasing significantly the contents of globulin and gluten proteins in the three kinds of noodles. The content of GMP did not change significantly, whilst the contents of gliadin and glutenin decreased upon the addition of alkaline salts. With the increase of added alkaline salt, the content of gliadin in the noodles made from Aikang 58 decreased from 4.12% to 1.69% with the content of glutelin also decreasing from 4.44% to 2.77%. The research results provide a theoretical basis for the industrial production of noodles.Key words: alkaline salts; protein; glutenin macropolymer; salt soluble protein; gluten protein面条因其具有制作工艺简单、食用方便及适合消费人群范围广等的特点，深受我国、日本、朝鲜等东收稿日期：2019-06-05基金项目：河南省博士后基金项目（2015093）作者简介：范会平（1972-），女，博士，副教授，研究方向：农产品加工与贮藏、功能活性成分开发与应用通讯作者：卞科（1960-），男，教授，研究方向：农产品贮藏与加工 亚国家人民的喜爱，在世界范围内约有40%的人口以面条为主食。

盐碱地改良方法题库Salt-alkaline land is a widespread issue that affects agricultural productivity and environmental sustainability in many regions around the world. 盐碱地是世界许多地区普遍存在的问题，影响着农业生产力和环境可持续性。

The high concentrations of salts and alkalis in the soil hinder plant growth and reduce crop yields, leading to economic losses for farmers. 土壤中高浓度的盐碱物质阻碍了植物的生长，降低了作物产量，给农民带来经济损失。

To improve salt-alkaline land, various methods and technologies have been developed and implemented. 为了改良盐碱地，人们开发和实施了各种方法和技术。

One commonly used method is soil leaching, which involves flushing the soil with water to remove excess saltsand alkalis. 其中一个常用的方法是土壤淋洗，即用水冲洗土壤以去除多余的盐碱物质。

This process helps to reduce soil salinity and improve its fertility for plant growth. 这个过程有助于降低土壤盐分，改善土壤肥力，促进植物生长。

Another effective approach to reclaiming salt-alkaline land is through the use of soil amendments such as organic matter, gypsum,and elemental sulfur. 另一个有效的盐碱地治理方法是利用有机物、石膏和硫等土壤改良剂。