Soil remediation of degraded coastal saline wetlands by irrigation with paper mill effluent and

Journal of Agricultural Catastrophology 2023, Vol.13 No.10我国设施农业土壤生态存在的问题及其解决措施刘 甜，蔡喜运*大连理工大学环境学院，辽宁大连 116024摘要 由于设施农业可以大幅度提高生产力水平，近年来我国的设施农业得到大规模发展。

设施农业快速发展的同时存在长期密集重茬种植和过量使用化肥农药等现象，加上设施农业需要高温高湿、缺乏雨水淋溶的环境条件，共同导致设施农业的土壤出现退化。

综述了目前设施农业土壤存在的土壤养分失调、土壤酸化、土壤次生盐渍化、土壤生物环境恶化和土壤污染6个方面的退化问题和成因，并简述了不同的设施土壤修复技术，为控制设施农业土壤生态环境退化提供思路。

关键词 设施农业；土壤质量退化；设施土壤修复中图分类号：S154 文献标识码：B 文章编号：2095–3305(2023)10–0302-03设施农业是指在受控的室内环境中种植农作物的一种农业系统。

与传统的露地农业相比，设施农业可以大幅度提高生产力和水的使用效率等，设施农业的单位面积生产力比传统农场高10~20倍。

近年来，我国设施农业规模发展迅速，总面积超过世界设施农业的80%。

在北京市的统计中，设施农业收入占农业总产值的比重在2019年已达到46%[1]。

然而，为了尽可能实现较大的经济效益，设施农业中常常出现土地密集使用、过度使用肥料和农药，使用质量不明的灌溉水等情况。

目前，设施农业中农户都是根据自己的经验进行管理，没有针对土壤的具体情况进行管理，导致设施农业土壤的退化和污染问题，如土壤养分失调、土壤酸化、土壤次生盐渍化和土壤农药污染等，严重影响了作物的品质和产量，制约了设施农业的发展。

1 设施农业土壤质量退化存在的问题1.1 土壤养分失调设施农业土壤退化的一个重要特征是有机物的逐渐损失，也是设施农业土壤生产力下降的主要因素。

测量国内有一定运行年限的设施农业土壤的有机质含量，发现其值为2.5%~4.0%，低于发达国家(8%~10%)。

小学下册英语能力测评(含答案)考试时间：80分钟（总分:120）A卷一、综合题(共计100题共100分)1. 听力题：A __________ is a major geological feature of the earth.2. 选择题：What do you call a person who studies the stars?A. AstronomerB. AstrophysicistC. CosmologistD. Meteorologist3. 听力题：I have a ______ of stickers. (book)4. 填空题：The flamingo stands on one leg to _________ (休息).5. 选择题：What do you call a person who studies chemistry?A. ChemistB. BiologistC. PhysicistD. Mathematician答案: A6. 选择题：What is the capital of Algeria?A. AlgiersB. OranC. ConstantineD. Annaba答案:A. Algiers7. 选择题：Which vegetable is orange and long?A. TomatoB. CarrotC. PotatoD. Onion答案:B8. 听力题：The _____ (kite/balloon) is flying high.9. 听力题：The chemical reaction of burning is called _____.10. 填空题：He is very _____ (善于沟通) in meetings.11. 选择题：What do you wear on your feet?A. HandsB. ShoesC. HeadD. Eyes答案:B12. 选择题：What is the main gas that plants use for photosynthesis?A. OxygenB. Carbon dioxideC. NitrogenD. Helium答案:B. Carbon dioxide13. 填空题：A tapir has a short ______ (鼻子).14. 填空题：Many plants have adapted to be ______ (抗旱).15. 选择题：What do you call a baby pig?A. PigletB. CalfC. KidD. Foal答案: A16. 填空题：A _____ (气候适应) helps plants survive in extreme weather.17. 选择题：What do you call a large group of fish?A. SchoolB. SwarmC. PodD. Flock18. 填空题：Birds can _________ in the sky. (飞)19. 选择题：What do you call a person who writes plays?A. AuthorB. PlaywrightC. DirectorD. Producer20. 填空题：Lions live in _______ (群体).21. 选择题：What is the capital of India?A. New DelhiB. MumbaiC. KolkataD. Chennai答案: A22. 选择题：What is the name of the famous Egyptian queen known for her beauty?A. NefertitiB. CleopatraC. HatshepsutD. Tutankhamun答案: B. Cleopatra23. 填空题：My ________ (玩具) is a source of laughter.My ________ (祖父) loves to tell stories about his adventures.25. 填空题：A goldfish swims in the ______ (水) of its bowl.26. 选择题：What do you call the study of the Earth's physical features?A. BiologyB. GeographyC. GeologyD. Astronomy答案:B27. 听力题：The ____ has a distinctive tail that helps it balance.28. ecosystem service) benefits humans and nature. 填空题：The ____29. 听力题：The chemical formula for potassium carbonate is ______.30. 填空题：The _____ (蜜蜂) buzzes around the flowers collecting nectar. 蜜蜂在花丛中嗡嗡作响，采集花蜜。

Littering is a serious environmental issue that affects our planet in numerous ways. When people carelessly dispose of their waste,it leads to pollution that can harm the Earths ecosystems and the health of its inhabitants.1.Impact on Wildlife:Animals often mistake litter for food,leading to ingestion of harmful materials such as plastic bags,which can cause internal injuries or blockages.Birds,for example,may feed plastic to their chicks,resulting in malnutrition or death.Additionally,animals can become entangled in discarded fishing lines or nets,leading to injury or even death.2.Water Contamination:When litter,particularly plastic,enters water bodies such as rivers,lakes,and oceans,it can cause significant harm.It can break down into microplastics,which are tiny particles that can be ingested by aquatic organisms.These microplastics can then enter the food chain,potentially affecting human health when consumed.3.Soil Degradation:Litter can also affect the quality of soil.For instance,decomposing waste can release chemicals that alter the soils pH levels,making it less fertile and harmful to plant life. Moreover,certain types of waste,like Styrofoam,do not decompose naturally and can remain in the soil for hundreds of years.4.Air Pollution:Open burning of waste,a common practice in some areas,releases toxic fumes into the air.These fumes contain harmful substances like dioxins and particulate matter,which can contribute to respiratory problems and other health issues.5.Aesthetic Degradation:Litter also detracts from the natural beauty of our environment.It can make public spaces, parks,and beaches appear dirty and neglected,which can discourage people from enjoying these areas and reduce the overall quality of life.6.Economic Impact:The cost of cleaning up litter can be significant,placing a burden on taxpayers and local governments.Moreover,littered areas can deter tourism and investment,affecting local economies.7.Climate Change:Some types of litter,particularly plastic,can contribute to climate change.The production and disposal of plastic generate greenhouse gases,and the breakdown of plastic in theenvironment releases methane,a potent greenhouse gas.To combat littering and its associated pollution,it is essential to adopt sustainable waste management practices.This includes reducing the use of singleuse plastics,recycling, and properly disposing of cation and awareness campaigns can also play a crucial role in changing public behavior and encouraging people to take responsibility for their waste.In conclusion,littering is not just an eyesore it is a threat to our environment and the wellbeing of all living creatures.By taking action to reduce litter,we can help preserve the Earth for future generations.。

土壤污染发言稿英语Ladies and gentlemen, esteemed guests, and fellow advocates for environmental preservation, it is with great concern that I address the pressing issue of soil contamination and pollution today. Soil, the very foundation of life on Earth, is under threat from numerous sources of pollution that have detrimental effects on the environment, public health, and the sustainability of agriculture. As individuals, communities, and nations, it is our collective responsibility to address and mitigate the impacts of soil pollution in order to safeguard the health and well-being of current and future generations.First and foremost, it is crucial to understand the sources and causes of soil pollution. Soil contamination can arise from a variety of human activities, including industrial and agricultural practices, improper waste disposal, mining, and the use of harmful chemicals and pesticides. Pollutants such as heavy metals, petroleum products, pesticides, and toxic chemicals can leach into the soil, rendering it unfit for agricultural purposes and posing serious risks to human health and ecosystems. In addition, soil erosion and deforestation exacerbate the problem by accelerating the spread of pollutants and reducing the capacity of the soil to support life.The consequences of soil pollution are far-reaching and impactful. Contaminated soil can lead to the loss of biodiversity, the degradation of ecosystems, and the disruption of natural processes. In agricultural areas, soil pollution can compromise food safety and security, as crops grown in contaminated soil may accumulate harmful substances that pose health risks to consumers.Furthermore, the exposure to contaminated soil can have adverse health effects on humans and animals, including respiratory problems, organ damage, and cancer. The long-term implications of soil pollution also extend to economic and social hardships, as affected communities grapple with the costs of remediation, loss of agricultural productivity, and compromised living conditions.It is evident that urgent action is needed to address soil pollution and its associated challenges. By adopting a multi-faceted and holistic approach, we can work towards effective solutions to mitigate and prevent soil contamination. Firstly, we must prioritize the implementation of sustainable land management practices, such as agroecology and organic farming, which promote soil health and fertility while minimizing the use of harmful chemicals. Additionally, we must invest in the remediation of contaminated sites and the restoration of degraded soils through the application of innovative technologies and best practices. This can involve the use of phytoremediation, biochar, and other ecologically sustainable methods to rehabilitate polluted soil and mitigate the spread of contaminants.Furthermore, it is imperative to strengthen regulations and enforcement measures to prevent soil pollution at its source. By holding industries and agribusinesses accountable for their environmental impact and promoting the adoption of cleaner production methods, we can reduce the discharge of pollutants into the soil and safeguard the integrity of our natural resources. In addition, we must promote responsible waste management practices, including the proper disposal and treatment of hazardous waste, to prevent the accumulation of toxic substances in the soil.Education and awareness-raising also play a vital role in addressing soil pollution. By fostering a greater understanding of the environmental, social, and economic implications of soil contamination, we can mobilize individuals, communities, and policymakers to take action for the protection of our soils. Empowering local communities with knowledge and resources to monitor and address soil pollution can lead to grassroots initiatives that contribute to a more sustainable and resilient environment.International cooperation and collaboration are essential components in the fight against soil pollution. As a global issue that transcends borders, soil contamination demands a collective effort to develop and implement effective strategies for pollution prevention, restoration, and sustainable land management. By exchanging knowledge, sharing best practices, and fostering partnerships, we can work towards a future where soil pollution is minimized, and the health and productivity of our soils are preserved for generations to come.In conclusion, the threat of soil pollution is a significant and urgent challenge that requires our immediate attention and action. By acknowledging the scope of the problem and committing to sustainable and responsible practices, we can protect and restore the health of our soils, safeguard the well-being of communities and ecosystems, and secure a sustainable future for all. I urge all of us to join hands in the collective effort to address soil pollution and ensure a healthy and resilient environment for generations to come. Thank you.。

Pollution Prevention and Environmental Protection Measures IntroductionPollution is a major threat to the environment and human health. It is caused by various factors, such as excessive use of natural resources, industrial activities, transportation, and improper disposal of waste. Pollution can have adverse effects on air, water, soil, and biodiversity. Therefore, it is essential to adopt effective measures to prevent pollution and promote environmental protection. In this article, we will discuss some of the most important pollution prevention and environmental protection measures.Pollution Prevention MeasuresUse of Clean TechnologiesClean technologies are innovations that aim to reduce the negative environmental impact of human activities. They include renewable energy sources, energy-efficient equipment, waste reduction strategies, and sustainable production methods. By adopting clean technologies, we can minimize pollution and conserve natural resources. For example, using solar and wind power for energy production can reduce carbon emissions, whereas optimizing manufacturing processes can reduce waste and resource consumption.Waste ManagementWaste management involves the proper handling, storage, transportation, and disposal of waste materials. It is a critical aspect of pollution prevention because improper waste management can lead to soil contamination, air pollution, and water pollution. To address this issue, we need to implement waste reduction, reuse, and recycling strategies. By reducing the amount of waste generated and diverting it from landfills, we can minimize the environmental impact of waste.Environmental RegulationsEnvironmental regulations are laws and policies that govern the use of natural resources and the discharge of pollutants. These regulations are designed to protect the environment and public health by setting standards for pollution prevention and remediation. Some examples of environmental regulations include emissions standards for vehicles, water quality standards for drinking water, and hazardous waste disposal regulations.Environmental Protection MeasuresConservation of Natural ResourcesConservation of natural resources involves the sustainable use and management of natural resources, such as water, forests, and wildlife. It is essential for maintaining ecological balance and biodiversity. To conserve natural resources, we need to adopt sustainable practices, such as reducing water consumption, protecting forests and wildlife habitats, and promoting eco-tourism.Restoration of Degraded EcosystemsMany ecosystems have been degraded due to pollution, deforestation, and other human activities. To restore these ecosystems, we need to implement restoration projects, such as reforestation, wetland restoration, and habitat restoration. These projects can help to improve ecological functioning, enhance biodiversity, and mitigate the negative impact of pollution.Environmental Education and OutreachEnvironmental education and outreach are essential for promoting environmental awareness and behavior change. They involve educating people about the causes and consequences of environmental problems, as well as the actions they can take to address them. Environmental education can take many forms, such as school programs, public awareness campaigns, and community outreach programs.ConclusionPollution prevention and environmental protection measures are critical for ensuring a healthy and sustainable future for all. By adopting clean technologies, implementing waste management strategies, enforcing environmental regulations, conserving natural resources, restoring degraded ecosystems, and promoting environmental education and outreach, we can minimize pollution and promote environmental sustainability. It is up to all of us to take action and contribute to a better world.。

退化林修复技术规程（试行）1范围本文件规定了退化林修复总则、技术流程、退化林判别、退化等级划分、修复措施选择、作业设计文件编制、修复作业施工、质量评价与档案管理等方面的内容。

本文件适用于退化用材林和防护林修复，其他林种可参照执行。

2规范性引用文件下列文件中的内容通过文中的规范性引用而构成本文件必不可少的条款。

其中，注日期的引用文件，仅该日期对应的版本适用于本文件；不注日期的引用文件，其最新版本（包括所有的修改单）适用于本文件。

GB/T15163封山（沙）育林技术规程GB/T15776造林技术规程GB/T15781森林抚育规程GB/T26424森林资源规划设计调查技术规程LY/T1646森林采伐作业规程3术语和定义下列术语和定义适用于本文件。

3.1退化林degraded forest受到人为干扰或自然灾害影响，森林结构发生逆向改变，森林生态系统服务功能或生产力持续性明显下降，依靠自然力短期内难以恢复的森林。

3.2退化林修复remediation and restoration of degraded forest通过采取科学的人工措施，改善退化林森林结构，提高森林质量，恢复森林功能，促进森林正向演替的活动或过程。

3.3目标林相target forest根据地带性顶极森林群落或按照特定培育目的，确定的培育目标林分的特征。

注：通常用树种组成、群落结构和蓄积量等指标来描述。

3.4全周期修复设计full cycle remediation and restoration design按照森林发育阶段，从退化林现状到目标林相的全过程，做出系统性的培育措施设计。

3.5竞争生长阶段competitive growth stage森林郁闭后林木互利竞争，出现快速高生长的发育阶段。

3.6质量选择阶段quality selection stage林木间出现明显的互斥竞争并显著分化，相邻竞争林木表现为明显的优势木和被压木特征，林下开始出现天然更新幼苗幼树的发育阶段。

国外盐碱地治理案例1. The Alkali Ridge Project, Utah, USA: This project involved the conversion of 120,000 acres of barren land into productive farmland in the 1950s. The project involved a combination of soil reclamation methods such as deep plowing, addition of soil amendments like calcium, magnesium and gypsum, and the installation of subsurface tile drainage systems.2. The Saline Agriculture for Marginal Lands (SALTMED) project, Tunisia: This project aimed to transform over 1000 hectares of unproductive saline land into arable farmland using innovative irrigation techniques, desalination methods, crop selection and genetic modifications to enhance plant tolerance to saline soils.3. The Mazarrón Saltmarsh Wetlands, Spain: This project involved the restoration of 100 hectares of degraded saltmarsh wetlands through the creation of artificial tidal channels, installation of tide gates, and the planting of salt-adapted vegetation to help prevent coastal erosion and reduce salinization.4. The Dongting Lake Wetlands, China: This project aimed to revive the ecological function of the Dongting Lake ecosystem by restoring degraded wetlands and removing invasive plant species. The project involved the creation of artificial wetlands toreduce the pollutant load entering the lake and the reestablishment of native vegetation.5. The Hillel Irrigation Canal, Israel: This project involved the construction of a 30-kilometer-long irrigation canal in the Negev Desert to bring water from the Red Sea to irrigate croplands. The project also included experiments with salt-tolerant crops and innovative irrigation and soil management techniques to improve soil fertility and reduce salinity levels.These are just a few examples of successful salt-affected soil remediation projects from around the world, each tailored to the specific natural and socio-economic conditions of the region.。

Soil organic carbon as functions of slope aspects and soil depths in a semiarid alpine region of Northwest ChinaMeng Zhu a ,b ,Qi Feng a ,⁎,Yanyan Qin a ,b ,c ,Jianjun Cao d ,Huiya Li a ,b ,Yu Zhao a ,baKey Laboratory of Ecohydrology of Inland River Basin,Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China bUniversity of Chinese Academy of Sciences,Beijing 100049,China cResearch Institute of Forestry Science of Bai Long Jiang Forestry Management Bureau,Lanzhou 730070,China dCollege of Geography and Environment Science,Northwest Normal University,Lanzhou 730070,Chinaa b s t r a c ta r t i c l e i n f o Article history:Received 1March 2016Received in revised form 5January 2017Accepted 10January 2017Available online 14January 2017Soils in alpine regions associated with complex topography are characterized by large variability in the spatial distribution of soil organic carbon (SOC).However,the patterns and topographic controls on SOC at the hill scale in semiarid alpine regions are not well understood.In this study,the effects of slope aspects and depths on SOC were quanti fied based on field investigations in a mainly undisturbed region of the Qilian Mountains in northwestern China.Soil samples were collected at 0–10,10–20,20–40and 40–60cm on south-,southwest-,west-,and north-facing slopes of three hills.Results showed that the SOC density at 0–60cm varied from 9.73to 35.21kg m −2,and increased from the south-to north-facing slopes.The average SOC density on the north-fac-ing slopes was about 3.2,2.9and 1.9times larger than on the south-,southwest-and west-facing slopes.Both the general linear model and mixed linear model suggested that,at the hill scale,the slope aspects and soil depths explained the main variations of SOC concentration in our study.The pro file pedotransfer function method indi-cated that the SOC varied predictably with soil depths and aspects,and the prediction functions well predicted the SOC data from literature.Our results highlight the importance of slope aspect as an indicator of the SOC,and demonstrate that the transformed aspect is a good continuous variable in predicting the SOC in the semiarid alpine region.©2017Elsevier B.V.All rights reserved.Keywords:Semiarid alpine region Soil organic carbon Slope aspect Soil depthPro file pedotransfer function1.IntroductionThe effect of complex topography on soil organic carbon (SOC)con-tributes large uncertainties to the accurate estimation of SOC storage in alpine regions (Arrouays et al.,1998;Gessler et al.,2000;Chaplot et al.,2001;Yimer et al.,2006;Li et al.,2007;Hancock et al.,2010;Lenka et al.,2013;Huang et al.,2015;Chen et al.,2016).Slope aspect,an important topographic variable,substantially modi fies both the solar radiation in-tensity and the ecological processes on hillslopes,and create microcli-mates that differ signi ficantly from the regional climatic conditions (Buffo et al.,1972;Flint and Childs,1987;Nikolov and Zeller,1992;McCune and Keon,2002;Bennie et al.,2008;Zhang et al.,2015).Vege-tation communities and species occurrence are also modi fied by these microclimatic conditions at different slope aspects (Holland and Steyn,1975;Rorison et al.,1986;Sternberg and Shoshany,2001;Amezaga and Onaindia,2009;Bennie et al.,2006;Aström et al.,2007).The chang-ing climatic,hydrological and ecological conditions result in high vari-ability in SOC at smaller scales in the alpine region.Slope aspect plays an important role in redistributing the solar radi-ation.According to the equations presented by McCune and Keon (2002),potential annual direct incident radiation is the maximum on the south-facing slopes and the minimum on the north-facing slopes over the mid-latitudes in the Northern Hemisphere.The heterogeneity of solar radiation on hillslopes results in the differences in temperature and soil water content.Rorison et al.(1986)found that there was a 2.5–3°C annual mean temperature difference on adjacent slopes in a British calcareous landscape.The accumulation of SOC varies on hillslopes be-cause of the differences in litter input and the decomposition rates of or-ganic matter (Post et al.,1982;Alvarez and Lavado,1998;Yimer et al.,2006).Huang et al.(2015)found that the SOC concentration on half-shaded and shaded aspects was signi ficantly higher than the sunny as-pects in the Chinese loess region.Similar results were also found by Lenka et al.(2013)in a degraded al fisol in the Indian subtropics,where SOC concentration was 11–12%higher on the north-facing aspect than the east-facing aspect.In another two studies performed near the equatorial region,the SOC concentration was higher on the southern as-pects and the lower northern aspects because of higher precipitation and lower temperature on the southern aspect (Yimer et al.,2006;Sigua and Coleman,2010).Slope aspects also affect the distribution of SOC by altering the precipitation at a larger scale.Pu et al.(2008)Catena 152(2017)94–102⁎Corresponding author.E-mail address:qifeng@ (Q.Feng)./10.1016/j.catena.2017.01.0110341-8162/©2017Elsevier B.V.All rightsreserved.Contents lists available at ScienceDirectCatenaj ou r n a l h o m e pa ge :ww w.e l s e v i e r.c o m /l oc a t e /c a t e n afound that the SOC concentration was higher on the windward (east)compared to the leeward (west)slopes in the northern Hengduan Mountains region in southwest China,attributing this distribution pat-tern to the higher precipitation (1735mm)on the windward slopes and lower on the leeward slopes (640mm).Soil depth is an important variable in modeling the vertical distribu-tion pattern of SOC and investigating organic carbon storage at a region-al scale.The vertical distribution pattern of SOC enables us to estimate the organic carbon storage in the subsoil from the topsoil data,and to quantify and map the SOC for different soil depths (Mestdagh et al.,2004;Yang et al.,2007).Generally,the relations between SOC and depths can be expressed by many mathematical functions (exponential,logarithmic,power and quadratic).Among these functions,the expo-nential function was most widely employed (Minasny et al.,2006).In semiarid alpine regions,soil water availability is a main environ-mental control involved in shaping the ecosystem productivity because of the relatively low annual precipitation and strong potential transpira-tion.Topography,which exerts a signi ficant in fluence on the spatial var-iability of soil water content (Li et al.,2015;Gao et al.,2015),may signi ficantly affect the accumulation of organic carbon in semiarid al-pine soils.However,the distribution pattern of SOC at the hillslope scale in semiarid alpine region is less understood,especially in high al-titude regions.This is mainly because of their limited accessibility.Moreover,although the effect of slope aspects on SOC is widely recog-nized,few studies have been conducted to examine the quantitative re-lation of SOC with slope aspects and soil depths (Lenka et al.,2013;Huang et al.,2015;Chen et al.,2016).Therefore,the main goals of this study are (1)to investigate the distribution patterns of SOC along the as-pect and depth gradients,(2)to determine the contributions of slope as-pects and depths to the overall variation of SOC at the hill scale,and (3)to construct the SOC prediction functions with slope aspects and soil depths as independent variables.2.Materials and methods 2.1.Study areaThe study was carried out in the Xishui Forest Zone (100°03′–100°23′E,38°23′–38°48′N)of the Qilian Mountains National Forest Re-serve,which lies in the north edge of Qinghai –Tibet Plateau,Northwest-ern China.The Xishui Forest Zone covers an area of 7239.8km 2with elevation ranging from 2400to 4000m,and is characterized by a semi-arid climate with an annual average temperature of 0.7°C and annual average precipitation of 435mm (Chang et al.,2013).The landscape in the study area is forest-steppe,which represents the main landscape type in the middle Qilian Mountains (Lu et al.,2001).Vegetationpatterns are closely related to the slope aspect,and represent a mosaic of grasslands and forests (Chen et al.,2016).At our sampling sites,grass-lands occupy mainly south-,southwest-,and west-facing slopes with the dominant species including Agropyron cristatum ,Carex crebra ,Stipa capillata Linn,and Kobresia humilis .Forests,dominated by Qinghai spruce (Picea crassifolia ),are mainly distributed on northwest-and north-facing slopes (Table 1).The soils,according to the taxonomic clas-si fication system,are mainly argic-ustic semi-luvisols on north-facing slopes and calcaric-ustic pedocal on other aspects.In the Picea crassifolia forest,there was a clear gravel composition,mainly of calcareous rock,below 60cm.2.2.Experimental designIn this study,we selected three sites in total (Hills A,B,and C)as the replicates with similar landscape type (forest-steppe),elevation (about 2950m),and slope (33°)in the middle Qilian Mountains (Fig.1,Table 1).The relative elevations of the three hills were b 100m,which enabled us to control the effect of elevations on the SOC and to focus on the var-iation of SOC along the aspect gradients.On each hill,we examined tran-sects from the south-(SFS,azimuth angle of 180°),southwest-(SWFS,225°),west-(WFS,270°)to north-facing slope (NFS,360°).Along each transect,three sampling positions (1to 3)were selected from the shoulderslope to footslope position (Fig.1c).Each sampling position contained three plots,and the size of each plot was (5×5)m 2on SFS,SWFS,and WFS (mainly occupied by grasslands),and 10×10m 2on NFS (forests).Within each plot,three soil pro files were excavated (after removing the surface litter layer),and soil samples of 5.00cm in diameter and 5.05cm in length were collected by the core ring method (100cm 3core volume)at 5,15,30,and 50cm,and were oven dried at 105°C for 24h to obtain the dry weight for calculating the bulk density (Blake and Hartge,1986).Soil samples for chemical analyses were col-lected next to each soil pro file using a soil auger (3.5cm in diameter)at 0–10,10–20,20–40,and 40–60cm.Soil samples (three replicates)from each plot were pooled to give a composite sample from each of the four depth intervals.In total,324soil pro files were excavated and 432composite soil samples were collected for SOC concentration anal-ysis in this study.2.3.Soil analysesIn the laboratory,soil samples were air-dried and passed through a 2mm sieve to remove the gravel and roots.SOC concentration was de-termined by wet oxidation with dichromate according to the Walkley –Black method (Nelson and Sommers,1982).Table 1Geographical and vegetative characteristics of the sampled transects on the three hills.HillTransectLength (m)Slope (°)Elevation of sampling position (m)Vegetation typesCover (%)Dominant species123ASFS 5030291229052897grassland 30Agropyron cristatum,Kobresia capillifolia SWFS 7233290328902874grassland 45Agropyron cristatum,Carex crebra WFS 12537290228812849grassland 65Kobresia humilis,Carex crebra NFS 9331290128852864forest 70Picea crassifoliaBSFS 9128301229832964grassland 40Agropyron cristatum,Potentilla bifurca L.SWFS 13834300729792950grassland 60Carex crebra,Potentilla bifurca L.WFS 15736299629502938grassland 70Kobresia humilis,Potentilla bifurca L.NFS 7833300729902974forest 75Picea crassifoliaCSFS 11830296229402928grassland 35Agropyron cristatum,Stipa przewalskyi Roshev.SWFS 16133295829222886grassland 50Carex crebra,Agropyron cristatum WFS 17935295028992866grassland 60Kobresia humilis,Poa annua L.NFS7733296429482939forest75Picea crassifoliaNote:SFS,SWFS,WFS,and NFS are south-,southwest-,west-,and north-facing slopes,respectively.95M.Zhu et al./Catena 152(2017)94–1022.4.Data analysesThe SOC density of each soil pro file was calculated using Eq.(1)as follows:SOCD ¼∑nk ¼1C k D k B k 1−G k ðÞ=100ð1Þwhere SOCD is the SOC density (kg m −2),n is the number of layers di-vided in each soil pro file,and C k ,D k ,B k ,and G k represent the SOC con-centration (g kg −1),the thickness (cm),the bulk density (g cm −3),and the fractional percentage (%)of gravel larger than 2mm in diameter of layer k ,respectively.2.5.Statistical analysesTo investigate the contribution of slope aspects,soil depths and ele-vations to the overall variation of SOC on the three hills,we employed both general linear model (GLM)and mixed linear model (MLM).As the GLM is a linear statistical model,we transformed the aspects and depths with the cosine and logarithmic functions,respectively,and used the transformed aspects and depths as well as the untransformed elevations as the independent variable.In the MLM analysis,we select-ed the aspects,depths,and elevations as fixed-effects parameters,and the hill as a random-effects parameter.The GLM and MLM analyses were performed employing the GLM and MIXED procedures,respec-tively,in SAS 9.2(SAS Institute,Inc.,Cary,NC,USA).2.6.The pro file pedotransfer functionThe pro file pedotransfer function was applied to obtain the empiri-cal equations for predicting the SOC concentration and the density on each hill (Zinn et al.,2005).To describe the vertical distribution of SOC concentration at each as-pect,we applied Eq.(2)as follows:SOC concentration ¼a −b ln h ð2Þwhere h is soil depth (cm),and is included in calculations as the mid-point of sampling layer (e.g.5cm for 0–10cm),and a and b are coef fi-cients estimated by nonlinear regression.The variation of coef ficients a ,and b in Eq.(2)by slope aspect was described by Eq.(3)as follows:a ¼c 1e d 1cos A ðÞb ¼c 2e d 2cos A ðÞð3Þwhere a and b are the coef ficients in Eq.(2),A is azimuth angle of slope aspect (°),and c 1,d 1,c 2,and d 2are coef ficients estimated by nonlinear regression.We substituted Eq.(3)for coef ficients a and b in Eq.(2),and the SOC concentration at different aspects and depths was described by Eq.(4)as follows:SOC concentration ¼c 1e d 1cos A ðÞ−c 2e d 2cos A ðÞln hð4ÞTo quantify the effects of depths on SOC density,we applied the con-tinuous SOC density method (Yang et al.,2007).This method is based on continuous decreases in the SOC density with depth,and differs from the method in Eq.(1),which obtains the SOC density through summing up the densities of all soil layers divided in a soil pro file.The continuous SOC density method enabled us to estimate the SOC density at any given depth (Yang et al.,2007).Therefore,SOC density at depth h can be cal-culated as follows:SOCD h ¼C h B h 1−G k ðÞ=100ð5Þwhere SOCD h (kg m −2cm −1)is SOC density at depth h (cm),and C h ,B h ,and G h are the SOC concentration (g kg −1),the bulk density (g cm −3),and the fractional percentage (%)of gravel larger than 2mm in diameter at depth h ,respectively.Based on the pro file pedotransfer function,we first regressed the re-lation between SOCD h and azimuth angle of aspects,as follows:SOCD h ¼ae b cos A ðÞð6Þwhere a and b are coef ficients estimated by nonlinear regression.The variation of coef ficients a and b in Eq.(6)by depth was de-scribed by Eq.(7)as follows:a ¼c 1þd 1e e 1h b ¼c 2þd 2e e 2hð7Þwhere a and b are coef ficients in Eq.(6),and c 1,d 1,e 1,c 2,d 2,and e 2are coef ficients estimated by nonlinearregression.Fig.1.Location of study area and distribution of sampling plots on hillslopes.(a)Tridimensional surface map of study area,(b)images of Hills A,B and C,(c)3m contour map of Hill A indicating the distribution of soil pro files.The sampling method on Hills B and C is the same as Hill A.The SFS,SWFS,WFS,and NFS represent south-,southwest-,west-,and north-facing slope,respectively.96M.Zhu et al./Catena 152(2017)94–102Thus,the SOC density at0–h was obtained by calculating SOCD h for 0–h,as follows:SOCD¼∫hc1þd1e e1he c2þd2e e2hðÞcos AðÞdhð8Þ3.Results3.1.Distribution patterns of SOCThe SOC concentration in our sampling positions varied from24.10 to112.94,18.61to81.99,12.73to65.01,and8.59to53.08g kg−1at 0–10,10–20,20–40,and40–60cm,respectively(Table1).The SOC den-sity at0–60cm varied from9.73to35.21kg m−2.For grasslands on the SFS,SWFS and WFS,and forests on the NFS,the average SOC density at 0–60cm were13.33and33.64kg m−2,respectively.The results also showed that the SOC concentration increased from the SFS to NFS at each soil depths(Table2).The average topsoil(0–10cm)organic carbon concentration on the NFS(108.44±19.89g kg−1)was larger than on the SFS(25.10±5.70g kg−1), SWFS(28.92±4.75g kg−1),and WFS(54.09±14.01g kg−1)by factors of4.3,3.8,and2.0,respectively,and similar factors between aspects were also obtained at10–20,20–40,and40–60cm.The SOC concentra-tion showed a significantly decreasing trend with soil depth at all sam-pling positions,and the SOC concentration at0–10cm was about2to3 times larger than that at40–60cm.Along the transect from higher to lower elevations,the SOC concentration tended to be larger at the lower positions(except on the NFS),and the largest difference of SOC between elevations within the transect occurred on the WFS,where the topsoil organic carbon at2884m was about1.24times larger than that at2949m.The SOC density at0–60cm showed a similar distribution pattern compared with the SOC concentration along the aspect gradients (Table2).The amount of organic carbon stored in the soil on the NFS (33.64±5.82kg m−2)was about3.2,2.9and1.9times larger than on the SFS(10.52±2.13kg m−2),SWFS(11.74±1.65kg m−2)and WFS(17.72±3.43kg m−2).In addition,the organic carbon stored at 0–20cm was much higher than at20–40and40–60cm at all sampling positions.Table2Distribution patterns of SOC(mean±S.D.)Transect Elevation(m)Depth(cm)Bulk density(g cm−3)SOC concentration(g kg−1)SOC density(kg m−2)SOC density in0–60cmSFS2962±500–10 1.04±0.0924.10±3.69 2.49±0.379.93±1.5410–20 1.03±0.0420.28±4.31 2.07±0.3920–40 1.09±0.0514.96±2.48 3.26±0.5440–60 1.13±0.089.38±2.32 2.11±0.592943±390–10 1.12±0.0824.49±4.92 2.75±0.599.73±1.8410–20 1.14±0.1318.61±4.01 2.13±0.5520–40 1.13±0.1612.73±3.19 2.90±0.9840–60 1.18±0.188.59±2.45 1.96±0.402930±340–10 1.15±0.1126.45±8.00 2.97±0.6911.92±2.4010–20 1.09±0.1321.64±4.96 2.29±0.3320–40 1.09±0.1517.86±5.85 3.76±0.7840–60 1.10±0.1513.63±5.72 2.89±0.91SWFS2956±520–10 1.02±0.0431.12±3.78 3.17±0.3511.16±1.0510–20 1.01±0.0622.93±4.99 2.27±0.4320–40 1.05±0.1416.11±3.49 3.30±0.5140–60 1.10±0.2211.39±2.11 2.41±0.302930±450–10 1.09±0.0625.56±2.72 2.77±0.3011.06±0.9910–20 1.06±0.0620.22±1.65 2.14±0.2220–40 1.03±0.0816.80±2.30 3.48±0.6540–60 1.07±0.1112.53±1.46 2.66±0.272903±410–10 1.10±0.0430.31±5.57 3.33±0.5012.94±2.0210–20 1.06±0.0424.12±4.76 2.56±0.4720–40 1.04±0.0419.56±3.67 4.06±0.7740–60 1.04±0.0514.37±3.32 2.98±0.71WFS2949±470–100.91±0.1249.64±8.79 4.48±0.9416.88±2.6610–200.92±0.0933.61±7.62 3.06±0.4620–400.93±0.0528.78±7.51 5.32±1.1640–600.94±0.0621.48±6.27 4.03±1.102910±360–100.92±0.0951.09±12.51 4.61±0.9616.77±2.9410–200.97±0.0934.71±6.47 3.32±0.4720–400.95±0.0827.65±6.60 5.14±0.9340–600.95±0.0920.03±6.75 3.70±1.132884±470–100.87±0.1161.53±17.60 5.15±1.1819.52±4.1410–200.93±0.0843.34±11.55 3.92±0.8920–400.91±0.0631.98±8.41 5.73±1.5340–600.95±0.1525.20±8.49 4.71±1.71NFS2957±530–100.61±0.10106.07±12.34 6.36±1.1730.87±4.9210–200.65±0.1081.89±9.41 5.29±0.7020–400.80±0.2169.24±16.7910.65±2.1540–600.91±0.2149.17±19.648.57±3.352941±530–100.70±0.09112.94±20.947.78±1.5635.21±6.9810–200.86±0.1581.48±18.90 6.84±1.2220–400.88±0.1566.77±17.1211.45±2.6340–600.96±0.1347.17±11.089.15±2.872926±560–100.66±0.13106.32±25.727.06±1.9533.23±5.1610–200.78±0.1175.36±6.50 5.88±0.7420–400.82±0.1465.01±18.4110.21±2.4540–600.99±0.2153.08±18.8010.07±3.8997M.Zhu et al./Catena152(2017)94–1023.2.Effects of slope aspects and soil depths on SOCThe results of the GLM suggest that,at the hill scale,slope aspects,depths and elevations explained 80.19%,18.94%and 0.81%of the overall variation of SOC concentration (Table 3).In the MLM analysis,the over-all variation of SOC explained by slope aspects and depths was a bit higher than in the GLM analysis (Table 3).Although the effect of eleva-tions on SOC concentration was statistically signi ficant (P b 0.01),the variation explained by elevations was b 1%and 4%of that explained by aspects and depths,respectively.This demonstrated that,at the hillscale,the SOC distribution pattern can be well described with only as-pect and depth as the effect of elevations was tiny.3.3.SOC as functions of slope aspects and soil depthsAs the effect of elevation on SOC at the hill scale is trivial compared to the aspect and depth,we only used aspects and depths as indepen-dent variables in the construction of the pro file pedotransfer functions.Table 4Regression coef ficients of the SOC concentration vs.depth relations.HillTransectAspect (°)Cosine of aspectSOCconcentration =a −b ln(h )Coef ficient aCoef ficient b ASFS 180−1.00037.16 6.71SWFS 225−0.70736.63 6.13WFS 2700.00068.7710.66NFS 360 1.000152.6728.21BSFS 180−1.00039.55 6.53SWFS 225−0.70740.37 6.94WFS 2700.00094.4418.98NFS 360 1.000160.5527.25CSFS 180−1.00030.16 5.27SWFS 225−0.70744.747.65WFS 2700.00063.4911.45NFS3601.000130.9518.67Fig.2.Description of SOC concentration with azimuth angle of slope aspect and soil depth.(a1),(b1),and (c1)are regressions between SOC concentration and soil depth for Hills A,B and C,respectively;(a2),(b2),and (c2)are regressions between coef ficients of Eq.(2)and cosine of azimuth angle for Hills A,B,and C,respectively;(a3),(b3),and (c3)are the distribution of SOC concentration estimated by Eq.(4)for Hills A,B,and C,respectively.Table 3Effects of slope aspects,depths and elevations on SOC concentration at the hill scale.SourceDFGeneral linear model Mixed linear model F valueSS%F value SS%Aspect 11414.58⁎⁎80.191421.61⁎⁎80.39Depth 1334.12⁎⁎18.94335.06⁎⁎18.95Elevation 114.36⁎⁎0.8110.77⁎⁎0.61Residuals4280.060.05DF,F,and SS%are degrees of freedom,F-statistic,and proportion of the variance explained by variable;the results were obtained from general linear model (GLM)and mixed linear model (MLM)analyses.⁎⁎P b 0.01.98M.Zhu et al./Catena 152(2017)94–102During the construction phase,we found that for each sampling hill in this study,signi ficant logarithmic relations of the SOC concentration with depth were observed at each aspect (Fig.2a1–c1).The R 2values of the regression functions varied from 0.58to 0.76,0.53to 0.87,and 0.59to 0.74on Hills A,B and C,respectively (Fig.2a1–c1).As shownin Table 4and Fig.2,the regression coef ficients of the SOC concentration vs.depth relations increased with increasing cosine of azimuth angle of aspects,following the exponential function.The R 2values of the regres-sion functions (i.e.,Eq.(3))on each hill were 0.99for a ,and 0.98for b .The SOC density at a depth h increased with increasing cosine of the azimuth angle of the slope aspect,following an exponential function (Table 5,Fig.3a1–c1).The R 2values of the regression functions (i.e.,Eq.(6))varied from 0.47to 0.90on the three hills.We observed margin-ally signi ficant exponential relations of the coef ficients a and b in Eq.(6)with depth on Hills A and B,and signi ficant exponential relations on Hill C (Fig.3a2–c2).The R 2values of the regression functions (i.e.,Eq.(7))varied from 0.97to 0.99.The coef ficients of Eqs.(4)and (8)for the three hills are shown in Table 6.The linear fits for the measured and estimated SOC indicated that Eqs.(4)and (8)were able to successfully explain the variation of SOC by the depths and slope aspects,with the slopes of the regression lines being close to 1,and the R 2values larger than 0.80(Fig.4).In addi-tion,we predicted the SOC density at 0–5,0–15,0–30,and 0–50cm on the SFS and NFS based on Eq.(8),and compared the estimates with pre-vious observations from Chen et al.(2016).The results showed that Eq.(8)was able to successfully predict the SOC density at different soil layers on the SFS and NFS observed in their study (Fig.5).ThelinearFig.3.Description of SOC density with azimuth angle of slope aspect and soil depth.(a1),(b1),and (c1)are regressions between SOCD h and the cosine of the azimuth angle for Hills A,B and C,respectively;(a2),(b2),and (c2)are regressions between coef ficients of Eq.(6)and soil depth for Hills A,B,and C,respectively;(a3),(b3),and (c3)are SOC density at different soil layers estimated by Eq.(8)for Hills A,B and C,respectively.Table 5Regression coef ficients of the SOCD h vs.aspect relations.HillDepth (cm)SOCD h =a e b cos(A )Coef ficient a Coef ficient b A50.4320.508150.3430.513300.2920.544500.2320.592B50.4990.455150.3680.543300.2920.647500.2170.780C50.4120.435150.3390.552300.2670.715500.2080.85899M.Zhu et al./Catena 152(2017)94–102fits between the estimates and observations from Chen et al.(2016)in-dicated that the R 2values were 0.94,0.93,and 0.93for Hills A,B,and C,respectively.According to Eqs.(4)and (8),we also predicted the distribution pat-tern on the three hills.The results show that the SOC concentration in-creased from the SFS to the NFS at all depths,and the rate of increase was lower on the SFS and NFS than on WFS (Fig.2a3–c3).In addition,the SOC density at 0–10,0–20,0–40,and 0–60cm increased from the SFS to the NFS,and the rate of increase was lower on the SFS and NFS than on the WFS (Fig.3a3–c3).4.Discussion4.1.Distribution patterns of SOCBoth SOC concentration and density increased from the SFS to NFS.Similar results were also obtained by other recent studies,which showed that the SOC concentration on the shady aspect (NFS)was sig-ni ficantly higher than other aspects (Sharma et al.,2011;Lenka et al.,2013;Huang et al.,2015).This distribution pattern was probably due to the heterogeneity of the soil temperature at the hill scale.In alpine re-gions,topographic obstructions and aspects affect the radiation distri-bution (Zhang et al.,2015).The potential annual direct incident radiation on the SFS was about 8%,37%and 93%higher than on the SWFS,WFS,and NFS,respectively (McCune and Keon,2002).Higher ra-diation resulted in higher soil temperature,which led to faster decom-position of soil organic matter,and consequently less accumulation of the organic carbon in soil on the SFS compared with the NFS (Kirschbaum,1995).In addition,the cover of grasslands increased from the SFS to WFS,and the vegetation type transformed to forests on the NFS (Table 1).The differences in vegetation cover and typemay also contribute to the distribution patterns of SOC along the aspect gradients.On the SFS,SWFS and WFS in this study,the SOC concentration and density tended to be higher at the lower elevations along each transect.This result was different from other studies that showed that the SOC in-creases with increasing elevation (Leifeld et al.,2005;Chen et al.,2016).This may be associated with the soil erosion along each transect.In this study,sampling positions (i.e.,1and 2)at higher elevations were at the shoulderslope and backslope positions of each transect,and the lower elevations sampling positions were at the footslope positions.The upper slope positions were generally eroded while the lower positions were depositional (McCarty and Ritchie,2002;Papiernik et al.,2005).Soil nutrients tend to accumulate in these depositional areas (Heckrath et al.,2005;Papiernik et al.,2007),thus the SOC is generally higher at the lower slope positions (Zhang et al.,2013;Sun et al.,2015).In our study region,the SFS,SWFS and WFS were occupied by grass-lands with cover b 0.7and suffered from slight to moderate soil erosion (He et al.,1992),soil erosion along these transects may enhance the ac-cumulation of SOC at lower positions,and this enhancement may mask the effect of elevation on SOC.4.2.Effects of slope aspects and soil depths on SOCThe slope aspects and depths in our study strongly affected the dis-tribution pattern of SOC.The GLM suggested that,at the hill scale,the variation of SOC concentration explained by elevation was much less than that explained by the slope aspects.Similar results were also ob-tained in Qilian Mountains by Chen et al.(2016),who indicated that,at a catchment scale,the aspect was able to explain 68.16%of the overall variation in SOC density at a soil depth of 0–50cm while the elevation explained only 29.33%.However,in our study,the effect of elevation was much tiny compared with Chen et al.(2016).The trivial effect of el-evation on SOC in our study was thus associated with the low relative elevations (b 100m)of the transects.In addition,compared with the other studies (Sharma et al.,2011;Huang et al.,2015;Sun et al.,2015;Lozano-García et al.,2016),the difference of SOC between the SFS and NFS in this study was much larger (close to fourfold).This was associat-ed with the strong slope aspect effects in the forest steppe zone of the Qilian Mountains,where the vegetation patterns are closely related to slope aspect,and represent a mosaic of grasslands and forests (Fig.1b).The tremendous difference of SOC along the aspect gradients also indicated that,to accurately estimate SOC storage in semiarid alpine re-gions,the slope aspect should be suf ficiently considered in SOC predic-tionmodels.parison between observations and estimates of SOC concentration (a)and density (b).Table 6Coef ficients of Eqs.(4)and (8)for the three hills.PropertiesHillCoef ficients c 1d 1c 2d 2e 1e 2SOC concentration (g kg −1)A 68.8710.77911.8190.861B 82.0780.68714.8700.640C 65.5130.69010.8100.556SOC density (kg m −2)A 0.2000.2820.4680.033−0.0410.027B 0.1860.393 1.543−1.129−0.048−0.008C0.1410.3161.217−0.856−0.031−0.017100M.Zhu et al./Catena 152(2017)94–102。

陆地污染英语作文Title: The Menace of Land Pollution。

Land pollution, a pressing environmental issue, poses significant threats to ecosystems, human health, and biodiversity. Addressing this challenge demands collective awareness, proactive measures, and sustainable practices.Firstly, land pollution encompasses various forms, including littering, industrial waste, agricultural runoff, and improper waste disposal. These activities introduce harmful substances like plastics, heavy metals, and chemicals into the soil, contaminating it and disruptingits natural balance. Consequently, fertile land becomes barren, affecting agricultural productivity and food security.Moreover, land pollution detrimentally impacts biodiversity. Contaminated soil adversely affects plant growth, leading to a decline in vegetation cover. This, inturn, disrupts habitats and threatens the survival of numerous species. Additionally, pollutants can enter the food chain, causing bioaccumulation and biomagnification, which pose risks to both wildlife and humans.Furthermore, land pollution significantly affects human health. Contaminated soil can leach harmful chemicals into groundwater, contaminating water sources and endangering public health. Moreover, airborne pollutants from landfills and industrial sites contribute to respiratory diseases and other health complications. Communities residing near polluted areas are particularly vulnerable, facing heightened risks of illnesses and ailments.To combat land pollution effectively, a multi-faceted approach is imperative. Firstly, stringent regulations must be enacted and enforced to control industrial emissions, waste disposal practices, and agricultural runoff. Additionally, promoting recycling and waste reduction initiatives can minimize the generation of waste and alleviate the burden on landfills. Public awareness campaigns play a crucial role in fostering environmentalconsciousness and encouraging responsible behavior towards waste management.Furthermore, implementing sustainable land management practices is essential for mitigating pollution and restoring degraded areas. Techniques such as afforestation, soil remediation, and organic farming help rejuvenate soil health and promote biodiversity conservation. Collaborative efforts involving governments, industries, communities, and environmental organizations are vital for implementing these strategies and achieving meaningful results.Education also plays a pivotal role in combating land pollution. Integrating environmental studies into school curricula fosters environmental literacy from an early age, empowering future generations to become stewards of the environment. Additionally, raising awareness through public outreach programs, workshops, and media campaigns educates communities about the impacts of land pollution and encourages environmentally responsible behavior.In conclusion, land pollution poses grave threats toecosystems, human health, and biodiversity. Addressing this issue requires concerted efforts at local, national, and global levels. By implementing stringent regulations, promoting sustainable practices, and fostering environmental awareness, we can mitigate the impacts of land pollution and pave the way for a healthier, more sustainable future.。