Bioleaching of heavy metals from red mud using Aspergillus niger

氮掺杂碳点的制备及在六价铬检测中的应用曾强;朱浩波;朱红艳;朱小利;戴昌雄;邓淳;何瑜;张修华;宋功武【摘要】以破壁灵芝孢子粉为碳源、尿素为含氮掺杂剂,采用一步超声法制备了氮掺杂荧光碳点(N-CDs),并将其作为荧光探针检测Cr6+.向碳点溶液中加入Cr6+后,碳点荧光发生了猝灭,表明碳点与Cr6+发生了作用,并在Cr6+浓度为0～300μmol·L-1范围内荧光强度变化值与Cr6+浓度表现出良好线性关系,相关系数为0.9818,检出限为0.3μmol· L-1.在实际样品检测中,回收率较好,为94％～102％,说明所制N-CDs可用于Cr6+的检测,具有较高的实用价值.【期刊名称】《化学与生物工程》【年(卷),期】2016(033)003【总页数】5页(P48-52)【关键词】Cr6+;灵芝孢子粉;荧光碳点;氮掺杂;荧光检测【作者】曾强;朱浩波;朱红艳;朱小利;戴昌雄;邓淳;何瑜;张修华;宋功武【作者单位】武汉红金龙印务股份有限公司,湖北武汉430056;武汉红金龙印务股份有限公司,湖北武汉430056;武汉红金龙印务股份有限公司,湖北武汉430056;武汉红金龙印务股份有限公司,湖北武汉430056;武汉红金龙印务股份有限公司,湖北武汉430056;湖北大学化学化工学院,湖北武汉430062;湖北大学化学化工学院,湖北武汉430062;湖北大学化学化工学院,湖北武汉430062;湖北大学化学化工学院,湖北武汉430062【正文语种】中文【中图分类】O613.71铬是一种重要的金属元素，广泛应用于电镀、制革、染料及冶金工业中[1]。

在环境中主要以Cr3+和Cr6+两种形式存在[2]。

铬的毒性与其所处化学价态有关[3]，Cr3+为人体所需微量元素[4]，主要功能为促进人体糖类[5]、蛋白质[6]和脂类的新陈代谢及人体生长发育[7-8]，而Cr6+对人体有毒，易穿透细胞并在细胞内沉积，其强氧化性可引起肾脏、肝脏、神经系统和血液的广泛病变[9]。

超富集植物吸收富集重金属的生理和分子生物学机制3李文学　陈同斌33(中国科学院地理科学与资源研究所环境修复室,北京100101)【摘要】　与普通植物相比,超富集植物在地上部富集大量重金属离子的情况下可以正常生长,其富集重金属的机理已经成为当前植物逆境生理研究的热点领域.尤其是近两年,随着分子生物学等现代技术手段的引入,关于重金属离子富集机理的研究取得了一定进展.通过与酵母突变株功能互补克隆到了多条编码微量元素转运蛋白的全长cDNA ;也从分子水平上研究了谷胱甘肽、植物螯合素、金属硫蛋白、有机酸或氨基酸等含巯基物质与重金属富集之间的可能关系.本文从植物生理和分子生物学角度简要评述超富集植物对重金属元素的吸收、富集、螯合及区室化的机制.关键词　超富集植物　重金属　生理学机制　分子生物学机制文章编号　1001-9332(2003)04-0627-05　中图分类号　X171.5　文献标识码　APhysiological and molecular biological mechanisms of heavy metal absorption and accumulation in hyperaccu 2mu altors.L I Wenxue ,CHEN Tongbin (L aboratory of Environmental Remediation ,Institute of Geographical Sciences and N atural Resources Research ,Chinese Academy of Sciences ,Beijing 100101,China ).2Chin.J.A p 2pl.Ecol .,2003,14(4):627～631.In comparison with normal plants ,hyperaccumulators have the ability to accumulate heavy metals in their shoots far exceeding those observed in soil ,without suffering from detrimental effects.With the help of molecular tech 2nologies ,the research on the mechanisms of heavy metal accumulation in hyperaccumulators has been made a great progress.A number of trace element trans porters have been cloned by functional complementation with yeast mutants defective in metal absorption.The relations between glutathione ,phytochelatins metallothioneins ,organic acids and heavy metals have been studied by molecular technologies.This review concentrated on the physiological and molecular mechanisms of heavy metal absorption and sequestration in hyperaccumulators.K ey w ords Hyperaccumulator ,Heavy metal ,Physiological mechanisms ,Molecular biological mechanisms.3国家自然科学基金项目(40071075)、中国科学院知识创新工程重点方向项目(K Z CX 22401202)和王宽诚博士后工作奖励基金资助.33通讯联系人.E 2mail :chentb @ 2002-07-05收稿,2002-11-28接受.1　引 言土壤重金属污染是一个重要的环境问题,传统的治理主要采用物理或化学方法,费用高,对大面积的污染效果差;与传统措施相比,植物修复技术以成本低、操作简单等优点而倍受青睐.广义上的植物修复是指利用植物去除土壤、水体或空气中重金属、有机污染物等污染物的技术,包含植物萃取(Phytoextraction )、根际过滤(Rhizofiltration )、植物挥发(Phytovolatilization )、植物固定(Phytostabilization )等技术,现在通常提到的植物修复主要是指植物萃取[32].超富集植物(Hyperaccumulator )是植物修复的基础,国际上已发现400多种超富集植物,国内对于超富集植物的研究相对较晚,研究较为系统的当属As 、Zn 等重金属的超富集植物[2,3,33].与普通植物相比,重金属离子进入超富集植物体内同样经过吸收/转运、富集/转化/矿化等生理生化过程,而且许多重金属离子进入植物体内的离子通道与必需营养元素相同,这就决定了超富集植物必然具有独特的生理代谢过程.关于这些过程的研究已经成为新的研究热点.本文对有关超富集植物吸收和富集重金属离子的生理及分子机制研究进行评述.2　重金属离子吸收的分子生物学机制 遏蓝菜属(Thlaspi L.)植物具有非常强的富集Zn 的能力,能够在地上部富集高达3%(干重)的Zn ,同时植物正常生长,没有表现出任何中毒症状,它已经成为研究重金属富集机理的模式植物之一.但无论是超富集植物或是普通植物,金属离子进入植物体内的第一步是根系吸收,也就是说吸收过程很可能是超富集植物富集重金属离子的第一个限速步骤.T.caerulescens 与T.arvense 同属于遏蓝菜属,T.caerulescens 能够富集Zn 而T.arvense 则不具此能力,通过比较它们对Zn 2+的吸收动力学发现:两者Km 值差异不大,但T.caerulescens 的Vmax 要比T.arvense 高3.5倍[21],表明T.caerulescens 富集Zn 2+的能力并非是与Zn 2+有更高的亲和力,而很可能是因为锌离子的流入量加大所致,也就是说在T.caerulescens 根系细胞膜上分布有更多的锌离子转应用生态学报　2003年4月　第14卷　第4期 CHIN ESE JOURNAL OF APPL IED ECOLO GY ,Apr.2003,14(4)∶627～631运蛋白.近年来随着分子生物学等现代技术手段的引入,人们对金属离子如何进入细胞有了新的认识.通过对酵母突变株进行功能互补克隆到了多条编码微量元素转运蛋白的全长cDNA,其中研究最多的是ZIP基因家族(ZRT,IRT-like Protein).ZIP基因家族分布非常广泛,在真菌、动物、植物等真核细胞中均发现了ZIP基因家族成员.ZIP基因编码的蛋白一般具有8个跨膜区,C2端和N2端的氨基酸均位于细胞膜外.此家族包含至少25个成员,z rt1、z rt2(zinc2regulated transporter)和irt1(iron2regulated transporter)是最早克隆到的ZIP基因.z rt1、z rt2均由酵母中获得,与Zn的吸收密切相关[36,37];irt1编码的蛋白主要位于拟南芥的根系,体内缺Fe时可诱导irt1表达[8].另一类与金属离子吸收有关的蛋白是Nramp基因家族(Natural resistance associated macrophage proteins).Nramp基因家族编码的蛋白一般具有12个跨膜区,这与ZIP基因家族明显不同.Nramp最初在哺乳动物中发现,植物中的研究主要集中于水稻(Oryz a sativa)和拟南芥(A rabidopsis).O2 ryz a sativa和A rabidopsis的Nramp基因家族分为2类,Os2 Nramp1、OsNramp3和AtNramp5属于一类,OsNramp2、At2 Nramp1、AtNramp2、AtNramp3与AtNramp4属于另一类. Nramp基因家族在植物中的功能现在仍不清楚,AtNramp3和AtNramp4能够维持A rabidopsis体内铁离子的平衡[29].此外,AtNramp3很可能与Ca2+的吸收有关,破坏AtNramp3基因可增加植物对Cd的耐性,过量表达则导致植物对Ca2+的超敏感性.对于超富集植物而言,Zn的吸收过程研究相对较清楚.通过与酵母突变株进行功能互补,Pence等[24]在具有富Zn 能力的T.caerulescen中克隆到z nt1.z nt1编码Zn2+转运蛋白,属ZIP基因家族,缺Zn和Zn供应充足条件下均可以在根系和叶片中高量表达,表明其可能是组成型表达;对于不具有富Zn能力的T.arvense而言,z nt1主要在缺Zn件下表达,供Zn时,表达明显受到抑制.这种表达方式的不同很可能是造成Thlaspi富Zn能力差异的主要原因之一.Assun2 cao等[1]的研究结果也表明Zn转运蛋白基因T.caerulescen 的表达量要远高于T.arvense.从Pence等[24]、Assuncao等[1]与Lasat等[21]的实验结果可以发现根系Zn转运蛋白基因的表达量与Thlaspi富集Zn的能力正相关,初步验证了吸收过程是超富集植物富集重金属离子的首个限速步骤的假设.但是目前还不能肯定转运蛋白是否在超富集植物吸收重金属方面起到决定性作用.譬如说,尽管z nt1、z nt2在T. caerulescen的表达量要远高于T.arvense,但是它们在具有不同富集能力T.caerulescen中的表达量几乎相同[1],即T.caerulescen富集能力的差异与吸收并无太大的相关性.造成此现象的原因很可能在于:(1)一般来说,转运蛋白由一个基因家族控制,而现在得到的克隆还不足以代表整个家族,许多未知的基因可能起到更为重要的作用,如在T. caerulescen就又克隆到z at基因,它与Zn2+的区室化(Se2questration)密切相关,但是此基因与ZIP基因家族明显不同,仅含有6个跨膜区[34];(2)对已知转运蛋白的性质研究还不清楚,金属离子转运蛋白对底物专一性不强,造成多种吸收途径同时对一种金属离子发挥作用,所以在进行具体的分子生物学研究时,必须清楚那些转运蛋白对该金属离子起作用;(3)现在转运蛋白的研究主要集中于根系,叶片中转运蛋白的研究相对较少,但是对超富集植物而言,重金属离子在地上部的含量要远远高于根系,即叶片中的转运蛋白很可能起到更为主要的作用.3　木质部运输 在木质部存在大量的有机酸和氨基酸,它们能够与金属离子结合,这种复合物是重金属离子在木质部中运输的主要形式.譬如在木质部,Fe主要是以柠檬酸铁的形式存在,Zn 主要是与柠檬酸或苹果酸结合,而Cu随着植物不同可与天冬酰胺酸、谷氨酸、组氨酸或烟碱结合,当然也有许多是以离子形态存在的,如Ca、Mg、Mn.在超富集植物中研究较多的为组氨酸.Kramer等[19]发现,组氨酸与A lyssum montanum 富集Ni的能力密切相关,当植物地上部Ni含量高时,木质部中组氨酸含量也较高,外源组氨酸的加入也能显著促进Ni装载入木质部,从而提高Ni向地上部的运输.然而,最近的研究表明,组氨酸反应很可能并不是Ni超富集植物的普遍机理.Persans等[25]在研究Ni的超累积植物Thlaspi geosingense时并没有发现His反应,同时他们克隆了控制His 合成的关键酶基因thg1、thb1、thd1,其表达量并没有随着Ni用量的增加而升高. 重金属由根系进入木质部至少需要3个过程:进入根细胞,由根细胞运输到中柱,装载到木质部.在内皮层由于凯氏带的存在,使得共质体运输在重金属进入木质部的过程中起到主导作用.在共质体运输中起关键作用的是膜转运蛋白,然而直到现在还没有在木质部中克隆到与重金属离子运输相关的基因,这方面的研究,尤其是在研究超富集植物时应该引起充分的重视.与普通植物相比,超富集植物能够高效、迅速地把重金属离子由根系运输到地上部,而通过凯氏带是重金属离子进入木质部主要屏障之一,探明此过程,将有利于提高植物修复的效果.4　对金属离子的解毒机制411　谷胱甘肽(GSH) 许多金属离子是植物必需的微量养分,它们参与植物体内众多的生理代谢过程.但如果含量过高,尤其是具有氧化还原活性的金属,会对植物产生毒害作用,这种毒害作用很可能是由于自由基的形成造成的.GSH含巯基,具有很强的氧化还原特性,可有效地清除活性氧等自由基,因此GSH在植物抗逆境胁迫中起重要作用.GSH为三肽,结构通式为γ2 G lu2Cys2G ly,合成主要通过两步依赖于A TP的反应完成,γ2 EC合成酶和GSH合成酶是其中的关键酶.γ2EC合成酶由gsh1编码,GSH合成酶由gsh2编码,gsh1与gsh2在拟南芥826应　用　生　态　学　报 14卷基因组中均以单拷贝的形式存在. 正常条件下,GSH的合成依赖于半胱氨酸的活性,同时存在明显的反馈抑制现象,表明由γ2EC合成酶催化的反应是整个合成的限速步骤.重金属胁迫条件下,重金属离子激活植物螯合素的合成,消除了GSH的反馈抑制作用,由GSH 合成酶催化的反应也成为限速步骤,此时如果加强gsh2的表达,则既可增加植物螯合素的合成又能避免GSH的耗竭,从而缓解重金属胁迫.Zhu等[38,39]的实验结果验证了此假设.他把大肠杆菌的gsh1与gsh2分别转入到印度芥菜(B rassica juncea),发现印度芥菜对Cd2+的耐性与富集能力均有明显增加,且耐性和富集能力还与gsh2的表达正相关.然而,Foyer等[10]把gsh2转入白杨树(Populus)后,白杨树抗氧化胁迫的能力(光抑制)并没有增加;G oldsbrough等[13]的结果也表明gsh2转入野生型的拟南芥后并不能增加其对Cd的抗性.由此可见,如何通过基因工程改造GSH,以增加植物对重金属的耐性和富集能力还有待于进一步研究.412　植物螯合素(PCs) 植物螯合素(PCs,=cadystins in S.pombe)由植物体内一系列低分子量、能够结合金属离子的多肽组成,其结构通式为(γ2G lu2Cys)n2G ly(图1),一般来讲,n为2～5,最高可达11[5].现已发现多种PC的同功异构体,主要是C端的G ly 被β2Ala、Ser取代形成.原来认为植物螯合素仅存在于植物中,但是随着研究的深入,陆续在线虫、蚯蚓等克隆到PC合成酶的类似基因. PCs不能由基因直接编码,必须在PCs合成酶的催化下完成[14].PC合成酶为四聚体,分子量95000道尔顿,等电点在p H4.8附近,最适反应温度和p H分别为35o℃、7.9[14].然而,由克隆到的编码PCs的全长cDNA推测的结果与此不符,推测结果表明PCs不是多聚体,分子量为42000～70000道尔顿,这种偏差很可能由于在Grill等提纯的酶中PCs并不是主要成分造成的.不同重金属离子诱导PCs合成的能力有很大差别[15],一般为Cd2+>Pb2+>Zn2+>Sb3+>Ag+> Hg2+>As5+>Cu+>Sn2+>Au3+>Bi3+;不同重金属离子诱导PC合成酶活性的能力与诱导PCs合成的能力稍有不同[35]:Cd2+>Ag+>Pb2+>Cu+>Hg2+>Zn2+>Sn2+> Au3+>As5->In3+>Tl3+>G e4+>Bi3+>G a3+.关于PCs 功能研究得相对清楚的是PCs与Cd之间的关系(图2).现图1　植物螯合素的化学结构示意图Fig.1Chemical structure of phytochelatin.已明确PCs在植物解Cd毒中起到重要作用,PCs2Cd复合物是Cd由细胞质进入液泡的主要形式.正是由于PCs在重金属离子区室化中所起的重要作用,近年来PCs已成为植物抗重金属胁迫的研究热点之一. 目前PCs的分子生物学研究基本集中于普通植物或耐性植物,而有关超富集植物的研究相对较少.Schmoger等[28]在用As处理过的蛇根木(Rauvolf ia serpentina)悬浮细胞及拟南芥幼苗中发现了PCs,Hartley2Whitaker等[17]在绒毛草(Holcus lanatus)上也证实了上述现象.但这些植物多属于耐性植物.Ebbs等[7]的实验表明,无论是否具有富集能力, Thlaspi用Cd处理后都会有大量PCs的合成,但是T.ar2 vense中PCs的总量要高于T.caerulescens,说明PCs与植物富Cd能力之间并无太大的关系.由于PCs在超富集植物中的研究还很少,所以PCs在超富集植物是否起到重要作用还有待于深入研究. Cobbett、Rea和等3个研究小组于1999年分别在拟南芥、小麦、酵母中克隆到了编码PC合成酶的全长cDNA.其中,通过对拟南芥cad1突变株(含有与野生型相似的GSH含量,但不含PC)定位克隆获得At PCS1[16],小麦耐Cd基因At PCS1与TaPCS1主要是通过与酵母突变株功能互补得到[4,30].对PC合成酶相应的全长cDNA对齐比较发现其保守区位于N端,同一性高达40%.长时间Cd2+处理cad1突变株也没有发现PCs的合成,表明PCs的合成可能是由单基因控制[18].但随着拟南芥基因组测序的完成,发现了与At PCS1高度同源的At PCS2基因[16],其功能尚不清楚,但与At PCS1相比,其表达量非常低.但植物在长期的进化历程中把At PCS2作为功能基因保留下来,尽管其在正常条件下表达量很低,可以想象在某些器官或环境下,At PCS2基因的表达肯定会起到重要作用.图2　以Cd为例说明谷胱甘肽、植物螯合素在抗重金属胁迫中的作用(+表示增加基因表达或酶活性,-表示减少基因表达或酶活性, HM T1表示位于液泡膜上的PC2Cd转运蛋白),参见Cobbert[5]并作修改Fig.2Function of GSH and PC in the metal tolerance of plants under metal stress(+and2indicate positive and negative regulation of enzyme activities or gene expression,respectively;HM T1is a vacuolar meme2 brane transporter of PC2Cd complex;revised from the figure of Cob2 bert[5]).413　金属硫蛋白(M T) 金属硫蛋白(Metallothioneins)是自然界中普遍存在的一种低分子量、富含半胱氨酸的蛋白质.它与PCs的本质区别在于M T由基因直接编码,而PCs在PCs合成酶的催化下完成.与PCs一样,金属硫蛋白能够通过巯基与金属离子结合,从而降低重金属离子的毒性,它对于Zn2+和Cu2+的解毒效9264期 李文学等:超富集植物吸收富集重金属的生理和分子生物学机制 果尤为明显[23]. 植物中首先鉴定的M T是Ec蛋白,它由小麦成熟胚芽中分离得到.在植物中已发现大约50种M T,根据半胱氨酸残基的排列方式,可以将其分为Ⅰ型、Ⅱ型、Ⅲ型和V型,大多属于Ⅰ型和Ⅱ型.Ⅰ型中的半胱氨酸残基仅有Cys2Xaa2 Cys一种排列方式;Ⅱ型中的半胱氨酸残基有两种排列方式,分别为Cys2Cys、Cys2Xaa2Xaa2Cys.编码I型M T的cDNA 在根系的表达水平较高,编码Ⅱ型M T的cDNA主要在叶片表达. 金属硫蛋白极易水解,尤其植物中的金属硫蛋白氨基酸链比较长,极易在半胱氨酸区水解,同时金属硫蛋白在有氧的条件下非常不稳定,所以难以获得相应蛋白质的资料,目前仅对小麦Ec蛋白及拟南芥M T1、M T2编码的蛋白进行了纯化,这就限制了对M T类似基因功能的研究.Murphy 等[22]证实Cu2+诱导拟南芥M T2表达,而且表达强度与不同基因型抗Cu胁迫的能力密切相关;Nathalie等[13]的研究结果也证实Cu的耐性植物Silene v ulgaris耐Cu胁迫的特性与M T2b的表达紧密联系.王剑虹等[31]在重金属耐性植物紫羊茅草(Festuca rebra)中克隆到mc M T1的全长cD2 NA,此基因编码70个氨基酸,含有12个Cys残基,在N端和C端分别含有3个Cys2Xaa2Cys结构,将此基因转入到酵母M T基因缺失突变株中发现,mc M T1的表达增加了酵母细胞对Cu、Cd和Pb的抗性.在拟南芥和蚕豆中,M T主要在毛状体中表达[9,12],而Cd等许多有毒重金属离子也在毛状体中累积[27],暗示M T和重金属累积有某种联系.414　细胞壁的固持与区室化作用 植物细胞壁残基对阳离子有高亲和力,可以影响重金属离子向细胞内扩散速率,从而影响金属离子的吸收.比较黄花茅(A nthox anthum odoratum)悬浮细胞和原生质体固Pb 能力发现,Pb浓度对从耐Pb细胞克隆分离的悬浮细胞无太大影响,而原生质体的死亡率上升,相应地,从Pb敏感细胞克隆分离的悬浮细胞和原生质体对Pb极其敏感,表明细胞壁在A nthox anthum odoratum抗Pb胁迫中起到重要作用[26].需要明确的是,细胞壁对金属的固定作用不是一个普遍的抗金属毒害的机制,例如抗Zn毒和Zn敏感型菜豆的细胞壁物质表现出相似的亲和力,同时细胞壁有一定的金属容量,而超富集植物能够在地上部富集大量的重金属离子,暗示细胞壁不可能在超富集植物中起到重要作用.最近的研究表明,区室化作用与超富集植物富集重金属离子的能力密切相关.就Thlaspi而言,具有富集能力的T.geosingense液泡中Ni的含量要比不具有富集能力的T.arvense高1倍[20]; Frey等[11]也证实Zn在T.caerulescens中主要分布于表皮细胞液泡中.但区室化作用是否为超富集植物富集重金属离子的一个普遍机理还需对新发现的超富集植物进一步研究才能确定.5　研究展望 关于超富集植物富集重金属离子的研究虽然取得了一定进展,但至今对其分子和生理机制仍不是很清楚,研究人员的看法也存在明显的分歧.在把超富集植物用于实践的过程中,首先要研究清楚对超富集植物富集的生理基础,譬如重金属离子如何进入根细胞,在木质部如何被运输,在叶片中如何分布;其次要注意不同生理过程的联系,就吸收而言,它其实是根系吸收与体内再分配的有机结合,所以在利用基因工程方法增加重金属离子吸收量时,不仅要考虑到增加根系的吸收位点,提高转运蛋白底物的专一性,同时要注意细胞器,尤其是液泡膜上与重金属离子区室化相关膜蛋白的表达,只有这样,才会达到比较好的效果;最后要强调的是学科交叉与渗透,Dhankher等[6]将细菌中的砷酸盐还原酶ArsC 基因和γ2谷氨酰半胱氨酸合成酶(γ2ECS)在拟南芥的叶子中表达,这样运输到地上部的砷酸盐在砷酸盐还原酶的作用下转化成亚砷酸盐,γ2ECS表达可增加一些连接重金属(如亚砷酸盐)并解除其毒性的化合物,将这些复合物限制在叶子中,从而使植物能够积累并忍耐不断增加的As含量.参考文献1　Assuncao A G L,Martins PDC,Polter SD,et al.2001.Elevated expression of metal transporter genes in three accessions of the met2 al hyperaccumulator Thlaspi caerulescens Plant Cell Envi ron,24: 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J2H(王剑虹),Ma M(麻　密).2000.Biological mecha2 nisms of phytoremediation.Chi n B ull Bot(植物学通报),17(6): 504～510(in Chinese)32　Wei C2Y(韦朝阳),Chen T2B(陈同斌).2001.Hyperaccumu2 lators and phytoremediation of heavy metal contaminated soil:a re2 view of studies in China and abroad.Acta Ecol Si n(生态学报),21(7):1196～1203(in Chinese)33　Wei C2Y(韦朝阳),Chen T2B(陈同斌).2002.The ecological and chemical character of plants in arsenic abnormal areas.Acta Phytoecol Si n(植物生态学报),26:695～700(in Chinese)34　Zaal BJ VD,Neuteboom L W,Pinas J E,et al.1999.Overexpres2 sion of a novel Arabidopsis gene related to putative zinc2transporter genes from animals can lead to enhanced zinc resistance and accu2 mulation.Plant Physiol,119:1047～105535　Zenk MH.1996.Heavy metal detoxification in higher plants—a review.Gene,179:21～3036　Zhao H,Eide D.1996a.The yeast ZRT1gene encodes the zinc transporter protein of a high affinity uptake system induced by zinc limitation.Proc N atl Acad Sci,93:2454～245837　Zhao H,Eide D.1996b.The ZRT2gene encodes the low affinity zinc transporter in S accaromyces cerevisiae.J Biol Chem,271: 23203～2321038　Zhu Y L,Pilon2Smits EAH,Jouanin L.1999.Overexpression of glutathione synthetase in Indian mustard enhances cadmium accu2 mulation and tolerance.Plant Physiol,119:73～7939　Zhu Y L,Pilon2Smits EAH,Tarun AS,et al.1999.Cadmium tol2 erance and accumulation in Indian mustard is enhanced by overex2 pressingγ2glutamylcysteine synthetase.Plant Physiol,121:1169～1177作者简介　李文学,男,1973年生,博士后.主要从事植物营养遗传与重金属污染生态学研究,在国内外发表论文8篇. E2mail:liwx@1364期 李文学等:超富集植物吸收富集重金属的生理和分子生物学机制 。

1　问题的提出在有关蛋白质性质的教学中，教师往往是通过直观的变性蛋白质沉淀的现象，帮助学生认识到重金属盐会使蛋白质变性。

然而，一些教师在教学实验中发现，硫酸铜使蛋白质变性产生的沉淀，会溶解在过量的硫酸铜溶液中，教师对此现象难以自圆其说，陷入了非常尴尬的窘境。

本研究尝试运用多种重金属盐进行变性蛋白质沉淀实验时，发现往鸡蛋清溶液中加入过量的硫酸锌溶液或硫酸铜溶液，会使蛋白质沉淀溶解。

过量的重金属盐溶液为什么会使蛋白质沉淀溶解？对于该问题的解释，已有的文献包含理论探讨与实验研究两类：1）理论探讨的文献指出，Cu2+、Zn2+造成的蛋白质沉淀源于盐析作用而不是变性[1]；2）实验探究的文献指出，Cu2+引起蛋白质沉淀溶解的主要原因是体系pH变化影响了蛋白质的溶解度[2]。

鉴于此，本研究设计了一系列的化学实验，旨在解决以下3个问题：1）Cu2+、Zn2+的蛋白质沉淀是由于盐析还是变性?2）除Cu2+外，体系pH的变化是否会导致Zn2+、Ag+的蛋白质沉淀溶解？3）如何防止过量的重金属盐溶液使变性蛋白质沉淀溶解？2　实验方案2.1　实验仪器台秤、烧杯、玻璃棒、100mL容量瓶、试管、吸量管、力辰科技PH-100型pH测试笔。

2.2　实验试剂鸡蛋清溶液：用台秤称取5.0g鸡蛋清，加水至100.0g，搅拌，用4层纱布过滤，得到澄清透明鸡蛋清溶液（pH =9.38）。

其他试剂：浓硫酸、浓硝酸；分析纯的硫酸铜、硝酸银、硫酸锌。

2.3　正式试验实验1：探究Cu2+、Zn2+的蛋白质沉淀是由于盐析还是变性。

①取两支试管编号1、2号管，分别加入2mL 鸡蛋清溶液，1号试管中滴入3~4滴5%硫酸铜溶液，2号试管中滴入3~4滴5%硫酸锌溶液，观察到两支试管中均出现白色沉淀。

②往1、2号试管中分别加入4mL水，观察到两支试管内的沉淀均不溶解。

实验2：探究pH的变化是否会导致Cu2+、Zn2+、Ag+的蛋白质沉淀溶解。

①取三个烧杯，编号为A1、B1、C1，分别量取20mL的蛋清溶液，按表1分别加入重金属盐溶液，观察现象并测量pH。

高一化学金属英语阅读理解25题1<背景文章>Iron is one of the most abundant elements on Earth. It has many important properties. Iron is a solid at room temperature and has a shiny grayish appearance. It is very strong and durable, which makes it useful for many applications.One of the most common uses of iron is in the construction industry. Iron is used to make steel, which is then used to build bridges, buildings, and other structures. Steel is strong and can withstand a lot of weight and stress.Iron also has important chemical properties. It reacts with oxygen to form iron oxide, also known as rust. Rust is a reddish-brown substance that can weaken iron and cause it to deteriorate. To prevent rust, iron is often coated with a protective layer, such as paint or zinc.Another important compound of iron is iron sulfide. Iron sulfide is found in many minerals and is used in the production of sulfuric acid. Iron sulfide is also important in the environment, as it can help to remove heavy metals from contaminated soil and water.Iron is also essential for life. It is a key component of hemoglobin, a protein in red blood cells that carries oxygen from the lungs to the rest ofthe body. Without iron, the body cannot produce enough hemoglobin, which can lead to anemia.In conclusion, iron is a very important element with many useful properties and applications. It is essential for life and plays a crucial role in many industries.1. Iron is a solid at room temperature and has a ____ appearance.A. shiny blackishB. shiny grayishC. dull blackishD. dull grayish答案：B。

Uncovering the Origin of MetallurgyMetallurgy is the science and technology of extracting metals from their ores, refining them, and preparing them for use. It is a crucial aspect of human civilization and has played a significant role in shaping our world. The origin of metallurgy is a topic of great interest to historians, archaeologists, and scientists alike. In this essay, we will explore the different perspectives on the origin of metallurgy and try to uncover the truth behind this fascinating subject. One perspective on the origin of metallurgy is that it emerged independently in different parts of the world. This theory suggests that humans discovered the properties of metals through trial and error and developed the necessarytechniques to extract and refine them. This is supported by the fact that early metallurgy was found in several regions, including the Middle East, Asia, andSouth America. For example, the ancient Egyptians were known to have used copper and gold for decorative purposes, while the people of the Andes used copper to create intricate jewelry and ornaments. Another perspective on the origin of metallurgy is that it was developed through cultural diffusion. This theory suggests that metallurgy was first developed in one region and then spread toother parts of the world through trade and migration. For example, some historians believe that metallurgy was first developed in the Middle East and then spread to Europe and Asia. This is supported by the fact that the earliest known metal objects were found in the Middle East, such as the copper beads from the 6th millennium BCE found in the area now known as Iraq. A third perspective on the origin of metallurgy is that it was developed as a result of environmental factors. This theory suggests that the availability of certain metals in a particularregion led to the development of metallurgy in that area. For example, the abundance of copper in the Middle East and the Andes may have led to the development of early metallurgy in those regions. Similarly, the availability of iron in certain parts of Africa may have led to the development of ironworking in those areas. Regardless of the origin of metallurgy, it is clear that it played a crucial role in the development of human civilization. The ability to extract and refine metals allowed humans to create tools and weapons that were stronger and more durable than those made from stone or wood. This, in turn, led to thedevelopment of agriculture, trade, and the rise of civilizations. In conclusion, the origin of metallurgy is a fascinating subject that has captured the attention of historians, archaeologists, and scientists for centuries. While there are different perspectives on how metallurgy first emerged, it is clear that it played a crucial role in shaping our world. The ability to extract and refine metals allowed humans to create tools and weapons that were stronger and more durable, leading to the development of agriculture, trade, and the rise of civilizations. As we continue to uncover new evidence about the origin of metallurgy, we will gain a deeper understanding of our shared history and the remarkable achievements of our ancestors.。

铝酸三钙对硫酸根的去除及其作用机制相明雪;刘强;马若男;章萍【摘要】通过固相反应法制备铝酸三钙(C3A),研究了C3A对硫酸根(SO2-4)的去除效果,并探索了pH对SO2-4去除效果的影响,结合C3A对SO2-4反应前后产物的SEM、XRD和FT-IR等表征手段探讨了其对SO2-4的吸附作用机制.结果表明:C3A对SO2-4的吸附动力学符合准二级动力学方程.等温吸附符合Langmuir 等温吸附模型,在45 ℃、pH=7.0时,最大理论吸附量为4.75 mmol·g-1.在25 ℃下,反应最适pH为12,最大吸附量可达3.88 mmol·g-1.C3A去除SO2-4的作用机制为C3A水化过程中释放出Ca2+与SO2-4的沉淀作用及水化产物CaAl-LDH层间的阴离子交换作用.%Tricalcium aluminate(C3A)was prepared by solid phase reaction method and the removal efficien-cy of SO2-4 by C3A was investigated.In order to understand the adsorption mechanism,the samples were character-ized by SEM,XRD and FT-IR.Results showed that the experimental data was best fitted to the pseudo-second-or-der kinetics model,the adsorption process was consistent with Langmuir adsorption isotherm model,the C3A adsor-bent has an adsorption capacity of 4.75 mmol·g-1when the initial pH of solution was 7,with temperature around at 45 ℃.Furthermore,the optimum pH for the process was 12,and the amount of SO2-4 removel by C3A reached 3.88 mmol·g-1at25 ℃.Combine d with the results of the modern technology analysis,it was revealed that the mechanism of the removal of SO2-4 by C3A was the negative ion-exchange between SO2-4 and OH-as well as SO2-4 precipitation with Ca2+.【期刊名称】《南昌大学学报（工科版）》【年(卷),期】2017(039)003【总页数】6页(P219-223,230)【关键词】C3A;SO2-4;吸附;溶解-再沉淀;离子交换【作者】相明雪;刘强;马若男;章萍【作者单位】南昌大学资源环境与化学工程学院,江西南昌330031;南昌大学资源环境与化学工程学院,江西南昌330031;南昌大学资源环境与化学工程学院,江西南昌330031;南昌大学资源环境与化学工程学院,江西南昌330031;南昌大学鄱阳湖环境与资源利用教育部重点实验室,江西南昌330047【正文语种】中文【中图分类】TQ133.1硫酸根离子是工业废水中常见的阴离子，大量存在于矿山、冶金、食品及医药等行业废水中[1-3]。

Adsorption of heavy metal ion from aqueous single metal solutionby chemically modified sugarcane bagasseOsvaldo Karnitz Jr.a ,Leandro Vinicius Alves Gurgel a ,Ju´lio Ce ´sar Perin de Melo a ,Vagner Roberto Botaro a ,Taˆnia Ma ´rcia Sacramento Melo a ,Rossimiriam Pereira de Freitas Gil b ,Laurent Fre´de ´ric Gil a,*aDepartamento de Quı´mica,Instituto de Cie ˆncias Exatas e Biolo ´gicas,Universidade Federal de Ouro Preto,35400-000Ouro Preto,Minas Gerais,BrazilbDepartamento de Quı´mica,Instituto de Cie ˆncias Exatas,Universidade Federal de Minas Gerais,31270-901Belo Horizonte,Minas Gerais,BrazilReceived 22November 2005;received in revised form 28April 2006;accepted 2May 2006Available online 14July 2006AbstractThis work describes the preparation of new chelating materials derived from sugarcane bagasse for adsorption of heavy metal ions in aqueous solution.The first part of this report deals with the chemical modification of sugarcane bagasse with succinic anhydride.The carboxylic acid functions introduced into the material were used to anchor polyamines,which resulted in two yet unpublished modified sugarcane bagasse materials.The obtained materials were characterized by elemental analysis and infrared spectroscopy (IR).The sec-ond part of this reports features the comparative evaluation of the adsorption capacity of the modified sugarcane bagasse materials for Cu 2+,Cd 2+,and Pb 2+ions in aqueous single metal solution by classical titration.Adsorption isotherms were studied by the Freundlich and Langmuir models.Ó2006Elsevier Ltd.All rights reserved.Keywords:Adsorption;Modified sugarcane bagasse;Polyamines;Isotherm;Heavy metals1.IntroductionWater pollution is a major environmental problem faced by modern society (Baird,1995)that leads to eco-logical disequilibrium and health hazards (Kelter et al.,1997).Heavy metal ions such as copper,cadmium,lead,nickel,and chromium,often found in industrial waste-water,present acute toxicity to aquatic and terrestrial life,including humans.Thus,the discharge of effluents into the environment is a chief concern.The methods commonly used to remove toxic heavy metal from municipal and industrial wastewater are based on the adsorption of ions onto insoluble compounds and the separation of the sed-iments formed.Many efforts have been made recently tofind cheaper pollution control methods and materials(Panday et al.,1985;Ali and Bishtawi,1997;Acemiog˘lu and Alma,2001).The new material world trends point to the importance of using industrial and agricultural residues as production starting materials.Reusing and recycling these residues can minimize the environmental problems associated with their build-up and reduce the use of noble starting materi-als.This trend has contributed to the reconsideration of the use of traditional biomaterials such as natural lignocellu-losic fibers to substitute synthetic polymers,for example,since in many cases they have a better performance.Brazil is the world leading producer of sugarcane for both the alcohol and the sugar industries.These industries produce a large amount of sugarcane bagasse and although it is burned to produce energy for sugar mills,leftovers are still significant.Thus,on account of the importance of0960-8524/$-see front matter Ó2006Elsevier Ltd.All rights reserved.doi:10.1016/j.biortech.2006.05.013*Corresponding author.Tel.:+553135591717;fax:+55315511707.E-mail address:laurent@iceb.ufop.br (L.F.Gil).Bioresource Technology 98(2007)1291–1297bagasse sugar as an industrial waste,there is a great interest in developing chemical methods for recycling it.Sugarcane bagasse has around50%cellulose,27%polyoses,and23% lignin(Caraschi et al.,1996).These three biological poly-mers have many hydroxyl and/or phenolic functions that can be chemically reacted to produce materials with new properties(Xiao et al.,2001;Navarro et al.,1996).Despite the many studies of the chemical modification of cellulose published around the world in this area(Gurnani et al.,2003;Gellerested and Gatenholm,1999),only a few have investigated the modification of bagasse sugar(Krish-nan and Anirudhan,2002;Orlando et al.,2002).This work describes the preparation and the evaluation of new chelating materials from sugarcane bagasse to adsorb heavy metal ions in aqueous solution.In a prelimin-ary study,it has been chosen to study the adsorption of Cu2+,Cd2+,and Pb2+.Thefirst part of this work describes the modification of sugarcane bagasse with succinic an-hydride to introduce carboxylic functions to sugarcane bagasse and the chemical introduction of commercial linear polyamine via the formation of amide functions.It is well known that polyamines have powerful chelating properties, mainly towards ions such as Cu2+,Zn2+,and Pb2+(Bian-chi et al.,1991;Martell and Hancock,1996).The second part of this work evaluates the adsorption of Cu2+,Cd2+,and Pb2+onto three modified sugarcane bag-asses(MSBs)from aqueous single metal ion solutions by classical titration.The results were analyzed by the Lang-muir and Freundlich models(Ho et al.,2005).2.Methods2.1.MaterialsPolyamines ethylenediamine3and triethylenetetramine 4were used in this work.Succinic anhydride,1,3-diiso-propylcarbodiimide(DIC),and triethylenetetramine,from Aldrich,were used without purification.Ethylenediamine and dimethylformamide were distilled before use.Pyridine was refluxed with NaOH and distilled.2.2.Sugarcane bagasse preparationSugarcane bagasse was dried at100°C in an oven for approximately24h and nextfiber size was reduced to pow-der by milling with tungsten ring.The resulting material was sieved with a4-sieve system(10,30,45,and60mesh). Then,the material was washed with distilled water under stirring at65°C for1h and dried at100°C.Finally,it was washed anew in a sohxlet system with n-hexane/ ethanol(1:1)as solvent for4h.2.3.Synthesis of MSBs1and2Washed and dried sugarcane bagasse(5.02g)was trea-ted with succinic anhydride(12.56g)under pyridine reflux (120mL)for18h.The solid material wasfiltered,washed in sequence with1M solution of acetic acid in CH2Cl2, 0.1M solution of HCl,ethanol95%,distilled water,and finally with ethanol95%.After drying at100°C in an oven for30min and in a desiccator overnight,MSB1(7.699g) was obtained with a mass gain of53.4%.MSB2was obtained by treatment of1with saturated NaHCO3solu-tion for30min and afterwards byfiltering using sintered filter and washing with distilled water and ethanol.2.4.Synthesis of MSBs5and6The process used to introduce amine functions was the same as that used to prepare MSB5and6.MSB1was trea-ted with5equiv of1,3-diisopropylcarbodiimide(DIC)and 6equiv of polyamine in anhydrous DMF at room tempera-ture for22h under stirring.Afterfiltration,the materials were washed with DMF,a saturated solution of NaHCO3, distilled water,andfinally with ethanol.Next,they were dried at80°C in an oven for30min and in a desiccator overnight.2.5.Kinetic study of metal ion adsorption of MSBs2,5,and6Experiments with each material and metal ion were per-formed to determine the adsorption equilibrium time from 10to90min in10min intervals.The amount of100mg MSB was placed in a250-mL Erlenmeyer with100.0mL metal ion solution with concentration of200mg/L under stirring.The experiments were done at pHs5.8for Cu2+, 7.0for Cd2+,and6.2for Pb2+,optimal values to obtain the best adsorption.To adjust pH values,was added NaOH solution(0.01mol/L)into metal solutions with MSB.Afterfiltration,metal ion concentration was deter-mined by EDTA titration.2.6.pH study of metal ion adsorption of MSBs2,5,and6Experiments with each material and metal ion were per-formed to determine the effect of pH on ion adsorption.An amount of100mg MSB was placed into a250-mL Erlen-meyer with100.0mL of metal ion solution200mg/L under stirring.pH was calibrated with HCl or NaOH solutions (0.1–1.0mol/L).The reaction times used were30min (MSB2)or40min(MSB5and6)for Cu2+and Cd2+, and40min(MSB2)or50min(MSB5and6)for Pb2+. Metal ion concentration was determined afterfiltration by EDTA titration.No significative variation of pH was observed at the end of each experiment.2.7.Adsorption isotherms of MSBs2,5,and6Experiments were performed for each material and metal ion to determine adsorption isotherms.In each experiment,100mg of MSB was placed into a250-mL Erlenmeyer with100.0mL of metal ion solution in specific concentrations(between200mg/L and400mg/L)under stirring.Each experiment was performed at the pH of1292O.Karnitz Jr.et al./Bioresource Technology98(2007)1291–1297larger ion adsorption during the time necessary for equilib-rium (Tables 3and 4).After filtration,the metal ion con-centration was determined by EDTA titration.2.8.Characterization of the new obtained materials MSB 1,2,5,and 6were characterized by IR spectro-scopy in a Nicolet Impact 410equipment with KBr.Elemental analyses were accomplished in Analyzer 2400CHNS/O Perkin Elemer Series II.3.Results and discussion3.1.Synthesis of MSBs 1,2,5,and 6The synthesis route used to prepare MSBs 1,2,5,and 6are presented in Scheme 1.Prewashed sugarcane bagasse was succinylated for various periods of time.The degree of succinylation of the bagasse fibers was determined by measuring the quantity of acid function.The results are shown in Fig.1.The concentration of carboxylic functions per mg of bagasse was determined by retro titration.For this,MSB 1was initially treated with an excess solution of NaOH (0.01mol/L)for 30min.Soon afterwards the material was filtered and the obtained solution was titrated with an HCl solution (0.01mol/L).The highest degree of succinylation was reached after 18-h ing this reaction time,sugarcane bagasse was succinylated to pro-duce MSB 1,which presented a weight gain of 54%and a concentration of carboxylic acid function per mg of 3.83·10À6mol.Next,MSB 1was treated with a saturated NaHCO 3solution to produce MSB 2.Starting from MSB 1,two polyamines were introduced:ethylenediamine 3and triethylenetetramine 4.The method-ology used to introduce the polyamines was the same for the two MSBs 5and 6,as shown in Scheme 1.Concentra-tions of 2.4·10À6mol (5)and 2.6·10À6mol (6)of amine function per mg of material were determined by back titra-tion with excess HCl solution.The introduction of the amine functions was also verified by IR spectroscopy (Table 1)and elemental analysis (Table 2).3.2.Characterization of MSBs 1,5,and 6Characterization of carboxylated MSB 1was accom-plished by IR spectroscopy.The spectrum of unmodified sugarcane bagasse and MSB 1are presented in Fig.2.The spectrum of MSB 1displayed two strong bands at 1740and 1726cm À1in relation to that of unmodified sug-arcane bagasse.This demonstrated the presence of two types of carbonyl functions,one relative to carboxylic acid and another relative to the ester.The acid and ester IR bands indicate that succinic anhydride acylated theO.Karnitz Jr.et al./Bioresource Technology 98(2007)1291–12971293hydroxy group of bagasse to generate an ester bond with consequent release of a carboxylic acid functional group.The spectra of MSBs5and6(Figs.3and4,respectively) showed three new strong bands at1550–1650cmÀ1(see data in Table1)corresponding to the presence of amide and amine functions,and one band at1060cmÀ1 corresponding to C–N stretch.The bands at1635and 1650cmÀ1(Fig.3)correspond to the axial deformation of the carbonyl of the amide function and the angular deformation of the N–H bond of the amine function.The band at1575cmÀ1corresponds to the angular deformation of the N–H bond of the amide function.The band at 1159cmÀ1(Fig.4)corresponds to the asymmetric stretch of C–N–C bond.The main bands observed in all MSBs are presented in Table1.MSB elemental analysis data presented in Table2show a modification in the carbon and hydrogen composition of MSB1and a larger proportion of nitrogen as the number of amine functions in the used polyamine increases.3.3.Study of adsorption of Cu2+,Cd2+and Pb2+on MSBs2,5,and6The study of the MSB adsorption properties was accom-plished for each material and metal ion.A kinetic study and an adsorption study as a function of pH werefirst carried out.3.3.1.Effect of contact timeThe kinetic study of MSB2with Cu2+,Cd2+,and Pb2+ ions in aqueous solution is presented in Fig.5.Adsorption equilibrium was reached after20min for Cd2+ions.A time of30min was chosen for all studies of MSB2with Cd2+. The adsorption equilibrium times chosen for pH and con-centration dependent experiments are presented in Table3.Similar studies were accomplished for MSBs5and6for Cu2+,Cd2+,and Pb2+.The results are presented in Table3.3.3.2.pH EffectThe removal of metal ions from aqueous solutions by adsorption is dependent on solution pH as it affects adsor-Table1Main IR spectrum bands observed in MSBs1,5,and6MSB Main bands observed(cmÀ1)11740,172651745,1650,1635,1575,1423,1060 61738,1651,1635,1560,1400,1159,1060 Table2Elemental analysis of MSBs1,2,5,and6C(%)H(%)N(%) Sugarcane bagasse43.98 6.020.13MSB145.41 5.620.10MSB238.04 5.140.01MSB544.01 6.51 2.21MSB646.88 6.65 3.431294O.Karnitz Jr.et al./Bioresource Technology98(2007)1291–1297bent surface charge,the degree of ionization,and the species of adsorbates.The study of adsorption of Cd 2+,Cd 2+,and Pb 2+on MSB 2as a function of pH was accom-plished with the reaction times given in Table 3;the results are presented in Fig.6.The adsorption of the three metal ions increases with the increase in pH.Maximum removal of Cd 2+was observed above pH 6and in the case of Pb 2+and Cu 2,above pH 5and 5.5.Similar studies were accomplished for MSBs 5and 6and Cu 2+,Cd 2+and Pb 2+with similar results,as shown in Table 4.3.3.3.Adsorption isothermsThe Langmuir (Ho et al.,2005)(Eq.(1))and Freundlich (Eq.(2))isotherms were evaluated by adsorption experi-ments as a function of the initial metal ion concentrations in aqueous solution under equilibrium time and pH condi-tions given in Tables 3and 4.The results of each material and metal ion are presented in Fig.7(Langmuir)and Fig.8(Freundlich)and Table 5.c q ¼1Q max Âb þc Q maxð1Þln q ¼ln k þ1nln cð2ÞTable 3Adsorption equilibrium times of MSBs 2,5and 6MSB Equilibrium time (min)Cu 2+Cd 2+Pb 2+230304054040506404050Table 4pH of largest adsorption of MSBs 2,5and 6MSB pH of largest adsorption Cu 2+Cd 2+Pb 2+2 5.5–6.0 6.5–7.5 5.0–6.05 5.5–6.0 6.5–7.5 5.0–6.065.5–6.06.5–7.55.0–6.0O.Karnitz Jr.et al./Bioresource Technology 98(2007)1291–12971295where q(mg/g)is the concentration of adsorbed metal ions per gram of adsorbent,c(mg/L)is the concentration of metal ion in aqueous solution at equilibrium,Q max and b are the Langmuir equation parameters and k and n are the Freundlich equation parameters.High correlation coefficients of linearized Langmuir and Freundlich equations indicate that these models can explain metal ion adsorption by the materials satisfactorily. Therefore,both models explained metal ion adsorption by MSBs2,5,and6as can be observed in Table5,with the exception of the Freundlich model for Pb2+adsorption by MSB2.The Langmuir isotherm parameter Q max indicates the maximum adsorption capacity of the material,in other words,the adsorption of metal ions at high concentrations. It can be observed in Table5that MSB5presents the larg-est Cu2+adsorption capacity while MSB6adsorbs Cd2+ and Pb2+the ngmuir parameter b indicates the bond energy of the complexation reaction of the material with the metal ion.It can be observed that MSB2presents the largest bond energy for Cu2+and Cd2+,while three materials do not differ significantly for Pb2.The Freundlich isotherm parameter k indicates the adsorption capacity when the concentration of the metal ion in equilibrium is unitary,in our case1mg/L.This parameter is useful in the evaluation of the adsorption capacity of metal ions in dilute solutions,a case closer to the characteristics of industrial effluents.The values of k of MSB2and5are much similar for Cu2+and Cd2+ and much higher than that for MSB6.This shows the superiority of both materials in the adsorption of these metal ions in low concentrations.MSB5has a higher k value for Pb2+when compared to those of the other materials.These results were compared with those of Vaughan et al.(2001)for a commercial macroreticular chelating resin with thiol functional groups,Duolite GT-73.The Q max of Duolite GT-73for Cu2+,Cd2+,and Pb2+were 62mg/g,106mg/g,and122mg/g,respectively.Duolite GT-73exhibited Q max lower than those of MSBs(Table5).4.ConclusionsThrough a fast,effective,and cheap methodology,it was possible to devise a strategy to introduce chelating func-tions(carboxylic acid and amine)to sugarcane bagasse. Modified sugarcane bagasses presented a good adsorption capacity for Cu2+,Cd2+,and Pb2+ions with maximum adsorption capacity observed for MSB6.It has been dem-onstrated that metal ion adsorption efficiency is propor-tional to the number of amine functions introduced into the material.MSB2,which contained only carboxylate functions,showed an efficiency similar to that of MSB5, a material of much more complex synthesis. AcknowledgementsWe thank FAPEMIG forfinancial support,CAPES and UFOP.Table5The Langmuir and Freundlich parameters for Cu2+,Cd2+and Pb2+ adsorptionMetalion MSB Langmuir FreundlichQ max (mg/g)b(L/mg)r2k(mg/g)n r2Cu2+21140.431191.623.90.919351390.1730.999898.315.80.906161330.0140.992722.8 3.640.9635Cd2+21960.1030.993459.4 4.160.977351640.0680.995762.8 5.490.983463130.0040.9528 5.15 1.630.9856Pb2+21890.1100.994566.0 4.660.757951890.1250.999914724.510.98163130.1210.9994121 5.210.8771296O.Karnitz Jr.et al./Bioresource Technology98(2007)1291–1297ReferencesAcemiog˘lu,B.,Alma,M.H.,2001.Equilibrium studies on adsorption of Cu(II)from aqueous solution onto cellulose.Journal of Colloid and Interface Science243,81–83.Ali,A.A.,Bishtawi,R.,1997.Removal of lead and nickel ions using zeolite tuff.Journal of Chemical Technology and Biotechnology69, 27–34.Baird,C.,1995.Environmental Chemistry.W.H.Freeman and Company, New York.Bianchi,A.,Micheloni,M.,Paoletti,P.,1991.Thermodynamic aspects of the polyazacycloalkane complexes with cations and anions.Coordi-nation Chemistry Reviews110,17–113.Caraschi,J.C.,Campana,S.P.,Curvelo, A.A.S.,1996.Preparac¸a˜o e Caracterizac¸a˜o de Polpas Obtidas a Partir de Bagac¸o de Cana de Ac¸u´car.Polı´meros:Cieˆncia e Tecnologia3,24–29.Gellerested,F.,Gatenholm,P.,1999.Surface properties of lignocellulosic fibers bearing carboxylic groups.Cellulose6,103–121.Gurnani,V.,Singh,A.K.,Venkataramani,B.,2003.2,3-Dihydroxypyri-dine-loaded cellulose:a new macromolecular chelator for metal enrichment prior to their determination by atomic absorption spectrometry.Analytical and Bioanalytical Chemistry377,1079–1086. Ho,Y.S.,Chiu,W.T.,Wang,C.C.,2005.Regression analysis for the sorption isotherms of basic dyes on sugarcane dust.Bioresource Technology96,1285–1291.Kelter,P.B.,Grundman,J.,Hage,D.S.,Carr,J.D.,Castro-Acun˜a,C.M., 1997.A discussion of water pollution in the United States and Mexico;with High School Laboratory Activities for the analysis of lead, atrazine,and nitrate.Journal of Chemical Education74,1413–1421. Krishnan,K.A.,Anirudhan,T.S.,2002.Removal of mercury(II)from aqueous solutions and chlor-alkali industry effluent by steam activated and sulphurised activated carbons prepared from bagasse pith:kinetics and equilibrium studies.Journal of Hazardous Materials92,161–183. Martell, A.E.,Hancock,R.D.,1996.Metal complexes in aqueous solutions.Plenum,New York.Navarro,R.R.,Sumi,K.,Fujii,N.,Matsumura,M.,1996.Mercury removal from wastewater using porous cellulose carrier modified with polyethyleneimine.Water Research30,2488–2494.Orlando,U.S.,Baes,A.U.,Nishijima,W.,Okada,M.,2002.Preparation of chelating agents from sugarcane bagasse by microwave radiation as an alternative ecologically benign procedure.Green Chemistry4,555–557.Panday,K.K.,Gur,P.,Singh,V.N.,1985.Copper(II)removal from aqueous solutions byfly ash.Water Research19,869–873. Vaughan,T.,Seo,C.W.,Marshall,W.E.,2001.Removal of selected metal ions from aqueous solution using modified corncobs.Bioresource Technology78,133–139.Xiao,B.,Sun,X.F.,Sun,R.,2001.The chemical modification of lignins with succinic anhydride in aqueous systems.Polymer Degradation and Stability71,223–231.O.Karnitz Jr.et al./Bioresource Technology98(2007)1291–12971297。

2024届上海市徐汇区高三上学期一模英语试题(含听力）(3)一、听力选择题1. What does the man usually do in his spare time?A．Play chess with his grandfather.B．Play video games.C．Do some exercise.2. What are the speakers talking about?A．The man’s weekend plans.B．The man’s school life.C．The man’s friends.3.A．Happy.B．Angry.C．Relaxed.D．Confused.4. What’s the relationship between the speakers?A．Teacher and student.B．Repairman and customer.C．Classmates.5. Which flight will the man reserve?A．At 16:45.B．At 18:00.C．At 18:45.二、听力选择题6. 听下面一段较长对话，回答以下小题。

1. What has the man found?A．An old door.B．A secret dinner.C．An interesting wall.2. What’s the probable relationship between the two speakers?A．Boss and secretary.B．Father and daughter.C．Husband and wife.3. Where are the speakers?A．In a shop.B．In a house.C．In a castle.7. 听下面一段较长对话，回答以下小题。

1. Where are the speakers?A．In a restaurant.B．In a bookstore.C．In a supermarket.2. What does the man have to do now?A．Wait for his turn.B．Sign his name.C．Call his friend.8. 听下面一段较长对话，回答以下小题。

一株嗜酸氧化亚铁硫杆菌的筛选及生长条件研究吕早生;袁向利;李凌凌【摘要】从湖北某矿的酸性矿坑水中取样,在9K培养基中分离得到一株细茵C1,对该菌株进行了形态、生理生化特性及16S rRNA序列分析.结果显示该菌为革兰氏阴性菌,短杆状,经16S rRNA鉴定为嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans);生理生化鉴定结果表明其可以利用单质硫和亚铁生长,不能利用硫代硫酸钠生长.以Fe2+的氧化率为指标,研究了初始pH值、温度、接种量对C1菌生长的影响.结果表明,其最适初始pH值为2.0、温度为30℃、接种量为10%.考察了不同浸矿方法对C1菌浸磷率的影响,结果显示,经过24 d的生物浸出,普通浸矿法的浸磷率达到58.87%,比批浸矿法高出9.6%.【期刊名称】《化学与生物工程》【年(卷),期】2010(027)011【总页数】4页(P51-54)【关键词】嗜酸氧化亚铁硫杆菌;9K培养基;16S rRNA鉴定;浸磷率【作者】吕早生;袁向利;李凌凌【作者单位】武汉科技大学化学工程与技术学院,湖北,武汉,430081;武汉科技大学化学工程与技术学院,湖北,武汉,430081;武汉科技大学化学工程与技术学院,湖北,武汉,430081【正文语种】中文【中图分类】Q935;TF18嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans，简称At·f菌)为好氧化能自养微生物，以空气中的CO2为碳源，靠氧化基质中的Fe2+为Fe3+和无机硫为硫酸根而获得能量。

这一特性使其在细菌冶金、酸性废水处理、烟气脱硫和煤炭脱硫等领域具有潜在的应用价值[1]。

At·f菌可利用黄铁矿等矿物中的S、Fe，从而使矿粉分解，释放出包裹在其中的贵重金属，因此受到人们的普遍重视。

已知硫杆菌对磷矿的浸出有一定的效果，但浸出率偏低[2，3]。

作者分离出了一株氧化亚铁硫杆菌C1，对其生长条件进行了探索，经初步浸矿实验发现，该菌可以有效脱去矿石中的磷。

煤矸石煅烧实验研究李宏星【摘要】This paper discusses the three major factors affecting coal gangue calcined whitening and structure changes before and aftercalcination,points out that the calcination process selection is the ket section,but the factors is associated,mutual penetration,should not be ignored.%论述了影响煤矸石煅烧增白的三大因素及煅烧前后的结构变化，指出煅烧工艺选择是关键，但各因素又是相关连、互相渗透的，都不应忽视。

【期刊名称】《煤》【年(卷),期】2014(000)009【总页数】4页(P12-14,17)【关键词】煤矸石;煅烧;增白【作者】李宏星【作者单位】山西兴新安全生产技术服务中心，山西太原 030006【正文语种】中文【中图分类】TD849=.5煤矸石是在成煤过程中与煤层伴生的一种含碳量较低、比煤坚硬的黑灰色岩石[1]。

煤矸石中包含有多种矿物:高岭石、石英、蒙脱石、绿泥石等，其中高岭石为主要矿物，所以煤矸石通常被叫做煤系高岭岩[2]。

资料表明[3－7]，煅烧是提高煤矸石白度的有效方法。

同时，煅烧高岭土同普通高岭土相比，具有更好的化学稳定性、电绝缘性和油吸收性，并且其耐火度提高，比表面增大，比重减少。

因此，煅烧高岭土已在化工、冶金及特种工业部门得到了应用。

1 试验样品、设备与方法实验样品:样品取自大同煤矿集团塔山矿区手选煤矸石，煤矸石样品中化学成分稳定，SiO2和Al2O3的含量较高，Fe和Ti的含量不同样品之间差别较大，P、Ca、K等元素在样品中的含量较低，微量元素种类多，含量低;煤矸石中主要矿物是高岭石，还含有少量的石英。

生态毒理学报Asian Journal of Ecotoxicology第18卷第5期2023年10月V ol.18,No.5Oct.2023㊀㊀第一作者:赵子昂(1994 ),女,博士研究生,研究方向为生物资源保护与生态修复,E -mail:************************㊀㊀*通信作者(Corresponding author ),E -mail:*************************DOI:10.7524/AJE.1673-5897.20230519001赵子昂,冯永亮,王明丽,等.青岛某燃煤电厂排污口邻近海域表层沉积物重金属生态风险评价[J].生态毒理学报,2023,18(5):143-155Zhao Z A,Feng Y L,Wang M L,et al.Ecological risk assessment of heavy metals in surface sediment near a coal -fired power plant sewage outlet in Qingdao [J].Asian Journal of Ecotoxicology,2023,18(5):143-155(in Chinese)青岛某燃煤电厂排污口邻近海域表层沉积物重金属生态风险评价赵子昂1,冯永亮2,*,王明丽3,汝少国11.中国海洋大学海洋生命学院,青岛2660032.唐山学院基础教学部,唐山0630003.山东省青岛生态环境监测中心,青岛266003收稿日期:2023-05-19㊀㊀录用日期:2023-07-01摘要:沿海地区燃煤发电厂海水烟气脱硫系统长期㊁大量排放含有重金属的脱硫海水,可能会对排污口附近海域生态系统造成危害,然而目前关于这方面的研究尚少㊂本研究连续3年跟踪监测了该排污口附近海域表层沉积物中重金属As ㊁Cd ㊁Cr ㊁Cu ㊁Hg ㊁Pb 和Zn 的含量,其平均浓度分别为3.54㊁0.36㊁26.22㊁18.04㊁0.04㊁24.37和47.21mg ㊃kg -1㊂为降低传统沉积物重金属风险评价过程中的不确定性,分别采用Monte Carlo 模拟与沉积物质量基准(SQGs)和潜在生态风险指数(PERI)相结合的概率方法对其生态危害进行了评价㊂SQGs 结果显示,4次监测Cu ㊁Pb 和Cd 分别以50%㊁65%和80%的概率处于低风险,其他4种重金属以90%以上的概率处于低风险㊂PERI 结果显示,4次监测Hg 分别以34.41%㊁79.72%㊁60.39%和85.91%的概率处于中等风险,其他6种重金属的潜在生态危害均以100%的概率为轻微程度,7种重金属的综合生态危害以90%以上的概率为轻微程度㊂总体来讲,4次监测沉积物中重金属污染程度均为轻微,表明燃煤电厂脱硫海水的长期排放并未造成排污口附近海域表层沉积物重金属的污染㊂同时,本文结果表明采用Monte Carlo 模拟法与传统污染指数法相结合的概率方法能够更好地表征重金属的生态危害,为工业污染水域风险缓解提供更加详细的决策支持㊂关键词:重金属;沉积物;风险评价;燃煤电厂;Monte Carlo 模拟文章编号:1673-5897(2023)5-143-13㊀㊀中图分类号:X171.5㊀㊀文献标识码:AEcological Risk Assessment of Heavy Metals in Surface Sediment near A Coal-fired Power Plant Sewage Outlet in QingdaoZhao Ziang 1,Feng Yongliang 2,*,Wang Mingli 3,Ru Shaoguo 11.Marine Life Science College,Ocean University of China,Qingdao 266003,China2.Foundation Department,Tangshan University,Tangshan 063000,China3.Qingdao Eco -Environmental Monitoring Center of Shandong Province,Qingdao 266003,ChinaReceived 19May 2023㊀㊀accepted 1July 2023Abstract :Large amounts of waste consisting of heavy metal -containing seawater are discharged from coal -fired power plants into adjacent seas daily,which is harmful to the ecosystem of the sea near the outfall.However,very144㊀生态毒理学报第18卷few studies have been carried out on the ecological risk of these heavy metals.This study conducted a three-year continuous monitoring to the average concentrations of heavy metals in the surface sediments of the sea located near the outfall of a coal-fired power plant in Qingdao.The average concentrations of As,Cd,Cr,Cu,Hg,Pb and Zn were3.54,0.36,26.22,18.04,0.04,24.37and47.21mg㊃kg-1,respectively.In order to reduce the uncertainties in the traditional risk assessment of heavy metals in surface sediment,this study combined Monte Carlo simulations with sediment quality benchmarks(SQGs)and potential ecological risk index(PERI),respectively,to conduct the ecological risk assessment.The results of SQGs showed that,during the four sampling times,risk degrees of Cu,Pb and Cd were low with50%,65%and80%probability,respectively;As,Cr,Hg,and Zn were also at the low risk degree with more than90%probability.The PERI results showed that,during the four sampling times,the risk de-gree of Hg was moderate with34.41%,79.72%,60.39%and85.91%probability,respectively;the potential eco-logical risk degree of the other six heavy metals were low with100%probability.The combined ecological risk of these seven heavy metals was at the low degree with more than90%probability.In general,the heavy metal con-tamination degree of sediment in the four monitoring times was low,indicating that the long-term discharge of des-ulfurized seawater from coal-fired power plants did not cause heavy metal contamination in the surface sediments near the outfall.Meanwhile,the results of this study revolved that the probabilistic approach combining Monte Carlo simulation and traditional pollution index method can better characterize the ecological risk of heavy metals and provide a detailed decision support for the risk mitigation of industrially polluted waters. Keywords:heavy metals;sediments;ecological risk assessment;coal-fired power plant;Monte Carlo simulation㊀㊀近年来,沿海地区建立了越来越多的配有烟气海水脱硫系统(SFGD)的燃煤发电厂[1]㊂这些电厂利用海水弱碱性吸收烟气中SO2的同时,也会将部分重金属洗脱一起携带入海[2],从而导致附近海域重金属含量增加[3-6]㊂重金属由于具有生物毒性强㊁难生物降解以及易在生物体内累积等性质,可对海洋生物造成严重威胁,被认为是海洋环境的重要污染物[7-8]㊂例如,Zn抑制黑海胆(Arbacia lixula)生长发育的3d-EC50为21μg㊃L-1[9],导致大凤螺(Lobatusgigas)幼虫死亡的4d-LC50为8.9μg㊃L-1[10];Cu的暴露浓度为1μg㊃L-1时就会对微藻产生毒性作用[11],18μg㊃L-1时即可造成紫贻贝(Mytilus edulis) DNA损伤[12]㊂而郭娟等[13]指出脱硫海水排水口附近海域中Zn和Cu的检测范围分别为8.63~123.39μg㊃L-1和19.24~72.23μg㊃L-1㊂因此,有必要开展脱硫海水长期排放对排污口附近海域的生态风险评价工作㊂目前燃煤电厂脱硫海水重金属的研究主要集中于具有挥发性质的Hg在烟气和水环境介质中的迁移转化[14-17],而对于其他重金属,如As㊁Cd㊁Cr㊁Cu㊁Pb和Zn的长期排放对排污口附近海域的影响的研究尚未见报道㊂水环境中的重金属,由于吸附㊁水解和沉淀的共同作用,只有一小部分的自由金属离子溶解在水中,大部分都沉积于沉积物中[18]㊂因此,对重金属的生态风险评价主要集中在沉积物上㊂目前,已有多种污染指数法可用于沉积物中重金属的风险评价[19]㊂其中,沉积物质量基准(SQGs)[20-21]㊁潜在生态危害指数(potential ecological risk index,PERI)[22-23]㊁地累积指数(Igeo)[1,24]㊁富累积因子(EF)[25]㊁污染严重指数(CSI)[26]等均是较为常用的方法㊂Ranjbar Jafarabadi 等[8]采用SQGs㊁PERI㊁CSI等10种方法评价了波斯湾10个珊瑚岛沿海表层沉积物中13种重金属的生态风险,其中基于EF和PERI的结果显示V㊁Ni㊁Hg 和Cd为中等污染水平,需要引起关注㊂然而,上述污染指数法通常仅使用(或联合使用)数据的平均值㊁保守值(90%或95%分位数)和最大值来获得风险的一个平均或保守的估计[25,27]㊂这种将监测数据压缩为一个单点值的方法会导致生态风险评价中信息的丢失,产生不确定性,从而造成对风险的高估或者低估㊂因此,美国国家科学院和环境保护局推荐使用Monte Carlo模拟方法来量化风险评价中的可变性和不确定性[28-29]㊂这种随机模拟技术通过产生大量的符合一定规律的随机数,将其带入到有效的风险评价模型,进而得到风险的概率分布,为决策者提供更多的信息㊂燃煤电厂附近海域重金属浓度一般是通过浓度增量(根据电厂及SFGD的运行参数)叠加环境背景值或对电厂运行后的短期检测获得的[30]㊂然而,由第5期赵子昂等:青岛某燃煤电厂排污口邻近海域表层沉积物重金属生态风险评价145㊀于估计值或短期检测值的不确定因素较多,导致以其为基础的风险评价结果具有较大的不确定性㊂因此,本研究连续3年跟踪监测了青岛某燃煤电厂排污口附近海域沉积物中As㊁Cd㊁Cr㊁Cu㊁Hg㊁Pb和Zn 的浓度㊂基于重金属的长期暴露数据,采用Monte Carlo模拟技术与SQGs和PERI相结合的概率方法评价了排污口附近海域沉积物中重金属的生态风险㊂本研究能够为燃煤电厂排口附近海域的污染控制和生态风险减缓提供更多的科学依据㊂1㊀材料与方法(Materials and methods)1.1㊀沉积物样品的采集在青岛胶州湾某燃煤电厂排污口附近海域共设置了12个站位(图1)㊂利用采泥器分别于2012年12月26日和2013年6月21日的低潮期采集表层2cm处的沉积物混合样,去除上覆水后,装入密封的聚乙烯袋中带回实验室㊂样品运回实验室后,晾干,研磨至完全通过160目(96μm)的尼龙筛,然后存储到预先准备好的干净样品袋中以待进一步分析㊂此外,本研究还引用了王云鹏等[31]于2011年12月23日和2012年6月5日对该排污口附近表层沉积物的重金属监测数据㊂其站位设置与采样方法均与本研究相同㊂2011年12月23日未在4#站位采集到沉积物样本,2013年6月21日未在1#和4#站位采集到沉积物样本㊂沉积物样品采集回实验室后,置于冷冻干燥机中进行冻干,并研磨过160目筛,之后密封冷藏保存㊂1.2㊀重金属分析与质量控制取沉积物样品0.04g置于Teflon容器中,加入0.8mL HNO3(VʒV=1ʒ1)和0.8mL HF,再加入HClO4(VʒV=1ʒ3)后,密封超声震荡60s,然后在100ħ下恒温加热蒸干㊂再加入0.8mL HNO3(VʒV=1ʒ1),在100ħ下恒温加热蒸干㊂之后加入0.8mL的HF和HClO4,密封置于高压釜中,在170ħ烘箱内加热㊂样品蒸干之后再加入4mL4mol㊃L-1的HNO3,在170ħ烘箱内加热4h㊂最后用3%(V ʒV)HNO3稀释并移至50mL的容量瓶中,加入Rh-Re内标液,以1%(VʒV)HNO3至稀释至50mL 以备分析使用㊂重金属分析采用美国安捷伦公司生产的等离体质谱仪ICP-MS(Agilent7500CX),标准物质为安捷伦公司多元素混合标准溶液(批号:5183-4688)㊂通过该方法,金属元素As㊁Cd㊁Cr㊁Cu㊁Hg㊁Pb和Zn的图1㊀调查站位设置Fig.1㊀Map of sampling stations near the outlet of the coal-fired power plant146㊀生态毒理学报第18卷最低检出限分别为0.2㊁0.02㊁1㊁0.2㊁0.01㊁0.5和2mg ㊃kg-1;所有金属样品的回收率均在90%~110%范围内,重复样品的相对标准差均<10%㊂1.3㊀沉积物质量基准法(SQGs)SQGs方法是基于北美沉积物生物效应数据库构建的多阈值型基准,广泛用于海洋沉积物中污染物的风险评价[20,32-33]㊂Long等[20]将导致10%和50%有害生物效应的污染物浓度分别称为效应范围低值(effect range low,ERL)和效应范围中值(effect range median,ERM),随后MacDonald等[21]又对该阈值做了修改,给出了一对更为严格的阈值:临界效应水平(threshold effect level,TEL)和可能发生效应水平(probable effect level,PEL)㊂当污染物的环境浓度EEC(estimated environmental concentration)<ERL或TEL时,将不会导致有害生物效应,为低风险;当EEC>ERM或PEL时,将导致有害生物效应,为高风险;当EEC值位于二者之间时,认为污染物导致毒性效应的概率和不导致毒性效应的概率相当,为中等风险㊂每种金属的具体基准值见表1㊂1.4㊀潜在生态危害指数法(PERI)基于水生生态系统的敏感性依赖于其生产力的假设,Hakanson[22]提出了PERI方法㊂该方法结合监测浓度与生态效应㊁环境效应和毒性的关系,对沉积物中重金属的污染程度进行评估㊂其具体计算公式如下:RI=ðE ir(1)E ir=T irC if(2)C if=C i/C ir(3)式中:RI为多种金属的综合潜在生态危害指数,E ir 为金属i的潜在生态危害指数,T ir为金属i的毒性响应系数,C if为金属i的污染系数,C i为重金属i的实测浓度,C ir为金属i的沉积物背景值㊂各类重金属的背景值是该海域未受到影响时的测量值,本研究参考王云鹏等[31]所给出的胶州湾沉积物中重金属背景值和毒性响应系数(表2)㊂基于上述参考值,重金属潜在生态危害指数对应的危害程度分级标准见表3㊂表1㊀7种重金属的不同类型海洋沉积物质量基准值Table1㊀Different types of marine sediment quality guideline values for the seven heavy metals(mg㊃kg-1)重金属Heavy metalsTEL PEL ERL ERM 砷As7.2441.68.270镉Cd0.68 4.21 1.29.6铬Cr52.316081370铜Cu18.710834270汞Hg0.130.70.150.71铅Pb30.211246.7218锌Zn124271150410注:数据引自文献[21];TEL指临界效应水平;PEL指可能发生效应水平;ERL为效应范围低值;ERM为效应范围中值㊂Note:The data come from Reference[21];TEL means threshold effect level;PEL means probable effect level;ERL means effect range low;ERM means effect range median.表2㊀胶州湾沉积物中重金属浓度背景参考值及毒性响应系数Table2㊀The background values and toxic-response factors of heavy metals in sediments of Jiaozhou Bay砷As 镉Cd铬Cr铜Cu汞Hg铅Pb锌ZnC ir/(mg㊃kg-1)7.750.6658.1660.340.02426.2678.28T ir1030254051注:C i r为金属的沉积物背景值;T i r为金属的毒性响应系数㊂Note:C i r means background values of heavy metals in sediments;T i r means toxic response factor for heavy metals.第5期赵子昂等:青岛某燃煤电厂排污口邻近海域表层沉积物重金属生态风险评价147㊀1.5㊀Monte Carlo模拟本研究采用Monte Carlo模拟技术与传统的SQGs和PERI相结合的概率方法评价表层沉积物中重金属的生态风险㊂Monte Carlo模拟技术是将模型或者方法中需要输入的关键变量(如污染物的浓度)视为符合某种概率分布的随机变量,通过重复抽样,带入到模型或者方法中得到输出结果的概率分布[34]㊂本研究采用log-normal㊁log-logistic和Weibull分布分别对每种重金属的监测数据进行分布拟合,根据Kolmogorov-Smirnov检验选择最优模型:P值越接近于1,拟合效果越好[35]㊂总体上,log-logistic的拟合效果要优于其他2种分布㊂基于log-logistic,运用软件Matlab v.9.3(MathWorks Inc.,Natick,Massa-chusetts)对每个数据集进行10万次的随机抽样㊂然后再结合SQGs和PERI法,得到超过各个SQGs标准值的概率以及E ir和RI的概率分布,进而得到重金属所处各个风险水平的概率等更为详细的信息㊂2㊀结果(Results)2.1㊀表层沉积物中重金属含量4次监测排污口附近海域表层沉积物中As㊁Cd㊁Cr㊁Cu㊁Hg㊁Pb和Zn的浓度范围分别为1.54~ 7.33㊁0.08~0.72㊁12.16~54.04㊁5.08~33.10㊁0.02~ 0.08㊁8.37~35.91和14.58~85.01mg㊃kg-1,平均浓度分别为3.54㊁0.36㊁26.22㊁18.04㊁0.04㊁24.37和47.21mg㊃kg-1㊂7种重金属4次监测的平均浓度均符合中国海洋沉积物质量标准(GB18668 2002)的一类标准值㊂各个监测时间的详细结果见表4㊂排污口附近下游区域(2#~11#站位)沉积物中重金属的平均浓度大体上都高于排水口上游的1#站位和胶州湾对照点12#站位㊂如2012年12月,2#~11#站位As㊁Cd㊁Cr㊁Cu㊁Pb和Zn的平均浓度分别为4.25㊁0.34㊁37.51㊁22.03㊁26.90和57.61mg㊃kg-1,高于1#站位的2.86㊁0.10㊁17.03㊁15.29㊁23.75和40.31mg㊃kg-1,高于12#站位的3.81㊁0.08㊁23.34㊁8.58㊁16.01和表3㊀沉积物中重金属潜在生态危害指数对应的危害程度分级标准Table3㊀Criteria for degrees of the ecological risk of heavy metal in sedimentsE ir范围Range of E i r单个因子危害程度Risk degree of individual factorRI范围Range of RI多个因子综合危害程度Risk degree of multiple factorsE ir<40轻微Low RI<150轻微Low 40ɤE i r<80中等Moderate150ɤRI<300中等Moderate80ɤE i r<160强Considerable300ɤRI<600强Considerable160ɤE i r<320很强High RIȡ600很强HighE ir>320极强Extreme注:E i r为金属的潜在生态危害指数;RI为多种金属的综合潜在生态危害指数㊂Note:E i r means potential ecological risk index for a certain heavy metal;RI means the potential ecological risk index of heavy metals.表4㊀电厂排污口附近海域表层沉积物重金属含量Table4㊀Statistics of concentrations of the heavy metals in the marine surfacesediment near the outlet of the power plant(mg㊃kg-1)重金属Heavy metal2011.12a2012.06a2012.122013.06范围Range平均值Mean标准差SD范围Range平均值Mean标准差SD范围Range平均值Mean标准差SD范围Range平均值Mean标准差SD砷As 3.23~7.33 4.99 1.50 2.04~3.28 2.710.36 3.33~5.04 4.210.54 1.54~2.99 2.250.40镉Cd0.11~0.550.260.120.25~0.720.520.150.08~0.680.310.190.09~0.610.320.17铬Cr14.75~42.7824.417.0715.76~38.4123.25 6.4123.34~54.0436.228.7212.16~45.7820.3010.02铜Cu 5.35~31.4018.93 6.70 6.43~18.2513.87 3.928.58~33.1020.818.61 5.08~25.7118.71 6.45汞Hg0.03~0.050.040.0080.03~0.060.0450.010.02~0.050.030.0080.04~0.080.0540.013铅Pb8.37~25.0917.98 4.7717.46~35.9125.76 5.5315.03~35.6425.91 6.7013.48~33.7127.51 6.28锌Zn24.13~85.0155.1515.8419.84~52.7635.849.7741.66~83.4956.9613.7214.58~63.8141.0317.79注:a表示引自文献[31];SD为标准差㊂Note:a represents that the data come from Reference[31];SD means standard deviation.148㊀生态毒理学报第18卷50.53mg㊃kg-1,Hg的浓度变化不明显㊂2.2㊀基于Monte Carlo模拟的SQGs评价结果由Monte Carlo模拟与SQGs相结合,可以得到实际监测数据高于各个SQGs标准值的概率㊂表5列出了7种重金属超越4种SQGs标准值的具体概率㊂由表5可知,如果以ERL/ERM这对较为宽松的标准来看,4次监测7种重金属均以90%以上的概率处于低风险,因此以下分析均依据TEL/PEL这对较为严格的标准进行㊂从不同监测时间来看,2011年12月Cu以49.91%的概率为中等风险,49.99%的概率为低风险,其他6种重金属均以90%以上的概率为低风险㊂2012年6月Cd㊁Cu和Pb处于低风险的概率分别为81.26%㊁84.60%和82.94%,处于中等风险的概率分别为18.74%㊁15.40%和17.06%,其他4种重金属均以99%以上的概率处于低风险㊂2012年12月Cu和Pb处于低风险的概率分别为46.58%和74.39%,处于中等风险的概率分别为53.32%和25.60%,其他5种重金属均以90%以上的概率处于低风险㊂2013年6月,Cu和Pb处于低风险的概率分别为49.24%和64.22%,处于中等风险的概率分别为50.72%和35.77%,其他5种重金属均以90%以上的概率处于低风险㊂从不同重金属的角度来看,4次监测As㊁Cr㊁Hg表5㊀7种重金属超越ERL和ERM的概率Table5㊀Probabilities of exceeding ERL and ERM for the seven heavy metals重金属Heavy metal时间Sampling dateTEL PEL ERL ERM砷As 2011.127.77E-020 3.89E-020 2012.060000 2012.12 6.00E-040 1.20E-040 2013.060000镉Cd 2011.128.43E-030 5.70E-040 2012.06 1.87E-0109.01E-030 2012.127.52E-02 4.10E-04 1.69E-020 2013.06 6.72E-02 2.60E-04 1.28E-020铬Cr 2011.128.10E-040 2.07E-050 2012.06 1.63E-030 5.42E-050 2012.12 5.40E-020 2.00E-030 2013.06 5.24E-03 2.66E-05 5.80E-040铜Cu 2011.12 5.00E-01 3.00E-04 5.45E-020 2012.06 1.54E-01 3.00E-05 6.10E-030 2012.12 5.34E-01 1.00E-039.72E-02 1.52E-05 2013.06 5.08E-01 4.00E-04 6.842E-02 2.00E-05汞Hg 2011.12 1.20E-040 5.74E-050 2012.06 3.90E-040 1.20E-040 2012.12 6.00E-050 1.97E-050 2013.06 5.00E-040 1.40E-040铅Pb 2011.12 3.15E-02 1.00E-05 1.88E-030 2012.06 1.71E-010 5.35E-030 2012.12 2.56E-01 3.71E-05 1.87E-020 2013.06 3.58E-01 3.21E-05 2.00E-020锌Zn 2011.12 5.31E-030 1.56E-030 2012.06 3.30E-0409.25E-050 2012.12 2.63E-03 1.00E-05 6.40E-040 2013.06 1.79E-02 1.21E-039.26E-03 3.30E-04注:代号意义同表1㊂Note:The meanings of symbols are the same as those in Table1.第5期赵子昂等:青岛某燃煤电厂排污口邻近海域表层沉积物重金属生态风险评价149㊀和Zn 均以90%以上的概率处于低风险㊂Cd 除2012年6月以18.74%的概率处于中等风险外,其他3次均以90%以上的概率处于低风险㊂Cu 4次监测处于中等风险的概率分别为49.91%㊁15.40%㊁53.32%和50.72%㊂Pb 4次监测处于中等风险的概率分别为3.15%㊁17.06%㊁25.60%和35.77%㊂虽然2011年12月Cu 的平均浓度为18.93mg ㊃kg -1,略大于其TEL(18.7mg ㊃kg -1),处于中等风险,但其仍有49.99%的概率处于低风险㊂2012年12月Cu 的平均浓度为20.81mg ㊃kg -1,为其TEL(18.7mg ㊃kg -1)的1.11倍,处于中等风险,但其仍有46.58%的概率为低风险,可见应用Monte Carlo 模拟与SQGs 相结合能够得到更加详细的结果㊂总体来讲,4次监测As ㊁Cr ㊁Hg 和Zn 均为低风险,Cd 以80%以上的概率处于低风险,Pb 以65%以上的概率处于低风险,Cu 有3次以大约50%的概率处于中等风险㊂7种重金属对脱硫排污口附近海域的污染程度较小,其大小顺序为Cu>Pb>Cd>As ʈCr ʈHg ʈZn ㊂2.3㊀基于Monte Carlo 模拟的PERI 评价结果采用Monte Carlo 模拟与PERI 相结合的评价方法,可以得到各重金属生态危害指数(E i r )的累积概率曲线(图2),以及其所处每个风险级别的概率(表6)㊂4次监测As ㊁Cr ㊁Cu ㊁Pb 和Zn 的潜在生态危害均以100%的概率为轻微程度,4次监测Cd 的潜在生态危害均以90%以上的概率为轻微程度㊂Hg 前3次监测的平均潜在生态危害为中等程度,其处于中等程度的概率分别为79.72%㊁60.39%和85.91%,2013年6月Hg 以64.68%的概率为强危害程度㊂2011年12月㊁2012年6月㊁2012年12月和2013年6月的综合生态危害指数(RI)分别为86.10㊁110.32㊁85.89和115.33,均<150(轻微程度的上限值),属于轻微危害程度㊂Monte Carlo 模拟结果显示,4次监测沉积物中重金属的综合生态危害以90%以上的概率为轻微程度(图3)㊂总体来讲,4次监测沉积物中重金属污染程度均为轻微㊂SQGs 显示Cu ㊁Cd 和Pb 污染程度相对较大㊂PERI 方法结果显示Hg 的污染程度最大,其中夏季(2012.06和2013.06)重金属的污染程度要略高于冬季(2011.12和2012.12)㊂图2　单个重金属潜在生态危害指数(E i r )的累积概率曲线Fig.2㊀Cumulative probability curves of potential ecological risk factor (E i r )for individual heavy metal150㊀生态毒理学报第18卷表6㊀基于平均值估计和概率估计的单个重金属的生态风险Table6㊀Ecological risk of each heavy metal derived from both average estimation and probabilistic estimation时间Sampling date 重金属Heavymetal平均值估计Estimation of mean valueMonte Carlo模拟估计每个风险级别的概率Probability of each risk degree estimated by Monte Carlo simulation 平均E i r值Mean value of E i r风险级别Risk degree轻微/%Low/%中等/%Moderate/%强/%Considerable/%很强/%High/%极强/%Extreme/%2011.12As 6.44Low1000000 Cd11.89Low99.690.31000 Cr0.84Low1000000 Cu 1.57Low1000000 Hg61.23Moderate 5.8979.7214.200.180.01 Pb 3.42Low1000000 Zn0.70Low10000002012.06As 3.49Low1000000 Cd23.76Low94.93 4.960.1100 Cr0.80Low1000000 Cu 1.15Low1000000 Hg75.76Moderate 1.0160.3938.260.340 Pb 4.91Low1000000 Zn0.46Low10000002012.12As 5.43Low1000000 Cd14.25Low96.09 3.290.530.070.02 Cr 1.25Low1000000 Cu 1.72Low1000000 Hg57.58Moderate7.2985.91 6.770.030 Pb 4.93Low1000000 Zn0.73Low10000002013.06As 2.91Low1000000 Cd14.41Low96.72 2.840.380.050.01 Cr0.70Low1000000 Cu 1.55Low1000000 Hg90.00High0.1534.4164.860.580 Pb 5.24Low1000000 Zn0.52Low1000000注:As㊁Cd㊁Cr㊁Cu㊁Hg㊁Pb和Zn分别指重金属砷㊁镉㊁铬㊁铜㊁汞㊁铅和锌;Low㊁Moderate和High分别表示风险级别为轻微㊁中等和很强㊂Note:As,Cd,Cr,Cu,Hg,Pb and Zn means arsenic,cadmium,chromium,copper,mercury,lead and zinc,respectively;Low,Moderate,and High indicate that risk degree is low,moderate and very high,respectively.3㊀讨论(Discussion)本研究海域表层沉积物重金属平均浓度与胶州湾以及其他受人类活动影响较大海域的对比如表7所示㊂对比分析发现,本研究4次监测表层沉积物中Cd㊁Cr㊁Cu㊁Pb和Zn的平均浓度均高于2004年5月胶州湾的平均浓度[36],表明脱硫海水的长期大量排放确实引起了附近海域沉积物中重金属的累积㊂本研究Cd㊁Hg和Pb的平均浓度高于2009年胶州湾跨海大桥附近沉积物中的平均浓度[37],但大部分重金属含量低于胶州湾东部沉积物中的含量[38]㊂类似的,李玉等[39]运用平均富集因子发现胶州湾表层沉积物中重金属主要分布在胶州湾东部李村河口㊁娄山河口以及附近海域㊂魏璟弢等[40]应用连续提取法研究了2008年11月和2010年11月青岛近海和胶州湾内沉积物的富集状况,发现Pb和Cr存在明显富集,胶州湾东部重金属污染程度最为明显㊂本研究As㊁Cd㊁Cu㊁Hg㊁Pb和Zn的浓度比五里河河口附近海域(葫芦岛锌厂排污口邻近海域)低一个数量第5期赵子昂等:青岛某燃煤电厂排污口邻近海域表层沉积物重金属生态风险评价151㊀级[41]㊂与我国高雄湾[15]㊁香港海岸带[40]㊁泉州湾[42]以及国外一些其他海湾(表7)相比,本研究沉积物中重金属含量均低于上述区域㊂总体上,该燃煤电厂排污口附近海域沉积物中重金属的浓度较低㊂图3㊀7种重金属综合潜在生态危害指数(RI )的累积概率曲线Fig.3㊀Cumulative probability curves of comprehensive potential ecological risk index (RI)of seven heavy metals㊀㊀目前燃煤电厂脱硫海水重金属的研究主要集中于具有挥发性质的Hg 在烟气和水环境介质中的迁移转化以及其不同形态在水环境中的分布特征[1]㊂Liang 等[43]研究发现燃煤电厂排污口附近海域表层沉积物中Hg 的浓度范围为0.055~0.201mg ㊃kg -1,平均值为0.126mg ㊃kg -1,为本研究Hg 浓度的3倍左右㊂本研究采用PERI 方法过程中由于选用了该地区Hg 的较低背景值0.024mg ㊃kg -1[31,44],导致其潜在生态危害指数(E i r )范围为57.58~90.00,污染程度远大于其他重金属㊂此外,PERI 方法不仅考虑了重金属的环境背景值,还考虑了其毒性系数㊂Hg 由于具有高毒性,尤其是通过生物体产生的有机汞,其毒性系数采用了所有重金属元素中最高的40㊂Li 等[35]采用地累积指数法和PERI 法对2009年7月胶州湾表层沉积物8种重金属的污染和潜在生态危害进行了评价,发现重金属总体污染程度较轻,但Hg 污染较为严重,与本研究结果一致㊂此外,由于夏季(2012.06和2013.06)Hg 的监测浓度要略高于冬季(2011.12和2012.12),进而导致夏季重金属的综合生态危害指数(RI)也略高于冬季㊂本研究4次监测重金属的RI 均<150(轻微程度的上限值),属于轻微危害程度㊂类似的,郭军辉等[38]采用潜在生态危害指数法对2009年胶州湾东岸表层沉积物重金属的生态危害进行了评价,发现Cd 对沉积物生态环境的潜在危害为中等程度,As ㊁Cr ㊁Cu ㊁Pb 和Zn 的危害程度均为轻微,多个重金属的RI 值均<150,属于轻微危害程度㊂目前大部分针对沉积物重金属生态风险评价的方法,包括SQGs 和PERI ,都采用监测数据的平均值㊁保守值(90%或95%分位数)或最大值来获得风险的一个平均或保守的估计[25-26]㊂这种将监测数据压缩为一个单点值的方法会导致生态风险评价中信息的丢失,产生不确定性,从而造成对风险的高估或者低估㊂本研究中2012年12月Cu 的平均浓度为20.81mg ㊃kg -1,为其TEL(18.7mg ㊃kg -1)的1.11倍,处于中等风险,但结合Monte Carlo 模拟发现其仍有46.58%的概率为低风险㊂类似的,Sawe 等[45]发现坦桑尼亚的瓦米河口中As ㊁Cd ㊁Cr ㊁Pb 和Zn 的浓度以99%的概率低于SQGs 的效应范围低值,风险可忽略,但Cu 却有一定的概率对该河口造成风险㊂此外,本研究2012年6月Hg 的平均E i r 值为75.76(为中等程度上限值80的0.947倍),生态危害程度为中等,但由Monte Carlo 模拟的结果可得其仍有38.26%的概率处于强危害程度㊂Qu 等[34]指出虽然香江和天池湖的平均RI 值略高于高危害程度(high risk)的上限值600(分别为其1.08倍和1.17倍),处于高危害程度,但Monte Carlo 模拟结果显示其仍有43.3%和47.1%的概率处于较高危害程度(consider -able risk)㊂Li 等[35]指出尽管莱州湾西部Hg 的平均E i r 为20.24(为轻微程度上限值40的0.51倍),但Monte Carlo 模拟显示仍有一定的概率(0.03%)处于中等危害程度㊂可见只用平均值进行评价,可能会高估或者低估重金属的真实风险㊂采用Monte Carlo 模拟与传统评价方法相结合能够有效降低风险评估的不确定性,为污染水域沉积物重金属风险缓解提供更多的决策支持㊂目前对于像燃煤电厂这样的点污染源的暴露评价主要是基于电厂建设前的模型预测研究,缺少电厂运行后的长期跟踪监测[2]㊂并且模型涉及大量的污染物特有参数(如分子量㊁蒸气压㊁吸附系数等)和环境场景参数,其结果往往具有一定的不确定性[46]㊂本研究将脱硫海水工艺运行10年后,连续3年的跟踪监测数据作为环境暴露数据能更好地表征重金属排放对排污口附近海域的长期生态风险㊂SQGs 和PERI 方法均显示4次监测沉积物中重金属污染程度为轻微,表明燃煤电厂脱硫海水的长期排放并未造成排污口附近海域表层沉积物重金属的污染㊂除152㊀生态毒理学报第18卷重金属外,脱硫海水中的其他特征性污染物pH (H+)㊁SO42-㊁温度等也可能对排污口附近海域造成不利影响[2]㊂为研究脱硫海水排放对海洋生态环境的综合影响,本研究还根据调查了排污口附近海域的生物群落结构(本研究未列出),共发现浮游植物4门93种,其中硅藻78种;浮游动物58种,其中节肢动物类和浮游幼虫类分别有27种和17种;底栖动物8门128种,其中环节动物门69种㊂依据Shan-non-Wiener多样性指数和Pielou均匀度指数[31],排污口附近海域各类群生物多样性较高,群落结构较稳定,表明脱硫海水排放未对生物群落结构和生物多样性造成明显不利影响㊂表7㊀电厂排污口附近海域与其他受影响海域中表层沉积物重金属的平均浓度比较Table7㊀Mean concentrations of heavy metals found in sediment near the outlet of the power plant compared to the reported average concentrations for other impacted coastal systems(mg㊃kg-1)地区Area 砷As镉Cd铬Cr铜Cu汞Hg铅Pb锌Zn参考文献Reference中国胶州湾Jiaozhou Bay,China 3.540.3626.2218.040.0424.3747.21本研究This study中国胶州湾Jiaozhou Bay,China11.150.05922.1411.99-10.3131.1[36]中国胶州湾Jiaozhou Bay,China-0.055-19.050.03112.751.14[37]中国胶州湾Jiaozhou Bay,China10.900.5577.4036.23-52.94161.32[38]中国五里河口Wulihe Estuary,China88.25 4.11-116.600.56104.651008.75[41]中国泉州湾Quanzhou Bay,China21.70.5982.071.40.4067.70179.6[42]中国香港近岸Hong Kong Coasts,China-0.3348.93118.680.1953.56147.73[47]中国台湾高雄港Kaohsiung Harbor,Taiwan,China-0.93154.15117.600.4655.23318.33[48]意大利那不勒斯湾Gulf of Naples,Italy2.00.572827.20.70221602[49]巴西里贝拉湾Ribeira Bay,Brazil-0.20711824.6-22.9109[50]巴西塞佩提巴湾Sepetiba Bay,Brazil- 3.226631.9-40567[50]通信作者简介:冯永亮(1987 ),男,博士,讲师,主要研究方向为生态风险评价和水质基准构建㊂参考文献(References):[1]㊀Liu X Y,Sun L M,Yuan D X,et al.Mercury distributionin seawater discharged from a coal-fired power plant e-quipped with a seawater flue gas desulfurization system[J].Environmental Science and Pollution Research Inter-national,2011,18(8):1324-1332[2]㊀Córdoba P.Status of flue gas desulphurisation(FGD)sys-tems from coal-fired power plants:Overview of the phys-ic-chemical control processes of wet limestone FGDs[J].Fuel,2015,144:274-286[3]㊀Clarke L B.The fate of trace elements during coal com-bustion and gasification:An overview[J].Fuel,1993,72(6):731-736[4]㊀Aunela-Tapola L,HatanpääE,Hoffren H,et al.A studyof trace element behaviour in two modern coal-fired pow-er plants:Ⅱ.Trace element balances in two plants e-quipped with semi-dry flue gas desulphurisation facilities[J].Fuel Processing Technology,1998,55:13-34[5]㊀Radojevi M.The use of seawater for flue gas desulphuri-。

⽔处理专业英语阅读1WaterPollutionandPollutants1 Water Pollution and PollutantsThe relationship between polluted water and disease was firmly established with the cholera epidemic of 1854 in London, England. Protection of public health, the original purpose of pollution control, continues to be the primary objective in many areas. However, preservation of water resources, protection of fishing areas, and maintenance of recreational waters are additional concerns today. Water pollution problems intensified following World War II when dramatic increases in urban density and industrialization occurred. Concern over water pollution reached a peak in the mid-seventies.Water pollution is an imprecise term that reveals nothing about either the type of polluting material or its source. The way we deal with the waste problem depends upon whether the contaminants are oxygen demanding, algae promoting, infectious, toxic, or simply unsightly. Pollution of our water resources can occur directly from sewer outfalls or industrial discharges (point sources) or indirectly from air pollution or agricultural or urban runoff (nonpoint sources).Chemically pure water is a collection of H2O molecules—nothing else. Such a substance is not found in nature—not in wild streams or lakes, not in clouds or rain, not in falling snow, nor in the polar ice caps. V ery pure water can be prepared in the laboratory but only with considerable difficulty. Water accepts and holds foreign matter.Municipal wastewater, also called sewage, is a complex mixture containing water (usually over 99 percent) together with organic and inorganic contaminants, both suspended and dissolved. The concentration of these contaminants is normally very low and is expressed in mg/L, that is, milligrams of contaminant per liter of the mixture. This is a weight-to-volume ratio used to indicate concentrations of constituents in water, wastewater, industrial wastes, and otherdilute solutions.Microorganisms.Wherever there is suitable food, sufficient moisture, and an appropriate temperature, microorganisms will thrive. Sewage provides an ideal environment for a vast array of microbes, primarily bacteria, plus some viruses and protozoa. Most of these microorganisms in wastewater are harmless and can be employed in biological processes to convert organic matter to stable end products. However, sewage may also contain pathogens from the excreta of people with infectious diseases that can be transmitted by contaminated water. Waterborne bacterial diseases such as cholera, typhoid, and tuberculosis, viral diseases such as infectious hepatitis, and the protozoan-caused dysentery, while seldom a problem now in developed countries, are still a threat where properly treated water is not available for public use. Tests for the few pathogens that might be present are difficult and time consuming, and standard practice is to test for other more plentiful organiama that are always present (in the billions) in the intestines of warm-blooded animals, including humans.Solids. The total solids (organic plus inorganic) in wastewater are, by definition, the residues after the liquid portion has been evaporated and the remainder dried to a constant weight at 103℃. Differentiation between dissolved solids and undissolved, that is, suspended, solids are accomplished by evaporating filtered and unfiltered wastewater samples. The difference in weight between the two dried samples indicates the suspended solids content. To further categorize the residues, they are held at 550℃for 15 minutes. The ash remaining is considered to represent inorganic solids and the loss of volatile matter to be a measure of the organic content Suspended solids (SS) and volatile suspended solids (VSS) are the most useful. SS and BOD (biochemical oxygen demand) are used as measures of wastewater strength and process performance. VSS can be an indicator of the organic content of raw wastes and can also providea measure of the active microbial population in biological processes.Inorganic constituents. The common inorganic constituents of wastewater include:1. Chlorides and sulphates. Normally present in water and in wastes from humans.2. Nitrogen and phosphorous . In their various forms (organic and inorganic) in wastes from humans, with additional phosphorous from detergents.3. Carbonates and bicarbonates. Normally present in water and wastes as calcium and magnesium salts.4. Toxic substances. Arsenic, cyanide, and heavy metals such as Cd, Cr, Cu, Hg, Ph, and Zn are toxic inorganics which may be found in industrial wastes.In addition to these chemical constituents, the concentration of dissolved gases, especially oxygen, and the hydrogen ion concentration expressed as pH are other parameters of interest in wastewater.Organic matter.Proteins and carbohydrate constitute 90 percent of the organic matter in domestic sewage. The sources of these biodegradable contaminants include excreta and urine from humans; food wastes from sinks; soil and dirt from bathing;washing, and laundering; plus various soaps, detergents, and other cleaning products.V arious parameters are used as a measure of the organic strength of wastewater. One method is based on the amount of organic carbon (total organic carbon, or TOC) present in the waste. TOC is determined by measuring the amount of CO2 produced when the organic carbon in the sample is oxidized by a strong oxidizer and comparing it with the amount in a standard of known TOC.Most of the other common methods are based on the amount of oxygen required to convert the oxidizable material to stable end products. Since the oxygen used is proportional to theoxidizable material present, it serves as a relative measure of wastewater strength. The two methods used most frequently to determine the oxygen requirements of wastewater are the COD and BOD tests. The COD. or chemical oxygen demand, of the wastewater is the measured amount of oxygen needed to chemically oxidize the organics present; the BOD. or biochemical oxygen demand, is the measured amount of oxygen required by acclimated microorganisms to biologically degrade the organic matter in the wastewater.BOD is the most important parameter in water pollution control. It is used as a measure of organic pollution, as a basis for estimating the oxygen needed for biological processes, and as an indicator of process performance.The amount of organic matter in water or wastewater can be measured directly (as TOC, for example), hut this doesn’ t tell us whether the organic s are biodegradable or not. To measure the amount of biodegradable organics, we use an indirect method in which we measure the amount of oxygen used by a growing microbial population to convert (oxidize) organic matter to CO2 and H2O in a closed system. The oxygen consumed. or biochemical oxygen demand (BOD). is proportional to the organic matter converted, and therefore BOD is a relative measure of the biologically degradable organic matter present in the system. Because biological oxidation continues indefinitely, the test for ultimate BOD has been arbitrarily limited to 20 days, when perhaps 95 percent or more of the oxygen requirement has been met. Even this period, however, is too long to make measurement of BOD useful, so a five-day test, BOD5, carried out at 20℃, has become standard. The rate of the BOD reaction depends on the type of waste present and the temperature and is assumed to vary directly with the amount of organic matter (organic carbon) present.单词表。

不同方法提取嗜酸氧化亚铁硫杆菌胞外聚合物的比较分析顾卫华;白建峰;卢亮;张洁娜;王景伟【摘要】从嗜酸氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans,A.f菌)中提取胞外聚合物(Extracellular Ploymeric Substances,EPS)的方法有很多,但不同方法提取的EPS成分及含量都有较大区别.通过对比NaOH法、EDTA法、超声法、离心法提取A.f菌EPS的研究,分析高效提取A.f菌EPS方法的同时,得到EPS成分及含量在不同提取方法下的变化情况.实验结果表明,对于未驯化和驯化处理的实验组,超声法提取的EPS最多,分别达到37.1 mg·g-1、55.3 mg·g-1;同时其对细菌自身的破坏最小,测得的核酸占比分别为8.7%、8.1%.4种提取方法在A.f菌驯化前后,提取的EPS中多糖与蛋白质的比例范围分别为2.71～3.49和3.24～5.58.该实验结果可为模拟EPS来探索EPS对A.f菌浸出电子废弃物中金属的影响提供参考.【期刊名称】《上海第二工业大学学报》【年(卷),期】2017(034)001【总页数】5页(P1-5)【关键词】电子废弃物;嗜酸氧化亚铁硫杆菌;胞外聚合物;提取【作者】顾卫华;白建峰;卢亮;张洁娜;王景伟【作者单位】上海第二工业大学电子废弃物研究中心,上海201209;上海第二工业大学上海电子废弃物资源化协同创新中心,上海201209【正文语种】中文【中图分类】Q89EPS(Extracellular Ploymeric Substances,胞外聚合物)指的是细菌或真菌在一定条件下分泌于细胞外的一些高分子有机物,主要包括蛋白质、多糖、核酸[1-2]。

A.f 菌(Acidithiobacillus ferrooxidans,嗜酸氧化亚铁硫杆菌)是一种化能自养菌,专性好氧,革兰氏阴性,最佳生长pH值为1.5～3.5,最佳生长温度为25～35°C[3]。

微生物浸出法操作流程Microbial leaching, also known as bioleaching, is a process that uses microorganisms to extract metals from ores. This method is often used to recover valuable metals such as copper, gold, and uranium from low-grade ores. 微生物浸出，又称为生物浸出，是一种利用微生物从矿石中提取金属的过程。

这种方法常用于从低品位矿石中回收铜、金、铀等有价金属。

The microbial leaching process involves the use of bacteria, fungi, or other microorganisms that are capable of oxidizing metal sulfides. These microorganisms break down the sulfide minerals and release the metals in a soluble form, which can then be recovered using various methods. 微生物浸出过程涉及利用能氧化金属硫化物的细菌、真菌或其他微生物。

这些微生物分解硫化物矿物，释放出可溶解的金属，然后可以使用各种方法进行回收。

One of the key advantages of microbial leaching is its environmental friendliness. Unlike traditional mining methods, which involve the use of toxic chemicals such as cyanide, microbial leaching relies on the natural processes of microorganisms to extract metals. This reducesthe impact on the environment and eliminates the need for harmful chemicals. 微生物浸出的一个关键优势是其环保性。

Title: The Appeal of MetalworkingMetalworking, the art of shaping and manipulating metal, is a craft that has captivated humans for centuries. The appeal of metalworking lies in its ability to transform a raw material into functional and aesthetically pleasing objects. This essay will explore the appeal of metalworking, highlighting its historical significance, the skill required to master it, and the artistic and practical benefits it offers.The history of metalworking is rich and varied, with its origins dating back to the Bronze Age. Metalworking has been a fundamental part of human civilization, used for creating tools, weapons, and structures. Over time, metalworking evolved into a sophisticated art form, with different cultures developing unique styles and techniques. The art of metalworking is not just about creating practical objects; it is about creating works of art that reflect the cultural and artistic heritage of a society.Mastering metalworking requires a combination of skill, patience, and creativity. The process of metalworking involves several steps, from selecting the metal to shaping and finishing the final product. Metalworkers must possess a keen eye for design, a steady hand for shaping, and a deep understanding of the properties of metal. The skill required to create a perfect metalworking piece is akin to that of a master craftsman, requiring years of practice and dedication.The artistic benefits of metalworking are manifold. It encourages creativity and innovation, as metalworkers must think outside the box to create new and unique designs. Metalworking can also be used as a form of self-expression, allowing individuals to convey their thoughts and emotions through their creations. The art form is also visually appealing, with its intricate designs and lifelike models captivating audiences.Metalworking also has practical benefits. It can be used to create functional objects, such as tools, jewelry, and sculptures. The durability and strength of metal make it a valuable material for creating lasting and useful objects.In conclusion, the appeal of metalworking lies in its ability to combine simplicity with complexity, creativity with practicality. It is an art form that has stood the test of time, captivating audiences across the globe. Metalworking offers a unique way to explore the world of art, craftsmanship, and personal expression, and it continues to inspire and delight people of all ages.(Word count: 543)。