【作者】 史贵涛；

【导师】 陈振楼； 许世远；

【作者基本信息】 华东师范大学 ， 自然地理学， 2009， 博士

【摘要】 随着城市化过程的加速和人类活动的干扰，有毒金属元素通过各种途径进入土壤环境。金属元素在土壤中不能被微生物分解，可逐步累积，并通过食物链在生物体中富集，或转化为毒性更大的有机化合物，导致土壤环境质量下降，农作物出现中毒，进而影响人类健康；同时还会造成水环境污染和生态环境的进一步恶化，二十世纪发生的十大环境公害事件中有两起直接是由金属元素污染引起的。因此土壤有毒金属元素污染已成为全球环境变化研究的重大问题之一，是近年来国内外环境领域研究的热点。在国家自然科学基金项目“饮用水源地底泥重金属再悬浮释放与水源地水质安全研究”、上海市环保局招标项目“饮用水源地持久性毒害污染物调研及对策”、“上海市持久性毒害污染物溯源调查及对策研究”和上海市基础研究重点项目“上海市饮用水中内分泌干扰物的环境污染过程与控制技术”的资助下，本文对生物毒性较大的痕量金属元素Cd、Pb、As、Hg和Cr在上海土壤中的污染特征进行了详细研究，并对其大气干湿沉降过程、农田土壤-植被迁移过程、农田地表径流输移过程、土壤渗漏淋失过程等生物地球化学行为进行了系统探讨，较完整地估算了有毒金属元素在农田系统中的输入输出通量；此外，论文对pb²⁺和Hg²⁺的等温吸附过程进行了深入探讨。主要得到以下几个方面的结论：（1）上海农田土壤金属元素累积较轻，基本符合农业种植要求，地表灰尘金属元素累积较明显；绝大多数金属元素在农田表层土壤呈现一定的富集。表层土壤Cd以可还原态和弱酸提取态为主，Pb和As均以残渣态为主，Hg则以可还原态和残渣态为主，各元素形态分布在土壤不同深度无明显差异；Cd、Pb、As和Hg在表层土壤的迁移系数分别为36．43％、0．17％、1．08％和2．76％，生物有效态含量占总量的比例依次为Cd＞Hg＞Pb＞As。施肥、工业或生活垃圾肥田等是农田土壤金属积累的主要原因，交通和工业污染是地表灰尘金属元素的主要来源。（2）城市土壤各金属元素含量高于农田土壤，在地表灰尘中的累积更严重；在上海市区，金属元素污染的“热点”区域多分布于城市中心区、主要道路交叉口和工业区附近。溯源分析表明Pb、Zn和Cu主要来自交通污染，土壤Ni则主要来自土壤母质，Cd主要来自工业污染，地表灰尘中的Cr和Ni主要源于大气沉降。（3）小麦植株金属元素含量在不同生长时期表现出明显差异；各器官有毒金属元素含量相比较，果实均较低，而根系普遍高于其它器官；虽然与小麦均为禾本科被子植物，狗尾草对有毒金属元素的累积存在较大差异，果实含量较高，而根的含量相对较低；不同种类的蔬菜对金属元素累积能力存在显著差异，金属元素在蔬菜根中更容易累积。总体来看植物对Cd的富集能力相对较强，对As的富集能力则普遍较弱。土壤中有毒金属元素有效态含量是影响植物体含量的最主要因素，二者符合三次函数关系。作物中有毒金属元素的健康风险评估结果表明，食用小麦和青菜存在一定的致癌风险，食用小麦和蔬菜引起的非致癌风险可以忽略。（4）上海降水pH较低，表现出明显的酸性，Eh主要分布在120mV-200mV间，EC值在夏季相对较低，冬季相对较高。NO₃^-与SO₄^2-当量浓度比表明酸雨为H₂SO₄主导型，H₂SO₄对酸雨的贡献率表现为市区＜郊区＜远郊；TN含量范围为0．37 mg·L^-1-11．69 mg·L^-1，空间上表现为市区＞郊区＞远郊；TC平均含量为19．48mg·L^-1，与TN表现出相同的空间变化规律，降水中TOC占TC的90％以上。降水各金属元素含量表现为Pb＞Cr⁶⁺＞As＞Cd＞Hg，空间上表现为市区较高，郊区和远郊较低；各金属元素在降雨中污染较严重，污染程度表现为Hg＞Pb＞Cd＞As≈Cr⁶⁺；从时间变化看，降雨中Cd、Pb和As在12月含量相对较高，夏季月份含量相对较低。就降雨中形态分布而言，有毒金属元素主要以溶解态存在，各金属元素分配系数K值均大于1。降雨量大小和风向可直接影响各化学成分的含量；降雨中²⁰⁶pb／²⁰⁷pb变化范围为1．1620-1．1748，²⁰⁷pb／²⁰⁸pb在0．40878-0．41103间变化；降雨中N、Cd、Pb和As主要源于交通污染，Cr和TIC主要源于地表灰尘及建筑尘埃，TOC和Hg主要源于燃煤排放。（5）市区金属元素湿沉降通量较高，郊区和远郊相对较低；Cd、Pb、As和Hg在上海地区的大气干湿沉降通量分别为404、1 5500、2934和283μg·m^-2·yr^-1，湿沉降对干湿沉降总量的贡献相对较高；从大气干湿沉降通量的空间分布来看，市区最高，郊区其次，远郊最低，人类活动密集程度的不同导致了有毒金属元素大气沉降通量的差异；分析发现上海是全球大气环境有毒金属元素污染的重要输出地。（6）农田地表径流溶解态金属元素的含量普遍低于降雨；无植被覆盖农田径流溶解态金属含量初始阶段相对较低，随着径流的进行逐渐增大，达到峰值后逐步减小；径流颗粒物粒径小于土壤，金属元素含量则明显高于土壤，其变化趋势同溶解态相似；径流过程颗粒态和总量有毒金属元素的流失表现出明显的初始冲刷效应。植被覆盖地径流中溶解态金属元素含量随径流过程无明显的变化规律；颗粒态金属元素含量随径流浊度的降低而增加；径流事件中溶解态金属元素的EMC值表现为Cr⁶⁺As＞Pb＞Cd≈Hg，地表径流初始冲刷效应不明显。Cd、Pb和Hg在径流过程中以吸附为主，As和Cr⁶⁺以解析为主；降雨中金属元素含量是吸附／解析过程发生的最主要影响因素，Cd、Pb、As和Hg发生吸附／解析过程的临界降雨含量分别为0．095、1．068、1．049和0．066μg·L^-1；无植被覆盖农田径流中溶解态Cd、Pb和Hg含量及颗粒物含量明显高于植被覆盖地，As和Cr⁶⁺则相反。农田地表径流中各元素的固-液分配系数LgK_d表现为As≈Pb＞Hg≈Cd，均存在显著的“颗粒物浓度效应”；径流中颗粒态金属元素的含量主要取决于颗粒物粒径大小和物理性粘粒的含量。（7）土壤渗漏液中各金属元素含量较低，表现为Cr⁶⁺＞Pb＞As＞Hg＞Cd；各元素在不同土层渗漏液中含量变化不一致，Cd和Hg表现为20cm＜40cm＜60cm，Cr⁶⁺含量变化表现出相反的规律，Pb和As则无明显的规律；植物根系分泌大量酸性物质使土壤中金属元素的活性增加，植被覆盖土壤渗漏液中金属元素含量普遍高于裸地土壤渗漏液；土壤颗粒对降雨中Cd、Pb、As和Hg起到明显的吸附作用，使得渗漏液含量明显低于降雨，而Cr⁶⁺则相反。总体来看渗漏量主要受降雨量的影响，二者呈线性相关；生源要素C、N的年渗漏通量在不同深度土层中均表现为20cm＜40cm＜60cm；金属元素渗漏通量大小表现为Cr⁶⁺Pb＞As＞Hg＞Cd，在各土层渗漏液中的变化无明显规律。两种溶液相比较，Cd、As及Cr⁶⁺在地表径流中含量更高，Pb和Hg则在渗漏液中含量较高，吸附作用的差异是造成径流和渗漏液含量不同的主要原因。（8）随溶液中沉积物质量增大，Pb²⁺达到吸附平衡所需时间变短，单位沉积物吸附量和达到吸附平衡后溶液中Pb²⁺浓度变低；沉积物含量大于0．6g·L^-1时对溶液中Pb²⁺的去除率超过95％；沉积物吸附pb²⁺符合Langmuir和Redlich-Peterson等温吸附模型，表现出对Pb²⁺较强的单层吸附能力；pb²⁺在沉积物上吸附的动力学过程符合假二级动力学模型，该模型拟合的平衡吸附量也更接近真实值；Pb²⁺初始吸附速率与初始溶液中沉积物质量无明显的相关性；随溶液中沉积物浓度的增加，吸附速率常数逐渐增大，化学吸附所起的作用也越显著；较高浓度沉积物吸附Pb²⁺的动力学机制能较好符合Elovich方程，但较低浓度沉积物时则相对较差；从吸附速率来看，溶液中沉积物质量较高时，内扩散是整个吸附过程速率的控制步骤，沉积物含量较低时，吸附速率存在多级线性过程，初始阶段非均相扩散是主要控制步骤，但随着时间的延长，其吸附过程转变为沉积物内部的扩散过程。溶液pH值、沉积物粒径、沉积物HA含量、EDTA共存等均可对吸附过程产生影响，Pb²⁺浓度较低情况下Zn²⁺的共存不能对pb²⁺的吸附产生显著影响。Hg²⁺初始含量为10μg·L^-1时，沉积物以物理吸附为主，0．3min时沉积物对Hg²⁺的吸附率均在97％以上；沉积物质量、pH、EDTA共存、沉积物HA含量对Hg²⁺的吸附可产生明显影响，由于吸附质含量较低，Cd²⁺共存和沉积物粒径对Hg²⁺吸附无显著影响。（9）静态柱状沉积物吸附Pb²⁺相对较慢，初始含量越低，平衡浓度越低，从水相向沉积物相的扩散速率也越小；整个静态吸附过程中扩散速率和扩散通量与Pb²⁺初始浓度呈显著的线性正相关关系。研究发现，水葫芦茎粉末是一种高效的生物吸附剂，对溶液中pb²⁺(含量范围0．1-40 mg·L^-1)的吸附率在90％以上；初始Pb²⁺浓度越高，吸附剂质量越低，水葫芦粉末的平衡吸附量越大，吸附过程中活化能增加也越大；假二级动力学模型能较准确的模拟水葫芦粉末对pb²⁺的吸附过程，吸附过程中化学吸附是主要的速率控制步骤；水葫芦粉末吸附pb²⁺的过程存在明显的“两级线性过程”。（10）大气干湿沉降对农田土壤有毒金属元素的输入贡献率均在90％以上；农田系统中Cd、Pb、As和Hg的输入通量分别为0．4020、15．711、3．139和0．250mg·m^-2·yr^-1，均大于输出通量，分别为0．3247、10．5033、1．4944和0．0960mg·m^-2·yr^-1。进入农田中的各金属元素，80％以上的Cd累积在植物体中，近50％的Pb以地表径流形式进入地表水环境，残留在土壤和进入地表水环境的As超过80％，近60％的Hg残留在土壤中。本论文的主要特色：（1）从多学科交叉、宏观现象认识与微观机理实验模拟相结合的研究方法，围绕农田系统中金属元素的“输入”和“输出”过程，深入探讨了金属元素在农田土壤-植物系统中的环境行为。（2）本论文强调“自然条件”与“野外定点观测”，不同与以往对金属元素生物地球化学循环过程（如地表径流、渗漏输移等）研究过多依赖于室内模拟的状况。（3）自行设计了研究金属元素生物地球化学循环过程的若干装置和设备，建立了基于SINEO MDS系列密闭微波制样系统的环境样品处理方法。（4）首次系统研究了上海市大气有毒金属元素的干湿沉降特征及通量，发现上海是全球大气环境中有毒金属的重要输出地。（5）利用同位素示踪技术，对农田系统中金属元素的主要来源进行了分析。（6）对金属离子在城郊小河流沉积物上吸附的动力学过程和影响机制进行了深入探讨，并对一种新型的生物吸附材料进行了探索。（7）系统估算了常规种植条件下，农田系统中有毒金属元素的输入输出通量，计算了有毒金属元素在农田土壤中的累积速率。更多还原

【Abstract】 With the development of urbanization and the interference of intensiveanthropogenic activities,a large amount of toxic metals from such contamination,asindustry,traffic and sewage,were emitted to the soil.The metals,persistent inenvironment,can not be degraded by the microorganism in soil.On the one hand,theaccumulated metals in agriculture soils can be transferred through food chains andconsequently cause adverse health effects on humans.On the other hand,toxic metalsin soil can be transformed to the more harmful organic metal compounds.In addition,under such dynamic conditions,as runoff,resuspension,leaching,and weathering,soils could contribute metals to the hydrosphere and the atmosphere.As a result,theecological environment is becoming deteriorated increasingly.It is noticeable that 2 ofthe 10 major environmental crises in the 20th century were associated to metalpollution.Therefore,toxic metal pollution in soil is one of the major globalenvironmental puzzles,accordingly,arouses a worldwide concern of the researchersand governments.With the support of the National Nature Science Foundation,the bidding projects ofShanghai Environmental Protection Bureau and the Key Program of Shanghai ScienceFoundation,the toxic metal （e.g.,Cd,Pb,As,Hg and Cr） pollution characteristics inShanghai soils were studied.The environmental biogeochemical cycles of metals infarmland were investigated in an all-round way,including atmospheric deposition,transfer in soil-plant system and surface runoff,as well as the leakage in soils.Additionally,the varied in-out put fluxes of metals in farmland were listed.Besides,the isothermal adsorption of Pb²⁺ and Hg²⁺ were explored deeply.The mainconclusions can be summed up as follows.（1） Metals in the agriculture soils were relatively low,up to the national soilstandards for the plants,whereas metals in surface dust have been accumulatedsignificantly.Metals in surface soils accumulated distinctly.Cd in surface soils wasmainly in weak acid-soluble and reducible fractions,while Pb and As were controlledby residual fraction,with the residual and reducible fractions for element of Hg.Thespeciation of metals in the soils of different profile was similar.Moveable coefficientsof Cd,Pb,As and Hg in surface soils were 36.43%,0.17%,1.08% and 2.76%,respectively.The order for bioavailable percentages of metals was as following:Cd＞Hg＞Pb＞As.Fertilization,industrial and domestic wastes were the dominant sources of metals in the farmland soils,while the metal accumulation in dust wasassociated with contaminants introduced by traffic and industry.（2） Metal contents in urban soils were much higher than those in farmland soils,and metal pollution was even severer in urban dust.In Shanghai urban area,thepollution hotspots tended to associate with city core area,major road junctions,andthe regions close to industrial zones.In attempt of identifying the source of metalsthrough geostatistical and multivariate statistical analyses,it was concluded as follows:Pb,Zn and Cu mainly originated from traffic contaminants;soil Ni was associatedwith natural concentration;Cd largely came from point-sourced industrial pollution;and Cr,Ni in dust were mainly related to atmospheric deposition.（3） Metal contents in wheat were varied during the different growing stages.As forthe wheat organs,wheat fruit accumulated less metal,whereas metal contents in rootwere elevated.Although both Setaria viridis and wheat belongs to Gramineae,theaccumulation of metals in Setaria viridis was different,with higher metal contents infruits and low values for roots.Vegetable species could influence metal concentrations.Generally,higher metal enrichment was present in vegetable roots.Among theinvestigated metals,the bioconcentration factor of Cd in plants was the highest,lowvalue in plants for As.Metal contents in plants were dominated by bioavailablefraction in surface farmland soils,and a cubic function was fitted well.The results ofhealth risk assessment indicated that carcinogenic metals （Cd and As） in wheat andBrassica campestris L.ssp.Chinnesis could cause high risks,and the risk ofnoncarcinogenic metals （Pb and Hg） in vegetables and wheat can be ignored.（4） The rainwater in Shanghai was the acid rain,with a relatively low pH.Redoxpotential of the rain arranged from 120mV to 200mV mainly,and electricalconductivity in rainfall showed elevated values in winter,low numbers for summer.The ratios of NO₃^-contents to SO₄^2- levels revealed that H₂SO₄ controlled the acidityin the rainwater.Spatial analysis indicated that contributing rate of H₂SO₄ in the acidprecipitation was high in the rural area,followed by suburb and the city.Totalnitrogen （TN） contents in rain were from 0.37 mg·L^-1 to 11.69 mg·L^-1,and the averagevalue was 19.48mg.L^-1 for total carbon （TC）.Spatial distribution of TN and TC inrains was regular,and the higher contents were in urban precipitation,with the lowervalues in rural rains.Total organic carbon was the main component of TC in therainwater.Metal contents in rains varied in the order of Pb＞Cr⁶⁺＞As＞Cd＞Hg,with thepollution degree of Hg＞Pb＞Cd＞As≈Cr⁶⁺.As to the metal concentration varieties in rainfalls,higher metal contents were present in urban rain,while low values were insuburban and rural precipitation.Metal concentrations in rains were different in variedmonths,in general,Cd,Pb and As in December rainfall were elevated,with the lowvalues in summer.The value of K,solid-liquid distribution coefficients of metals inrainwater,was larger than 1,meaning that soluble fraction was dominant.There werebetter correlations between metal contents in rainwater and precipitation as well aswind directions.The stable isotope compositions of Pb in rains were 1.1620-1.1748for ²⁰⁶pb/²⁰⁷pb and 0.40878-0.41103 for ²⁰⁷pb/²⁰⁸Pb.Sources identification ofpollutants in rains demonstrated that N,Cd,Pb and As were from the trafficcontaminants,while Cr and TIC （total inorganic carbon） were mainly correlated withsurface dust and building site dust,TOC and Hg related to coal combustion.（5） Wet atmospheric deposition fluxes of metals in urban area were higher thanthose in suburban and rural areas.It was computed that bulk atmospheric depositionfluxes of Cd,Pb,As and Hg in Shanghai were 404,15500,2934 and 283μg·m^-2·yr^-1severally,and wet atmospheric deposition made a major contribution to the totaldeposition.It was concluded that various types and intensities of human activitieswere the main reasons for the spatial variation of metal atmospheric deposition fluxes.According to the atmospheric deposition and emissions of metals,it could be gottenthat there were more than 200t （Pb） and 7t （Hg） transported to other regions.（6） Dissolved metal concentrations （DMC） in farmland runoff were lower thanthose in the rainfall.For the DMC in bare farmland runoff,the values increasedsteadily with relatively small valuesat the beginning,subsequently,the numbersdecreased after the peak contents.Meanwhile,metal contents of particles （PMC） inthe runoff were higher than those in surface soils,of which the grain size wasrelatively larger.The change of PMC in the process of runoff events was similar to theDMC trend.As a whole,particle and total metals losses in bare farmland runoff couldbe characterized by the first flush effect.Compared the DMC in bare land runoff,there were no consistent trend of DMC in plant-covered farmland runoff processes,whereas the PMC increased with the reduction of turbidity of runoff.Event meanconcentrations of dissolved metals in the plant-covered land runoff were present in theorder of Cr⁶⁺＞As＞Pb＞Cd≈Hg,and the first-flush phenomenon of these elements werenot obvious.Metals of Cd,Pb and Hg in rainwater were absorbed significantly by thesoil particles in the runoff,and desorption of soils was dominant for As and Cr⁶⁺.Particle levels and dissolved cotents of Cd,Pb and Hg in bare land runoff were higher than those in plant-covered land runoff,but As and Cr⁶⁺ showed the oppositediscipline.It was the metal contents of rainwater what determines which process wasdominant,adsorption or desorption.The critical levels of Cd,Pb,As and Hg in rainswere 0.095,1.068,1.049 and 0.066μg·L^-1 respectively.Furthermore,the solid-liquiddistribution coefficient （lgK_d） was varied among metals （As≈Pb＞Hg≈Cd）,on whichthe particle concentration effect was remarkable.The grain size and clay content ofthe particles in runoff determined the PMC in farmland runoff.（7） Metal levels in the in soil leaching solution were relatively low,and the value ofCr⁶⁺ was highest,followed by Pb＞As＞Hg＞Cd.As for the contents variation indifferent layers of soil leaching solution,Cd and Hg contents in the depth of 20cmwere higher than those in the depth of 40 cm,the lowest for 60 cm.However,Cr⁶⁺was present the opposite distribution.There were no consistency and regularity for theelement Pb and As contents.Broadly speaking,metal levels in the plant-coveredfarmland soil leaching solution were higher than those in the bare land solution,whichwas caused by the acidic component of root exudates.Cd,Pb,As and Hg wereadsorbed by soil particles significantly,leading to lower levels in soil leachingsolution,meantime Cr was desorbed from the soils and higher value was investigatedin the leaching solution.There was a better linear correlation between precipitationand leakage.The elements of C and N leakage fluxes in different depth of soil layerswere present in the order of 20cm＜40cm＜60cm,and metals were quite different,noconsistent tendency observed in varied layer soil solution.Among the 5 studied metals,Cr⁶⁺ leakage flux was the largest,followed by the descending order of Pb,As,Hg andCd.Comparison of metal levels in varied solutions showed that Cd,As and Cr⁶⁺contents in runoff were higher than those in soil leaching solution,the oppositediscipline observed for Pb and Hg.Adsorption intensity was the primary cause ofdifferent metal levels in the two types of solutions.（8） Equilibrium time of adsorption increased with the increase of sediment mass insolution,while both adsorbed Pb²⁺ on per unit of sediment and Pb²⁺ concentration inthe solution after equilibrium decreased.More than 95% of Pb²⁺ in solution wasremoved when sediment contents larger than 0.6g·L^-1.The experimental data closelyfollowed by both Langmuir and Redlich-Peterson isotherms,and sediment had aconsiderably high Langmuir monolayer capacity of Pb²⁺.Both pseudo-first-order andpseudo-second-order kinetics were tested and it was found that the latter gave a betterexplanation of the adsorption process.The equilibrium adsorption capacities calculated from the pseudo-second-order model could represent the true value.Therewas no significant correlation between initial adsorption rate of Pb²⁺ and the amountof sediment in solution.However,the pseudo-second-order rate constant increased inthe solution with more adsorbent,namely chemical adsorption controlled the process.Elovich equation could explain the mechanism of sorption in the solution with highercontents of sediment;nevertheless,the process of low concentration of adsorbentadsorbing Pb²⁺ disagreed well with Elovich equation.In terms of adsorption rate inthe sorption,intra-particle diffusion dominated in the more sediment solution.On theother hand,multi-linearity was presented for the adsorption rate in less adsorbentsolution.The first,sharper portion represented adsorption on the external surface.Thesecond portion indicated Pb²⁺ diffused gradually into the interior of particles andintra-particle diffusion controlled.pH of the solution,co-existence of EDTA,sedimentgrain size and humic acid level could influence the adsorption of Pb²⁺ onto sedimentgreatly.Adsorption rate of Hg²⁺ on sediment was greater than 97% after 0.3 min withthe initial content of 10μg·L^-1,and physical adsorption controlled in the process.Theimpacting factors of Hg²⁺ adsorbed on sediment mainly included adsorbent amount,pH of solution,co-existence of EDTA and sediment humic acid content.It wasobserved that the co-existence of Cd²⁺ could not impact adsorption of Hg²⁺ due to thetrace initial level of adsorbate.（9） Adsorption rate of Pb²⁺ onto sediment core statically was relatively smaller.Lower initial level of Pb²⁺ resulted in the lower equilibrium content and smallerdiffusion rate in interface between water and sediment,and initial contents of Pb²⁺were correlated well with diffusion rates and diffusion fluxes.Stem powder ofEichhornia crassipes （SPE） could truly be termed as a high-effective and low-costadsorbent,and the adsorption rate of Pb²⁺ with varied initial levels of 0.1-40 mg·L^-1was above 90%.Both elevated initial Pb²⁺ and less SPE could conduce to greaterequilibrium uptake and activation energy variation.It was revealedpseudo-second-order kinetics provided a better explanation of the adsorption of Pb²⁺on SPE.In terms of adsorption rate in the sorption,chemical adsorption controlled theadsorption rate.Furthermore,two-step linearity was presented for the adsorption rate.（10） Suppose the farmland was a black box,inputs of toxic metals in the farmlandwere dominated by atmospheric deposition,with the contribution rates of more than90%.The input fluxes ofCd,Pb,As and Hg were 0.4020,15.711,3.139 and 0.250mg·m^-2·yr^-1 respectively,which were smaller than the outputs values of 0.3247, 10.5033,1.4944 and 0.0960 mg·m^-2·yr^-1.As far as the environmental fates of themetals introduced to farmland were concerned,more than 80% of Cd wasaccumulated in plants;about 50% of Pb was transported to surface water by runoff;larger than 80% of As was accumulated in soils and lost with runoff;residue of Hg insoils accounted for nearly 60% the input.Innovations of this PhD dissertation are mainly:（1） Based on the intersecting of several subjects and the combination ofmacroscopic phenomena and microcosmic mechanisms,the environmental behaviorsof toxic metals in soil-plant system were investigated according to the input-output ofmetals in farmland.（2） Paying more attention to the natural conditions and field observations,the studyon biogeochemical cycles was improved greatly;and the traditional researches toomuch relied on the simulation experiment.（3） Some new equipment for sampling and observation were developed in thisstudy;and methodology for sample preparation was conducted with tha aid of SINEOMDS micro-wave digestion system.（4） Wet and dry deposition of toxic metals in Shanghai was studied completely,andit was found that waste gas discharge of Shanghai was a main source of metals in theglobal atmosphere.（5） Major sources of toxic metals in soils and atmosphere were identified by use ofisotope tracer technique.（6） Kinetics and isotherms adsorption of metal ions onto small rever sedimentswere investigated thoroughly;and a new type of biological material adsorbing metalion was explored.（7） The input-output fluxes of toxic metals in farmand were estimated systemically,and the accumulation rates of metals in soils were computed.更多还原