苏南经济快速发展区土壤Cu、Ni、Pb、Zn形态及其有效性定量分析——以昆山市为例

研究了江苏省昆山市农田土壤有效态Cu、Ni、Pb、Zn各形态含量及其有效性。结果表明,土壤重金属Cu、Ni、Pb、Zn各形态含量以残渣态有机质结合态铁锰氧化物结合态碳酸盐结合态、可交换态,残渣态含量明显高于其他形态。Cu和Pb有机质结合态所占比例相对也较高,分别达36.09%和28.30%。土壤可交换态含量、碳酸盐结合态含量、Fe-Mn氧化物结合态含量及残渣态含量均以Zn最高;土壤有机质结合态含量以Cu最高;土壤可交换态含量变异系数、土壤碳酸盐结合态含量变异系数及土壤Fe-Mn氧化物结合态含量变异系数以Ni为最大;土壤有机质结合态含量变异系数以Zn最大;土壤残渣态含量变异系数以Pb最大。土壤铁锰氧化物结合态铜和可交换态铜对土壤有效态铜含量影响最大;土壤可交换态镍含量对土壤有效态镍含量最大;土壤铁锰氧化物结合态铅和有机质结合态铅对土壤有效态铅含量影响最大;土壤可交换态锌和碳酸盐结合态锌对土壤有效态锌含量影响最大。     

水稻子实对不同形态重金属的累积差异及其影响因素分析

在分析成都平原核心区土壤重金属(Cd、Cr、Pb、Cu、Zn)全量、各形态含量及相应点位种植的水稻子实重金属含量的基础上,通过统计分析、空间插值及线性回归方程的模拟,研究了土壤Cd、Cr、Pb、Cu、Zn全量的空间分布状况、各形态重金属含量统计特征,以及水稻子实对重金属各形态的累积差异及其影响因素。结果表明,成都平原水稻土重金属污染较轻,除Cd外,均低于国家土壤环境质量二级标准。土壤中重金属的可交换态含量均较低,Cd主要以铁锰氧化态存在,Cr、Cu、Zn、Pb主要以残渣态存在。水稻子实对5种重金属的累积效应顺序为:Cd>Zn>Cu>Pb>Cr。与水稻重金属累积关系密切的重金属活性形态(可交换态、碳酸盐结合态、铁锰氧化物结合态和有机物结合态)主要有:Cd的碳酸盐结合态、Cr的可交换态、Pb的有机物结合态和Cu的碳酸盐结合态含量;Zn各活性形态对水稻子实含量的影响不明显。土壤理化性质对不同活性形态重金属元素的影响效应各不相同。活性态Cd主要受有机质、pH和容重的影响;活性态Cr与pH、有机质、CEC和容重密切相关;活性态Pb与有机质、容重、中细粉粒、砂粒等均有密切的关系;Cu的活性主要受粘粒、有机质含量的影响;Zn的有效性主要受pH、有机质、砂粒、容重的影响。总的看来,对土壤Cd、Cr、Pb、Cu、Zn各活性形态含量影响效应较强的是有机质、pH、容重,而与土壤吸附性能密切相关的颗粒组成、CEC的影响不甚明显。     

海南岛砖红壤中铅、镉的化学形态与转化

采用土培实验和连续提取.原子吸收分光光度法,研究了重金属Pb、Cd在海南岛花岗岩砖红壤中的形态组成、外源Pb、Cd污染及化学修复剂磷、钙、硫对土壤重金属形态的影响.结果表明:在供试原土壤中,重金属Pb的化学形态以结合态和残余态为主,土壤有效态Pb含量较低,其中残余态Pb>有机质结合态Pb>铁锰氧化物结合态Pb>碳酸盐结合态Pb>交换态Pb>水溶态Pb,说明土壤Pb的环境风险较低;重金属Cd的化学形态以铁锰氧化物结合态和碳酸盐结合态为主,土壤中交换态Cd含量较高,其中铁锰氧化物结合态Cd>碳酸盐结合态Cd>交换态Cd>有机结合态Cd>残余态Cd>水溶态Cd,说明土壤Cd的环境风险较高.当外源Pb、Cd污染土壤时,有铁锰结合态Pb>残余态Pb>有机态Pb>碳酸盐结合态Pb>交换态Pb>水溶态Pb,交换态Cd>铁锰氧化物结合态Cd>碳酸盐结合态Cd>残余态Cd>有机态Cd>水溶态Cd的趋势.向污染土壤施加化学改良剂过磷酸钙、硫化钠和石灰,能显著降低水溶态Pb、Cd和交换态Pb、Cd的含量,并使有机结合态Pb、碳酸盐结合态Pb和铁锰氧化物结合态Pb含量下降,但残余态Pb、碳酸盐结合态Cd、铁锰氧化物结合态Cd和有机态Cd有增加的趋势,残余态Cd的含量基本稳定.     

长春市城区土壤中Pb、Cu、Zn、Cd及Cr化学形态特征

为弄清长春市城市土壤中Pb、Cu、Zn、Cr及Cd的化学形态分布特征,系统采集了26件城市表层(0~20 cm)土壤样品,采用连续提取法对重金属各化学形态含量进行了测定。结果表明:Pb、Zn、Cu及Cr主要以残渣态存在,其次是铁锰氧化物结合态、腐殖酸结合态和强有机结合态占有次要地位,离子交换态和水溶态所占比例均较低;Cd则主要以碳酸盐结合态存在,同时,水溶态和离子交换态所占比例较高。残渣态Pb和Zn在城区表层土壤中所占比例较近郊土壤中略有下降,但幅度不大,除Cu外,其余各元素易迁移、高生物有效性的水溶态在城区表层土壤中所占比例略有上升。Pearson相关分析结果表明,各元素残渣态与全量均呈极显著正相关,其它各活性态与全量间的相关程度与重金属种类有关。土壤pH值和Fe、Mn含量对重金属的化学形态的影响也与重金属种类有关,而且,同一重金属的不同存在形态受土壤pH值和Fe、Mn含量的影响程度也不同。     

水稻籽实对不同形态重金属的累积差异及其影响因素分析

在分析成都平原核心区土壤重金属（Cd、Cr、Pb、Cu、Zn）全量、各形态含量及相应点位种植的水稻籽实重金属含量的基础上，通过统计分析、空间插值及线性回归方程的模拟，研究了土壤Cd、Cr、Pb、Cu、Zn全量的空间分布状况、各形态重金属含量统计特征，以及水稻籽实对重金属各形态的累积差异及其影响因素。结果表明，成都平原水稻土重金属污染较轻，除Cd外，均低于国家土壤环境质量二级标准。土壤中重金属的可交换态含量均较低，Cd主要以铁锰氧化态存在，Cr、Cu、Zn、Pb主要以残渣态存在。水稻籽实对5种重金属的累积效应顺序为：Cd＞Zn＞Cu＞Pb＞Cr。与水稻重金属累积关系密切的重金属活性形态（可交换态、碳酸盐结合态、铁锰氧化物结合态和有机物结合态）主要有：Cd的碳酸盐结合态、Cr的可交换态、Pb的有机物结合态和Cu的碳酸盐结合态含量；Zn各活性形态对水稻籽实含量的影响不明显。土壤理化性质对不同活性形态重金属元素的影响效应各不相同。活性态Cd主要受有机质、pH和容重的影响；活性态Cr与pH、有机质、CEC和容重密切相关；活性态Pb与有机质、容重、中细粉粒、砂粒等均有密切的关系；Cu的活性主要受粘粒、有机质含量的影响；Zn的有效性主要受pH、有机质、砂粒、容重的影响。总的看来，对土壤Cd、Cr、Pb、Cu、Zn各活性形态含量影响效应较强的是有机质、pH、容重，而与土壤吸附性能密切相关的颗粒组成、CEC的影响不甚明显。     

新乡市环宇大道工业区周边土壤重金属的污染特征和评价

通过实地采样及室内化学分析的方法,研究了新乡市环宇大道工业区周边土壤Pb、Cd、Ni、Zn、Cu和Cr 6种重金属污染特征和风险评价,并应用Tessier五步连续萃取的方法对土壤中超标的Cd,Ni和Zn进行形态分析。结果表明:(1)土壤中Pb、Cd、Ni、Zn、Cu和Cr的平均含量分别是63.08 mg kg-1、176.85 mg kg-1、307.2 mg kg-1、485.6 mg kg-1,38.7 mg kg-1和47.9 mg kg-1,Pb、Cu、Cr平均含量达标,Cd、Ni、Zn平均含量均超标,分别是国家土壤环境质量二级标准的176.85、5.12、1.62倍。(2)Ni和Zn主要以铁锰氧化物结合态和残渣态存在,Cd主要以铁锰氧化物结合态存在,其次为碳酸盐结合态,3种重金属的迁移能力依次为:Cd>Zn>Ni。(3)每种重金属都存在不同程度的潜在生态风险,Cd的潜在生态风险最大并构成了很强的危害。     

施污土壤与污泥中Cu、Pb、Cd、Zn的形态分布

污泥中的重金属元素是限制其大规模农田利用的重要因素。施污土壤和污泥中重金属的形态研究可以用来评价土壤中重金属的生物有效性以及它们在土壤中的移动性。用修正BCR三步连续提取法进行分步提取研究了污水污泥和施污后的西红柿地土壤中Cu、Pb、Cd、Zn的形态分布状况。施用污泥堆肥10t hm-2后的土壤中Cu、Pb、Cd、Zn的全量与各种形态含量无明显增加,Cu、Pb、Zn含量远低于国家土壤环境质量标准。土壤中Cu的各种形态分布关系是:残渣态>可还原态=可氧化态>可交换态和弱酸溶解态,Cu在土壤中的存在是以最稳定的残渣态为主。堆肥污泥与干化污泥相比,残渣态Cu的比例明显增加。土壤中Pb的各种形态分布关系是以残渣态和可还原态为主,但可氧化态的分布比例最小。土壤中Cd的可交换态、可还原态和残渣态各占据相等的含量,但可氧化态Cd的含量几乎为零。Zn在土壤中的各种形态分布关系是:可交换态和弱酸溶解态>可氧化态>可还原态>残渣态,Zn在土壤中的存在是以最易迁移的可交换态和弱酸溶解态为主。这些金属元素在土壤中的相对稳定性顺序为:Cu>Pb>Cd>Zn。Zn在土壤中的移动性要远高于Cu。     

二乙三胺五醋酸萃取后污染土壤中重金属Pb、Cu的形态分布

以硫铜矿尾矿区域土壤和库区周边受污染的农田土壤为研究对象,采用Tessier连续提取法研究了二乙三胺五醋酸(DTPA)萃取前后受污染土壤中的重金属Pb、Cu的形态变化。结果表明,两类污染土壤中的重金属Pb、Cu的形态分布各有差异,矿区土壤Pb、Cu主要以残渣态为主,农田土壤以有机结合态为主。在0.01molL-1浓度的条件下,DTPA对供试土壤Pb的萃取能力较其对Cu萃取能力强;经DTPA萃取后土壤中Pb、Cu的残渣态、碳酸盐结合态、铁锰氧化物结合态、交换态的含量分别有所下降。两种类型土壤中Pb、Cu残渣态、碳酸盐结合态、铁锰氧化物结合态、交换态变幅表现各异;矿区土壤和农田土壤中Cu的有机结合态含量有所增加,矿区土壤和农田土壤中Pb的有机结合态含量却表现各异,矿区土壤其含量有所增加,而农田土壤其含量却明显减少。     

废旧汽车拆解区土壤重金属分布及Pb、Zn生物有效性分析

为了解废旧汽车拆解区土壤重金属污染问题,采集某废旧汽车拆解厂汽车拆解区垂向0~1000 cm深度的土壤样品,对重金属Cu、Zn、Pb、Cr、Ni、Cd、Hg和As元素含量进行检测和污染评价,并对土壤中重金属Pb和Zn的不同形态进行分析研究。研究发现:废旧汽车拆解区表层土壤存在一定程度的Cu、Zn、Pb、Cr、Ni、As污染,其中,Pb、Zn、Cu含量严重超标,呈现Cu、Ni、Pb、Cr、Zn、As多种元素复合污染的特性。同时,拆解区土壤中重金属含量随土壤深度显著下降,但是,Pb和As的污染超标深度可达150 cm。拆解区土壤中可离子交换态的Pb含量最低,土壤pH值对各种形态重金属Pb的控制作用不显著,随着土壤垂向深度的增加,可氧化态和弱酸提取态Pb的比例迅速降低,残渣态Pb的质量分数逐渐提高,Pb的生物有效性下降。土壤pH对可Zn的生物有效性具有显著相关性,弱酸性土壤中以生物有效性高的形态Zn存在,中性土壤中以可还原态和可氧化态Zn为主。     

碳酸钙对石灰性土壤颗粒组成测定的影响

采取化学分析和Tessier连续提取法,对西宁市6个功能区城市土壤重金属Cu、Zn、Pb和Cd的含量及形态进行研究。结果表明:西宁市各功能区土壤的Cu、Zn、Pb和Cd的全量分别是全国土壤相应重金属几何平均值的1.9~5.2,1.9~6.9,0.8~4.0,7.4~11.1倍,4种重金属污染比较严重。6个功能区的重金属Cu、Zn、Pb和Cd含量进行差异显著性分析,结果是广场区Cu的含量与风景区的差异不显著(P>0.05),但与其他4个功能区差异显著(P<0.05);风景区与开发区差异显著(P<0.05),但与其他4个功能区差异不显著(P>0.05);开发区Zn的含量与商业区和居民区的差异显著(P<0.05),而其他各功能区间差异均不显著(P>0.05);各功能区Pb和Cd的含量均无显著差异(P>0.05)。研究土壤中重金属的化学形态有较大的差异,Cu以残渣态和有机结合态为主;Zn以残渣态和铁锰氧化物结合态为主;Pb和Cd以残渣态为主。Cu活性相对较高的土壤出现在风景区、矿冶区和居民区,Zn活性相对较高的土壤出现在风景区和广场区,Pb活性相对较高的土壤出现在风景区和居民区,Cd活性相对较高的土壤出现在矿冶区和开发区,研究土壤中4种重金属均具有一定的生物有效性和潜在的生态危害性。     

Heavy metal characterization of river sediment in Hanoi,Vietnam

Abstract

Industrial and municipal waste water is directly discharged to rivers in Hanoi, Vietnam. Sediments were collected from different sites of three rivers in the industrialized and densely‐populated area of Hanoi City and examined for total heavy metals and metal fractions using sequential extraction. Concentration of the total heavy metals ranged from the background levels to over the maximum permissible levels to crop growth. Concentrations of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) ranged from 0.27 to 4.50,78 to 517, 37 to 309, 37 to 174, 43 to 361, and 93 to 4,950 mg kg^‐1, respectively. Total concentration of heavy metals varied from site to site and tended to be higher in the site where manufacturing companies are located. Heavy metals were accumulated in the site and were not moved away to be redistributed in the whole area. Distribution of heavy metals in different chemical forms in the air‐dry state depended on their total concentration. In the low concentration range, Cr, Cu, Ni, and Zn were for the most part concentrated in the residual fraction. When concentration is equal to or above the maximum permissible level to crop growth, Cr, Ni, and Zn were mostly concentrated in the iron‐manganese (Fe‐Mn) oxides fraction and Cu was in the organic fraction. Irrespective of the total concentration, Cd was highly associated with the exchangeable and carbonate fractions, while the sum of the Fe‐Mn oxides and residual fractions accounted for 80 to 96% of total Pb.     

Relationships of Heavy Metals in Natural Lake Waters with Physico-chemical Characteristics of Waters and Different Chemical Fractions of Metals in Sediments

The relationships between heavy metal concentrations and physico-chemical properties of natural lake waters and also with chemical fractions of these metals in lake sediments were investigated in seven natural lakes of Kumaun region of Uttarakhand Province of India during 2003–2004 and 2004–2005. The concentrations of Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb in waters of different lakes ranged from 0.29–2.39, 10.3–38.3, 431–1407, 1.0–6.6, 5.3–12.1, 12.6–166.3, 0.7–2.7 and 3.9–27.1 μg l^?1 and in sediments 14.3–21.5, 90.1–197.5, 5,265–6,428, 17.7–45.9, 13.4–32.0, 40.0–149.2, 11.1–14.6 and 88.9–167.4 μg g^?1, respectively. The concentrations of all metals except Fe in waters were found well below the notified toxic limits. The concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were positively correlated with pH, electrical conductivity, biological oxygen demand, chemical oxygen demand and alkalinity of waters, but negatively correlated with dissolved oxygen. The concentrations of Cr, Ni, Zn, Cd and Pb in waters were positively correlated with water soluble + exchangeable fraction of these metals in lake sediments. The concentrations of Zn, Cd and Pb in waters were positively correlated with carbonate bound fraction of these metals in lake sediments. Except for Ni, Zn and Cd, the concentrations of rest of the heavy metals in waters were positively correlated with organically bound fraction of these metals in lake sediments. The concentrations of Cr, Mn, Ni, Cu and Zn in waters were positively correlated with reducible fraction of these metals in lake sediments. Except for Cd, the concentrations of rest of the metals in waters were positively correlated with residual fraction and total content of these heavy metals in lake sediments.     

长三角和珠三角农业土壤中铅、铜、镉的化学形态与转化

研究了重金属Pb、Cu、Cd在长江三角洲和珠江三角洲土壤中的转化及不同Pb、Cu、Cd负荷水平对土壤重金属形态的影响。结果表明:未明显污染土壤中重金属主要以残余态为主,可提取态组分的比例Cd>Cu>Pb,但不同土壤之间有较大变化;随着土壤重金属负荷的提高,土壤中交换态重金属的比例增大,残余态比例下降,有效性提高,对环境威胁增大;当重金属加入量较低时,重金属优先向氧化物结合态、有机质结合态转化,而当加入量较高时,向交换态和碳酸盐结合态转化的比例明显增加;pH和土壤组分对重金属在土壤中的转化有显著影响,土壤pH下降可使交换态Cd、Cu、Pb的比例递增。     

新乡市寺庄顶污灌区土壤中重金属的形态分布及生物有效性研究

对长期电池废水灌溉的新乡市寺庄顶污灌区和对照区土壤重金属进行取样分析,结果表明,对照区土壤中Cd,Ni,Zn,Cu和Cr含量都能达标,污灌区土壤中Cr含量能达标,Cd,Ni,Zn和Cu的含量超标,其平均含量分别为65.31,1 196.64,2 799.25,145.78 mg/kg,是国家土壤环境质量二级标准的108.85,19.94,9.33和1.46倍。形态分析结果表明,污灌区污染最严重的Cd主要以铁-锰氧化物结合态存在,所占比例平均为56.84%;Ni主要以铁-锰氧化物结合态和残余态存在,所占比例平均为37.44%和39.55%;Zn主要以残余态存在,所占比例平均为78.24%;Cu主要以有机结合态存在,所占比例平均为57.70%;Cr主要以有机结合态和残余态存在,所占比例平均为45.55%和34.18%。与对照相比,污灌降低了Cd,Ni,Zn,Cu和Cr残余态所占比例,提高了重金属迁移能力和生物有效性。在4种超标重金属中Cd可交换态所占比例最高,平均为24.54%,由于其生物有效性最高,Cd迁移能力和植物毒性最值得关注。     

Heavy‐Metal Contamination of Soil and Vegetables in Wastewater‐Irrigated Agricultural Soil in a Suburban Area of Hanoi,Vietnam

The To Lich and Kim Nguu Rivers, laden with untreated waste from industrial sources, serve as sources of water for irrigating vegetable farms. The purposes of this study were to identify the impact of wastewater irrigation on the level of heavy metals in the soils and vegetables and to predict their potential mobility and bioavailability. Soil samples were collected from different distances from the canal. The average concentrations of the heavy metals in the soil were in the order zinc (Zn; 204 mg kg^?1) > copper (Cu; 196 mg kg^?1) > chromium (Cr; 175 mg kg^?1) > lead (Pb; 131 mg kg^?1) > nickel (Ni; 60 mg kg^?1) > cadmium (Cd; 4 mg kg^?1). The concentrations of all heavy metals in the study site were much greater than the background level in that area and exceeded the permissible levels of the Vietnamese standards for Cd, Cu, and Pb. The concentrations of Zn, Ni, and Pb in the surface soil decreased with distance from the canal. The results of selective sequential extraction indicated that dominant fractions were oxide, organic, and residual for Ni, Pb, and Zn; organic and oxide for Cr; oxide for Cd; and organic for Cu. Leaching tests for water and acid indicated that the ratio of leached metal concentration to total metal concentration in the soil decreased in the order of Cd > Ni > Cr > Pb > Cu > Zn and in the order of Cd > Ni > Cr > Zn > Cu > Pb for the ethylenediaminetetraaceitc acid (EDTA) treatment. The EDTA treatment gave greater leachability than other treatments for most metal types. By leaching with water and acid, all heavy metals were fully released from the exchangeable fraction, and some heavy metals were fully released from carbonate and oxide fractions. The concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in the vegetables exceeded the Vietnamese standards. The transfer coefficients for the metals were in the order of Zn > Ni > Cu > Cd = Cr > Pb.     

污染水稻土中重金属的形态分布及其影响因素

通过BCR3步提取法研究了江西省贵溪铜冶炼厂污染区水稻土中重金属的形态分布。研究表明,废渣场渗滤液污染区域(渣场区)的污染较污水灌溉污染区(污灌区)严重,渣场区土壤中Cu、Pb、Cd的含量高于污灌区,而污灌区土壤Ni含量较高。在表层(0～20cm)水稻土中,Cu以可氧化态为主,Pb以可还原态和可氧化态为主,Cd以酸溶态为主,Ni以残渣态为主,不同重金属元素的有效态所占总量百分比大小顺序是Cd>Cu>Pb>Ni。土壤重金属不同形态之间也呈现一定的相关性,说明Cu与Pb、Cd、Ni之间具有同源性。土壤pH主要影响了污灌区中Cu的形态分布,以及渣场区土壤酸溶态Ni的分布。土壤有机质含量对各重金属形态分布的影响不明显。     

Distribution of Trace Elements in Soils from the Sudbury Smelting Area (Ontario,Canada)

The sequential extraction procedure proposed by the European Commission Measurement and Testing Programme, combined with Scanning Electron Microscopy and Energy Dispersive X-ray Analysis(SEM/EDS), was applied to identify and quantify the chemical andmineralogical forms of Cu, Ni, Fe, Mn, Zn, Pb, Cr and Cd presentin the topsoil from a mining and smelting area near Sudbury (Ontario, Canada). The possible mobility of the chemical forms was also assessed. The metal fractions: (1) soluble and exchangeable, (2) occluded in manganese oxides and in easily reducible iron oxides, (3) organically bound and in form of sulphides, (4) residual mainly present in the mineral lattice structures were separated. Cu and Ni were the major metallic contaminants, occurring in soils in broad ranges of concentrations: Cu 11–1890 and Ni 23–2150 mg kg^-1. Cu was uniformly distributed among allthe extracted fractions. Ni was found associated mainly withthe residual forms, accounting for 17–92%, with an averageof 64%, of the total Ni present in the soils. Fe, Mn, Zn,Pb, Cr and Cd, while occurring in most analysed samples innormal soil concentrations, were primarily held in theresidual mineral fraction (on average >50%). The solubleand exchangeable forms made a small contribution (≤8.1%)to the total content of metals extracted. At least 14% ofthe total Cd, Mn and Pb was mobilised from the reducibleforms. The oxidizable fraction assumed mean values higher than10% only for Pb and Zn. Statistical treatment of the experimental data showed significant correlations between totalmetal content of the soils, some soil properties such as pH value, clay and organic matter content, and metal concentrationsin the various fractions. SEM/EDS analysis showed Fe in form ofoxides and sulphides in soils and Cu, Ni, Mn, Zn and Cr in association with iron oxides. Numerous black carbonaceous particles and precipitates of aluminium fluoride salts, observedin the solid residue left after `total’ digestion, were found tocontain Fe, Ni and Cr.     

Chemical extractability and availability of heavy metals after seven years application of organic wastes to a citrus soil

Abstract. The chemical extractability of heavy metals introduced into the soil during 7 years application of sewage sludge, composted municipal solid waste and sheep manure, and their availability to citrus plants were studied. The total content of metals in the soil (0-20 cm)was increased by the use of sludges and compost, but only the Ni content in the saturation extracts of soil was significantly increased. Total Cd, Cr, Cu, Ni, Pb, and Zn were sequentially fractionated into water-soluble plus exchangeable, organically bound, carbonate-associated, and residual fractions. Most of the heavy metals were present in carbonate and residual fractions, although substantial amounts of water-soluble plus exchangeable Cd, and organically bound Cu and Ni were found. No significant increases in the metal contents in leaves and orange fruits were observed, with the exception of Pb in leaves. Several statistically significant correlations between metal content in plants, metal content in soil fractions, and chemical characteristics of soil were also found.     

渤海湾各形态重金属的地球化学特征及其环境意义

根据2008年对渤海湾的调查,重点研究了渤海湾湾内和湾口柱状沉积物重金属的生物地球化学特征,通过剖析不同形态重金属的特征,结合渤海湾生态环境信息的综合分析,系统探讨了渤海湾沉积物重金属的演变趋势、影响控制因素以及潜在生态风险。结果表明,湾内海河口附近沉积柱重金属含量有几次突变,20～22cm段极小值可对应1939年海河北系的洪水,10～12cm段极小值可对应1963年海河南系的洪水,1963年至今重金属含量有逐渐增加的趋势。不同形态重金属百分含量从大到小为：残渣态〉铁锰氧化物结合态〉碳酸盐结合态〉有机结合态〉可交换态,且重金属在海河口附近都表现出较高的可浸取态百分含量。风险评价结果表明,重金属总量富集因子由大到小为：Pb〉Cd〉Zn〉Cr〉V〉Co〉Cu〉Ni,其中Pb、Cd和Zn的富集因子均大于1,说明其有污染,但渤海湾沉积物总体质量良好,潜在生态风险较低。从重金属形态角度评价,V和Cr无污染,Zn、Co、Cu、Ni和Pb在湾内及湾外均有不同程度的污染,而Pb的污染最为严重。