Experimental modeling of the immobilization of heavy metals at the carbonate adsorption–precipitation geochemical barrier

Experimental data obtained on the adsorption–precipitation immobilization of heavy metals (Cu, Zn, Pb, Cd, Co, and Ni) from acidic and neutral solutions by calcite and dolomite demonstrate that interaction of solutions of heavy metals with these minerals at pH > 7.8–8.1 leads to a significant decrease in the concentrations of the metals because of the crystallization of carbonates of these metals. Except Pb, which is equally removed from solutions by both minerals, the immobilization efficiency of the metals on dolomite is greater than on calculate at the same pH. Residual Zn, Cd, Co, and Ni concentrations are immobilized by chemosorption, which is the most efficient for Cd and less significant for Co, Ni, and Zn. It is proved that artificial geochemical barriers on the basis of carbonate rocks can be efficiently applied to protect environment from contamination with heavy metals.     

重金属污染的菊芋茎秆沼气化性能及蓄积重金属的归趋

利用菊芋(Helianthus tuberosus)进行重金属污染土壤修复会产生大量秸秆废弃物,通过厌氧消化将其转化为沼气,是其资源化利用途径之一。为了评估该处置技术的环境风险,实验以重金属污染土壤种植的菊芋茎秆为对象开展厌氧消化研究,对其产气性能、重金属形态变化、可迁移能力及生物有效性进行评估。结果表明,菊芋秸秆中茎主要重金属(Cu,Zn,Pb,Cr,Cd)含量为5.69×10^-6,19.19×10^-6,0.23×10^-6,0.33×10^-6,0.50×10^-6,叶中的含量分别为9.11×10^-6,23.83×10^-6,0.57×10^-6,0.43×10^-6,0.48×10^-6相对与根与块茎较较高;菊芋秸秆厌氧发酵总产气量为206.58 ml·g^-1 TS,显示产气潜力良好;厌氧消化后,Cu,Pb和Cr的重金属可迁徙因子值低,相对比较稳定,迁移能力较弱。Cr和Cd的生物可利用度减小,其中Cr大幅度减小了41.54%,Cd减小了12.30%,说明厌氧消化能有效降低Cr和Cd的生物可利用度,减小对环境的危害。但Pb的生物有效性大幅度上升,应在沼渣管控环节关注。     

The biogeochemistry of heavy metals in polluted lakes and streams at Flin Flon,Canada, and a proposed method for limiting heavy-metal pollution of natural waters

The biogeochemistry of Zn, Cd, Cu, Hg, and Fe in lakes and streams polluted by mine and smelter wastes emitted at Flin Flon, Canada, was investigated. In Schist Lake, a repository for both tailings-pond drainage and sewage, green algal blooms generated by nutrients from sewage promote entrapment of metals in sediments by (1) accumulation of metals from solution by algal seston, with preferential uptake of Zn, the most abundant metal, followed by sinking of the seston; and (2) production of H₂S during decomposition of dead algae, resulting in sulfide precipitation. Metals are partially resolubilized from seston as it decomposes while sinking. Preferential retention of Cu by sinking seston and by mud promotes Cu enrichment in the mud but the Cu/Zn ratio of mud varies with the Cu/Zn ratio of surface water seston. In bottom muds, partitioning of a metal between sulfide and organic matter is strongly dependent on the stability of the metal sulfide as measured by its standard entropy, the proportion of sulfide-bound metal decreasing in the order Hg>Cd>Cu>Fe>Zn. When sulfide-rich muds were heated under helium, x-ray diffraction revealed abundant well-crystallized ZnS (sphalerite) containing Cd, Hg, and Fe; only poorly crystallized traces of the mineral were detected in unheated mud, however. Cu sulfide failed to crystallize, suggesting interference by sorbed impurities. Metals were concentrated in H₂S-rich muds and extraction of muds with various solvents and by electrodialysis showed that sulfide was much more effective than organic matter in suppressing remobilization of metals. Remobilized Cu is probably bound to organic complexing agents. Some extractable complexing agents bind Cu preferentially with respect to Zn and Cd but others preferentially bind Zn and Cd; the complexes, being stable in the presence of free sulfide, may cause some release of metals from sulfide-rich muds in nature. These results indicate that introduction of sewage together with heavy-metal effluents into settling ponds could be an effective and economic method for limiting heavy-metal pollution of natural waters.     

Effect of citric acid on phytoextraction and antioxidative defense in <Emphasis Type="Italic">Solanum nigrum</Emphasis> L. as a hyperaccumulator under Cd and Pb combined pollution

The impact of citric acid on the ability of Solanum nigrum L. to accumulate heavy metals and on its antioxidant enzyme activity were investigated to further elucidate the effect of chelation on the heavy metal uptake and antioxidative defense in plants under conditions of heavy metal pollution. In the presence of multiple metal contaminants (Cd and Pb), citric acid treatment can significantly enhance the Cd (10–30%) and Pb (10–20%) accumulation in S. nigrum when compared to non-citric acid-treated controls; with this enhanced accumulation, S. nigrum becomes a hyperaccumulator. However, citric acid treatment only slightly influences on the increase of S. nigrum biomass. Furthermore, the combined stress of Pb and Cd resulted in a decrease in S. nigrum photorespiration; the rate of carbon dioxide fixation was restored with the application of citric acid. In addition, the presence of Cd and Pb in the soil led to disturbances in the antioxidative responses of S. nigrum; endogenous superoxide dismutase activity was approximately 3–4 times higher in the leaves than in the roots, and guaiacol peroxidase activity in the leaves was only slightly affected. It was also observed that CA increased the malondialdehyde content and total acid soluble thiol content in the presence of elevated Cd and Pb concentrations in the soil. Moreover, the combined stress of Cd and Pb resulted in progressive decrease in total glutathione and significant increase in root phytochelatins as the heavy metal concentration increased. The application of citric acid improved the mechanisms of antioxidative response and phytoextraction in S. nigrum; this improvement resulted from an increase in the solubility of heavy metals in the soil, which alleviated the metal toxicity. Therefore, citric acid could be involved in the expression of specific proteins or defense-related enzymes.     

Anthropogenic influences on toxic metals in water and sediment samples collected from industrially polluted Cuddalore coast,Southeast coast of India

The present study was carried out to investigate the impact of anthropogenic influences on Cuddalore coast, Southeast coast of India, with regard to physicochemical parameters and heavy metal concentration in the surface water and sediment samples of the study area. The samples were collected in different seasons of the year (January–December 2010) and analysed for physicochemical parameters (Temperature, pH, salinity, nitrate, nitrite, ammonia, phosphate and silicate) and heavy metals (Cd, Cu, Pb and Zn) using standard methods. Results showed that physicochemical characteristics and heavy metals concentration in the samples of the study area were varied seasonally and spatially. The concentrations of heavy metals in water and sediment samples of the study area were higher in the monsoon season compared with those of other seasons. The heavy metal concentration in collected samples was found to be above WHO standards. The order of heavy metals in water and sediment samples was Pb > Cu > Cd > Zn. The heavy metal data were analysed through widely using multivariate statistical methods including principle component analysis (PCA) and cluster analysis (CA). CA classified the sampling sites into three clusters based on contamination sources and season. The PCA revealed that the season has a huge impact on the levels, types and distribution of metals found in water and sediment samples. The study also shows the main basis of heavy metals pollution at Cuddalore coast is land based anthropogenic inputs as a result of discharging of waste from industries, municipal, agricultural activities and sewage into estuarine regions, which carries the wastes into coastal area during tidal action. Statistical analyses and experimental data revealed that the Cuddalore coast may cause health risk to the recreational users and fisher folk, ultimately warrants environmental quality management to control heavy metal contamination.     

长江口海域表层沉积物重金属元素赋存形态特征

通过长江河口地区水下表层沉积物样品多种化学元素的赋存形态分析测试数据,综合分析重金属元素的赋存形态特征。研究结果显示：镉、汞、铅残渣态所占比例均小于50%,锌、砷、铬、铜、镍残渣态占比均大于50%;8个元素的残渣态与全量呈显著正相关关系。沉积环境和沉积物粒径对重金属元素赋存形态具有重要影响。沉积物的物质来源、矿物组成特征、水动力作用与沉积物粒度和物理化学条件等是长江口地区表层沉积物重金属元素赋存形态的主要控制因素。     

Heavy metal exposure from co-processing of hazardous wastes for cement production and associated human risk assessment

This study was carried out to determine the concentration of heavy metals (Cd, Ni, Pb, Cr, Ni and Zn) in ordinary Portland cement (OPC) produced from the co-processing with hazardous waste in comparison with OPC produced using natural raw materials. The results showed that the concentration of heavy metals in cement produced from natural raw material was in the order of Zn > Pb > Cr > Ni > Cu > Cd. Zn and Cd were the highest and the lowest concentrations, respectively, in cements produced from the co-processing activity. The difference between heavy metals concentrations in OPC produced with and without co-processing was found to be statistically significant. The concentration of heavy metals in the cement produced is generally factory dependent. The human risk assessment associated with the heavy metals for non-carcinogenic and carcinogenic risks has been evaluated. The calculated hazard index (HI) and total lifetime cancer risks (LCR) were lower than the acceptable threshold reference values, HI < 1 and LCR < 1 × 10^?4, respectively. Thus, it is anticipated that there is no potential of non-carcinogenic and carcinogenic risks for both adult and children. However, the findings indicated that there is a need for regulatory monitoring. The exposure pathway for both non-carcinogenic and carcinogenic risks are both in the order of ingestion > dermal > inhalation.     

干旱区绿洲土壤共存重金属元素形态变化及生物有效性实验分析——以Cd、Zn、Ni元素为例

采用盆栽试验,初步研究了干旱区绿洲土壤—胡萝卜系统中镉、锌、镍3种重金属的形态变化特征及其生物有效性问题。结果表明:供试绿洲土壤原状土中,Cd、Zn、Ni均以稳定的残渣态形式存在,而处理土壤中重金属被钝化的量有限,Cd的存在形式主要以碳酸盐态为主,Zn、Ni则主要以铁锰氧化态为主;3种元素的活性大小依次为Cd>Ni>Zn。根据回归分析,元素Zn对胡萝卜块茎和茎叶吸收Zn量贡献最大的分别是Zn的碳酸盐结合态和铁锰氧化态;元素Ni对胡萝卜各部位吸收贡献最大的均为Ni的铁锰氧化态。     

全国土壤污染状况详查重金属元素可提取态提取试剂的选择

土壤重金属元素可提取态是衡量其生物有效性的重要指标,但其含量随着土壤酸碱性等环境条件的变化而改变,在提取土壤重金属元素可提取态时,不可避免地面临着提取剂与提取方法的选择。中国有关土壤重金属元素可提取态的标准分析方法或技术规范涉及的提取剂多达7种(pH=5.8盐酸溶液、0.1mol/L盐酸溶液、0.43±0.02mol/L硝酸溶液、0.11mol/L乙酸溶液、1mol/L硝酸铵溶液、0.005mol/L DTPA浸提剂、0.01mol/L氯化钙溶液),不同学者对不同提取剂有不同的研究结论,对于通用提取剂的系统研究未见报道。本文选择代表性农耕土壤样品,采用以上7种提取剂提取其中8种重金属元素(镉镍铜锌铬铅砷汞),电感耦合等离子体质谱法(ICP-MS)测定镉铬铜铅锌镍含量,原子荧光光谱法(AFS)测定砷和汞含量,对比了7种提取剂对各重金属元素的提取率,并研究了土壤酸碱性质对重金属元素提取率的影响。结果表明：(1)稀酸溶液对土壤重金属元素的提取率较高,且与土壤的酸碱性无关;(2) 1mol/L硝酸铵溶液虽然对镉的提取能力表征了镉在酸性土壤中的活性远大于碱性土壤的特点,但其对碱性土壤中铅的提取率...     

北京平原区两年内土壤中五种重金属元素化学形态变化及生物有效性

为了监测北京市平原区2015年和2016年土壤中5种重金属As、Cd、Hg、Pb、Zn化学形态的变化趋势,运用Tessier连续提取法对土壤重金属进行了形态分析,并对影响重金属元素生物有效性的因素进行研究。结果表明,2年内研究区表层土壤重金属元素的形态变化微弱,有效态含量以Cd元素最高,达到45.67%,故潜在生态危害性最大;其次为Zn元素,达12.16%,其中碳酸盐结合态占比虽大,但由于研究区土壤呈偏碱性,Zn元素的迁移能力较弱,潜在危害性较小;As、Hg、Pb均以难迁移态存在,故潜在危害性也较小。土壤重金属元素的生物活性系数及迁移系数分别为:CdZnPbAsHg和CdAsZnPb=Hg,其中Cd元素2年的生物活性系数和迁移系数最高,展现出较强的生物活性和迁移能力,其余重金属元素的活性系数和迁移系数较低,潜在危害性较弱。影响重金属元素生物有效性的因素较复杂,以重金属元素全量为主,p H、有机质、CEC等理化性质次之。     

滇西沘江流域水体中重金属元素的地球化学特征

通过测定流经兰坪金顸铅锌矿区的沘江水体中Pb、Zn、Cd、As的含量和底泥中重金属元素的化学形态的含量,分析了重金属元素的分布和化学形态的变化。结果表明,沘江水遭到了Cd污染,底泥已经成为重金属元素的蓄积库,以国家土壤环境质量标准（Ⅲ级）衡量,Pb、Zn、Cd和舡分别超标3．4倍、15．8倍、106倍和2．6倍。沘江水中重金属元素含量的峰值在矿山附近的下游,而底泥中重金属元素的峰值在矿山下游30-50km的地方,矿业活动、水流变缓、pH等水体环境条件的变化都能影响水和底泥中重金属元素的含量。底泥中的Pb以碳酸盐结合态为主,Zn和Cd以铁锰氧化物结合态为主,而As以残渣态为主。Pb、Cd、Zn三种元素的环境有效态含量比较高,对沘江流域生态环境具有潜在的巨大的危害。     

Estimates of potential nitrate reductase activity in sediments: comparisons of two incubation methods and four inhibitors

Sediment samples, collected from a large shallow lake, Taihu, China, were incubated in two conditions (with and without air extraction) with regard to four soil enzyme’s inhibitors (dry and moist heat sterilizations, chloramphenicol and toluene) to estimate the potential nitrate reductase (Nar) activities. The objectives of paper were to define (1) whether to exclude air from the mixture of sediment and substrate solution prior to incubation was necessary, and (2) the efficacy of four inhibitors when assaying the enzyme. No significant difference between two incubation methods was found (P < 0.05), indicating that it is not necessary for estimating the potential Nar activity in the sediment to construct an initial anaerobic condition by air extractions prior to incubation. Toluene (1.0 mL/g sediment) and dry heat sterilization effectively and persistently inhibit the reduction of nitrate to nitrite during the incubation of 42 h. The authors concluded that both should be used as preferred inhibitors. In contrast, chloramphenicol (30 μg/g sediment) and moist heat sterilization inhibitors restrained nitrate reduction for <24 h only. In addition, it was found that no nitrite produced was substantially reduced in 24 h. Therefore, it should be needless for potential Nar activity estimation in the sediment to add 2,4-dinitrophenol to inhibit nitrite reductase.     

Biological removal of cadmium by Alcaligenes eutrophus CH34

Some bacteria like the heavy metal resistant Alcaligenes eutrophos CH34strains are able to promote biomineralization, being the biologically induced crystallization of heavy metals. In the presence of heavy metals, this strain may create an alkaline environment in the periplasmic space and outer cell environment appropriate induction of heavy metals resistance mechanisms. In such an environment metal hydroxides are formed together with metal bicarbonates resulting from the carbonates production by the cell. Also metals bind to out cell membrane proteins and the metal hydroxides and bicarbonates precipitate around these nucleation foci inducing further metal crystallization. A pilot-plant was set up in which Alcaligenes eutrophus CH34 were inoculated and reproduced in a composite membrane, based on polysulfone. The membrane is casted on a polyester support. The biological membrane was in continuous contact with nutrients from inside and the other side was in contact with wastewater flow containing 120-mg/l cadmium. Nutrients are used for growth and reproduction of bacteria and for development of bacteria resistance agents against heavy metals. At the effluent side immobilized bacteria induce metal precipitation and metal crystals. A column, which was in continuous contact with treated effluent, was continuously filled with glass bends to which the metal crystals bind and grow. The efficiency for Cd removal was over 99 percent. Cd removal could be recovered from the recuperation column by acid treatment without damaging the bacteria.     

Chromium-induced depression of <Superscript>15</Superscript>N content and nitrate reductase activity in rice seedlings

Hydroponic experiments were conducted to investigate the influence of chromium (Cr) exposure on assimilation of ¹⁵N-labeled nitrate in rice (Oryza sativa L. cv. XZX 45) seedlings. Results showed that exposure of young seedlings to both Cr compounds led to a linear decrease in relative growth rate, nitrate reductase (NR) activity and tissue ¹⁵N accumulation though responses differed between the two Cr variants, in which potassium chromate [Cr(VI)] caused more severe effects than chromium chloride [Cr(III)]. Analysis of subcellular distribution of Cr showed that Cr deposition in cell wall was the highest in tissues of rice seedlings exposed to Cr(III), whereas the largest deposition of Cr in the roots was associated with cytosol in the Cr(VI) treatments. Analysis of a partial correlation between tissue fractions of Cr, NR activity and ¹⁵N content revealed that depression of NR activity in plant materials of rice seedlings exposed to Cr(III) was mainly associated with a decrease in ¹⁵N accumulation, whereas inhibition of NR activity from exposure of plants to Cr(VI) was most likely due to the presence of Cr in cytosol. Information collected here indicated that mechanisms of transport, subcellular distribution and phytotoxicity of the two Cr compounds were different in rice seedlings.     

干旱区绿洲土壤共存重金属元素形态变化及生物有效性实验分析

采用盆栽试验,初步研究了干旱区绿洲土壤—胡萝卜系统中镉、锌、镍3种重金属的形态变化特征及其生物有效性问题。结果表明：供试绿洲土壤原状土中,Cd、Zn、Ni均以稳定的残渣态形式存在,而处理土壤中重金属被钝化的量有限,Cd的存在形式主要以碳酸盐态为主,Zn、Ni则主要以铁锰氧化态为主;3种元素的活性大小依次为Cd＞Ni＞Zn。根据回归分析,元素Zn对胡萝卜块茎和茎叶吸收Zn量贡献最大的分别是Zn的碳酸盐结合态和铁锰氧化态;元素Ni对胡萝卜各部位吸收贡献最大的均为Ni的铁锰氧化态。     

小秦岭金矿区土壤重金属生物有效性与影响因素

土壤中重金属生物有效性与影响因素分析是土壤重金属风险管控的关键问题。通过实地调查、现场采样、实验测试、综合分析等方法,分析了研究区100km2内Hg、Pb、Cd、Cr、As、Cu、Zn七种重金属元素的有效态含量特征,研究了这些重金属有效态含量之间、有效态含量与全量、有效态与土壤pH、有机质含量、粒度等基本理化参数之间的相关性,分析了重金属污染来源。结果表明,土壤中Hg、Pb、Cd、Cr、As、Cu、Zn七种重金属有效态的平均含量分别为2.29mg/kg、594mg/kg、2.52mg/kg、6.30mg/kg、2.16mg/kg、48.14mg/kg、50.21mg/kg,其变异系数大小为:HgPbCuZnCdAsCr。Hg的变异系数最大,是由于金矿选矿活动采用混汞法提金排放的尾矿堆(库)分布不均。Hg、Pb、Cd、Cu、Zn有效态量与全量之间均存在显著的相关性;土壤有机质与重金属有效态之间存在显著的相关性;土壤pH与有效态重金属之间存在显著的负相关性;土壤粒度对重金属有效态的累积影响不明显。     

Distribution and speciation of heavy metals and their sources in Kumho River sediment,Korea

The interaction between heavy metals and river sediment is very important because river sediment is the sink for heavy metals introduced into a river and it can be a potential source of pollutants when environmental conditions change. The Kumho River, the main tributaries of the Nakdong River in Korea, can be one of the interesting research targets in this respect, because it runs through different geologic terrains with different land use characteristics in spite of its short length. Various approaches were used, including mineralogical, geochemical, and statistical analyses to investigate the distribution and behavior of heavy metals in the sediments and their sources. The effect of geological factor on the distribution of these metals was also studied. No noticeable changes in the species or relative amounts of minerals were observed by quantitative X-ray diffraction in the sediments at different stations along the river. Only illite showed a significant correlation with concentrations of heavy metals in the sediments. Based on an average heavy metal concentration (the average concentrations of Cd, Co, Cr, Cu, Ni, Pb, and Zn were 1.67, 20.9, 99.7, 125, 97.6, 149, 298 ppm, respectively), the sediments of the Kumho River were classified as heavily polluted according to EPA guidelines. The concentrations of heavy metals in the sediments were as follows: Zn > Pb > Cu > Ni > Cr > Co > Cd. In contrast, contamination levels based on the average I _geo (index of geoaccumulation) values were as follows: Pb > Cd > Zn > Cu > Co = Cr > Ni. The concentrations of heavy metals increased downstream (with the exception of Cd and Pb) and were highest near the industrial area, indicating that industrial activity is the main factor in increasing the concentrations of most heavy metals at downstream stations. Sequential extraction results, which showed increased heavy metal fractions bound to Fe/Mn oxides at the downstream stations, confirmed anthropogenic pollution. The toxicity of heavy metals such as Ni, Cu, and Zn, represented by the exchangeable fraction and the fraction bound to carbonate, also increased at the downstream stations near the industrial complexes. Statistical analysis showed that Pb and Cd, the concentrations of which were relatively high at upstream stations, were not correlated with other heavy metals, indicating other possible sources such as mining activity.     

武水河上游区域土壤重金属污染风险及来源分析

生态功能区在涵养水源、保持水土、维系生物多样性等方面具有重要的作用。本文以位于南岭生态功能区的流域——武水流域为研究对象,采集流域上游交通运输用地、采矿用地、工业用地、耕地及林地5种土地利用类型土壤样品,分析7种重金属Cd、As、Cu、Hg、Ni、Pb、Zn的含量特征,采用内梅罗综合污染指数评价重金属污染的程度,Hakanson潜在生态风险指数法评价土壤重金属潜在生态风险,并应用主成分分析法探究重金属污染的来源。研究结果显示,武水河上游地区土壤重金属Cd、As、Cu、Hg、Ni、Pb、Zn平均含量分别为1.28、72.44、54.62、0.27、68.32、72.29和158.42mg/kg,均高于土壤背景值,其中采矿用地土壤重金含量除Hg外均高于其他类型土壤。均值状态下土壤中Cd和As单因子污染指数分别为5.07、3.25,其中采矿用地中Cd单因子污染指数可达13.59;土壤重金属综合污染指数表明,采矿用地污染最为严重,其次是工业用地,林地呈安全状态。潜在生态危害指数评价结果显示,采矿用地和工业用地达到了强生态危害,其他类型土壤为轻微生态危害,而采矿用地土壤中Cd达到极强生态危害,As为强生态危害。土壤重金属来源研究结果表明,As、Cd、Cu和Zn来源于矿山开采及工业活动,Ni和Hg主要来源于成土母质,Pb则来源于交通运输。研究认为:武水流域上游区土壤重金属污染情况较为严重,Cd和As是区内主要的风险因子,主要来源于矿山开采以及工业活动。     

Bioaccumulation of heavy metals in organs of fresh water fish Cyprinus carpio (Common carp)

The objective of the present study is to determine the bioaccumulation of heavy metals in various organs of the fresh water fish exposed to heavy metal contaminated water system. The experimental fish was exposed to Cr, Ni, Cd and Pb at sublethal concentrations for periods of 32 days. The elements Cd, Pb, Ni and Cr were assayed using Shimadzu AA 6200 atomic absorption spectrophotometery and the results were given as μ/g dry wt. The accumulation of heavy metal gradually increases in liver during the heavy metal exposure period. All the results were statistically significant at p < 0.001. The order of heavy metal accumulation in the gills and liver was Cd > Pb > Ni > Cr and Pb > Cd > Ni > Cr. Similarly, in case of kidney and flesh tissues, the order was Pb > Cd > Cr > Ni and Pb > Cr > Cd > Ni. In all heavy metals, the bioaccumulation of lead and cadmium proportion was significantly increased in the tissues of Cyprinus carpio (Common carp).     

珠江三角洲污灌区地下水重金属含量及其相互关系

为了解污灌区地下水重金属含量特征,采集地表水样5组、地下水样14组进行化学组分定量分析。结果表明：污灌区地下水8种重金属元素中,仅有Ni和As两种元素超标,超标率分别为14.3％和42.9％。8种重金属含量在污灌区地表水、工厂废水以及地下水中存在明显的对应关系。Ni、Zn、Se、Cd这4种元素间存在显著或极显著的正相关关系,Cu与Pb和Cd分别呈极显著和显著的正相关关系,Cr仅与Ni呈显著的正相关关系,As与其它7种元素的相关性均不明显。聚类分析结果显示8种重金属可分为4类：Pb和Cu一类,Se、Cd、Ni、Zn一类,Cr和As均单独一类。Pb和Cu与Fe的相似性最好,Se、Cd、Ni、Zn与Mg²⁺存在较好的相似性,Cr与HCO^－₃的相似性最好,As与SO^2－₄存在一定的相似性。