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).     

湖南洞庭湖地区土壤-作物系统铅含量及其影响因素

以湖南洞庭湖地区为研究区域,探讨了土壤有机质、pH值、P、N对Pb在土壤-作物系统中迁移的影响,研究了Pb、Cd复合污染对水稻Pb、Cd富集的作用。相关分析结果表明:随土壤有机质含量的增加,离子交换态Pb含量减少,但通过转化可以被植物吸收利用的有机质的结合态Pb含量增加,进而增加了水稻对土壤Pb的吸收量;土壤为中性偏碱性时,土壤中Pb的活性和水稻Pb的富集能力均较酸性土壤中有所降低;在土壤中增施氮肥和磷肥可降低土壤中离子交换态Pb的含量,减少水稻对Pb的吸收。因此,土壤有机质、pH值、P、N是影响水稻Pb含量及土壤Pb活性的重要因素。Pb-Cd复合污染研究结果表明:土壤中同时存在Pb、Cd时,Pb元素的存在促进了水稻对Cd元素的吸收,而Cd却抑制了水稻对Pb的吸收。     

影响向海湿地草根层土壤吸附铅、镉能力的因素

利用向海湿地采集的草根层土壤进行吸附铅、镉的热力学实验,结果表明草根层土壤吸附铅、镉的过程符合Langmuir和Freundlich等温吸附曲线(n=8,p=0.01).吸附铅、镉存在干扰吸附现象,吸附铅的能力约是吸附镉的能力的3倍.而且草根层土壤吸附铅、镉的最大吸附量与土壤中的有机质和铁、锰氧化物含量存在着正相关性.土壤的理化性质是影响土壤吸附铅、镉能力的内在主要因素;pH等是影响草根层土壤吸附铅、镉能力的外部主要因素.     

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.     

山东烟台环境介质中重金属元素富集特征及与酸化土壤的关系

利用山东省烟台市生态地球化学调查及相关专题研究所取得的分析测试数据,通过高灵敏度的识别系统和多参数地球化学评价体系的建立,揭示了在重金属污染区内酸化的土壤环境中Cd、Hg、Pb、As等重金属元素活化迁移的地球化学机制、影响因素,以及浅层地下水和玉米等主要粮食作物籽实中重金属超标的原因及生态危害。与全国土壤基准值和背景值对比,研究区内Cd、Cr、Ni、Pb等元素的基准值相对偏高,Cd、Cr、Pb、Cu、Ni元素的背景值相对较高。As、Cd、Cr、Ni、Hg、Pb等存在于Ⅲ级及Ⅲ类以上土壤,是主要致污因子。典型金矿污染区内浅层地下水和玉米籽实中均检出超标重金属元素,影响浅层地下水环境质量的主要指标是Pb。达到Ⅲ类及以上水质标准的采样点数占研究区总采样点数的3.47%;玉米中的Cd含量相对较高。表层酸性、弱酸性土壤占土壤总面积的55.29%,土壤酸化趋势明显。随着土壤酸化程度的加深和范围扩大,导致土壤耕作层可给性营养元素的损失及某些毒性元素(Cd、Pb等)的释出和活化,提高了土壤中主要污染因子Cd、Hg、Ni、Pb、As等重金属的活化迁移能力;富含有机质的土壤中有利于对Cu、Zn、Pb、Cd的吸收,固重金属元素于土壤中,降低了土壤重金属污染的环境风险水平。研究结果为土壤修复、降低土壤重金属毒性提供了重要的科学依据。     

不同环境条件对固定化细菌吸附低浓度Cd2+规律的影响

采用固定化技术将吸附重金属能力较强的优势细菌固定,然后将其对Cd²⁺进行吸附规律研究。结果表明：固定化细菌对Cd²⁺吸附是动态过程,120 min达到吸附平衡;随着重金属Cd²⁺浓度的增加,固定化细菌对其吸附量呈线性增加,而随着离子强度的增加,固定化细菌对其吸附量呈线性降低;当吸附体系pH=6时吸附量最大;环境温度对固定化细菌吸附影响不显著;共存Pb²⁺降低了固定化细菌对Cd²⁺的吸附量。     

Effects of Pb^2＋, Cd^2＋ and Cu^2＋ on the Aqueous Zn^2＋ Sorption by Hydroxyapatite

In this paper, the behaviors of aqueous zinc sorption by hydroxyapatite in the co-existence of Pb^2＋, Cd^2＋ and Cu^2＋ are investigated, the effects of Pb^2＋, Cd^2＋ and Cu^2＋ on the sorption of Zn^2＋ are discussed, and the hydroxyapatite sorption capabilities for Pb^2＋, Cd^2＋, Cu^2＋ and Zn^2＋ are compared. The experimental results show that the Zn^2＋ removal efficiency decreases gradually with the increase of the Cd^2＋ concentration of the solution, and there is no sorption preference between Cd^2＋ and Zn^2＋. On the other hand, the Zn^2＋ removal efficiency rapidly decreases rapidly with the increase of the Cu^2＋ concentration of the solution, and there is a clear sorption preference between Cu^2＋ and Zn^2＋. It is noticed that the Zn^2＋ removal efficiency is hardly changed with the variance of Pb^2＋ concentration because the removal mechanisms for these two ions are totally different. It is concluded that the adsorption affinities of the heavy metals for the hydroxyapatite follows this sequence： pb^2＋〉 Cu^2＋〉 Cd^2＋〉 Zn^2＋.     

甘肃省白银市区土壤环境质量评价

对白银市区土壤中Cu、Pb、Zn、Cd、Hg的分布、存在形式和在水体中的含量进行分析,认为该区土壤、水体已受到Cu、Pb、Zn、Cd、Hg等重金属污染.按国家土壤环境质量标准,白银市土壤中Cd的环境质量均未达到Ⅰ级标准,Ⅲ级、Ⅳ级污染面积占研究区面积的82.39％,污染比较严重;Hg、Pb、Zn、Cu的Ⅲ级及其以上污染区面积分别占研究区的7.35％、5.59％、14.67％、5.71％.通过2000年与2007年白银市土壤重金属元素背景值对比发现,Cu、Pb、Zn、Cd、Hg的污染增速明显,并有逐渐扩大的趋势.对Cu、Pb、Zn、Cd、Hg的成因来源进行了初步探讨,认为有色金属冶炼、加工和重化工是主要污染源,其次为燃煤、生活垃圾及汽车尾气排放.     

太湖流域土壤重金属元素污染历史的重建:以Pb、Cd为例

太湖是位于长江下游的一个大型浅水湖泊,通过对4个代表太湖不同沉积环境的湖底沉积剖面的137Cs和210Pb沉积定年,重建太湖湖底沉积物和太湖来水流域土壤Cd、Pb的污染历史。结果显示:1980年以前,太湖底积物中Cd、Pb含量与流域内的自然背景含量相当,1980年以后,湖底沉积物中的Cd、Pb含量显著增高,这与我国大规模工业化进程的起始时间基本一致,推测工业化进程是湖底沉积物中Cd、Pb含量增加的主要原因。1900年以来太湖湖底沉积物中累积含有Cd和Pb分别为146t和25980t,其中苕溪来水提供的Cd和Pb分别为40t、6777t,宜溧河来水提供的Cd、Pb分别为36t、6023t,其他来水(洮、滆、运河)提供的Cd、Pb分别为71t、13179t,其他来水是太湖Cd、Pd累积的主要输入途径。Cd、Pb累积的高峰期为20世纪80—90年代,1980年以来,运河来水Cd、Pb的输出通量为28.26t、3419t;苕溪流域Cd、Pb的输出总量分别为13.70t、1585t,其中人为源的Cd、Pb为8.90t、610t,人为源输出的Cd、Pb通量占总输出量的64.96%和38.47%;宜溧河流域Cd、Pb的输出总量分别为10.09t、1063t,人为源的Cd、Pb分别6.96t和500t,人为源输出的Cd、Pb通量占总输出量的68.68%和47.08%,表明太湖流域人类活动所导致的Cd已超过自然剥蚀过程,因此削减工业化进程中的Cd、Pb排放总量,控制太湖运河来水的输出通量是改善太湖底积物Cd、Pb环境质量的关键措施。     

Cation hydrolysis and the regulation of trace metal composition in seawater

Thermodynamic calculations have been performed for cation hydrolysis, including temperatures from 2°C to the high values of significance near Mid-Oceanic Ridge Systems (MORS). Eighteen elements with wide range of residence times (t) in seawater (Mn, Th, Al, Bi, Ce, Co, Cr(III), Fe, Nd, Pb, Sc, Sm, Ag, Cd, Cu, Hg, Ni and Zn) have been considered. A model for the regulation of trace metal composition in seawater by cation hydrolytic processes, including those at MORS, is presented. Results show an increase in the abundance of neutral metal hydroxyl species with increase in temperature. During hydrothermal mixing, as the temperature increases, transformation from lower positive hydroxyl complexes to higher or neutral complexes would occur for Cd, Ce, Co, Cr(III), Cu, Mn, Nd, Ni, Pb, Sm and Zn. pH values for adsorption of the metal ion onto solid surfaces have direct relation with pH values of hydrolysis. Co, Mn and Pb could be oxidized to higher states (at Mn-oxide surfaces) that would occur even at MORS. Ce can also be oxidized at 25°C. Solubility calculations show that Al, Bi, Cr(III), Sc, Fe and Th are saturated while Ce, Nd and Sm are not with respect to their oxyhydroxide solids at their concentrations in seawater at 25°C. Cu, Hg, Ni and Zn reach saturation equilibrium at 250°C, whereas Co, Mn and Pb exhibit unsaturation. The results suggest an increase in scavenging capacity of a cation with rise in temperature.     

Competitive sorption and desorption of cadmium and lead in paddy soils of eastern China

To assess the competitive sorption and desorption of cadmium (Cd) and lead (Pb), batch equilibrium experiments were performed using single- and binary-metal solutions in surface samples of three paddy soils from eastern China. Sorption isotherms were well fitted with one-metal and competitive Langmuir equation for single- and binary-metal system, respectively. The distribution coefficient (K _d) values were K _{d single} (Pb) > K _{d binary} (Pb) > K _{d single} (Cd) > K _{d binary} (Cd), indicating that Pb was stronger sorbed by these soils than Cd in binary metal system. Soils with high pH and clay content had the greatest sorption capacity as estimated by the maximum sorption parameter (Q). The co-existence of both metals reduces their tendency of sorption, whereas Cd sorption was affected to a greater extent than that of Pb. The Langmuir binding strength parameter (b) in binary sorption system was greater than that in single sorption system for all soils (b < b ₁), indicating that competition for sorption sites promote the retention of both metals into more specific sorption sites. Sorption of Cd and Pb decreased soil pH by 1.61 U for YRS, 1.39 U for PCS, and 0.91 U for SLS. The decreases of pH in binary metal system were greater than in single-metal system for three soils. Cadmium and Pb desorption increased with increasing Cd and Pb sorption saturation for all soils; however, Cd desorption ratio in binary metal system (d _Cd*) was much greater than Pb (d _Pb*), indicating that under the competitive sorption conditions, the sorbed Cd was more readily desorbed from the soils than the sorbed Pb.     

太湖沉积物中重金属的地球化学形态及特征分析

用连续提取法分析了太湖沉积物5种重金属的地球化学形态,对地球化学形态的组成和地理特征进行了分析研究.重金属地球化学形态配分的共同特点是可交换态最低,残渣态最高.两种形态中Cd的可交换态最高,Cr的残渣态最高,可交换态最低.Cd的碳酸盐态较高,Cr的最低;Pb、Cd的Fe-Mn氧化态较高,Cu的偏低;Cu的有机态最高,Cd的最低;Zn的地球化学形态比例大都处于中间.地域上变化较大的元素是Cd和Cu,变化不明显的元素有Pb和Zn.化学成分中Fe2O3、MnO与重金属地球化学形态的相关性最好,TOC与Cu的形态相关系数最高.综合对比分析表明,太湖沉积物重金属的生物有效性以Cd为最高,其次为Pb.     

冻融作用对黑土和棕壤中Pb、Cd吸附/解吸特征的影响

冻融作用对土壤理化性质具有重要影响,进而影响了土壤中重金属迁移转化过程和环境效应。通过实验模拟研究了冻融作用对黑土和棕壤中Pb、Cd吸附/解吸特征的影响。结果表明：黑土对Pb和Cd的吸附能力大于棕壤;冻融作用降低了土壤对Pb和Cd的吸附能力,这与冻融作用改变了土壤的理化性质有关;随着Pb和Cd吸附量的增大,黑土和棕壤中Pb和Cd的解吸量和解吸率也相应增大;冻融作用促进了黑土和棕壤中Pb和Cd的解吸,并且在同一冻融条件下黑土的解吸能力小于棕壤;冻融作用使得黑土和棕壤对Pb和Cd的解吸量大于未冻融土壤,这与冻融作用使解吸溶液pH的下降幅度增大有关。冻融作用降低了土壤对Pb和Cd的固持能力,增加了土壤中Pb和Cd的生态风险。     

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。     

重金属污染物侵入对岩石力学性能影响的研究

通过抗剪强度试验、风化耐久性强度试验、耐崩解试验、点荷载试验,对受重金属污染的泥岩、页岩、砂岩的力学强度变化特性进行了研究,并根据试验结果绘制了3种岩石抗压强度与重金属含量的关系曲线,采用线性回归法分析了岩石抗压强度与重金属质量比的相关关系。研究结果表明:在岩性、含水量、试验条件等相同的条件下, 3种重金属污染岩石的力学强度都随着重金属污染物含量的增加而减小; 重金属污染的泥岩、砂岩和页岩的单轴抗压强度与重金属质量比关系分别呈幂函数(泥岩、砂岩)、对数函数(页岩)关系,关系分化度为较显著-显著负相关。根据Weibull分布定律与对流-扩散特性建立了重金属污染物侵入与延伸性能方程,并对泥岩试验结果进行了计算,绘制了侵入性能、延伸性能与时间的关系曲线。结果表明: 4种金属元素在泥岩中平均侵入性能与延伸性能的大小顺序为Cd2+ Pb2+ Cu2+ Zn2+,且元素活性越大,侵入能力与延伸能力越强,侵入性能随着时间变化而逐渐减小,延伸性能随时间变化而逐渐增加。     

Heavy metal pollution of coastal river sediments, north-eastern New South Wales, Australia: lead isotope and chemical evidence

 Heavy metal and metalloid concentrations within stream-estuary sediments (<180-μm size fraction) in north-eastern New South Wales largely represent natural background values. However, element concentrations (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Zn) of Hunter River sediments within the heavily industrialized and urbanized Newcastle region exceed upstream background values by up to one order of magnitude. High element concentrations have been found within sediments of the Newcastle Harbour and Throsby Creek which drains into urbanized and light industry areas. Observed Pb enrichments and low ²⁰⁸Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁶Pb/²⁰⁴Pb ratios are likely caused by atmospheric deposition of Pb additives from petrol and subsequent Pb transport by road run-off waters into the local drainage system. Sediments of the Richmond River and lower Manning, Macleay, Clarence, Brunswick and Tweed River generally display no evidence for anthropogenic heavy metal and metalloid contamination (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Zn). However, the rivers and their tributaries possess localized sedimentary traps with elevated heavy metal concentrations (Cu, Pb, Zn). Lead isotope data indicate that anthropogenic Pb provides a detectable contribution to investigated sediments. Such contributions are evident at sample sites close to sewage outlets and in the vicinity of the Pacific Highway. In addition, As concentrations of Richmond River sediments gradually increase downstream. This geochemical trend may be the result of As mobilization from numerous cattle-dip sites within the region into the drainage system and subsequent accumulation of As in downstream river and estuary sediments. Received: 5 September 1997 · Accepted: 4 November 1997     

Trace metal in beach sediments of Velanganni Coast,South India: application of autoclave leach method

The concentration of trace metals like Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were studied in beach and estuarine sediments of the Velanganni Coast, South East coast of India to understand metal pollution due to urbanization/industrialization. This area was affected by the urbanization activity like untreated effluent discharge, transportation and incineration of solid waste, etc. In this context, quality of the sediments was evaluated based on the enrichment factor, geo-accumulation index (Igeo), pollution load index, and sediment quality guidelines. Furthermore, correlation matrix and principal compound analyses have been performed with SPSS 7.5 statistical software. The result illustrated that the metal enrichment is in the following order: Cd > Cr > Ni > Zn > Pb > Mn > Cu. The level of Igeo suggests that Cd has moderately polluted the sediment class. Similarly, principal component analysis showed that Cd and Pb accounted for the anthropogenic pollution, but Pb inferred as its tracers level. The results strongly indicate anthropogenic sources for moderate input of Cd contamination in to Velanganni coastal sediments.     

改性氢氧化镁对地下水中铅镉的稳定化性能研究

为研究OH-缓释剂对铅、镉污染地下水修复的可行性,通过室内实验制备改性氢氧化镁,并对其去除地下水中Pb和Cd的性能进行研究。实验结果表明,重金属的稳定化机理主要为沉淀反应。在去除单一重金属(Pb或Cd)实验中,Pb和Cd的去除率都可达到99%以上,反应符合一级反应动力学,反应速率常数分别为0.173 7 min-1和0.003 7 min-1。改性氢氧化镁在处理Pb和Cd的复合污染时Pb优先于Cd反应,Pb的存在会对Cd的沉淀起到抑制作用。     

Assessment of the physicochemical parameters and heavy metals toxicity of leachates from municipal solid waste open dumpsite

Heavy metals and physicochemical characteristics of the different sites of the municipal solid waste dumpsite at Olusosun Landfill, Lagos, Nigeria, were investigated. The dormant site of the landfill has the potential of being a source of immediate environmental risk compared to the active and abandoned site, with the active site exhibiting tendency to be a likely source of Pb, Cd and Zn pollution. Zn was the most abundant metal in the area (0.264–0.947 mg/L) while Cd concentration was the lowest (0.001–0.022 mg/L). Pb, Cd, Zn were from anthropogenic sources and correlated significantly with chemical oxygen demand and oil and grease. Cu and Cr were more abundant in the dormant site and are attached to the solids as indicated by their significant correlation with TS and SS. The physicochemical characteristic of the leachate from the landfill indicate that they were more alkaline in nature, with TA range of 2354 to 7946 mg/L while the chemical oxygen demand values was also high 518.14 to 725.01 mg/L. The comparative analysis of the dormant site with other dormant site reveal a moderate concentration of the parameters measured but could contaminate the neighboring groundwater if not checked.     

长江源区Cd地球化学省与主要水系的Cd输出通量

中国正在进行的多目标区域地球化学调查成果显示,长江流域存在贯穿全流域的Cd地球化学异常,因此研究该异常的成因及查明长江主要支流Cd的输出通量已成为科学研究的焦点。长江源区水系包括通天河干流及沱沱河、楚玛尔河、尕尔曲、布曲、当曲、口前曲、聂恰曲支流。采用1样/km2的密度采集水系沉积物样品对长江源区进行地球化学填图,在沱沱河—尕尔曲和扎曲—聂恰曲流域分别圈出规模巨大的Cd、Pb、As地球化学省,其他地区Cd、As、Pb均为正常的地球化学背景区。研究发现沱沱河—尕尔曲Cd、Pb、As地球化学省内岩石中Cd、Pb、As含量明显高于土壤和水系沉积物,表明岩石在风化形成土壤和水系沉积物过程中已向水体释放了大量的Cd、Pb、As。通天河干流原水中Cd、Pb、As的平均质量浓度分别为0.144、17.62、2.59μg/L,沱沱河原水中Cd、Pb、As的质量浓度为0.187、19.89、2.33μg/L,聂恰曲原水中Cd、Pb、As的质量浓度为0.144、6.37、2.33μg/L,较其他支流中的含量高近1个数量级,表明源区原水中Cd、Pb、As含量主要受地质背景控制。年输出通量计算显示,由沱沱河输入到通天河中的Cd、Pb、As年通量分别为0.155、16.47和1.93t/a,楚玛尔河输入到通天河中的Cd、Pb、As年通量分别为0.015、0.77、0.35t/a,尕尔曲—布曲输入到通天河中的Cd、Pb、As年通量分别为0.095、10.31、2.72t/a;由通天河输入到金沙江的Cd、Pb、As年通量分别为2.48、290.7、42.3t/a,表明长江源区Cd地球化学省是长江沿江Cd地球化学异常带形成的重要物质来源。对原水和清水(过0.45μm滤膜)中Cd、As、Pb分析显示,长江源区水体中Cd、Pb主要以悬浮物形式迁移,As则以可溶态形式迁移。