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1.
河口污染沉积物中重金属释放与迁移的围隔生态系研究 总被引：2，自引：0，他引：2
利用围隔式生态实验装置研究了加拿大False河口污染沉积物中重金属Pb、Zn、Cd、Cu在海水环境中的行为。实验模拟了 4种环境条件 :( 1)高生产力 ;( 2 )低生产力 ;( 3 )高悬浮物含量 ;( 4 )还原环境。结果表明 ,污染沉积物中重金属在海水环境中的行为既取决于元素自身性质 ,亦受外界环境条件制约。还原环境能抑制重金属的释放 ,有助于体系中原有的重金属清除出水柱。低生产力条件下 ,Pb、Zn表现出释放行为 ,而高生产力和高悬浮物含量条件下 ,Pb、Zn表现出先释放后迁移 ,而Cd、Cu则呈现出相反的图象。研究了实验期间 4种重金属释放与迁移的净通量 ,表明氧化条件下Cu、Zn净释放通量比Cd、Pb高 1～ 2个量级。研究表明 ,添加粘土及向还原环境倾倒均有助于减轻污染沉积物倾倒后重金属的二次污染 相似文献
2.
莱州湾滨海湿地沉积物重金属的空间分布 总被引：8，自引：0，他引：8
通过研究莱州湾河口区滨海湿地沉积物重金属Pb,Zn,Cd,Cu的含量变化,分析表层沉积物及柱状沉积物,以期了解莱州湾河口区滨海湿地重金属含量的区域性变化,并从柱状沉积物剖面了解沉积物重金属累积的历史变化。研究结果表明,莱州湾河口区与邻近海域沉积物重金属含量在空间分布上与垂直分布上均呈现一定幅度的变化,且高浓度重金属显示区域内重金属呈现污染状况;在沉积物柱状剖面中,发现重金属含量在上层有大幅度增加之现象。另外,利用围隔式生态实验装置研究了该滨海湿地区域污染沉积物中重金属Pb,Zn,Cd,Cu在海水环境中的行为。结果表明,海水中的还原环境能抑制污染沉积物中重金属的释放,有助于体系中原有的重金属清除出水,而低生产力条件下,Pb,Zn表现出释放行为;高生产力和高悬浮物含量条件下,Pb和Zn表现出先释放后迁移,而Cd和Cu则呈现出相反的现象。 相似文献
3.
黄河水下三角洲位于半封闭的渤海内部,海底沉积物中重金属Cu污染严重,且该区域多发风暴潮,引起沉积物再悬浮甚至液化,导致沉积物中重金属Cu重新释放进入海水中。本研究以黄河口粉质土作为底床,采用室内波浪水槽试验模拟重金属Cu在不同水动力条件下,通过静态扩散、底床未液化状态下再悬浮以及底床液化状态下再悬浮3种方式进入上覆水体的释放过程。结果表明:上覆水体中重金属Cu的浓度分布与悬浮泥沙浓度分布密切相关,呈现出一致的变化规律;沉积物液化会明显促进重金属Cu向上覆水体中释放,底床液化再悬浮阶段上覆水体中溶解态Cu的浓度为静态扩散阶段的18倍,为底床非液化再悬浮阶段的11倍;此外,底床液化会导致沉积物中重金属Cu向深处扩散,扩散深度约为沉积物液化深度的一半。 相似文献
4.
以黄河口海域表层沉积物为研究对象,研究沉积物对重金属Cu、Pb的吸附特性,将沉积物筛分为4种粒级,探讨粒度、pH值、吸附时间和吸附剂初始浓度对重金属吸附的影响。结果表明:沉积物粒径越小,对重金属的吸附量越大;吸附平衡时间有所差异,但在1.5h均能达到吸附平衡;吸附量均随pH值升高而逐渐增加,但铜的吸附较铅的吸附速度快;铜的吸附量与吸附剂初始浓度呈线性关系,而铅的吸附量在初始浓度较低时变化明显,随初始浓度增加吸附量增加减小;沉积物对铜吸附等温线符合Langmuir型,铅吸附等温线符合Freundlich型,吸附类型存在差异。重金属在沉积物中的吸附规律研究为黄河口海域污染调查及治理提供了科学依据。 相似文献
5.
长江水下三角洲沉积物柱状样重金属垂向分布特征 总被引：6，自引：1，他引：5
对长江水下三角洲3个沉积物柱状样进行粒度分析、210Pb测年,并测定其中Cr、Cu、Pb、Zn等重金属元素和Al等常量元素的含量,得到了沉积物粒度、粘土含量、重金属含量的垂向分布曲线和沉积物测年数据。通过相关分析来研究沉积物中的Cr、Cu、Pb、Zn等重金属、粒度、Al相互之间的关系;以Al为参照元素对这4种重金属进行归一化处理,分析其归一化前后的垂向分布特征。结果表明,Cr、Cu、Pb、Zn 4种重金属元素在此区域的地球化学行为相似,其分布受细颗粒沉积物的吸附和胶体的絮凝作用共同控制;近一二十年来,该区域的Cr、Cu、Pb含量并没有显著增加,Zn有轻微污染。此外,CJ19柱中Cu存在异常峰值,可能是特大风暴潮事件对研究区浅水区底质沉积物中重金属的分布造成的影响。 相似文献
6.
文章对比分析了珠江口和北部湾海域附近沉积物重金属元素Zn、Pb、Cu、Cr和沉积物粒度之间的相关性,用沉积物富集系数法和潜在生态危害指数法对两个海域海底沉积物的4种重金属元素污染程度和生态风险进行了评价。结果表明,在黏土和粉砂沉积物中重金属富集程度大。Cu在两个区域均达严重污染程度,Zn、Pb、Cr在珠江口沿岸均达到中等污染程度,在北部湾部分区域达到中等污染程度。珠江口的潜在生态风险等级由低级到高级不等,北部湾生态风险等级均为低级。 相似文献
7.
根据日照近海13个站位表层沉积物粒度和重金属含量测试结果，分析了研究区表层沉积物粒度和重金属含量分布特征，采用地累积指数法和潜在生态风险指数法评估了研究区重金属污染状况和潜在生态风险，探讨了重金属的来源和控制因素。结果表明，研究区表层沉积物可分为粉砂、粉砂质砂、砂质粉砂等3种类型，沉积物类型主要呈大致平行岸线的条带状分布，由岸向海依次为粉砂 砂质粉砂 粉砂质砂。研究区表层沉积物中Cr、Zn、Pb、As、Cu、Cd、Hg等重金属的平均含量由高到低依次为45.5、21.8、16.4、8.5、4.8、0.113、0.11 μg/g。从空间分布特征来看，Cr、Cu、Zn和Pb高值区主要出现在付疃河口近岸和研究区中西部海域，Cd和As高值区位于研究区中东部海域。污染状况评估显示，Cr、Cu、Zn、As未出现污染；Cd轻度污染，个别站位达到中度污染，Hg、Pb部分站位呈轻度污染。潜在生态风险等级依次为：Cd＞Hg＞Cu＞As＞Pb＞Cr＞Zn，其中Cd和Hg表现为中生态风险，个别站位Cd为高风险危害。表层沉积物中Cu、Cr、Zn、Hg和Pb元素主要来源于陆源细粒物质的输入，Cd和As元素可能来源于钢铁冶炼、煤炭燃烧、农药、化肥以及海水养殖等。研究区表层沉积物中重金属空间分布主要受物源控制。 相似文献
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在模拟双壳类肠胃消化液的弱酸性(pH=4)条件下对胶州湾8个站位沉积物中的重金属进行浸提,探究重金属的生物可利用性,并以改进的平均沉积物质量基准法(SQG-Q)评估重金属的生态风险。浸提结果表明,胶州湾沉积物中各重金属释放量(mg·kg~(-1))由高到低依次为:Zn(39.21)Cu(20.88)Cr(18.32)Pb(10.69)As(1.00)Cd(0.125)Hg(0.021),释放量较高值多出现在湾西南角的S7站位。沉积物中重金属各形态的释放率由高及低依次为:弱酸溶解态(88.21%)可氧化态(16.39%)可还原态(15.95%)残渣态(1.36%),即重金属的释放主要与弱酸溶解态含量有关。各重金属总释放率表明,Cd在所有重金属中的稳定度最差,而Hg和As则较高。生态风险评价表明,研究区域内除S7、S3站位具有中等程度的潜在不利生物毒性外,其它站位重金属的生物毒性效应均较弱。 相似文献
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Samples of anoxic intertidal sediments from the Mersey Estuary, north-west England, have been used in laboratory experiments to determine the rates and extents of metal (Cu, Zn, Fe, Mn) releases to solution under conditions of controlled resuspension and reoxidation. An experimental system for the study of sediment-water interactions at various temperatures, salinities, pHs and oxygen concentrations is described. The results indicate rapid initial losses of Fe and Mn from sediment but not Cu and Zn with longer term readsorption of Fe and Mn to give partitioning between the aqueous/ sediment phases for all four metals which is similar to that under the initial anoxic conditions. Cu and Zn show small, but measurable, net losses from the aqueous phase to the reoxidized sediment. Salinity variations exert little influence on the processes observed, but increasing temperature produces increased Cu, Zn and Mn in the dissolved fraction at equilibrium conditions. Exchanges of Cu and Zn between the sediment/water phases are rather insensitive to pH or oxygen concentration, but Fe and Mn do respond to increasing pH which suppresses their initial release on oxidation. Low oxygen concentrations can result in a slow but significant release of Fe. In relation to trace metal pollution in estuaries and biological availability, the results suggest that the resuspension and oxidation of polluted anoxic sediments is not an important process because of scavenging of soluble metals on to the resuspended material. 相似文献
12.
Li Jinxi Du Ronggui Zhang Gongxun C. S. Wong R. W. Macdonal W. K. Johnson 《海洋学报(英文版)》1990,9(3):389-403
The pathway and fate of heavy metals were studied in 10m3 enclosures at Xiamen Bay in 1985. The dissolved metals added are removed rather quickly during the first days, and their half-removal times ( t1/2) (d) are as follows: Pb 5. 4-5. 8, Hg 6. 7-14, Zn 11-22, Cu 16 - 29, and Cd 30-89. Zinc is transferred biologically to particles during phytoplankton bloom. The main Fate of added metals after 27 days is as follows; over 80% Cd and 60% Cu remain in dissolved phase, more than 60% Pb and 50% Hg transfer to settling settlement, while Zn is equally distributed in dissolved phase and settling settlement. The wall uptake is less than 2% of the total metals added. Organic materials play an essential role in the partition and the transfer of heavy metals in water column. Terrigenous and autochthonous particles show different affinities to different metals. Most heavy metals associate weakly with zooplankton. The Binding of Cd, Pb, Zn and Cu to the particles shows distinctive features related to the diagenetic 相似文献
13.
Suspended matter from rivers in the Russian Far East was leached by seawater to assess the extent of Zn, Cd, Pb, and Cu release from the land-derived solids to estuarine and coastal waters. The concentration of solids in the leaching experiments was 0.25 g/l. The suspended matter used varied in metal content from background levels to heavily contaminated.The concentration of Zn, Cd, Pb, and Cu in the leaching solution after 1, 4, 24, 48, and 96 h was determined by anodic stripping voltammetry. Measurable Cd was transferred from river suspended matter to seawater with both background and elevated Cd concentrations, though the amount of Cd released was different. The increase in Zn and Pb in solution was observed only at the enriched concentration of metals in the suspended solids. The Cu transfer into solution was more pronounced from material with elevated Cu concentration, but the amount of degradable organic matter in the solid phase was more important.The losses of metals from the riverine solids varied from 60% to 80% of total concentration for Cd to negligible for Pb, independent of contamination. The Zn loss depended on the initial concentration in the solids and decreased from 11–16% for the heavily contaminated suspended matter to 3–8% for the moderately enriched ones and to negligible for the pristine solids. Cu loss varied from 1% to 30% of total content, with no clear dependence on concentration in the suspended matter.The significance of additional input of dissolved metals to estuarine and coastal waters from remobilization was assessed by comparison with the initial concentration of dissolved metals in river water. Such experiments could be used to assess the water quality impact of atmospheric fallout of contaminated solids and storm drainage from the urbanized areas, in addition to river suspended matter studies. 相似文献
14.
胶州湾近岸沉积物-海水汞的释放研究 总被引：2，自引：0，他引：2
本文通过模拟实验研究了胶州湾海泊河口和李村河口沉积物中的汞在不同环境条件下向海水的释放,并对汞的释放动力学数据进行了拟合。总体上两种沉积物汞的释放浓度分别为1.41~5.99μg/L和1.06~3.62μg/L,最大释放率分别为2.7%和3.4%,对胶州湾潮间带水质产生较大的影响。海水的pH值、温度和沉积物厚度都会影响汞的释放。pH<7时,汞的释放作用随pH值的升高而降低,pH>7时,汞的释放作用随pH值的升高而增大;海水温度越高,汞的释放作用越强;随沉积物厚度的增加,汞的释放量增加,释放率降低,海泊河口和李村河口沉积物的有效厚度分别为3.5cm和2.5cm。汞的释放动力学拟合结果表明多个方程都能较好的描述汞的释放动力学过程,其中以Ho的二级动力学方程拟合结果最好。 相似文献
15.
Chemical and enzymatic reagents have been employed to determine available concentrations of Fe, Mn, Cu and Zn in contaminated estuarine sediment. Gastric and intestinal enzymes (pepsin, pH 2, and trypsin, pH 7·6, respectively) removed significantly more metal than was water-soluble or exchangeable (by seawater or ammonium acetate), while gastro-intestinal fluid of the demersal teleost, Pleuronectes platessa L. (plaice), employed to operationally define a bioavailable fraction of contaminants, generally solubilized more metal than the model enzymes. Manganese was considerably more available than Fe under these conditions and it is suggested that the principal mechanism of contaminant release is via surface complexation and reductive solubilization of Mn oxides, a process which is enhanced under conditions of low pH. Of the chemical reagents tested, acetic acid best represents the fraction of Mn (as well as Cu and Zn) which is available under gastro-intestinal conditions, suggesting that the reducing tendency of acetate is similar to that of the ligands encountered in the natural digestive environment. Although the precise enzymatic and non-enzymatic composition of plaice gastro-intestinal fluid may be different to that encountered in more representative, filter-feeding or burrowing organisms, a general implication of this study is that contaminants associated with Mn oxides are significantly more bioavailable than those associated with Fe oxides, and that contaminant bioavailability may be largely dictated by the oxidic composition of contaminated sediment. 相似文献
16.
厦门港湾潮间带沉积物中汞的赋存形态及其释放动力学 总被引：2，自引：0，他引：2
所研究的沉积物样品采自福建省厦门市的港湾潮问带地区,选择了10μg／dm’的汞标准使用液对采集回来的沉积物样品进行了预污染处理,利用预污染后的沉积物样品,在实验室中进行了一系列的汞释放动力学实验．实验结果表明,汞的释放量较低,达到释放平衡时的释放量小于5μg／kg,释放过程可分为2个阶段：前8h为快速释放阶段,之后为慢速释放阶段,大约在24h达释放平衡．采用了Tessier五步提取法对未污染过的沉积物原样及进行过预污染处理的沉积物样品进行了汞的形态分析,结果表明通过污染实验吸附到沉积物上的汞的各形态含量大小顺序为：HgS为主的惰性汞〉单质汞〉盐酸溶无机汞及甲基汞〉有机结合、螯合态汞〉水溶态、交换态等活性汞． 相似文献
17.
Rob F. Nolting Wim Helder Hein J. W. de Baar Loes J. A. Gerringa 《Journal of Sea Research》1999,42(4):2393
Dissolved and particulate trace metals (Cu, Cd, Pb, Zn, Ni, Fe and Mn) measured at six stations along the Scheldt estuary in October/November 1978 are compared with more recent data. Based on Ca content in the suspended matter, three distinct geochemical regions could be distinguished: the upper estuary (salinity 1–7) dominated by fluvial mud, mid-estuary (salinity 7–17) where the composition of the suspended matter remained relatively constant, and the lower estuary where marine mud prevailed. Re-suspension of sediments is the major factor controlling the composition of the particles in the upstream region. Anoxic conditions prevailed in the upper part of the estuary extending to a salinity of 15 in 1978, while at present the seaward boundary of the anoxic water body is located at less saline waters. Furthermore, the present-day metal load is much lower than in 1978. As a consequence of the changed situation, maxima in dissolved concentrations of redox-sensitive metals in the mid/lower estuary have moved as well, which affects the trace metal re-distribution pattern. In the anoxic zone, exchange processes between dissolved and particulate metal fractions were strongly redox regulated, with Fe and Mn as excellent examples. Iron was removed from the dissolved phase in the early stages of mixing resulting in an increase in the suspended particulate matter of the leachable ‘non-residual' Fe fraction from 2 to 3.5%. Due to its slower kinetics, removal of Mn from solution occurred in mid-estuary where oxygen concentrations increased. Cu, Cd and Zn on the contrary were mobilised from the suspended particles during estuarine mixing. External inputs of Pb, and to a lesser extent of Cu, in the lower estuary resulted in the increase of their particulate and the dissolved concentrations. Calculated Kd (distribution coefficient) values were used to assess the redistribution between the dissolved and particulate phase of the investigated metals. Due to the existence of the anoxic water body in the upper estuary, the importance of redox processes in determining the Kd values could be demonstrated. The sequence of Kd values in the upper estuary (Fe, Cd, Zn, Pb > Cu > Ni, Mn) is significantly different from that in the lower estuary (Fe > Mn > Pb, Ni, Zn, Cu, Cd). Thus, in such a dynamic estuary single metal-specific Kd values cannot be used to describe redistribution processes. 相似文献
18.
The release and removal behaviour of Cd, Cu, Co, Ni, Pb and Zn from the sediment of Xiamen Harbour to sea water have been studied under ultra-clean laboratory condition within 168 b. Initial rapid increases in dissolved Cu, Pb, Zn and Co were observed in the first six hours and twelve hours respectively after addition of various amounts of sediment. Then Pb and Co decreased to background values, while Zn decreased to less than the background value and Cu remained unchanged. Cd and Ni did not increase during the experiment. The results indicated that the weakly bound heavy metals were released from the sediment through desorption or exchange. Simultaneously, they might form complexes or be adsorbed in colloids or particles. The two processes existed simultaneously, changing with time and conditions. 相似文献
19.
Partitioning of metals (Fe,Pb, Cu,Zn) in urban run‐off from the Kaikorai Valley,Dunedin, New Zealand
Urban run‐off from a catchment in Dunedin, New Zealand was sampled and chemically characterised (iron (Fe), lead (Pb), copper (Cu), zinc (Zn) in total and <0.4 (im fractions, suspended solids, nitrogen (N), phosphorus (P), dissolved organic carbon, major ions, pH) during base flows, and storm flows from five rainfall events. Fe and Pb were found to be predominantly particle‐associated (>0.4 μm) and their concentrations increased significantly at the beginning of storm run‐off. In contrast, the majority of Cu and Zn was found in the <0.4μm fraction before rainfall events but during the initial period of storm flows a significant proportion of Cu and Zn was also present in the >0.4 μm fraction. The results indicate that Cu and Zn may be more bio‐available, and more difficult to remove by storm‐water treatment, than Pb. The pH level and the concentration of major ions (Ca+2, Na+, Mg+2, K+), dissolved reactive phosphorus, and nitrate generally decreased during storm flows as a result of dilution by rainwater. Concentrations of total N and P often increased during the initial period of storm run‐off, which was likely because of wash‐off of particulate plant material. 相似文献