Geochemistry and acidity of sulphide-bearing postglacial sediments of western Finland

The geochemistry, mineralogy, acidity and electric conductivity of sulphide-bearing postglacial sediments located on the coastal plains of western Finland were studied. Grain size and mineralogical analysis (eight samples studied) indicated that the sediments are silts dominated by primary minerals (quartz, feldspars), and that the clay fraction (<2µm), which made up less than one-third of the bulk samples, is enriched in phyllosilicates but depleted in quartz and feldspars, relative to bulk samples. As compared to the metal contents of the fine-fraction of glacial till (data of the Geological Survey of Finland), the fine sediments appear to be enriched in sulphur (median = 0.54%) and trace metals such as Ni (31 µg g^–1), Zn (90 µg g^–1), Co (13 µg g^–1), Cr (48 µg g^–1) and V (50 µg g^–1). Statistical analysis indicated that aluminosilicates are the principal carrier phases of trace metals, and that sulphides and organic matter only partially control the distribution of elements other than S and C. A 3-g portion of 232 samples was oxidised in the laboratory by atmospheric oxygen for a period of 1 year. After this period of oxidation, 15 ml of water was added, after which pH and electric conductivity of the suspensions (sediment:water, 1:5) were measured. The quantities of elements mobilised by the oxidation was calculated from the dissolved concentrations found in 3 g of oxidised sediment suspended in 30 ml of deionised water (eight samples studied). The results of the experiment showed that the impact of sulphide oxidation on the pH and conductivity of the sediments is large, and that a high proportion (>13%) of the aqua-regia extractable contents of several elements (Co, Mn, Ca, Ni, Zn, Sr, Na and B) are mobilised at oxidation. Because of the high quantities of acidity and metals liberated at oxidation, it is argued that stream-water quality, which is poor in the study area, will not improve unless artificial draining is restricted in areas of sulphide sediments.     

The effects of different carbon sources on microbial mediation of arsenic in arsenic-contaminated sediment

Changes in speciation and mobility of As by indigenous bacteria in As-contaminated sediments (339 mg/kg) from an abandoned Au–Ag mine area in Korea were investigated after biostimulation with a variety of carbon sources, including acetate, lactate and glucose in batch experiments. Sequential extraction analysis designed to determine the form of As occurrence revealed that 40 and 47% of As were present in the sediment as Fe-associated and residual fractions, respectively. After 22-day incubation with acetate and lactate, the presence of indigenous bacteria increased the amount of total dissolved As from both Fe-associated and residual fractions in the sediment. More than 99% of dissolved As existed as As(V) in biotic slurries in contrast to sterile controls (less than 50% of total dissolved As), which indicated that indigenous bacteria transformed some dissolved As(III) to As(V). In real environments, depending on the pH, microbially-produced aqueous As(V) may be either immobilized through adsorption or reduced to As(III) after migration to the anoxic subsurface.     

Temporal variation and distribution of trace metals in freshwater and fish from Calabar River, S.E. Nigeria

An investigation on the abundance and distribution of trace metals (Fe, Cu, Zn, Mn, Cr, Cd and Pb) in water, and nine species of fish samples from Calabar river was carried out in 1992. The concentrations of iron (6000–7240gl^–1), zinc (4910–7230gl^–1), and cadmium (3–7gl^–1) showed moderate pollution while those of copper (420–630gl^–1), manganese (23–48gl^–1), chromium (<10–20gl^–1) and lead (<1–10gl^–1) in water were well below WHO permissible levels. Significant seasonal changes (0.001p0.25) were obtained for iron, copper, zinc, manganese and cadmium in water. Furthermore, iron, zinc and cadmium showed statistically significant spatial changes (0.005p0.10). Of the nine fish species studied, no statistically significant relationship between body weight and the concentrations of the metals was observed. The concentrations of the metals per mean total body weight apparently decreases in the order Fe>Zn>Cu>Mn>Pb>Cd=Cr and were within the limits that were safe for consumption.     

水环境中痕量重金属生物活性形态的分析

水环境中痕量重金属的生物活性形态,包括生物可吸收态和生物毒性形态,这种形态的分析是重金属形态分析研究的一个重要发展方向。对于水环境中重金属对生物的毒害现状评价、潜在危害预测以及水环境容量的确定、排放标准和污染治理方案的制定,具有重要意义。本文总结了各种物理化学法重金属形态分析的结果与生物测试重金属形态测定结果之间的相关性,进而探讨了应用物理化学方法进行金属生物活性形态分析的可行性和特点。     

大坞河流域重金属污染与五节芒光谱效应关系研究

以大坞河流域五节芒（Miscanthus floridulus）可见一近红外光谱以及叶片样本Cu、Zn、Fe元素质量分数监测数据为基础，对研究区内五节芒中重金属质量分数特征、光谱特征及两者的相关性进行了探讨。结果表明：五节芒叶片中3种金属元素的质量分数都较高；从上游到下游，五节芒叶片中Cu质量分数整体呈逐渐降低的趋势，五节芒光谱反射率在可见光区和近红外区均增加，红边“红移”（向长波方向飘移）强度逐渐减小；同时，五节芒叶片中Cu质量分数与五节芒可见光区、近红外区光谱反射率积分值呈负相关性，与红边“红移”强度、土壤中Cu质量分数呈正相关。并由此得出五节芒光谱特征中A1、A2、S等3项指标能够较好反映土壤的Cu污染程度，经进一步深入研究，可以将五节芒作为监测矿区土壤Cu污染的指示植物。     

Cd和Cu在草甸棕壤-植物系统中行为特性的研究

在沈阳生态站开展了重金属迁移积累行为特性的试验研究，探讨了不同重金属元素在土壤及作物体内迁移积累变化规律。外源重金属元素Cd、Cu施入土壤后，无论是低剂量还足高剂量处理，水田土壤Cd元素已迁移到45cm的深度，而Cu元素迁移到30cm的深度。早田土壤低剂量和高剂量处理Cd迁移到30cm，而Cu元素只有高剂量处理迁移到30cm的深度。土壤Cd、Cu元素向下层迁移的量微乎其微，重金属元素大多滞留在土壤表层。水稻、玉米吸收的Cd大部分积累在作物体的根和茎叶中，而Cu大部分积累在作物体的根系中，Cd、Cu籽实吸收量占植物体总吸收量的1．16％～3％。水稻、玉米地上部吸收Cd的量〉地卜部吸收Cu的量，在作物体中Cd的迁移能力强于Cu的迁移能力。     

Compound pollution of Cd,Pb,Cu,Zn,As in plant-soil system and its prevention

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Soil heavy metal pollution from Pb/Zn smelting regions in China and the remediation potential of biomineralization

Smelting activities pose serious environmental problems due to the local and regional heavy metal pollution in soils they cause. It is therefore important to understand the pollution situation and its source in the contaminated soils. In this paper, data on heavy metal pollution in soils resulting from Pb/Zn smelting (published in the last 10 years) in China was summarized. The heavy metal pollution was analyzed from a macroscopic point of view. The results indicated that Pb, Zn, As and Cd were common contaminants that were present in soils with extremely high concentrations. Because of the extreme carcinogenicity, genotoxicity and neurotoxicity that heavy metals pose, remediation of the soils contaminated by smelting is urgently required. The primary anthropogenic activities contributing to soil pollution in smelting areas and the progressive development of accurate source identification were performed. Due to the advantages of biominerals, the potential of biomineralization for heavy metal contaminated soils was introduced. Furthermore, the prospects of geochemical fraction analysis, combined source identification methods as well as several optimization methods for biomineralization are presented, to provide a reference for pollution investigation and remediation in smelting contaminated soils in the future.     

福建中、东部沿海主要养殖贝类体重金属的含量与评价

根据2000年11月福建中、东部沿海养殖贝类体重金属的检测资料，分析了牡蛎、菲律宾蛤仔、缢蛏体内重金属的含量水平。结果表明；闽江口附近海域和兴化湾湾顶北部海域养殖的褶牡蛎，体内Zn和Cd的含量明显高于其他养殖区。文中对3种养殖贝类的重金属污染程度进行评价的结果表明：闽中、东沿海的养殖贝类基本未受重金属污染或属微污染水平。     

中国南方某铀尾矿库周缘土壤重金属污染研究

选择中国南方某铀尾矿库周边2条背景剖面（B1、B2）和3条潜在污染剖面土壤剖面（S1、S2、S3）,通过比较各剖面中重金属元素分布,讨论铀尾矿库土壤中外源重金属元素的污染特征、迁移行为.研究表明：（1）相较于背景剖面,邻近铀尾矿库周缘土壤主、微量组分呈显著外源输入特征.（2）应用主成分法分析铀尾矿库周缘土壤外源重金属元素来源,发现尾矿库是该地区土壤重金属污染的直接来源,并向周缘土壤输送As、Pb、Sb、Cd、U等重金属污染元素.（3）分析铀尾矿库周缘土壤中尾矿库源重金属元素（As、Pb、Sb、Cd、U）同主、微量组分与理化参数的关系,发现潜在污染土壤中各金属元素与LOI（烧失量）、K、P呈较密切相关,与Na、Ca、Mn、pH、Fe存在次等相关性;由重金属淋溶迁移程度可知,重金属在潜在污染剖面（S1、S2）呈显著富集特征;各重金属横向迁出特征表明,其迁移至铀尾矿库周缘土壤具有不同的迁移方式.（4）铀尾矿库周缘近源土壤（距尾矿库30m左右）As、Pb、Sb、Cd、U呈显著污染,含量远大于国家农用地土壤环境质量评价标准和所在省份土壤元素背景值,应对该尾矿库潜在风险进行及时管控.