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521.
522.
缺氧沉积物中硫化物对镉的生物可利用性的影响 总被引:2,自引:0,他引:2
镉是水环境中主要的金属污染物质,趋向于在沉积物中富集,对底栖生物造成潜在的威胁,并且通过食物链最终影响人体的健康.已经证明,作为沉积物中两大主要污染物的有机物和金属,有机碳是控制沉积物中非离子态有机化合物生物可利用性的主要因子[1],因此利用有机碳归一化方法判断沉积物是否受到有机物污染成为可能,而沉积物中金属的毒性或它的生物可利用性会受到诸如生物、物理和化学因子的影响,其中沉积物的部分化学组成会影响金属在固相与间隙水之间的分配,从而成为控制金属生物可利用性的关键因子[2,3]. 相似文献
523.
采用体内、体外染毒实验,研究了海洋中常见污染物0#柴油、二甲苯以及重金属镉离子(Cd2+)对毛蚶(Scapharca subcrenata)肌肉超氧化物歧化酶(SOD)活性的影响.结果表明,在实验剂量范围内,3种污染物对毛蚶肌肉中SOD均表现出不同程度诱导作用;0#柴油和二甲苯体内、体外染毒对毛蚶SOD活性影响规律基本一致,这两种污染物对毛蚶SOD活性变化的剂量-效应曲线均为抛物线型;Cd2+在体内、体外染毒对毛蚶肌肉SOD活性诱导曲线均不呈抛物线型,低浓度Cd2+对毛蚶SOD活性表现为显著诱导,随后曲线迅速下降,表明毛蚶对Cd2+污染反应十分敏感,也表明Cd2+对毛蚶毒性作用较强,3种毒物对毛蚶的毒性强弱次序为,Cd2+,0#柴油、二甲苯. 相似文献
524.
Abstract. Tethya microstella, T. orphei, T. robusta, and T. seychellensis live in sympatry in a Maldivian coral reef lagoon (Gangehi Island, Ari Atoll). A morphological, morphometric, and electrophoretical study of these species show that their Maldivian populations are well separated morphologically and genetically. The genetic distances and the other data are more consistent with an immigration than with a local speciation hypothesis. Their coexistence may be explained by a differentiation in ecological requirements. The four species inhabit the shallow water biotope of the lagoon among the rubble of dead corals. Our data show that T. orphei and T. seychellensis occupy the upper rubble layer, T. microstella and T. robusta the lower one. This distinction agrees with the different morpho-functional features of the two pairs of species. 相似文献
525.
海南五指山树仔菜重金属镉的生态地球化学研究 总被引:3,自引:0,他引:3
对海南省五指山市南圣镇什贺村(属全海南岛表层土壤背景下的镉非异常区)的树仔菜和红山镇什蛇田村(镉异常区)的包心菜、生菜、芥菜、茼蒿菜的根系土、植物样进行了配套采集分析。结果表明,所采集的树仔菜样品镉含量个别超标,镉的土壤环境质量大都符合国家规定的标准;但是研究区土壤中镉的有效量占比远高于其他元素,镉较其他元素更倾向于在树仔菜中富集,而且树仔菜较其他品种蔬菜更强烈地选择性吸收富集镉,更兼镉在树仔菜中的富集部位恰恰就是可食部分茎和叶,因此,树仔菜的食用安全性不容忽视。另外,土壤中的镉测试结果表明,对树仔菜的种植地要进行大比例尺的土壤详查评价工作,以精确圈定安全的种植地域,确保树仔菜的食用安全性。 相似文献
526.
The breach in the dam of a tailing pond in the processing plant of a gold mine in Baia Mare (NW Romania) in January 2000 lead to an ecological disaster in the rivers Szamos and Tisza. It was mainly caused by the released slurries containing cyanides and heavy metals. The investigation of surface sediment samples and depth profiles of the years 2000 and 2001 documented the pollution of the rivers Szamos and Tisza on Hungarian territory. In the Szamos and large areas of the Tisza floodplains a significant enrichment with the heavy metals Pb, Cd, Cu, and Zn is existent. The identification of the binding forms with sequential extraction showed that Cd and Zn exist in an easily available form. Therefore the remobilization is possible and an environmental hazard in the downstream areas must be considered. The anthropogenically caused portions of heavy metal concentrations decrease considerably with increasing distance to the mining region. The comparison of the concentrations of heavy metals in both years shows that the pollution is not only caused by the accident in January 2000. The increase of concentrations is based on the permanent input of pollutants into the rivers. The pollution is mainly caused by the erosion of exposed tailing dumps and the poor maintenance of the treatment plants. 相似文献
527.
A mid-twentieth century reduction in tropical upwelling inferred from coralline trace element proxies 总被引:3,自引:0,他引:3
Matthew K. Reuer Edward A. Boyle Julia E. Cole 《Earth and Planetary Science Letters》2003,210(3-4):437-452
The Cariaco Basin is an important archive of past climate variability given its response to inter- and extratropical climate forcing and the accumulation of annually laminated sediments within an anoxic water column. This study presents high-resolution surface coral trace element records (Montastrea annularis and Siderastrea siderea) from Isla Tortuga, Venezuela, located within the upwelling center of this region. A two-fold reduction in Cd/Ca ratios (3.5–1.7 nmol/mol) is observed from 1946 to 1952 with no concurrent shift in Ba/Ca ratios. This reduction agrees with the hydrographic distribution of dissolved cadmium and barium and their expected response to upwelling. Significant anthropogenic variability is also observed from Pb/Ca analysis, observing three lead maxima since 1920. Kinetic control of trace element ratios is inferred from an interspecies comparison of Cd/Ca and Ba/Ca ratios (consistent with the Sr/Ca kinetic artifact), but these artifacts are smaller than the environmental signal and do not explain the Cd/Ca transition. The trace element records agree with historical climate data and differ from sedimentary faunal abundance records, suggesting a linear response to North Atlantic extratropical forcing cannot account for the observed historical variability in this region. 相似文献
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