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971.
Xinbin Feng Hongmei Jiang Guangle Qiu Guanghui Li 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2594-2603
From October 2003 to September 2004, we conducted a detailed study on the mass balance of total mercury (THg) and methylmercury (MeHg) of Dongfeng (DF) and Wujiangdu (WJD) reservoirs, which were constructed in 1992 and 1979, respectively. Both reservoirs were net sinks for THg on an annual scale, absorbing 3319.5 g km−2 for DF Reservoir, and 489.2 g km−2 for WJD Reservoirs, respectively. However, both reservoirs were net sources of MeHg to the downstream ecosystems. DF Reservoir provided a source of 32.9 g MeHg km−2 yr−1, yielding 10.3% of the amount of MeHg that entered the reservoir, and WJD Reservoir provided 140.9 g MeHg km−2 yr−1, yielding 82.5% of MeHg inputs. Our results implied that water residence time is an important variable affecting Hg methylation rate in the reservoirs. Our study shows that building a series of reservoirs in line along a river changes the riverine system into a natural Hg methylation factory which markedly increases the %MeHg in the downstream reservoirs; in effect magnifying the MeHg buildup problem in reservoirs. 相似文献
972.
Polychlorinated biphenyl congeners and organochlorine insecticides in the water column and sediments of Daya Bay, China. 总被引:29,自引:0,他引:29
J L Zhou K Maskaoui Y W Qiu H S Hong Z D Wang 《Environmental pollution (Barking, Essex : 1987)》2001,113(3):373-384
Samples of sub-surface water, suspended particulate matter (SPM) and surface sediments collected from Daya Bay, China have been analysed for 12 polychlorinated biphenyl (PCB) congeners and 18 organochlorine insecticides, using gas chromatography electron capture detection. Total PCB levels varied from 91.1 to 1355.3 ng l-1 in water and from 0.85 to 27.37 ng g-1 dry weight in sediments. The levels of total organochlorine insecticides were in the range 143.3-5104.8 ng l-1 in water and 2.43-86.25 ng g-1 dry weight in sediment. None of the target compounds were detected in SPM. The levels of total hexachlorocyclohexanes in water varied from 35.5 to 1228.6 ng l-1, whilst in sediments they ranged from 0.32 to 4.16 ng g-1 dry weight. For the sum of dichlorodiphenyltrichloroethanes (DDTs), their levels were in the range 26.8-975.9 ng l-1 in water, and 0.14-20.27 ng g-1 dry weight in sediments. The distribution profiles of these contaminants in water and sediments suggest that there are a number of sources contributing to total contaminant burden in the bay, including soil runoffs, wastewater discharges, sewage outfalls and shipping activites. Ratios of DDT/(DDE + DDD) in the water and sediments indicate recent inputs of such chemicals into the day. The results, therefore, provide important information on the current contamination status of a key aquacultural area in China, and point to the need for urgent actions to stop the use of persistent agrochemicals such as DDT and lindane. 相似文献
973.
复杂景观中营养型非点源污染物时空变异特征分析 总被引:10,自引:4,他引:10
非点源污染的形成不仅受到地表物质来源、景观格局的影响,同时还受到土壤侵蚀过程、降雨过程、灌溉过程、地表和地下水文过程的影响.由于影响非点源污染的因子复杂多样,从而导致它的时空变化较大.正确认识非点源污染的时空变异特征对于科学布设监测点和研究它的变化规律具有重要意义.本文通过野外定点监测,研究了非点源污染的时空变异.结果发现:①干旱年份各种污染物空间变异小于降雨正常年份.②对于不同污染物,无论在干旱年份还是正常年份,地表水中固体悬浮颗粒物的空间变异均较大,其他污染物的空间变异相对较小.③对于固体悬浮颗粒物,干旱年份不同水文期之间的空间变异比较接近,而正常年份的空间变异不同水文期之间差异较大.④非点源污染季节变异较小的监测点主要出现在具有稳定水源和地表径流季节变化较小的地区;而非点源污染空间变异较大的监测点主要出现在山区河流上游地表径流季节变化明显、农业用地面积较大且地表径流季节变化较大和明显受到点源污染影响的地区. 相似文献
974.
环境内分泌干扰物浅析 总被引:5,自引:0,他引:5
国内外对环境内分泌干扰物的研究证实,人类的生殖障碍、发育异常、某些癌症及某些免疫系统、神经系统疾病与环境内分泌干扰物的效应有关,本文对环境内分泌干扰物概念及问题产生背景、种类、对人类健康的危害及作用机制作了浅要的综合分析,并提出了对污染现状的认识与防治对策。 相似文献
975.
太湖地区水稻土表层土壤10年尺度重金属元素积累速率的估计 总被引:34,自引:6,他引:34
以江苏省几个水稻土历年监测的重金属元素变化资料为基础,估计太湖地区水稻土表层土壤的重金属元素积累速率并推算本地区相应的几种环境影响的污染通量.结果表明,Cu/Zn、Pb和Cd的积累速率分别达到0.3~lmg·(kg·a)-1、0.2~1mg·(kg·a)-1和0.3~3μg·(kg·a)-1,它们的年污染通量分别为0.5~1kg·(hm2·a)-1,0.5~1.0kg·(hm2·a)-1,0.5~3.0kg·(hm2·a)-1和0.8~10×10-3kg·(hm2·a)-1.观察到有效态含量的积累速率高于全量.就整个区域来说,Pb、Cd的面源复合污染强度明显较其他环境影响因子大,尤其是Cd的污染通量较国际上的报道偏高,说明本地区环境污染较为严重,仍然是区域环境质量的制约因素本地区土壤重金属元素的变化及其对食物链的影响以及人类健康的影响必须引起广泛的重视. 相似文献
976.
977.
978.
城市污泥植物处理对地表径流和下层土壤的影响 总被引:4,自引:0,他引:4
城市污泥的农业利用逐渐成为世界城市污泥处理处置的最具前景的方式之一。通过设置无污泥+不种植物、污泥+不种植物、污泥+东南景天单种、污泥+东南景天与香芋套种4个处理,对污泥植物处理系统的地表径流以及各处理1年后的下层土壤(20~40 cm)进行了监测。研究结果表明:地表径流中的TN、TP和COD的含量随着时间的推移均有不断下降的趋势,其中,地表径流中的TP含量超出国家污水综合排放中的二级标准。地表径流中Zn、Cd、Cu和Pb的含量随着时间的推移略有上升的趋势,但它们的含量远低于国家污水综合排放标准中的二级标准。处理1年后下层土壤中的氮磷钾和有机质含量明显提高,下层土壤中的Zn、Cd、Cu和Pb含量也有一定程度的增加。 相似文献
979.
Subcellular distribution and chemical form of Cd and Cd-Zn interaction in different barley genotypes 总被引:33,自引:0,他引:33
A hydroponic experiment was carried out to study the genotypic difference in subcellular distribution and chemical form of Cd and Zn uptake and their interaction in four barley genotypes. Increased Cd level in the medium caused a significant increase of Cd concentration in all fractions of roots/shoots, with most accumulation in FI (cell wall) and FIV (soluble). In root, the greatest amount of Cd was found in extraction solution of 2% HAC or 0.6M HCl, followed by 1M NaCl (20%), and lowest in extraction of 80% ethanol or d-H2O. While in shoot, the highest value of Cd accumulation was recorded in the fractions extracted by 1M NaCl and 2% HAC, followed by 0.6M HCl or d-H2O, and least in 80% ethanol extraction solution. There was a distinct difference among genotypes in Cd concentration in subcellular and chemical forms and it was found that the Cd-sensitive genotype Wumaoliuling, in comparison with the other three Cd-resistant genotypes, had higher Cd concentration in chloroplast-shoot/trophoplast-root (FII), membrane and organelle (FIII) and in inorganic and water-soluble Cd of roots, while lower in FI, FIV and pectates/protein integrated Cd. After 48 h of Cd treatment, the plants were replaced into Cd-free nutrient solution and grown for 72 h, a significant decrease in Cd concentration of root FI was observed, with less Cd reduction in Wumaoliuling. In comparison with control (no Cd), addition of Cd significantly increased Zn accumulation in chloroplast (FII), with least increase in Wumaoliuling. The Zn content in the other 3 fractions decreased significantly with addition of Cd, especially in roots, while Wumaoliuling was the most severely affected genotype. Moreover, it could be suggested Zn supplement could significantly reduce Cd concentration in root trophoplast and in shoot soluble fraction of Cd-treated plants. 相似文献
980.