Mercury and methylmercury biogeochemistry in a thawing permafrost wetland complex,Northwest Territories,Canada          下载免费PDF全文

J. Gordon  W. Quinton  B. A. Branfireun  D. Olefeldt 《水文研究》2016,30(20):3627-3638

In arctic and sub‐arctic environments, mercury (Hg), more specifically toxic methylmercury (MeHg), is of growing concern to local communities because of its accumulation in fish. In these regions, there is particular interest in the potential mobilization of atmospherically deposited Hg sequestered in permafrost that is thawing at unprecedented rates. Permafrost thaw and the resulting ground surface subsidence transforms forested peat plateaus into treeless and permafrost‐free thermokarst wetlands where inorganic Hg released from the thawed permafrost and draining from the surrounding peat plateaus may be transformed to MeHg. This study begins to characterize the spatial distribution of MeHg in a peat plateau–thermokarst wetland complex, a feature that prevails throughout the wetland‐dominated southern margin of thawing discontinuous permafrost in Canada's Northwest Territories. We measured pore water total Hg, MeHg, dissolved organic matter characteristics and general water chemistry parameters to evaluate the role of permafrost thaw on the pattern of water chemistry. A gradient in vegetation composition, water chemistry and dissolved organic matter characteristics followed a toposequence from the ombrotrophic bogs near the crest of the complex to poor fens at its downslope margins. We found that pore waters in poor fens contained elevated levels of MeHg, and the water draining from these features had dissolved MeHg concentrations 4.5 to 14.5 times higher than the water draining from the bogs. It was determined through analysis of historical aerial images that the poor fens in the toposequence had formed relatively recently (early 1970s) as a result of permafrost thaw. Differences between the fens and bogs are likely to be a result of their differences in groundwater function, and this suggests that permafrost thaw in this landscape can result in hotspots for Hg methylation that are hydrologically connected to downstream ecosystems. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Assessment of Metal Pollution in Water and Surface Sediments of the Seyhan River,Turkey, Using Different Indexes     

Orkun I. Davutluoglu  Galip Seckin  Cagatayhan B. Ersu  Turan Yilmaz  Bulent Sari 《洁净——土壤、空气、水》2011,39(2):185-194

The aim of this study was to assess the level of heavy metals (Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contamination and enrichment in the surface sediments of the Seyhan River, which is the receiving water body of both treated and untreated municipal and industrial effluents as well as agricultural drainage waters generated within Adana, Turkey. Sediment and water samples were taken from six previously determined stations covering the downstream of the Seyhan dam during both wet and dry seasons and the samples were then analyzed for the heavy metals of concern. When both dry and wet seasons were considered, metal concentrations varied significantly within a broad range with Al, 7210–33 967 mg kg^?1 dw; Cr, 46–122 mg kg^?1 dw; Cu, 6–57 mg kg^?1 dw; Fe, 10 294–26 556 mg kg^?1 dw; Mn, 144–638 mg kg^?1 dw; Ni, 82–215 mg kg^?1 dw; Pb, 11–75 mg kg^?1 dw; Zn, 34–146 mg kg^?1 dw in the sediments while Cd was at non‐detectable levels for all stations. For both seasons combined, the enrichment factor (EF) and the geo‐accumulation index (I_geo) for the sediments in terms of the specified metals ranged from 0.56 to 10.36 and ?2.92 to 1.56, respectively, throughout the lower Seyhan River. The sediment quality guidelines (SQG) of US‐EPA suggested the sediments of the Seyhan River demonstrated “unpolluted to moderate pollution” of Cu, Pb, and Zn, “moderate to very strong pollution” of Cr and Ni. The water quality data, on the other hand, indicated very low levels of these metals suggesting that the metal content in the surface sediments were most probably originating from fine sediments transported along the river route instead of water/wastewater discharges with high metal content.  相似文献   

Effects of Watershed Land Use and Lake Morphometry on the Trophic State of Chinese Lakes: Implications for Eutrophication Control   总被引：1，自引：0，他引：1  

Wenzhi Liu  Quanfa Zhang  Guihua Liu 《洁净——土壤、空气、水》2011,39(1):35-42

Water quality in lakes is influenced by a large number of watershed and lake characteristics. In this study, we examined the relative effects of watershed land use and lake morphology on the trophic state of 19 lakes in the Yunnan plateau and lower Yangtze floodplain, the two most eutrophic regions in China. Trophic state parameters consisted of total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll‐a, Secchi depth, and trophic state index, while lake morphometric variables included area, maximum depth, mean depth, water residence time (WRT), volume, and length to width ratio. Percentages of forest, grassland, cropland, unused land, built‐up land, and water body in each lake's watershed were extracted from a land use map interpreted from Landsat TM images. A t‐test indicated that lower Yangtze floodplain lakes were shallower and had higher percentages of cropland and built‐up land in watersheds than Yunnan plateau lakes. Pearson's correlation analysis indicated that both watershed land use and lake morphometric variables were significantly related to most of the trophic state parameters. However, stepwise regression analyses demonstrated that the trophic state of the lower Yangtze floodplain lakes was mainly controlled by the percentages of cropland and built‐up land in watersheds, while that of Yunnan plateau lakes was mostly determined by the lake depth and WRT. These results suggest that the relative effects of watershed land use and lake morphology on lake trophic state are dependent on the lake's location. This study can provide some useful information in watershed land use management for controlling eutrophication in Chinese lakes.  相似文献   

Downstream patterns of bed sediment-borne metals,minerals and organic matter in a stream system receiving acidic mine effluent: A preliminary study   总被引：1，自引：0，他引：1  

Yingqun Ma  Wenzhou Lu  Chuxia Lin 《Journal of Geochemical Exploration》2011

Different downstream variation patterns were observed for a range of bed sediment-borne metals (aqua regia-extractable fraction) in a subtropical stream system receiving acid mine drainage. Mine-originated Fe tended to be deposited in the acidic (mean pH < 4.9) upstream reach in forms of goethite and/or hematite. In contrast, other metals tended to be transported farther downstream and settled in a low-gradient reach with high pH (mean pH > 5.6). The peak of sediment-borne Al, Be, Ca, Cd, Co, Cu, La, Mn, Ni and Zn corresponded very well with the peak of the sediment-borne organic matter, suggesting a close association between the water-borne organic colloids and the inorganic metal oxides/hydroxides during their transport. The marked increase in the sediment-borne Al and Pb started more upstream than the other metals, suggesting that the water-borne Al and Pb were more susceptible to pH rise-induced precipitation, as compared to the other metals. It appeared that the organic colloids played no important role in Pb transport and settlement. The iron precipitates had a limited role to play in affecting the transport and fates of other metals since they were predominantly formed and deposited in the acidic reach, which made them incapable of scavenging cationic metals by co-precipitation or adsorption.  相似文献   

鸡西盆地城子河组泥岩有机质保存条件研究     

樊馥  张永生  高福红  蔡进功  崔海娜  于鹏 《沉积学报》2011,29(5):980-985

鸡西盆地作为我国东北地区重要的煤炭基地,已在多口钻井中发现油气显示。早白垩世城子河组为一套夹数个海相泥岩层的含煤岩系,形成于滨浅湖—沼泽的沉积环境,为该盆地主力烃源岩层。本次对该层位泥岩样品的常、微量元素全分析结果表明,水体盐度指标Sr/Ba在0.11～0.38之间,碱度指标（Ca＋Mg）＊20/（Si＋Al）为0.2...  相似文献   

东昆仑山玉珠峰冰川雪坑中痕量元素的组成特征   总被引：3，自引：1，他引：2  

李月芳  王宁练  姚檀栋  蒲健辰  时晓兰 《冰川冻土》2011,33(4):752-759

为了认识玉珠峰冰川区域大气中痕量元素的组成和来源,利用高分辨电感耦合等离子体质谱仪对2009年10月采自玉珠峰冰川海拔5800m的一个75cm雪坑中15种可溶性痕量元素（A1、Fe、Ba、Cd、Co、Cr、Cu、Li、Ni、Zn、Pb、Sb、Sr、U和V）的浓度进行了测试．结果表明：痕量元素的浓度变化很大,从最小值1．...  相似文献   

水污染物总量综合权重系数分配方法研究     

孙娟  吴悦颖  叶维丽  文宇立  杨文杰  李舟 《水文》2011,(4):40-44

区域污染物排放总量分配是水污染总量控制的重要内容,分配合理与否将直接影响总量控制工作成效。以陆域排污-水体水质响应空间单元为基础,构建了综合考虑水环境质量、排污及污染治理水平、区域经济实力等因素的总量分配指标体系,提出一套单元的水污染物总量分配综合权重系数计算方法。并将该方法应用于北京市,结果表明本方法较好地解决了目前分配方法中总量目标与水质改善需求衔接不足、分配指标体系过于单一的问题。  相似文献   

污染调查中的水、土样品采集技术          下载免费PDF全文

靳成军  郑继天 《探矿工程》2011,38(11):38-41

地下水污染日益严重。钻探是地下水污染勘察方法中最直接、最准确的技术方法,是地下水污染调查的重要手段之一。通过取心、取样,可以获得地下污染信息。取心、取样质量的好坏对取得的地下水污染调查资料真实性至关重要。在地下水污染调查中,要根据调查场地的条件和调查目的选择合适的采样方法,并严格按照操作规程进行采样,以取得真实、有代表性的样品。  相似文献   

铁锰氧化物对苯酚氧化降解的实验研究     

文丽敏  张骏 《西安地质学院学报》2011,(2):191-195

为了考察铁锰氧化物对酚类污染物的氧化降解能力,采用天然以及合成的铁锰氧化物对苯酚的氧化降解进行对比实验研究。土壤中铁锰氧化物样品分别为天然针铁矿及氧化锰,合成铁锰氧化物样品分别为合成针铁矿及软锰矿。结果表明：苯酚与铁锰氧化物发生氧化还原作用时,还可能与土壤中杂质发生吸附等作用;铁锰氧化物还原反应强度随着反应介质pH值的升高而迅速下降;可用零级反应动力学方程拟合铁氧化物还原溶解反应,针铁矿溶解反应的强度与介质的pH值呈负相关关系;天然针铁矿对酚类污染物的氧化降解能力明显高于合成针铁矿,pH值对天然针铁矿溶解反应影响较大;可用一级指数衰减方程拟合锰氧化物还原溶解反应,锰氧化物溶解反应的强度与介质的pH值呈指数衰减关系;pH值对软锰矿还原溶解反应的影响大于对土壤中氧化锰的影响,pH值越小,影响越显著;对比pH值对铁和锰还原作用的影响发现,在pH=6.5时,锰氧化物仍有较强的氧化性能。  相似文献   

多模型方法在非点源污染负荷中的应用展望   总被引：2，自引：0，他引：2  

王慧亮  李叙勇  解莹 《水科学进展》2011,22(5):727-732

对非点源污染进行定量化和有效控制的方法是通过非点源污染负荷模型对各类非点源的形成、迁移转化以及负荷量进行模拟。然而,流域非点源污染模型的不确定性是单一模型模拟污染负荷面临的重大挑战。借鉴多模型方法在降低水文模型不确定性方面的优越性,通过分析水文模型与非点源污染模型的相通性,提出多模型方法在非点源污染负荷中应用的基本思路并分析了多模型方法在非点源污染负荷估算中面临的挑战,总结了多模型方法在非点源污染负荷应用中的重点和难点问题。  相似文献