北京官厅水库有机氯农药分布特征及健康风险评价

为了研究北京官厅水库中有机氯农药（OCPs）对人体产生的潜在健康危害风险,从位于官厅水库、洋河和妫水河的9个采样点采集了水样和沉积物样品,采用气相色谱法对其中的有机氯农药残留状况进行了测定。结果表明,水样中,17种有机氯化合物的总浓度范围为10．06～87．37ng·L^-1,其中六六六（HCHs,即：α—HCH、β-HCH、γ-HCH和δ-HCH）和滴滴涕（DDTs,即：o,p＇-DDT、p,p’-DDT、p,p＇-DDE和p,p＇-DDD）的含量范围分别为3．93～38．94ng·L^-1和3．71～16．03ng·L^-1,官厅水库及其支流水体受到有机氯农药轻度污染,其周边地区农田排放水是水库中农药的重要来源。沉积物中有机氯农药总含量范围为8．48～24．40ng·g^-1,其中HCHs和DDTs的含量高于其他OCPs的含量,其含量范围分别为1．11～7．73ng·L^-1和2．97～10．52ng·g^-1,沉积物中六六六异构体和滴滴涕类似物的含量组成表明这些农药来自环境中的早期残留。利用健康风险评价模型对官厅水库表层水体中的OCPs所致健康风险的评价结果表明,目前官厅水库中有机氯农药类污染物对人体健康的风险处于较低水平。     

天津污灌区水稻土壤汞形态特征及其食品安全评估

选择天津污水灌溉区作为研究区域,该文的主要研究目的是分析土壤不同形态汞对水稻不同组织中总（THg）和甲基汞MeHg富集的影响以及评估污灌区稻米食用汞暴露风险,并对污灌区土壤溶解与可交换态汞安全阀值进行了初步分析。结果表明,北塘、大沽和北京污灌区稻田土壤THg和MeHg浓度显著高于对照区海河土壤THg浓度。大沽、北京河污灌区和海河土壤汞的形态为残渣态浓度最高,而北塘污灌区为有机结合态浓度最高。由于水稻地上组织中THg浓度受到大气汞浓度影响,各组织中汞浓度在不同污灌区分布规律不同。水稻籽粒的 MeHg 富集系数为1.63～3.70,通过人体每天摄入MeHg量的安全值计算得出土壤溶解与可交换态汞质量分数应低于9.19 ng/g。污灌区食用稻米MeHg暴露对居民健康存在较大风险,人体MeHg每天摄入量超标率达到20.83%。因此,可以对超标土壤进行治理或改变耕作方式来降低土壤污染对人体MeHg暴露造成的影响。     

京杭大运河（徐州铜山段）沉积物表层样品中有机氯农药残留状况

京杭大运河（徐州铜山段）位于南水北调东线工程路线上,利用GC—ECD检测了该段河流7个断面上的沉积物样品中的有机氯农药含量,主要检测出六六六（HCHs）、滴滴涕（DDTs）、六氯苯等。结果表明,总有机氯农药含量范围是57．80～236．65ng·g^-1,其中HCHs、DDTs的含量较高,分别为12．19-43．08ng·g^-1和3．29-135．08ng·g^-1,从蔺家坝到解台闸沿程沉积物中有机氯农药的含量呈下降的趋势,显示有机氯农药的残留物可能主要来自于农田土壤的残留,并且近期无新的污染源输入。     

广州市典型食用鱼类甲基汞含量及风险评估

通过分析广州市区居民消费量较大的7种淡水鱼和5种海水鱼肌肉中甲基汞（MeHg）含量,评估人体通过食鱼摄入MeHg的暴露风险。结果显示,广州市鱼体肌肉中MeHg含量范围为2.39～349μg·kg-1,平均含量为43.4μg·kg-1。不同食性鱼类MeHg含量水平依次为：肉食性〉杂食性〉草食性,处于食物链不同环节解释了这种含量差异。从生长环境来看,海水鱼肌肉的MeHg含量总体上高于淡水鱼。所有鱼中MeHg含量均低于国内外相关标准限值。与国内其他地区商品鱼相比,广州市商品鱼中MeHg含量相当,但明显低于野生鱼。居民通过食鱼摄入的MeHg范围为0.035～0.087μg·kg-1·d-（1bw）,均值为0.050μg·kg-1·d-（1bw）,远低于美国EPA规定的MeHg暴露参考剂量（RfD）值（1.1μg·kg-·1d-1）,也低于WHO和FAO制定的临时性周可承受摄入量（PTWI）（1.6μg·kg-1）。研究结果表明,广州居民食鱼MeHg暴露风险较小,但儿童等敏感人群食用特定鱼类的量和频次要引起一定注意。     

三种有机物料对稻田土壤汞甲基化及水稻汞积累的影响

施用有机物料是水稻生产过程中提高产量的一条重要途径，明确有机物料的施用对糙米Hg积累的影响，对于Hg污染稻田的安全利用具有重要的指导意义。本研究采用盆栽实验，设置等量（3%，w/w）的油菜秸秆、猪粪和水稻秸秆生物炭，对比分析3种有机物料的施用对水稻产量及其对Hg在稻田系统的迁移转化的影响。结果表明，3种有机物料的施用均显著提高了水稻产量，但对土壤Hg甲基化和糙米Hg的积累影响则并不一致。油菜秸秆、猪粪和水稻秸秆生物炭处理下水稻产量分别提高17.6%、33.0%和39.9%。与相同水平土壤Hg处理相比，施用猪粪提高了土壤Hg的生物有效性，促进了土壤MeHg的生成，提高了糙米THg的富集系数，使糙米THg和MeHg的含量分别提高了34.5%和30.3%；施用油菜秸秆降低了土壤Hg的生物有效性，抑制了土壤Hg甲基化过程和水稻对Hg的富集，糙米THg和MeHg的含量分别降低了34.6%和36.2%；施用水稻秸秆生物炭降低了土壤Hg生物有效性和糙米THg的富集系数，糙米THg和MeHg的含量分别降低了46.9%和48.4%。因此，在Hg污染稻田中应慎重施用猪粪，可选择施用水稻秸秆生物炭和油菜秸秆，达到提高产量和阻控糙米Hg积累的双重效果。     

葫芦岛锌厂周围蜘蛛体内的汞含量及分布

以葫芦岛锌厂周围草地中的蜘蛛为研究对象,研究了汞在蜘蛛体内的含量及分布规律。结果表明,蜘蛛体内汞含量范围为6.72～185.01ng·g^-1,平均60.19ng·g^-1,远高于对照地区蜘蛛。不同采样点蜘蛛体内汞含量之间存在较大差异,距离锌厂远近对蜘蛛汞含量影响明显。蜘蛛体内总汞含量、头胸部及腹部汞含量分别同蜘蛛体重、对应器官重量之间呈显著负相关关系。蜘蛛不同器官中汞含量差异显著,表现出头胸部〉足〉腹部的规律。但是同其他昆虫相比,蜘蛛对汞的富集程度并不明显。     

天津大沽排水河沉积物典型持久性有机污染物的分布特征与来源解析

分别使用气相色谱质谱仪和气相色谱仪对2010年5月采集的天津市大沽排水河8个沉积物样的16种多环芳烃（PAHs）和7种有机氯农药（OCPs）进行了调查,结果表明,沉积物中PAHs的总含量范围为370～5607ng·g-1,平均浓度为2041ng·g-1,OCPs的总含量范围为42.2～680ng·g-1,平均浓度为222ng·g-1。对其组成特征及来源进行了分析,结果表明,沉积物中PAHs主要以3～4环为主,5～6环较少,沉积物中PAHs主要来自化石燃料的燃烧或交通源贡献,以及少量石油产品的输入。滴滴涕（DDT）及其代谢产物的含量明显低于林丹类物质（HCHs）,HCHs有新的输入,DDT没有新的输入,其降解方式主要是厌氧降解。     

胶州湾东岸表层沉积物中多氯联苯的分布特征及风险评价

分别于2009年春季（4月）、夏季（8月）、秋季（10月）、冬季（2010年1月）采集胶州湾东岸海域12个站位表层沉积物样品,参照美国EPA标准方法及采用气相色谱质谱联用（GC/MS）技术对表层沉积物中多氯联苯含量进行分析测定,同时对沉积物中多氯联苯的污染程度、年度分布特征、污染来源进行了研究。结果表明,胶州湾东岸表层沉积物中多氯联苯总量年度平均值较低,在10.39~22.26 ng.g-1之间,但各站点含量变化幅度较大,在1.84~105.22 ng.g-1之间;不同监测季节多氯联苯含量有明显差别,各海域总体含量为夏季〉秋季〉冬季〉春季,整体上呈现出由北向南逐渐降低的趋势,各调查海域含量是李村河〉海泊河〉石老人浴场。生态风险值、效应含量标准法以及毒性当量法评价结果表明,胶州湾东岸表层沉积物总体潜在风险不高,未对生态造成严重影响,但是李村河表层沉积物处于中度污染水平,应当引起关注。     

沘江流域耕地土壤重金属分布及生态风险评价

地处兰坪铅锌矿下游的沘江流域土壤重金属污染问题倍受关注。本文在沘江流域采集了35个耕地土壤样品,分析测定了砷、铜、锌、镉、铅、汞6种重金属污染物累积量,并应用内梅罗综合污染指数法及Hacanson潜在生态风险指数法,对耕地土壤污染状况及生态风险进行评价。结果表明:(1)沘江流域沿岸耕地重金属铅、锌、镉累积量相对处于极高水平,均值分别为1 146.97、579.15、4.85 mg·kg~(-1),污染十分严重;砷的累积量也较大,均值为26.85 mg·kg~(-1);铜、汞累积量较小,污染程度轻;(2)地统计分析结果表明,兰坪周边流域是土壤重金属砷、锌、铅、镉污染的一个主要点源污染源,而铜、汞污染没有显著点源污染源,均来自不同面源污染;(3)流域内梅罗指数均值为17.69(远大于3),存在极其严重重金属污染,同时综合潜在生态风险指数均值为773.38,有很强潜在生态风险。污染物贡献表现为镉铅锌砷汞铜;(4)沘江流域耕地土壤总体表现为水田重金属污染略高于旱地。     

崇明岛不同典型功能区表层土壤中有机氯农药分布及风险评价

通过测定崇明岛不同功能区（农场、普通农业区、城镇和自然保护区）表层土壤样品中的有机氯农药（OCPs）,对其残留现状、来源和潜在生态风险状况进行研究。结果表明,不同功能区土壤中OCPs残留水平为农场（39.2 ng.g^-1）〉普通农业区（8.0 ng.g^-1）〉城镇区（6.7 ng.g^-1）〉自然保护区（4.7 ng.g^-1）。与HCHs相比,DDTs残留污染要较高一些。不同功能地区土壤中HCHs没有新的污染源,而DDTs则仍有少量新污染源输入。农场（前进农场、富民农场）和城镇（堡镇长江边湿地）表层土壤中DDTs对鸟类和生物具有一定的生态风险,而普通农业区和自然保护区土壤中DDTs对该地区鸟类生态风险则较低。     

Biodegradation of Synthetic Dyes—A Review

The upper Great Egg Harbor River watershed in New Jersey’s Coastal Plain is urbanized but extensive freshwater wetlands are present downstream. In 2006–2007, studies to assess levels of total mercury (THg) found concentrations in unfiltered streamwater to range as high as 187 ng/L in urbanized areas. THg concentrations were <20 ng/L in streamwater in forested/wetlands areas where both THg and dissolved organic carbon concentrations tended to increase while pH and concentrations of dissolved oxygen and nitrate decreased with flushing of soils after rain. Most of the river’s flow comes from groundwater seepage; unfiltered groundwater samples contained up to 177 ng/L of THg in urban areas where there is a history of well water with THg that exceeds the drinking water standard (2,000 ng/L). THg concentrations were lower (<25 ng/L) in unfiltered groundwater from downstream wetland areas. In addition to higher THg concentrations (mostly particulate), concentrations of chloride were higher in streamwater and groundwater from urban areas than in those from downstream wetland areas. Methylmercury (MeHg) concentrations in unfiltered streamwater ranged from 0.17 ng/L at a forest/wetlands site to 2.94 ng/L at an urban site. The percentage of THg present as MeHg increased as the percentage of forest + wetlands increased, but also was high in some urban areas. MeHg was detected only in groundwater <1 m below the water/sediment interface. Atmospheric deposition is presumed to be the main source of Hg to the wetlands and also may be a source to groundwater, where wastewater inputs in urban areas are hypothesized to mobilize Hg deposited to soils.     

Wet deposition of methyl mercury in northwestern Ontario compared to other geographic locations

Concentrations of methyl mercury (MeHg) and total mercury (THg) in precipitation were measured at the Experimental Lakes Area (ELA), a remote field station in northwestern Ontario. We found that precipitation was a source of both MeHg and THg to boreal ecosystems, but at lower rates than in industrialized regions of North America and Scandinavia. MeHg concentrations in precipitation ranged from 0.010 to 0.179 ng L^?1 and were highest when events originated west of the ELA. THg concentrations in precipitation ranged from 0.95 to 9.31 ng L^?1 and were highest when the events came from the southeast. There was no relationship between THg and MeHg over time in precipitation. Inputs of both MeHg and THg to ecosystems were highest during summer months.     

Influence of the Forest Canopy on Total and Methyl Mercury Deposition in the Boreal Forest

Atmospheric mercury deposition by wet and dry processes contributes mercury to terrestrial and aquatic systems. Factors influencing the amount of mercury deposited to boreal forests were identified in this study. Throughfall and open canopy precipitation samples were collected in 2005 and 2006 using passive precipitation collectors from pristine sites located across the Superior National Forest in northern Minnesota, USA. Samples were collected approximately every 2 weeks and analyzed for total (THg) and methyl mercury (MeHg). Forest canopy type and density were the primary influences on THg and MeHg deposition. Highest THg and MeHg concentrations were measured beneath conifer canopies (THg mean?=?19.02 ng L^?1; MeHg mean?=?0.28 ng L^?1) followed by deciduous throughfall (THg mean?=?12.53 ng L^?1; MeHg mean?=?0.19 ng L^?1) then open precipitation (THg mean?=?8.19 ng L^?1; MeHg mean?=?0.12 ng L^?1). The greater efficiency of conifers at scavenging THg and MeHg from the atmosphere may increase the risk of mercury related water quality issues in conifer-dominated systems.     

Effects of plant rhizosphere on mercury methylation in sediments

Purpose  

This research investigates the effects of different plant species on Hg methylation rates, examines the difference in mercury (Hg) methylation rates in the plant rhizospheres, and shows the trend in methylmercury (MeHg) content of sediment in the Second Songhua River (SSR) of China, thereby providing the basis for estimating the ecological risk of this area.     

Influence of Sediment Preservation on Total Mercury and Methylmercury Analyses

Estuarine and riverine sediments from fourlocations showing different sediment structures wereanalysed as fresh, thawed and lyophilised samples fortotal mercury (TotHg) and methylmercury (MeHg)concentrations, and results were compared to addresseffects of sample preservation on Hg speciation. TotHg was measured by cold vapour atomic absorptionspectrometry (CVAAS). MeHg was isolated bydistillation and ion-exchange and analysed by coldvapour atomic fluorescence spectrometry (CVAFS) afterpreconcentration on a gold trap. No loss of TotHg norMeHg due to lyophilisation was found. Concentrationsof TotHg and MeHg respectively ranged from 92 to 267ng g^-1 dw and 1.1 to 2.9 ng g^-1 dw in freshsamples, from 94 to 215 ng g^-1 dw and 1.1 to 2.8ng g^-1 dw in thawed samples, and from 100 to 256ng g^-1 dw and 1.2 to 3.1 ng g^-1 dw inlyophilised samples. Lyophilised samples showedbetter homogeneity and better MeHg analysisreproducibility compared with wet samples.     

Evaluation of sediment capping effectiveness in Hyeongsan River for in-situ management of total mercury and methylmercury contamination

Journal of Soils and Sediments - In this study, the effectiveness of in situ sediment capping was investigated as a remediation option for total mercury (THg) and methylmercury (MeHg) in the...     

Mercury Concentrations in Lake Sediments – Revisiting the Predictive Power of Catchment Morphometry and Organic Matter Composition

Lake sediments are a potential source of mercury (Hg) for aquatic biota. Here, we investigated the predictive power of (a) key parameters for lake catchment morphometry and (b) organic matter composition of sediments in an effort to account for observed variations of total (THg) and methyl (MeHg) mercury concentrations in lake sediments. Using regression models we demonstrate that the morphometric parameters lake depth as well as inclination of catchment soils and lake bottoms can significantly predict variations of THg concentrations, but not MeHg, at profundal lake sediments. Although THg and MeHg concentrations in sediments could not be predicted by specific organic matter sources, as elucidated by atomic C/N ratios, our data suggest that wetland-derived total organic carbon (TOC) contained less THg concentrations than TOC derived from mostly forested watersheds. However, TOC concentrations could significantly predict MeHg concentrations and the proportion of methylated Hg at all sediment stations. Finally, from an ecotoxicological point of view, we propose that concentrations of TOC at surface lake sediments, rather than parameters of catchment morphometry, may predict dietary sources of MeHg for benthic consumers and consequently perhaps for organisms at higher trophic levels.