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1.
Total mercury (Hg) and methylmercury (MeHg) were analyzed in near surface sediments (0-2 cm) and biota (zooplankton, macro-invertebrates, finfish) collected from Narragansett Bay (Rhode Island/Massachusetts, USA) and adjacent embayments and tidal rivers. Spatial patterns in sediment contamination were governed by the high affinity of Hg for total organic carbon (TOC). Sediment MeHg and percent MeHg were also inversely related to summer bottom water dissolved oxygen (DO) concentrations, presumably due to the increased activity of methylating bacteria. For biota, Hg accumulation was influenced by inter-specific habitat preferences and trophic structure, and sediments with high TOC and percent silt-clay composition limited mercury bioavailability. Moreover, hypoxic bottom water limited Hg bioaccumulation, which is possibly mediated by a reduction in biotic foraging, and thus, dietary uptake of mercury. Finally, most biota demonstrated a significant positive relationship between tissue and TOC-normalized sediment Hg, but relationships were much weaker or absent for sediment MeHg. These results have important implications for the utility of estuarine biota as subjects for mercury monitoring programs.  相似文献   

2.
Anthropogenic mercury pollution was studied in Kastela Bay (Croatia), 10 years after chloralkaline plant (PVC) stopped production. The concentration of total mercury determined in sediments which are composed mainly of calcite and quartz, are in the range 14,280-30,400 ng/g. The values are higher than reported in the literature for Elbe and Seine estuaries and also above 25,000 ng/g used for criterion in remediation project in Minamata Bay. The concentration of methylmercury 6.05-36.74 ng/g are typical for slightly to highly contaminated estuarine sediments. The low ratio of methylmercury to total mercury found in sediments of Kastela Bay is in the range 0.04-0.18%. It can be explained that in this region predominate conditions which do not promote in-situ methylation. Sediments were found to be highly anoxic. Concentrations of total mercury in unfiltered surface waters are in the range 69-145 ng/l and in unfiltered bottom waters in the range 230-1,418 ngl(-1). High concentrations found in bottom waters suggest that either resuspension or partial dissolution of sediments takes place. An experiment performed on filtered and unfiltered waters showed that about 85% of total mercury in surface water and almost 100% in bottom water was retained on 45 microm filters. To demonstrate contrasts, two pristine estuaries from norths and south Europe were studied. Silicious sediments of Ore estuary (Sweden) and calcareous sediments of Krka estuary (Croatia) have total mercury concentrations close to accepted background level. The ratio of methylmercury to total mercury is < or = 1% in all samples with one exception. The highest observed ratio (2.70%) was in the surface sediment from E2 station in Krka estuary measured in March 2000. This location is suitable for studying methylmercury formation in pristine environment.  相似文献   

3.
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   

4.
Selenium’s (Se) protective effects against mercury (Hg) toxicity have been demonstrated; however, this is seldom considered in health assessments, where dietary exposure is still evaluated by Hg concentration alone. Se:Hg ratios and selenium health benefit values (Se HBVs) offer a more comprehensive seafood safety model. Here we describe total mercury (THg), methylmercury (MeHg) and Se concentrations in fish from a Hg-polluted estuary. Spatial variation in THg, MeHg and Se was evident, though all regions maintained Se:Hg ratio values >1. Se HBV varied between regions and in one region mean negative values (−5.17) were evident. This study provides the first evidence that quoting a single all-encompassing Se HBV is not appropriate when species demonstrate strong site fidelity. It highlights the need for research into Se–Hg relationships in environments with established Hg pollution and reinforces the assertion that Se concentration be considered in assessments of human health risk to Hg exposure.  相似文献   

5.
Mercury（Hg） is well known as one of the most toxic elements to man.The coastal environments adjacent to industrial areas are reported to often be contaminated with mercury.Mercury becomes more toxic in the form of methylmercury（Me-Hg） which is converted from inorganic mercury in aqueous systems by microbial activity and can bio-magnify through the food chain.A simple method for the determination of total mercury and methylmercury in sediments was optimized by slightly modifying an old method using the direct mercury analyzer technique.Core sediment samples from Thane Creek,Mumbai,India were collected and analysed for total mercury and methylmercury.The Hg concentration in the creek varied between 0.54 to 16.03 μg g~（-1） while Me-Hg concentrations ranged between0.04 to 1.07 μg g~（-1）.In surface sediment,mercury concentrations ranged from 4.33 μg g~（-1） to 12.16μg g~（-1）.Total organic carbon content was found to be around 2 percent in different layers of the sediments.The enrichment factors,which indicate the extent of pollution in sediments,were estimated to range from 26 to 50 at different locations in the creek.Lithogenic and anthropogenic concentrations of mercury in the creek were also determined to compare the impact of anthropogenic and natural sources.Anthropogenic inventories were about 5-70 times more in concentration than the lithogenic in the different core sediments.  相似文献   

6.
Mercury concentrations in surface intertidal sediments from estuarine and coastal environments of the Northeastern Irish Sea are reported. This region has two inputs of mercury contaminated effluents from chlor-alkali factories, and localized mercury contamination of sediments fairly similar to that reported for the Rhine has been found in the Wyre estuary. The present results for the Mersey estuary agree well with others reported in the lierature. Coastal sediments are much less contaminated than the estuarine deposits, and in all the environments studied strong correlations between mercury concentration, total organic carbon and < 63 μm grainsize fraction contents have been found.  相似文献   

7.
Determinations of dissolved reactive and total dissolved mercury, particulate and sedimentary mercury, dissolved organic carbon (DOC), particulate organic carbon (POC) and suspended particulate matter (SPM) have been made in the estuary of river Douro, in northern Portugal. The estuary was stratified by salinity along most of its length, it had low concentrations of SPM, typically <20 mg dm(-3), and concentrations of DOC in the range <1.0-1.8 mg dm(-3). The surface waters had a maximum dissolved concentration of reactive mercury of about 10 ng dm(-3), whereas for the more saline bottom waters it was about 65 ng dm(-3). The surface waters had maximum concentrations of total suspended particulate mercury of approximately 7 microg g(-1) and the bottom waters were always <1 microg g(-1). Concentrations of mercury in sediments was low and in the range from 0.06 to 0.18 microg g(-1). The transport of mercury in surface waters was mainly associated with organic-rich particulate matter, while in bottom waters the dissolved phase transport of mercury is more important. Lower particulate organic matter, formation of chlorocomplexes in more saline waters and eventually the presence of colloids appear to explain the difference of mercury partitioning in Douro estuarine waters.  相似文献   

8.
富营养化对贵州红枫湖水库汞形态和分布特征的影响   总被引：6，自引：1，他引：5  
通过对贵州省红枫湖水库中各种汞形态的空间分布及季节变化的研究,探讨了富营养化对各种汞形态分布特征的影响.红枫湖湖水总汞浓度在2.5-13.9ng/L之间,平均值为6.9ng/L.红枫湖水库中汞浓度的空间分布和季节变化均严重受到人为汞污染源的干扰.水体中汞在颗粒态和溶解态之间的分配,主要受内源有机质以及氧化还原条件的影响.由于水华现象,春季后五采样点大量繁殖的藻类吸附了大量的汞,从而改变了汞在水库中的分配和迁移.藻类的生长对水体中溶解气态汞浓度分布也有显著的影响.在夏季,总甲基汞和溶解态甲基汞在水体中的垂直分布表明:在富营养化较严重的后五采样点,水体中升高的甲基汞主要是由于水体中汞的甲基化过程;而在富营养化特征不明显的大坝,水体中升高的甲基汞主要来自沉积物甲基汞的释放.红枫湖水体中各种汞形态的分布特征表明,富营养化对汞的迁移转化影响显著,尤其是汞的甲基化过程.水体富营养化为汞的甲基化提供了有利条件,给水生生态环境及人体健康带来了潜在的威胁.  相似文献   

9.
Guanabara Bay, in Rio de Janeiro state, is impacted by organic matter, oil and heavy metals. The present study evaluated the total mercury (THg) and methylmercury (MeHg) concentrations and the MeHg to THg ratio (%MeHg) in water samples from different points of the bay and in 245 organisms of three different trophic levels sampled between 1990 and 2000. Dissolved mercury concentration in estuarine water samples ranged from 0.72 to 5.23 ngl(-1). THg and MeHg in mussel, ranging from 11.6 to 53.5 microg THg kg(-1) wet wt. and 4.5-21.0 microg MeHg kg(-1) wet wt., varied according to sampling point and water quality. Planktivorous fish and mussel presented similar MeHg concentrations, meanwhile THg in planktivorous fish were lower than in mussel. Carnivorous fish showed higher THg and MeHg concentrations (199.5 +/- 119.3, 194.7 +/- 112.7 microg kg(-1) wet wt. respectively) than organisms from other feeding habits and lower trophic levels. There was a significant difference in the %MeHg among trophic levels: mussel presented lower MeHg percentage (33%) than planktivorous fish (54%) and carnivorous fish (98%).  相似文献   

10.
Mercury(Hg) is a global pollutant and can be accumulated in the food chain, posing exposure risks to humans. In this study, rice plants and corresponding rhizosphere soil samples were collected from a watershed of the Wawu River Basin that is heavily impacted by historic Hg mining and retorting activities. Total mercury(THg)and methylmercury(MeHg) in rice grains, as well as other tissues and soil samples, were measured. Five soil Hg fractions, as well as soil parameters, were also determined.The results show that the average concentrations of THg and MeHg in rice grains were 14 ± 7.0 lg kg-1 and7.2 ± 4.0 lg kg-1. Soil organic-bound(Hg-o) and strong complex-bound(Hg-s) were the main Hg fractions,accounting for 44% of the total. To estimate the Hg–ligand interaction in the soils, soil-N/Hg(R = 0.451, p \ 0.05),-S/Hg(R = 0.372, p \ 0.1), and-OM/Hg ratio(R = 0.320,p \ 0.5) with MeHgsoil were observed with significant positive correlations, indicating that the formation of Hg–OM, Hg–N–OM or Hg–S–OM complexes could prevent Hg(II) from methylation in soils. The significant positive correlations of the-N/Hg ratio,-S/Hg ratio and-OM/Hg ratio with MeHg in rice tissues suggested that Hg methylation and MeHg demethylation occurred throughout the rice paddy ecosystem. The estimated MeHg daily intake(EDI) was 0.075 ± 0.041 lg kg-1 bw d-1 and was lower than the RfD level of 0.1 lg kg-1 bw d-1 recommended by the US EPA. However, approximately 29% of the hazardous index(HI) of MeHg in grain exceeded 1, posing a potential threat to local populations, particularly pregnant women and children.  相似文献   

11.
This paper reports on mercury (Hg) concentrations in different tissues (liver, muscle, kidney, blubber and brain) of harbour porpoises Phocoena phocoena found dead in the Black Sea between 1997 and 1999, mainly bycaught in fishing nets (n = 79). Total Hg and organic Hg (MeHg) were determined. The main factor affecting Hg accumulation was, as expected, age, with MeHg concentration increasing with age. Accumulation of high concentrations of inorganic Hg in the liver was probably due to a slow demethylation process implying the formation of tiemannite (HgSe). In older adults, liver concentrations reached 35 microg g(-1) dry weight ('ppm') total Hg and 3 microg g(-1) dw MeHg. A geographical comparison with existing data from other regions showed a generally low Hg contamination of Black Sea porpoises, one order of magnitude lower than, e.g. in the North Sea.  相似文献   

12.
Yu X  Li H  Pan K  Yan Y  Wang WX 《Marine pollution bulletin》2012,64(8):1699-1704
Surface sediments and sediment cores collected from the Pearl River Estuary (PRE) were analyzed for total mercury (THg) concentrations and speciation using a sequential extraction method. The mobility of Hg in sediments was also assessed using a series of single extraction methods. The surface sediments from the PRE showed slightly elevated levels of Hg, with concentrations ranging from 109 to 453 ng/g. The vertical profile of THg in sediment cores indicated an accelerated input of Hg over the past decades. The organo-chelated and strong-complexed Hg species were the dominant Hg species in the sediments, while the more mobile phases of Hg made up less than 0.5% of THg. Less than 10% of the Hg in the sediments was extracted by single extraction, depending on the extractant employed. Significant relationships were found between the total organic carbon and THg, geochemical speciation, and extractability, indicating the important role of organic matter in controlling the distribution, mobility, and bioavailability of Hg in sediments.  相似文献   

13.
Present study has continued the investigation on distribution of mercury in estuarine sediments of Patos Lagoon which began whilst assessing the after-effect of enormous accidental discharge of sulfuric acid into the estuary. An attempt to evaluate the contribution of anthropogenic effluents on mercury pollution in sediments was undertaken. The effluents from Rio Grande City sewages were categorized into four groups based on their sources. Comparison of mercury concentrations from those, indicated that domestic effluent was prevalent. Apparent geographic controls of effluent locations enriched in mercury on zones of polluted estuarine sediments were also revealed. Insufficient control on waste collecting and absence of sewage treatment are considered the principal causes of mercury pollution in estuarine sediments.  相似文献   

14.
The focus of this work is to explore the use of the netted whelk, Nassarius reticulatus (L.), as an indicator of mercury (Hg) contamination, by assessing the concentration of Hg in the sediments and in the whelk along the entire Portuguese coast. Total Hg concentrations ranged from below the detection limit (0.01 ng absolute mercury) up to 0.87 mg kg(-1) dry weight (dwt) in sediments and between 0.06 and 1.02 mg kg(-1) (dwt) for organisms, with no significant differences between males and females. Although organic mercury was not detected in the sediments, it represented, on average, 52% of the total Hg in the whelk tissues, and as high as 88% in some cases, suggesting mercury accumulation from dietary intake. Significant negative correlations were found between the total Hg concentrations in the sediments and the log(10) of Hg concentrations in whelk tissues males (r=-0.64; P<0.01) and females (r=-0.52; P<0.01) indicating that the species is a poor indicator of Hg contamination. Nevertheless, since the highest concentrations of organic mercury in the whelk tissues were found in the least contaminated areas, this species must be highly relevant in the trophic web, namely on the possible biomagnification of mercury. The high dietary mercury accumulation from feeding on carrion and the low bioavailability of mercury to whelks in estuarine sediments may be the basis of the mercury accumulation pattern in N. reticulatus.  相似文献   

15.
We relate fish biological and ecological characteristics to total and organic mercury concentrations to determine whether accumulation is influenced by trophic level, Hg concentration in the diet, and vertical distribution. Levels of total mercury and methylmercury were determined in the muscle tissue of eight species of fish: Pagellus acarne, Trachurus picturatus, Phycis phycis, P. blennoides, Polyprion americanus, Conger conger, Lepidopus caudatus and Mora moro, caught in the Azores. All such fishes are commercially valuable and were selected to include species from a wide range of vertical distributions from epipelagic (<200 m) to mesopelagic (>300 m) environments. Methylmercury was the major form accumulated in all species, comprising an average of 88.1% of total mercury. Concentrations of mercury (total and methylmercury) increased with age, length and weight. Based on data from other studies, mercury concentrations in fish diet were estimated. Mercury levels in food ranged from 0.08 to 0.32 ppm, dry weight. Hg concentrations in the food and in muscle tissue from different species were positively correlated. Total Hg levels in the muscles were approximately nine times those estimated in food. Total mercury concentrations in muscle were positively correlated with both trophic level and median depth. Such enhanced mercury bioaccumulation in relation to depth appears to be determined primarily by concentrations in food and ultimately by water chemistry, which controls mercury speciation and uptake at the base of the food chain.  相似文献   

16.
运用金汞齐-冷原子荧光光谱法(CVAFS)和气相色谱技术(GC),对贵州省草海不同水文季节(枯水期和丰水期)表层水中汞的各种赋存形态,包括总汞(HgT)、溶解态汞(HgD)、活性汞(HgR)、颗粒态汞(HgP)、总甲基汞(MeHgT)、溶解态甲基汞(MeHgD)和颗粒态甲基汞(MeHgP)以及沉积物间隙水剖面中的溶解态总汞和甲基汞含量进行了测定.结果显示:草海表层水体总汞浓度为1.7-9.0ng/L,活性汞浓度为0.06-1.4ng/L,总甲基汞浓度为0.11-0.67ng/L.沉积物间隙水中溶解态汞浓度为8.6-39.6ng/L,溶解态甲基汞浓度为0.11-4.9ng/L.实验数据表明,草海湖水以溶解态汞为主,其占总汞的比例为枯水期87%,丰水期51%,溶解态汞与总汞呈显著相关(丰水期P<0.01;枯水期P<0.05),颗粒态汞与总汞也呈显著相关(丰水期P<0.01;枯水期P<0.05).溶解态甲基汞与总甲基汞呈显著相关(丰水期P<0.01;枯水期P<0.05),表明溶解态甲基汞控制总甲基汞的分布.沉积物间隙水溶解态汞与溶解态甲基汞浓度明显高于上覆水体,表明沉积物为草海湖水中汞的一个重要来源.  相似文献   

17.
The occurrence of plutonium isotopes derived from the Windscale reprocessing facility discharges and weapons test fallout in intertidal sediments of the Wyre estuary, northwest England, is reported. Windscale plutonium appears to be slowly transported to the estuary in association with sedimentary material, and its distribution in surface and buried sediments is controlled by the variations in organic matter content of the sediments and/or their grain size characteristics. Results from chemical leaching experiments suggest that very little plutonium is ion exchangeable or in humic substances, but it is in other organic and Fe/Mn hydrous oxide fractions of the sediments. Plutonium shows a similar depositional behaviour to mercury which enters the Wyre directly in local industrial discharges.  相似文献   

18.
《Marine pollution bulletin》2014,88(1-2):388-395
Distribution of sedimentary mercury in the Southern Baltic was investigated. Sediment samples were collected from the Southern Baltic in the period from 2009 to 2011, and concentrations of sedimentary total mercury (average 102 ng/g, range 5.8–225 ng/g) and methyl mercury (average 261 pg/g, range 61–940 pg/g) were measured in the manner that the influence of both patchiness and seasonal changes were assessed. Moreover, sedimentary mercury extracted with organic solvent- the so-called organic mercury was also analyzed (average 425 pg/g, range 100–1440 pg/g). There is a statistically significant dependence between organic mercury and both methyl mercury and total mercury concentrations in the sediments. Methyl mercury contribution to total mercury varied from 0.12% to 1.05%, while organic mercury contributed to 2% of total concentration on average. The area studied, although mercury concentrations exceed threefold the geochemical background, can be regarded as moderately contaminated with mercury, and methylmercury.  相似文献   

19.
为了解贵州高原水库浮游植物中汞和甲基汞的分布特征及浮游植物对汞及甲基汞的富集特点,于2012年12月对贵州省的5座高原水库中浮游植物和汞形态进行采样调查.研究结果表明:冬季贵州高原水库浮游植物群落主要是由硅藻组成,5座水库浮游植物丰度有明显差异.百花湖大坝处浮游植物丰度最高,为29.05×104cells/L;三板溪水库浮游植物丰度最低,仅为0.49×104cells/L.浮游植物中总汞和甲基汞的浓度分别在29.29~277.07 ng/g和1.12~10.93 ng/g之间,总汞含量以百花湖岩脚寨最高,甲基汞含量以百花湖大坝最高.总汞和甲基汞在浮游植物中的生物富集系数分别在1.42×104~9.78×104和3.10×104~4.43×105之间.在浮游植物富集无机汞及甲基汞的系数中,百花湖中浮游植物对无机汞生物富集系数最高,而红枫湖中浮游植物对甲基汞的生物富集系数最高.浮游植物种类组成不同对汞及甲基汞的生物富集有影响.浮游植物中的总汞与水体中的总汞、甲基汞和溶解态甲基汞都存在显著的相关关系,浮游植物中的甲基汞与水体中的总汞及甲基汞不存在显著相关性.甲基汞在浮游植物中富集不是简单的吸收,存在着影响甲基汞在浮游植物中富集的其它因素.浮游植物中的甲基汞与水体富营养化环境因子(透明度、总氮、硝氮)均呈负相关关系,表明水体富营养化的程度不同对浮游植物中的甲基汞浓度有影响.  相似文献   

20.
The relationships between total mercury (Hg) concentration and stable nitrogen isotope ratio (δ15N) were evaluated in Mullus barbatus barbatus and M. surmuletus from the Mediterranean Sea and M. barbatus ponticus from the Black Sea. Mercury concentration in fish muscle was six times higher in the two Mediterranean species than in the Black Sea one for similar sized animals. A positive correlation between Hg concentration and δ15N occurred in all species. Increase in Hg concentration with δ15N was high and similar in the two Mediterranean fishes and much lower in the Black Sea species. Since this was neither related to trophic level difference between species nor to methylmercury (MeHg) concentration differences between the north-western Mediterranean and the Black Sea waters, we suggested that the higher primary production of the Black Sea induced a dilution of MeHg concentration at the base of the food webs.  相似文献   

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