Long-term changes in mercury concentrations in fish from the middle Savannah River

Total mercury levels were measured in largemouth bass (Micropterus salmoides), "sunfish" (Lepomis spp.), and "catfish" (primarily Ameiurus spp. and Ictalurus punctatus) from 1971 to 2004 in the middle Savannah River (river km 191 to 302), which drains the coastal plain of the southeastern U.S. Total mercury concentrations were higher in largemouth bass (overall mean of 0.55 mg/kg from 1971 to 2004), a piscivorous (trophic level 4) species than in the other taxa (means of 0.22-0.26 mg/kg), but temporal trends were generally similar among taxa. Mercury levels were highest in 1971 but declined over the next 10 years due to the mitigation of point source industrial pollution. Mercury levels in fish began to increase in the 1980s as a likely consequence of mercury inputs from tributaries and associated wetlands where mercury concentrations were significantly elevated in water and fish. Mercury levels in Savannah River fish decreased sharply in 2001-2003 coincident with a severe drought in the Savannah River basin, but returned to previous levels in 2004 with the resumption of normal precipitation. Regression models showed that mercury levels in fish changed significantly over time and were affected by river discharge. Mercury levels in Savannah River fish were only slightly lower in 2004 (0.3 to 0.8 mg/kg) than in 1971 (0.4 to 1.0 mg/kg) despite temporal changes during the intervening years.     

Binding of mercury in soils and attic dust in the Idrija mercury mine area (Slovenia)

Total Hg concentrations and Hg speciation were determined in soils and attic dust in a 160 km2 area around Idrija mercury mine. Attic dust as well as a sample of soil was collected at 100 locations. Mercury phases were separated into cinnabar and non-cinnabar compounds via a thermo-desorption technique. The amount of the non-cinnabar fraction is important since it is potentially bioavailable and results are needed for further risk assessment studies. The concentrations of Hg in attic dust are many times higher than in surrounding soils and the attic dust/soil ratio changes with distance. The highest concentration ratios were identified at the greatest distance from the source of pollution and the lowest close to the source of pollution. This confirms the impact of air emissions on the wider area around Idrija. Furthermore the spatial mercury distribution in the attic dust shows that the influence of atmospheric emissions caused by the Idrija smelter resulted in impacts on the environment on a regional scale. The portions of non-cinnabar compounds increase with distance from the mercury source in both sampling media. Non-cinnabar fractions were found to be enriched in distant areas where fine grained material was deposited. There were two different transport mechanisms of dust particles and gaseous Hg(0) during the mercury production period. Obviously coarse grained particles, with mostly cinnabar-bound Hg settled in the immediate vicinity of the smokestack of the smelter, whereas the fine grained fraction could be dispersed further ahead. This is represented by the percentage of cinnabar-bound Hg in attic dust and soil decreasing with distance from the smelter. Gaseous Hg(0) is probably bound to fine and ultrafine aerosols with longer residence time against deposition. The consequence is that fine grained material with Hg2+ and Hg0 prevails in remote localities and is bound in soils and dust with matrix and organic matter as non-cinnabar mercury compounds. The distributions of mercury species in attic dust and soils along the Idrijca River show that in the region from Idrija to Spodnja Idrija the portions of cinnabar and non-cinnabar are about equal, while in the upper and in the lower Idrijca valley non-cinnabar bound mercury prevails. The applicability of attic dust for tracing the mercury halo in the Idrija area was successfully shown.     

A multi-element profile of housedust in relation to exterior dust and soils in the city of Ottawa, Canada

This paper presents multi-element profiles of indoor dust versus exterior soils and dusts from 50 residences located in 10 neighborhoods across Ottawa, the capital city of Canada. Mercury concentrations were determined using nitric-sulphuric acid digestion and cold vapor AAS. Concentrations of 31 other elements were determined using nitric-hydrofluoric acid digestion and ICP-MS. Comparisons of household dust, garden soil and street dust at the individual residence scale and at the community scale were based on a consistent 100-250-microm particle size fraction. Results showed housedust samples to contain significantly higher concentrations of many key elements, including lead, cadmium, antimony and mercury, than either street dust or garden soil samples. Also, housedust profiles revealed a distinct multi-element signature in relation to exterior dust and soil samples. Interestingly, garden soil contained higher concentrations of aluminum, barium and thallium than either house or street dust. Geometric mean concentrations (mg/kg) of these elements in household dust/garden soil were: lead 233/42; cadmium 4.42/0.27; antimony 5.54/0.25; mercury 1.728/0.055; aluminum 24281/55677; barium 454/763; and thallium 0.14/0.29. Street dust contained lower geometric mean concentrations than garden soil for 23 out of a total of 32 elements. In general, indoor/outdoor concentration ratios varied widely from one element to another, and from one residence to another within the community. In the case of Ottawa, which is a city with a low concentration of heavy industries, it would be difficult-to-impossible to accurately predict indoor dust concentrations based on exterior soil data. It is concluded that dust generated from sources within the house itself can contribute significantly to exposures to certain elements, such as lead, cadmium, antimony and mercury.     

Mercury in the River Nura and its floodplain, Central Kazakhstan: II. Floodplain soils and riverbank silt deposits

A unique and serious case of mercury pollution has occurred in the River Nura and its floodplain in Central Kazakhstan, where mercury-rich wastewater from an acetaldehyde plant was discharged largely without treatment for several decades. In the river, the mercury became associated with millions of tonnes of power station fly ash, forming a new type of deposit known as 'technogenic silt'. During spring floods these highly contaminated silts are transported downstream and are dispersed over the floodplain, leading to widespread contamination of the land. A detailed survey of the floodplain was carried out to investigate the extent of pollution and to assess the need for remediation. Total mercury concentrations in the topsoils of the floodplain ranged from near background levels to over 100 mg/kg. Mercury concentrations in river bank deposits were found to range from a mean of 73.3 mg/kg Hg in the most contaminated section of the river to a mean of 13.4 mg/kg Hg at a distance of 70 km downstream. Concentrations were lower than corresponding concentrations in the riverbed within the first 25 km from the source of the pollution, but thereafter they were significantly higher. The results show that over the past 30-40 years a large proportion of the contaminated sediments from the river was deposited on the 70 km of banks and in the floodplain below the pollution source. Topsoils of the floodplain and silt deposits located on or close to the river banks contain an estimated 53 t and 65 t of mercury respectively, with an additional 62 t in a small natural swamp which was formerly used as a waste disposal area. The contamination is serious but relatively localized, with > 70% of the total amount of mercury in topsoils and > 90% of mercury in river bank deposits located within 25 km from the source.     

Mercury contamination in the Yatsushiro Sea, south-western Japan: spatial variations of mercury in sediment

Mercury-contaminated effluent was discharged into Minamata Bay from a chemical plant over a 20-year period until 1965 (from 1958 to 1959, effluent was discharged into Minamata River), causing Minamata disease. In an effort to characterize the extent of the contamination in the Yatsushiro Sea, the vertical and horizontal distributions of mercury in sediment were investigated. Sediment was sampled at 62 locations in the southern part of the sea from 4 to 6 March 1996. In the lower layers of the long cores of sediment, the total amount of mercury was at a relatively uniform low concentration. We interpret these low values to represent the background concentration absent of anthropogenic influence. The background value thus estimated for the Yatsushiro Sea was 0.059 +/- 0.013 mg kg(-1) (mean +/- S.D., n = 51). The highest concentration in each sample ranged from 0.086 to 3.46 mg kg(-1) (mean, 0.57 mg kg(-1)). The higher values were obtained at stations near Minamata Bay and the Minamata River (the sources of the pollution). Concentrations decreased with distance from the source. An inspection of the vertical profiles of mercury concentration in cores suggested that the deposited mercury had not been fixed in sediment but had been transported, despite 30 years having past since the last discharge of contaminated effluent. At nine stations, extractable inorganic and organic mercury concentrations were determined differentially. Inorganic mercury is the predominant species in sediment and organic mercury comprising approximately 1% of the total.     

A preliminary study on mercury contamination to the environment from artisanal zinc smelting using indigenous methods in Hezhang County, Guizhou, China: Part 2. Mercury contaminations to soil and crop

Artisanal zinc smelting using indigenous method in Hezhang County, Guizhou, China has posed seriously environmental pollution to the local environment. Within less than 150 km2 area in Hezhang, a few metric tons of mercury were released into the atmosphere each year since 1989 due to artisanal zinc smelting, and the surface waters were seriously contaminated with mercury. For the first time, we investigated the mercury contamination to the local soil and crop compartments due to mercury emissions from artisanal zinc smelting activities in this area. Mercury distribution patterns in 5 soil profiles collected in artisanal zinc smelting area showed that the top soils were seriously contaminated with mercury. The soils from agriculture land close to the zinc smelting areas were also contaminated with mercury due to the deposition of mercury species that emitted from artisanal zinc smelting processes. Total mercury concentrations in top soils decrease exponentially with distance from the zinc smelting area. Corn plants that were cultivated in agriculture land close to the zinc smelting area were also contaminated with mercury. Mercury concentration in corn plant tissue increased in the order of grains相似文献   

Temporal and spatial trends of mercury in fish collected in the English-Wabigoon river system in Ontario, Canada

The First Nations communities of Grassy Narrows and Wabaseemong (Ontario, Canada) have been impacted by mercury pollution since the 1960s. This study was implemented with the objective of providing these communities with information on current mercury concentrations in their catch, in order to make appropriate fish consumption choices. A total of 851 fish samples, including Walleye, Northern Pike, Large-mouth Bass, and Whitefish, were collected from thirteen lakes and rivers. Total mercury was measured and the relationship between fish length, mercury concentration, and lake of origin were assessed. It was found that fish from most of the lakes exhibit a positive relationship between length and mercury accumulation. Mercury concentrations in fish collected from Clay Lake, closest to the original source of contamination, are higher than those from other lakes. Mercury concentrations have declined over the last 25 years but the gradient of contamination was still observed. Results were communicated to the communities for public health purposes.     

The influence of soil remediation on lead in house dust

Lead in house dust has long been recognized as a principal source of excess lead absorption among children at the Bunker Hill Superfund Site (BHSS) in northern Idaho. House dust lead concentration from homeowner's vacuum cleaner bags has been monitored since the epidemic of childhood lead poisoning in 1974. Geometric mean house dust lead concentrations decreased from >10000 mg/kg in 1974 to approximately 4000 mg/kg in 1975, in response to air pollution control initiatives at the defective primary lead smelter. After smelter closure, 1983 mean dust lead concentrations were near 3000 mg/kg and were most dependent on soil sources. Following emergency soil removals from public areas and roadsides and fugitive dust control efforts in the mid-1980s, house dust lead decreased by approximately 40-60% to 1200-1500 mg/kg. In 1992, a cleanup goal of 500 mg/kg dust lead community average, with no individual home exceeding 1000 mg/kg, was adopted. This goal was to be achieved by a combination of contaminated soil removals and fugitive dust control efforts throughout the 21 square mile BHSS. Continual reductions in house dust lead concentrations have been noted throughout the residential area soil cleanup. Geometric mean house dust lead concentrations averaged approximately 500-600 mg/kg from 1996 to 1999 and dropped below 500 mg/kg in 2000. Analysis of these data indicates that approximately 20% of the variance in dust lead concentrations is attributed to yard, neighborhood, and community soil lead concentrations. Since 1996, dust lead concentrations and dust and lead loading rates have also been measured by dust mats placed at entryways into the homes. Neighborhood soil lead concentrations, household hygiene, the number of adults living in the home, and the number of hours a child spends outdoors in summer explain approximately 26% of the variance in mat dust lead loading rates. It is estimated that post-remedial house dust lead concentrations will stabilize at 400-500 mg/kg, as compared to approximately 200 mg/kg in socio-economically similar background communities; the difference possibly attributed to residual soil concentrations (3-6 times background), recontamination of rights-of-way, tracking of non-residential mining district soils and dusts, fugitive dusts associated with the remediation, and residual structural or carpet dusts.     

Baseline levels of Hsp 70, a stress protein and biomarker, in halibut from the Cook Inlet region of Alaska

The levels of Hsp 70, a heat shock protein, was quantitatively determined in Pacific halibut, Hippoglossus stenolepis, from the Cook Inlet region in south central Alaska. A dot blot analysis using a monoclonal antibody for Hsp 70 was combined with a standard protein analysis to determine Hsp 70 levels in 26 samples from gills. The average Hsp 70 concentration was 4.6 micrograms/mg, with levels ranging from 2.2 to 14.5 micrograms/mg total protein. Mercury in gill tissue also was measured and, in the 26 samples, only three samples had concentrations of mercury (X = 0.10 mg/kg, range = 0.09-0.11) above the minimum detection level.     

Mercury in the River Nura and its floodplain, Central Kazakhstan: I. River sediments and water

The River Nura in Central Kazakhstan has been heavily polluted by mercury originating from an acetaldehyde plant. Mercury in the riverbed is mainly associated with power station fly ash, forming a new type of technogenic deposit. A systematic survey of the bed was carried out to establish the location, extent and nature of the contaminated sediments, and to evaluate the potential for sediment transport. The bed sediments were found to contain very high concentrations of mercury, particularly in the first 15 km downstream of the source of the pollution. Average total mercury concentrations in this section of the river are typically between 150 and 240 mg/kg, falling rapidly with increasing distance downstream. The estimated total volume of silts in the riverbed between Temirtau, the origin of the pollution, and Intumak Reservoir, located 75 km downstream, has been calculated as 463500 m3, containing an estimated 9.4 tonnes mercury. Forty-six percent of the total volume of contaminated silts containing almost 95% of the mercury are located in the upper 25 km of the river, however. The data clearly support the hypothesis that large quantities of polluted sediment are not transported long distances downstream but are removed from the aquatic environment in times of flood and deposited on the low-lying lands adjacent to the river. This process, however, does not stop mercury moving further downstream in the water column.     

Assessing the contribution of natural sources to regional atmospheric mercury budgets

Naturally mercury-enriched substrate is a long-lived source of mercury to the global atmospheric mercury cycle. Field flux chambers, laboratory gas exchange chambers and micrometeorological methods may be applied to estimate emissions from these sources. However, field chamber experimental design may affect the magnitude of the fluxes measured, and the laboratory chamber only provides a minimum estimate of flux. Many factors, such as mercury concentration and speciation in substrate, light, precipitation, and temperature, influence the emission of mercury from the substrate. Mercury concentration in the substrate is a dominant factor controlling emissions and may be used to predict emissions from regions of mercury enrichment. Mercury fluxes measured from three areas of natural enrichment and three areas with low levels of mercury enrichment are 1-5 orders of magnitude greater than the value applied to global belts of natural enrichment. Preliminary scaling of emissions from one of these areas and for western North America indicates that mercury enriched areas may be significant sources of mercury to the atmosphere, and that their contribution to regional and global atmospheric budgets needs to be reassessed.     

An inventory of historical mercury emissions in maritime canada: implications for present and future contamination

Mercury is a longstanding concern in Maritime Canada due to high levels of contamination in a number of fish and bird species. The recycled component of past releases of anthropogenic mercury may be a significant source of ongoing pollution in many areas. Historical information on mercury releases can be used to quantify past and present anthropogenic contamination. We present an inventory of historical mercury emissions from anthropogenic sources in Maritime Canada for the years 1800-1995. Long-term trends in mercury emissions and the significance of the cumulative burden of mercury released from local sources are discussed. Emissions are calculated using both historical monitoring data and the application of emission factors. The nature of current anthropogenic sources of mercury is quite different than it was several decades ago when many of the existing policies governing mercury pollution were created. Our inventory illustrates that many of the most significant sources in the past such as the chlor-alkali industry, paint containing mercury additives, and pharmaceuticals, have been largely phased out with fossil fuel combustion and waste disposal remaining as the most significant modern sources. Atmospheric emissions in Maritime Canada peaked in 1945 (> 1,750 kg year-1), and again between 1965 and 1970 (> 2,600 kg year-1). Cumulative releases of mercury from anthropogenic sources for the years 1800-1995 were between 115 and 259 t to the atmosphere alone, and 327-448 t when discharges to wastewater and effluents were included. Assuming that only 0.2% (Nriagu, 1994.) of these releases become part of the recycled fraction of current fluxes, we estimate that between 570 and 900 kg Hg year-1 is deposited in Maritime Canada from past anthropogenic sources. Modern sources within Maritime Canada contribute at least 405 kg year-1 to the total annual deposition of 1.71 t over the provinces of New Brunswick, Nova Scotia and Prince Edward Island, leaving approximately 735 kg year-1 from natural sources and long-range contamination. Further study is needed to verify these estimates and clarify the significance of natural and long-range sources of mercury in Maritime Canada.     

Characteristics of PM10, SO2, NO(x) and O3 in ambient air during the dust storm period in Beijing

In this study, the hourly variations of the mass concentrations of PM10, SO2, NO(x) and O3 at three sampling sites were observed in Beijing during dust storm occurrence period in April 2000. The PM2.5 samples were simultaneously collected. By comparing the hourly variations of the pollutant concentrations before, during and after dust storm event and haze pollution episode, the variation characteristics of the mass concentrations of PM10, SO2, NO(x) and O3 during dust storm events were presented. The results show that the mass concentration of PM10 reached 1500 microg m(-3) during dust storm events on April 6 and 25, 2000, which was 5-10 times that of the non-dust weather conditions, and this period of high mass concentration of PM10 lasted for about 14 h, and then the concentration level prior to the dust event was recovered in 6-h time period. Due to the strong wind, the concentrations of SO2, NO(x), NO2 and O3 during dust storm period were maintained at low levels, which was significantly different from those on non-dust storm and haze pollution conditions. A lot of coarse particles as well as a very large amount of fine particles were contained in the atmospheric particulates during dust storm period, and the concentration level of PM2.5 was comparable to that during haze pollution episode. During the dust storm period, the PM2.5 concentration was approximately 230 microg m(-3), accounting for 30% of the total PM10 mass concentration, was four times that of non-dust weather conditions, and the crustal elements constituted about 66.4% of the chemical composition of PM2.5 while sulfate and nitrate contributed much less, which was quite different from the chemical composition of PM2.5 primarily constituted by sulfate, nitrate and organics on haze pollution day.     

Mercury contamination in the vicinity of a chlor-alkali plant and potential risks to local population

A mercury-cell chlor-alkali plant operated in Estarreja (North-western Portugal) for 50 years causing widespread environmental contamination. Although production by this process ceased in 2002, mercury contamination from the plant remains significant. The main objective of this study was to investigate mercury impact on the nearby environment and potential risks to local population. To assess the level of contamination soil samples were collected from agricultural fields in the vicinity of the plant, extending the study by taking samples of the predominant vegetation suitable for animal and human consumption, water samples, and fish species from a nearby coastal lagoon, to gain a preliminary insight into the potential for contamination of the terrestrial and aquatic food web. To determine population exposure to mercury, hair samples were collected from local residents. Total mercury concentration in the 0-15 cm layer of soil was found to be highly variable, ranging between 0.010 and 91 mg kg^− 1, although mercury contamination of soils was found to be restricted to a confined area. Lolium perenne roots contained between 0.0070 and 2.0 mg kg^− 1, and there is evidence that root systems uptake mercury from the soil. Levels of mercury in the aerial parts of plants ranged between 0.018 and 0.98 mg kg^− 1. It appears that plants with higher mercury concentration in soils and roots also display higher mercury concentration in leaves.Total mercury concentration in water samples ranged between 12 and 846 ng L^− 1, all samples presenting concentrations below the maximum level allowable for drinking water defined in the Portuguese law (1.0 μg L^− 1).Mercury levels in fish samples were below the maximum limit defined in the Portuguese law (0.5 mg kg^− 1), ranging from 0.0040 to 0.24 mg kg^− 1. Vegetables collected presented maximum mercury concentration of 0.17 mg kg^− 1. In general, food is not contaminated and should not be responsible for major human exposure to the metal.Mercury determined in human hair samples (0.090-4.2 mg kg^− 1; mean 1.5 mg kg^− 1) can be considered within normal limits, according to WHO guidelines suggesting that it is not affecting the local population. Despite being subject to decades of mercury emissions, nowadays this pollutant is only found in limited small areas and must not constitute a risk for human health, should these areas be restricted and monitored.Considering the present data, it appears that the population from Estarreja is currently not being affected by mercury levels that still remain in the environment.     

Comparative study of mercury accumulation in dolphins (Stenella coeruleoalba) from French Atlantic and Mediterranean coasts

Total mercury concentrations (Hgt) have been determined in liver, kidneys, skeletal muscle, melon, stomach and intestine of 35 specimens of Stenella coeruleoalba stranded on French Atlantic and Mediterranean coasts. Very high mercury levels, with concentrations reaching 80 mg Hgt kg(-1) fresh weight (FW) in muscle and about 1500 mg Hgt kg(-1) FW in liver tissue, were observed. Liver has the highest concentration, followed by muscle and kidney. The lowest concentrations were found in the melon. The levels observed in the Mediterranean specimens are among the highest observed in marine organisms and confirm previous reports of high mercury levels in marine mammals from the Mediterranean. Comparison between Hgt accumulation levels in these two geographic groups of dolphins shows that Mediterranean individuals have much higher concentrations than specimens from the Atlantic. These differences provide additional confirmation for the higher Hgt concentrations observed previously in other pelagic species (tuna, sardine, anchovy, etc.) from the Mediterranean Sea. Taking into consideration the pelagic habitat of the dolphin and the local influence of anthropogenic mercury sources it seems reasonable to assume that the main source of the high mercury concentrations observed in Mediterranean biota is natural mercury deposits located in many regions of the Mediterranean basin.     

Characterization of atmospheric mineral components of PM2.5 in Beijing and Shanghai, China

Weekly PM2.5 samples were collected for one year in Beijing and Shanghai and the crustal elements analyzed to investigate the concentration levels and temporal variations of ambient fine mineral dust. The mass concentrations of Al, Si, Ca, Mg, and Fe exhibited similar significant weekly variations in both Beijing and Shanghai. The annual average PM2.5 concentrations of major crustal elements ranged from 0.27 microg m-3 Mg to 2.48 microg m-3 Si in Beijing, which were 1.40-2.24 times higher than those in Shanghai. Their PM-weighted values were comparable between the two cities. A distinct seasonal pattern was present for these crustal elements with the highest concentrations during the spring in Beijing and during the winter in Shanghai, and the lowest concentrations during the summer in both cities. During the dusty spring of 2000 in Beijing, soil dust was the second most abundant PM2.5 constituent with a contribution as high as 18.6%, over twice that in the winter. The highest fine soil concentration (37.8 microg m-3) and mass percentage (41.6%) occurred in the same week of intensive dust events impacting Beijing. The impact of dust storms complicates the goal of reducing PM2.5 in Beijing. Ca originating from construction activities appears to be a significant PM2.5 contributor as well.     

主体结构施工阶段扬尘监测与规律分析

为了了解建筑工程主体结构阶段的扬尘排放特点,掌握该阶段的扬尘分布规律以加强污染防控,改善施工作业环境。选取北京市两个典型住宅建设项目,以总悬浮颗粒物浓度作为监测指标,使用粉尘采样仪对主体结构施工阶段的各项施工活动进行扬尘浓度实地监测,汇总得到大量扬尘浓度原始数据。通过对比不同施工活动的扬尘污染状况,分析扬尘排放特点及主要分布规律。结果表明:主体结构施工阶段整体扬尘污染并不严重,不同施工活动排放的扬尘浓度存在明显差异,木工棚和道路两侧是扬尘污染严重区域。     

北京市下沉广场地表灰尘重金属污染 特征及健康风险评价

通过采集下沉广场的地表灰尘样品,测定其中重金 属的含量,分析不同元素之间的相关性,探讨环境因素对重 金属含量的影响,采用健康风险评价模型评价相关风险。结 果表明,北京10座下沉广场地表灰尘中Cd、Pb、Cr、Cu、 Zn和Ni的平均含量分别为0.87、45.30、84.88、52.41、 167.47、24.03mg/kg,除Ni外,依次超过了北京土壤背景值 的3.28、0.84、1.85、1.80、1.91倍。灰尘中的Pb、Cu、 Zn含量具有显著正相关关系,人流密度对Cu含量有显著正相 关影响。下沉广场地表灰尘重金属引起的健康风险处于较低水 平。研究结果为下沉广场的设计和养护管理提供了科学依据。     

High levels of antimony in dust from e-waste recycling in southeastern China

Environmental contamination due to uncontrolled e-waste recycling is an emerging global issue. Antimony (Sb) is a toxic element used in semiconductor components and flame retardants for circuit board within electronic equipment. When e-waste is recycled, Sb is released and contaminates the surrounding environment; however, few studies have characterized the extent of this problem. In this study, we investigated Sb and arsenic (As) distributions in indoor dust from 13 e-waste recycling villages in Guiyu, Guangdong Province, southeastern China. Results revealed significantly elevated concentrations of Sb (6.1-232 mg/kg) in dust within all villages, which were 3.9-147 times higher than those from the non e-waste sites, indicating e-waste recycling was an important source of Sb pollution. On the contrary, As concentrations (5.4-17.7 mg/kg) in e-waste dusts were similar to reference values from the control sites. Therefore, dusts emitted from e-waste recycling may be characterized by high Sb/As ratios, which may help identify the contamination due to the e-waste recycling activities.     

Total mercury,methylmercury and selenium in mercury polluted areas in the province Guizhou,China

The province of Guizhou in Southwestern China is currently one of the world's most important mercury production areas. Emissions of mercury from the province to the global atmosphere have been estimated to be approximately 12% of the world total anthropogenic emissions. The main objective of this study was to assess the level of contamination with Hg in two geographical areas of Guizhou province. Mercury pollution in the areas concerned originates from mercury mining and ore processing in the area of Wanshan, while in the area of Quingzhen mercury pollution originates from the chemical industry discharging Hg through wastewaters and emissions to the atmosphere due to coal burning for electricity production. The results of this study confirmed high contamination with Hg in soil, sediments and rice in the Hg mining area in Wanshan. High levels of Hg in soil and rice were also found in the vicinity of the chemical plant in Quingzhen. The concentrations of Hg decreased with distance from the main sources of pollution considerably. The general conclusion is that Hg contamination in Wanshan is geographically more widespread, due to deposition and scavenging of Hg from contaminated air and deposition on land. In Quingzhen Hg contamination of soil is very high close to the chemical plant but the levels reach background concentrations at a distance of several km. Even though the major source of Hg in both areas is inorganic Hg, it was observed that active transformation of inorganic Hg to organic Hg species (MeHg) takes place in water, sediments and soils. The concentration of Hg in rice grains can reach up to 569 microg/kg of total Hg of which 145 microg/kg was in MeHg form. The percentage of Hg as MeHg varied from 5 to 83%. The concentrations of selenium can reach up to 16 mg/kg in soil and up to 1 mg/g in rice. A correlation exists between the concentration of Se in soil and rice, indicating that a portion of Se is bioavailable to plants. No correlation between Hg and Se in rice was found. Exposure of the local population to Hg may occur due to inhalation of Hg present in air (in particular in Hg mining area) and consumption of Hg contaminated food (in particular rice and fish) and water. Comparison of intake through these different routes showed that the values of Hg considerably exceed the USA EPA Reference Concentration (RfC) for chronic Hg exposure (RfC is 0.0004 mg/m(3)) close to the emission sources. Intake of Hg through food consumption, particularly rice and fish, is also an important route of Hg exposure in study area. In general, it can be concluded that the population mostly at risk is located in the vicinity of smelting facilities, mining activities and close to the waste disposal sites in the wider area of Wanshan. In order to assess the real level of contamination in the local population, it is recommended that biomonitoring should be performed, including Hg and MeHg measurements in hair, blood and urine samples.