Environmental geochemistry studies in the area of Idrija mercury mine,Slovenia

Five centuries of mining and processing of mercury ore in the Idrija area have resulted in widespread contamination of different environmental compartments. Environmental impacts on a regional and local scale, caused by atmospheric emissions from the Idrija ore roasting plant, were established in the investigations of mercury spatial distribution in soil and attic dust in 160 km² area. Very high values were determined in the Idrijca River valley, and they decrease exponentially with the distance from Idrija. Mercury concentrations in attic dust are higher than in surrounding soils and the attic dust/soil ratio changes with distance. Measurements of mercury in the air confirmed widespread dispersion of mercury and showed highly elevated mercury concentrations around roasting plant and mine ventilation shaft. Beside, systematic monitoring of mercury contents in the stream sediments has demonstrated that huge amounts of mercury are stored in areas where ancient overbank sediments were deposited, and there was no decrease in mercury concentration in active sediments during the last 15 years. Recently, interesting and extremely polluted locations of historical small-scale roasting sites in the Idrija surroundings were discovered. Ongoing geochemical study aims to determine the extreme pollution and significance of these sites for wider contamination of soils and aquatic systems. Presented studies have shown that Hg mining in Idrija caused intense pollution of local and regional environment including the aquatic systems in the Gulf of Trieste, which is seen as the final sink of a major part of the Hg stored in soils and river sediments in the Idrija area.     

Environmental geochemistry studies in the area of Idrija mercury mine,Slovenia

Five centuries of mining and processing of mercury ore in the Idrija area have resulted in widespread contamination of different environmental compartments. Environmental impacts on a regional and local scale, caused by atmospheric emissions from the Idrija ore roasting plant, were established in the investigations of mercury spatial distribution in soil and attic dust in 160 km² area. Very high values were determined in the Idrijca River valley, and they decrease exponentially with the distance from Idrija. Mercury concentrations in attic dust are higher than in surrounding soils and the attic dust/soil ratio changes with distance. Measurements of mercury in the air confirmed widespread dispersion of mercury and showed highly elevated mercury concentrations around roasting plant and mine ventilation shaft. Beside, systematic monitoring of mercury contents in the stream sediments has demonstrated that huge amounts of mercury are stored in areas where ancient overbank sediments were deposited, and there was no decrease in mercury concentration in active sediments during the last 15 years. Recently, interesting and extremely polluted locations of historical small-scale roasting sites in the Idrija surroundings were discovered. Ongoing geochemical study aims to determine the extreme pollution and significance of these sites for wider contamination of soils and aquatic systems. Presented studies have shown that Hg mining in Idrija caused intense pollution of local and regional environment including the aquatic systems in the Gulf of Trieste, which is seen as the final sink of a major part of the Hg stored in soils and river sediments in the Idrija area.

     

Urban sediment contamination in a former Hg mining district,Idrija, Slovenia

Road sediments from gully pots of the drainage system and stream sediments from local streams were investigated for the first time in the urban area of Idrija town, the central part of the second largest and strongly contaminated Hg mining district in the world. Hg concentrations in road sediments were lower than in stream sediments. They ranged from 16 to 110 mg/kg (Md = 29 mg/kg) for <0.125 mm particles and from 7 to 125 mg/kg (Md = 35 mg/kg) for <0.04 mm particles, while Hg concentrations in stream sediments ranged from 10 to 610 mg/kg (Md = 95 mg/kg) for <0.125 particles and from 10 to 440 mg/kg (Md = 105 mg/kg) for <0.04 mm particles. High Hg loadings in stream sediments were successfully linked with identified mercury sources (rocks containing mercury ore, areas of former ore roasting sites, ore residue dumps), because they are located in the drainage areas of streams, from which the sediments were collected. Links between Hg loadings in road sediments and identified mercury sources were not recognized. Solid phases of Hg were determined by thermo-desorption technique and are similar for both types of sediments. Results show the occurrence of three different forms: elemental mercury, mercury bound to matrix components and cinnabar. Approximately 50 % of Hg in samples consist of non-cinnabar fractions. This is important, since they are potentially bioavailable. An interesting new discovery according to previous research of environmental media from Idrija area by solid-phase Hg thermo-desorption technique is that elemental mercury was determined in almost all investigated sediments in minor amounts (Md = 3 %).     

Geochemical investigation of potentially harmful elements in household dust from a mercury-contaminated site,the town of Idrija (Slovenia)

A comprehensive geochemical investigation of potentially harmful elements (PHEs) in household dust from the town of Idrija (Slovenia), once a world-famous Hg mining town that is now seriously polluted, was performed for the first time. After aqua regia digestion, the content of mercury (Hg), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), molybdenum (Mo), nickel (Ni), lead (Pb) and zinc (Zn) was measured. PHE-bearing particles were recognised and observed by scanning electron microscopy and energy-dispersive spectrometry before and after exposure to simulated stomach acid (SSA). Mercury binding forms were identified by Hg thermal desorption technique and gastric bioaccessible Hg was estimated after SSA extraction by ICP-MS. With regard to rural and urban background values for Slovenia, high Hg content (6–120 mg/kg) and slightly elevated As content (1–13 mg/kg) were found. Mercury pollution is a result of past mining and ore processing activities. Arsenic content is potentially associated with As enrichment in local soils. Four Hg binding forms were identified: all samples contained Hg bound to the dust matrix, 14 samples contained cinnabar, two samples contained metallic Hg (Hg⁰), and one sample assumingly contained mercury oxide. After exposure to SSA, Hg-bearing phases showed no signs of dissolution, while other PHE-bearing phases were significantly morphologically and/or chemically altered. Estimated gastric Hg bioaccessibility was low (<0.006–0.09 %), which is in accordance with identified Hg binding forms and high organic carbon content (15.9–31.5 %) in the dust samples.     

Seasonal distribution and speciation of mercury in a gold mining area,north-west province,South Africa

The seasonal speciation of mercury (Hg) was determined in water, soil, and sediments from watersheds located in the North-West province of South Africa. The study area is known to have a long history of mining activities which also include the recovery of gold from old tailings. Both inorganic (IHg) and methyl mercury (MHg) were detected at high concentrations (up to 8480 μg IHg kg^?1 and 13 μg MHg kg^?1) in surface sediments during dry season. A considerable remobilization of Hg from bottom sediments was observed in water from dry to wet season as well as the migration of Hg away from pollution sources due to seasonal influences. Hg in sediments mostly has been speciated as Hg⁰. Enhancement of Hg methylation occurred mainly in deeper sediments at regions corresponding to the lowest redox potential, higher pH, and enrichment of IHg. Hg values in borehole waters were very high (up to 3310 ng L^?1) suggesting a serious contamination of the site groundwater which needs to be addressed urgently in order to minimize further impact that affects the Vaal River and other water systems located nearby.     

Trace elements distributions at Datoko-Shega artisanal mining site,northern Ghana

Environmental geochemistry classifies elements into essential, non-essential and toxic elements in relationship to human health. To assess the environmental impact of mining at Datoko-Shega area, the distributions and concentrations of trace elements in stream sediments and soil samples were carried out. X-ray fluorescence analytical technique was used to measure the major and trace element concentrations in sediments and modified fire assay absorption spectrometry in soils. The results showed general depletion of major elements except titanium oxide (TiO₂) compared to the average crustal concentrations. The retention of TiO₂ at the near surface environment probably was due to the intense tropical weathering accompanied by the removal of fine sediments and soil fractions during the harmattan season by the dry north-east trade winds and sheet wash deposits formed after flash floods. The results also showed extreme contamination of selenium (Se), cadmium (Cd) and mercury (Hg), plus strong contaminations of arsenic (As) and chromium (Cr) in addition to moderate contamination of lead (Pb) in the trace element samples relative to crustal averages in the upper continental crust. However Hg, Pb and Cd concentrations tend to be high around the artisanal workings. It was recognised from the analysis of the results that the artisanal mining activity harnessed and introduces some potentially toxic elements such as Hg, Cd and Pb mostly in the artisan mine sites. But the interpretation of the trace element data thus invalidates the elevation of As concentrations to be from the mine operations. It consequently noticed As values in the mine-impacted areas to be similar or sometimes lower than As values in areas outside the mine sites from the stream sediment results.

     

湘南4个矿区稻田As污染状况的初步调查

通过实地调查以及土壤和水稻样品分析,研究了湘南郴州柿竹园铅锌矿、郴州界牌岭锡多金属矿、衡阳水口山有色金属矿、衡阳龙王山金矿4个矿区稻田的As污染状况.结果表明:4个矿区的稻田土壤和水稻植株均已受到严重的As污染.矿区稻田土壤As含量范围为30.0～225.7mg·kg-1,超过国家土壤环境质量3级标准;水稻根系、秸秆、谷壳、糙米As含量范围分别为115.6～588.2、4.19～20.88、1.388～5.374、0.214～0.892mg·kg-1,除部分糙米样品外,均超过我国食品中As限量卫生标准.矿区稻田土壤同时受到As和重金属的复合污染,综合污染指数(P)范围为0.76～13.12.矿区稻田的As污染主要由矿产的开采和冶炼造成,其中,水口山有色金属矿区和龙王山金矿区As污染以及As和重金属复合污染最为严重,柿竹园铅锌矿区污染面积较大,界牌岭锡多金属矿区由于发生过地质灾害改变了地表面貌,污染情况更为复杂.     

福建省菜园土壤重金属的含量及其污染评价

采集了福建省26个县市158份菜园表层土壤样品,测定了土壤样品中重金属含量,采用单项及综合污染指数法对土壤重金属污染进行评价分析,并通过元素相关性分析和聚类分析,研究了菜园土壤重金属元素的赋存特征与区域分布.结果表明,福建省菜园土壤存在着不同程度的重金属污染,主要污染元素为Pb,Hg和Cd;元素相关性分析与聚类分析的结果表明:Cu,Zn,Ni和As具有伴随污染的特点,其污染源主要来自土壤母质和大量施用的农药和化肥;Cd,Pb和Hg在土壤中各聚成一类,说明它们在菜园土壤具有较独特的污染源,特别是Cd和Hg,其污染特征明显.而Pb和Cd虽有各自的污染源,但其污染具有一定的相关性.     

Atmospheric mercury emissions from polluted gold mining areas (Venezuela)

Soil, waste rock and mud from mercury-gold amalgamation mining areas of El Callao (Venezuela) are highly enriched in Hg (0.5–500 μg g⁻¹) relative to natural background concentrations (<0.1 μg g⁻¹). Mercury fluxes to the atmosphere from twelve polluted sites of this area were measured in situ (6 a.m. to 8 p.m.) using a Plexiglas flux chamber connected to a portable mercury analyzer (model RA-915+; Lumex, St. Petersburg, Russia). Mercury fluxes ranged between 0.65 and 420.1 μg m⁻² h⁻¹, and the average flux range during the diurnal hours␣was 9.1–239.2 μg m⁻² h⁻¹. These flux values are five orders of magnitude higher than both reported world background Hg fluxes (1–69 ng m⁻² h⁻¹) and the regional values, which are in the range 2–10 ng m⁻² h⁻¹. The flux results obtained in this study are, however, similar to those measured at Hg polluted sites such as chloro-alkali plants or polymetallic ore mining districts (>100,000 ng m⁻² h⁻¹). The results from this study also show that Hg emissions from the soil are influenced by solar radiation, soil temperature and soil Hg concentration. Our data suggest that solar radiation may be the dominant factor affecting Hg° emission since the major species of mercury in polluted soil is Hg° (85–97% of total Hg). The simple release of Hg° vapor is probably the dominant process occurring with incident light in the field. The apparent activation energy for mercury emission indicates that the volatilization of mercury mainly occurred as a result of the vaporization of elemental mercury in soil. The degree of Hg emission differed significantly among the soil sites studied, which may be due to variations in soil texture, organic matter content and soil compaction.     

Mercury contamination in selected foodstuffs and potential health risk assessment along the artisanal gold mining,Gilgit-Baltistan,Pakistan

This study investigates the mercury (Hg) contaminations in soil and foodstuffs along the artisanal gold mining areas, Gilgit-Baltistan Province, Pakistan. For this purpose, soils were analyzed for Hg concentrations and evaluated for the enrichment/contamination using enrichment factor or contamination factors (CF). The CF values ranged from 18.9 to 153 showed multifold higher levels of Hg contamination as compared to background or reference site. Foodstuffs including vegetables, seeds or grains and fish muscles showed Hg accumulation. Results revealed that Hg concentrations in foodstuffs were higher than the critical human health value set by European Union. The Hg in foodstuffs was consumed and, therefore, evaluated for the risk assessment indices using the daily intake (DI) and health risk index (HRI) for the exposed human population both children and adults. Results of this study revealed that cumulative HRI values through foodstuffs consumption were <1 (within safe limit), but if the current practices continued, then the Hg contamination could pose potential threat to exposed population in near future.     

广州市蔬菜地土壤-蔬菜中重金属Hg的含量及变化趋势

测定了95份土壤样品、94份水样以及292份蔬菜样品中汞的含量,探讨了广州市蔬菜地土壤-蔬菜中重金属Hg污染状况.发现蔬菜中的Hg含量与土壤中的Hg含量较为密切.广州市土壤、蔬菜中Hg的含量水平均比过去大幅度降低.蔬菜中Hg含量与其它城市比较,污染情况较轻,处于其它城市的中低水平.     

Metal contamination of active stream sediments in upper Weardale,northern Pennine Orefield,UK

In the Upper Weardale area the headwaters of the River Wear bisect the Northern Pennine Orefield, where Pb-Zn-F-Ba vein-type mineralisation has been exploited since the Roman Conquest. The area contains evidence of open pit, underground and hydraulic mining of base metal ores, associated mineral processing and smelting, exploitation of ironstones during the industrial revolution, recent extraction of fluorite and active quarrying. The aim of this study was to determine the extent of modern sediment contamination arising from these past activities. Samples of active stream sediments were collected from all major drainage channels at 1 km intervals. The sediments were analysed for Pb, Zn, Ba, Mn, Fe, Co, Ni, Cu, Cr, As, Sb, Ag and compared to data from earlier regional geochemical surveys of low order drainage samples using ArcView software. The significance of contamination levels was assessed using the Ontario aquatic sediment quality guidelines. Our results indicate widespread contamination of some major drainages by Pb, Mn, Zn and As at concentration levels anticipated to significantly affect use of the sediments by benthic organisms. Furthermore, Pb contamination shows persistence in stream sediments downstream towards agricultural areas of the floodplain and drinking water abstraction points, above which interaction with colliery mine water discharges may occur.     

北京市表层浮土和水体底泥中汞的赋存形态及其相互关系

应用分级萃取法测定了12个北京市表层浮士和3个水体底泥中汞的赋存形态,并应用多元统计分析对其相互关系进行了研究.北京市表层浮土中汞的含量分布变异较大,但其趋势为:残渣态>强有机结合态>水溶态>其它形态.各形态汞含量主要取决于上壤和底泥中汞含量的大小,其次才是环境因素.强有机结合态和残渣态是主要的赋存形态,对汞在土壤和底泥中的固定起着重要的作用.较易移动的水溶态、FA结合态和交换态对汞在环境中的迁移转化也有一定的影响.盐酸提取态汞主要包括水溶态、交换态、FA结合态和碳酸盐结合态.     

典型菜地土壤汞在小白菜和胡萝卜可食部位的富集规律

对广东省蔬菜种植面积较大的10个城市典型菜地土壤和蔬菜（小白菜和胡萝卜）对应采样,分析217个蔬菜可食部位中重金属汞（Hg）质量分数及对应土壤中Hg全量和有效态质量分数,研究大田条件下小白菜和胡萝卜可食部位富集Hg的规律。结果表明,广东省菜地土壤存在一定的Hg污染,约20％的土壤超过国家土壤环境质量标准（GBl5618－1995）中二级标准值,但小白菜和胡萝卜中Hg质量分数较低,均值分别为0．0012和0．0013mg·kg-1,仅2个小白菜样品Hg质量分数超过国家食品卫生标准《食品中污染物限量》（GB2762-2005）中的限值0．01mg·kg-1。TGA提取的土壤有效态Hg质量分数与土壤Hg全量显著正相关,TGA提取Hg量仅占土壤总Hg质量分数的3％-4％。小白菜和胡萝卜对Hg的富集系数分别为0．90％和0．94％,表明土壤中绝大部分的Hg不易转化迁移、为蔬菜吸收。小白菜和胡萝卜可食部位Hg质量分数与土壤中Hg全量和有效态质量分数均存在显著的线性关系,其中蔬菜与土壤Hg有效态质量分数的关系优于其与土壤Hg全量的关系。依据国家食品卫生标准,通过拟合回归方程计算出的保障小白菜和胡萝b质量安全的菜地土壤Hg有效态质量分数临界值分别为O．038和0．063mg·kg-1。计算出的土壤Hg全量临界值远大于我国现行土壤环境质量标准的二级标准值,表明该标准值对于保障广东省小白菜和胡萝b质量安全来说可能过于严格。     

Distribution,fractionation and risk assessment of mercury in surficial sediments of Nansi Lake,China

Nansi Lake is composed of four sub-lakes from north to south: Nanyang Lake, Dushan Lake, Zhaoyang Lake and Weishan Lake. An environmental pollution investigation was carried out to determine the fractionation, and pollution assessments of mercury (Hg) in surficial sediments from Nansi Lake. Results showed that the mean concentration of Hg was 3.1 times higher than its background value (0.015 mg kg^?1), and the high concentration of Hg which even reached up to five times than the background value in the part of Dushan Lake and Weishan Lake, which indicated that there are obvious spatial differences. The content of Hg was positively correlated with that of total organic carbon, and negatively correlated with that of pH and SiO₂ in surface sediments. An improved Tessier sequential extraction procedure was used to study the fractions of Hg in sediments. The results indicated that Hg existed primarily in the fraction of residual, which accounts for 58.4% of total mercury (THg), and the percentage of extractable Hg was only 1.93% of total mercury. High concentrations of mercury of non-residual phase were found in part lake area from the Nanyang Lake and the Weishan Lake, which indicating a higher potential ecological risk relative to the other lake areas. Based on the values of enrichment factor and geo-accumulation index, most part of Dushan Lake and Nanyang Lake and Weishan Lake were in a moderate pollution. And based on the fractionation of mercury, risk assessment code of Hg exhibited low risks to the environment in Nansi Lake.     

A 1955�C2004 record of Hg contamination in Dianshan Lake sediments, Shanghai

Measuring Hg levels of water sediments is one of the primary routes to assess the trend of the contamination. Little work has been carried out in the Yangtze Delta to track the trend of mercury contamination caused by Shanghai, which is one of the fastest growing economies in the world today. The mercury concentration in the sedimentary cores from Dianshan Lake, Shanghai is studied here. Results show that mercury transported to Dianshan Lake from emissions of coal combustion and non-coal sources in the Yangtze Delta was greater after 1979. We found also that before 1979 mercury levels changed less with time than after 1979. Before 1967 Hg levels were more variable than in the 1970s. Moreover, the mercury dissolved in river water and bound to particles of water that flow past downtown Shanghai is different from that observed in Dianshan Lake, which is located in upper Shanghai. This indicates that atmospheric Hg deposition is probably the main source of mercury in Dianshan Lake. These results are important for the establishment of environmental protections and pollution treatment proposals for mercury in similar areas of the world, as well as in Shanghai.     

Mercury concentrations in the surface sediments of the intertidal area along the west coast of Peninsular Malaysia

Total mercury (Hg) levels in the intertidal surface sediments along the west coast of Peninsular Malaysia were analysed by using heat vaporization method. Total Hg levels in these sediments ranged from 3.00 to 201?µg?kg^?1 dry weight with a mean concentration of 60.0?µg?kg^?1 dry weight. More than 90% of the samples studied have the total Hg concentrations less than 150?µg?kg^?1 dry weight. Compare with the regional data and sediment quality guidelines, the Hg contamination in the intertidal area along the west coast of Peninsular Malaysia was not serious, except for a few sites that might have received anthropogenic Hg in the samples collected between 1999 and 2000. It is suggested that a similar study of heavy metals in the sediments of the west coast of Peninsular Malaysia be conducted regularly.     

Heavy metals in soils and crops in Southeast Asia

In a reconnaisance soil geochemical and plant survey undertaken to study the heavy metal uptake by major food crops in Malaysia, 241 soils were analysed for cation exchange capacity (CEC), organic carbon (C), pH, electrical conductivity (EC) and available phosphorus (P) using appropriate procedures. These soils were also analysed for arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) using aqua regia digestion, together with 180 plant samples using nitric acid digestion. Regression analysis between the edible plant part and aqua regia soluble soil As, Cd, Cr, Cu, Hg, Ni, Pb and Zn concentrations sampled throughout Peninsular Malaysia, indicated a positive relationship for Pb in all the plants sampled in the survey (R2 = 0.195, p < 0.001), for Ni in corn (R2 = 0.649, p < 0.005), for Cu in chili (R2 = 0.344, p < 0.010) and for Zn in chili (R2 = 0.501, p < 0.001). Principal component analysis of the soil data suggested that concentrations of Co, Ni, Pb and Zn were strongly correlated with concentrations of Al and Fe, which is suggestive of evidence of background variations due to changes in soil mineralogy. Thus the evidence for widespread contamination of soils by these elements through agricultural activities is not strong. Chromium was correlated with soil pH and EC, Na, S, and Ca while Hg was not correlated with any of these components, suggesting diffuse pollution by aerial deposition. However As, Cd, Cu were strongly associated with organic matter and available and aqua regia soluble soil P, which we attribute to inputs in agricultural fertilisers and soil organic amendments (e.g. manures, composts).     

Mercury distribution in the sediments of Ambarlı Port Area,Sea of Marmara (Turkey)

The purpose of this study is to investigate historical and current mercury (Hg) contamination in the surface and core sediments of the Ambarl? Port area. Textural parameters, total organic carbon (TOC), ²¹⁰Pb and total Hg (THg) contents were measured. Mercury contamination of the sediments was assessed on the basis of the enrichment factor (EF), anthropogenic factor (AF), index of geoaccumulation (Igeo) and corresponding sediment quality guidelines. Most surface sediment samples were also non-toxic with mercury concentrations below the effects range-low (ERL) value, but mercury levels at five stations were between ERL and effects range-median (ERM) values, where occasional adverse effects concerning risk analysis are expected. The EF and Igeo analysis showed that there was no significant mercury enrichment and contamination in the core sediment before the 1650s, but values increased from then onwards to 2009 (being especially accelerated in line with port activities from 1989), disclosing a serious ecotoxicological risk to sediment-inhabited marine organisms.     

中国城市土壤重金属污染研究现状及对策

中国城市土壤重金属污染的主要来源是工业“三废”排放，金属采矿和冶炼，家庭燃煤，生活垃圾，汽车尾气排放。重金属在城市土壤中的分布规律表现为城市土壤重金属含量高于郊区，人类活动密集区和交通拥挤区重金属含量较高；人类活动的干扰导致土壤剖面重金属污染特征不明显。应采取预防与治理相结合的措施综合控制土壤重金属污染，并加紧制定我国的城市土壤健康评价标准。