Distribution Of Mercury In Soils Research Articles

Distribution of Mercury in Soil, Water, and Vegetable Fern in a Former Gold Mining Area – Evidence from Nagan Raya Regency, Aceh Province, Indonesia

Distribution of Mercury in Soil, Water, and Vegetable Fern in a Former Gold Mining Area – Evidence from Nagan Raya Regency, Aceh Province, Indonesia

Total mercury content in soils and lake sediments of Vilkitsky Island (Kara Sea)

Mercury threatens Arctic ecosystems due to its well known deleterious effects. The development of energy resources in the Russian Arctic is currently being planned, which will inevitably be accompanied by emissions of heavy metals into the environment, but little is known about the distribution of mercury in soils of the permafrost regions. Total mercury (THg) concentrations were investigated in soils and lake sediments of Vilkitsky Island located in remote area of the Arctic. The concentration of mercury in soils varied from 1 to 36,6 ng g−1, in lake sediments – from 2.0 to 5.8 ng g−1. In sandy soils of the iseland the concentration of THg was minimal and was usually not higher than10 ng g−1, whereas in loamy soils it was 3.5 times higher. Correlation analysis has shown that THg concentration depended primarily on particle size distribution, in a lesser degree – on total carbon and total nitrogen concentrations. The soils of Viltisky Island have one of the lowest mercury concentration in comparison to soils of other Arctic territories, because of the predominance of sandy marine sediments and low soil organic matter content. Under influence of human activities, THg content has increased three-fold on average. The highest concentrations were observed in soils of an abandoned polar station. Calculation of CF and Igeo coefficients demonstrated the high level of mercury pollution on local sites. The maximum content of mercury (25.7-36.7 ng g-1) was observed in coastal sediments. It is assumed that the increased mercury content is a consequence of translocation. Thus, the coastal areas of the Arctic islands are at the greatest danger of pollution.

МОНИТОРИНГ ТЕХНОГЕННОЙ ТРАНСФОРМАЦИИ ГОРОДСКИХ ПОЧВ (НА ПРИМЕРЕ г. ТОМСКА)

The problem of technogenic mercury pollution in urban areas and the technogenic transformation of soil in urban areas is considered. Quantitative estimates of the distribution of mercury in soils in the territory of the city of Tomsk were obtained, which indicate concentrations do not exceed the MPC, but are characterized by enrichment in mercury. In Tomsk, the formation of mercury dispersion halos is associated with the activities of the main city-forming enterprises, as well as vehicles. In addition, the relief of the city and the prevailing direction of the winds form hotbeds of increased content of elements. In urban soils, mercury is present mainly in the insoluble fraction. However, in the composition of the insoluble fraction, most of element No. 80 is in the form of organocomplexes, which indicates highly toxic and bioavailable pollutant compounds in soils in the territory of the city of Tomsk. Geochemical associations of mercury with other chemical elements belong to the environmental factor of environmental impact. It should be noted that the list of elements with high average contents for 25 years of research has not changed. And the concentration of elements decreased significantly, which indicates a decrease in the coefficient of their technophilicity. At the same time, the general technical properties of soils, as well as their material and mineralogical composition, indicate technogenic transformation in comparison with background territories.

The use of a geostatistical model supported by multivariate analysis to assess the spatial distribution of mercury in soils from historical mining areas: Karcz\xf3wka Mt., Miedzianka Mt., and Rudki (south-central Poland)

For the purpose of this study, 181 soil samples were collected from three post-mining areas (Miedzianka Mt. (62), Karczówka Mt. (61), and Rudki (58)) in the Holy Cross Mountains, south-central Poland. Collected samples were dried, disaggregated, and digested in a closed microwave system. All solutions were analyzed for Hg concentrations with cold vapor-atomic absorption spectroscopy (CV-AAS) technique using a continuous flow vapor accessory. The average Hg concentrations and the upper limits of geochemical background (UBG) were as follows: Miedzianka Mt. Hg 0.501 mg kg−1, UBG 0.312 mg kg−1; Karczówka Mt. Hg 0.150 mg kg−1, UBG 0.180 mg kg−1; Rudki area Hg 0.216 mg kg−1, UBG 0.193 mg kg−1. The use of a spatial distribution map of mercury concentrations integrated with computed geochemical factors and results of cluster analysis showed a direct relationship between mercury contents and mining activity conducted in these areas. Only in the case of Miedzianka Mt., this relationship was visible and probably resulted from the presence of tennantite (Cu,Fe)12As4S13 in soil samples, which was also confirmed with the factor analysis. Higher Hg concentrations in soil samples from Karczówka Mt. and Rudki resulted from the presence of clay and other secondary minerals that increase the mercury adsorption from atmospheric deposition. Fossil fuel and biomass combustion was classified as the main anthropogenic source of the metal, but the neighborhood of a cement factory may be taken under consideration. Our results showed that the use of integrated geostatistical models allows for better data visualization and interpretation.

DISTRIBUTION OF MERCURY IN NATURAL AND URBAN ENVIRONMENTS OF KARELIA, NORTHWEST RUSSIA

Purpose. We studied accumulation of mercury in the main natural and urban environments of Karelia, Northwest Russia, and assessed potential sources of mercury in a human body. Methods. A total of 200 samples of soil, vegetation, water, surface water, sediments and fish were collected. An analysis of samples was carried out by cold steam atomic absorption method. Diagrams of mercury distribution in soil, birch leaves and lichens were created. Data on fish consumption by the population of Petrozavodsk and Medvezhyegorsk are studied. The concentration of mercury in fish muscles most consumed in Petrozavodsk and Medvezhyegorsk was estimated. Results. Levels of mercury accumulation in soil and vegetation in the studied settings do not exceed the standards adopted in Russia. The same was observed for mercury concentration in water and sediments. Calculation of mercury intake showed that there is a 3-fold difference in the annual intake of mercury in the human body due to differences in the structure of fish consumption in these cities. Summary. External factors do not lead to higher concentrations of mercury in the main natural and urban environments of Karelia. High concentration of mercury in biological samples of pregnant women in the Medvezhyegorsk district is due to the peculiarities of the diet of the local population - the predominance in the diet of freshwater fish (pike, perch, pike perch) caught directly in the Onega lake.

Distribution pattern of mercury in the Slovenian soil: Geochemical mapping based on multiple geochemical datasets

A regional geochemical survey was conducted, covering the entire territory of Slovenia. Medium-density soil sampling was performed in a 5×5km grid, mercury concentrations were analysed and a map of mercury spatial distribution was constructed. The determined mercury concentrations revealed an important difference between the western and the eastern parts of the country. A huge anomaly in the western part is the consequence of environmental contamination due to the 500-year history of mining and ore processing in the Idrija mercury mine and partly due to Hg containing rocks on outcrops. Slightly elevated Hg concentrations revealed in the Ljubljana-Kranj and Celje basins indicate urban pollution due to industry, traffic and the use of mercury-containing products. It was established that, besides anthropogenic impacts, lithological and climatic characteristics that determine the type of soil also influence the distribution of mercury in soils. The data were compared to a previously conducted low-density geochemical survey (sampling grid 25×25km, n=54) and to the regional geochemical data set supplemented by local high-density sampling data (irregular grid, n=2835). Comparing high-, medium- and low-sample density surveys, it was shown that higher sampling density allows the identification and characterization of anthropogenic influences on a local scale, while medium- and low-density sampling reveal general trends in the mercury spatial distribution, but are not appropriate for identifying local contamination in industrial regions and urban areas.

Speciation and distribution of mercury in soils around gold mines located upstream of Miyun Reservoir, Beijing, China

Long-term mining and smelting activities have contaminated gold mine soils and sediments close to Miyun Reservoir. Several studies have reported concentrations of mercury (Hg) in the Miyun Reservoir area, but this paper presents the first comprehensive study of the distribution and speciation of Hg in this area. The gold mines upstream of the Miyun Reservoir were selected for study. Our results indicate that the total Hg contents in soils (average of 9.57mg·kg−1) were higher in the study area than background values for Beijing surface soils. Samples suggest that Hg distributed as from a point source around the tailings, suggesting that tailings are the major sink for anthropogenic Hg in the study area. Total Hg had a negative correlation with cation exchange capacity, while pH and total organic carbon showed little correlation with total Hg. Hg in soils existed mainly in residual form, with bioavailable Hg accounting for only 0.30% of total Hg. High pH conditions were conductive to the formation of Fe–Mn oxide-bound Hg in mine soils. The Müller geoaccumulation index used to assess pollution indicates that Hg had very serious pollution levels within the study area, requiring urgent management to prevent residual Hg becoming exchangeable through humic acid conversion and entering the watershed.

大伙房水库土壤汞动态与污染特征研究

为了解大伙房水库汞污染现状和环境风险，选择10个采样点，采集了30个土壤样品，20个水体样品，30个空气样品，分析不同区域土壤、水体和大气中的总汞含量及分布，并采用地累积指数法和潜在生态风险指数法对比探讨了土壤总汞污染现状和环境风险，分析其生物可利用性及其潜在风险，探究大气汞与土壤汞富集的关系。结果表明，大伙房水库土壤中的汞平均含量分别为27.76 μg/kg，变异系数为69.32，最大值为82.47 μg/kg，最小值为12.49 μg/kg；大伙房水库采集水中的汞平均含量分别为19.87 μg/kg，变异系数为71.35，最大值为53.82 μg/kg，最小值为2.92 μg/kg。向大气释放汞的年排放通量17.80~62.47 μg/m2/h，平均37.76 μg/m2/h。土壤汞含量与大气汞浓度的相关系数为0.81** (P < 0.01)，相关显著，土壤汞富集对大气汞污染的贡献较大。从汞的空间分布表明，社河流域汞金属污染较低，浑河苏子河流域沉积物汞金属含量较高，水中汞含量较低。地累积指数的土壤汞污染评价和潜在生态危害指数的土壤汞生态风险评价，两种评价结果表明大伙房水库污染水平和生态风险都较低，大气汞污染对土壤汞富集的贡献较大。 To explore the pollution situation and the environmental risk of mercury in Dahuofang reservoir, we choose 10 sampling points, collected 30 soil samples, 20 water samples and 30 air samples to analyze the contents and distribution of mercury in soil, water and air in different areas. We discuss the pollution status and environmental risks of mercury in soil, analyze the biological availability and potential risks and explore the relationship between the atmospheric mercury and the soil mercury enrichment by the geoaccumulation index method and potential ecological risk index method. The results indicated that the average content of mercury in the soil of Dahuofang reser-voir were 27.76 μg/kg, the variation coefficient was 69.32, The maximum was 82.47 μg/kg, the minimum was 12.49 μg/kg; The average content of mercury in the collected water of Dahuofang reservoir were 19.87 μg/kg, The variation coefficient was 71.35, the maximum was 53.82 μg/kg, the minimum was 2.92 μg/kg. The released mercury flux into the atmosphere was 17.80 - 62.47 μg/m2/h, the average was 37.76 μg/m2/h. The correlation coefficient between mercury content in soil and the mercury concentration in atmospheric was 0.81** (P < 0.01), they were significantly correlated. The soil mercury enrichment contributed greatly to atmospheric mercury pollution. According to the spatial distribution of mercury, it indicated that the river was slightly polluted. The mercury content in sediment of Hun River and Suzi River was higher, and the content of mer-cury in water was lower. The evaluation of soil mercury pollution by geoaccumulation index method and the soil mercury ecological risk assessment by potential ecological risk index method. The results showed that the pollution level and the ecological risk of Dahuofang reservoir were low, atmospheric mercury pollution contributed great to soil mercury enrichment.

Determination, speciation and distribution of mercury in soil in the surroundings of a former chlor-alkali plant: assessment of sequential extraction procedure and analytical technique

BackgroundThe paper presents the evaluation of soil contamination with total, water-available, mobile, semi-mobile and non-mobile Hg fractions in the surroundings of a former chlor-alkali plant in connection with several chemical soil characteristics. Principal Component Analysis and Cluster Analysis were used to evaluate the chemical composition variability of soil and factors influencing the fate of Hg in such areas. The sequential extraction EPA 3200-Method and the determination technique based on capacitively coupled microplasma optical emission spectrometry were checked.ResultsA case study was conducted in the Turda town, Romania. The results revealed a high contamination with Hg in the area of the former chlor-alkali plant and waste landfills, where soils were categorized as hazardous waste. The weight of the Hg fractions decreased in the order semi-mobile > non-mobile > mobile > water leachable. Principal Component Analysis revealed 7 factors describing chemical composition variability of soil, of which 3 attributed to Hg species. Total Hg, semi-mobile, non-mobile and mobile fractions were observed to have a strong influence, while the water leachable fraction a weak influence. The two-dimensional plot of PCs highlighted 3 groups of sites according to the Hg contamination factor. The statistical approach has shown that the Hg fate in soil is dependent on pH, content of organic matter, Ca, Fe, Mn, Cu and SO42- rather than natural components, such as aluminosilicates. Cluster analysis of soil characteristics revealed 3 clusters, one of which including Hg species. Soil contamination with Cu as sulfate and Zn as nitrate was also observed.ConclusionsThe approach based on speciation and statistical interpretation of data developed in this study could be useful in the investigation of other chlor-alkali contaminated areas. According to the Bland and Altman test the 3-step sequential extraction scheme is suitable for Hg speciation in soil, while the used determination method of Hg is appropriate.

The MERSADE (European Union) project: Testing procedures and environmental impact for the safe storage of liquid mercury in the Almadén district, Spain

The MERSADE Project (LIFE — European Union) tested the Las Cuevas decommissioned mining complex (Almadén mercury district, Spain) as a potential site for the installation of a future European prototype safe deposit of surplus mercury from industrial activities. We here present the results of a baseline study on the distribution of mercury in soils and air in the Las Cuevas complex and surrounding areas, and show the results of a plume contamination model using the ISC-AERMOD software. Despite restoration works carried out in 2004, the Las Cuevas complex can still be regarded as hotspot of mercury contamination, with large anomalies above 800 μg g − 1 Hg (soils) and 300 ng Hg m − 3 (air). In the case of soils, high, and persistent concentrations above 26 μg g − 1 Hg extend well beyond the complex perimeter for more than 2 km. These concentrations are about three orders of magnitude above world baselines. The same applies to mercury in air, with high concentrations above 300 ng Hg m − 3 inside the perimeter, which nonetheless fade away in a few hundred meters. Air contamination modelling (Hg gas) predicts formation of a NW–SE oriented narrow plume extending for a few hundred meters from the complex perimeter. The geographic isolation of Las Cuevas and its mining past make the complex an ideal site for mercury stocking. The only potential environmental hazards are the raising of livestock only a few hundred meters away from the complex and flash floods.

Mercury mobilization by chemical and microbial iron oxide reduction in soils of French Guyana

Iron oxy(hydr)oxides (oxides) are important mercury sinks in tropical oxisols and the geochemistry of these two elements are thus closely entwined. We hypothesized that bacterial Fe-oxide reduction in anoxic conditions could be a significant mechanism for mobilizing associated Hg. Iron oxide and mercury solubilisation in presence of two chemical reducers (ascorbate and dithionite, dissolving amorphous and amorphous plus well crystallized Fe-oxides, respectively) was compared to their solubilisation in presence of autochthonous ferri-reducing bacteria. This work was carried out on two soil profiles from a small catchment basin in French Guyana, an oxisol (O) from a well drained slope and a water-saturated hydromorphic soil (H). The chemical reductions showed that in the oxisol 20 and 48% of total Hg (HgT) was associated to amorphous and well crystallized iron oxides, respectively. However, in the hydromorphic soil, no Hg seemed to be associated to amorphous iron oxides while the well crystallized fraction contained less than 9% of HgT. Chemical Fe-oxide reduction showed that Hg solubility was correlated to Fe reduction in the oxisol, demonstrating a relationship between the geochemistry of these two metals. During bacterial growth, while bacterial iron reduction solubilised up to 3.2 mg Fe g-1 soil in the oxisol sample, HgT remained unchanged. No mercury was detected in the culture medium either. However, chemical analysis showed a decrease of the amounts of Hg associated to amorphous and well crystallized Fe-oxides after 14 days of incubation, underlining the potential for iron-reducing bacteria to modify mercury distribution in soil.

Mercury distribution in soils and plants surrounding an industrial area in the South of Italy

Soil and plant samples, collected nearby an industrial site in the South of Italy, were investigated to monitor the presence and distribution of mercury (Hg). The Hg contamination in soils ranged from ca. 1.5 to 50 mg kg−1 and was limited to the first 0.5 m. In general, high spatial distribution heterogeneities were observed. The spontaneous flora analysed contained an average of 0.2 mg kg−1 of Hg, and the highest Hg concentration was found in the roots of Glicyrrhiza glabra (0.43 mg kg−1). Hg pollution can be possibly ascribed to a chlor-alkali plant operating in this area in the 1960s-1980s.

Mercury in soils and plants in the area of Lake Bol’shoe Yarovoe ( Altai Territory)

We examined mercury distribution in soils and plants of the catchment area of Lake Bol’shoe Yarovoe with the Altaikhimprom chemical industrial complex situated on its shore. Data on mercury contents show a considerable mercury flow into the environment, though the industrial complex and its waste do not pose serious threat. The revealed pollution in the immediate vicinity of the industrial complex, including that due to atmospheric transport, as well as the elevated content of mercury in hydrochloric and alkaline extracts suggest its intense migration from the waste. Therefore, it is necessary to make up an inventory of the industrial-complex waste and perform a detailed study of the lake ecosystem as a model unit.

Mercury pollution in the atmosphere-soil-biology ecosystem along the trunk road in Guilin

Based on the mercury distribution in soil, atmosphere and plant in seven sections beside the trunk road, some advances are obtained: (1) Mercury content of fuel oil of petrol station in Guilin is 3.66-9.74 ng/g, higher than that reported by other countries (0.7-3.2 ng/g). The higher the number of petrol, the lower the content. Number 90 petrol widely used is the highest (9.74 ng/g). (2) Mercury content in soil is commonly 0.30-0.80 ixg/g near the road, (0.30--2.60 ~tg/g) besides the street, both are higher than the average of Guilin background value (0.204 ~tg/g). Mercury content in vegetable near the road is generally 0.025-0.055 ~tg/g, higher than that far away from the road (0.022-0.038 ~g/g). The content in cinnamon leaves on both sides of the street is 0.064).16 ~tg/g, also higher than that far away from the street (0.051-0.067 ~tg/g). Guilin Highway atmospheric mercury content is usually 7-12 ng/m 3, higher than the mean background value (4.4--6.6 ng/m3). Atmospheric mercury content near rural roads is below the level on urban roads. The atmospheric mercury content increases apparently in traffic-intensive stations and intersections. (3) The average concentration of mercury in vegetables is mostly 0.025-0.055 ~tg/g. Mercury content in various tissues of vegetable follows the order of leaves (mostly 0.044).09 ~tg/g)>roots (mostly 0.02-0.05 ~tg/g)>stems (mostly 0.01-0.04 ~tg/g). (4) The distribution of mercury in soil, plants and atmosphere near the road is of certain similarity, with a single peak, nearly symmetrical. As far away from road, the content reduces gradually, which shows the release of exhaust gas mercury is the main source of atmospheric mercury pollution. (5) The correlation analysis on different types of samples shows the correlation coefficients are 0.404 (atmosphere, vegetable leaves), 0.297 (soil, vegetable leaves), 0.06 (soil, cinnamon leaves) and 0.909 (traffic flow, leaves, respectively). It is suggested atmospheric mercury is the main contributor to mercury in leaves. (6) The atmospheric mercury content before rain is higher than that after rain. The flow status of air has apparent impact on mercury enrichment. (7) The mercury content of postman's hair is 2.968 ~tg/g, it is 2.74 times that of ordinary crowds hair (1.083 ~tg/g). This indicated mercury pollution from exhaust gas can affect ecological environment, and the effect should not be ignored.

Environmental impacts of the abandoned mercury mine in Podljubelj, Slovenia

senik’s tributaries. Each soil and sediment sample consisted of 5 sub-samples. The soil samples were gently crushed, then the fraction smaller than 2 mm was pulverized. In sediment samples we separated different fractions with dry sieving. Fraction smaller than 0,125 mm was analyzed. Analysis for 41 chemical elements was performed by inductively coupled plasma mass spectrometry (ICP-MS) after (total) four-acid digestion (mixture of HClO4, HNO3, HCl and HF at 200°C). Hg was determined by means of cold vapor atomic absorption spectrometry CV-AAS after aqua regia digestion (mixture HCl, HNO3 and water at 95°C). The reliability of analytical procedures was considered adequate for using the determined elemental contents in further statistical analyses. The universal kriging with linear variogram interpolation method (DAVIS, 1986) was applied to construct the maps of spatial distribution of particular elements in soil. For interpolation we considered 41 soil samples (0‐5 cm) from the narrow area of the former mine and smelter. Results The Hg average in soil determined from analyzed samples amounts to 3.04 mg/kg with individual contents ranging between 0.17 and 719 mg/kg. In topsoil Hg concentrations vary from minimum 0.35 to maximum 244 mg/kg with the median of 3.67 mg/kg. The subsoil median is 1.39 mg/kg and individual values between 0.174 and 71.7 mg/kg. The highest determined value (719 mg/kg) was found at the area of former smelter. The concentrations of mercury in soils generally decrease with depth in soil profile and with the distance from the mine. The average enrichment factor in topsoil with respect to subsoil is 3.3. Average contents of Hg in topsoil exceeded the estimated average for soil in Slovenia, which is 0,065 mg/kg (©AJN, 2003), more than 56-times, in subsoil the estimated average was exceeded about 21-times. The areal distribution of mercury in soil (Fig. 1) shows that the mercury halo is limited to the immediate surroundings of the smelter, while away from it the contents rapidly decrease. On an area of about 9 hectares the Hg contents in soil exceed the Slovenian critical value for soil (10 mg/kg). Examination of areal distributions reveals distinct distribution patterns also for Ca, Cd and P, as well as for additional 21 elements. Distributions of the latter may be divided in two groups that reflect the natural elemental distributions in dependence of geochemical composition of the local geology. Group 1 comprises the elements Zr, Th, Hf, K, Ce, La, Na, Rb, W, Ta, Nb, Al and Ba. Their combined distribution exhibits the highest values in the lowest parts of the studied area. The values decrease with altitude above the sea level. High group 1 element values are associated with the B horizon of brown soils on limestones and dolomites. Group 2 comprises the elements Sc, Cr, Ni, Co, Fe, Li, Ti and V. Their combined distribution is characterized by high values in hilly areas, there where the contents of group 1 ele

Mercury distribution in soils, water, atmosphere and vegetables in Zhangzhou City

Mercury distribution in soils, water, atmosphere and vegetables in Zhangzhou City

The Almadén district (Spain): Anatomy of one of the world's largest Hg-contaminated sites

We present data from an early reconnaissance survey (stream sediments, soil, and water Hg chemistry; plants and water crustaceans Hg intake) of the Almadén district (central Spain), that was carried out to establish the potential environmental hazards derived from the anomalous mercury concentrations measured in this realm. The Almadén mercury district (∼300 km 2) can be regarded as the largest geochemical anomaly of mercury on Earth. The district includes a series of mercury mineral deposits, having in common a simple mineralogy (dominant cinnabar: HgS, and minor pyrite: FeS 2). The ore deposits have been mined for more than 2000 years, and the main mine of the district (Almadén), has been active from Roman times to present day with almost no interruptions. The mercury distribution in soils of the district reveals the existence of high, and extremely high mercury values (up to 8889 μg g − 1 ), whereas concentrations in stream sediments and waters reach exceptional values of up to 16,000 μg g − 1 and 11,200 ng l − 1 respectively. On the other hand, very high concentrations of methylmercury (MeHg) have been detected in calcines (up to 3100 ng g − 1 ), sediments (0.32–82 ng g − 1 ), and waters (0.040–30 ng l − 1 ). Mercury gets incorporated to edible river crustaceans and plants. The red swamp crayfish Procambarus clarkii, has Hg concentrations of up to 9060 ng g − 1 (muscle) and 26,150 ng g − 1 (hepatopancreas). Regarding plants, the local wild asparagus ( Asparagus acutifolius) yields values of up to 298 μg g − 1 Hg. Mercury also escapes to the atmosphere, and mineral deposits, together with metallurgical activities, generate strong anomalies of atmospheric Hg. The most important concentrations relate to the emissions from the Almadén metallurgical roaster, in the order of 14,000 ng Hg m − 3 . Additionally, large open pit operations also contribute to the district atmospheric pool of mercury, with high concentrations above 1000 ng Hg m − 3 . Thus, no system (rocks, soils, sediments, waters, atmosphere, biota) in the Almadén district is free from strong Hg contamination.

The effects of land use change on mercury distribution in soils of Alta Floresta, Southern Amazon

Land use change is a strong re-mobilizing agent of Hg distribution in Amazon soils.

A first insight into mercury distribution and speciation in soils from the Almadén mining district, Spain

Almost no environmental data on mercury distribution and speciation in soils have been published so far for the Almadén mining district (central Spain), despite its huge size and historic importance. The mercury distribution in soils of the district reveals the existence of high and extremely high mercury values (up to ∼9000 ppm Hg). The Hg-thermodesorption curves for soils from a decommissioned metallurgical precinct (Almadenejos) and a phytoremediation site show that mercury occurs in the forms of cinnabar and as mercury bound to organic matter. The TEM-EDX study of the highly contaminated anthrosols from Almadenejos (samples with Hg >5000 ppm) shows the existence of cinnabar particles adsorbed to the surface of chlorite grains. Given the generally pyrite-poor character of the ores, and the presence of carbonates in the host rocks, cinnabar solubilization is limited, which in turn mitigates environmental hazards in the district. The only by-product of cinnabar leaching in the mineral dumps is schuetteite (Hg 3SO 4O 2). Preliminary results on local plants ( Asparagus acutifolius, Dittrichia graveolens, Marrubium vulgare) show that mercury gets incorporated to roots, stems and leaves, with values of up to about 300 ppm Hg.

Distribution of mercury in soil and its concentration in runoff from a biosolids-amended agricultural watershed.

Biosolids applications can significantly increase Hg concentrations in cultivated soils. The objective of this study was to quantify levels of mercury in soils and runoff from a biosolids-amended watershed. The study site was a terraced, cultivated watershed that received cumulative biosolids loadings of 0, 87, or 224 Mg ha(-1) between 1974 and 1993. Snowmelt runoff samples were collected from the three treatment areas in the spring of 1995. Soils were collected along transects from the 0 and 224 Mg ha(-1) biosolids treatment areas at depths of 0 to 15 and 15 to 30 cm. Mercury analysis of stored, freeze-dried biosolids samples showed that Hg concentrations during the 20-year study ranged from 12.4 mg kg(-1) initially to 2.4 mg kg(-1) near the end. Soil Hg concentrations were elevated in the surface (0-15 cm) and subsurface (15-30 cm) of the 224 Mg ha(-1) biosolids-treated terrace relative to the control. Mercury concentrations in the 0- to 15-cm soil depth ranged from 30 to 50 microg kg(-1) for the control terrace and 180 to 390 microg kg(-1) for the 224 Mg ha(-1) biosolids-treated terrace. Concentrations were lower in the 15- to 30-cm depth. Total Hg concentrations in snowmelt from the control terrace ranged from 9.2 to 27.9 ng L(-1) and 19.8 to 44.8 ng L(-1) for the biosolids-treated terraces. Most Hg was associated with particulates > 0.45 microm. Mercury concentrations were elevated in grass tissue growing near the watershed's runoff lagoon.