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1.
Historic Hg mining in the Cache Creek watershed in the Central California Coast Range has contributed to the downstream transport of Hg to the San Francisco Bay-Delta. Different aspects of Hg mobilization in soils, including pedogenesis, fluvial redistribution of sediment, volatilization and eolian transport were considered. The greatest soil concentrations (>30 mg Hg kg−1) in Cache Creek are associated with mineralized serpentinite, the host rock for Hg deposits. Upland soils with non-mineralized serpentine and sedimentary parent material also had elevated concentrations (0.9–3.7 mg Hg kg−1) relative to the average concentration in the region and throughout the conterminous United States (0.06 mg kg−1). Erosion of soil and destabilized rock and mobilization of tailings and calcines into surrounding streams have contributed to Hg-rich alluvial soil forming in wetlands and floodplains. The concentration of Hg in floodplain sediment shows sediment dispersion from low-order catchments (5.6–9.6 mg Hg kg−1 in Sulphur Creek; 0.5–61 mg Hg kg−1 in Davis Creek) to Cache Creek (0.1–0.4 mg Hg kg−1). These sediments, deposited onto the floodplain during high-flow storm events, yield elevated Hg concentrations (0.2–55 mg Hg kg−1) in alluvial soils in upland watersheds. Alluvial soils within the Cache Creek watershed accumulate Hg from upstream mining areas, with concentrations between 0.06 and 0.22 mg Hg kg−1 measured in soils 90 km downstream from Hg mining areas. Alluvial soils have accumulated Hg released through historic mining activities, remobilizing this Hg to streams as the soils erode.  相似文献   

2.
Concentrations of total Hg (T-Hg) were measured in mine waste, stream water, soil and moss samples collected from the Tongren area, Guizhou, China to identify potential Hg contamination to local environments, which has resulted from artisanal Hg mining. Mine waste contained high T-Hg concentrations, ranging from 1.8 to 900 mg/kg. High concentrations of Hg were also found in the leachates of mine waste, confirming that mine waste contains significant water-soluble Hg compounds. Total Hg distribution patterns in soil profiles showed that top soil is contaminated with Hg, which has been derived from atmospheric deposition. Data suggest that organic matter plays an important role in the binding and transport of Hg in soil. Elevated T-Hg concentrations (5.9–44 mg/kg) in moss samples suggest that atmospheric deposition is the dominant source of Hg to local terrestrial ecosystems. Concentrations of T-Hg were highly elevated in stream water samples, varying from 92 to 2300 ng/L. Particulate Hg in water constituted a large proportion of the T-Hg and played a major role in Hg transport. Methyl–Hg (Me–Hg) concentrations in the water samples was as high as 7.9 ng/L. Data indicate that Hg contamination is dominantly from artisanal Hg mining in the study area, but the extent of Hg contamination is dependent on the mining history and the scale of artisanal Hg mining.  相似文献   

3.
Five hundred years of mercury (Hg) mining activity in Idrija, Slovenia caused widespread Hg contamination. Besides Hg emissions from the ore smelter, tailings have been found to be the major source of river sediment contamination. In the present study, solid phase binding forms and the aqueous mobility of Hg have been investigated in tailings of the Idrija Hg mine by means of a pyrolysis technique and aqueous Hg speciation. Results show that Hg binding forms differ with the age of the tailings due to the processing of different ores with different roasting techniques. In older tailings, the predominant Hg species is cinnabar (HgS), due to incomplete roasting, whereas in tailings of the 20th century the amount of cinnabar in the material decreased due to a higher efficiency of the roasting process and the increasing use of ores bearing native Hg. In younger tailings, metallic Hg (Hg0) sorbed to mineral matrix components such as dolomite and Fe-oxyhydroxides became the predominant Hg binding form in addition to unbound Hg0 and traces of HgO. Leaching tests show that in younger tailings high amounts of soluble Hg exist in reactive form. In older tailings most of the soluble Hg occurs bound to soluble complexes. It might be assumed that in the long term, matrix-bound Hg0 could be bound to humic acids derived from soils covering the tailings. This means that, despite the lower total Hg concentrations found in the younger tailings, the long-term risk potential of its mobile matrix-bound Hg0 is higher than that of older tailings bearing mostly immobile cinnabar.  相似文献   

4.
Mercury contamination of the environment is of worldwide concern because of its global presence and its potent neurotoxicity. Mining, smelting and the electronics industry are the main sources of Hg pollution. However, few studies have been performed to investigate systemic Hg contamination in metal mining regions. In this study, concentrations of Hg in air, farmland soil, and crops were measured in a Pb-Zn mining area in the karst region of Guangxi, China. Key factors that could affect Hg distribution, such as the fate of waste ore and waste residue, were analyzed. Geo-statistical methods were adopted to analyze the characteristics of spatial structure and distribution of Hg. The results show that Hg contamination in this region is serious. The total mercury (T-Hg) content is far higher than the Level II Limit Value of Chinese Soil Standards of 0.30 mg kg−1, showing obvious directional characteristics from WNW to ESE. Highest Hg concentrations were found in the WNW portion of the study area. The contamination of paddy soil is higher than that in dry farmland soil. The vertical distribution of T-Hg and its decrease with depth suggest that the important sources are waste water irrigation and the improper disposal of the waste ore and waste rock. The T-Hg concentrations in the agricultural products examined exceed the Chinese tolerance value (0.02 mg kg−1 for rice and 0.01 mg kg−1 for vegetables), indicating the seriousness of the problem. The ecological environment and the safety of food grown in this mining area are being affected, with the result that human health is possibly being affected.  相似文献   

5.
《Applied Geochemistry》2003,18(3):371-381
The Nambija Mineral District (NMD) is located in the southeastern part of Ecuador, east of Zamora (Zamora Chinchípe's country), Ecuadorian Amazon. In this district, Au occurrences have been know since colonial and pre-colonial times, but only after the early 1980s has intensive artisanal Au mining activity been developed. Currently, the different NMD Au occurrences continue to be exploited by artisanal operations and are difficult to control in the study area. The environmental impacts due to Au mining are a consequence of the illegal situation and deficiency in controlling the techniques of ore exploitation. The Au extraction is carried out by outdoor amalgamation, so the indiscriminate use of Hg by artisanal miners, associated with careless methods of tailings disposal, has caused occupational exposure and environmental degradation. The present study evaluated the geochemical dispersion and concentrations of local contamination of metallic Hg in soils, stream sediments and mine tailings in the NMD area. This article aims to contribute to the discussion of environmental changes caused by the artisanal Au mining in the Nambija district. A total of 82 samples (32 soil, 40 stream sediment and 10 mine tailings) were analyzed. The results were compared with the Hg levels in soil and stream sediments considered not to be contaminated in the Nambija mining area and in other areas where Hg is mined in the Amazon basin. In this work, mean total Hg (T-Hg) concentrations of 1.7 μg g−1 in soils and 2.7 μg g−1 in stream sediments have been found. Mercury values in the mine tailing samples revealed values ranging from 89 to 1555 μg g−1. The results found for Hg in the different analyzed materials pointed to contamination of the studied area by this metal, while soil erosion is responsible for an increase in stream sediment's T-Hg concentrations in the different aquatic ecosystems of the Nambija Creek and Nambija River.  相似文献   

6.
《Applied Geochemistry》2006,21(11):1924-1939
The Idrija Mine, the second largest Hg mine in the world, ceased operation in 1995, but still delivers large quantities of Hg downstream including into the northern Adriatic Sea, 100 km away. Transformation of Hg species in sediment in sites over 60 km from the mine, including marine sites in the Adriatic Sea, was measured to determine the ability of the system to transform and mobilize Hg and to produce methylmercury (MeHg). Cores from a freshwater impoundment, a brackish estuarine site, and three marine sites in the Gulf of Trieste were sectioned anaerobically, and Hg methylation and MeHg demethylation activities determined using radio-techniques (203Hg for methylation and 14C-MeHg for demethylation). Total and dissolved Hg and MeHg were determined as were other geochemical parameters. In addition, rates of SO4 reduction were determined in marine sediment using a 35S technique. Mercury was readily methylated and demethylated at all sites. Marine sediment was investigated in winter and summer with rates of Hg transformation and SO4 reduction corresponding only in winter. Methylation of Hg in summer displayed subsurface peaks that may have been influenced by bioturbation. Total Hg and MeHg were most abundant in the freshwater, estuarine, and near-shore marine sites, but dissolved pore water Hg and MeHg were highest in the estuarine region where S cycling appeared ideal for the mobilization of Hg. The impoundment sediment also seemed to be a ‘hotspot’ of Hg transformations. MeHg demethylation occurred via the oxidative demethylation pathway (CO2 produced from MeHg), except in surficial sediment offshore in the Gulf during winter, where sediment was more oxidizing and significant amounts of CH4 were liberated during MeHg degradation via reductive demethylation. The CH4 formation was likely due to an increased influence from the expression of MeHg degradative enzymes encoded by the mer detoxification bacterial genetic system. The freshwater site also liberated CH4 from MeHg, but it appeared to be due to oxidative demethylation by methanogenic bacteria.  相似文献   

7.
Trace element concentrations in shallow marine sediments of the Buyat-Ratototok district of North Sulawesi, Indonesia, are affected by submarine disposal of industrial gold mine tailings and unregulated dumping of tailings and wastewater from small-scale gold mining using mercury amalgamation. Industrial mine tailings contained 590–690 ppm arsenic, 490–580 ppm antimony, and 0.8–5.8 ppm mercury. Tailings-affected sediment As and Sb concentrations were 20–30 times higher than in muddy sediments not contaminated with tailings, and 50–60 times higher than pre-mining average. Highest mercury concentrations were observed in sediments affected by small-scale mining using mercury amalgamation (5–29 ppm). Concentrations of most other trace elements were comparable in sediments affected by both types of mining and were slightly higher than regional averages for sediments collected before the onset of industrial mining. Elevated concentrations of both As and Sb in approximately equal proportions suggest tailings dispersal of at least 3.5 km. Mercury released from artisanal gold mining dispersed up to 4 km from river mouths. Slight increases in concentrations of non-mercury trace elements in areas affected by artisanal mining over pre-industrial mining concentrations were probably caused by increased rates of erosion. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   

8.
The Xunyang Hg mine (XMM) situated in Shaanxi Province is an active Hg mine in China. Gaseous elemental Hg (GEM) concentrations in ambient air were determined to evaluate its distribution pattern as a consequence of the active mining and retorting in the region. Total Hg (HgT) and methylmercury (MeHg) concentrations in riparian soil, sediment and rice grain samples (polished) as well as Hg speciation in surface water samples were measured to show local dispersion of Hg contamination. As expected, elevated concentrations of GEM were found, ranging from 7.4 to 410 ng m−3. High concentrations of HgT and MeHg were also obtained in riparian soils, ranged from 5.4 to 120 mg kg−1 and 1.2 to 11 μg kg−1, respectively. Concentrations of HgT and MeHg in sediment samples varied widely from 0.048 to 1600 mg kg−1 and 1.0 to 39 μg kg−1, respectively. Surface water samples showed elevated HgT concentrations, ranging from 6.2 to 23,500 ng L−1, but low MeHg concentrations, ranging from 0.022 to 3.7 ng L−1. Rice samples exhibited high concentrations of 50–200 μg kg−1 in HgT and of 8.2–80 μg kg−1 in MeHg. The spatial distribution patterns of Hg speciation in the local environmental compartments suggest that the XMM is the source of Hg contaminations in the study area.  相似文献   

9.
Shallow marine sediments of the Buyat-Ratototok district of North Sulawesi, Indonesia, are affected by submarine disposal of industrial gold mine tailings and small-scale gold mining using mercury amalgamation. Industrial mine tailings contained 590–660 ppm arsenic, 490–580 ppm antimony, and 0.8–5.8 ppm mercury. Electron microprobe survey found both colloidal iron–arsenic-phases without sulphur and arsenian pyrite in tailings and sites to which tailings had dispersed, but only arsenopyrite in sediments affected by artisanal mining. Antimony in tailings was present as antimony oxides, colloidal iron–antimony phases, colloidal iron–antimony phases, and stibnite in sediments affected by both types of mining. A sequential extraction found that 2% of arsenic held in tailings and tailings-contaminated sediments was exchangeable, 20–30% was labile, including weakly adsorbed, carbonate- and arsenate bound, 20–30% was metastable, probably incorporated into iron or manganese oxyhydroxides, or strongly adsorbed to silicate minerals, and 40–48% was relatively insoluble, probably incorporated into sulphides or silicates. Arsenic in sediments affected by artisanal gold mining was 75–95% relatively insoluble. Antimony in all sediments was >90% relatively insoluble. Relative solubility patterns of most other metals did not differ between industrial tailings-affected, artisanal-mining affected areas, and fluvial sediments. Results suggest that submarine tailings disposal is not suitable for refractory Carlin-like gold deposits because ore processing converts arsenic to forms unstable in anoxic marine sediments. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.  相似文献   

10.
Mercury (Hg) is one of the elements with increasing environmental significance. A total of 22 samples (soils, rocks and gels) were collected along a 6 km transect around the Valdeazogues River valley in the southwest of the Iberian Peninsula (Almadén, Spain). Samples were characterized by different soil types of depositional sequences associated with mining tailings, type and system tracts: 15 surface soil samples included in the transect; 3 of a Haploxerept soil profile developed on slates; 2 of quartzite and slates rocks (reference rocks in the area). Moreover, two of a gel substance (in the lower tract of the river). Soil samples were analyzed for Hg, Cu, Ni, Cr, V, Pb, Cd and As, as well as for organic matter, pH abrasion and calcium carbonate content. All samples were collected from the Almadén mining district. The level of occurrence of the elements (especially Hg) and the effect of some properties on its concentration distributions were investigated. The total mercury contents varied in the range 7,315–3.44 mg kg−1. The mean concentration of total mercury in soils and rocks was 477.03 mg kg−1dry mass. This value is very high compared to the regional background value of other areas. Only rarely is it higher than 1%: in one sample (7,315 mg kg−1) it was almost eight times in comparison with the affected zones, with a high value of 1,000 mg kg−1. Significant differences between samples were found in the total content of mercury. A large percentage of the samples registered detectable levels of V, Cr, Ni, Pb, As and Cu. Cd readings were below the detectable range for all samples tested. Cr mean concentration was 216.95 mg kg−1 (minimun concentration 86, maximun 358); V mean concentration was 119.09 mg kg−1 (minimun concentration 69, maximun 1,209); As mean concentration was 51.24 mg kg−1 (minimun 13.3 and maximun 319.4); Ni mean concentration was 45.64 mg kg−1 (minimun concentration 21.2 and maximun 125.6); Cu mean concentration was 33.25 mg kg−1 (minimun concentration 19.3 and maximun 135); Pb mean concentration was 15.19 mg kg−1 (minimun 1.12 and maximun 1013). Metal distribution generally showed spatial variability ascribed to significant anthropogenic perturbation by mining tailing type. Hg showed vertical profile characterized by surface enrichment, with concentrations in the upper layer (93.7–82.2 mg kg−1 in front of 3.4 of the rock value) exceeding, in several occasions, the background value. The results obtained denote a potential toxicity of some heavy metals in some of the studied samples. Water-soluble mercury could enter the aquatic system and accumulate in sediments. Mercury and other heavy metals contamination depended on the duration and intensity of mining activities.  相似文献   

11.
Within the management hierarchy of municipal solid waste (MSW), incineration with energy recovery is a desired and viable option often used in densely populated and economically developed cities. The gaseous and particulate mercury (Hg) emitted from MSW incinerators may accumulate in the soil entering via dry and wet deposition. To investigate the soil Hg level and estimate the effects of the local meteorological and topographical characteristics (e.g., winds and terrain) on the soil Hg distribution, two layers of soil samples around an MSW incinerator in Shenzhen, China were collected and analyzed. Results showed that the Hg levels ranged from 0.012 to 0.136 mg kg−1 and from 0.013 to 0.100 mg kg−1 in the surface and subsurface soils, respectively. Long-term exposure of the soil to atmospheric Hg from the MSW incinerator dominates the spatial pattern of soil Hg. The wind frequency directly affected Hg distribution but not decisively. Interestingly, the variations of Hg level with downwind distance away from the stack were highly consistent with the terrain profile (r 2: 0.412–0.748). The effects of winds and terrain on soil Hg distribution and their mechanisms are discussed and general Hg dispersion patterns for transport on terrain are further proposed.  相似文献   

12.
The Idrija mine was the second largest Hg mine in the world surpassed only by the Almaden mine in Spain. It has been estimated that almost 145,000 tons of Hg was produced during operation (1490-1995) of the mine. In the first decade of Hg mining in Idrija the ore was roasted in piles; after that it was roasted for 150 years, until 1652, in earthen vessels at various sites in the woods around Idrija. Pšenk is one out of 21 localities of ancient roasting sites established on the hills surrounding Idrija and one of the largest localities of roasting vessel fragments. The unique way of roasting very rich Hg ore at this site has resulted in soil contamination and considerable amounts of waste material that potentially leach Hg into the surrounding environment. The main aim of this study was to determine the distribution and the forms of Hg in contaminated soils in order to evaluate potential environmental risk. Detailed soil sampling was performed on 37,800 m2 area to establish the extent of Hg pollution and to investigate Hg transformations and transport characteristics through the 400 a-long period. A total of 156 soil (0-15 cm and 15-30 cm) and SOM (soil organic matter) samples were collected from 73 sampling points. Three soil profiles were sampled to determine vertical distribution of Hg. The main Hg phases were determined by the Hg-thermo-desorption technique. The measured Hg contents in soil samples in the study area vary from 5.5 to almost 9000 mg/kg with a median of 200 mg/kg. In SOM, Hg contents range from 1.4 to 4200 mg/kg with a median of 20 mg/kg. Extremely high Hg contents were found in soil profiles where the metal reaches 37,020 mg/kg. In general, Hg concentrations in all three profiles show a gradual decrease with depth with the minimum values between 140 mg/kg and 1080 mg/kg. The Hg-thermo-desorption curves indicate the presence of Hg in the form of cinnabar and that of Hg bound to organic or mineral soil matter. The distribution of Hg species in soil and SOM samples show almost equal distribution of cinnabar and non-cinnabar Hg compounds. The non-cinnabar fraction shows a little increase with depth, but cinnabar represents a high portion of total Hg (about 40%). Large amounts of potentially mobile and transformable non-cinnabar Hg compounds exist at the roasting site, which are potentially bioavailable.  相似文献   

13.
The fate of the arsenic (As) under neutral hydrogeochemical conditions in the mining ecosystem has attracted increasing concern, as the ecological restoration of As provides a possibility for safe use of mine water. However, successful cases are still inadequately reported worldwide. Therefore, to investigate the As-behavior in the mine tailings ecosystem, a study of the Wanniangou tailings pond (regional largest V-Ti-Fe mine tailings pond, Sichuan province, China) and the downstream (Rehe River) was conducted. It involves hydro-geochemistry, mineralogy, biogeochemistry, and the Geographically Weighted Regression model (GWR). The results reveal that: (1) the pH range of the mine water is 6.32 to 7.21. The chemical weathering of tailings resulted in an abnormal As concentration in water (e.g., transport pipe wastewater 76.5 μg L−1, the outlet of tailings pond 28.4 μg L−1), and it declines to the national water quality guideline (<10 μg L−1) after 2.59 km from the pond outlet. (2) Although sulfide oxidation boosts As migration in the tailings, As ecological refixation is promoted by tailings particle percolation, river sediment absorption, and aquatic plant uptake. The As refixation behaviors vary spatially, corresponding with the diversity of precipitation and absorption. Besides, Manganese (oxides or/and hydroxides) is conducive to As coprecipitation in the neutral hydrogeochemical environment. (3) The site selection of the V-Ti-Fe mine tailings pond with a downstream longer than 3 km creates a toxic metals self-restoration buffer zone, which could relieve the contamination probability and make the mining wastewater re-utilization feasible.  相似文献   

14.
陕西潼关金矿区泥石流潜势度评价   总被引：10，自引：0，他引：10  
陕西潼关金矿区位于小秦岭北坡，区内发生的泥石流灾害，其物源90％是采矿弃渣。本文选择采矿弃渣量、纵坡降比、渣堆补给长度与沟长比、沟岸山坡坡度、河流弯曲程度、河流堵塞情况、渣堆稳定性、流域面积、历史上有无泥石流灾害发生等9个泥石流发生的因子，在给定因子权重排序的基础上，采用因子权值与因子赋值相乘后相加的方法，求得18条沟谷泥石流潜势度指数及其排序。在降雨量相同的条件下，潜势度指数可似比风险度指数。  相似文献   

15.
The Pb sorption capacity of apatite ore mine tailings and its potential to act as a remediation agent in a Pb polluted areas were investigated. The tailings, originating from the Siilinjärvi carbonatite complex in Finland, consist mainly of phlogopite and calcite accompanied by apatite residues. The ability of the tailings to retain Pb from an aqueous solution was investigated using an isotherm technique. Furthermore, in a 3-month incubation experiment, uncontaminated mineral soil was amended with untreated tailings and with tailings artificially weathered with acid to increase the quantity of Al and Fe (hydr)oxides. Tailings of two particle-sizes (∅ > 0.2 mm and ∅ < 0.2 mm) somewhat differing in their mineralogical composition were investigated as separate amendments. All tailings materials were added to the soil in two dosages (5 g and 10 g of tailings per 125 g of soil). Following incubation, tailings-induced changes in the Pb sorption capacity of the soil were investigated with the isotherm technique. Finally, to investigate the distribution of sorbed Pb among various chemical pools, the soil samples amended with tailings were contaminated with Pb and then subjected to sequential fractionation analysis. The results revealed efficient removal of Pb from an aqueous solution by the tailings, presumably through precipitation and surface complexation mechanisms. Amending the soil with the tailings increased the mass-based maximum Pb sorption capacity from 10.8 mg kg−1 of the control soil to 14–20.5 mg kg−1 for the untreated tailings and to 32.1–72.1 mg kg−1 for the acid-treated material. The tailings transferred Pb from the exchangeable pool to the non-extracted one and thereby substantially decreased its bioavailability. The material with a particle diameter of less than 0.2 mm had a higher mass-based Pb sorption capacity than the large-sized material. The results suggest that the tailings may potentially serve as an immobilizing agent in polluted areas.  相似文献   

16.
Although fish in Dorena Lake are contaminated with mercury, the source of pollution in the watershed was unconfirmed until the present study. To trace the mercury to its source, fine-grained sediment samples were collected from the major streams of the watershed. A few samples of mine waste/tailings were also obtained from the Bohemia Mining District where mercury was historically used in processing gold and silver ore. Mercury concentrations in sediment from streams that do not drain the central mining district average 0.066 ppm, whereas samples taken downstream of the district contain 0.140-1.339 ppm. Mine waste/tailings contain 13.441 to >50 ppm mercury. The source of mercury contamination in the Dorena Lake watershed is thus the Bohemia Mining District. Historical and geological evidence strongly suggests that the mercury problem in the district resulted from gold-mercury amalgamation practices, but naturally high mercury content in mineralized areas cannot be ruled out with the data presented here.  相似文献   

17.
Forests play a primary role in the cycling and storage of mercury (Hg) in terrestrial ecosystems. This study aimed to assess differences in Hg cycling and storage resulting from different vegetation at two adjacent forest stands - beech and spruce. The study site Načetín in the Czech Republic's Black Triangle received high atmospheric loadings of Hg from coal combustion in the second half of the 20th century as documented by peat accumulation rates reaching 100 μg m−2 y−1. In 2004, the annual litterfall Hg flux was 22.5 μg m−2 y−1 in the beech stand and 14.5 μg m−2 y−1 in the spruce stand. Soil concentrations and pools of Hg had a strong positive relation to soil organic matter and concentrations of soil sulfur (S) and nitrogen (N). O-horizon Hg concentrations ranged from 245 to 495 μg kg−1 and were greater in the spruce stand soil, probably as a result of greater dry Hg deposition. Mineral soil Hg concentrations ranged from 51 to 163 μg kg−1 and were greater in the beech stand soil due to its greater capacity to store organic carbon (C). The Hg/C ratio increased with depth from 0.3 in the O-horizon to 3.8 μg g−1 in the C horizon of spruce soil and from 0.7 to 2.7 μg g−1 in beech soil. The Hg/C ratio was greater at all mineral soil depths in the spruce stand. The organic soil Hg pools in beech and spruce stands (6.4 and 5.7 mg m−2, respectively) were considerably lower than corresponding mineral soil Hg pools (39.1 and 25.8 mg m−2). Despite the important role of S in Hg cycling, differences in soil Hg distribution at both stands could not be attributed to differences in soil sulfur speciation.  相似文献   

18.
Macquarie Harbour in southwest Tasmania, Australia, has been affected severely by the establishment of mines in nearby Queenstown in the 1890s. As well as heavy metal-laden acid rock drainage from the Mount Lyell mine area, over 100 Mt of mine tailings and slag were discharged into the Queen and Ring Rivers, with an estimated 10 Mt of mine tailings building a delta of ca. 2.5 km2 and ca. 10 Mt of fine tailings in the harbour beyond the delta. Coring of sediments throughout Macquarie Harbour indicated that mine tailings accreted most rapidly close to the King River delta source with a significant reduction in thickness of tailings and heavy metal contamination with increasing distance from the King River source. Close to the King River delta the mine tailings are readily discriminated from the background estuarine sediments on the basis of visual logging of the core (laminations, colour), sediment grain size, sediment magnetic susceptibility and elemental geochemistry, especially concentrations of the heavy metals Cu, Zn and Pb. The high heavy metal concentrations are demonstrated by the very high contamination factors (CF > 6) for Cu and Zn, with CF values mostly >50 for Cu for the mine-impacted sediments. Although the addition of mine waste into the King River catchment has ceased, the catchment continues to be a source of these heavy metals due to acid rock drainage and remobilisation of mine waste in storage in the river banks, river bed and delta. The addition of heavy metals to the harbour sourced from the Mount Lyell mines preceded the advent of direct tailings disposal into the Queen River in 1915 with the metals probably provided by acid rock drainage from the Mount Lyell mining area.  相似文献   

19.
Copper contamination in soils and vegetables in the vicinity of an abandoned copper mine in China was investigated. The Cu concentrations of 93 soil samples ranged from 30.4 to 3,191 mg kg−1 soil for a mean of 816.8 mg kg−1 soil. Among 15 samples from a 0 to 20-cm soil layer used for the toxicity characteristic leaching procedure (TCLP) test, the highest value of Cu-TCLP was 133.8 mg kg−1 soil and the TCLP values were positively correlated with the total Cu content of the soils. The sequential extraction of soils in the 0–20-, 20–40-, and 40–60-cm soil layers showed that Cu existed mainly in the Fe–Mn oxide fraction, sulfide/organic fraction, and residual fraction. The copper contamination of 21 species of vegetables from in situ sampling was also examined. Cu concentrations in the edible portions of Brassica chinensis and Solanum melongena were higher than the FAO/WHO standard (40 mg kg−1 DW). The health risk of copper for local inhabitants from consuming these vegetables was assessed on the basis of the target hazard quotient. Enriched concentrations of copper were also found in situ in eight cultivars of B. chinensis planted in the fields, with two levels of Cu concentration. The results showed that there is severe copper contamination in this mine area, and the pollutant in soils show a high risk of leaching into the groundwater and diffusing through the food chain.  相似文献   

20.
The influence of geomorphological factors to Hg contamination of the Idrijca River alluvial sediments because of the historical mining and ore roasting activities has been studied. Main source of Hg in alluvial sediments was dumping of ore roasting residues and mining waste into the river channel and its erosion downstream. The position of the material in relation to the geomorphological properties is highly related with its Hg content. Floodplains were found to be the most contaminated geomorphological units (mean Hg content 335 mg/kg), with Hg concentration rapidly dropping in the first terrace (155 mg/kg). The least contaminated material was found in the higher terraces (3.8 mg/kg). Sampling upstream Idrija (average Hg content is 22.1 mg/kg) shows that not only mine and ore roasting plant increased Hg levels in alluvial deposits but also contaminated sites upstream Idrija contribute to Hg contamination. Geochemical background for alluvial sediments for this area is estimated to be 0.75 mg/kg. Downstream Idrija, 9 hotspots were determined where highly contaminated material is actively eroded and carries a high risk of further contamination of the So?a River and northern Adriatic Sea ecosystems.  相似文献   

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