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1.
Vegetation at mining sites can produce increased heavy metal leaching by the organic acids and protons originating from root secretion and litter degradation. Batch experiments were conducted to investigate the effects of organic acids and pH on the extraction of Pb, Cd, Zn and Cu from an alkaline mine soil (sampled from a mining site of Chenzhou City, Hunan Province) and an acid mine soil (sampled from a mining site of Daxin county, Guangxi Province). The results showed that in the presence of organic acids (acetic, oxalic, malic, fumaric, tartaric and citric acids) at pH 7, the extraction of Pb, Cd, Zn and Cu from the acid mine soil was much higher than that from the alkaline mine soil, in which only citric acid with higher concentration was capable of extracting some heavy metals. Citric acid had the strongest ability in extracting heavy metals, followed by oxalic acid. Heavy metal extraction dramatically decreased with increasing pH. Moreover, at low pH, oxalic acid promoted the risk of Cu leaching; at high pH, the leaching of Pb, Zn, Cd and Cu was enhanced by both oxalic and citric acids. This indicated that those plants, which can produce substantial citric acid or oxalic acid by root secretion and litter degradation, should not be selected for the revegetation of mining sites.  相似文献   

2.
Several abandoned Cu mines are located along the shore of Prince William Sound, AK, where the effect of mining-related discharge upon shoreline ecosystems is unknown. To determine the magnitude of this effect at the former Beatson mine, the largest Cu mine in the region and a Besshi-type massive sulfide ore deposit, trace metal concentration and flux were measured in surface run-off from remnant, mineralized workings and waste. Samples were collected from seepage waters; a remnant glory hole which is now a pit lake; a braided stream draining an area of mineralized rock, underground mine workings, and waste piles; and a background location upstream of the mine workings and mineralized rock. In the background stream pH averaged ∼7.3, specific conductivity (SC) was ∼40 μS/cm, and the aqueous components indicative of sulfide mineral weathering, SO4 and trace metals, were at detection limits or lower. In the braided stream below the mine workings and waste piles, pH usually varied from 6.7 to 7.1, SC varied from 40 to 120 μS/cm, SO4 had maximum concentrations of 32 mg/L, and the trace metals Cu, Ni, Pb, and Zn showed maximum total acid extractable concentrations of 186, 5.9, 6.2 and 343 μg/L, respectively.  相似文献   

3.
Mine tailings are ubiquitous in the landscapes of mined areas. Metal solubilities were compared in two chemically distinct mine tailings from the old Mining District of Cartagena-La Unión (SE Spain). One of the tailings was acidic (pH 3.0) with 5400 mg/kg Zn, 1900 mg/kg As and 7000 mg/kg Pb. The other was neutral (pH 7.4) with 9100 mg/kg Zn, 5200 mg/kg Pb and 350 mg/kg As. In samples from the acidic tailings, more than 15% of the Zn and 55% of the Cd were extractable with 0.1 M NaNO3, and distilled water. In the neutral tailings, using the same reagents, less than 1% of the metals were extractable. A sequential extraction procedure revealed that the sum of the residual and the Fe oxide fractions of Cu, Zn and Pb comprised 80–95% in the acidic tailings and 70–90% in the neutral tailings. The acidic mine tailings had a higher metal solubility, resulting in more metal leaching in the short-term, but also a higher fraction of inert metal. In contrast, in the neutral tailings, the metals were evenly distributed between, oxides and the residual fraction. This implies lower metal mobility in the short-term, but that metal mobility may increase in the long-term. When applied to mine tailings, sequential extractions may provide misleading results because the strong cation exchange capacity of some extractants may induce pH changes and thereby significantly change metal solubility.  相似文献   

4.
The speciation and mobility of some selected trace metals (As, Cu, Mn, Pb and Zn) in sediments with depth was investigated in the Cam River-mouth (Vietnam) by collecting sediment cores and analysing porewater and sediment composition, complemented with single (ammonium-EDTA) and sequential (BCR 3-step) extractions and mineralogical analysis (XRD). All trace metals show overall decreasing trends with depth in porewater as a result of anthropogenic input in upper sediment layers. High porewater concentrations of As, Mn and Pb in oxic and suboxic sediment layers may result in groundwater pollution. Sediment-bound Pb and Mn dominate in the reducible and the acid-soluble fraction, respectively, while Cu and Zn distribute rather evenly between four extracted fractions. The porewater metal speciation, as predicted by a geochemical model Visual MINTEQ version 3.0, indicates that the toxicity of Cu, Mn, Pb and Zn (presented by the proportions of free metal ions) decreases with depth, while the toxicity of As increases when As(III) becomes more abundant. The dissolved concentrations of trace metals are not only controlled by the precipitation/dissolution of discrete hydroxide/oxide, carbonate and phosphate minerals, but also by sorption processes on major sorbents (i.e. As on goethite, and Mn and Zn on calcite and dolomite). Sulphide minerals do not show any control even in the anoxic zone most likely because of the low concentration of sulphur.  相似文献   

5.
The aim of the study was to determine whether the application of phosphate compounds (phosphorite rock, phosphate fertilizer) to polyminerallic waste rocks can inhibit sulfide oxidation and metal mobility (Cu, Pb, Zn, Cd, Ni, Mn, Mg). Waste rocks comprised sulfidic carbonaceous shales and were sourced from the Century Pb-Zn mine, NW Queensland, Australia. The acid producing, Pb-Zn rich rocks consisted of major quartz, muscovite/illite, dolomite, siderite and kaolinite as well as smaller amounts of sulfide minerals (e.g. galena, sphalerite, pyrite). Laboratory leach experiments were conducted on finely granulated phosphate-treated waste rocks (>2 to <30 mm) over 13 weeks, whereas phosphate amendment of coarsely granulated waste rocks (sand to boulder size) was investigated using heap leach piles at the mine site over an 11 months period. Results of the laboratory experiments demonstrate that the treatment of finely granulated waste rocks with phosphorite rock produced leachates with near-neutral pH values due to calcite dissolution. This in turn did not allow the leaching of apatite, formation of secondary phosphate phases and phosphate stabilization to occur. Metal mobility in these amended wastes was restricted by the dissolution of calcite and the resultant near-neutral pH conditions. By contrast, the application of the water-soluble phosphate fertilizer MKP (KH2PO4) to polyminerallic sulfidic waste rocks during the short-term laboratory experiments led to the formation of phosphate coatings and precipitates and inhibited acid and metal release (Cd, Mn, Ni, Pb, Zn). At least in the short term, the application of phosphate fertilizers proved to be an effective method. However, results of the long-term field trials demonstrate that coarsely granulated waste rocks were not coated by secondary phosphate phases and that amendment by phosphorite rock or superphosphate fertilizer did not improve leachate quality compared to the unamended waste. Thus, phosphate stabilization appears ineffective in suppressing oxidation of sulfides in coarsely granulated mine wastes.  相似文献   

6.
The concentration and distribution of metals were studied in metallophytes, growing on and in the vicinity of Pb–Zn gossans, NW Queensland. The study investigated the accumulation of metals in plant species and assessed their potential use as indicators in geobotanical and biogeochemical prospecting and as metal excluders in mine site rehabilitation. Plant species colonising the gossans tolerate high concentrations of metals. Total mean metal concentrations of soils ranged from minima of 14 ppm Cu, 28 ppm Pb and 34 ppm Zn in background areas to maxima of 660 ppm Cu, 12000 ppm Pb and 2100 ppm Zn over mineralised soils. Over the gossans, the grass species Eriachne mucronata forma, Enneapogon lindleyanus and Paraneurachne muelleri replace the characteristic grass Triodia molesta where the soils have high Pb and Zn concentrations. Of the 16 plant species identified, 3 of them, Hybanthus aurantiacus, Clerodendrum tomentosum and Bulbostylis barbata, were confined to the gossan sites. B. barbata appears to be of particular use in geobotanical prospecting as it indicates base metal mineralisation in the region.  相似文献   

7.
Trace metals in soils may pose risks to both ecosystem and human health, especially in an urban environment. However, only a fraction of the metal content in soil is mobile and/or available for biota uptake and human ingestion. Various environmental availabilities of trace metals (Cu, Pb and Zn) in topsoil from highly urbanized areas of Hong Kong to plants, organisms, and humans, as well as the leaching potential to groundwater were evaluated in the present study. Forty selected soil samples were extracted with 0.11 M acid acetic, 0.01 M calcium chloride, 0.005 M diethylenetriaminepentaacetic acid, and simplified physiologically based extraction tests (PBET) for the operationally defined mobilizable, effectively bioavailable, potentially bioavailable, and human bioaccessible metal fractions, respectively. The metals were generally in the order of Zn > Cu ∼ Pb for both mobility (24%, 7.6%, 6.7%) and effective bioavailability (2.8%, 0.9%, 0.6%), Pb (18%) > Cu (13%) > Zn (7.4%) for potential bioavailability, and Pb (59%) ∼ Cu (58%) > Zn (38%) for human bioaccessibility. Although the variations in the different available concentrations of metals could mostly be explained by total metal concentrations in soil, the regression model predictions were further improved by the incorporation of soil physicochemical properties (pH, OM, EC). The effectively bioavailable Zn and Pb were mostly related to soil pH. Anthropogenic Pb in urban soils tended to be environmentally available as indicated by Pb isotopic composition analysis. Combining various site-specific environmental availabilities might produce a more realistic estimation for the integrated ecological and human health risks of metal contamination in urban soils.  相似文献   

8.
The removal efficiency of water hyacinth for Zn, Cu, Pb and Cd after their entry into an undisturbed fresh water body was studied using minicosms placed within a reservoir. Variable parameters were water pH (6 or 8), single or multi-metal additions, and the plant biomass. The initial concentrations of Zn, Cu, Pb and Cd in water (500, 250, 250 and 50 μg/L, respectively) quickly decreased in the order Pb ≈ Cu ? Cd ≈ Zn in the first days. Metal removal was more efficient at pH 8 than at pH 6, and it was only slightly higher for single metals compared to multi-metal additions. After 8 days the remaining amounts of metals relative to their initial concentrations for multi-metal pollution treatments were 8% and 24% (Cu), 11% and 26% (Pb), 24% and 50% (Cd), and 18% and 57% (Zn) at pH 8 and pH 6, respectively. Increasing plant biomass promoted faster metal removal. The bioconcentration factor (the ratio of the metal concentration in whole plants to the initial metal concentration in water) exceeds 2000 for all metals (with the exception of Zn and Cd at pH 6). It was concluded that the water hyacinth can be successfully used for fast removal of metals in the initial stage of water body remediation.  相似文献   

9.
Dissolved and particulate concentrations of metals (Fe, Al, Mn, Co, Ni, Cu, Zn, Cd, Tl, Pb) and As were monitored over a 5 year period in the Amous River downstream of its confluence with a creek severely affected by acid mine drainage (AMD) originating from a former Pb–Zn mine. Water pH ranged from 6.5 to 8.8. Metals were predominantly in dissolved form, except Fe and Pb, which were in particulate form. In the particulate phase, metals were generally associated with Al oxides, whereas As was linked to Fe oxides. Metal concentrations in the dissolved and/or particulate phase were generally higher during the wet season due to higher generation of AMD. Average dissolved (size < 0.22 μm) metal concentrations (μg/L) were 1 ± 4 (Fe), 69 ± 49 (Al), 140 ± 118 (Mn), 4 ± 3 Co, 6 ± 4 (Ni), 1.3 ± 0.8 (Cu), 126 ± 81 (Zn), 1.1 ± 0.7 (Cd), 0.9 ± 0.5 (Tl), 2 ± 3 (Pb). Dissolved As concentrations ranged from 5 to 134 μg/L (30 ± 23 μg/L). During the survey, the concentration of colloidal metals (5 kDa < size < 0.22 μm) was less than 25% of dissolved concentrations. Dissolved metal concentrations were generally higher than the maximum concentrations allowed in European surface waters for priority substances (Ni, Cd and Pb) and higher than the environmental quality standards for other compounds. Using Diffusion Gradient in Thin Film (DGT) probes, metals were shown to be in potentially bioavailable form. The concentrations in Leuciscus cephalus were below the maximum Pb and Cd concentrations allowed in fish muscle for human consumption by the European Water Directive. Amongst the elements studied, only As, Pb and Tl were shown to bioaccumulate in liver tissue (As, Pb) or otoliths (Tl). Bioaccumulation of metals or As was not detected in muscle.  相似文献   

10.
The chemical associations of Cd, Cu, Pb, and Zn in four mine soil samples from the Amizour-Bejaia Pb/Zn mine (Algeria) have been investigated by a five-step sequential extraction procedure. Although Cd preferentially binds to carbonates, Cu, Pb, and Zn are mainly associated with the organic and reducible fractions. Batch adsorption experiments with either mono- or multi-metallic solutions are described with the Freundlich isotherm model. Whatever the nature of the soil sample, the sorption behavior for each given metal except Pb is very similar, indicating that the binding sites at the soil surface are progressively occupied by the metal from the solution. On each soil sample, the decreasing order of sorption can be established as Pb >> Cu > Cd > Zn. When the four metals are simultaneously applied to each soil sample, their specific behavior is strongly affected by their interactions and/or competition for the available surface sites: we generally observed isotherm curves with a slight maximum before the plateau at higher solution concentration. Although Cu is only slightly affected by the other metals, in the case of Pb, Cd, and Zn, the sorbed amounts strongly decreased.  相似文献   

11.
The Sarcheshmeh is one of the largest Oligo-Miocene porphyry Cu deposits in the world. Comparative hydrochemical, mineralogical and chemical fractionation associated with mining efflorescence salts and processing wastes of this mine are discussed. Hydrochemical results showed that rock waste dumps, reject wastes and old impoundments of tailings are the main sources of acid mine drainage waters (AMD) that contain potentially toxic metals such as Cd, Co, Cu, Mn, Ni and Zn as well as Al. Episodic fluxes of highly contaminated acidic waters were produced in a tailings dam over a short period of time. Secondary soluble minerals provide important controls on the quality of AMD produced, especially in old, dry tailings impoundments. Secondary sulfate minerals such as gypsum, magnesiocopiapite, hydronium jarosite, kornelite and coquimbite were found in rock waste drainages and in old weathered reject wastes. Highly soluble secondary minerals such as gypsum, eriochalcite, and bonattite are also observed in an evaporative layer on old tailings impoundments. Chemical fractionation patterns of potentially toxic elements showed that the geochemical behavior of metals is primarily controlled by the mineralogical composition of waste samples. Elements such as Co, Cr, Cu, Mn, Ni and Zn are readily released into the water soluble fraction from efflorescence salts associated with rock waste drainages, as well as from the evaporative layer of old tailings. Potentially toxic elements, such as As, Mo and Pb, are principally adsorbed or co-precipitated with amorphous and crystalline Fe oxides, but they may also be associated with oxidizing, primary sulfides and residual fractions. Following the development of the dammed tailings pond, the secondary minerals were dissolved, producing acidic waters contaminated by Al (154 mg L−1), Cu (150 mg L−1), Cd (0.31 m gL−1), Co (2.13 mg L−1), Mn (73.7 mg L−1), Ni (1.74 mg L−1), Zn (20.3 mg L−1) and Cl (1690 mg L−1). Therefore, the potential use of recycled water from the Sarcheshmenh dammed tailings pond is diminished by the presence of corrosive ions like Cl− in highly acidic fluids that promote corrosion of pipes and pumps in the water recycling system.  相似文献   

12.
Rio Marina mining district (Elba Island) is characterised by hematite + pyrite ore association and was exploited for iron till 1981, leaving waste rock dumps of several millions m3. The effect of open pit mining activity in this site is to produce acid mine drainage (AMD) processes leading to environmental pollution, testified by all the sampled waters (Giove stream, drainage channels, superficial pools and settling basin) which have pH values ranging from 2.08 to 3.35 and heavy metal concentrations that reach 903.16 mg/l for Fe, 45.02 mg/l for Mn, 10.08 mg/l for Zn and 1.75 mg/l for Cu. In the present work a space and time related approach to geochemical hazard evaluation was applied. The geochemical hazard is mainly related to high heavy metal concentration, acid mine drainage processes development and topographic setting. As all these parameters are related in space, hazard evaluation was performed by geostatistical methods. Fifty-four earth material samples (residual soils, waste rocks or debris materials) were collected in a central aligned 100 m mesh square grid. These were analysed for major elements by XRF, for Cu, Pb, Zn by ICP-AES and for AMD potential following the AMIRA procedure. The concentration of heavy metals was compared with Italian law limits. The overlap of Cu, Pb and Zn content maps show that at least one of these heavy metals exceed law limits in all the area. The AMD test results show that more than 50% of samples have a positive NAPP (Net Acid Producing Potential) that could reach 258.9 kg H2SO4/t. According to the obtained data, three main geochemical hazard classes were established and their distribution in the mining area was assessed. About 51% of the mining area surface belongs to the major hazard class, where AMD process occurs, about 49% belongs to an intermediate hazard class, where AMD process could occur only if certain conditions are met. Finally, the persistence of the AMD process in the Rio Marina area was evaluated on the basis of yearly rainfall, mining waters pH and NAPP values. A complete leaching of the first 0.25 m of the earth materials can retain the current environmental conditions for several centuries.  相似文献   

13.
The comparative behaviour of Ni, Cu and Zn in the system “mine tailings–ground water–plants” has been investigated at the Ni–Cu mine site operated by INCO Ltd. Thompson Operations, Thompson, Manitoba. Oxidation of sulphide minerals causes the release of metals from exposed tailings containing Ni ∼2000 ppm, Cu ∼150 ppm and Zn ∼100 ppm to the ground water, which contains 350 mg/L Ni, 0.007 mg/L Cu, and 1.6 mg/L Zn. The metal concentration in the ground water is affected by the relative proportions of sulfide minerals, the rate of oxidation of sulphide minerals (Ni-bearing pyrrhotite > sphalerite > chalcopyrite), and the affinity of the metals for secondary Fe-phases (Ni > Zn > Cu).  相似文献   

14.
《Applied Geochemistry》2006,21(2):377-403
Predictions of mine-related water pollution are often based on laboratory assays of mine-site material. However, many of the factors that control the rate of element release from a site, such as pH, water–rock ratio, the presence of secondary minerals, particle size, and the relative roles of surface-kinetic and mineral equilibria processes can exhibit considerable variation between small-scale laboratory experiments and large-scale field sites.Monthly monitoring of mine effluent and analysis of natural geological material from four very different mine sites have been used to determine the factors that control the rate of element release and mineral sources and sinks for major elements and for the contaminant metals Zn, Pb, and Cu. The sites are: a coal spoil tip; a limestone-hosted Pb mine, abandoned for the last 200 a; a coal mine; and a slate-hosted Cu mine that was abandoned 150 a ago. Hydrogeological analysis of these sites has been performed to allow field fluxes of elements suitable for comparison with laboratory results to be calculated. Hydrogeological and mineral equilibrium control of element fluxes are common at the field sites, far more so than in laboratory studies. This is attributed to long residence times and low water–rock ratios at the field sites. The high water storativity at many mine sites, and the formation of soluble secondary minerals that can efficiently adsorb metals onto their surfaces provides a large potential source of pollution. This can be released rapidly if conditions change significantly, as in, for example, the case of flooding or disturbance.  相似文献   

15.
黄铁矿风化过程中元素的活性及对环境的影响   总被引：7，自引：0，他引：7       下载免费PDF全文
卢龙  王汝成  薛纪越  陈骏 《地质论评》2001,47(1):95-101
在对安徽铜陵鸡冠山硫铁矿尾矿中黄铁矿风化产物组构特征研究的基础上,划分出代表不同风化程度的4种矿石组构型,并进而对不同组构型中硫和金属元素的含量、宫集系数、流失系数变化进行了研究。研究表明在风化过程中,As、Sb、Cu、Zn明显富集,其中As、Cu、Zn对环境的潜在危害较Sb大;Co、Ni、Bi明显流失或严重流失,对环境已经形成污染,其中Bi的污染程度较高。  相似文献   

16.
This study determines extractable levels of Cd, Cu, Pb, Zn, Ni and Co in western Almería (Spain) greenhouse surface soil horizons using EDTA solution, which is identified as the fraction available for organisms and plants. It also establishes background levels, geochemical baseline concentration and reference values (RV), and investigates the possible relationships between soil properties and elemental concentrations. The results show that the soil concentration of these extractable heavy metals was high as those reported by other authors for Spanish agricultural soils. The available RV concentrations obtained (mg kg−1) were: Cd 0.17, Cu 1.6, Pb 13.8, Zn 5.0 Ni 1.7 and Co 2.9. Using the upper baseline criterion, 95% of greenhouse soils present a relatively higher content of extractable heavy metals given their Cd and Cu concentration. Significant correlations between total and EDTA-extractable metal levels were found for Zn, Pb, Cu, Cd and Ni. Soil properties also related to heavy metals content, suggesting that Cd, Cu, Pb and Zn are of similar origin and relate to anthropic activities, and implies the same interactions and/or relationships among these metals.  相似文献   

17.
Levels of the chalcophile metals Hg, Pb, Cd, Cu and Zn and the metalloid As in soils from rice paddy fields were assessed in two regions impacted by different industrial activities in Guizhou province, China. The two study areas (Wanshan and Qingzhen) have previously received attention in the international literature due to heavy Hg pollution, though levels of other potentially harmful elements have not previously been reported. The regions were selected as representing two important, but categorically different metal(loid) contaminated areas in China: Wanshan has been a major region for Hg production while Qingzhen is an important region for a large range of various heavy industries based on coal as an energy source.Within a limited distance of the Hg mine tailings in Wanshan the rice paddy fields are heavily contaminated by Hg (median concentration 25 μg g−1, maximum 119 μg g−1) and moderately contaminated by Zn and Cd (median concentrations of 86 and 0.9 μg g−1, respectively). Zinc and Cd levels correlate well with Hg contamination, which indicates a similar source and mechanism of transport and accumulation. Other studies have concluded that the main sources of Hg contamination in Wanshan are the numerous Hg mine tailings. This is likely as these metals are all geochemically associated with the mineral cinnabar (HgS). The other chalcophile elements (Pb, Cu and As) are nevertheless found at background levels only. In Qingzhen the soils were found to contain elevated levels of As and Hg (median concentrations of 38 and 0.3 μg g−1, respectively). These are elements that are known to be more associated with coal and released during coal combustion.  相似文献   

18.
《Applied Geochemistry》1997,12(3):243-254
Column flow-through experiments reacting wastewater solutions with sandy loam soil samples were performed to study heavy metal attenuation by two soils with different physical and chemical properties. Reacted soil columns were leached with synthetic acid rain to study the mobility of attenuated heavy metals under leaching conditions. This study demonstrates that cation exchange, surface adsorption, chelation with solid organic material, and precipitation were the important attenuation mechanisms for the heavy metals (Cd, Cr, Cu, Mo, Ph, and Zn). Adsorption on soil hydrous oxide surfaces was the primary attenuation mechanism for Cd and Zn in both soils, and for Cu in a soil with low organic matter content. Wastewater solution pH is also an important factor that influences the retention of heavy metals. Cadmium, Cu, Cr, and Zn became mobile after prolonged application of spiked wastewater solution, either through saturation of soil adsorption sites or due to decreasing pH. Only Cr, Pb, and Mo, which are attenuated primarily through precipitation, show significant net retention by soil. Acid rain water removed heavy metals left in the column residual pore solution and weakly sorbed heavy metals in the soils, and has the ability to mobilize some strongly attenuated heavy metals, especially when the soil organic matter content is high. The results have important applications in predicting heavy metal mobility in contaminated soil, the disposal of acid mine drainage, and assessing the risks of landfall leachate leakage.  相似文献   

19.
In the mining district of Plombières-La Calamine (East Belgium), extensive Pb–Zn mining activities resulted in an important contamination of overbank sediments along the Geul river. Moreover, a huge amount of heavy metals is stored in a dredged mine pond tailing, which is located along the river. In the dredged mine pond tailing sediments, Pb–Zn minerals control the solubility of Zn, Pb and Cd. Although Pb, Zn and Cd display a lower solubility in overbank sediments compared to the mine tailing pond sediments, elevated concentrations of Pb, Zn and Cd are still found in the porewater of the overbank sediments. The considerable ‘actual’ and ‘potential’ mobility of Zn, Pb and Cd indicates that the mine pond tailing sediments and the overbank sediments downstream from the mine pond tailing represent a considerable threat for the environment. Besides the chemical remobilisation of metals from the sediments, the erosion of overbank sediments and the reworking of riverbed sediments act as a secondary source of pollution.  相似文献   

20.
A study was initiated to analyse metal flows from alum shale to the environment in an area in Öland, Sweden. The study was performed by elemental analysis and leaching experiments of alum shale together with analysis of groundwater and surface water samples.The metal concentrations in non-weathered alum shale were much higher than in weathered or burnt shale, especially for cadmium (Cd), nickel (Ni) and zinc (Zn), indicating a loss of metals during weathering or burning of the shale. The release of metals through weathering was clearly demonstrated by the leaching tests. A 36-week leaching period of non-weathered shale resulted in a drastic drop in pH and a significant increase in metal concentrations in the leachate. The metal concentrations in groundwater were inversely related to the pH. For surface waters, the concentrations of Cd, copper (Cu), Ni and Zn were generally increased compared to background values.In conclusion, metals are released through weathering or burning of alum shale, as well as from heaps of weathered or burnt shale. The release of metals is strongly related to low pH, especially for Cd, Ni and Zn.  相似文献   

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