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1.
A primary lead smelter operating in Santo Amaro, Bahia, Brazil, from 1960 to 1993 generated a large amount of slag that was landfilled close to the former smelter and used in roads and houses as a construction material. To evaluate the stability of the slag classical leaching procedures (TCLP, SWEP and SPLP) were applied. In addition, samples of the slag were placed in contact with HCl, HNO3, HOAc and NaOH solutions for about 24 h at room temperature to simulate acidic and alkaline environments over a wide pH range. In the acidic environment Ca, Fe and Si are strongly solubilized, and Pb and Zn solubilization was significant only below pH 3. The lead slag was also in contact with purified water for a period of 30 days. The results show that Ca and Si were solubilized and Pb, Fe, and Zn were not detected in the solution. The solubilization kinetics are second order processes for both Ca and Si. The initial solubilization rate for Ca and Si are 4.6 and 0.6 mg/L/day, respectively. The main implication of these results is that the major potentially toxic elements of the lead slag landfilled at Santo Amaro were stabilized for a short contact time with pure water and for alkaline and acidic solutions to a pH of about 3 and the groundwater and the surface water contamination found at Santo Amaro smelter region cannot be directly attributed to the landfilled lead slag.  相似文献   

2.
Lead metallurgical slags are partially vitrified materials containing residual amounts of Zn, Pb, Cr, Cd and As. These hazardous materials are generally buried on heaps exposed to weathering. In this study, leaching behavior of lead blast furnace slags has been tested using pure water and open flow experiments. It appears that in such far from equilibrium and slightly acidic conditions, the main phase to be altered is the vitreous phase. As for lunar, basaltic and nuclear glasses, alkalis/proton exchanges prevail and lead to the formation of a non-protective altered layer enriched in Si, Fe and Al. The composition of the altered layer is quite constant except for Si whose concentration decreases towards the leachate interface. Owing to their sizes, micrometric Pb droplets are not always totally dissolved at the slag surface. Nevertheless, nanometric Pb droplets are instantaneously dissolved while a surrounding altered layer is formed. This leads to high Pb releases in open flow systems. Leachate chemistry and dissolution rates of the vitreous phase are closely comparable to previous leaching tests with basaltic and nuclear glasses in conditions far from equilibrium. Moreover, this study confirms that Fe is a stable element in such conditions.  相似文献   

3.
The leaching behaviour of fly ash from a Co smelter situated in the Zambian Copperbelt was studied as a function of pH (5–12) using the pH-static leaching test (CEN/TS 14997). Various experimental time intervals (48 h and 168 h) were evaluated. The leaching results were combined with the ORCHESTRA modelling framework and a detailed mineralogical investigation was performed on the original FA and leached solid residues. The largest amounts of Co, Cu, Pb and Zn were leached at pH 5, generally with the lowest concentrations between pH 9 and 11 and slightly increased concentrations at pH 12. For most elements, the released concentrations were very similar after 48 h and 168 h, indicating near-equilibrium conditions in the system. Calcite, clinopyroxenes, quartz and amorphous phases predominated in the fly ash. Various metallic sulfides, alloys and the presence of Cu, Co and Zn in silicates and glass were detected using SEM/EDS and/or TEM/EDS. The leaching of metals was mainly attributed to the dissolution of metallic particles. Partial dissolution of silicate and glass fractions was assumed to significantly influence the release of Ca, Mg, Fe, K, Al and Si as well as Cu, Co and Zn. The formation of illite was suggested by the ORCHESTRA modelling to be one of the main solubility-controlling phases for major elements, whereas Co and Zn were controlled by CoO and zincite, respectively. Sorption of metals on hydrous ferric oxides was assumed to be an important attenuation mechanism, especially for the release of Pb and Cu. However, there is a high risk of Co, Cu, Pb and Zn mobility in the acidic soils around the smelter facility. Therefore, potential local options for “stabilisation” of the fly ash were evaluated on the basis of the modelling results using the PHREEQC code.  相似文献   

4.
42 soil samples, chosen from 4 transects around brickworks in the Göttingen area (W. Germany), were examined for the toxic elements Bi, Tl, Cd, Pb, and Zn, as well as Fe, Mn, and organic carbon. In 44 plant samples (grass) taken from the same sites the trace elements Cd, Pb, and Zn and the matrix elements K, Ca, Mg, and Na, were determined. Around brickworks, which are situated in an unfavorable morphological region, small anomalies could be detected. A comparison with a highly polluted area around a lead-zinc smelter shows the relatively low level of pollution of the Göttingen area. By investigating 3 different sets of clay and bricks, the loss of some volatile heavy metals in the process of converting clay to brick could be estimated; the losses are between 17 and 83 percent. Extrapolating this to the entire German Federal Republic, Cd, Tl, Bi, and Hg are emitted in the 10–30 (tons per year) range, Pb and Zn in the 500–100 t/y range. The contamination of the environment by these metals from brickworks is about equal to that released by the coal as it is burned.  相似文献   

5.
The primary phases and minerals of the Plombières dumps include typical smelting furnace products such as metallic Fe, Pb, Cu, Zn, Fe-Zn alloys, carbides, phosphides, sulfides of Fe, Zn, Pb, Cu, Mn (alabandite), and FeAs. Spinels, mainly of Fe and Al, are common constituents of the primary assemblage; substitution by Zn, V, Cr, Ti, Mg, and Ca occurs. Primary phases also include the most common Zn-rich fayalite, Zn-rich Ca-Fe silicates, melilite, corundum, and apatite. Most of the Zn is incorporated in iron silicates, ZnO and ZnS. Lead occurs mainly as PbS, metallic lead, and is also present in coal residues. Cadmium is found mainly in metallic zinc and its alloys and in ZnO. The dumps also contain mining wastes composed of pyrite, melnikovite, and iron oxides produced by natural weathering of Zn-Pb ores. Melnikovite and iron oxides are rich in As, Pb, and Zn and possess an increased content of Tl. Leaching tests carried out on the surfaces of polished sections indicate that acid rain (solutions I and II) will mobilize mainly Zn and Cd and, to a much smaller extent, Pb and Sb. Leaching of metals by sulfate-chloride fluids present in the pore network of dumps (solutions III, IV, and V) depends on the pH, which in the dumps is controlled by the proportion of carbonates to sulfides. The more acid fluids leach both sulfides and silicates.  相似文献   

6.
Eighteen suspended sediment samples were collected along the Huanghe River main stem from upper reaches on the Qinghai-Tibet Plateau (Tibet Plateau) to the entrance at the Bo Hai Bay and at confluences of its tributaries, during the first summer flood in 1980. Major elements such as Si, Al, Fe, Ca, Mg, K, Na, and trace elements such as As, Ba, Cd, Ce, Co, Cr, Cu, Ga, Hg, Li, Mn, Mo, Ni, P, Pb, Se, Sn, Sr, Ti, V, Zn and humus were examined. Variations in composition of suspended sediments also were studied. Three major types of sediment composition were observed. The controlling factor for the variation is parent rocks, though climate and vegetation played an active role. Correlation coefficients, cluster analysis, and enrichment factors were calculated to study the geochemical characteristics of the sediments. Mg, Na and Fe were the only ones subject to considerable leaching, whereas Se, Cd, Zn were significantly accumulated, indicating a low intensity of weathering.  相似文献   

7.
Distribution of Tl, Zn, Cd, Pb, K, Ca, Mg and Mn and Pb isotopic composition in tree rings of Scots pine (Pinus sylvestris L.) from an area affected by primary Zn smelting (Olkusz, southern Poland) were investigated. Elevated concentrations of Tl (up to 0.8 mg kg−1) in pine trees imply that conifers tend to accumulate this metal to some extent. A generally positive relationship between soil and tree-ring Tl levels was identified. The Tl patterns in stem wood did not correspond to changes in Tl deposition; the lateral translocation of Tl in the sapwood and its accumulation at the sapwood-heartwood boundary (i.e., in the inner sapwood) is suggested. It is probable that the specific behavior of Tl in trees results from its biogeochemical analogy with K. In contrast, tree-ring patterns of Zn and Cd significantly correlated with their deposition; nevertheless, a partial shift of these metals towards the stem center cannot be excluded. The isotopic composition of Pb (206Pb/207Pb ~ 1.172–1.184) in trees and underlying soils revealed the predominant influence of smelter emissions (206Pb/207Pb ~ 1.17) on Pb contamination. Analysis of main nutrients (Ca, Mg and Mn) in wood reflected environmental changes related to acid deposition.  相似文献   

8.
恬矿库周围土壤中重金属存在形态特征研究   总被引：48，自引：4，他引：44  
通过对大冶铜绿山铜铁矿尾矿库周围土壤中重金属形态分析实验,研究了重金属各种形态在土壤中的分布特征。由对比实验可知,尾矿库周围土壤中Ｃｕ、Ｐｂ、Ｚｎ、Ｃｄ等重金属含量都显著地高于对照样品,书经受到重金属的严重污染。土壤中重金属形态分布征为：ｗ（Ｃｒ、Ｚｎ、Ｆｅ）;可变换态〈碳酸盐态〈有机态〈铁锰氧化态〈残渣态;ｗ（Ｃｕ、Ｐｂ）：可变换态〈碳酸盐态〈有机态〈残渣态〈铁锰氧化态;ｗ（Ｃｄ）：残渣态,有机  相似文献   

9.
The concentration and areal distribution of selected metals (Pb, Zn, Cu, Cd, Ni, Fe, and Cr) in the sediments of the Calabar River were studied to determine the extent of anthropogenic input and to estimate the effects of dumping industrial waste materials into the river. The concentrations of Pb, Zn, and Cu indicate relatively moderate pollution mainly on the left-hand side of the river while Ni, Cr, Co, Cd, and Fe levels are below values found to have adverse effects on the lives of marine biota. High metal contents are found close to industrial establishments and so enhanced metal concentrations are related to industrial sewage and metal leaching from garbage and solid waste dumps.  相似文献   

10.
Microscopic morphology and elemental composition of atmospheric particulate matter (PM) in 13 different size fractions from 0.01 to 10 μm were studied using a Field Emission Scanning Electron Microscope with Energy-Dispersive Spectrometer (FESEM–EDX). The relative mass fractions exhibited a bimodal distribution with a major mode in the fine range (0.18–1 μm) and a minor mode in the coarse range (>1 μm), suggesting that the major pollution of PM is fine particles in this area of Urumqi atmosphere. The PM could be classified as follows: aluminosilicate/silica mineral, Si–Al rich fly ash, Fe oxide particle, Ti dominant particle, sulfate/carbonate crystal, carbonaceous aerosols (including soot, organic carbon, tar ball and irregularly shaped carbon). The soot and organic carbon with anthropogenic sources are dominant types in fine range samples (<1 μm). The natural source minerals and secondary synthesized sulfate/carbonate crystals were accumulated in the coarse range (>1 μm). Elemental composition of various types of particles (0.056–5.6 μm) was also analyzed by EDX. C, S, O, N, Si, Al, Fe, Ca, Na, K, Mg, Cl, F, Hg were detected in most samples. Si, Al and Ca accumulated in coarse fractions, while S and Hg mainly accumulated in fine fractions. Concentrations of 15 metallic elements in size range from 0.1 μm to 5.6 μm were divided into three groups based on their possible sources. (1) The crustal elements (Al, Mg, Fe, Mn and V), mainly present in coarse particles (>1 μm); and (2) the anthropogenic source elements (Ca, Ni, As, Cu, Pb, Cd and Hg). The concentrations of Ca and Ni increased with increasing particle size, while As, Cu, Pb, Cd and Hg showed opposite trends. As, Cu, Pb, Cd and Hg accumulated mainly in fine fraction (<1 μm). (3) The multi sources elements (Cr, Co and Se) possibly come from both natural and anthropogenic sources. High levels of heavy metals, especially Hg in nanosize particles, may pose great risk to human health.  相似文献   

11.
Major (Al, Ca, Fe, Mg, Mn, Si) and minor (Cd, Pb, Zn) elements of aeolian dust samples collected onboard ship around Italy were analysed, and the concentrations of metal in the dusts were in good agreement with previously published data from the Mediterranean Sea.
The elemental composition of dust samples collected in four subareas (Adriatic, Ionian, Tyrrhenian, and Sicily Channel) was compared with the composition of marine deep sediments obtained in the same regions: Mn, Al, Cd and Zn contents differentiated between the four areas in both sets of samples, suggesting a possible 'geochemical signature' of the atmospheric crustal contribution in marine deep sediments.
An estimate of the relative contribution of atmospheric dry deposition of Cd, Pb and Zn and riverine discharge indicates that: (a) the metals deposited from the atmosphere to the Adriatic basin are a small fraction (2–5%) of those discharged by the Po and Adige rivers; (b) almost the same amounts of Cd, Pb and Zn are delivered to the Tyrrhenian Sea by the atmosphere and by the Arno and Tiber Rivers.  相似文献   

12.
The Gulf of Mannar along the Tuticorin coast is a coral base of the southeast coast of India. To obtain a preliminary view of its environmental conditions, geochemical distribution of major elements (Si, Al, Fe, Ca, Mg, Na, K, P), trace elements (Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) and acid leachable elements (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) were analyzed in surface sediment samples from two seasons. Geochemical fractionation confirmed the lithogenic origin of metals, which were mainly associated with the detrital phase. The sediments in the gulf are sandy with abundant calcareous debris, which controls the distribution of total and acid leachable elements. Enrichment factors relative to crust vary by a magnitude of two to three and the presence of trace metals indicates the input of Cr, Pb, Cd, Cu and Zn in both forms through industrial activities. Factor analysis supports the above observation with higher loadings on acid leachable elements and its association with CaCO3. The increase in concentration of trace metals (Cr, Pb, Cd, Cu, Co, Ni, Zn) along the Gulf of Mannar indicates that the area has been contaminated by the input from riverine sources and the industries nearby. The present study indicates that other sources should be evaluated in the long-term monitoring program.  相似文献   

13.
针对煤矸石山在降水淋滤作用下对矿区周边地下水造成污染的严重问题,用实验模拟法对包头石拐区一废弃煤矿进行饱和状态下煤矸石的淋滤实验研究。结果表明:煤矸石中Ca、Mg、Fe、Cu、Zn、NO3-、SO42-、Cl-的淋滤过程都遵循浓度先升高再降低到稳定值的基本规律,只是NO3-、SO42-、Cl-的淋出速率明显大于重金属的淋出速率,Ca和Mg、SO42-和Cl-、Pb和Cr、Cd有相似的淋出机制;重金属最强淋出率从大到小的顺序是Mg>Cd>Ca>Cu>Zn>Cr>Fe>Pb;Hg和As等含量甚微,均未检出。   相似文献   

14.
The results of investigations (SEM/EDS and AAS) of a peat deposit, spanning 13,000 years of peat accumulation, are shown. The peat deposit is located in a region of shallow occurrence of Zn–Pb ores, near Tarnowskie Góry town, within the Cracow–Silesia district (southern Poland). Exploitation of lead, silver and iron during the medieval times (Twelfth and thirteenth century) was confirmed by historical documents whereas there are no unambiguous data showing that there was metal mining during the Romanian or earlier times in the region. The peat deposit is located within the influence of atmospheric Pb and Zn emission from a nearby Zn–Pb smelter. Two vertical peat profiles were investigated (120 and 140 cm depth of profile) showing variable concentrations of Zn up to 713 mg kg?1, Pb up to 317 mg kg?1, Cd up to 13 mg kg?1 and Tl up to 31 mg kg?1. The highest concentrations were recorded for the uppermost peat layers. SEM and EDS investigations revealed the occurrence of metalbearing, submicroscopic mineral components: Fe, Mn, Ti and Zn oxides and Zn and Pb carbonates. The top layer of the deposit contained Zn, Pb and Cd sulphides. The occurrence of aggregates of Au–Ag, Cu–Zn and Au–Ag–Cu alloys can be possibly related to pre-historical mining and smelting or be explained by geochemical transformations. The preservation of carbonates and oxides in the peat is discussed, indicating a generally neutral to alkaline peat water chemistry and maintenance of an oxidized environment in the fen.  相似文献   

15.
Surface slices of 20 sediment cores, off southwestern Taiwan, and bed sediment of River Kaoping were measured for major and trace elements (Al, As, Ca, Cd, Cl, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Si, Ti, V, and Zn) to evaluate the geochemical processes responsible for their distribution, including elemental contamination. Major element/Al ratio and mean grain size indicate quartz-dominated, coarse grained sediments that likely derived from sedimentary rocks of Taiwan and upper crust of Yangtze Craton. Bi-plot of SiO2 versus Fe2O3T suggests the possible iron enrichment in sediments of slag dumping sites. Highest concentrations of Cr, Mn, P, S, and Zn found in sediments of dumping sites support this. Correlation analysis shows dual associations, detrital and organic carbon, for Cr, P, S, and V with the latter association typical for sediments in dumping sites. Normalization of trace elements to Al indicates high enrichment factors (>2) for As, Cd, Pb, and Zn, revealing contamination. Factor analysis extracted four geochemical associations with the principal factor accounted for 25.1% of the total variance and identifies the combined effects of dumped iron and steel slag-induced C–S–Fe relationship owing to authigenic precipitation of Fe–Mn oxyhydroxides and/or metal sulfides, and organic matter complexation of Fe, Mn, Ca, Cr, P, and V. Factors 2, 3, and 4 reveal detrital association (Ti, Al, Ni, Pb, Cu, and V), effect of sea salt (Cl, Mg, Na, and K) and anthropogenic component (As and Zn)-carbonate link, respectively, in the investigated sediments.  相似文献   

16.
首钢地区表层土壤重金属的分布特征及污染评价   总被引：2，自引：0，他引：2  
韩鹏  孙天河  袁国礼  黄勇 《现代地质》2012,26(5):963-971
利用多元统计分析和空间分析相结合的方法,分析了首钢地区表层土壤中Fe、Cr、Ni、V、As、Cd、Pb、Cu、Zn、Hg 10种重金属元素的地球化学特征。研究结果表明,10种元素可以归结为4类:第一类Ni、V、As的含量低于自然背景值,主要受成土母质等自然因素的影响;第二类Cd、Cu、Pb、Zn的含量已经超出自然背景值,其中Cu、Pb、Zn属于轻度污染,Cd属于中度污染,这一类元素主要受到交通和冶炼等人为因素的影响,高值区主要分布于居民区;第三类为Fe、Cr,同时受到自然因素和人为因素的共同影响,高值区集中分布在厂区和部分居民区;第四类为Hg,Hg因其是一种非点源污染的元素而单独聚为一类,主要受到人为因素的影响且高值样点位于河流区。总体而言,首钢地区表层土壤已经受到部分污染,需密切关注其对环境的危害及人群的潜在健康风险。本研究对该区域土壤污染风险评价和土地利用规划等具有一定的借鉴意义。  相似文献   

17.
Three types of smelting slags originating from historically different smelting technologies in the Tsumeb area (Namibia) were studied: (i) slags from processing of carbonate/oxide ore in a Cu–Pb smelter (1907–1948), (ii) slags from Cu and Pb smelting of sulphide ores (1963–1970) and (iii) granulated Cu smelting slags (1980–2000). Bulk chemical analyses of slags were combined with detailed mineralogical investigation using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM/EDS) and electron microprobe (EPMA). The slags are significantly enriched in metals and metalloids: Pb (0.97–18.4 wt.%), Cu (0.49–12.2 wt.%), Zn (2.82–12.09 wt.%), Cd (12–6940 mg/kg), As (930–75,870 mg/kg) and Sb (67–2175 mg/kg). Slags from the oldest technology are composed of primary Ca- and Pb-bearing feldspars, spinels, complex Cu–Fe and Cu–Cr oxides, delafossite–mcconnellite phases and Ca–Pb arsenates. The presence of arsenates indicates that these slags underwent long-term alteration. More recent slags are composed of high-temperature phases: Ca–Fe alumosilicates (olivine, melilite), Pb- and Zn-rich glass, spinel oxides and small sulphide/metallic inclusions embedded in glass. XRD and SEM/EDS were used to study secondary alteration products developed on the surface of slags exposed for decades to weathering on the dumps. Highly soluble complex Cu–Pb–(Ca) arsenates (bayldonite, lammerite, olivenite, lavendulan) associated with litharge and hydrocerussite were detected. To determine the mineralogical and geochemical parameters governing the release of inorganic contaminants from slags, two standardized short-term batch leaching tests (European norm EN 12457 and USEPA TCLP), coupled with speciation-solubility modelling using PHREEQC-2 were performed. Arsenic in the leachate exceeded the EU regulatory limit for hazardous waste materials (2.5 mg/L). The toxicity limits defined by USEPA for the TCLP test were exceeded for Cd, Pb and As. The PHREEQC-2 calculation predicted that complex arsenates are the most important solubility controls for metals and metalloids. Furthermore, these phases can readily dissolve during the rainy season (October to March) and flush significant amounts of As, Pb and Cu into the environment in the vicinity of slag dumps.  相似文献   

18.
长江中下游地区地下水中化学元素的背景特征及形成   总被引：46，自引：0，他引：46  
曾昭华 《地质学报》1996,70(3):262-269
本文论证了长江中下游地区地下水中钾、钠、钙、镁、硅、铁、锰、铬、镍、钒、钴、钛、钼、铜、铅、锌、砷、汞、镉、铍、锂、锶、硼、氟、氯、溴、碘的背景特征、形成及分布规律,探讨其与地下水的含水介质成分,上覆岩土性质、氧化还原环境、地下水的径流条件和矿化度以及地下水的酸碱度之间的关系。  相似文献   

19.
《Applied Geochemistry》2004,19(7):1039-1064
Slag collected from smelter sites associated with historic base-metal mines contains elevated concentrations of trace elements such as Cu, Zn and Pb. Weathering of slag piles, many of which were deposited along stream banks, potentially may release these trace elements into the environment. Slags were sampled from the Ely and Elizabeth mines in the Vermont copper belt, from the copper Basin mining district at Ducktown, Tennessee and from the Clayton silver mine in the Bayhorse mining district, Idaho, in the USA. Primary phases in the slags include: olivine-group minerals, glass, spinels, sulfide minerals and native metals for Vermont samples; glass, sulfide minerals and native metals for the Ducktown sample; and olivine-group minerals, clinopyroxenes, spinels, sulfide minerals, native metals and other unidentified metallic compounds for Clayton slag. Olivine-group minerals and pyroxenes are dominantly fayalitic and hedenbergitic in composition, respectively and contain up to 1.25 wt.% ZnO. Spinel minerals range between magnetite and hercynite in composition and contain Zn (up to 2.07 wt.% ZnO), Ti (up to 4.25 wt.% TiO2) and Cr (up to 1.39 wt.% Cr2O3). Cobalt, Ni, Cu, As, Ag, Sb and Pb occur in the glass phase, sulfides, metallic phases and unidentified metallic compounds. Bulk slag trace-element chemistry shows that the metals of the Vermont and Tennessee slags are dominated by Cu (1900–13,500 mg/kg) and Zn (2310–10,200 mg/kg), whereas the Clayton slag is dominated by Pb (63,000 mg/kg), Zn (19,700 mg/kg), Cu (7550 mg/kg), As (555 mg/kg), Sn (363 mg/kg) and Ag (200 mg/kg). Laboratory-based leach tests indicate metals can be released under simulated natural conditions. Leachates from most slags were found to contain elevated concentrations of Cu and Zn (up to 1800 and 470 μg/l, respectively), well in excess of the acute toxicity guidelines for aquatic life. For the Idaho slag, the concentration of Pb in the leachate (11,000 μg/l) is also in excess of the acute toxicity guideline. Geochemical modeling of the leachate chemistry suggests that leachates from the Vermont, Tennessee and Clayton slags are saturated with amorphous silica and Al hydroxide. Therefore, the dissolution of silicate and oxide phases, the oxidation of sulfide phases, as well as the precipitation of secondary phases may control the composition of leachate from slags. The presence of secondary minerals on slag deposits in the field is evidence that these materials are reactive. The petrographic data and results of leaching tests from this study indicate slag may be a source of potentially toxic metals at abandoned mine sites.  相似文献   

20.
 Trace element geochemistry of humus (<0.425 mm) and till (<0.002 mm) collected in the Flin Flon-Snow Lake area, northern Manitoba and Saskatchewan, provides a regional context for assessing smelter contamination in the environment. The area includes a Cu-Zn smelter known to discharge As, Cd, Cu, Fe, Hg, Pb, and Zn. In this study, sequential extraction analyses, scanning electron microscopy and x-ray diffraction analyses were used on a suite of samples to determine: (1) the chemical and physical characteristics of heavy metals in surficial sediments related to distance from the smelter, (2) criteria for assessing the relative contribution of these metals from natural and anthropogenic sources, and (3) the potential of these metals for remobilization in the environment. Humus geochemistry reflects the anthropogenic and natural component of heavy metal concentrations. Smelter-related elements show anomalously high values adjacent to the smelter, decreasing with distance until background values are reached at 70–104 km, depending on the element. In humus, Zn is associated primarily with labile phases; Hg with non-labile phases. Adjacent to the smelter, high proportions and concentrations of Zn and Hg in non-labile phases, indicative of smelter-derived particulates, are confirmed by SEM examination. The particles occur as spheres, irregular grains, and with organics. With increasing distance from the smelter, the geochemical response to bedrock composition is more obvious than the anthropogenic input. Till geochemistry reflects the natural variation imposed by bedrock composition. At highly contaminated sites (<3 km from the smelter), increased percentages of smelter-related elements in labile phases suggests heavy metals are leached from humus to the underlying sediment. Received: 5 November 1996 · Accepted: 31 March 1997  相似文献   

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