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1.
The Mike Horse Mine tailings dam in western Montana was partially breached in 1975 due to heavy rainfall and a failed drainage bypass. Approximately 90,000 tons of metal and arsenic-enriched tailings flowed into Beartrap Creek and the Blackfoot River. The spatial distribution of trace elements As, Cd, Cu, Mn, Pb, and Zn in floodplain alluvium of the upper Blackfoot River were examined along 20 transects in the upper 105 river kilometers downstream from the tailings dam. Trace element concentrations decrease with distance from the failed dam, with As reaching background concentrations 15 km from the Mike Horse dam, Cd and Pb at 21 km, Cu at 31 km, and Mn and Zn at 37 km. Distance from the Mike Horse tailings dam and mine area is the dominating factor in explaining trace element levels, with R 2 values ranging from 0.67 to 0.89. Maximum floodplain trace element concentrations in the upper basin exceed US. EPA ecological screening levels for plants, birds and other mammals, and reflect adverse hazard quotients for exposure to As and Mn for ATV/motorcycle use. Trace element concentrations in channel bank and bed alluvium are similar to concentrations in floodplain alluvium, indicating active transport of trace elements through the river and deposition on the floodplain. The fine fraction (<2 mm) of floodplain alluvium is dominated by sand-sized particles (2.0–0.05 mm), with Cu and Mn significantly correlated with silt-sized (0.05–0.002 mm) alluvium. Ongoing remediation in the headwaters area will not address metal contamination stored downstream in the channel banks and on the floodplain. Additionally, some trace elements (Cu, Mn and Zn) were conveyed farther downstream than were others (As, Cd, Pb).  相似文献   

2.
《Applied Geochemistry》2000,15(5):655-666
A process model was used to better understand the controls on the chemical evolution of drainage in a historic mining district. At the Pecos Mine Operable Unit, New Mexico, drainage near the waste rock pile is acidic (pH varies from 3.0–5.0) and carries high concentrations of Zn, Al, Cu and Pb. As drainage flows toward the Pecos River, pH increases to greater than 7 and heavy metal content decreases. A process model of natural attenuation in this drainage shows the main controls on pH are reaction with a local bedrock that contains limestone, and concurrent mixing with tributary streams. Models that account for both calcite dissolution and mixing reproduce the observed decrease in aqueous metal concentrations with increasing pH. Contaminant concentrations attenuate primarily via two distinct pathways: Al, Cu, Fe and Pb precipitate directly from solution, whereas Zn, Mg, Mn and SO4 concentrations decrease primarily through dilution. Additionally, Pb adsorbs to precipitating hydroxide surfaces.  相似文献   

3.
The River Vişeu catchment in Maramureş County, northwestern Romania, has a long history of base and precious metal mining. Between 1994 and 2003 waste from mining activity at Baia Borşa was stored in the Novaţ-Roşu tailings pond in the upper Vişeu catchment. However, in March 2000, the tailings dam failed releasing approximately 100,000 m3 of contaminated water and 20,000 t of mineral-rich solid waste, which was routed downstream through the Rivers Novaţ, Vaser and Vişeu into the River Tisa. Following the accident metal (Cd, Cu, Pb, Zn) concentrations in river water and river channel sediment were assessed in samples collected annually (July 2000, 2001, 2002 and 2003) from 29 sites in the Vişeu catchment, downstream of the tailings pond. Additionally, the speciation of sediment-associated metals was established using a 4-stage sequential extraction procedure (SEP) and Pb isotope analysis (206/204Pb and 207/204Pb) was carried out to establish the provenance of contaminated sediments. Metal concentrations in river water were found to comply with EU directive ‘target’ values within four months of the failure. However, the impact of the spill upon river channel sediments was found to be much longer-lasting, with evidence of the delayed downstream remobilization of tailings stored within the narrow Novaţ valley following the dam failure, as well as continued inputs of contaminated sediment to the River Vişeu from the River Tisla, another mining-affected tributary. Comparison with data from other recent tailings dam failures, indicates that river system recovery rates depend upon local geomorphological conditions, hydrological regimes, and the nature and scale of post-spill clean-up operations.  相似文献   

4.
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   

5.
Small-scale mining and mineral processing at the Webbs Consols polymetallic PbZnAg deposit in northern New South Wales, Australia has caused a significant environmental impact on streams, soils and vegetation. Unconfined waste rock dumps and tailings dams are the source of the problems. The partly oxidised sulphidic mine wastes contain abundant sulphides (arsenopyrite, sphalerite, galena) and oxidation products (scorodite, anglesite, smectite, Fe-oxyhydroxides), and possess extreme As and Pb (wt% levels) and elevated Ag, Cd, Cu, Sb and Zn values. Contemporary sulphide oxidation, hardpan formation, crystallisation of mineral efflorescences and acid mine drainage generation occur within the waste repositories. Acid seepages (pH 1.9–6.0) from waste dumps, tailings dams and mine workings display extreme As, Pb and Zn and elevated Cd, Cu and Sb contents. Drainage from the area is by the strongly contaminated Webbs Consols Creek and although this stream joins and is diluted by the much larger Severn River, contamination of water and stream sediments in the latter is evident for 1–5 km, and 12 km respectively, downstream of the mine site. The pronounced contamination of local and regional soils and sediments, despite the relatively small scale of the former operation, is due to the high metal tenor of abandoned waste material and the scarcity of neutralising minerals. Any rehabilitation plan of the site should include the relocation of waste materials to higher ground and capping, with only partial neutralisation of the waste to pH 4–5 in order to limit potential dissolution of scorodite and mobilisation of As into seepages and stream waters.  相似文献   

6.
The San Pedro River (SPR) is located in northern Sonora (Mexico) and southeastern Arizona (USA). SPR is a transboundary river that develops along the Sonora (Mexico) and Arizona (USA) border, and is considered the main source of water for a variety of users (human settlements, agriculture, livestock, and industry). The SPR originates in the historic Cananea mining area, which hosts some of the most important copper mineralizations in Mexico. Acid mine drainage derived from mine tailings is currently reaching a tributary of the SPR near Cananea City, resulting in the contamination of the SPR with heavy metals and sulfates in water and sediments. This study documents the accumulation and distribution of heavy metals in surface water along a segment of the SPR from 1993 to 2005. Total concentrations of Cd, Cu, Fe, Mn, Pb, and Zn in surface waters are above maximum permissible levels in sampling sites near mine tailing deposits. Nevertheless, a significant decrease in the Fe and SO4 2− in surface water (SO4 2−: 7,180–460.39 mg/L; Fe: 1,600–9.51 mg/L) as well as a gradual decrease in the heavy and transition metal content were observed during the period from 1994 to 2005. Approximately 2.3 km downstream of the mine tailings, the heavy metal content of the water drops quickly following an increase in pH values due to the discharging of wastewater into the river. The attenuation of the heavy metal content in surface waters is related to stream sediment precipitation (accompanied by metal coprecipitation and sorption) and water dilution. Determining the heavy metal concentration led to the conclusion that the Cananea mining area and the San Pedro River are ecosystems that are impacted by the mining industry and by untreated wastewater discharges arising from the city of Cananea (Sonora, Mexico).  相似文献   

7.
Heavy metal concentrations in floodplain surface soils, Lahn River, Germany   总被引：2，自引：0，他引：2  
 Even relatively pristine drainage basins in industrial countries would appear to have received anthropogenic inputs of heavy metals. Investigation of floodplain surface soils in the Lahn River drainage basin, west-central Germany, indicates that the Cu concentration is 1.5 times the pre-industrial level, Pb and Zn contents twice the pre-industrial level; Cd, Co, and Cr concentrations are nearly equal to background metal values. Based on contamination standards developed for the Lahn River, floodplain soils are moderately contaminated with Pb and Zn, slightly contaminated with Cu. Metal contents are uniform across the floodplain, with the exception of a peak immediately adjacent to the Lahn River. Floodplain surface soil metal contents are less in the Lahn River basin than in larger drainage systems of Germany. Although Lahn River metalliferous sediments are presently immobile, they would, if eroded, contribute to downstream heavy metal concentrations. Consequently, metal storage in smaller drainage basins such as the Lahn should be considered in predictions of future metal loads in major river systems, for aggregate small basins could serve as significant metal contributors. Received: 21 August 1995 · Accepted: 23 January 1996  相似文献   

8.
《Applied Geochemistry》2003,18(2):241-257
In January and March 2000 two tailings dam failures in Maramureş County, northwest Romania, resulted in the release of 200,000 m3 of contaminated water and 40,000 tonnes of tailings into tributaries of the Tisa River, a major tributary of the Danube. The high concentrations of cyanide and contaminant metals released by these dam failures resulted in pollution and fish deaths not only in Romania, but also downstream in the Tisa and Danube rivers within Hungary, Serbia and Bulgaria. Following these accidents, a research programme was initiated in northwest Romania to establish metal levels in rivers affected by the tailings dam failures and to compare these to metal values in river systems contaminated by historic mining and industrial activity. In July 2000, 65 surface water, 65 river sediment and 45 floodplain sediment samples were collected from trunk streams and principal tributaries of the Lapuş/Someş rivers (affected by the January 2000 spill) and the Vişeu/Tisa rivers (affected by the March 2000 Novat spill) down to the Hungarian and Ukrainian borders, respectively. Sample analyses for Pb, Zn Cu and Cd show that metal contamination in surface water and river sediment decreases rapidly downstream away from presently active mines and tailings ponds. Concentrations of heavy metals in water and sediment leaving Romania, and entering Hungary and the Ukraine, generally fall below EC imperative and Dutch intervention values, respectively. However, Zn, Cu and Cd concentrations in river sediments approach or exceed intervention values at the Romanian border. The results of this survey are compared with earlier surveys to ascertain the long-term fate and environmental significance of contaminant metals released by mine tailings dam failures in Maramureş County.  相似文献   

9.
碳酸盐型尾矿在缓冲期/中性矿山废水(NMD)释放期的重金属污染问题易被忽视。本文以广西大厂锡石-硫化物尾矿作为研究对象,采用柱淋滤实验方法,探讨碳酸盐型尾矿在缓冲期重金属的释放机制,为此类型尾矿重金属污染的防治提供依据。实验结果表明,大厂尾矿在缓冲期(约7年,pH值为6. 6～8. 0)存在Sb、Zn、Cd、As(Pb)释放污染问题。在尾矿堆放初期(0. 5年,pH值由7. 6降至7. 2),Zn、Sb、Cd快速、大量释出;中期(0. 5～2. 5年,pH值由7. 2波动升高至8. 0),Sb较平稳释出;后期(2. 5～7年,pH值变化范围为8. 0～6. 6,呈降低趋势),受气温及pH值影响,As、Sb(Pb)呈波动或间歇振荡释出,即在夏季高温、pH值较高时,释出元素浓度较高,反之,在冬季低温、pH值较低时,释出元素浓度较低。重金属的释放与尾矿中硫化物的氧化程度高低及氧化先后顺序有关。这些矿物的氧化顺序大致为:闪锌矿(Zn、Cd)、辉锑锡铅矿(Sb)→脆硫锑铅矿(Sb)→毒砂(As)、方铅矿(Pb)。因此,对于(广西大厂)碳酸盐型尾矿在缓冲期的重金属污染应分阶段、季节(夏季),采取有针对性的防治措施;在缓冲期(7年)后应注意尾矿酸性矿山废水(AMD)+重金属(如As、Sb)复合污染的防治。  相似文献   

10.
The abandoned pyrite mine of São Domingos, in the southeast Portugal is still an acid mine drainage generator and a source for trace elements pollution. This study aims to evaluate and map the soils and sediments chemical pollution. With this purpose three test sites located in the vicinities of the mine were sampled for soils, sediments and mining waste materials. The samples were analysed for pH, organic carbon, iron oxides and total content of As, Cu, Cr, Hg, Pb, Sb, U, Zn, Mn, S, Fe Al, Ca, K, Mg and P. The hyperspectral image of the test sites was acquired using the aero transported sensor HymapTM. Chemical analysis and hyperspectral images data were processed to estimate the contamination maps by multivariate data analysis, ordinary kriging, cokriging and indicator kriging methodologies.The test sites located downstream the mine open pit, are highly contaminated mainly in As, Hg, Pb and Sb, but no contamination was found in the third test site, upstream the mining site. The acid mining drainage seems to be the main spreading agent of chemical contaminants mostly originating from the mine waste materials. Factorial analysis and the geostatistical methodologies allowed several approaches for the contamination cartography of mining areas.  相似文献   

11.
The Tinto and Odiel rivers drain 100 km from the Rio Tinto sulphide mining district, and join at a 20-km long estuary entering the Atlantic Ocean. A reconnaissance study of heavy metal anomalies in channel sand and overbank mud of the river and estuary by semi-quantitative emission dc-arc spectrographic analysis shows the following upstream to downstream ranges in ppm (μg g?1): As 3,000 to <200, Cd 30 to <0.1, Cu 1,500 to 10, Pb 2,000 to <10, Sb 3000 to <150, and Zn 3,000 to <200. Organic-rich (1.3–2.6% total organic carbon, TOC), sandysilty overbank clay has been analyzed to represent suspended load materials. The high content of heavy metals in the overbank clay throughout the river and estuary systems indicates the importance of suspended sediment transport for dispersing heavy metals from natural erosion and anthropogenic mining activities of the sulfide deposit. The organic-poor (0.21–0.37% TOC) river bed sand has been analyzed to represent bedload transport of naturally-occurring sulfide minerals. The sand has high concentrations of metals upstream but these decrease an order of magnitude in the lower estuary. Although heavy metal contamination of estuary mouth beach sand has been diluted to background levels estuary mud exhibits increased contamination apparently related to finer grain size, higher organic carbon content, precipitation of river-borne dissolved solids, and input of anthropogenic heavy metals from industrial sources. The contaminated estuary mud disperses to the inner shelf mud belt and offshore suspended sediment, which exhibit metal anomalies from natural erosion and mining of upstream Rio Tinto sulphide lode sources (Pb, Cu, Zn) and industrial activities within the estuary (Fe, Cr, Ti). Because heavy metal contamination of Tinto-Odiel river sediment reaches or exceeds the highest levels encountered in other river sediments of Spain and Europe, a detailed analysis of metals in water and suspended sediment throughout the system, and epidemiological analysis of heavy metal effects in humans is appropriate.  相似文献   

12.
The mining and processing of metal-bearing ores has resulted in contamination issues where waste materials from abandoned mines remain in piles of untreated and unconsolidated material, posing the potential for waterborne and airborne transport of toxic elements. This study presents a systematic method of particle size separation, mass distribution, and bulk chemical analysis for mine tailings and adjacent background soil samples from the Rand historic mining district, California, in order to assess particle size distribution and related trends in metal(loid) concentration as a function of particle size. Mine tailings produced through stamp milling and leaching processes were found to have both a narrower and finer particle size distribution than background samples, with significant fractions of particles available in a size range (?250 μm) that could be incidentally ingested. In both tailings and background samples, the majority of trace metal(loid)s display an inverse relationship between concentration and particle size, resulting in higher proportions of As, Cr, Cu, Pb and Zn in finer-sized fractions which are more susceptible to both water- and wind-borne transport as well as ingestion and/or inhalation. Established regulatory screening levels for such elements may, therefore, significantly underestimate potential exposure risk if relying solely on bulk sample concentrations to guide remediation decisions. Correlations in elemental concentration trends (such as between As and Fe) indicate relationships between elements that may be relevant to their chemical speciation.  相似文献   

13.
《Applied Geochemistry》2003,18(2):221-239
The Aznalcóllar tailings dam at Boliden Apirsa's Aznalcóllar/Los Frailes Ag–Cu–Pb–Zn mine 45 km west of Seville, Spain, was breached on 25 April 1998, flooding approximately 4600 hectares of land along the Rı́os Agrio and Guadiamar with approximately 5.5 million m3 of acidic water and 1.3×106 m3 of heavy metal-bearing tailings. Most of the deposited tailings and approximately 4.7×106 m3 of contaminated soils were removed to the Aznalcóllar open pit during clean-up work undertaken immediately after the spill until January 1999. Detailed geomorphological and geochemical surveys of the post-clean-up channel, floodplain and valley floor, and sediment and water sampling, were carried out in January and May 1999 at 6 reaches representative of the types of river channel and floodplain environments in the Rı́o Guadiamar catchment affected by the spill. The collected data show that the clean-up operations removed enough spill-deposited sediment to achieve pre-spill metal (Ag, As, Cd, Cu, Pb, Sb, Tl, Zn) concentrations in surface sediment. These concentrations, however, are still elevated above pre-mining concentrations, and emphasise that mining continues to contaminate the Agrio-Guadiamar river system. Dilution by relatively uncontaminated sediment appears to reduce metal concentrations downstream but increases in metal and As concentrations occur downstream, presumably as a result of factors such as sewage and agriculture. River water samples collected in May 1999 have significantly greater dissolved concentrations of metals and As than those from January 1999, probably due to greater sulphide oxidation from residual tailings with concomitant release of metals in the warmer early summer months. These concentrations are reduced downstream, probably by a combination of dilution and removal of metals by mineral precipitation. Single chemical extractions (de-ionised water, CaCl2 0.01 mol l−1, CH3COONH4 1 M, CH3COONa 1 M and ammonium oxalate 0.2 M) on alluvial samples from reaches 1 and 6, the tailings, pre-spill alluvium and marl have shown that the order of sediment-borne contaminant mobility is generally Zn>Cd>Cu>Pb>As. Pb and As are relatively immobile except possibly under reducing conditions. Much of the highly contaminated sediment remaining in the floodplain and channel still contains a large proportion of tailings-related sulphide minerals which are potentially reactive and may continue to release contaminants to the Agrio–Guadiamar river system. Our work emphasises the need for pre-mining geomorphological and geochemical data, and an assessment of potential contributions of contaminants to river systems from other, non-mining sources.  相似文献   

14.
Molybdenum mining in the Knabena—Kvina drainage basin (1918–1973) left more than eight million tons of tailings in two small lakes in the headwater area of the Knabena river. The piles, that reach above the water surface, were freely eroded until a dam was built to reduce the dispersion in 1976. Sampling of tailings and fluvial sediments took place almost 20 years later. Sampling media were natural sediment sources, 1-cm-thick slices of overbank sediments of various depths, material from the tailings pond, sandbars, stream sediments, fjord sediments, and integrated samples of floodplain surfaces (0–25 cm). In total 734 samples were collected. Chemical analysis (ICP-AES after aqua regia or HNO3 extraction) showed that overbank sediments at a certain depth represent the pre-industrial trace metal concentrations within the drainage basin. The tailings and recent fluvial sediments were enriched in approximately the same element suite. The highest enrichment factors were obtained for Cu (8–53) and Mo (22–57). Fluvial processes in the tailings pond have probably selectively eroded fine-grained, low-density particles. Thus, coarse chalcopyrite may have been left behind, while molybdate associated with fine-grained particles may have been selectively entrained causing dilution of Cu and enrichment of Mo in the downstream fluvial sediments. In the sandbars, the highest Cu and Mo concentrations were found in fine-grained sediments downstream of a low-gradient reach that act as a bedload trap. On the floodplains, it is seen that the first areas to be inundated in a flood situation (proximal to the river and in depressions) have the highest metal concentrations. For regional geochemical mapping it is suggested that overbank sediment profiles along river reaches with a laterally stable or slowly migrating channel, should be sampled. In such floodplains, pre-industrial overbank sediments are usually preserved at depth. In case of laterally unstable reaches upstream of the sampling point, polluted and unpolluted sediments may be interlayered or mixed. Therefore, samples should be collected from various depths or sedimentary units in such profiles. A similar sampling strategy should probably be adopted to detect vertical migration of elements especially in areas with acid rain and low bedrock buffer capacity. To obtain high contrasts between polluted and unpolluted drainage basins, the overbank sediment profiles should be within the proximal part of the floodplain.  相似文献   

15.
Ag, Pb, Sn and Zn ores have been intensively mined and processed at Cerro Rico de Potosí, Bolivia since 1545. Acid mine drainage (AMD) and mineral processing plant effluent are prime sources of water contamination in the headwaters of the Upper Rio Pilcomayo watershed. Streams receiving AMD drainage from the slopes of Cerro Rico and surrounding landscapes were sampled during the dry (July–August 2006) and wet (March 2007) seasons of one water-year. In-stream waters contained total metal concentrations of up to 16 mg/L As, 4.9 mg/L Cd, 0.97 mg/L Co, 1,100 mg/L Fe, 110 mg/L Mn, 4.1 mg/L Pb, and 1,500 mg/L Zn with pH ranging from 2.8 to 9.5. AMD-impacted streams contained elevated concentrations of the same major ecotoxic constituents present in AMD discharges at concentrations orders of magnitude greater than in those streams unimpacted by AMD. Many of the AMD impacted water bodies are more degraded than class “D” of the Bolivian receiving water body criteria, rendering them unfit for domestic or agricultural use. Natural attenuation is insufficient to render waters safe for use, however, some of these waters are currently being utilized for irrigation and livestock watering. The data indicate that historic and current mining activities have transformed these key natural resources into potential human and environmental health hazards.  相似文献   

16.
湘西金矿尾矿—水相互作用：1．环境地球化学效应   总被引：8，自引：2，他引：8  
湘西金矿在生产过程中产生了大量的尾矿。该区尾矿－水相互作用强烈，并引起了尾矿中重金属元素的释放、迁移和对水体－土壤、蔬菜等表生环境的重金属污染。污染程度较大的元素均为Au、Sb、As、Cd、Hg、W等，与尾矿中元素的富集特征相一致。尾矿中重金属元素的水迁移能力由大到小顺序为Au、Cd、W、Sb、Pb、As、Zn、Cu。元素的生物吸收系数由大至小顺序为Cd、Au、Zn、Hg、Sb、Cu、Pb、As、W。植物中金属元素浓度主要受土壤中的浓度、植物种类和吸收的影响。  相似文献   

17.
Monitoring of heavy metal transfers, aerial deposition and fluvial transport to soil, stream sediment and vegetation compartments surrounding two former PbZn mines are reported. Results show that 80–100 a after the closure of the mines relatively large amounts of Cd, Pb, Zn and, in once case, Cu are entering the soil and fluvial systems.Aerial deposition of heavy metals within a 300 m radius of the centre of the tailings heaps is shown to be contributing up to 3.3 kg Cd, 71 kg Cu, 373 kg Pb and 1041 kg Zn annually to the surrounding soil and vegetation compartments. It is shown that more than 4.2 kg Cd/a and 1387 kg Zn/a are being transferred from the tailings heaps via the streams in the form of dissolved load. However, the greatest quantities of Cu (38 kg/a) and Pb (74 kg/a) are transported from the heaps as wash load. Transfers calculated as percentages of the total metal quantities in the tailings heaps highlight the greater relative mobility within the fluvial system of Cd and Zn compared to Cu and Pb. Outside of the tailings heaps, the greatest accumulation of metals is in the surrounding soil, while the smallest was observed to occur in the surrounding mixed grassland vegetation.The most important implications of these findings are in the long-term release and partitioning of pollutant metal species from historic metalliferous mine tailings within the terrestrial and fluvial environments. This information is of major ecotoxicological and agronomic importance and is necessary for the effective reclamation and remediation of such contaminated sites.  相似文献   

18.
湘江入湖河段沉积物重金属污染及其Pb同位素地球化学示踪   总被引：12，自引：0，他引：12  
湘江是我国重金属污染最严重的河流之一.本次工作利用等离子质谱(ICP-MS)和多接收同位素质谱(MC-ICP-MS)等技术,对湘江入湖河段沉积物进行了系统的重金属微量元素和Pb同位素分析.结果表明,湘江河床沉积物明显富集Bi、Sc、V、Mn、Ni、Cu、Zn、Pb、Cd、Sn、Sb等多种重金属微量元素,而湖盆沉积物重金...  相似文献   

19.
The Ingurtosu Pb-Zn mine, situated in the southwestern part of Sardinia, has been in production from the beginning of the last century up to 1968. The orebody consists of galena/sphalerite/barite/siderite veins in Ordovician arenaceous and phyllitic sediments, near the contact with a Hercynian batholith.

Abundant tailings were collected in a pond from which they were discharged during the winter months into the sea via the Rio Naracauli stream. Today this area of outstanding scenic beauty, is degraded by tailings and waste rock scattered all along the stream.

Material derived from mining activities was studied for grain size, mineralogical and geochemical composition. The Rio Naracauli was sampled over a length of ten kilometers at regular intervals.

The results can be summarized as follows: (a) tailings contain a varying, but often quite high, percentage of Pb; lower percentages were found for Zn and Cd; (b) a sharp increase in dissolved Zn, Cd and Pb was observed in the Rio Naracauli where it leached the tailings; and (c) tailings and waste rocks should be recycled or revegetated.  相似文献   


20.
Overbank sediments of the Geul River (East Belgium) are highly contaminated by the heavy metals Pb, Zn, and Cd due to former Pb-Zn mining activities in the drainage basin. Geochemical variations in vertical overbank sediment profiles sampled 1 km north of the mine tailings of Plombiéres allow metal fluxes back to the 17th century to be reconstructed. The vertical profiles are subdivided into three major units corresponding to different industrial periods based on sedimentological criteria as well as on the distribution of contaminants. Alluvial sediments with the highest heavy metal concentrations correspond to the major period of mining activity of the 19th century. The fact that Zn mining at the La Calamine open mine started before large-scale mining of the PbS-ZnS subsurface exploitations is reflected in the vertical profiles by an increase in Zn content before a marked increase in Pb and Cu. The regional extent of contamination in the alluvial deposits was evaluated on the basis of the geochemical analysis of sediments at depths of the 0–20 cm and 80–100 cm. Most of the upper samples are extremely contaminated. Significant local variations in heavy metal concentration in the lower samples are interpreted in terms of which overbank sediment horizon has been sampled at a depth of 80–100 cm. This indicates that blind sampling of overbank sediments to characterize the degree of contamination in shallow boreholes can give very erratic results.  相似文献   

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