共查询到20条相似文献，搜索用时 38 毫秒
1.
C. W. Martin 《Environmental Geology》1997,30(1-2):119-125
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
2.
Chi Thanh Vu Chitsan Lin Kim Anh Nguyen Chien-Chuan Shern Yi-Ming Kuo 《Environmental Earth Sciences》2018,77(10):388
The Houjing River flows through Kaohsiung, the most industrialized city in southern Taiwan. In this study, heavy metal concentrations in water and sediments from samples along the river were investigated to illustrate metal contamination levels and call for the awareness of industrial pollution prevention. The heavy metal concentrations in the water samples were low and appear to pose little direct risk to aquatic life and irrigation, but heavy metal concentrations in the sediments are locally very high and present an environmental risk. Cadmium, Cu, and Zn were found in higher concentrations in the river sediments than those recommended in some sediment quality guidelines and findings of river sediments in similar studies worldwide. Hence, the ecological risk of heavy metal contamination in sediments was assessed using the pollution load index (PLI) and potential ecological risk index (RI). Three of the eleven sites sampled were found to have PLI values higher than 1 and 8 of them had ‘considerable’ to ‘very high’ RI values, suggesting a considerable ecological risk. These findings provide an insight into elemental metal contamination of the Houjing River and present a baseline data set, which will be critical for future development and environmental protection plans devised for the region. 相似文献
3.
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
4.
The distribution, accumulation, and ecological risk of heavy metals (Cu, Cd, Pb, Zn, Ni, Cr, and As) in the surface sediment were investigated in the upper reaches of Hunhe River, Northeast China. Sediment samples from 51 points throughout the upper reaches of Hunhe River were collected and measured for heavy metal concentrations, TN content, and TP content. Results showed that heavy metal concentrations at the vicinity of mines and towns were higher than those at other locations. According to sediment quality guidelines (SQGs), Cd and Zn were enriched in the sediments. The correlation analysis and principal component analysis (PCA) were conducted to assess the heavy metal sources. Close correlations between metal distribution and TP indicated that the sediments may be affected by application of phosphate fertilizer. Elements, Cu, Cd, Pb, Zn, and As, were grouped together, reflecting they were released from the same sources. PCA suggested that their primary sources were anthropogenic, namely mining and extensive use of fertilizers. Therefore, heavy metal pollution due to mining and agricultural intensification in the upper Hunhe River basin should be taken into account during the formation of regional management strategies for the water environment. 相似文献
5.
Multiple sedimentary units from floodplain reaches at Welshpool on the upper River Severn and at the confluence of the Afon Tanat and Afon Vyrnwy (mid‐Wales, UK) were examined to ascertain if they have distinctive particle size characteristics. Changes in particle size characteristics and their possible relationship to known human and climatic impacts are also discussed. Ellipse plots of particle size characteristics from the River Severn floodplain at Welshpool show that coarse‐grained outwash deposits can be clearly discriminated from channel margin or palaeochannel sediments. In contrast, at the Afon Tanat–Vyrnwy study reach, this discrimination is not seen so clearly. The relationships between age and particle size characteristics from the most sampled sedimentary environment, palaeochannel infills, were also examined. The data from the River Severn floodplain at Welshpool show that palaeochannel sediments reveal a gradual but clear increase in particle size from the mid‐ to late Holocene towards the present day. Sediments deposited in the period 90–160 years BP are markedly coarser. It is suggested that these changes may be related to the combined effect of land‐use changes, metal mining impacts and changes in flood frequency and magnitude that occurred at this time within the upper Severn basin. In contrast, the particle size characteristics of post Late Devensian/Early Holocene units from Tanat–Vyrnwy palaeochannels were random with no discernible age–size patterns. It is suggested that the non‐systematic grain size distribution may be due to the steeper valley gradients of the Tanat–Vyrnwy system (and by inference higher stream powers) and its relatively narrow valley form enabling more effective coupling between coarser outwash deposits found on and at the edges of hillslopes and the valley floor. Although the two study reaches have undergone comparable environmental change during the Holocene and lie in the piedmont zone of their catchments, palaeochannel units of the same age possess distinctly different characteristics. Intrinsic reach‐scale geomorphic factors would appear to preclude the uniform application of particle size characteristics to determine alluvial response to environmental change. Consequently, care needs to be applied to the use of such data for environmental discrimination because the phenomenon of equifinality means that a specific set of sediment characteristics is not necessarily exclusive to specific fluvial environments in either space or time. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
6.
7.
鸭绿江河口及近岸地区沉积物中重金属分布的影响因素分析 总被引：15，自引：1，他引：14
对鸭绿江河口不同地区沉积物中重金属分布特征和埋藏通量的垂向变化进行了分析;探讨了其独特的动力环境等因素对重金属分布的影响;评价了鸭绿江河口地区重金属污染状况及潜在生态风险程度.结果显示,自1920年代到2000年以来,除了Cu的含量和埋藏通量逐年减小之外,Cr、Ni、Zn、Cd、Pb、As和Hg的浓度和埋藏通量具有逐渐增加的趋势;鸭绿江河口地区重金属总体污染程度为重到严重,其中西水道沉积物的重金属总体污染程度和总潜在生态风险程度均最高,重金属污染已经对鸭绿江河口地区的生态环境构成了严重的危害;粒度控制效应不是鸭绿江河口地区重金属分布的最主要影响因素;Cu和其他几种重金属有着不同的来源;最大浑浊带独特的动力机制是造成中水道重金属(除Cu外)的高值分布区和最大浑浊带内的高悬沙浓度分布区相对应的最主要原因. 相似文献
8.
长江沉积物环境地球化学特征及生态风险评价 总被引：1，自引：0，他引：1
为了进行长江流域沉积物生态风险评价,对长江流域干流以及主要支流的沉积物统一进行采样分析。首先对其元素的组成特征及重金属元素的富集特征进行分析。常量元素含量在流域空间上的变化主要受其携带矿物含量变化的影响;Cu、Pb、Cd、As、Hg 5种微量元素富集程度较大,存在异常。同时采用潜在生态风险指数法对长江沉积物Cr、Mn、Co、Ni、Cu、Zn、Pb、Cd、As、Hg 10种元素进行了评价研究。结果表明,潜在生态风险指数较大的地区分布在湖南湘江、安徽铜陵等地区,中等的地区分布在四川、重庆及江西等地区,这些潜在污染指数与矿产的开采冶炼以及工业的布局有一定的关系,很大程度上是由人为因素造成的。从元素的潜在污染程度看,长江流域Cd、As、Hg污染程度较重,Cu、Zn、Pb次之,而Cr、Mn、Co、Ni基本没有污染。本研究为探讨长江流域沉积地球化学过程和环境保护提供了科学依据。 相似文献
9.
H. Leenaers 《GeoJournal》1989,19(1):37-43
The floodplain soils in the Guel basin have unacceptably high levels of pollution,v brought about by metal mining and related industrial activities in the past. Spoil heaps still exist along the Geul river and these are susceptible to erosion and leaching processes. An additional source of metals is formed by erosion of older, locally highly contaminated streambank deposits. These older sediments are polluted as a result of solid waste disposal containing metalliferous ore and tailings in the sand fraction. At present, these sediments function as a major source of heavy metals during high flow stages when streambanks are undermined and suspended sediments are deposited on the floodplains. The flood deposits have a relatively coarse texture, i.e. 70% dry weight in the fraction > 63 um.In order to obtain an indication about the potential mobility of the heavy metals in these deposits, 16 samples (8 samples < 63 um and 8 samples > 63 um) out of a set of 122 were subjected to a sequential extraction scheme as proposed by Calmano & Förstner (1983). It was found that up to 80% of the metals may be present in the first three leaching stages (exchangeable cations, carbonate fraction and easily reducible fraction) and that hardly any difference exists between the chemical partitioning of metals in the size fractions < 63 um and > 63 um. Moreover, as the total metal concentrations exponentially decrease along the 40 km distance away from the source area, the percentage of metals in these 3 potentially mobile fractions steadily increases. It is concluded that despite the rapid decay of total metal concentrations, Large amounts of potentially mobile metals are probably stored in the floodplain sediments even at a large distance from the source area. 相似文献
10.
Suspended and bed sediments collected from the entire region of the Godavari River basin were analyzed for Fe, Mn, Cr, Cu, Ni, and Zn. There are pronounced temporal and spatial variations in the heavy metal distributions. The concentrations of heavy metals in the suspended sediments are significantly higher than the bed sediments.Throughout the basin heavy metals are enriched in the finer fractions (<2 µm) of the bed sediments. The average heavymetal composition of the sediments is higher when compared to the average Indian river sediments. Heavy-metal concentration in the two shallow cores collected shows, to some extent, the influence of urbanization. When compared to the other tropical Indian rivers such as the Krishna, the Godavari appears to be a significant contributor of heavy metals to the Bay of Bengal. Considering the enormous sediment load of the Godavari River—170 million tons/yr, the heavy metal fluxes to the Bay of Bengal is very significant. Except for the Pranhita, other tributaries of the Godavari do not contribute significant loads of heavy metals. All the metals show high correlation among themselves and the correlation is more pronounced in suspended sediments than in the bed sediments. The heavy-metal distribution, fractionation, and its relationship with total suspended sediments and depth in various parts of the basin are discussed in detail. 相似文献
11.
An assessment study of heavy metal distribution within soil in upper course of Zarqa River basin/Jordan 总被引：1，自引：0，他引：1
Levels of heavy metals are found in soils and waters of the major tributary valleys of the Jordan Valley. Heavy metal content
in soils irrigated by treated waste water were measured for a 40 km reach of Zarqa River. Soil samples from eight different
sites along the upper course of this river were analyzed to determine the concentration of selected heavy metals (CO, Cr,
Cu, Pb, Ni, Zn). Silt forms the major component of the soils with an average of 54%. Clay fractions show an increase with
depth from 17 to 41%. Trends in particle size distribution and metal contents were compared across sample sites. Samples contained
moderate to considerable levels of Pb and Ni. Concentrations of Cu and Cr ranged between 33–59 and 65–90 ppm, respectively.
These values represent a slight to moderate class of pollution. The concentration of Cr shows a decrease with depth and distance
from the waste water plant. Cu, Zn, and Ni show increasing concentrations with depth but Pb and CO do not. The concentrations
of the measured heavy metals increases near the waste water treatment plant but decreases with distance from the plant due
to precipitation in the stream bed and dilution with stream water. This decline in metal content with distance from the treatment
plant suggests that most metals reaching floodplain soils may derive from the same source. Although current metal concentrations
are low to moderate, floodplain surface soils in this area should be regarded as a potential source for future heavy metal
pollution downstream. 相似文献
12.
Chemical analyses were done on cores of bottom sediment from three locations in Lake Livingston, a reservoir on the Trinity
River in east Texas to identify trends in water quality in the Trinity River using the chemical record preserved in bottom
sediments trapped by the reservoir. Sediment cores spanned the period from 1969, when the reservoir was impounded, to 1992,
when the cores were collected. Chemical concentrations in reservoir sediment samples were compared to concentrations for 14
streambed sediment samples from the Trinity River Basin and to reported concentrations for soils in the eastern United States
and shale. These comparisons indicate that sediments deposited in Lake Livingston are representative of the environmental
setting of Lake Livingston within the Trinity River Basin. Vertical changes in concentrations within sediment cores indicate
temporal trends of decreasing concentrations of lead, sodium, barium, and total DDT (DDT plus its metabolites DDD and DDE)
in the Trinity River. Possible increasing temporal trends are indicated for chlordane and dieldrin. Each sediment-derived
trend is related to trends in water quality in the Trinity River or known changes in environmental factors in its drainage
basin or both.
Received: 6 October 1995 · Accepted: 13 October 1995 相似文献
13.
H. Wittmann F. von Blanckenburg J.L. Guyot A. Laraque C. Bernal P.W. Kubik 《Journal of South American Earth Sciences》2011,31(1):45-53
Cosmogenic nuclide-based denudation rates and published erosion rates from recent river gauging in the Napo River basin (Peruvian Amazonia) are used to decipher erosion and sedimentation processes along a 600 km long transect from the headwaters to the lowlands. The sediment-producing headwaters to the Napo floodplain are the volcanically active Ecuadorian Andes, which discharge sediment at a cosmogenic nuclide-based denudation rate of 0.49 ± 0.12 mm/yr. This denudation rate was calculated from an average 10Be nuclide concentration of 2.2 ± 0.5 × 104 at/g(Qz) that was measured in bedload-derived quartz. Within the Napo lowlands, a significant drop in trunk stream 10Be nuclide concentrations relative to the Andean hinterland is recorded, with an average concentration of 1.2 ± 0.5 × 104 at/g(Qz). This nuclide concentration represents a mixture between the 10Be nuclide concentration of eroded floodplain deposits, and that of sediment eroded from the Andean hinterland that is now carried in the trunk stream. Evidence for addition of sediment from the floodplain to the trunk stream is provided by published decadal-scale sediment flux measurements from gauging stations operated in the Napo basin, from which an increase from 12 × 106 t/yr at the outflow of the Andes to ～47 × 106 t/yr at the confluence with the Solimões (upper Amazon River) is recorded. Therefore, approximately 35 × 106 t of floodplain sediment are added annually to the active Napo trunk stream. Combined with our nuclide concentration measurements, we can estimate that the eroded floodplain deposits yield a nuclide concentration of ～0.9 × 104 at/g(Qz) only. Under steady state surface erosion conditions, this nuclide concentration would translate to a denudation rate of the floodplain of ～0.47 mm/yr. However, we have no geomorphologic explanation for this high denudation rate within the low relief floodplain and thus suggest that this low-nuclide concentrated sediment is Andean-derived and would have been deposited in the floodplain at a time when erosion rates of the Andes were elevated. Therefore, the recently eroded floodplain sediment provides an Andean “paleo denudation rate” of 1.2 mm/yr that was calculated for high Andean production rates. A likely period for elevated erosion rates is the LGM, where climate and vegetation cover of the Andes differed from that of the Holocene. A possible cause for the erosion of the floodplain is the tectonic uplift of the Eastern Andes, which progressively shifts the Napo River northwards. Hence, the river cuts into ancient lowland sediment, which is admixed to the Andean sediment carried in the main Napo River. 相似文献
14.
对于雨洪河流,河流年输沙量主要来源于1场或几场高强度暴雨洪水过程,开展流域次洪输沙规律研究对认识流域水沙变化特性、提升流域产输沙的预测能力具有重要意义。利用嘉陵江流域小河坝站、罗渡溪站、武胜站及北碚站的历年场次洪量与输沙量资料,基于径流侵蚀功率理论和M-K分析等方法,系统分析了嘉陵江不同区域的次洪输沙特性。结果表明:嘉陵江流域汛期洪量和输沙量主要来自于嘉陵江干流;嘉陵江不同区域场次洪量均呈不显著减少趋势,次洪输沙模数（输沙量）总体呈显著减少趋势,但小河坝站2013—2020年次洪输沙模数（输沙量）呈显著增加趋势;随着径流侵蚀功率的逐渐增加,各区域不同时段的次洪输沙模数（输沙量）的变幅逐渐减小;嘉陵江干流区武胜站场次洪水输沙过程受人类活动影响最大、渠江罗渡溪站次之、涪江小河坝站最小;受汶川地震及强降雨等影响,小河坝站和北碚站2013—2020年次洪输沙量较1999—2012年有一定程度增加,但北碚站增幅小于小河坝站。 相似文献
15.
The distribution and concentration of metals and metalloids in the floodplain of the Clark Fork River of western Montana, USA, are mainly controlled by post-depositional diagenetic mechanisms of metal fractionation. Due to the influx of wastes into the river's headwaters from mining processes around the turn of the century, extensive amounts of contaminated material were deposited onto the floodplain. Tailings were deposited as widespread overbank deposits and point bars adjacent to abandoned channels, and are characterized by orange and gray mottled sediment, which is devoid of vegetation and covered by a blue metal sulfate precipitate during dry periods. Examination of stratigraphic profiles of floodplain sediment indicates three periods of deposition: 1) pre-mining, represented by coarse sand and organic overbank deposits under reducing conditions; 2) syn-mining, characterized by transition sediments and tailings deposits under oxidizing conditions; and, 3) post-mining, distinguished by grass-bound topsoil.Sites were established where sediments and water throughout the stratigraphic section were collected and analyzed. Chemical analyses indicate enriched concentrations of cadmium, copper, manganese, and zinc in sediments and porewater, and arsenic in groundwater, in areas contaminated by tailings deposits. Vertical trends in concentrations of metals show that they are distributed based on apportionment of metal phases between reducing-oxidizing environments and pH fluctuations. 相似文献
16.
Alicia Kirschbaum Jesica Murray Emilce López Ahinoam Equiza Marcelo Arnosio Geraldo Boaventura 《Environmental Earth Sciences》2012,65(2):493-504
The Yacoraite River and its tributaries run down the eastern slope of the Aguilar Range. It is one of the tributaries of the
Rio Grande, located in Quebrada de Humahuaca, a UNESCO World Heritage site. The Aguilar underground mine (Pb–Ag–Zn) is located
in the upper reaches of the Yacoraite River drainage basin. The aim of this work is to characterize the presence of heavy
metals in water and sediments of the Yacoraite River and to identify their sources. The analysis shows the seasonal variation
of heavy metals concentration in water and their relation with the World Health Organization (WHO) limits established for
human consumption. The Yacoraite basin is naturally anomalous in some metals and some elements, such as As which is controlled
by the chemical composition of regional lithology. During the wet season, Al, Co, Mo and Pb concentrations in water samples
are higher than during the dry season; in addition, these metals are also higher than WHO limit values. High enrichment factors
for Ba, Mo, Pb, Zn and Cd were found in Casa Grande stream, indicating the direct influence of the mining activities. Cd,
Pb and Zn are present in the Aguilar ore minerals, such as sphalerite and galena. Sediments collected during the dry season
show a drastic increase in the concentration of As, Pb, Ba, Zn, Cd and Mn. The Müller geo-accumulation index in Casa Grande
indicates that it is a highly polluted stream. The concentrations of As, Pb, Ba, Zn, Cd are also high in Yacoraite River: Security Quality Guidelines indicates
toxicity. A decrease in enrichment factors and geo-accumulation indices observed in sediments indicates the occurrence of precipitation/adsorption
processes in the river to restore the equilibrium composition. Strict environmental controls in Aguilar Mine are necessary
to avoid the uncontrolled input of toxic metals in Casa Grande stream and Yacoraite River. 相似文献
17.
18.
《Applied Geochemistry》2000,15(5):567-581
The Pearl River estuary is created by the inflow of freshwater from the largest river system that drains into the South China Sea. In recent years, massive economic growth and development in the region has led to excessive release of waste into the environment. The accumulation of contaminants in sediments is likely to pose serious environmental problems in surrounding areas. The study of sediment profiles can provide much information on the metal contamination history and long term potential environmental impacts. In this project, 21 core samples (up to 3.65 m deep) were collected in the Pearl River estuary. About 15 subsamples from each core were analysed for moisture content, total organic matter (L.O.I.), particle size and heavy metal and major element concentrations. The results show that Pb and Zn contents are elevated in the sediments at most of the sampling sites. Compared with historical monitoring results, the sediment metal contents have increased over the last 20 a, particularly for Pb. The west side of the Pearl River estuary tends to be more contaminated than the east side due to the contaminants inputs from the major tributaries and different sedimentation conditions. There are close associations between Fe, Co, Ni and Cu concentrations in the sediments. Zinc and Pb contents in the sediment profiles reflect a combination of the natural geochemical background, anthropogenic influences and the mixing effects within the estuary. The distribution of Pb in the sediments shows strong influences of atmospheric inputs, probably from the coal burning activities in the region. 相似文献
19.
Heavy metal contamination in overbank sediments of the Geul river (East Belgium): Its relation to former Pb-Zn mining activities 总被引：1，自引：0，他引：1
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
20.
Lionel F. Villarroel Jerry R. Miller Paul J. Lechler Dru Germanoski 《Environmental Geology》2006,51(2):283-299
An intense, but localized rainfall event in February 2003, led to the severe erosion and failure of a tailings disposal impoundment at the Abarόa Antimony Mine in southern Bolivia. The failure released approximately 5,500 m3 of contaminated tailings into the Rio Chilco-Rio Tupiza drainage system. The impacts of the event on sediment quality are examined and compared to contamination resulting from historic mining operations in the headwaters of the basin. Of primary concern are contaminated floodplain soils located along downstream reaches of the Rio Tupiza which were found to contain lead (Pb), zinc (Zn), and antimony (Sb) concentrations that locally exceed Canadian, German, and Dutch guidelines for agricultural use. Spatial patterns in sediment-borne trace metal concentrations, combined with Pb isotopic data, indicate that Pb, Zn, and Sb are derived from three tributary basins draining the Abarόa, Chilcobija, and Tatasi-Portugalete mining districts. Downstream of each tributary, geographical patterns in trace metal concentrations reflect local geomorphic changes throughout the drainage system. Trace metal concentrations within the Rio Chilco decrease rapidly downstream as a result of dilution by uncontaminated sediments and storage of metal enriched particles (e.g., sulfide minerals) in the channel bed as a result of ongoing aggradation. Storage in the floodplains is limited. These processes significantly reduced the dispersal and, thus, the relative environmental affects of tailings eroded from the Abarόa Mine during the 2003 flood. In contrast, storage of Pb, Zn, and Sb in floodplains along the Rio Tupiza is significant, the majority of which is derived from historic mining operations, particularly mining within the Tatasi-Portugalete district. 相似文献