Influence of the Aznalcóllar mining spill on the vertical distribution of heavy metals in sediments from the Guadalquivir estuary (SW Spain)

The Natural Park of Do?ana and the Guadalquivir estuary were impacted by the release of 6 million cubic meters of acid waste after the mine-tailing spill in Aznalcóllar (Andalusia, SW, Spain). Here is presented the monitoring of the accidental spill on vertical distribution of heavy metals in the estuarine sediments. The total concentration of six metals (Fe, Mn, Zn, Cd, Pb, Cu), their chemical speciation and the organic carbon concentration were analyzed in sediment vertical profiles. The results obtained determine background levels similar to previously reported in the area. The analysis catalogues the impact of the accident on the estuary as acute and mainly associated with high concentrations of Zn and Cd. The recent enrichment in Zn and Cd and their geochemical association with the more mobile fractions of the sediment determine an environmental risk associated with the acute impact and detected in some of the areas of the estuary.     

Assessment of heavy metal contamination in the sur?cial sediments from the lower Meghna River estuary,Noakhali coast,Bangladesh

Sediment samples were collected from ten selected sites of the lower Meghna River estuary, and six heavy metals were analyzed with Atomic Absorption Spectrophotometry(AAS) to assess the contamination level and the metals' association with sediment grain size. The current results revealed that the mean concentrations of the studied metals were ranked in descending order of iron(Fe)(1.29 ? 103 mg/kg) zinc(Zn)(42.41 mg/kg) lead(Pb)(12.48 mg/kg) chromium(Cr)(10.59 mg/kg) copper(Cu)(6.22 mg/kg) cadmium(Cd)(0.28 mg/kg). The geo-accumulation, contamination, and pollution load indexes suggested that the lower Meghna river estuary was not contaminated by Fe, Zn, Pb, Cr, and Cu.The mean size of the sediment ranged from 28.92 to 126.2 mm, and the Pearson correlation coefficient showed a significant association between Fe and Pb(coefficient of determination, r2? 0.836; p 0.05),and no significant correlation was found between individual metals and grain size, indicating no or low influence on the metals distribution.     

Temporal distribution of heavy metal concentrations in oysters Crassostrea rhizophorae from the central Venezuelan coast

The oyster Crassostrea rhizophorae is a bivalve abundant in Venezuelan estuaries and consumed by local populations. No known values have been reported on trace metals in oysters from the central Venezuelan coast. We report the concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V and Zn in the soft parts of C. rhizophorae, which were collected bimonthly between March 2008 and March 2009, at two sampling areas from the Central Venezuelan Coast: Buche estuary and Mochima estuary. Our results show that for each metal there is a similar temporal variation pattern. The concentrations of the heavy metals reported in this work are useful as reliable baselines and can be used for comparison in future environment studies. Concentrations in C. rhizophorae from the Buche estuary can be interpreted to be high on a global scale for Cd, Cu, Ni and Mn, indicating atypically raised bioavailabilities.     

Assessment of arsenic and heavy metal pollution and ecological risk in inshore sediments of the Yellow River estuary,China

In order to investigate the pollution levels, sources and ecological risks of arsenic (As) and heavy metals (Cr, Ni, Cu, Zn, Pb and Cd) in inshore sediments of the Yellow River estuary, the surface sediment in areas of inshore coastal waters were sampled in October 2014 as the flow-sediment regulation project (FSRP) was implemented for 13 years. Results showed that the concentrations of As and heavy metals in inshore sediments of the Yellow River estuary were in the order of Zn?>?Cr?>?Cu?>?Ni?>?Pb?>?As?>?Cd. Higher levels of As, Cr, Ni, Cu, Zn and Pb generally occurred in fine-grained sediments of the Yellow River estuary and the southeast region, which was consistent with the spatial distribution of clay. In contrast, higher concentrations of Cd were generally observed in northwest area of the Yellow River estuary and near the Qingshuigou estuary, which showed similarly spatial distribution with that of sand. The sediment quality guidelines (SQG_S) and geoaccumulation indices (I_geo) indicated that the inshore sediments were polluted by Cu, Cd, As, Pb and Zn, and, among them, Cd pollution was more serious. Ecological risk indices (E _r ⁱ ) demonstrated low risks for Cr, Ni, Cu, Zn, Pb and As, and high potential toxicity by Cd. The integrated ecological risk index implied that 6.8% of stations presented moderate risk, 4.5% of stations exhibited disastrous risk, and 88.7% of stations demonstrated considerable risk. Principal component analysis indicated that Ni, Cu, Zn, Pb and As might originate from common pollution sources, while Cr and Cd might share another similar sources. With the continuous implementation of FSRP, As and heavy metal levels in inshore sediments of the Yellow River estuary could be classified as stage I (2002–2010) and stage II (2010–2014). In the stage I, As, Cr, Ni, Cu, Zn and Pb levels fluctuated but decreased significantly, whereas Cd concentrations showed little variation. In the stage II, As and heavy metal levels significantly increased although some little fluctuations occurred. The continuous accumulation of As and heavy metals (especially for Cd) in inshore sediments of the Yellow River estuary would occur again as the FSRP was implemented for 9 years (since 2010). The ecotoxicological risk of Cd, As, Ni and Cu in inshore sediments might be more serious since the accumulation of the four elements would be continuously occurred in future years. Next step, there will be long-term potential consequences for marine organism if effective measures are not taken to control the loadings of metal pollutants into estuary.     

Sediment quality in the Guadalquivir estuary: lethal effects associated with the Aznalcóllar mining spill

Monitoring from 1998 to 2001 has assessed the impact of the Aznalcóllar mining spill on the sediment quality in the Guadalquivir estuary. Chemical analysis has been completed with biological effects measured in different organisms. The toxicity of sediments obtained from dilutions of toxic mud and from environmental stations affected by the accidental spill was tested using the amphipod Ampelisca brevicornis and the clam Scrobicularia plana.The results obtained show that amphipods are more sensitive to the accidental spill than the clams. A dilution of clean sediment by more than 1.8% of toxic mud produced 100% mortality of amphipods. In GR2 station is detected toxicity to amphipods but not to clams. The rest of the environmental stations show no toxicity. Toxicity to amphipods in GR2 station decreased along time (from 50% to 60% of mortality in 1998 to 10 to 15% in 2001) and it can be associated with a recovery of the areas impacted by the accidental spill.     

Comparison of the role of two Spartina species in terms of phytostabilization and bioaccumulation of metals in the estuarine sediment

In the joint estuary of the Odiel and Tinto rivers (SW Spain), the invasive Spartina densiflora Brongn. and the native Spartina maritima (Curtis) Fernald are growing over sediments with extreme concentrations of heavy metals. The contents of As, Cu, Fe, Mn, Pb and Zn were determined in sediments, rhizosediments and different tissues of both species, from Odiel and Tinto marshes. S. densiflora showed a higher capability to retain metals around their roots and to control the uptake or transport of metals, mediated by a higher formation of plaques of Fe/Mn (hydro) oxides on the roots. At the Tinto marsh, there were no differences between the metal concentrations of the sediment and those of the rhizosediment, a fact that could be explained by the extremely high concentrations of metals which can pass over a threshold value, altering the properties of root cells and preventing roots from acting as a ‘barrier’ to the uptake or transport of metals.     

Assessment of heavy metal contamination in the surficial sediments from the lower Meghna River estuary,Noakhali coast,Bangladesh

Sediment samples were collected from ten selected sites of the lower Meghna River estuary,and six heavy metals were analyzed with Atomic Absorption Spectrophotometry(AAS)to assess the contamination level and the metals’association with sediment grain size.The current results revealed that the mean concentrations of the studied metals were ranked in descending order of iron(Fe)(1.29×103 mg/kg)>zinc(Zn)(42.41 mg/kg)>lead(Pb)(12.48 mg/kg)>chromium(Cr)(10.59 mg/kg)>copper(Cu)(6.22 mg/kg)>cadmium(Cd)(0.28 mg/kg).The geo-accumulation,contamination,and pollution load indexes suggested that the lower Meghna river estuary was not contaminated by Fe,Zn,Pb,Cr,and Cu.The mean size of the sediment ranged from 28.92 to 126.2 mm,and the Pearson correlation coefficient showed a significant association between Fe and Pb(coefficient of determination,r2=0.836;p<0.05),and no significant correlation was found between individual metals and grain size,indicating no or low influence on the metals distribution.     

鄱阳湖饶河段重金属污染水平与迁移特性

鄱阳湖饶河入湖段是鄱阳湖重金属污染最严重的水域之一,为了研究其污染现状,本文于2005年3月平水期对鄱阳湖饶河段的水体、底泥、土壤及水生植物的重金属污染水平及迁移特性进行了调查与分析．结果表明,饶河段水体中的重金属除Pb的含量超出地表水环境质量标准Ⅲ类标准外,其它各项监测指标均能达到地表水环境质量Ⅲ类标准．饶河段底泥及河滩土壤的重金属含量平均值与国家土壤环境质量相比,Zn、Cd的平均值超出了三级标准,而Cu、Pb的含量指标均符合三级标准;通过地质积累指数评价结果表明,饶河段重金属底泥除Zn污染为中度污染以外,其他各种重金属污染为轻度污染或偏中度污染,且饶河段底泥中Cu、Zn、Ph三种重金属元素之间呈极显著正相关．饶河段水生植物对Cu、 Zn、Ph都有不同程度的富集;根据富集系数评价表明,植物对Cu的平均富集能力相对较强些,其次是Pb和Zn,多数水生植物表现出对Cd具有一定的抗性．     

Copper,zinc, cadmium,nickel, iron and manganese in the Southern Bight of the North Sea

Ni, Cd, Cu, Zn, and Fe were determined in water and suspended matter samples and Mn in suspended matter samples from the Southern Bight region of the North Sea. Four distinct areas, comprising the Rhine estuary, the Dutch coastal waters, the centre of the Bight, and the English coastal water can be distinguished on the basis of the distribution of the trace metals. The total concentrations of all metals were high in the Rhine estuary, decreased in a seaward direction to reach very low values, comparable to continental shelf water, in the centre of the Bight, and increased again towards the English coast. Elevated concentrations of dissolved Cu, Ni, Cd and Zn near the English coast are not only due to river inputs. Over the entire region, the fraction of Cd, Ni and Zn in solution was consistently more important than the fraction in the suspended particulate phase. In contast, the fraction of Fe and Mn in the solid phase was consistently greater than the fraction in solution. Total concentrations of Fe, Mn and Cu are more dictated by the suspended particulate matter concentration than Cd, Ni and Zn.     

Spatial and temporal variations of heavy metal contamination in sediments of a mangrove swamp in Hong Kong

Spatial and temporal variations of heavy metal contamination in sediments of a small mangrove stand in Hong Kong were examined by laying two transects perpendicular across the shore. Surface sediment samples were taken along the two transects running landward to seaward at intervals of 5 or 10 m during December 1989, and March, July and September 1990. Total concentrations of Cu, Zn, Mn and Pb did not show any specific trend along each transect, although the maximum concentration of heavy metals tended to occur at the landward edge. There was a high level of variability among locations within each transect; for instance, the Cu concentrations fluctuated from 1 to 42 μg g⁻¹. Certain sites contained exceptionally high levels of total metals. Total concentrations of Cu, Zn, Mn and Pb as high as 42, 150, 640 and 650 μg g⁻¹, respectively, were recorded, implying contaminated sediment. A comparison of the two transects indicated that the sediments of Transect B seemed to contain higher total Zn but lower Cu and Mn concentrations than those of Transect A. Most of the heavy metals accumulated in the sediments were not extractable with ammonium acetate and no Cu or Pb was detected in these extracts. The concentrations of extractable Zn and Mn were low, less than 10% of the total metal concentration in the sediment, and appeared to decrease from the landward to seaward samples. For both total and extractable metals, there were significant seasonal fluctuations for both transects, but no specific trends could be identified. These spatial and temporal variations suggest that the scale and representativeness of sampling require careful planning, and a single sample might not give a satisfactory evaluation of the levels of heavy metal contamination in mangrove ecosystems.     

Speciation of heavy metals on suspended sediment under high flow conditions in the River Aire,West Yorkshire,UK

Concentrations of heavy metals (Cd, Cu, Pb and Zn) on suspended sediments during a flood event at Thwaite Mills, River Aire, were analysed using a five step sequential extraction technique to determine their major chemical associations (exchangeable, surface oxide and carbonate, Fe and Mn oxides, organic and residual metal ions). Total metal concentrations were lowest at higher discharges, resulting from dilution by clean sediment. The major transport fractions are the Fe and Mn oxides, which carry 29% of the total metals. Knowledge of the chemical forms of heavy metals on suspended sediment is essential for estimating their biological availability and physicochemical reactivity. © 1998 John Wiley & Sons, Ltd.     

Spatial variability of metals in the inter-tidal sediments of the Medway Estuary,Kent, UK

Concentrations of major and trace metals were determined in eight sediment cores collected from the inter-tidal zone of the Medway Estuary, Kent, UK. Metal associations and potential sources have been investigated using principal component analysis. These data provide the first detailed geochemical survey of recent sediments in the Medway Estuary. Metal concentrations in surface sediments lie in the mid to lower range for UK estuarine sediments indicating that the Medway receives low but appreciable contaminant inputs. Vertical metal distributions reveal variable redox zonation across the estuary and historically elevated anthropogenic inputs. Peak concentrations of Cu, Pb and Zn can be traced laterally across the estuary and their positions indicate periods of past erosion and/or non-deposition. However, low rates of sediment accumulation do not allow these sub surface maxima to be used as accurate geochemical marker horizons. The salt marshes and inter-tidal mud flats in the Medway Estuary are experiencing erosion, however the erosion of historically contaminated sediments is unlikely to re-release significant amounts of heavy metals to the estuarine system.     

Dissolved trace metal distributions in Port Jackson estuary (Sydney Harbour), Australia

Concentrations of dissolved metals (Cd, Cu, Ni, Mn and Zn) were determined for summer and winter, under low-flow conditions in Port Jackson, a microtidal, well-mixed estuary in south-east Australia. Mean concentrations of Cd (0.04+/-0.02 microg/l), Ni (0.86+/-0.40 microg/l), Mn (20.0+/-25 microg/l) and Zn (6.47+/-2.0 microg/l) were below water quality guidelines. Concentrations of Cu (1.68+/-0.37 microg/l), however, slightly exceeded recommended values. Dissolved Ni and Mn behaved mostly conservatively, whereas Cd, Cu and Zn showed mid-estuarine maxima. Peaks in Cd, Cu and Zn concentrations were located in the upper estuary, independent of the salinity and suspended particulate matter loading, and were consistent with anthropogenic inputs of metals in the estuary. Concentrations of dissolved Cu were highest in summer, whereas concentrations of Cd, Ni and Mn were significantly lower in summer than winter (P< or =0.05). The increase in temperature and biological activity during summer explained the seasonal variation. The sequence of log K(d) values (20-30 salinity) was Mn>Zn>Cu>Ni. These results give unique information concerning the contemporaneous distribution of dissolved trace metals in the Port Jackson estuary and they provide a data set against which the long-term contamination may be assessed.     

Sediment quality in the Guadalquivir estuary: sublethal effects associated with the Aznalcóllar mining spill

As a complementary assessment of the impact of the Aznalcóllar mining spill on the Guadalquivir estuary two different sediment toxicity tests using fish (Solea senegalensis) and clams (Scrobicularia plana) were performed. The histopathological alterations by recording lesions at 15 and 30 days in fish to the gills, liver, gut and kidney and at 14 days in clams to the gills and gut were used to determine the adverse effects associated with the contaminants bound to sediments. The lesions measured at different tissues in both organisms show that the enrichment of heavy metals from the mining spill stressed some areas in the ecosystem of the estuary. The comparison of these effects with those lethal effects detected in the same samples using a multivariate analysis approach permits to identify the adverse effects associated with the accidental spill on the estuary. The incidence of the impact, located in specific areas of the estuary show an acute effect related to the spill.     

Metal exposure and biological responses in resident and transplanted blue mussels (Mytilus edulis) from the Scheldt estuary

The Western Scheldt river and estuary is known to be highly polluted as it receives industrial, agricultural and domestic effluents from one of the most populated and industrialised zones in Europe. Aquatic organisms are exposed to pollutants, specifically metals that are present in different environmental phases, e.g. dissolved, suspended material or sediment phases. The objective of this study was to study the relationship that exists between environmental metal levels, the degree of metal uptake by aquatic organisms with the concomitant biological responses. For this purpose the bivalve mollusk, Mytilus edulis, was selected as bioaccumulation indicator organism. Environmental (water and sediment) and mussel samples were collected during the late winter (March 2000) from sampling sites in the Scheldt estuary. Sites were selected to represent a salinity gradient from the mouth of the estuary to the furthest distribution area of mussels upstream in the system. Together with standard water quality parameters (e.g. salinity, dissolved oxygen, dissolved organic carbon, etc.) concentrations of twelve metals were analysed in the water (dissolved and suspended matter) and sediments. Levels of these metals were also measured in the soft tissue of M. edulis, together with concomitant biomarker responses in resident mussel populations at each site. The biomarkers that were included in this study were condition index, scope for growth, survival in air, cell membrane stability, DNA damage, and metallothioneins. Data were subjected to multivariate statistical analysis. The physico-chemical parameters and metals in the environmental samples clustered the sites to reflect the distribution based on the salinity gradient. Bioaccumulation results revealed increased metal uptake along a pollution gradient with the highest metal bioaccumulation occurring at the upstream most sites and therefore closest to the in the industrial activities. However, the biomarker responses clustered the sites in a manner that reflected the influence of combination of internal exposure (bioaccumulation) and external exposure (physico-chemical conditions). These differences in biomarker responses clearly demonstrated were attributed to abiotic factors other than metal pollution alone e.g. localized short-term increases in increased suspended sediment concentrations and decreased dissolved oxygen concentrations.     

Metal exposure and biological responses in resident and transplanted blue mussels (Mytilus edulis) from the Scheldt estuary

The Western Scheldt river and estuary is known to be highly polluted as it receives industrial, agricultural and domestic effluents from one of the most populated and industrialised zones in Europe. Aquatic organisms are exposed to pollutants, specifically metals that are present in different environmental phases, e.g. dissolved, suspended material or sediment phases. The objective of this study was to study the relationship that exists between environmental metal levels, the degree of metal uptake by aquatic organisms with the concomitant biological responses. For this purpose the bivalve mollusk, Mytilus edulis, was selected as bioaccumulation indicator organism. Environmental (water and sediment) and mussel samples were collected during the late winter (March 2000) from sampling sites in the Scheldt estuary. Sites were selected to represent a salinity gradient from the mouth of the estuary to the furthest distribution area of mussels upstream in the system. Together with standard water quality parameters (e.g. salinity, dissolved oxygen, dissolved organic carbon, etc.) concentrations of twelve metals were analysed in the water (dissolved and suspended matter) and sediments. Levels of these metals were also measured in the soft tissue of M. edulis, together with concomitant biomarker responses in resident mussel populations at each site. The biomarkers that were included in this study were condition index, scope for growth, survival in air, cell membrane stability, DNA damage, and metallothioneins. Data were subjected to multivariate statistical analysis. The physico-chemical parameters and metals in the environmental samples clustered the sites to reflect the distribution based on the salinity gradient. Bioaccumulation results revealed increased metal uptake along a pollution gradient with the highest metal bioaccumulation occurring at the upstream most sites and therefore closest to the in the industrial activities. However, the biomarker responses clustered the sites in a manner that reflected the influence of combination of internal exposure (bioaccumulation) and external exposure (physico-chemical conditions). These differences in biomarker responses clearly demonstrated were attributed to abiotic factors other than metal pollution alone e.g. localized short-term increases in increased suspended sediment concentrations and decreased dissolved oxygen concentrations.     

Trace metals in harbour and slipway sediments from the island of Malta, central Mediterranean

Sediment samples collected from large harbours and public slipways on the island of Malta have been analysed for geochemically important metals (Al, Ca, Fe, Mn) and contaminant metals (As, Cd, Co, Cr, Cu, Ni, Pb, Sn, Zn) following fractionation (<63 μm) and digestion in aqua regia. Absolute and Al-normalised concentrations of contaminant metals exhibited relatively little dispersion both among different samples from the same location and between samples from different locations, notable exceptions including lower concentrations of Cr and Sn on the slipways than in the harbours. Sources of contaminant metals are attributed to diffuse and specific waste inputs from urban surroundings and boating and shipping activities. Overall, concentrations are similar to those reported for other large harbours in urban settings where equivalent sample fractionation-digestion has been performed. Relative to various sediment quality guidelines, Pb is predicted to exert the greatest threat to the marine environment of Malta.     

Metals contamination along the watershed and estuarine areas of southern Bohai Sea,China

Distributions and magnitude of metals in water, sediment and soil collected from the watershed and estuarine areas of southern Bohai Sea, were investigated. The largest dissolved concentrations of As, Cu and Zn in water were 347.70, 2755.00, 2076.00 μg/L, respectively, much higher than corresponding drinking water guidelines. The greatest concentrations of Cu, Zn, Cr, Ni, Pb, As and Cd in sediments were 1462.2, 1602.17, 196.43, 67.15, 63.54, 73.86 and 1.41 mg/kg, dw, respectively. The mean concentrations of Cu, Ni, Cd, Zn, Cr, Pb and As in soils were 24.67, 24.73, 0.14, 64.75, 56.52, 25.12 and 9.34 mg/kg, dw, respectively. Land use was confirmed to be an important factor of influence on soil metal concentrations. Metal contents along the watershed of Jie River were significantly greater than in other locations. The detection of metals in relatively high concentrations from different environmental matrices in this region indicates the necessity of further studies.     

Trace elements migrating from tailings to rock varnish laminated sediments in an old mining region from Nelson,Nevada, USA

The dispersion and influence of soluble and particulate trace elements(TEs) present in the materials from abandoned mines is an imminent problem on terrestrial and aquatic environments.The goal of this research is to provide a broader view of such transport,assessing particle size distribution and TE interactions(e.g.,scavenging) with mine tailings and locally derived sediments transported by water in arid region.Sand grains from wash sediment were collected from a dry ephemeral wash in Nelson,N...     

A regression model using sediment chemistry for the evaluation of marine environmental impacts associated with salmon aquaculture cage wastes

This study was undertaken to develop an approach for modelling changes of sediment chemistry related to the accumulation of aquaculture waste. Metal composition of sediment Al, Cu, Fe, Li, Mn, and Zn; organic carbon and < 63 microm particles were used to determine the extent of detectable effects around the cage. This study showed marked differences in the sediment chemistry between aquaculture sites and the natural background: (1) negative correlations between sediment Cu and Zn with Al, (2) poor correlations between metals and Li, and (3) concentrations of Fe and Mn decreased with increased accumulation of organic carbon. There is a trend among normalised metals, organic carbon and particles related to normal, hypoxic and anoxic sediment conditions. The trends are useful for detecting and assessing the cumulative effects from aquaculture wastes to the marine environment. Lithium is less interactive with other metals in aquaculture sediments compared with the natural background sediments. Principal components analysis (PCA) was carried out on the metals, organic carbon, and particles to cluster the similarities of the variables so as to establish the predicted or adjusted environmental monitoring program (EMP) ratings. This approach, using the adjusted EMP rating based on sediment chemistry, yields a regression model with R2 = 0.945 compared to R2= 0.653 for the regression model using unadjusted EMP for assessing the environmental conditions.