Heavy metals in Yeniçağa Lake and its potential sources: soil,water, sediment,and plankton

The distribution and accumulation of heavy metals (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Ba, Pb) in the water, sediments, plankton of Yeniça?a Lake, and its potential sources (creeks, sewage, artesian well, soil) were investigated during 1-year study period as monthly or seasonally. Element analyses were performed by ICP–MS. Results showed that the trace and toxic elements (Al, As, Mn, Pb, Fe) concentration in lake water and/or its feeding sources were above the recommended water standards (WHO, EC, EPA, TS-266). It was found that the maximum accumulation of the heavy metals iron, aluminum, manganese, zinc, and barium in the sediment of Yeniça?a Lake. The accumulation order of trace metals were Fe > Al > Mn > Zn > Ba > Ni > Cr > As > Cu > Pb > Co > Mo > Sn > Cd in the lake, creeks sediment, and soil samples. The similar results suggest that the accumulation of heavy metals in the sediment is a natural process. Metals accumulated in the lake are naturally mixed from the soil. However, the presence of heavy metals in the analysis of artesian well water and sewage reveals that the transportation occurs also from the groundwater to the lake. The results obtained in plankton in Yeniça?a Lake showed that aluminum, iron, manganese, zinc, and barium were most accumulated elements in the plankton. The lower averages of lead prevalent in the water and sediment during some months were seen to have a significant mean accumulation in the plankton.     

Spatial distribution and risk assessment of heavy metals in sediments from a hypertrophic plateau lake Dianchi, China

The sediment in Dianchi Lake, a hypereutrophic plateau lake in southwest China, was investigated and the concentration of heavy metals (Cu, Cr, Ni, Zn, Pb, Fe, Mn, and Cd) in the sediment and sediment properties were determined. Their spatial distribution and sources were analyzed using multivariate statistics. The result indicated that the studied metals exhibited three distinct spatial patterns; that is, Cu, Pb, Zn, and Ni had a similar distribution, with a concentration gradient from the north to the south part of the lake; Cd and Cr presented a similar distribution; Fe and Mn presented a quite different distribution than other metals, which indicated their different sources and geochemistry processes. Correlation and cluster analysis (CA) provided origin information on these metals and the CA result was observed corresponding to those three spatial patterns. Principal component analysis further displayed metal source and driving factors; that is, Cu, Pb, Zn, Ni, Cd, and Cr were mainly derived from anthropogenic sources, and Fe and Mn were mainly the result of natural processes. Sediment assessment was conducted using geoaccumulation index (Igeo), potential ecological risk indices, and USEPA guidelines. The result indicated that, generally, Cd was the most serious risk metal; Pb and Cu posed moderate potential ecological risk; Cr, Zn, and Ni had slight ecological risk; Fe and Mn had little risk. Comparison of the assessment tools showed that each of the methods had its limitation and could bias the result, and the combined use of the methodologies and local knowledge on lithology or metal background value of soil in the practice would give a more comprehensive understanding of the metal risk or pollution. Statistical analysis also indicated that nutrients had different impacts on Fe, Mn, and trace elements, which implied that in the assessment of metal risk, nutrients impact should be taken into consideration especially for eutrophic waters.     

Some potential hazardous trace elements contamination and their ecological risk in sediments of western Chaohu Lake, China

The Chaohu is one of the largest five freshwater lakes in China. It provides freshwater for agriculture, life, and part of industry. The quality of water becomes worst and worst due to the toxic matter. In this study, we collected the samples from the sedimentary mud in the lake. The distribution of some potential hazardous trace elements (Cu, Ni, Cr, As, Pb, Cd, and Hg) in the sediments of western Chaohu Lake, has been determined and studied, and the enrichment factors, the index of geoaccumulation, and potential ecological risk were analyzed and calculated. The results show that: the levels of selected potential hazardous trace element vary from different sampling sites and significant anthropogenic impact of Pb and Cd occur in sediments. The contamination rank of Pb and Cd are moderate, and Pb has a light potential ecological risk, but Cd is heavy. The total potential ecological risk of the selected hazardous trace elements in this study in Chaohu Lake is moderate. Cluster and correlation analysis indicate that the selected potential hazardous trace element pollutant has different source and co-contamination also occur in sediments.     

Assessment of seasonal and spatial variations of physicochemical parameters and trace elements along a heavily polluted effluent-dominated stream

This study focuses on a heavily polluted effluent-dominated stream that passes through an industrialized region near Izmir, Turkey. The intermittent creek receives domestic and industrial discharges of Kemalpa?a District Center and its neighborhoods and more than 180 factories of the organized industrial zone. A monitoring campaign was conducted on the creek and samples were taken in two different seasons with distinct hydrological characteristics from 20 stations along the creek to quantify the quality status of water and sediment columns. A number of physicochemical parameters, heavy metals, and trace elements were measured by field and laboratory techniques to assess the status of creek’s water and sediment quality. The spatial and temporal variations were determined, and statistical tools were used to conduct an environmental forensic overview along the creek. A geo-accumulation index and a modified heavy metal pollution index were calculated to cumulatively assess the quality of sediment and water columns, respectively. The results revealed that the creek was under significant pollution load from the industrial zone where metal processing, food and beverage production, marble and natural stone manufacturing, and paper production are made. In particular, elements such as Co, Cu, Cd, Mn, Ni, Pb, Zn, and Zr were found to be above the surface water quality standard values. Similarly, B, Cr, Ni, Cu, Zn, and Sn were determined to be in extreme levels in the sediment column with values exceeding the probable effect concentrations.     

Assessment of heavy metal levels in sediment samples of Kapulukaya Dam Lake (Kirikkale) and lower catchment area

In this study, the concentrations of 13 elements (Al, Fe, Mn, Cr, Ni, Zn, Co, As, Pb, Cu, Mo, Hg, and Cd) were determined in the sediments of three different sites in the Kapulukaya Dam Lake between May 2007 and November 2008. They ranged from 1.47 to 4.64 for Al, 0.92 to 3.48 for Fe (in percent), 326.60 to 1053.00 for Mn, 98.00 to 1,116.00 for Cr, 24.70 to 127.10 for Ni, 14.80 to 124.20 for Zn, 11.0 to 43.20 for Co, 5.00 to 29.30 for Cu, 9.10 to 69.70 for As, 8.60 to 34.00 for Pb, 2.50 to 5.20 for Mo, 1.00 to 1.60 for Hg, and 0.50 to1.80 for Cd in microgram per gram dry weight sediment. The contamination degree of the sediment was assessed on the basis of enrichment factor and corresponding sediment quality guideline. The calculated enrichment factors (EF, measured metal vs. background concentrations) indicated that the effect of man-made activities on the occurrence of concentrations could be accounted for the majority of heavy metals namely Mn, As, Ni, Cu, Zn, Cr, Co, Mo, and Cd, whereas such affect was not detected for Hg and Pb. The maximum values of the EF were represented by As, minimum values by Hg at all sites. Mean EF values were 36.60 and 0.70 for As and Hg, respectively. This study has clearly assessed a certain level of heavy metal pollution in the region, based particularly on the findings from sediment.     

Seasonal Variability of Heavy Metals in Surface Sediment of Lake Sapanca, Turkey

Lake Sapanca is exposed to heavy urbanization and industrialization because of its natural beauty and its proximity to the metropolitan İstanbul, Turkey. In this study, it was aimed to investigate seasonal changes of some heavy metals (Pb, Cr, Cu, Mn, Ni, Zn and Cd) concentration of surface sediment. Nine different stations were chosen as sampling points. Samples were taken every three months and the seasonal and annual average concentration of the elements were determined. Seasonal highest values of heavy metals were observed as follows; Cr, Cu, Mn, Ni and Zn in Summer, Cd in Autumn. There was no seasonal difference for Pb, Cr and Cd. It seems that Lake Sapanca has not been polluted yet. However, it was found that Cu and Ni concentrations in surface sediment exceed lowest effect level.     

Ecological risk assessment of heavy metals in surface sediments of northern littoral zone of Lake Çıldır,Ardahan, Turkey

In this paper, the heavy metal levels (Cu, Pb, Zn, Ni, Mn, Fe, As, Cd, Cr, Hg), organic carbon, and chlorophyll degradation products were studied to prove their ecological effects in Lake Ç?ld?r, where fossil fuels are used as an energy source in the studied area for most of the year, and domestic waste from settlements is discharged directly into the lake. Sediment samples were collected from six sites on the northern shore of Ç?ld?r Lake, Turkey in November 2012. Enrichment (EF) and contamination factor (CF) values were determined, and Pollution Load (PLI) and Potential Ecological Risk (PER) indices were calculated. Average concentrations of heavy metals in the sediments were, in descending order, Fe?>?Mn?>?Zn?>?Ni?>?Cr?>?Cu?>?Pb?>?As?>?Cd?>?Hg, respectively. According to mean values, the source of these elements may be considered natural due to lack of enrichment in Cu, Pb, Zn, Ni, and Cr in the sediment samples. Regarding enrichment of As, Cd, Mn, and Hg, the highest EF belongs to Hg. PLI and PER values indicate there are moderate ecological risk in the lake.     

Contamination assessment of arsenic and heavy metals in a typical abandoned estuary wetland—a case study of the Yellow River Delta Natural Reserve

Coastal and estuarine areas are often polluted by heavy metals that result from industrial production and agricultural activities. In this study, we investigated the concentration trait and vertical pattern of trace elements, such as As, Cd, Ni, Zn, Pb, Cu, and Cr, and the relationship between those trace elements and the soil properties in coastal wetlands using 28 profiles that were surveyed across the Diaokouhe Nature Reserve (DKHNR). The goal of this study is to investigate profile distribution characteristics of heavy metals in different wetland types and their variations with the soil depth to assess heavy metal pollution using pollution indices and to identify the pollution sources using multivariate analysis and sediment quality guidelines. Principal component analysis, cluster analysis, and pollution level indices were applied to evaluate the contamination conditions due to wetland degradation. The findings indicated that the concentration of trace elements decreased with the soil depth, while Cd increases with soil depth. The As concentrations in reed swamps and Suaeda heteroptera surface layers were slightly higher than those in other land use types. All six heavy metals, i.e., Ni, Cu, As, Zn, Cr, and Pb, were strongly associated with PC1 (positive loading) and could reflect the contribution of natural geological sources of metals into the coastal sediments. PC2 is highly associated with Cd and could represent anthropogenic sources of metal pollution. Most of the heavy metals exhibited significant positive correlations with total concentrations; however, no significant correlations were observed between them and the soil salt and soil organic carbon. Soil organic carbon exhibited a positive linear relationship with Cu, Pb, and Zn in the first soil layer (0–20 cm); As, Cr, Cu, Ni, Pb, and Zn in the second layer (20–40 cm); and As, Cr, Cu, Ni, Pb, and Zn in the third layer (40–60 cm). Soil organic carbon exhibited only a negative correlation with Cd (P?I _geo values), which averaged less than 0 in the three soil layers, this finding indicates that the soils have remained unpolluted by these heavy metals. The mean concentrations of these trace elements were lower than Class I criteria. The degradation wetland restoration suggestions have also been provided in such a way as to restore the reserved flow path of the Yellow River. The results that are associated with trace element contamination would be helpful in providing scientific directions to restore wetlands across the world.     

鄱阳湖沉积物重金属空间分布及潜在生态风险评价

通过分析鄱阳湖沉积物重金属空间分布特征,评价其潜在生态风险,并探讨了主要重金属污染来源。结果表明:鄱阳湖沉积物7种重金属元素Cd、Hg、As、Cu、Pb、Cr、Zn含量平均值分别为0.67、0.078、17、51、72、42.9、117 mg/kg,除Cd外,其余6种元素均明显高于相应的背景值。从空间分布来看,Cd、Cr含量总体呈现东南、西北部偏高的现象,而Hg、Cu、Pb含量总体呈现东南部偏高的现象,As、Zn的含量分布相对平均。Hg、Cu、Pb、Zn 4种金属元素之间存在极显著相关性,表明这些元素污染具有同源性。潜在生态风险评价结果显示,单个重金属潜在生态风险顺序为CuHgPbCdAsCrZn;从综合潜在生态风险分析来看,整个湖区的RI值为46.4~476.3,平均值为165.4,属于中等潜在生态危害,其中湖区东南部综合潜在生态风险最高。Cu、Hg、Pb等重金属主要来自乐安河流域工业排放。     

治理后的太湖无锡区域底质中重金属污染现状及生态风险评价

以2005年以后太湖无锡区域底质为研究对象，分析了太湖底泥中重金属的含量分布及富集状况，采用地积累指数法和潜在生态危害指数法对重金属的生态危害进行评价。结果表明：太湖无锡区域底质受重金属轻度污染，含量高于全国水系沉积物平均值；地积累指数法显示太湖无锡区域底质中重金属污染排序为Cu=As〉Pb〉Zn〉Cr〉Cd〉Hg；金属对太湖无锡区域底质构成的潜在生态危害由强到弱为Hg〉Cu〉As〉Cd〉Pb〉Cr〉Zn；从区域上看，2种评价方法均表明底质中重金属危害程度为宜兴沿岸区〉梅梁湖〉五里湖〉贡湖无锡水域。     

贵州某流域城市河段沉积物及悬浮物重金属污染研究

通过在丰水期对贵州省某流域城市河段悬浮物和沉积物中的重金属含量进行测定，运用单因子指数法、生态风险评价法、因子分析法，初步探讨了该河段Cu、Zn、Pb、Hg、Cd、Cr、Ni及As等8种重金属元素的含量分布、污染特征、潜在生态风险及主要来源。检测结果显示，沉积物和悬浮物中Hg、Cd、Zn、Pb、As的平均含量较高，是贵州省土壤背景值的1.02～16.97倍。单因子指数评价结果表明：在沉积物中，Zn、Pb、As为轻度污染，Hg和Cd为重度污染；在悬浮物中，Cu、Pb、As为轻度污染，Zn为中度污染，Hg和Cd为重度污染。潜在生态风险指数评价结果显示，Hg和Cd的生态风险最大，为主要污染元素。研究区沉积物样品综合生态风险指数(RI)介于183.27～1 393.96,平均值为912.06,总体处于严重生态风险等级；悬浮物样品RI值介于341.53～612.38,平均值为436.85,总体处于重度生态风险等级。其中，沉积物样品重金属平均生态风险等级高于悬浮物样品，支流样品重金属生态风险等级总体上低于干流下游样品。根据因子分析法分析结果，初步推测沉积物及悬浮物Hg、Cd、Cr、Ni含量主要受工...     

Risk assessment of trace metals in an extreme environment sediment: shallow,hypersaline, alkaline,and industrial Lake Acıgöl,Denizli, Turkey

The major and trace element component of 48 recent sediment samples in three distinct intervals (0–10, 10–20, and 20–30 cm) from Lake Ac?göl is described to present the current contamination levels and grift structure of detrital and evaporate mineral patterns of these sediments in this extreme saline environment. The spatial and vertical concentrations of major oxides were not uniform in the each subsurface interval. However, similar spatial distribution patterns were observed for some major element couples, due mainly to the detrital and evaporate origin of these elements. A sequential extraction procedure including five distinct steps was also performed to determine the different bonds of trace elements in the <?60-μ particulate size of recent sediments. Eleven trace elements (Ni, Fe, Cd, Pb, Cu, Zn, As, Co, Cr, Al and Mn) in nine surface and subsurface sediment samples were analyzed with chemical partitioning procedures to determine the trace element percentage loads in these different sequential extraction phases. The obtained accuracy values via comparison of the bulk trace metal loads with the total loads of five extraction steps were satisfying for the Ni, Fe, Cd, Zn, and Co. While, bulk analysis results of the Cu, Ni, and V elements have good correlation with total organic matter, organic fraction of sequential extraction characterized by Cu, As, Cd, and Pb. Shallow Lake Ac?göl sediment is characteristic with two different redox layer a) oxic upper level sediments, where trace metals are mobilized, b) reduced subsurface level, where the trace metals are precipitated.     

Contamination and ecological risk assessment of toxic trace elements in the Xi River, an urban river of Shenyang city, China

The objectives of this study were to assess the enrichment, contamination, and ecological risk posed by toxic trace elements in the sediments of the Xi River in the industrialized city of Shenyang, China. Surface sediment and sediment core were collected; analyzed for toxic trace elements; and assessed with an index of geoaccumulation (Igeo), enrichment factor (EF) value, potential ecological risk factor (Er), ecological risk index (RI), and probable effect concentration quotient (PECQ). Elemental concentrations (milligram per kilogram) were 8.5–637.9 for As, 6.5–103.9 for Cd, 12.2–21.9 for Co, 90.6–516.0 for Cr, 258.1–1,791.5 for Cu, 2.6–19.0 for Hg, 70.5–174.5 for Ni, 126.9–1,405.8 for Pb, 3.7–260.0 for Sb, 38.4–100.4 for V, and 503–4,929 for Zn. The Igeo, EF, Er, and PECQ indices showed that the contamination of Cd and Hg was more serious than that of As, Cr, Cu, Ni, Pb, Sb, and Zn, whereas the presence of Co and V might be primarily from natural sources. The Igeo index for Cr and Ni might underestimate the degree of contamination, potentially as a result of high concentrations of these elements in the shale. The RI index was higher than 600, indicating a notably high ecological risk of sediment for the river. The average PECQ for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn ranged from 1.4 to 4.1 for surface sediment and from 5.2 to 9.6 in the sediment cores, indicating a high potential for an adverse biological effect. It was concluded that the sediment in the Xi River was severely contaminated and should be remediated as a hazardous material.     

Fractionation of heavy metals and assessment of contamination of the sediments of Lake Titicaca

Chemical weathering is one of the major geochemical processes that control the mobilization of heavy metals. The present study provides the first report on heavy metal fractionation in sediments (8–156 m) of Lake Titicaca (3,820 m a.s.l.), which is shared by the Republic of Peru and the Plurinational State of Bolivia. Both contents of total Cu, Fe, Ni, Co, Mn, Cd, Pb, and Zn and also the fractionation of these heavy metals associated with four different fractions have been determined following the BCR scheme. The principal component analysis suggests that Co, Ni, and Cd can be attributed to natural sources related to the mineralized geological formations. Moreover, the sources of Cu, Fe, and Mn are effluents and wastes generated from mining activities, while Pb and Zn also suggest that their common source is associated to mining activities. According to the Risk Assessment Code, there is a moderate to high risk related to Zn, Pb, Cd, Mn, Co, and Ni mobilization and/or remobilization from the bottom sediment to the water column. Furthermore, the Geoaccumulation Index and the Enrichment Factor reveal that Zn, Pb, and Cd are enriched in the sediments. The results suggest that the effluents from various traditional mining waste sites in both countries are the main source of heavy metal contamination in the sediments of Lake Titicaca.     

Assessment of heavy metals in sediments from a typical catchment of the Yangtze River, China

An intensive investigation was conducted to study the accumulation, speciation, and distribution of various heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in sediments from the Yangtze River catchment of Wuhan, China. The potential ecological risks posed by these heavy metals also were estimated. The median concentrations of most heavy metals (As, Cd, Cr, Cu, Ni, Pb, and Zn) were higher than the background values of soils in Wuhan and were beyond the threshold effect level (TEL), implying heavy metal contamination of the sediments. Carbonate-bound Cd and exchangeable Cd, both of which had high bioavailability, were 40.2% and 30.5% of the total for Cd, respectively, demonstrating that Cd poses a high ecological risk in the sediments. The coefficients of the relationship among Pb, Hg, and Cu were greater than 0.797 using correlation analysis, indicating the highly positive correlation among these three elements. Besides, total organic carbon content played an important role in determining the behaviors of heavy metals in sediments. Principal component analysis was used to study the distribution and potential origin of heavy metals. The result suggested three principal components controlling their variability in sediments, which accounted for 36.72% (factor 1: Hg, Cu, and Pb), 28.69% (factor 2: Cr, Zn, and Ni), and 19.45% (factor 3: As and Cd) of the total variance. Overall, 75% of the studied sediment samples afforded relatively low potential ecological risk despite the fact that generally higher concentrations of heavy metals relative to TEL were detected in the sediments.     

Speciation of metals in bed sediments and water of Qaraaoun Reservoir, Lebanon

Determination of only total element in sediments does not give an accurate estimate of the likely environmental impacts. Speciation study of metals in sediment provides information on the potential availability of metals (toxic) to biota under various environmental conditions. In water, the toxic metal specie is the free hydrated metal ion. The toxicity of metals depends especially on their chemical forms rather than their total metal content. The present study focuses on Qaraaoun Reservoir, Lebanon. Earlier studies focused only on total metal concentrations in sediment and water. The objective of this study was to determine metal speciation (Fe, Cr, Ni, Zn, Cu, Pb, Cd) in the (operationally defined) sediment chemical fractions and metal speciation in reservoir water. This would reflect on metal bioavailability and toxicity. Water samples and bed sediments were collected from nine sites during the dry season and a sequential chemical fraction scheme was applied to the <75-??m sieve sediment fraction. Metal content in each fraction was determined by the FAAS technique. The data showed that the highest percentages of total metal content in sediment fractions were for: Fe in residual followed by reducible, Cr and Ni in residual and in reducible, Cu in organic followed by exchangeable, Zn in residual and in organic, Pb in organic and carbonate, Cd was mainly in carbonate. Total metal content in water was determined by ICP-MS technique and aqueous metal speciation was predicted using AQUACHEM software interfaced to PHREEQC geochemical computer model. The water speciation data predicted that a high percentage of Pb and Ni were present as carbonate complex species and low percentages as free hydrated ions, highest percentage of Zn as carbonate complex species followed by free hydrated ion, highest percentage of Cd as free hydrated ion followed by carbonate complex species. The sensitivity attempt of free hydrated ion of Ni, Zn, Pb, and Cd in reservoir water revealed dependence of Zn and Cd on pH and alkalinity, while Ni and Pb were only dependent on pH.     

海河干流（市区段）表层沉积物重金属污染及变化趋势分析

根据1990—2006年监测资料,对海河干流（市区段）沉积物中重金属的现状和变化趋势进行了分析,采用地积累指数和Hakanson危害指数对海河干流（市区段）沉积物重金属富集现状和对水生生物危害进行评估。结果显示：海河干流（市区段）表层沉积物除Zn外,均呈现污染下降趋势。海河干流（市区段）沉积物中重金属对生物潜在危害顺序为Cd〉Hg〉As〉Cu〉Pb〉Cr〉Zn,各项指标对生物潜在危害性上游大于下游。     

Metal Pollution Assessment of Sediment and Water in the River Hindon, India

The metal pollution in water and sediment of the River Hindon in western Uttar Pradesh (India) was assessed for Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn. The metal concentrations in water showed wide temporal variation compared with bed sediment because of variability in water discharge and variations in suspended solid loadings. Metal concentrations in bed sediments provided a better evaluation of the degree and the extent of contamination in the aquatic environment, Santagarh and Atali being the most polluted sites of the river. The ratio of heavy metals to conservative elements (Fe, Al, etc.) may reveal the geochemical imbalances due to the elevated metal concentrations normally attributed to anthropogenic sources. Metal/Al ratios for the bed sediments of the river Hindon were used to determine the relative mobility and general trend of relative mobility occurred Fe > Mn > Zn > Cr > Ni > Pb > Cu > Cd.     

某铀尾矿库周围农田土壤重金属污染潜在生态风险评价

为能够定量评价铀尾矿库周围农田土壤重金属污染程度及其潜在生态危害性,采用Hakanson潜在生态风险指数法对土壤中重金属进行综合污染评价。结果表明,铀尾矿库周围部分农田土壤中重金属Cd、Ni、As、Cu、Hg、Zn含量存在积累和超标情况,尤以Cd的污染最严重,Ni、As次之;Pb、Cr含量能够满足标准限值要求。潜在生态风险评价结果显示,铀尾矿库周围农田土壤重金属潜在生态风险较高,主要潜在生态风险因子为Cd,其次是Hg、As,Cr、Pb、Ni、Cu、Zn并不构成潜在生态风险。铀尾矿库周围农田土壤中较高水平的Cd在构成环境污染的同时,也构成了较严重的生态危害,应加强对重金属Cd、Hg的生态风险防治。     

Comparison of leaching tests for the study of trace metals remobilisation in soils and sediments

Several leaching tests were applied and compared to study metal remobilisation on various unpolluted and contaminated soils and on several contaminated sediments. The trace elements considered were Cd, Cr, Cu, Ni, Pb and Zn, and leaching tests consisted of the application of reagents with contrasting characteristics and strengths in order to assess the information provided. An extraction with aqua regia permitted the estimation of the pseudo-total metal content in the sample. Mild extractants such as H2O, CaCl2 and NaNO3 showed low and similar leaching capacities. Acid (CH3COOH) and complexing (EDTA) agents were more effective in remobilising trace metals from soils and sediments. Cd and Zn showed similar extraction characteristics under both extractant solutions, whereas Cu and Pb were more sensitive to complexation, and Ni and Cr to acidification processes. Sequential chemical extractions provided additional information on the association of the trace elements with the different soil and sediment phases. Cd and Zn showed the highest mobility, Pb was associated to reducible solid phases, Cu and Ni to oxidisable phases, and Cr remained mostly in the residual fraction. The results obtained in this paper provided valuable information for choosing a leaching test, which is an instrument of environmental analysis for the estimation of trace metal mobility.