Particulate metal speciation in surficial sediments from Loch Dee, southwest Scotland, U.K.

The geochemical partitioning of ten elements in stratified Holocene sediments from Loch Dee, southwest Scotland, has been established by use of a five-stage sequential extraction procedure. Samples from below 15 cm sediment depth show minimal evidence of modification by anthropogenic contamination or active diagenesis and hold Fe, Mg, Cu, Cd, Co, Pb, and Ni primarily in detrital silicates or organic complexes, while Mn, Ca, and Zn reside largely in adsorbed and reducible oxide phases. In the uppermost ca 15 cm of sediment, enhanced total concentrations of Zn, Cu, and Pb reflect increased atmospheric deposition during the postindustrial period. Of these metals, only Pb displays any notable adjustment of partitioning in the enriched zone, showing disproportionate accumulation in labile oxides and organic-Pb phases. The lack of Pb and Zn carbonates in the contaminated horizon may reflect inherent thermodynamic instability under the acid surface and pore-water conditions of Loch Dee. Increments to total Mn and Co in the surficial ca 5 cm of sediment are attributable to the accumulation of secondary oxides and adsorbed species, consistent with precipitation from the interstitial pore-waters across a sedimentary redox front. The presence of metals such as Zn and Cd in soluble or acid-volatile phases in the interfacial sediment has implications for the future management of the Loch Dee basin, with leaching into the overlying waters likely, given the continuation of current trends of lake acidification.     

Trace metal dynamics in a seasonally anoxic lake

Selected results are presented from a detailed 12-month study of trace metals in a seasonally anoxic lake. Dissolved concentrations of Fe, Mn, organic carbon, Cd, Cu, Pb, Zn, and pH were determined in the water column and the interstitial waters on 39 occasions. Trace metal concentrations remained low throughout the year in both water column and pore waters. There was evidence for some remobilization at the sediment-water interface but sediments deeper than 3 cm acted as a sink throughout the year. Variations in the water concentrations were largely associated with increased loading during periods of heavy rainfall. During the summer, concentrations of Cu and Zn in the waters overlying the sediments were enhanced by release from decomposing algal material. Similarly, enhanced concentrations of Cd, Cu, Pb, and Zn were observed during periods of much reduced mixing during ice-cover. Although there were large seasonal variations in the concentrations of dissolved and particulate Fe and Mn, there were no comparable changes in the concentrations of trace metals.     

Mineralogy of metal contaminated estuarine sediments,Derwent estuary,Hobart, Australia: implications for metal mobility

The mobility, bioaccessibility and transfer pathways of metals and metalloids in estuarine sediments have been the focus of much detailed research. However, to date, few studies have examined the mineralogical siting of metals and metalloids in such sediments. This is despite the fact the mineralogy of sediments is an important factor that controls which and how much of a particular metal is released to pore waters and overlying water columns. This study reports on the mineralogical siting of metals in contaminated estuarine sediments, Hobart, Australia, and aims to evaluate the mobility of metals in the contaminated substrates. Mineralogical, mineral chemical and bulk chemical analyses demonstrate that the sediments contain very high levels of several metals and metalloids. The contaminated sediments have concentrations of zinc (Zn), lead (Pb), copper (Cu) and cadmium (Cd) ranging from 0.55 to 4.23 wt%, 0.16 to 0.70 wt%, 415 to 951 mg/kg and 23 to 300 mg/kg, respectively. Franklinite and lesser sphalerite are the main repositories of Zn, whereas much of the Pb and Cu is hosted by sulfides, organic matter and undetermined iron (Fe) oxides. While the release of contaminant loads from franklinite through dissolution is likely to be insignificant, even small releases of metals from the highly contaminated sediments can still cause the deterioration of local water quality. The contaminated sediments represent long-term sources of metal pollutants, particularly Zn, to local waters. This study demonstrates that mineralogical analyses are a vital tool to recognise the potential mobility of trace metals in estuarine environments.     

High spatial resolution sampling of metals in the sediment and water column in Port Jefferson Harbor, New York

Eighteen sediment samples and six water-column samples were collected in a small (6 km²), coastal embayment (Port Jefferson Harbor, New York) to define a high-resolution spatial distribution of metals and to elucidate sources of contaminants to the harbor. Sediment metal (Ag, Cu, Fe, Ni, Pb, V, and Zn) concentrations varied widely, reflecting differences in sediment grain size, with higher metal concentrations located in the fine-grained inner harbor sediments. Calculated enrichment factors for these sediments show that Ag, Pb, Cu, and Zn are elevated relative to both crustal abundances and their respective abundances in sediments in central Long Island Sound. Metal concentrations were 1.2 to 10 fold greater in water from the inner harbor compared to water from Long Island Sound collected outside the mouth of the harbor. Spatial variations in trace metals in surface waters within the bay parallel the spatial variations of trace metals in sediments within the harbor. Elevated water-column metal concentrations appear to be partially derived from a combination of diagenetic remobilization from contaminated sediments (e.g., Ag) and anthropogenic sources (e.g., Cu and Zn) within the southern portions of the harbor. Although the National Status and Trends Program had reported previously that sediment metal concentrations in Port Jefferson Harbor were low, the results of this study show sediment metals have high spatial variability and are enriched in the inner harbor sediments at levels comparable to more urbanized western north shore Long Island harbors.     

Impact of historical metalworks on the concentrations of major and trace elements in sediments: a case study in Finland

The concentrations of major and trace elements were determined (aqua regia leach and ICP-AES analyses) in stream, lake and dredged sediments downstream of the historical Antskog iron- and copperworks, S.Finland. The levels of Ag, Cd, Cu, Pb and Zn are highly elevated in all studied sediment types: roughly half of the studied lake-sediment samples contain >5 ppm Ag, >15 ppm Cd, >0.1% Cu, >0.1% Pb and >0.3% Zn. In the dredged sediment material located onshore, the concentrations of Ag, Cu and Pb are comparable to those in the polluted lake-sediment samples, while in stream sediments elevated metal concentrations are found especially in samples characterised by high concentrations of organic material. The source of the elevated metal concentrations is the historical metalworks at Antskog, mainly the copperworks of the 19th century. Compared to the limit values for contaminated soils in Finland, the concentrations of Cu, Pb and Zn are on average elevated by factors >10 in the polluted horizons of lake sediments, >5 in the dredged sediment located onshore and >2 at the most heavily contaminated site in the stream. Since the surface waters in the area are used for agricultural purposes and for various leisure activities, it is necessary to make further detailed investigations into the extent of the metal pollution and to determine species, mobility and bioavailability of the metals.     

Hydrological and geochemical controls governing the distribution of trace metals in a mine-impacted lake

Factors controlling the distribution of mining-derived Cu, Pb and Zn in the waters and bottom sediments of a large Andean lake (Lago Junin, Peru) have been assessed based on sample collections in May/June 1997 (dry season) and February/March 1998 (wet season). Relatively low levels of trace metals detected in surface waters of the lake during the dry season contrasted greatly with the high values observed during the wet period. Dry season concentrations of total Zn, Cu and Pb in the central lake basin averaged 41, 4.4 and 0.24 µg/L, respectively. In contrast, the respective wet season concentrations of total Zn, Cu and Pb in areas of the main basin ranged up to 387, 52 and 40 µg/L. The seasonal variability in metal concentrations largely reflects an increase in the concentration of particulate metal phases during the wet season. Such observations can be attributed to changes in sediment loadings associated with mining-derived river inputs and changes in lake circulation resulting from hydroelectric dam operations. Surface sediments are characterized by lake-wide enrichments of Zn, Cu and Pb, with maximum concentrations reaching as high as 5, 0.25 and 0.7 wt%, respectively. Estimated rates of authigenic metal accumulation are not sufficient to account for the elevated metal concentrations in the main basin of the lake, indicating that metal distributions are governed by the accumulation of metal-rich particulates. Variations in the spatial distributions of Zn, Cu and Pb are suggested to be a function of varying host phases and textural sorting.     

Major and trace element geochemistry in Zeekoevlei, South Africa: A lacustrine record of present and past processes

This study reports a multi-parameter geochemical investigation in water and sediments of a shallow hyper-eutrophic urban freshwater coastal lake, Zeekoevlei, in South Africa. Zeekoevlei receives a greater fraction of dissolved major and trace elements from natural sources (e.g., chemical weathering and sea salt). Fertilizers, agricultural wastes, raw sewage effluents and road runoff in contrast, constitute the predominant anthropogenic sources, which supply As, Cd, Cu, Pb and Zn in this lake. The overall low dissolved metal load results from negligible industrial pollution, high pH and elevated metal uptake by phytoplankton. However, the surface sediments are highly polluted with Pb, Cd and Zn. Wind-induced sediment resuspension results in increased particulate and dissolved element concentrations in bottom waters. Low C/N ratio (10) indicates primarily an algal source for the sedimentary organic matter. Variation in sedimentary organic C content with depth indicates a change in primary productivity in response to historical events (e.g., seepage from wastewater treatment plant, dredging and urbanization). Primary productivity controls the enrichment of most of the metals in sediments, and elevated productivity with higher accumulation of planktonic debris (and siltation) results in increased element concentration in surface and deeper sediments. Aluminium, Fe and/or Mn oxy-hydroxides, clay minerals and calcareous sediments also play an important role in adsorbing metals in Zeekoevlei sediments.     

Distribution and enrichment of heavy metals in a sediment core from the Pearl River Estuary

A sediment core collected from coastal zone near the Qiao Island in the Pearl River Estuary was analyzed for total metal concentrations, chemical partitioning, and physico-chemical properties. Three vertical distribution patterns of the heavy metals in the sediment core were identified, respectively. The dominant binding phases for Cu, Pb, Cr, and Zn were the residual and Fe/Mn oxides fractions. Cd in all sediments was mainly associated with exchangeable fraction. Influences of total organic carbon content and cation exchange capacity on the total concentrations and fractions of almost all the metals were not evident, whereas sand content might play an important role in the distributions of residual phases of Cr, Cu, Pb, and Zn. In addition, sediment pH had also an important influence on the Fe/Mn oxides, organic/sulfide and residual fractions of Cr, Cu, and Zn. Contamination assessment on the heavy metals in the sediment core adopting Index of Geoaccumulation showed that Cr, V, Be, Se, Sn, and Tl were unpolluted, while Cu, Ni, Pb, Zn, Cd, and Co were polluted in different degrees throughout the core. It was remarkable that the various pollution levels of the metals from moderate (for Cu, Pb, and Zn) to strong (for Cd) were observed in the top 45 cm of the profiles. The relative decrease of the residual fraction in the upper 45 cm of the core is striking, especially for Zn and Cu, and, also for Pb, and Cr. The change in fraction distribution in the upper 45 cm, which is very much contrasting to the one at larger depths, confirms that the residual fraction is related to the natural origin of these metals, whereas in the upper part, the non-residual fractions (mainly the Fe/Mn oxides fraction) are increased due to pollution in the last decade. The possible sources for Cu, Pb, Zn, and Cd contaminations were attributed to the increasing municipal and industrial wastewater discharges, agricultural runoff, atmospheric inputs, and runoff from upstream mining or smelting activities, which may be associated with an accelerating growth of economy in the Pearl River Delta region in the past decade.     

Metal speciation and attenuation in stream waters and sediments contaminated by landfill leachate

The degree of metal contamination (Zn, Pb, Cu, Ni, Cd) has been investigated in the vicinity of an old unmonitored municipal landfill in Prague, Czech Republic, where the leachate is directly drained into a surface stream. The water chemistry was coupled with investigation of the stream sediment (aqua regia extract, sequential extraction, voltammetry of microparticles) and newly formed products (SEM/EDS, XRD). The MINTEQA2 speciation-solubility calculation showed that the metals (Zn, Pb, Cu, Ni) are mainly present as carbonate complexes in leachate-polluted surface waters. These waters were oversaturated with respect to Fe(III) oxyhydroxides, calcite (CaCO₃) and other carbonate phases. Three metal attenuation mechanisms were identified in leachate-polluted surface waters: (i) spontaneous precipitation of metal-bearing calcite exhibiting significant concentrations of trace elements (Fe, Mn, Mg, Sr, Ba, Pb, Zn, Ni); (ii) binding to Fe(III) oxyhydroxides (mainly goethite, FeOOH) (Pb, Zn, Cu, Ni); and (iii) preferential bonding to sediment organic matter (Cu). These processes act as the key scavenging mechanisms and significantly decrease the metal concentrations in leachate-polluted water within 200 m from the direct leachate outflow into the stream. Under the near-neutral conditions governing the sediment/water interface in the landfill environment, metals are strongly bound in the stream sediment and remain relatively immobile.     

Reconnaissance geochemistry of the nechako plateau, British Columbia, using lake sediments

A lake sediment geochemical survey was undertaken over the Nechako plateau, British Columbia, to test application of the technique to regional exploration and compare its effectiveness with results obtained elsewhere. Organic-rich lake sediment samples were collected towards the centre of approximately 500 lakes on a helicopter-assisted survey covering some 16,000 km². Lakes overlying each of five major lithologies contain a distinctive suite of trace metals. Regional variations of Cu, Mo, Pb, Zn, Ni, Cr, Sr, Ba, Ag, Co, V and Ga can be related to differences in underlying geology. In addition, levels of Cu, Mo, Pb and Zn which exceed their regional thresholds are related to mineralization or lithologies favourable to mineralization. Although metal concentrations within a lake may vary up to 12x, anomalous conditions are not masked by this variability and the survey outlined all major sulphide occurrences known in the region.     

Effects of colloids on metal transport in a river receiving acid mine drainage,upper Arkansas River,Colorado, U.S.A.

Inflows of metal-rich, acidic water that drain from mine dumps and tailings piles in the Leadville, Colorado, area enter the non-acidic water in the upper Arkansas River. Hydrous iron oxides precipitate as colloids and move downstream in suspension, particularly downstream from California Gulch, which has been the major source of metal loads. The colloids influence the concentrations of metals dissolved in the water and the concentrations in bed sediments. To determine the role of colloids, samples of water, colloids, and fine-grained bed sediment were obtained at stream-gaging sites on the upper Arkansas River and at the mouths of major tributaries over a 250-km reach. Dissolved and colloidal metal concentrations in the water column were operationally defined using tangential-flow filtration through 0.001-pm membranes to separate the water and the colloids. Surface-extractable and total bed sediment metal concentrations were obtained on the <60-μm fraction of the bed sediment. The highest concentrations of metals in water, colloids, and bed sediments occurred just downstream from California Gulch. Iron dominated the colloid composition, but substantial concentrations of As, Cd, Cu, Mn, Pb, and Zn also occurred in the colloidal solids. The colloidal load decreased by one half in the first 50 km downstream from the mining inflows due to sedimentation of aggregated colloids to the streambed. Nevertheless, a substantial load of colloids was transported through the entire study reach to Pueblo Reservoir. Dissolved metals were dominated by Mn and Zn, and their concentrations remained relatively high throughout the 250-km reach. The composition of extractable and total metals in bed sediment for several kilometers downstream from California Gulch is similar to the composition of the colloids that settle to the bed. Substantial concentrations of Mn and Zn were extractable, which is consistent with sediment-water chemical reaction. Concentrations of Cd, Pb, and Zn in bed sediment clearly result from the influence of mining near Leadville. Concentrations of Fe and Cu in bed sediments are nearly equal to concentrations in colloids for about 10 km downstream from California Gulch. Farther downstream, concentrations of Fe and Cu in tributary sediments mask the signal of mining inflows. These results indicate that colloids indeed influence the occurrence and transport of metals in rivers affected by mining.     

沉积物微量金属元素在重建水体环境变化中的意义

沉积物所记录的微量金属含量与形态的变化是指示人类活动影响下水体环境变化的有效指标,主要用于指示沉积物重金属污染、水体初级生产力变化和氧化还原条件等方面的水体环境状况。总体而言,沉积物中微量金属含量在近一个世纪以来显著上升,反映了采矿、冶金、污水排放、化肥使用、煤炭和石油燃烧等各种人类活动造成水体和沉积物重金属污染的记录作为浮游植物微量营养元素,Cu、Zn、Ni、Ba、Cd等在沉积物中的记录可以指示水体初级生产力水平。U、Mo、V、Cu、Cd、Mn等氧化还原敏感元素在沉积物中的富集或贫化,及其比值(如Re/Mo、Cd/U、Th/U和V/Sc)的变化,是指示水体和沉积物氧化还原环境的有效指标。但需要指出的是,在受人类活动影响的水体中,这些生产力和氧化还原指标很少能指示水体生产力或氧化还原状况,可能主要与人类活动同时造成这些金属元素大量污染输入而掩盖了其自生来源和内在变化的沉积记录有关。所以,对沉积物中微量金属元素来源的判别(陆源碎屑输入、人为输入和水体自生来源)是重建水体环境变化的重要前提。本文总结了多种化学和统计学方法(包括同位素示踪法、化学提取法、富集因子法和主成分分析法等)在沉积物金属来源判别中的应用另外,成岩作用等多种因素会干扰沉积物金属记录对环境变化的指示作用,所以构建多元素指标来综合判断沉积物记录所反映的环境信息是今后的研究所必须关注的     

Heavy metals in sediments of a large, turbid tropical lake affected by anthropogenic discharges

 Bottom-water data and trace metal concentration of Cu, Cr, Ni, Pb, Co, Zn, and organic matter in surficial sediment samples from 13 sampling stations of Lake Chapala in Mexico were studied. The lake is turbid with a great amount of flocculated sediments as a result of wind mixing, sediment re-suspension, and Lerma River discharges. Al distribution pattern in sediments was used as an indicator of the Lerma River discharges into Lake Chapala. The highest values of Cu (33.27 ppm), Cr (81.94 ppm), Pb (99.8 ppm), and Zn (149.7 ppm) were detected in sediments near the lake outlet. The bioavailable metal fraction is low for all metals except Pb, which shows 65–93% of the total metal concentration in bioavailable form. The minimum energy zone in the lake was related to organic matter concentration and was located in the SE part of the lake. An analysis of the studied parameters shows two zones: eastern zone (fluvio-deltaic) and central-western zone (lacustrine). Received: 9 September 1998 · Accepted: 16 November 1998     

Trace metals in sediments near offshore oil exploration and production sites in the Alaskan Arctic

Increased offshore development in the Alaskan Arctic has stimulated interest in assessing potential impacts to the environment before the onset of any adverse effects. Concentrations of trace metals in sediments are used in this paper to provide one sensitive indicator of anthropogenic inputs from offshore activity over the past several decades. Sediments in coastal waters of the western Beaufort Sea are patchy with respect to sediment granulometry, organic carbon content, and concentrations of trace metals. However, results for surface sediments and age-dated cores show that nearly all samples contain natural concentrations of Ag, Ba, Be, Co, Cr, Cu, Hg, Ni, Pb, Sb, Tl, V and Zn, with metal/Al ratios that have been constant for many decades. Metal concentrations for incoming river-suspended matter compare well with sediment metal values and, along with vertical distributions in sediments, show no discernible diagenetic impacts that distort the sedimentary record for metals, except for Mn, As and possibly Cd. Slightly elevated concentrations of Ba, Hg, Ag, Sb and Zn were observed in a total of eight instances or in only 0.7% of the 1,222 data points for metals in surface sediments.     

Environmental geochemistry of El Temsah Lake sediments, Suez Canal district, Egypt

The heavy metal contents of Mn, Ni, Cu, Zn, Cr, Co, Pb, Cd, Fe, and V in the surface sediments from five selected sites of El Temsah Lake was determined by graphite furnace atomic absorption spectrophotometer. Geochemical forms of elements were investigated using four-step sequential chemical extraction procedure in order to identify and evaluate the mobility and the availability of trace metals on lake sediments, in comparison with the total element content. The operationally defined host fractions were: (1) exchangeable/bound to carbonate, (2) bound to Fe/Mn oxide, (3) bound to organic matter/sulfides, and (4) acid-soluble residue. The speciation data reveals that metals Zn, Cd, Pb, Ni, Mn, Cu, Cr, Fe, and V are sink primarily in organic and Fe–Mn oxyhydroxides phases. Co is mainly concentrated in the active phase. This is alarming because the element is enriched in Al Sayadin Lagoon which is still the main site of open fishing in Ismailia. Average concentration of the elements is mostly above the geochemical background and pristine values of the present study. There is a difference on the elemental composition of the sediment collected at the western lagoon (Al Sayadin Lagoon), junction, the shoreline shipyard workshops, and eastern beach of the lake. Depending upon the nature of elements and local pollution source, high concentration of Zn, Pb, and Cu are emitted by industrial wastewater flow (shoreline workshops), while sanitary and agricultural wastewater (El Bahtini and El Mahsama Drains) emit Co and Cd in Al Sayadin Lagoon. On the other hand, there is a marked decrease in potentially toxic heavy metal concentrations in the sediments at the most eastern side of the lake, probably due to the successive sediment dredging and improvements in water purification systems for navigation objective. These result show that El Temsah receives concentrations in anthropogenic metals that risk provoking more or less important disruptions, which are harmful and irreversible on the fauna and flora of this lake and on the whole ecobiological equilibrium.     

Distribution of cadmium, chromium, copper, lead and zinc in marine sediments in Hong Kong waters

Partitioning of heavy metals (Cd, Cr, Cu, Pb, Zn) in marine sediments collected from various sites in Hong Kong waters were determined using sequential extraction method. Sediments from Kellette Bank, located in Victoria Harbour, had higher metal concentrations especially Cu and Zn than most other sites. Slightly over 20% of total Cu and Cr existed as readily available forms in Peng Chau and Kellette Bank. At most sampling sites, over 15% of the Cu existed as the exchangeable form indicating that Cu could be readily released into the aqueous phase from sediments. A significantly higher percentage of Pb and Zn was associated with the three non-residual fractions. Hence, there is a greater environmental concern for remobilization of Pb and Zn compared with Cr. The high amount of residual Cd (>50%) and the relatively lower Cd content indicate that little environmental concern is warranted for the remobilization of Cd. Distribution of metals in sediments collected from different depth at Kellette Bank shows that metal concentrations decreased with profile depth. The levels of Pb and Zn associated with the two readily available fractions increased sharply in the surface sediment. These metals represented the pollutants, which were introduced into the area in the mid-eighties through early nineties as a result of rapid economic and industrial development in the territory. As significant portions of these metals were bound to the readily available phases in the surface sediments, metal remobilization could be a concern. An erratum to this article can be found at     

Mobility and potential bioavailability of traffic-derived trace metals in a ‘wet–dry’ tropical region,Northern Australia

The aqueous mobility and potential bioavailability of metals and metalloids in road runoff in a ‘wet–dry’ tropical location were assessed by analysing metal and metalloid concentrations in particulate, total dissolved and labile dissolved phases in runoff waters. Road-derived Al, Cu, Pb, Sb and Zn concentrations were substantially elevated in runoff when compared to receiving creek waters. Median dissolved concentrations in road runoff exceeded those in creek waters by up to an order of magnitude. Leaching experiments of road sediments confirmed that several metals and metalloids were released in high concentrations from road sediments. Labile Zn and Cu concentrations measured by diffusion gradients in thin films (DGT) showed that almost all dissolved Zn and up to half of dissolved Cu in runoff waters and in road sediment leachate were potentially bioavailable. Comparisons of dissolved metal concentrations in receiving waters affected by road runoff with ecosystem guideline levels, indicated a risk of reaching toxic levels of Cu and Zn in the receiving waters in the absence of adequate treatment or dilution. Low dilution rates of road runoff are likely to occur during late ‘dry’ season/early ‘wet’ season storms which have the potential to produce high metal concentrations derived from long periods of accumulation of road sediment at a time when creek flow rates are at their annual minimum.     

Trace metals (Cd,Pb, Cu,Zn and Ni) in sediment of the submarine pit Dragon ear (Soline Bay,Rogoznica, Croatia)

Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the analyzed metals (Cd: 0.06–0.12 mg kg⁻¹, Pb: 28.5–67.3 mg kg⁻¹, Zn: 17.0-65.4 mg kg⁻¹, Cu: 21.1–51.9 mg kg⁻¹, Ni: 27.8–40.2 mg kg⁻¹) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform. Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate, while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building of the nautical marina) investigated area belonged to unpolluted areas.     

Dissolved trace elements and heavy metals from the shallow lakes in the middle and lower reaches of the Yangtze River region,China

Dissolved trace elements and heavy metals of waters and sediments in the ten shallow lakes in the middle and lower reaches of the Yangtze River region were determined to identify their composition and spatial distribution, and to assess the extent of their environmentally detrimental effects by comparison with water and sediment quality guidelines. Results indicated that As and Pb were the main pollutants in lake waters and Mn and Hg the potential ones, while As, Cu and Pb were the main pollutants in lake sediments. Their spatial distribution indicated that Daye Lake was seriously polluted by metals, which was corroborated by cluster analysis. Higher concentrations of trace elements have been found in lakes downstream of the Yangtze River delta, and higher concentrations of metals have been recorded in sediments of upstream lakes, suggesting that metals in water were more sensitive to anthropogenic activities and that metals in sediment were mainly controlled by minerals. Correlation analyses demonstrated that there were stronger associations among metals in lake sediments than those in lake waters, and their good relationships suggested the common sources. Further research on the subject will help develop water quality management with the aim of restoring shallow lakes in the Yangtze River.     

苏州河沉积物中Zn、Cu 、Hg的形态分布研究及沉积特点初探

本文以上海市苏州河沉积物为研究对象,采用Tessier形态分析法研究了沉积物中重金属元素Zn、Cu和Hg的含量变化与形态分布,初步探讨了沉积特点,对苏州河底泥的进一步治理提供了参考.结果表明,样品中Zn 、Cu、 Hg的含量匀接近或高于生物有影响水平;Zn 、Cu分别主要存在于有机态和Fe-Mn氧化物态中,可交换含量较少;Zn 、Cu、 Hg含量随沉积物浓度的变化为:沉积物表层重金属含量较低并略有起伏,中部较高,底层较低.