Heavy metal pollution and assessment in the tidal flat sediments of Haizhou Bay,China

The heavy metal inventory and the ecological risk of the tidal flat sediments in Haizhou Bay were investigated. Results show that the average concentrations of heavy metals in the surface sediments exceeded the environment background values of Jiangsu Province coastal soil, suggesting that the surface sediments were mainly polluted by heavy metals (Cd, Cr, Cu, Mn, Pb and Zn). In addition, the profiles of heavy metals fluxes can reflect the socio-economic development of Lianyungang City, and heavy metals inputs were attributed to anthropogenic activities. Cr, Cu, Pb and Zn were mainly present in the non-bioavailable residual form in surface sediments, whereas Cd and Mn were predominantly in the highly mobile acid soluble and reducible fractions. The ecological risk of the polluted sediments stemmed mainly from Cd and Pb. According to the Sediment quality guidelines (SQGs), however, the adverse biological effects caused by the heavy metals occasionally occurred in tidal flat.     

云南阳宗海沉积物重金属污染时空特征及潜在生态风险

分析了阳宗海柱状及表层沉积物中Al、Fe、Mn、Zn、Cr、Co、Ni、Cu、As、Cd、Pb等金属元素的含量,结合沉积年代学,研究了沉积物重金属污染的时空变化和潜在生态风险特征.结果表明,表层沉积物中重金属含量具有一定的空间差异性,As、Cd、Cu、Pb和Zn在中东部湖区含量较高,而Cr、Co、Ni含量高值位于南、北湖区的近岸区域;柱状沉积物中,1990s之前As、Cd、Cu、Pb和Zn含量较为稳定,1990s中后期以来,其含量逐渐增加,并在2009-2010年前后达到最大值,此后逐渐下降;而柱状沉积物中Cr、Co、Ni含量变化趋势与Al、Fe相似,总体上由下向上逐渐降低,这主要与沉积物质地(粒度)逐渐变粗有关.重金属富集系数表明,阳宗海沉积物中主要污染元素为As、Cd、Cu、Pb和Zn,1990s中后期污染程度快速增加,2009-2010年前后达到峰值,此后污染程度逐渐降低;表层沉积物中Cu为未污染至"弱"污染水平;Zn、Pb为"弱-中等"污染水平,As为"中等-强"污染水平,Cd为"弱-强"污染水平,中东部湖区污染程度高于其他湖区,这可能与该湖区缺少入湖径流、自然碎屑物质沉积速率较低以及砷污染事件等人为源的重金属贡献影响更为显著有关.生态风险评价结果表明,在2002-2010年前后沉积物重金属达到"中等-强"潜在生态危害,主要贡献因子是Cd和As,近年来其生态风险等级逐渐降低;表层沉积物中重金属在中东部湖区具有"中等"程度潜在生态危害,而其他湖区表层沉积物重金属具有较低程度的潜在生态风险.     

Chemical forms of Pb, Zn and Cu in the sediment profiles of the Pearl River Estuary

The chemical forms of heavy metals (Pb, Zn and Cu) in sediment cores of the Pearl River Estuary were studied using a sequential chemical extraction method. The isotope ratios of 206Pb/207Pb in various chemical fractions were also measured to assess the potential Pb sources. Zinc and Cu were mainly associated with the residual fraction. The Fe-Mn oxide and organic/sulphide fractions were the next important phases for Zn and Cu, respectively. For Pb, different chemical partitioning patterns were found among different sediment cores. Most Pb was associated with the residual fraction in the sediments. In some sediment profiles, the major phase of Pb in the top layers was the Fe-Mn oxide fraction. The proportion of Pb in the Fe-Mn oxide fraction decreased significantly with increasing depth. Among the different depths, the 206Pb/207Pb isotope ratios in the residual fraction remained fairly stable, with a mean value of 1.202, which may represent the natural background value. The 206Pb/207Pb ratios in the exchangeable fraction were the lowest among the five fractions, particularly in top sediments, showing the anthropogenic inputs of heavy metals from recent rapid industrial development in the surrounding region. For the other three non-residual fractions, there was a similar trend of increasing 206Pb/207Pb ratios down the profile. Results from this study are useful in assessing both the chemical changes for heavy metals in marine sediments and the potential of heavy metal release into the water environment of an estuary area.     

Variable influence of the atmospheric flux on the trace metal chemistry of oceanic suspended matter

The particulate concentrations of 17 trace metals, Al, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Ag, Sb, Au, Hg, Pb and Th have been measured in the marine atmosphere (58 samples) and in the deep waters (35 samples) of the Tropical North Atlantic. For oceanic suspended matter, our results are similar to those in samples from the Atlantic and the Pacific Oceans collected during the GEOSECS Program. Based on these results, we have made a flux balance for the mixed layer between input via the atmosphere and removal through small and large particles. These data show that the primary flux of suspended aluminosilicates in the Tropical North Atlantic is attributable to the atmospheric input. Elements Sc, Th, Fe, V, Mn, Co and Cr show high correlation with Al in the marine atmosphere. Of these elements, Fe, Mn, V, Co and Cr are influenced by additional processes such as biological, in the marine environment. For elements Ni, Cu, Zn, Se, Ag, Sb, Au, Hg and Pb, we observe high enrichments (relative to average crustal material) in the marine atmosphere which may be due, at least partially, to the influence of anthropogenic sources. These metals also show similar enrichments in deep ocean suspended matter. Model calculations indicate that the atmospheric flux may not control the deep ocean particulate chemistry of Ni, Cu, Zn, Ag, Sb, Au and Hg. Hence it is likely that, for these elements, the enrichment in the ocean is due to processes within the marine regime, for example their involvement in the biological cycle of the ocean. For Se and Pb, the atmospheric source looks to be the dominant contribution to their particulate concentration in seawater. In the deep North Atlantic, particulate Pb appears to be mostly of anthropogenic origin, which is not the case for Se.     

巢湖沉积物重金属富集特征与人为污染评价

本文分析了巢湖主要入湖河流河口区表层沉积物及西部湖心区沉积岩芯中Al、Fe、Ni、Cr、Cu、Zn、Pb、Li、V等金属元素变化特征,采用地球化学方法对金属元素变化的"粒度效应"进行矫正,并以Li、V为参照元素对矫正结果进行检验;参考历史沉积物,对河口区及西部湖心区沉积物重金属人为污染特征进行分析;结合沉积岩芯210Pb年代结果,估算西部湖心区近150a来Ni、Cr、Cu、Zn、Pb等重金属元素的人为污染贡献量.结果表明,河口表层沉积物重金属污染具有显著的空间差异,南淝河河口重金属人为污染最重,其中Ni、Cr、Cu、Zn、Pb的人为污染贡献量分别为12.2、32.2、25.3、479.9和76.0 mg/kg,分别占总含量的35%、37%、64%、92%和77%;其次是柘皋河河口,主要重金属污染元素为Cu、Zn和Pb,人为污染贡献量达57.6、57.0和19.5 mg/kg,分别占总含量的73%、47%和36%;而派河、白石山河、杭埠河等河口表层沉积物中重金属元素人为污染程度较弱.巢湖西部湖心区主要污染元素为Cu、Zn、Pb,人为污染开始于1950s,1980年以来其人为污染贡献量显著增加,平均为16.2、245.6、47.8 mg/(m2.a),分别占各元素沉积通量的23%、61%和37%;Ni人为污染开始于1980s初期,人为污染贡献量平均为12.6 mg/(m2.a),占其沉积通量的13%左右;Cr基本未受人为污染影响.西部湖心区沉积岩芯及南淝河河口表层沉积物中重金属污染程度均表现为Zn>Pb>Cu,而且南淝河河口沉积物重金属污染程度显著高于西部湖心区.结合主要入湖河流径流量与河口沉积物重金属污染特征,认为巢湖西部湖心区重金属污染主要通过南淝河输入,来自合肥等城市的废水是主要的污染源.     

Trace metal fluxes to nearshore Long Island Sound sediments

Sediments are very important as trace metal ‘sinks’ in coastal areas. In this paper we present data on the concentrations and calculated fluxes of the trace metals, Fe, Mn, Cu, Pb, Zn, Cd and Ag at nearshore sites in Long Island Sound. In both areas a percentage of the metal accumulation can be ascribed to local human activities with the highest anthropogenic metal fluxes occurring closest to their source.     

Anthropogenic metal contamination and sapropel imprints in deep Mediterranean sediments

Sediment cores from the deep Balearic basin and the Cretan Sea provide evidence for the accumulation of Cd, Pd and Zn in the top few centimeters of the abyssal Mediterranean sea-bottom. In both cores, 206Pb/207Pb profiles confirm this anthropogenic impact with less radiogenic imprints toward surface sediments. The similarity between excess 210Pb accumulated in the top core and the 210Pb flux suggests that top core metal inventories reasonably reflect long-term atmospheric deposition to the open Mediterranean. Pb inventory in the western core for the past 100 years represents 20-30% of sediment coastal inventories, suggesting that long-term atmospheric deposition determined from coastal areas has to be used cautiously for mass balance calculations in the open Mediterranean. In the deeper section of both cores, Al normalized trace metal profiles suggest diagenetic remobilization of Fe, Mn, Cu and, to a lesser extent, Pb that likely corresponds to sapropel event S1.     

Detection of anthropogenic Cu, Pb and Zn in continental shelf sediments off Sydney, Australia--a new approach using normalization with cobalt.

Concentrations of Co, Cu, Pb and Zn were determined in 107 surficial sediment samples from the continental margin adjacent to Sydney, Australia. The spatial distributions of trace metals in the sediments and the mud content are similar and increase with greater distance from the coast. In contrast, normalization of the concentrations of Cu, Pb and Zn in the total sediment with Co enables a coastal anthropogenic source to be identified. The spatial distribution of Co-normalized concentrations of Cu, Pb and Zn in total sediment is similar to the distribution of these trace metals in the fine fraction of sediment (<62.5 microm), indicating that Co may be used as a normalizing element for determining contaminant sources in the marine environment near Sydney.     

太湖表层沉积物重金属元素的来源分析

根据太湖MS岩芯重金属元素与Al的线性回归分析及元素/Al、V/Al比率散点图变化规律,讨论了太湖沉积物中重金属元素的来源特征。结果表明:20世纪20年代中期以前,重金属元素主要为自然来源;20年代中期—70年代中期,尽管沉积物中Al、Fe、Zn、Mn、V、Cr等重金属元素含量随沉积物粒度变粗而明显下降,但除Hg受到一定程度的人为污染之外,其它重金属元素仍以自然来源为主,物源有所变化;70年代末期以来,沉积物中重金属元素人为污染逐渐加重,Pb、Cu、Zn、Hg、As等元素既有流域母质来源,又受到一定程度的人为污染。     

Spatial distribution of heavy metals in Hong Kong's marine sediments and their human impacts: a GIS-based chemometric approach

A geographic information system (GIS)-based chemometric approach was applied to investigate the spatial distribution patterns of heavy metals in marine sediments and to identify spatial human impacts on global and local scales. Twelve metals (Zn, V, Ni, Mn, Pb, Cu, Cd, Ba, Hg, Fe, Cr and Al) were surveyed twice annually at 59 sites in Hong Kong from 1998 to 2004. Cluster analysis classified the entire coastal area into three areas on a global scale, representing different pollution levels. Backward discriminant analysis, with 84.5% correct assignments, identified Zn, Pb, Cu, Cd, V, and Fe as significant variables affecting spatial variation on a local scale. Enrichment factors indicated that Cu, Cr, and Zn were derived from human impacts while Al, Ba, Mn, V and Fe originated from rock weathering. Principal component analysis further subdivided human impacts and their affected areas in each area, explaining 87%, 84% and 87% of the total variances, respectively. The primary anthropogenic sources in the three areas were (i) anti-fouling paint and domestic sewage; (ii) surface runoff, wastewater, vehicle emissions and marine transportation; and (iii) ship repainting, dental clinics, electronic/chemical industries and leaded fuel, respectively. Moreover, GIS-based spatial analysis facilitated chemometric methods.     

Anreicherung und Verteilung von Schwermetallen und anderen Elementen in Oberflächensedimenten der Berliner Gewässer und ihres Umlands Enrichment and Distribution of Heavy Metals and Other Elements in Surface Sediments of Berlin Waters (Germany) and their Surroundings

For a wide variety of substances aquatic systems are the medium of origin, or sinks in a longer or shorter lasting stay or even in geological periods. For surface sediments of Berlin waters and their surroundings this paper describes the enrichment and distribution of heavy metals (SM), which have a high priority under international aspects and a marked capability to geoaccumulation. From the 25 metals investigated Hg, Pb, Cu, Cd and Zn are of anthropogenic origin, all others are of geochemical provenience and correspond to background values. Some metals (Hg, Cd, Ni, Co, Cu, Cr and Pb) have specific concentration profiles with increasing depth of water and sediment. The study of correlation of SM in sediments demonstrates generally a strong relation to macroelements and between some metals themselves.     

Geochemical Changes in Metal and Nutrient Loading at Orplands Farm Managed Retreat Site, Essex, UK (April 1995–1997)

Salt marshes have recently been considered to be a major part of the coastal system and have played a key role in the development of the UK coastal management strategy. Managed Retreat (MR) is a process aimed to restore salt marshes by realignment of the seawalls allowing tidal inundation of low value agricultural land. The resultant marshes are expected to function both as an integral part of the flood defence system and as an ecological conservation area. We report on the effects of salt marsh restoration on metal and nutrient loading of the sediment at the Orplands Farm MR site, Essex, UK. Surficial grab and sediment cores were collected from the two fields that comprise the site. The heavy metals, Cd, Cr, Cu, Hg, Pb, Ni and Zn were analysed to determine changes in anthropogenic inputs to sediments. The major ions, Al, Ca, Fe, K, Mg, Mn and Na were also monitored to identify changes in sediment geochemistry. Analysis of the cored sediments after inundation for Na and Sr demonstrated that penetration of estuarine water had, within 2 yr of exposure, reached an average depth of 20 cm. The study observed that input of heavy metals had occurred to the sediments with the most significant being that of Pb, however increases were also observed for Cr and Cu. However, concentrations of Cd in the MR sediments decreased from 1995 to 1997. For the major metals within both fields it was found that the dominant changes were those of enrichment of marine associated metals, Ca, K, Mg and Na via inputs from tidal inundation. The concentration of Ca in the sediments was further enriched by the deposition of carbonates to the sediments. One field demonstrated a significant loss of Fe from sediments which corresponded to changes in redox potential of the sediments. Differences observed in geochemical profiles between the two fields of the site were attributed to differences in land use prior to flooding.     

Lacustrine sediments and lichen transplants: two contrasting and complimentary environmental archives of natural and anthropogenic lead in the South Urals, Russia

Lead (Pb) concentrations and isotope ratios of two different geochemical archives are compared; lake sediment cores and lichens (Hypogymnia physodes, naturally growing and transplanted) from a ca. 80 km-long transect centred on the Cu smelter and former mining town of Karabash, Ural Mountains, Russia. Lead concentrations in sediment cores from 10 lakes were generally low near their base and show an abrupt increase in their upper portions interpreted to coincide with the onset of large-scale smelting operations in 1910. Lead isotope ratios derived from ²⁰⁴Pb, ²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb of the bottom layers differed significantly from those of the top. The top sediments have isotope ratios that show distinct end members, one of which was the stack dust from the Karabash smelter, which is similar to the Pb derived from ores from Sibay, a major mine in the Urals. The composition of the bottom sediment layers generally fall slightly off a mixing line between the top sediments and average Earth’s upper crust. Lichens transplanted from a reference site, as well as naturally growing lichens, sampled from southwest of the smelter have isotope ratios similar to those of the stack dust. Lichens to the northeast contained Pb from the smelter, but are increasingly influenced by other sources probably leaded petrol and local soils, and a signature derived from a source enriched in ²⁰⁷Pb. Vegetables collected from local kitchen gardens contained Pb from an additional atmospheric source, possibly coal. Our work confirms that: (1) Pb isotopes in lake sediments provide a long-term record of inputs and allows the characterisation of natural and anthropogenic sources; (2) Pb isotopes in lichens provide a short-term record of local and long-range atmospheric deposition at high spatial resolution and short time scales as they replace their Pb content within a few months; (3) determination of all four stable Pb isotopes is necessary for the identification of the sources of Pb and is extremely sensitive for discerning minor source signatures, even in an area with a dominant source such as a smelter. Particularly significant for the Karabash area is that ore-smelter-derived airborne Pb is a major component in the lake sediments and lichens but its contribution reaches insignificant levels ca. 40 km from the smelter.     

Redox status and heavy metal risk in intertidal sediments in NW Spain as inferred from the degrees of pyritization of iron and trace elements

Mariculture is an important economic activity in shallow marine areas of the Rías Baixas (Galicia, NW Spain). The maintenance of high product quality requires surveillance of environmental quality, including the risk of metal toxicity. In this study the redox status of intertidal sediments in the Bay of San Simón, and the risk of toxicity posed by their As, Cd, Cr, Cu, Mn, Ni, Pb and Zn contents, were evaluated by determination of operationally defined reactive, silicate-bound, organic and pyrite-related fractions of these elements and of Fe. The large silicate-bound fractions of most of these metals indicate their lithogenic origin; the main exception is Pb, which in all respects exhibits singular behaviour associated with its predominantly anthropogenic origin in a ceramics factory. In sediments with larger fine-grained particle contents, which are oxic only in the top few centimetres, greater proportions of the trace elements are present as sulphides or associated with sulphide minerals: the degree of pyritization of Fe (DOP) is 46% overall, and the pyrite fraction of some elements doubtless increases at the expense of the reactive fraction, most overall degrees of trace metal pyritization (DTMPs) lying in the range 10-50%. A decline in pyrite genesis at depths below about 18 cm in these sediments is attributed to the exhaustion of organic matter susceptible to metabolization by sulphide-generating bacteria. In coarse-grained, oxic sediments the oxidation of sulphides makes pyrite-related fractions very small, and reactive and silicate-bound fractions are negatively correlated; reactive fractions associated with Fe-Mn oxyhydroxides are large, and DOP and DTMPs are low (generally much lower than in mud-rich sediments), except for Pb. Most of the elements studied are mainly present in forms that are neither bioavailable nor potentially bioavailable, and so do not constitute a significant environmental threat. However, the high DTMPs of Cu and Pb indicate significant potential bioavailability, which should be taken into account in evaluations of environmental quality and the risk to bivalve cultures.     

The distribution and speciation of trace metals in surface sediments from the Pearl River Estuary and the Daya Bay, Southern China

Surface sediments collected from the Pearl River Estuary (PRE) and the Daya Bay (DYB) were analyzed for total metal concentrations and chemical phase partitioning. The total concentrations of Cr, Cu, Ni, Pb, and Zn in the PRE were obviously higher than those in DYB. The maximum concentrations of trace metals in DYB occurred in the four sub-basins, especially in Dapeng Cove, while the concentrations of these metals in the western side of the PRE were higher than those in the east side. Such distribution pattern was primarily due to the different hydraulic conditions and inputs of anthropogenic trace metals. The chemical partitioning of metals analyzed by the BCR sequential extraction method showed that Cr, Ni, and Zn of both areas were present dominantly in the residual fraction, while Pb was found mostly in the non-residual fractions. The partitioning of Cu showed a significant difference between the two areas.     

Marine geochronology withPb

The application of²¹⁰Pb dating to an inshore marine deposit off the California coast has been successful. The amounts of unsupported²¹⁰Pb annually accumulated in the Santa Barbara sediments are much greater than those from lake and glacial deposits and than the amount produced through the decay of radium in the overlying water column.     

Variation characteristics of heavy metals and nutrients in the core sediments of Taihu Lake and their pollution history

The sedimentary environment change, trophic evolution and heavy metals pollution history of the northern Taihu Lake in the last 100 years are studied according to the sedimentary geo-chemical proxies of the core sediments, such as grain size, nutrients, heavy metals, diatom, etc. The nutrients in the sediments depended mainly on the lake internal circulation and the heavy metals were from natural geogenic sources before the 1920s, which were not influenced by human activities generally, and grain size was one of the key factors influencing heavy metals content in the sediments. The alternation of manner and strength of human activities in Taihu Lake catchment before and after the 1920s made the lake sediments coarser, and hence heavy metals and TP content decreased contrasted with that before the 1920s. TP content in sediments and water increased from the 1950s to late 1970s due to anthropogenic pollutants discharge, and the lake belonging to mesotrophic state. TN and TOC content and C/N ratio increased due to the increasing external pollutants into Taihu Lake by human activities, TP content also increased obviously in water and sediments, and the diatom association was dominated by eutrophic species since the late 1970s, indicating the eutrophication state of Taihu Lake in this period. Meanwhile the increasing in heavy metals content, such as Cu, Mn, Ni, Pb and Zn, and their proportion of valid fractions in the sediments indicates that they all result from human pollutants since the late 1970s. The heavy metals in the surface sediments have certain potential biological toxicity due to the higher SEM/AVS ratio.     

Variation characteristics of heavy metals and nutrients in the core sediments of Taihu Lake and their pollution history

The sedimentary environment change, trophic evolution and heavy metals pollution history of the northern Taihu Lake in the last 100 years are studied according to the sedimentary geochemical proxies of the core sediments, such as grain size, nutrients, heavy metals, diatom, etc. The nutrients in the sediments depended mainly on the lake internal circulation and the heavy metals were from natural geogenic sources before the 1920s, which were not influenced by human activities generally, and grain size was one of the key factors influencing heavy metals content in the sediments. The alternation of manner and strength of human activities in Taihu Lake catchment before and after the 1920s made the lake sediments coarser, and hence heavy metals and TP content decreased contrasted with that before the 1920s. TP content in sediments and water increased from the 1950s to late 1970s due to anthropogenic pollutants discharge, and the lake belonging to mesotrophic state. TN and TOC content and C/N ratio increased due to the increasing external pollutants into Taihu Lake by human activities, TP content also increased obviously in water and sediments, and the diatom association was dominated by eutrophic species since the late 1970s, indicating the eutrophication state of Taihu Lake in this period. Meanwhile the increasing in heavy metals content, such as Cu, Mn, Ni, Pb and Zn, and their proportion of valid fractions in the sediments indicates that they all result from human pollutants since the late 1970s. The heavy metals in the surface sediments have certain potential biological toxicity due to the higher SEM/AVS ratio.     

Spatial distribution,fractionation and ecological risk assessment of potentially toxic metals in bottom sediments of the Zarivar freshwater Lake (Northwestern Iran)

Freshwater lakes are one of the most vulnerable ecosystems to environmental contamination. This study was initiated to assess the spatial distribution, fractionation, ecological risk of selected potentially toxic metals (Pb, Zn, Cu, Cr, and Ni) in bottom sediments of the Zarivar lake, the second largest freshwater lake in Iran. The results revealed that Pb, Zn and Cu had the high spatial variability (coefficient of variation >50) across the sampling sites and their maximum concentrations (197.5 for Pb, 198.7 for Zn and 185.6 mg/kg for Cu) were observed in sampling sites from the northern, western and eastern margins of the lake. Cr and Ni with average concentrations of 28.3 and 31.38 mg/kg respectively, exhibited low spatial variability (coefficient of variation <20) and their concentrations did not vary significantly among the sampling sites. Based on the redundancy analysis (RDA), sediment organic matter was strongly correlated with Pb, Zn and Cu while Fe₂O₃ and Al₂O₃ showed a positive correlation with Ni and Cr. The calculated average enrichment factor (EF) and geoaccumulation index (I_geo) showed that the contamination level of metals can be arranged in the following order of Pb> Cu > Zn > Cr > Ni. Results from the modified five-step sequential extraction analysis indicated that 40 % of total Pb and Zn were associated with the reducible fraction, 45 % of Cu with the oxidizable fraction and more than 80 % of total Ni and Cr were retrieved from the residual fraction. It was also noticed that Pb, Zn and Cu were more incorporated into the non-residual fractions in the sites with a higher total concentration of these metals, suggesting that both total concentration and fractionation behavior of metals were influenced by their potential sources in the study area. Ecological risk assessment using the potential ecological risk index (PERI) and the modified potential ecological risk index (MPERI) showed that sediments from the eight sampling sites pose a moderate to considerable risk whereas the other sites had low ecological risk level. In comparison to sediment quality guidelines (SQGs), the effects range low (ERL) and probable effect level (PEL) values for Pb, Cu and Zn were exceeded at some sampling sites while Ni and Cr concentrations were found to be below or close to their SQGs values at all the sampling sites. Pb was generally identified as the contaminant of most concern in the study area. Taking into account the results obtained from the fractionation study and the source contribution estimate, it can be inferred that the Pb, Zn and Cu with the average contribution of 79, 54 and 64 % respectively, were mainly derived from anthropogenic sources whereas Ni and Cr with the estimated contribution of 80 and 89 % were predominately from the lithogenic source.     

南京玄武湖底泥重金属形态与环境意义

通过对玄武湖12个底泥样品采用连续提取的方法,分别获得湖中6种金属的总量和形态分布数据,并用因子分析的方法对金属总量进行统计分析.金属总量结果表明,部分样点的Ni和大部分样点的Cr、Pb、Zn超过背景值,显示有轻度污染,这与玄武湖周围的地理环境和人类活动对底泥重金属的影响有关.对金属形态分析的结果表明,在所测金属中残渣态是主要的存在形式,其次比例较高的是有机物和硫化物结合态,而Pb、Zn有潜在的生物危害性.