Geochemical Distribution of Selected Heavy Metals in Stream Sediments Affected by Tannery Activities

Bayesian regularized back-propagation neural network (BRBPNN) was developed for trend analysis, acidity and chemical composition of precipitation in North Carolina using precipitation chemistry data in NADP. This study included two BRBPNN application problems: (i) the relationship between precipitation acidity (pH) and other ions (NH₄ ⁺, NO₃ ^?, SO₄ ^2?, Ca²⁺, Mg²⁺, K⁺, Cl^? and Na⁺) was performed by BRBPNN and the achieved optimal network structure was 8-15-1. Then the relative importance index, obtained through the sum of square weights between each input neuron and the hidden layer of BRBPNN(8-15-1), indicated that the ions' contribution to the acidity declined in the order of NH₄ ⁺ > SO₄ ^2? > NO₃ ^?; and (ii) investigations were also carried out using BRBPNN with respect to temporal variation of monthly mean NH₄ ⁺, SO₄ ^2? and NO₃ ^? concentrations and their optimal architectures for the 1990–2003 data were 4-6-1, 4-6-1 and 4-4-1, respectively. All the estimated results of the optimal BRBPNNs showed that the relationship between the acidity and other ions or that between NH₄ ⁺, SO₄ ^2?, NO₃ ^? concentrations with regard to precipitation amount and time variable was obviously nonlinear, since in contrast to multiple linear regression (MLR), BRBPNN was clearly better with less error in prediction and of higher correlation coefficients. Meanwhile, results also exhibited that BRBPNN was of automated regularization parameter selection capability and may ensure the excellent fitting and robustness. Thus, this study laid the foundation for the application of BRBPNN in the analysis of acid precipitation.     

武汉市中小河流沉积物重金属污染特征及其生态风险

调查了武汉市9条中小河流表层沉积物中7种重金属的含量及其不同形态组成,并探讨了沉积物重金属污染的来源.研究结果表明,沉积物中7种重金属含量均超过武汉土壤背景值,污染程度中等,其中Cd,Zn和Hg富集严重;基于沉积物质量基准值.Cr,Ni和Zn是沉积物重金属污染生物毒性的主要贡献者;流经武汉市区的罗家渠、府河和巡司河重金属污染急性生物毒性较强.沉积物中不同重金属形态分布迥异,Cd的生物可利用态含量最高,其次为Zn,Ni和Cr,沉积物重金属来源复杂,相关分析和主成分分析表明,Pb和Cd可能主要来源于大气沉降和城市污水,Cr,Zn和Hg来源于金属加工冶炼.而As来源于岩石风化等地球化学过程.     

Spatial and Temporal Variability of Total Non-Residual Heavy Metals Content in Stream Sediments from the Suquia River System,Cordoba, Argentina

The Suquía is a semiarid (rainfall, 700-900 mm y-1), medium-size (7700 km2) riversystem located in central Argentina. Its mountainous upper catchment includes pristine areas aswell as a variety of human settlements and a reservoir lake. A large city (Córdoba, ca. 1.3million inhabitants) and a terminal hypersaline lake are included in the middle and lower basin.Total non-residual (TNR) heavy metals (Pb, Cu, Ni, Zn, Mn, and Fe) have been determined inriver bed sediments in two seasons (spring and autumn), seeking to establish the factors whichcontrol the temporal and spatial variability. The major findings were: a) concentrations of TNRmetals were, in general, higher during springtime than during autumn, particularly downstreamfrom the city of Córdoba; b) organic matter played a significant role as a controlling factorwherever it defined reducing conditions, lowering the concentrations of Mn and Fe hydrousoxides; c) a higher organic load (e.g., downstream the city) and more pronounced reducingconditions could be the causes for the increased Fe concentration, probably precipitated assulfides; d) organic matter exhibited a closer correlation with some TNR metals in autumn,probably caused by a larger capacity for complexation in the biologically-processed organicdebris; and, e) the existence of pristine areas in the drainage basin allowed for the calculation ofenrichment factors (EF) which show the significance of several environmental impacts in theSuquía system.     

Magnetic Signature of Industrial Pollution of Stream Sediments and Correlation with Heavy Metals: Case Study from South France

Industrial pollution is one of the most important environmentalthreats, with serious consequences for the future. Thus, its detailed study is of great importance. Apart from expensive andtime-consuming chemical methods, several rapid and cheap proxymethods have been developed recently, one of them being based on rock-magnetic parameters. In the present paper we examine the use of rock-magnetic methods designed to assess the degree of pollution of recent stream sediments taken from the Arc river (Provence, France). The aim was to identify industrially-derived magnetic particles and to link this `magnetic pollution' to concentrations of heavy metals. Geological basements allow the easy determination of magnetic particles of industrial origin. Our results clearly demonstrate that magnetic anomalies, observed in the stream sediments along the river, can be explained by human activities, as they correlate well with concentrations of lead, zinc, iron and chromium.     

Mobilisation of Heavy Metals in Contaminated Sediments in the River Meuse,The Netherlands

Due to seasonal variation in bottom-water temperature and degradation of organic matter, the depths of the redox boundaries fluctuate in sediments of the river Meuse. This is reflected by a non-steady state behaviour of heavy metals in the surface sediments. Levels of acid-volatile sulphides suggest that dissolved concentrations of heavy metals in the anoxic pore waters are determined by their respective sulphide phases. However, complexation with dissolved organic ligands may significantly increase dissolved concentrations of heavy metals. In most sediments studied, a distinct peak in dissolved concentrations of heavy metals is measured immediately below the sediment-water interface. This concentration peak may be attributed to degradation of organic matter and oxidation of sulphides. Dissolved concentration gradients indicate that upward diffusion of heavy metals from the sediment can contribute to concentrations in the surface water, although significant effects may be confined to specific locations. In addition, it is shown that release of heavy metals as dissolved species to the surface water is negligible compared to particulate-bound fluxes of heavy metals to the sediment.     

Distribution of Heavy Metals in Near-Shore Sediments of the Swan River Estuary,Western Australia

Estuarine systems adjacent to urban areas are at risk of contamination by contaminants from anthropogenic sources, such as heavy metals. We anticipated that the sediments of the Swan River estuary, which runs through metropolitan Perth in Western Australia, would show metal contamination related to industrialization and inputs of stormwater. Total Cu, Pb and Cd concentrations, and Cu, Pb, Cr and Zn inoperationally-defined fractions, were determined inseparate sampling exercises in near-shore sediments ofthe upper Swan River estuary.Total metal concentrations in sediments were not high (maximum values of 297 mg kg^-1 for Cu, 184 mg kg^-1 for Pb and 0.9 mg kg^-1 for Cd) when compared with Australian environmental assessmentguidelines for soils. On the basis of linear regressions between sediment metal concentrations andphysicochemical properties of the sediments (pH, organic carbon, particle size distribution), no single parameter could explain the variation in metal concentrations for all metals. Sediment organic carbon content was positively correlated with Cu concentration; Cu concentrations also increased significantly with increasing clay content anddecreasing sand content. Pb concentrations showed a significant increase with increasing sediment pH, and were approximately three-fold higher in sediments adjacent to stormwater drain outfalls than in sediments remote from drains; no such effect was observed for Cu or Cd. No effect of distance downstream was observed. Sequential extraction of sediments showed that most of the metals were in relatively immobile forms, for example bound to Feoxides, or only extractable by aqua regia. The enhanced concentrations of Pb near stormwater outfalls suggest that vehicle-derived Pb may be an important contributor of Pb to the estuary.     

荣成天鹅湖沉积物中重金属的分布特征研究

通过对表层沉积物中重金属及粒度的分析,研究了荣成天鹅湖重金属的含量水平及分布特征,并对沉积物的环境质量进行了初步评价。结果表明,天鹅湖重金属的总体水平较低,Cd、Cr、Pb、Cu、Zn的平均含量均低于国家海洋沉积物I类质量标准,其中Cr和Pb存在轻度污染。Cd、Cr、Ni、Pb、Cu、Zn的含量范围分别为0～0.84、1.75～116.11、1.50～29.06、17.36～27.25、2.00～34.98mg.kg-1和11.48～92.61mg.kg-1,平均含量排序为Zn〉Cr〉Pb〉Cu、Ni〉Cd。天鹅湖重金属的富集状况与沉积物的粒度以及人类活动密切相关,大部分元素的高值区出现在颗粒较细的湖中央以及污染严重的西北部,东南部含量较低。相关分析表明,各重金属之间的相关性较好,其中Cd、Cu、Mn、Zn、Fe间呈高度的正相关,空间分布规律相似;重金属与有机质、粘粒含量呈极显著正相关,而与砂粒呈极显著负相关。根据加拿大制定的沉积物评价标准,天鹅湖沉积物中Cr具有较大的生态危害性。     

闽江大樟溪下游沿线湿地沉积物中重金属

基于2018年7月采集的大樟溪下游沿线湿地表层沉积物样品,探讨了6种重金属(Pb、Cr、Cu、Zn、Ni、Cd)的沿程分布特征,并运用地累积指数法(Igeo)和潜在生态风险指数法(RI)对其生态风险进行了评估。结果表明,湿地沉积物中重金属的平均含量整体表现为Zn>Pb>Cr>Cu>Ni>Cd,且其沿程变化较为一致,而这主要取决于沉积物粒度组成、磁学参数、pH、EC和有机质的沿程分布。湿地沉积物中的6种重金属含量均于桃花洲、耕櫵亭、方庄村和奥莱时代出现较低值,原因主要与4个采样点的采砂活动改变了河流水沙条件使得沉积物发生粗化有关。湿地沉积物中6种重金属之间均存在极显著正相关关系(P<0.01),说明其具有同源性,并可能代表了一个因采砂/采石活动以及建筑/生活垃圾堆放导致的复合污染源。大樟溪下游沿线湿地大部分样点的Pb处于轻度污染状态,而Cd处于中度污染状态。6种重金属平均单项潜在生态风险指数(E■)表现为Cd>Pb>Ni>Cu>Cr>Zn,Cd具有强生态风险。所有样点重金属的平均RI值为228.62,说明湿地整体处于中等生态风险。研究发现,尽管大樟溪下游沿线湿地沉积物中的重金属含量相比闽江上游其它支流和闽江中下游河段处于一个较低水平,但其Pb、Cd污染及生态风险(特别是Cd)仍较为突出,故下一步在加强对沿线湿地管控时应给予特别重视。     

Heavy Metals in Sediments and Runoff Waters in Soils of the Matanza River Basin,Argentina

Abstract

Soil profiles near watercourses that drain rural areas with agricultural lands and pastures, as well as recreational zones and densely populated industrial centers, are directly influenced by human activities. Therefore, these soils condition the contamination dynamics of the aforementioned watercourses in a remarkable way. The present study deals with soils belonging to a first order subbasin. Pedons representative of positive areas located in slopes (B) and of alkaline sites close to the alluvial plane (T) were selected as study sites. In both cases, the land is used for extensive farming. Composite samples of the upper 5 cm of both soil types were treated either with vermicompost or phosphate fertilizer to study the effect of the addition of these elements on the runoff dynamics of heavy metals. Experiments using a rainfall simulator that formed drops on runoff microplots containing soil samples were carried out under laboratory conditions. The runoff obtained was analyzed for lead (Pb), zinc (Zn), cadmium (Cd), and nickel (Ni), both dissolved and particulate, following the Community Bureau of Reference (BCR) adaptation of the sequential extraction procedure. From these results, it was concluded that the use of high amounts of organic amendment produced important effects on the surface condition of the soils that determine a highly significant reduction in the delivery of suspended solids to watercourses. Amendments, however, may release heavy metals that flow through runoff avenues either as particulate or dissolved forms. Most of the heavy metal concentration is represented by the sediments produced by the runoff and not by the concentration of dissolved elements in runoff waters.     

Distribution of Heavy Metals in Marine Sediments of Palermo Gulf (Sicily, Italy)

Concentrations of Cr, Cu, Hg, Pb and Zn have been measured, by atomic absorption spectrophotometry, in the fine fraction (<63 μm) of surface sediments collected in 30 sites in the Palermo Gulf (Sicily, Italy) in order to assess the levels and the spatial distribution of these elements. Enrichment factors calculated with respect to clean areas have been considered to discriminate between levels due to background or to pollution contributions. The sampling stations, which form a grid inside these areas, are characterized by geographic proximity and by the presence of pollution sources. Ratio matching technique along with hierarchical clustering, minimum spanning tree and principal component analysis have been used for the statistical analysis of data, allowing to better describe the spatial distribution of metal levels. Our work allowed to assess the anthropogenic contribution to the pollution of the area under investigation through industrial and domestic wastes, presence of an harbour area and river inflow.     

Partitioning of Trace Metals in Suspended Sediments from Huanghe and Changjiang Rivers in Eastern China

Assessing metal contamination of sediments requires knowledge of the geochemical partitioning of trace metals at the sediment-water interface. Under controlled laboratory conditions, sequential extraction was conducted to determine the associations of metals (Cd, Cr, and Zn) and radiotracers (¹⁰⁹Cd, ⁵¹Cr, and ⁶⁵Zn) with various geochemical phases and the different partitioning and mobility of metals for two types of surface sediments collected from the Huanghe and Changjiang Rivers in Eastern China. The residual phase was the major phase for stable metal binding, indicating that these sediments had little subjection to recent anthropogenic influences. Fe–Mn oxides were the next important binding phases for metals. The partitioning of metals in various geochemical phases as a function of the duration of the radiolabeling was also examined. Trace metals transferred among the different geochemical phases over the 30 days radiolabeling period, particularly between the carbonate and Fe–Mn oxides phases. The freshwater-sediment distribution coefficients (K _d) of three metals were investigated in batch experiments using the radiotracer technique. The decreasing K _d with increasing metal concentration(from 0.5 to 200 μg L^-1) may be explained by competitive adsorption. The metal K _d in sediments from the Changjiang River was greater than those from the Huanghe River, presumably because of the higher Fe/Mn and organic carbon contents in Changjiang River sediment. The K _d decreased with increasing total suspended solid load from 3 to 500 mg L^-1, and was Cr > Zn > Cd. For Cd and Zn, increasing the pH from 5 to 8 resulted in an increase in K _d due to the reduced H⁺ competition and increasing sorptionpotential. However, the K _d for Cr in the sediments from both rivers showed no relationship with pH, presumably becauseof the complexity of the Cr species and environmental behavior.     

伊通河(长春市区段)沉积物重金属元素化学形态分布特征

对伊通河（长春市区段）沉积物中重金属元素的含量和形态的分布特征进行了研究。结果表明,重金属元素的总量呈现出沿河变化的趋势,且各重金属元素沿河变化程度有很大区别;沉积物中铁主要以残渣态存在,Mn、Pb、Cu、Zn元素残渣态含量很低,而有效态含量却很大（70%）,即伊通河沉积物中存在着潜在的重金属污染。沉积物中重金属在各形态的叠加也有所区别,Pb和Cu主要叠加在有机物态和残渣态中,而Zn则主要叠加在铁锰氧化物态中。     

湿地沉积物重金属环境化学行为研究进展

湿地沉积物重金属污染是当前环境科学领域的研究热点.本文在简要回顾国内外湿地沉积物中重金属污染研究成果的基础上,从湿地沉积物重金属来源、形态组成及提取方法、重金属在沉积物-水界面的迁移转化、质量基准以及风险评价等方面综述了当前国内外研究的最新进展,并提出了该领域未来可能的研究方向.认为针对湿地沉积物重金属向水体释放引起的二次污染问题,应重点对湿地沉积物重金属的环境化学行为展开深入研究,在研究方法和研究手段上应注重新技术的开发与应用.     

Relationships of Heavy Metals in Natural Lake Waters with Physico-chemical Characteristics of Waters and Different Chemical Fractions of Metals in Sediments

The relationships between heavy metal concentrations and physico-chemical properties of natural lake waters and also with chemical fractions of these metals in lake sediments were investigated in seven natural lakes of Kumaun region of Uttarakhand Province of India during 2003–2004 and 2004–2005. The concentrations of Cr, Mn, Fe, Ni, Cu, Zn, Cd and Pb in waters of different lakes ranged from 0.29–2.39, 10.3–38.3, 431–1407, 1.0–6.6, 5.3–12.1, 12.6–166.3, 0.7–2.7 and 3.9–27.1 μg l^?1 and in sediments 14.3–21.5, 90.1–197.5, 5,265–6,428, 17.7–45.9, 13.4–32.0, 40.0–149.2, 11.1–14.6 and 88.9–167.4 μg g^?1, respectively. The concentrations of all metals except Fe in waters were found well below the notified toxic limits. The concentrations of Cr, Mn, Ni, Cu, Zn, Cd and Pb were positively correlated with pH, electrical conductivity, biological oxygen demand, chemical oxygen demand and alkalinity of waters, but negatively correlated with dissolved oxygen. The concentrations of Cr, Ni, Zn, Cd and Pb in waters were positively correlated with water soluble + exchangeable fraction of these metals in lake sediments. The concentrations of Zn, Cd and Pb in waters were positively correlated with carbonate bound fraction of these metals in lake sediments. Except for Ni, Zn and Cd, the concentrations of rest of the heavy metals in waters were positively correlated with organically bound fraction of these metals in lake sediments. The concentrations of Cr, Mn, Ni, Cu and Zn in waters were positively correlated with reducible fraction of these metals in lake sediments. Except for Cd, the concentrations of rest of the metals in waters were positively correlated with residual fraction and total content of these heavy metals in lake sediments.     

Mapping the Distribution of the Bioaccessible Fraction of Trace Metals in the Sediments of an Urban Stream,Park River Watershed,Connecticut

The Park River watershed (PRW), a sub-basin of the Lower Connecticut River watershed, has experienced increased urbanization over the last century as the city of Hartford and its surrounding towns have grown and developed. We present watershed-wide and outflow scale maps of the trace metals Cd, Cu, Zn, and Pb to determine patterns of contamination in fine (<63 μm) stream sediment. Results are compared to established sediment quality guidelines (SQG) and probable effect concentrations (PEC) for each metal. Throughout the watershed, higher concentrations of trace metals are observed in the more urbanized south branch of the PRW. In this sub-basin, there are more industries that use, and waste, metals in their manufacturing processes that contribute to acutely high concentrations of metals in the fine bedload sediments. Impervious surfaces are examined as well in the context of the entire watershed. While an increase in metals can be attributed to an increase in impervious surfaces, these increases do not generally exceed SQGs and PECs. Two focused mapping studies were conducted at the storm water outflow of the West Hartford Landfill and the Trout Brook Sanitary Sewer Overflow (SSO). The purpose of these studies was to analyze the local effects of natural stream features such as channel bar deposits next to the outfalls. We determined that the sediment directly below the two outfalls often exceeded the PEC, while the accumulated sediment around the channel bar deposits was not contaminated beyond background stream levels. We believe mapping at both the small (watershed) and large (outfall) scale can be helpful in future urban studies to determine the extent of trace metal sediment contamination in both channelized and natural sections and may provide a useful method for sediment mitigation endeavors.

     

巢湖表层沉积物中重金属的分布及污染评价

对巢湖湖区不同位点的表层沉积物中的Fe、Cr、Pb、Cu、Co、Zn、Ni7种重金属含量进行的分析表明,湖泊沉积物中重金属含量分布呈现一定的区域特征,由于巢湖西半湖靠近合肥市区,大量的工业废水和生活污水通过河道排入巢湖,引起西半湖区中重金属含量高于东半湖区。采用富集因子法和地积累指数法对巢湖沉积物重金属污染现状进行了评价,结果表明,巢湖沉积物中存在Pb、Cu污染,个别地区已相当严重,并呈现沿湖心区至东半湖区逐渐降低趋势。研究表明,两种方法均能对人为污染行为做出较为科学的评价,且两种方法得到的评价结果基本一致。由于重金属元素有很强的毒性,并且能够在食物链中传递,有关部门应及早从流域环境综合规划入手,对重金属污染问题采取有力的控制对策,保护沿湖地区居民免受危害。此外,对巢湖表层沉积物中重金属污染物来源进行了初步分析,据分析结果判断,巢湖沉积物中重金属总量Co、Fe、Cr的来源相似,Zn和Cu的来源相似。     

巢湖表层沉积物重金属的分布特征及生物有效性

为分析沉积物中重金属的分布特征、相互关系及其可能来源,以安徽巢湖表层沉积物为研究对象,利用原子吸收分光光度法(AAS)测定5种重金属(铅、铜、镍、锌、镉)总量和同步浸提重金属(SEM)含量,同时测定酸可挥发性硫化物、总氮、总磷、总有机碳等多种指标,利用低影响程度(ER-L)和中影响程度(ER-M)基准值,[∑SEM]/[AVS]模型和[∑SEM]-[AVS]模型,判断预测表层沉积物中重金属的生物有效性。结果显示:重金属总量在全湖的空间分布不均匀,具有入湖口大于湖心的特征,共8个指标超过ER-L基准值,西湖区各金属总量大于东湖区,两者之间具有显著性差异(P<0.05),全湖[∑SEM]/[AVS]的值在1.097～2.076之间,但[∑SEM]-[AVS]的变化范围为0.127～0.996μmol/g;表明重金属Cu、Cd污染较严重,人为输入影响大,AVS对重金属的束缚作用有重要影响,大部分表层沉积物中的重金属生物有效性低。     

Distribution of Mercury and Other Heavy Metals in Core Sediments of the Northern Adriatic Sea

Seven sediment cores were collected along a transect about20 km off from the mouth of the Po River, in the northernAdriatic Sea (Italy). Cores were characterised by differentdepositional sequences associated with late Pleistocene-Holocene lowstand (LST), transgressive (TST) and highstand (HST) system tracts. Sediment samples were analysed for mercury, copper, nickel, chromium, manganese and iron, aswell as for total organic matter. Metal distributiongenerally showed vertical and spatial variability ascribed tograin size effects with no significant anthropogenicperturbation. Conversely, mercury showed vertical profilescharacterised by surface enrichment, with concentrations inthe upper layer (50–230 ng g^-1) exceeding 3–11 times the background value of 20 ng g^-1 determined in bottomcores. Surface maxima were attributed to anthropogenic mercurydelivered mainly by the Po River.     

乐清湾滩涂沉积物重金属含量垂向分布及污染评价

在采集乐清湾深度为0—10cm,10—20cm,20—30cm,30—40cm的滩涂沉积物柱状样品基础上,测定了样品中铜、汞、砷、镉、铅、铬和锌等7种重金属含量,以中国海洋沉积物质量标准(GB 18668—2002)所规定的一类沉积物质量为评价标准,利用单因子指数法和沉积物质量基准(sediment quality guideline,SQG)法,对乐清湾滩涂沉积物重金属含量、重金属污染程度及重金属潜在生物毒性风险的垂向分布特征进行分析评价。研究表明,乐清湾滩涂沉积物中铅、锌、镉、铜和铬平均含量随深度增加呈增长趋势,增幅分别达到3.3%,3.3%,18.2%,11.5%和18.6%;汞和砷平均含量则呈下降趋势,下降幅度分别为8.8%和5.1%。对于海水养殖来说,乐清湾不同深度滩涂沉积物均受到铜污染而未受其他6种重金属污染,汞和镉几乎不会引发不利生物毒性效应,铜和砷可偶尔引发不利生物毒性效应,表层滩涂沉积物中铅、锌和铬所偶尔引发的不利生物毒性效应风险低于深层滩涂沉积物。     

Comparison of Various Digestion and Extraction Procedures in Analysis of Heavy Metals in Sediments

Sediment analysis is very important ininvestigations of the heavy metal burden in theenvironment. In the present work various digestion andextraction procedures were evaluated in order toassess the extent of contamination with heavy metalsin sediments from the Moste hydroelectric reservoir.Total acid dissolution, aqua regia digestion andacetic acid extraction procedures were applied tosamples. Zn, Cd, Pb, Co, Ni, Cu and Cr were determinedby flame or electrothermal atomic absorptionspectrometry (FAAS, ETAAS) under optimized measurementconditions. A comparison of total acid dissolutionincluding hydrofluoric acid (HF) treatment and theaqua regia soluble fraction was made to estimatethe applicability of aqua regia digestion inanalysis of total metal concentrations in sediments.In general, good agreement of the results was observedfor Co, Pb, Cu and Zn, however for Cr, Ni and Cdsignificantly lower results were obtained in the aqua regia soluble fraction. In addition, an extraction procedure using 25% v/v acetic acid wasapplied for estimation of the extent of contaminationwith heavy metals originating from anthropogenicactivities. The results indicate that the sedimentsupstream of the reservoir are not contaminated, whilethe sediments from the hydroelectric reservoir showsa significant anthropogenic input of Ni, Zn and Pb,which corresponds well with pollution sources.