SEDIMENT POLLUTANTS FROM A RIVER MEANDER REINSTATEMENT SITE : CONCENTRATIONS AND MANAGEMENT IMPLICATIONS

Since European settlement in the early 1800s, 66 artificial meander cut-offs have been created in the lower Latrobe River, Victoria. Contemporary waterway management practices include the reinstatement of a selection of these cut-off meanders to slow water flows and reduce river bed and bank instability. Infill sediments were collected from a range of depths from one of these meanders prior to its reinstatement to estimate the potential for remobilization of any sediment pollutants into the waterway. The characteristics of collected sediments were described and sediments were analysed for a range of pollutants including heavy metals, total petroleum hydrocarbons, monoaromatic hydrocarbons, organochlorine pesticides, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). Metal concentrations in the fine (<63 μm) sediment fraction increased with increasing sample depth; however, only increases in cadmium, chromium and mercury concentrations were statistically significant. Statistically significant increases in mercury concentrations with depth were also present in the entire sediment fraction. With the exception of mercury, concentrations of all metals assessed in meander sediments were similar to those reported as being at background concentrations. Mercury concentrations, although elevated, were below concentrations reported to adversely effect riverine biota. Concentrations of organochlorine pesticides, polychlorinated biphenyls, total petroleum hydrocarbons, monoaromatic hydrocarbons and polycyclic aromatic hydrocarbons were all below detection limits in the entire sediment fraction. As a consequence, reinstatement of the meander as part of a waterway management programme is unlikely to release significant quantities of sediment-partitioned pollutants into the mainstream waterway.     

台州市安溶泾河道底泥重金属污染特征及生态风险评价

为顺利开展城市河道污染整治工程,有效控制河道底泥引发的二次污染,研究河道底泥污染特征并分析其生态风险具有重要意义.基于台州安溶泾河道底泥检测结果,采用单项污染指数法、潜在生态风险指数法、聚类分析法等多种方法对底泥重金属含量、污染状况、空间分布、生态风险等进行评价.结果 表明:底泥中Cu、Zn、Pb、Cd这4种重金属污染...     

水体沉积物重金属质量基准研究综述

沉积物作为重金属污染物的源和汇,对水生环境有着至关重要的影响。如何准确有效的建立沉积物的质量基准已成为当前水环境学的紧迫课题。经过近三十年的发展,沉积物质量基准（Sediment Quality Criteria,SQC）的建立方法有了很大的发展。笔者结合各种文献和国内外最新研究介绍了常用的几种SQC的建立方法,并分析了各种方法的优劣性,最后详细介绍了当前最为流行的两种SQC的建立方法：相平衡分配法和生物效应数据库法。通过对各种方法的比较,对如何建立SQC提出了几点建议,以期为建立适合我国的SQC有所启发。     

广州车陂涌底泥重金属污染及生态风险评价

合理处置重金属污染超标的底泥,是河道清淤工程的重点。以车陂涌清淤工程为例,通过原位测试、化学检验等,掌握河道清淤段不同位置底泥的污染特征。采用潜在生态危害指数法进行底泥污染潜在生态风险评价,得出河涌底泥低风险占31.71%、中等风险占29.27%、较高风险占2.44%、极高风险占36.59%,说明大多底泥需要处理。采用内梅罗综合污染指数法来评价底泥作为农用地土壤的适宜性,73.2%样点属于清洁,尚清洁、轻微污染各占9.8%,中度及严重污染共占7.2%,说明大部分底泥可用于农田。最后提出了该清淤工程应注意的问题,为车陂涌水环境治理提供科学依据。     

拒马河悬浮沉积物对重金属的吸附—解吸研究

研究了拒马河重金属在底质、悬浮物及水体中的分布特性和迁移转化规律 ,经试验得出悬浮物对重金属的吸附与解吸模型。拒马河沉积物对重金属的吸附符合弗兰德利希等温式 ,依据其数学模型计算出吸附与解吸系数 K1 、K2 。探讨了温度、初始浓度、吸附剂浓度对吸附、解吸系数的影响 ,建立起 K值的经验公式 ,将计算值与实验值对照 ,可得到满意的结果     

太子河沉积物重金属污染地积累指数法评价

沿太子河布置34个采样断面,取沉积物样品对其重金属（Cu,Zn,Pb和Cd）含量进行检测和分析,并应用地积累指数法对太子河沉积物重金属污染进行了评价。结果表明：太子河上游断面（本溪市区段和葠窝水库部分断面）沉积物中重金属含量较高;Cd的污染偏重,Cu和Pb其次,Zn无污染;与10年前相比,太子河本溪市区段重金属污染程度有所缓解。     

Assessment of element distribution and heavy metal contamination in Chilika Lake sediments (India)

Chilika Lake is situated on the Indian east coast. It is one of the largest lagoons in the world, with a unique assemblage of marine, brackish water and freshwater species. Due to the opening of new connections to the sea in the years 2000 and 2008, an environmental change is expected in the lagoon. The study gives an assessment of sediment contamination by heavy metals on the verge of this change (sampling campaign in 2000). Sediment samples from two surface levels (0–5 and 30–35 cm), and from depth profiles, were analysed for mineralogical composition, main and trace element concentrations, and element bonding forms. Background concentrations from a depth profile were also examined. The profile spans a time of ≈13 500 years. Age determinations by radiocarbon dating and the ¹³⁷Cs- and ²¹⁰Pb-method were carried out. The composition of the surface sediments is generally uniform. The heavy metals exhibit slightly decreasing concentrations from NE to SW, thus indicating the supply of contaminants from the Mahanadi River. The anthropogenic portion of the heavy metal supply is mainly bound to Fe-oxide-hydroxides. Phosphorus is enriched in the sediments of the southern lake sector. Changes in element concentrations in the last 13 500 years have occurred mainly in two steps. The long-term variations exceed the anthropogenic changes caused by the Mahanadi River inputs. The very sensitive response of coastal area fabrics on climate changes also causes fast geogenic changes in element concentrations in sediments (similar grain sizes). This prevents the use of element concentrations from deep sediment horizons to define contaminations in those areas.     

Chemical characteristics of sediments and interstitial waters in some small Hawkesbury Sandstone freshwater streams of the Sydney area

Sediments of three streams draining sandstone catchments in Sydney, Australia, were sampled under low flow conditions over a 2-year period. Two streams receive urban contaminants, one (the reference creek) has an undeveloped catchment. Levels of sediment copper, zinc, cadmium and lead (total and speciated) and phosphorus (total and organic) were determined, as well as total organic carbon, particle size fractionation and cation exchange capacity. A range of quality parameters were also measured for interstitial waters. Sediments were characterized by very low organic matter (< 2% by weight) and low cation exchange capacity (< 3 mmol Na 100 g⁻¹), due to high contents of coarse and fine sands (> 95%). Despite a low accumulation of heavy metals and phosphorus in the long term, the sediments were nevertheless a sink for these constituents. Greatest proportions of sediment zinc and lead were associated with hydrous metal oxide coatings, or coarse waste particles. Apart from a substantial residual component, copper was preferentially associated with organic matter. Cadmium was rarely detected in any stream. Multidimensional scaling showed that under low flow conditions the three sites had distinct sediment chemistries. However, high levels of temporal and spatial variability were apparent within the urbanized sites, consistent with those streams regularly receiving discharges of diverse composition. Poor sediment and interstitial water qualities were often observed in the two urban sites, although such conditions did not occur continuously. Poor interstitial water quality was also seen on occasion in the reference stream; however, poor sediment quality was never detected at this site. Considering surficial sediments of Hawkesbury Sandstone streams may be suspended during high flow conditions, it was concluded that surface waters were a more reliable indicator of stream condition for short-term monitoring studies.     

Role of bottom sediments in the secondary pollution of aquatic environments by heavy-metal compounds

The results of long‐term investigations into the concentrations of some heavy metals (Fe, Mn, Cu, Zn, Pb, Cr, and Cd) in the bottom sediments of the Dnieper reservoirs and the Dnieper–Bug estuary are considered. Maximum quantities of the metals studied are characteristic of southern water bodies located within industrial zones (the Zaporozh’e and Kakhovka reservoirs as well as the Dnieper–Bug estuary). The highest concentrations of the metals studied occurred in the clay silts (Fe, 11 600–32 400; Mn, 1504–3450; Cu, 38.9–85.5; Zn, 89.8–186.5; Cr, 48.6–193.0; and Cd, 1.9–4.4 mg kg^‐1 dry weight). Accumulation of heavy metals in the bottom sediments is an important factor in the self‐purification of aquatic environments. However, this process is reversible and therefore provides a constant threat of secondary water pollution. Secondary water pollution is observed in summer and autumn when water consumption increases. The concentrations of heavy metals increase by a factor of 1.5–3 after the drawdown of the water level. The main reason for the rise in the concentrations of metals is exchange between the bottom sediments and the water column. The rate of heavy metal migration is connected with the forms of occurrence in solid substrates and pore solutions in the bottom sediments, as well as with physico‐chemical conditions arising at the sediment/water boundary. Therefore, our investigations concentrated on the study of the fractional distribution of heavy metals among solid substrates and their forms of occurrence in interstitial solutions. This distribution depends, most of all, on the chemical properties of metals as well as the chemical and mineralogical composition of the sediments and the chemical properties of pore solutions. Most of the supply of Mn, Zn, Fe, and Cd is associated with oxides and hydroxides of iron and manganese (Mn, 74–93%; Zn, 43–70%; Fe, 27–59%; and Cd, 28–41%). Most copper and chromium is bound to organic matter and to scarcely soluble minerals. In the interstitial solutions studied, metals (except manganese) are found mainly as complex compounds with dissolved organic matter of a different molecular weight. Nevertheless, the fraction of complexes with a relatively low molecular weight (500–5000 Da) prevailed (40–70%). Dissolved manganese in the pore solutions consists chiefly of free (hydrated) ions Mn²⁺ (80–95%). The results obtained were used for a comparative evaluation of heavy metal mobility and the exchange ability of their associated compounds in the bottom sediment–water system.     

黄河干流主要重金属污染特征及其与流量关系

黄河流域重金属污染是水资源利用的一个制约因素。本文利用黄河干流站点1992~1998年实测监测数据,对黄河干流重金属污染变化特征进行初步分析,并分析这些变化与流量之间的内在关系。研究表明,黄河干流重金属在空间和时间上变化比较复杂,没有很明显的规律性。从与流量关系看,非汛期随着流量增加而增加,汛期反而减少。其原因与泥沙(重金属的载体)浓度变化一致。     

Spatial Distributions of Legacy Contaminants in Sediments of Lakes Huron and Superior

The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in order to evaluate the extent of surficial sediment contamination of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons (PAHs), and metals. Sediment concentrations of PCBs, OCs, PAHs, and mercury were generally low and up to 2 orders of magnitude less than in Lakes Erie and Ontario. In contrast, concentrations of metals such as arsenic, copper, and nickel were comparable to those in Lakes Erie and Ontario. These elevated Lakes Superior and Huron metal concentrations were attributed to naturally occurring metals within the bedrock, soil, and sediment of the study region. Concentrations of all contaminants were typically below the Canadian Sediment Quality Probable Effect Level (PEL) guidelines. With regard to spatial patterns, most contaminants were focused primarily in the depositional basins and atmospheric deposition was likely the major source of these chemicals to the lakes. The major exception was for metals (not including mercury) whose patterns were also influenced by natural sources as well as extensive mining activity. A comparison between surficial sediment contamination of samples collected as part of this survey and those collected in the late 1960s/early 1970s using similar methods showed that concentrations of DDT, PCB, lead, and mercury were generally similar between these two time periods. These results are not consistent with production and usage patterns that have declined substantially in the past 3 decades. We hypothesize that the lack of temporal trends is an artifact due to slow sediment accumulation rates as well as differences in analytical protocols between the two time periods.     

Assessing environmental change through chemical-sediment chronologies from inland lakes

This paper examines the hypothesis that the spatial pattern of metal accumulation rates in inland lake sediments provides insight into the causes of the historical and continued loadings of contaminants to the environment. To address this, copper and lead accumulation rates in the Great Lakes' watershed were studied. A multi‐element approach was used, in which many non‐toxic chemicals were measured along with the toxic chemicals of interest, rather than a target‐specific approach. The multi‐element approach also allowed for assessing the environmental state of the lake with respect to its surrounding watershed. Sediment cores were collected from the deepest portion of five Michigan inland lakes, sectioned, metals extracted by nitric acid, microwave digestion and leachates analysed for 26 metals using an inductively coupled, plasma, mass spectrometer with hexapole technology. Sedimentation rates, ages and focusing factors were calculated via ²¹⁰Pb. Dasymetric mapping was used to estimate population distributions in lake watersheds. Watershed area was estimated from digital elevation data using Arc/INFO (ESRI, Redlands, California). The data show that as loadings from dominant (regional) sources decrease (e.g. atmospheric deposition in the case of lead), new patterns provide insight into causes for continued contaminant loadings (e.g. population density). The data also show the universal response of the watersheds to the onset of the anthropogenic loadings of lead but not that of copper. Individual watersheds had different onset times for anthropogenic copper loadings. Recent lead loadings to the environment can be related to population density, and those of copper reflect, in part, a spatial pattern that is similar to the regional pattern for lead during the mid‐1970s. As this pattern for lead could be related to a regional gradient of lead concentrations in atmospheric deposition, the same relation cannot be made for copper. The cause for this spatial pattern for copper is not clear.     

大燕河沉积物重金属污染特征及生态风险分析

为了解大燕河表层沉积物重金属污染特征及潜在生态风险,对大燕河干流和支流沉积物重金属污染物进行了分析,并采用Hakanson生态危害指数法进行评价。结果表明,大燕河干流沉积物重金属含量明显高于支流,重金属含量高于广东省土壤背景值,Cu、Cd、Zn、Pb、Hg超出了土壤环境质量Ⅰ级标准。沉积物中重金属Cu、Cd的富集系数明显高于其他重金属,不同采样点重金属超出背景值的程度具有明显的差异性,呈现干流高于支流,下游高于上游的特征。沉积物中重金属具有极强的生态危害,各种重金属造成的平均生态危害程度由大到小依次为:CdHgCuAsPbZnNiCr,其潜在生态风险应引起足够的重视。     

重金属在黄河中游输送和迁移的水质模拟研究

本文进行了有毒物重金属铅等在黄河中游天然河道中的输送和迁移的水质模拟研究，重点研究了大量泥沙对其运动和归宿影响及水质模型的率定和检验方法，完成了重金属在不同水情期，不同含沙量，泥沙不同冲，淤格局，不同流量下的水质模拟，模拟结果与水体实际监测结果相吻合。     

新疆巩乃斯河水中微量重金属元素的特征分析

对河流中微量重金属元素含量和来源的鉴别是准确、有效控制和预防污染的基本前提。通过对巩乃斯河水样进行分析,初步探讨了河流重金属元素的含量及来源。结果表明:水体中重金属元素Pb、Cr、Cu、Fe等的含量因采样断面的不同而相差悬殊,所测重金属的含量都符合国家地表水环境质量标准中Ⅰ类水标准。通过主成分分析发现河流中金属元素分为2个主要来源:第一主成分为矿物岩石的自然风化、侵蚀过程及工农业排污,其贡献率为63.43%;第二主成分为河流沉积物中金属的迁移、转化,其贡献率为26.11%。其中Pb、Cr、Cu、Fe和Ni主要受第一主成分控制;Mn和Ni主要受第二主成分控制;Cd则是受第一主成分和第二主成分共同支配。     

Distribution,sources, and behavior of trace elements in the Clinton River Watershed,Michigan

The Clinton River watershed near Detroit, Michigan, USA was separated in six different land uses: agricultural, residential, mixed industrial and residential, downstream industrial, Clinton River Spillway, and Lake St. Clair, utilizing As, Cd, Cu, Ni, Pb, and Zn contents of the sediment that has median values of 3, 0.3, 15, 14, 13, and 57 mg kg^− 1, respectively. However, trace element concentrations in the lower Clinton River rivaled those in the most contaminated watersheds of the world. Enrichment factors and principal component analysis (PCA) separated trace elements into 2 categories: anthropogenic (Cd, Cu, Ni, Pb, and Zn) and geogenic (Al, As, Ca, Fe, K, Mg, TOC) sources. PCA linked agricultural, residential, and mixed industrial and residential land uses to anthropogenic Cd, Cu, Ni, Pb, and Zn, and lake sediments to geogenic elements, organic matter and clay contents. The downstream industrial zone has a unique source signature. Trace element concentrations varied with land use. The upper Clinton River (> 20 km from mouth; residential land use; median concentrations up to 25 mg kg^− 1) appeared to meet delisting criteria. Partitioning was also land use and element specific with: (1) exchangeable fraction (up to 94% of total) related to road salt and mobile chloride complex formation; (2) carbonate-bound fraction (up to 100%) resulting from Ca substitution or adsorption; (3) presence of immobile (hydr)oxide-bound fraction (up to 90%) instead of potentially mobile organic matter and sulphide-bound fraction (up to 20%); and (4) residual fraction (up to 65%) originating from geogenic and/or anthropogenic sources.