Accumulation and remobilization of metals in superficial sediments in Tianjin, China

The concentrations of Cr, Ni, Cu, Zn, Cd, and Pb in superficial sediment samples collected from three representative sites (Yuqiao Reservoir, Haihe River, and Haihe River Estuary) in Tianjin, North China, were analyzed using various single extraction and sequential extraction procedures to determine their remobilization, extractability, and distribution patterns. Sediments from the Haihe River had higher metal concentrations and geo-accumulation indices, especially for Cd and Zn, than sediments from the other two sites, suggesting that the Haihe River has been heavily influenced by anthropogenic activities. In addition, over 31% and 28.2% of the total Cd in the Haihe River and the Yuqiao Reservoir, respectively, and 18.2% of the total Zn in the Haihe River were found to be associated with the exchangeable form, indicating the significant remobilization of Cd and Zn when compared with Cr and Ni. However, over 98% of the Ni and 78% of the Cr were most closely associated with the residue and oxidizable fractions, which resulted in their becoming environmentally immobile. Based on the Environmental Protection Agency method 3050B, Cd and Zn had the greatest extraction efficiency when a single extraction procedure using 0.5-mol L^???1 HCl, 0.43-mol L^???1 HAcO, and 0.05-mol L^???1 ethylene-diamine-tetra-acetic acid was conducted, with extraction yields of up to 72%, 68%, and 56% for Cd and 50%, 49%, and 29% for Zn, respectively, being obtained for the Haihe River sediments. This was followed by the yields of Cu and Pb and, finally, those of unpolluted metals such as Cr and Ni. HCl and acetic acid extraction provided equivalent information for predicting Cd and Zn mobility in the sediments studied and produced suitable results for quick screening.     

Vertical profile,contamination assessment of mercury and arsenic in sediment cores from typical intertidal zones of China

The vertical profiles, contamination levels, and potential ecological risks of mercury and arsenic were studied from the sediment cores of seven typical intertidal zones, including the Liaohe River Estuary, the Jianhe River Estuary, the Dagu River Estuary, Yancheng Shoal, the Dongtan Yangtze River Estuary, Hangzhou Bay, and the Pearl River Estuary. Marine sediment quality standards, the threshold effect level (TEL), and the probable effect level (PEL) were used as guidelines to evaluate sediment quality. In addition, the geo-accumulation index (I_geo) and potential ecological risk index (\( {E}_r^i \)) were used to assess contamination and potential ecological risks from mercury and arsenic. The results showed that the Pearl River Estuary was moderately polluted by mercury and represented a high potential ecological risk, while other areas were uncontaminated or mildly contaminated with low or moderate potential ecological risks. The Pearl River Estuary was mildly polluted by arsenic and represented a mild potential ecological risk, while other areas were unpolluted and also posed a mild potential ecological risk.     

Biogeochemistry of mercury and methylmercury in sediment cores from Sundarban mangrove wetland, India—a UNESCO World Heritage Site

This study was performed to elucidate the distribution, concentration trend and possible sources of total mercury (Hg(T)) and methylmercury (MeHg) in sediment cores (<63 μm particle size; n?=?75) of Sundarban mangrove wetland, northeastern part of the Bay of Bengal, India. Total mercury was determined by atomic absorption spectrometry (AAS) in a Leco AMA 254 instrument and MeHg by gas chromatography-atomic fluorescence spectrometry (GC-AFS). A wide range of variation in Hg(T) (0.032-0.196 μg g(-1) dry wt.) as well as MeHg (0.04-0.13 ng g(-1) dry wt.) concentrations revealed a slight local contamination. The prevalent low Hg(T) levels in sediments could be explained by sediment transport by the tidal Hugli (Ganges) River that would dilute the Hg(T) values via sediment mixing processes. A broader variation of MeHg proportions (%) were also observed in samples suggesting that other environmental variables such as organic carbon and microbial activity may play a major role in the methylation process. An overall elevated concentration of Hg(T) in surface layers (0-4 cm) of the core is due to remobilization of mercury from deeper sediments. Based on the index of geoaccumulation (I (geo)) and low effects-range (ER-L) values, it is considered that the sediment is less polluted by Hg(T) and there is less ecotoxicological risk. The paper provides the first information of MeHg in sediments from this wetland environment and the authors strongly recommend further examination of Hg(T) fluxes for the development of a detailed coastal MeHg model. This could provide more refine estimates of a total flux into the water column.     

Levels and distribution of PCDD/Fs, dl-PCBs, and organochlorine pesticides in sediments from the lower reaches of the Haihe River basin, China

The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), and organochlorine pesticides (OCPs) in surface sediments from the lower reaches of the Haihe River basin, northern China, were determined by high-resolution gas chromatograph–high-resolution mass spectrometer. The concentrations of 2,3,7,8-substituted PCDD/Fs, dl-PCBs, and total OCPs [sum of hexachlorobenzene, hexachlorocyclohexanes, and dichlorodiphenyltrichloroethane (DDTs)] in 17 sediment samples were in the ranges of 11.6–1,180,924 pg/g dry weight (dw), 18.7–50,017 pg/g dw, and 1.7–35,280 ng/g dw, respectively. The contamination levels in the samples varied significantly between the different sites. Abnormally high concentrations of PCDD/Fs, dl-PCBs, and some OCPs were found in sediments from the lower reaches of the main channel of the Haihe River and the Dagu Drainage River, which were attributed to the historical production of pentachlorophenol and other pesticides near these locations. High levels of DDTs were detected in the Yongding New River sediment, which were likely to have originated from the discharge of wastewater from a dicofol factory upstream. In samples taken from other sites, the concentrations of these pollutants were at levels comparable to those documented in other areas of China. This preliminary investigation suggests that historical pesticide production in the Haihe River basin has contributed significantly to the contamination of this aquatic ecosystem and that further attention to this issue is warranted.     

Occurrence, distribution and bioaccumulation of antibiotics in the Haihe River in China

The occurrence, distribution and bioaccumulation of 22 antibiotics, including eight fluoroquinolones (FQs), nine sulfonamides (SAs) and five macrolides (MLs), in the Haihe River were investigated. Surface water, sediment and fish samples were analyzed by HPLC-MS/MS. Ofloxacin, sulfamethoxazole, sulfadiazine, erythromycin and roxithromycin were found in all surface water samples. SAs were the predominant antibiotics in surface water samples in the mainstream of Haihe River, with the maximum concentration of 201 ng L(-1) for sulfamethoxazole. Compared with Haihe River, higher concentrations of antibiotics were found in the surface water samples in the Dagu and Chentaizi Drainage Rivers. The antibiotics pollution in the mainstream of Haihe River may derive from its tributaries, whereas the wastewater from fish ponds was not the main source of FQs, SAs and MLs in the river water. In sediment samples, FQs were the most frequently detected antibiotics and their concentrations were much higher than SAs and MLs. The high concentrations and detection frequencies of FQs in sediments indicate that sediments are an important reservoir for FQs as they are strongly adsorbed onto sediments. Ciprofloxacin and erythromycin exhibited potential bioaccumulation in crucian carp, with mean bioaccumulation factors of 3262 L kg(-1) and 4492 L kg(-1), respectively.     

Evaluation of metal contamination in sediments from north of Morocco: geochemical and statistical approaches

Concentrations of Fe, Mn, Cr, Cu, Ni, Pb, Zn, Cd and Hg were evaluated in surface sediments of two rivers from north of Morocco, known as Souani and Mghogha rivers. Significantly higher concentrations in mg kg^???1 dry weight (dw) of Mn (747.6 vs. 392.9), Cr (86.4 vs. 56.3), Zn (299.5 vs. 138.5) were found in sediment samples from Mghogha when compared with Souani river. Average concentrations of Cd and Hg in several sediment samples from both rivers were above the effect range median that predicts toxic effects to aquatic organisms. The calculation of enrichment factors showed that Mn, Cr, Cu and Ni were depleted, whereas Pb and Hg were enriched. The results of geoaccumulation index revealed that sediments of both rivers were unpolluted with most of the metals and moderately contaminated with Fe and Hg. Some of elevated concentrations of Hg, principally in Mghogha River, were due to anthropogenic sources including the direct discharges of industrial zone.     

Metal pollution assessment of sediment and water in the Shur River

Intensified industrialization and human activities have resulted in the release of various contaminants into the environment. Among them, heavy metals are often present as a result of mining, milling and industrial manufacturing. In the present investigation, bulk concentrations Pb, Cd, Zn, Cu, Fe, Ca and Al in Shur River (Iran) bed sediments and water around the Sarcheshmeh copper mine were measured from several sample locations. In addition, partitioning was assessed to determine the proportions of metals in different forms. The degree of sediment contamination was evaluated using an Enrichment Factor (EF) and geo-accumulation index (I (geo)) and a newly developed pollution index (I (POLL)). Elevated metals in sediment and water were found to be correlated with areas of the river that were proximal to direct and indirect mining activities. Cadmium and Zn showed the highest pollution index. Cluster analysis was performed in order to assess heavy metal interactions between water and sediment. Chemical partitioning studies revealed that organic metallic bonds were not significantly present in the sediment of the Shur River.     

Assessment and sources of heavy metals in surface sediments of Miyun Reservoir, Beijing

Heavy metals concentrations in surface sediments from Miyun Reservoir were determined to evaluate the pollution and identify the sources. The average content of metals in sediments from Miyun Reservoir followed the order Al>Fe>Ti>Mn>V>Zn>Cr>Ni>Cu>Pb>As>Cd>Hg, and the most mean values were lower than the globe average shale. Heavy metals concentrations at the inflow area of Baihe were higher than those at the inflow area of Chaohe. Heavy metals pollution assessment was carried out by factor enrichment (EF), geoaccumulation index (I _geo), and potential ecological risk (RI). The EF values for all heavy metals except Hg, Cd, and Cr at several sites were lower than 3, suggesting low anthropogenic impact on the metals level. The I _geo values of Pb indicated that half of the sites were unpolluted to moderately polluted and mainly located in the Baihe area of the reservoir. The RI showed that heavy metals of Miyun Reservoir were low potential risk, however, Hg approached or belonged to moderate ecological risk at sites of M5, M7, and M13. Correlation analysis and principal component suggested that Ni, Cu, V, Zn, Mn, Cr, Ti, and Pb were derived from soil erosion in upper reaches of the reservoir, while Fe, Cd, Hg, As, and partial Pb originated from anthropogenic sources, particularly industrial mining and gold tailings.     

Factors affecting food chain transfer of mercury in the vicinity of the Nyanza Site,Sudbury River,Massachusetts

The influence of the Nyanza Chemical Waste Dump Superfund Site on the Sudbury River, Massachusetts, was assessed by analysis of sediment, fish prey organisms, and predator fish from four locations in the river system. Whitehall Reservoir is an impoundment upstream of the site, and Reservoir #2 is an impoundment downstream of the site. Cedar Street is a flowing reach upstream of the site, and Sherman Bridge is a flowing reach downstream of the site. Collections of material for analysis were made three times, in May, July, and October. Sediment was analyzed for acid-volatile sulfide (AVS), simultaneously-extracted (SEM) metals (As, Cd, Cr, Hg, Pb, Sb, Zn), and total recoverable Hg. The dominant predatory fish species collected at all sites, largemouth bass (Micropterussalmoides), was analyzed for the same suite of metals as sediment. Analysis of stomach contents of bass identified smallfish (yellow perch Perca flavescens, bluegill Lepomismacrochirus, and pumpkinseed Lepomis gibbosus), crayfish,and dragonfly larvae as the dominant prey organisms. Samples of the prey were collected from the same locations and at the sametimes as predator fish, and were analyzed for total and methyl mercury. Results of AVS and SEM analyses indicated that sediments were not toxic to aquatic invertebrates at any site. The SEM concentrations of As, Cd, and Cr were significantly higher at Reservoir #2 than at the reference sites, and SEM As and Cdwere significantly higher at Sherman Bridge than at Cedar St. Sediment total Hg was elevated only at Reservoir #2. Hg washigher at site-influenced locations in all fish speciesexcept brown bullhead (Ameiurus nebulosus). Cd washigher in bluegill, black crappie (Pomoxis nigromaculatus),and brown bullhead, and Cr was higher in largemouth bass filletsamples but not in whole-body samples. There were no seasonal differences in sediment or prey organism metals, but some metalsin some fish species did vary over time in an inconsistent manner. Predator fish Hg concentration was significantly linearlyrelated to weighted prey organism methyl Hg concentration. Largemouth bass Hg was significantly lower at Reservoir #2 in our study than in previous investigations in 1989 and 1990. High concentrations of inorganic Hg remain in river sediment asa result of operation of the Nyanza site, and fish Hg concentrations in river reaches downstream of the site areelevated compared to upstream reference sites. However, thedifferences are relatively small and Hg concentrations inlargemouth bass from the site-influenced locations are nohigher than those from some other, nearby uncontaminatedsites. We hypothesize that this results from burial ofcontaminated sediment with cleaner material, which reducesbioavailability of contaminants and possibly reducesmethylation of mercury.     

Elemental composition of sediments in Lake Jinzai, Japan: Assessment of sources and pollution

Bottom sediments from Lake Jinzai in southwest Japan were analyzed to determine their chemical compositions and to assess the potential for ecological harm by comparison with sediment quality guidelines. The pollution status of lake sediments was evaluated by employing contamination factor (CF), pollution load index (PLI), and geoaccumulation index (I(geo)), focusing on a suite of elements in lakebed and core sediments. Elevated concentrations of As, Pb, Zn, Cu, TOC, N, and P were present in several layers of the upper core and other surface sediments. The elevated metal concentrations are likely related to the fine-grained nature of the sediments, reducing bottom conditions produced by abundant organic matter, and possibly minor non-point anthropogenic sources. Moreover, correlations between the concentrations of trace metals and organic carbon, nitrogen, phosphorus, and iron, suggest that these elements play a role in controlling abundances. Calculated CF, PLI, and I(geo) indicate that the sediments are strongly polluted with respect to As, moderately to strongly polluted with Zn, and moderately polluted with Pb and Cu. Metal concentrations exceed the New York State Department of Environmental Conservation (NYSDEC) lowest effect level and the Canadian Council of Ministers of the Environment (CCME) interim sediment quality guidelines that indicate moderate impact on aquatic organisms in the study area.     

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

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

Multivariate analysis for source identification of pollution in sediment of Linggi River,Malaysia

Rapid socioeconomic development in the Linggi River Basin has contributed to the significant increase of pollution discharge into the Linggi River and its adjacent coastal areas. The toxic element contents and distributions in the sediment samples collected along the Linggi River were determined using neutron activation analysis (NAA) and inductively coupled plasma-mass spectrometry (ICP-MS) techniques. The measured mean concentration of As, Cd, Pb, Sb, U, Th and Zn is relatively higher compared to the continental crust value of the respective element. Most of the elements (As, Cr, Fe, Pb, Sb and Zn) exceeded the freshwater sediment quality guideline-threshold effect concentration (FSQG-TEC) value. Downstream stations of the Linggi River showed that As concentrations in sediment exceeded the freshwater sediment quality guideline-probable effect concentration (FSQG-PEC) value. This indicates that the concentration of As will give an adverse effect to the growth of sediment-dwelling organisms. Generally, the Linggi River sediment can be categorised as unpolluted to strongly polluted and unpolluted to strongly to extremely polluted. The correlation matrix of metal-metal relationship, principle component analysis (PCA) and cluster analysis (CA) indicates that the pollution sources of Cu, Ni, Zn, Cd and Pb in sediments of the Linggi River originated from the industry of electronics and electroplating. Elements of As, Cr, Sb and Fe mainly originated from motor-vehicle workshops and metal work, whilst U and Th originated from natural processes such as terrestrial runoff and land erosion.     

Distribution and baseline values of trace elements in the sediment of Var River catchment,southeast France

This study reports on the determination of trace element (TE)—Li, As, Co, Cs, Cu, Pb, U, and Zn—and major element (ME)—Si, Al, Fe, Mg, Ca, Mn, Na, and K—concentrations in 18 riverbed sediments and a sediment core from the Var River catchment using inductively coupled plasma mass spectrometry (ICP-MS). The results were compared with those of a reference sediment core, and the contribution of clay and organic carbon contents in the distribution of TE and ME in the sediment samples was investigated. The mean concentrations of the ME were comparable in both core and riverbed samples and were within the natural averages. In the case of TE, the concentrations were lower in riverbed sediment samples than those found in the sediment core. High mean concentration of As was observed (7.6 μg g^?1) in both core and riverbed sediments, relatively higher than the worldwide reported values. The obtained data indicated that the natural high level of arsenic might be originated from the parent rocks, especially metamorphic rocks surrounding granites and from Permian sediments. Statistical approach, viz., Pearson correlation matrix, was applied to better understand the correlation among TE in both riverbed and sediment core samples. No significant metallic contamination was detected in the low Var valley despite of the localization of several industrial facilities. Therefore, results confirm that the concentrations of the TE obtained in the riverbed sediments could be considered as a baseline guide for future pollution monitoring program.     

A complex investigation of the extent of pollution in sediments of the Sava River. Part 1: Selected elements

The Sava River is the biggest tributary to the Danube River. As a part of the 6th FW EU project, Sava River Basin: Sustainable Use, Management and Protection of Resources (SARIB), ecological status of sediments was investigated. In order to assess the geographical distribution in sediment contamination of the Sava River, inorganic and persistent organic pollutants were analyzed in sediments at 20 selected sampling sites along the Sava River from its spring to its outfall into the Danube River. For comparability of data to other river basins the sediment fraction below 63 μm was studied. Due to complexity of the work performed, the results are published separately (“Part I: Selected elements” and “Part II: Persistent organic pollutants”). In the present study, the extent of pollution was estimated by determination of the total element concentrations and by the identification of the most hazardous highly mobile element fractions and anthropogenic inputs of elements to sediments. To assess the mobile metal fraction extraction in 0.11 mol L^???1, acetic acid was performed (first step of the Community Bureau of Reference extraction procedure), while anthropogenic inputs of elements were estimated on the basis of normalization to aluminum (Al) concentration. According to the Water Framework Directive, the following elements were investigated in sediments: cadmium (Cd), lead (Pb), nickel (Ni), and mercury (Hg). Furthermore, copper (Cu), zinc (Zn), chromium (Cr), arsenic (As), and phosphorous (P) were determined. The analyses of sediments demonstrated slightly elevated values for Hg, Cr, and Ni in industrially exposed sites (concentrations up to 0.6, 380, and 210 mg kg^???1, respectively). However, the latter two elements exist in sparingly soluble forms and therefore do not represent an environmental burden. P concentrations were found in elevated concentrations at agricultural areas and big cities (up to 1,000 mg kg^???1).     

Distribution of mercury and organic matter in particle-size classes in sediments contaminated by a waste water treatment plant: Vidy Bay, Lake Geneva, Switzerland

In Lake Geneva, Switzerland, the most Hg-contaminated sediments have been found in the Vidy Bay where high Hg contents largely exceeds the background levels of Lake Geneva sediments. This contamination has been attributed to the discharge of a waste water treatment plant (WWTP). Total Hg (THg) and monomethylmercury (MMHg) were determined in bulk sediment and in three different grain size fractions (i: clay and silt, ii: fine-coarse sand, iii: and very coarse sand and gravel) collected close to the outlet pipe of a WWTP in order to verify whether the standardized procedures of sediment treatment is adequate for this setting and, by extension, for similar contaminated sites. THg was homogeneously distributed in the different grain size fractions and was correlated to organic matter content (R(2) = 0.6). MMHg was homogeneously distributed in the two finer grain fractions (Φ < 0.063 mm; 0.063 mm < Φ <1 mm). The results of this study suggested that the analysis of the bulk sediment seems to be more appropriate for the assessment of the content and spatial distribution of Hg in freshwater sediments contaminated by WWTPs.     

Assessment of heavy metal contamination in Candarli Gulf sediment, Eastern Aegean Sea

Concentrations of selected heavy metals (Fe, Mn, Ni, Cu, Zn, Pb, Hg, Cr, Al, and As) in surface sediments from 18 stations in the Candarli Gulf were studied in order to understand current metal contamination due to urbanization and economic development in Candarli region, Turkey. The sediment samples were collected by box corer in Candarli Gulf in 2009 to assess heavy metal pollution. Heavy metal concentrations in surface sediment varied from 1.62% to 3.60% for Fe, 0.38?C2.53% for Al, 173?C1,423 for Mn, 8?C100 for Ni, 3?C46 for Cu, 55?C119 for Zn, 16?C138 for Pb, 0.2?C6.3 for Hg, 16?C71 for Cr, and 11?C37 mg kg^???1 for As. This study showed that the concentrations of Mn, Ni, Zn, Pb, Hg, and Cr in the surface sediment layers were elevated when compared with the subsurface layers. Both metal enrichment and contamination factors show that Hg, Zn, and Pb contamination exists in the entire study area and contamination of other metals is also present in some locations depending on the sources.     

Mercury in bottom sediments of the Amur River, its flood-plain lakes and estuary, Eastern Siberia

Mercury (Hg) is an element of a special concern in the Amur River basin, where numerous cinnabar deposits and manifestations have been prospected. Moreover, the territory is under heavy anthropogenic pressure due to intensive economic development that includes activities accompanied by noticeable emissions of Hg to the environment through poor waste management practices and accidental emergency discharges. Yet, information on Hg distribution and behavior in this region is scarce and inadequate. In order to evaluate Hg levels and fate in this vast territory, surveys of river, lake, and estuarine bottom sediments, as integral indicators of environmental status, were carried out in 1990, 1991, 1997, and 2004. The results showed the following: (1) stagnation of the Russian economy in the 1990s has resulted in a noticeable decrease of the Hg content in the Amur River sediments to the basin pristine level of about 0.05 mg kg^???1; (2) Hg distribution in the sediment depth proves the element redox-dependent behavior; (3) in some cases, Hg enrichment may be related to the long-term anthropogenic emission; (4) Hg concentration in bottom sediments was found to increase in the following order—the Amur River mouth, the estuary, and the Sea of Okhotsk, showing the weakly non-conservative Hg behavior during estuarine water mixing.     

贵州煤矿区表层水-沉积物重金属分布特征及来源分析——以新寨河为例

为探索贵州煤矿区表层水-沉积物中重金属的分布特征及来源,科学制定环境保护与污染治理措施,以新寨河为研究对象,在11个样点共采集66个表层水体和沉积物样品,通过对Cd、Pb、Cr、Zn、Cu、As、Hg、Fe、Mn等9种重金属元素进行分析,揭示其在新寨河的空间分布特征。同时,利用多指数法开展了有毒重金属元素污染状况评价,通过相关性分析和主成分分析解析了重金属的来源。结果表明,新寨河流域表层水体中,Fe、Mn点位超标率达100%。表层水中重金属元素的平均含量排序为Fe＞Mn＞Zn＞Cu＞Cr＞As＞Cd＞Pb＞Hg,而沉积物中重金属元素的平均含量排序则是Fe＞Mn＞Zn＞Cr＞Cu＞As＞Pb＞Cd＞Hg,表明新寨河表层水体和沉积物中重金属元素的空间分布存在一定差异。各重金属元素的内梅罗综合污染指数介于0.59~1.13之间,表明新寨河表层水体中重金属的污染程度达到轻微污染水平。单种重金属元素的潜在生态危害系数计算结果显示,90.91%和9.09%的沉积物样点分别被归类为轻微风险和中等风险。所有样点沉积物的潜在生态危害指数介于14.57~120.55之间(均值为72.08),表明新寨河沉积物的潜在生态风险较低。Cu、As在多个样点存在污染现象,需予以重点监控管理。新寨河流域重金属的来源可分为三大类:Cd、Pb、Cr、Zn、Cu为第一类,对应地表径流源;As、Fe、Mn为第二类,对应煤矿开采源;Hg为第三类,对应复合源。     

珠江口黄茅海表层海水和沉积物中重金属的分布及评价

根据2014年4月对珠江口黄茅海海域表层海水和沉积物中重金属分布的调查监测,采用单因子指数法、内梅罗指数法和生态危害指数法对其重金属污染水平进行评价。结果显示:该海域表层海水中部分站位的Pb、Cu、Zn和Hg超出第一类海水水质标准,内梅罗指数评价表明其整体处于轻污染水平。表层沉积物中部分站位的Hg、As和Cu超出第一类海洋沉积物质量标准,内梅罗指数评价表明其整体处于重污染水平,生态危害指数评价表明其整体可能面临中度风险,Hg为主要风险因子。表层海水中Pb、Cu、Zn具有同源性,表层沉积物中Pb、As、Zn和Cu具有同源性。     

Ecosystem Responses to Extreme Natural Events: Impacts of Three Sequential Hurricanes in Fall 1999 on Sediment Quality and Condition of Benthic Fauna in the Neuse River Estuary, North Carolina

A study was conducted in November 1999 to assess sediment quality and condition of benthic fauna in the Neuse River Estuary (NRE), North Carolina, USA, following the passage of three Atlantic hurricanes during the two months prior. Samples for analysis of macroinfauna (>0.5 mm sieve size), chemical contamination of sediments, and other abiotic environmental variables (salinity, dissolved oxygen, pH, depth, sediment granulometry) were collected at 20 sites from the mouth of the Neuse River at Pamlico Sound to approximately 90 km upstream. Results were compared to those obtained from the same area in July 1998 using similar protocols. Depressed salinity, caused by extreme rainfall and associated high freshwater flow, persisted throughout much of the estuary, which had experienced periods of water-column stratification and hypoxia of underlying waters. Fifteen of the 20 sites, representing 299 km² (76% of the survey area), also showed signs of benthic stress based on a multi-metric benthic index of biotic integrity (B-IBI). Benthic impacts included reductions in the abundance, diversity, and numbers of species and shifts in taxonomic composition, with a notable increase in dominance of the opportunistic polychaete Mediomastus ambiseta as other former dominant species declined. There was no significant increase in the extent of chemical contamination compared to pre-hurricane conditions. Storm-related reductions in dissoved oxygen and salinity were the more likely causes of the observed benthic impacts, though it was not possible, based on these results, to separate storm effects from seasonal changes in the benthos and annual episodes of summer anoxia and hypoxia.