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.     

Distribution and accumulation of heavy metals in carbonate and reducible fractions of marine sediment from offshore mid-western Taiwan

Two marine sediment cores from offshore mid-western Taiwan were subsampled and pre-treated using a sequential extraction procedure to separate carbonate and reducible fractions. Aliquots of these extracts were analyzed to determine their chemical composition to evaluate the geochemical processes responsible for heavy metal distribution and accumulation in the coastal environment. Our data demonstrate that sedimentation rates derived from excess ²¹⁰Pb associated with metal fluxes show large increases circa A.D. 1990. A well-synchronized increase in metal flux in both geochemical fractions was found and validated by Pearson’s correlation. Principal component analysis revealed the heavy metal fluxes to be highly correlated with the sediment deposition rate, with metal contamination potentially driven by a sole contributor. This study emphasizes the changes in sedimentation rate is potentially caused by activities associated with the inland economic development during this time, rather than by raising heavy metal pollution dominated the accumulation offshore mid-western Taiwan.     

Influence of mangrove reforestation on heavy metal accumulation and speciation in intertidal sediments

To investigate the influence of mangrove reforestation on heavy metal accumulation and speciation in intertidal sediments, core sediments from a restored mangrove forest and adjacent mud flat in Yifeng Estuary (southeastern China) were analyzed. The chemical speciation of heavy metals (Pb, Zn, Cu, Cr and Ni) was determined according to a sequential extraction procedure. Special attention was paid to the upper 20 cm of sediment, in which metal accumulation was enhanced and speciation was obviously modified. Mangrove reforestation decreased the concentrations of all metals in the acid-soluble fraction and increased metal concentrations in the oxidizable fraction. Increased Pb, Zn and Cu concentrations and decreased Ni and Cr concentrations were observed in the reducible fraction. These results suggest that mangrove reforestation facilitated the accumulation of heavy metals in the upper sediment layers but decreased their bioavailability and mobility.     

Distribution and source of heavy metals in the surface sediments from the near-shore area,north Jiangsu Province,China

Samples of surface sediment and vibrocore were collected in the near-shore area of north Jiangsu Province for grain size, elements, ²¹⁰Pb_excess and ¹³⁷Cs analyses. In our study area, the diversity of metal concentration was controlled not by the grain size, but by the source. The element content of the old Yellow River Delta was used as baseline for our study area. Geoaccumulation indexes indicate that no station was polluted by Cu, Pb, Zn and As, but the I_geo values of As were close to zero in some stations. Slight pollution caused by Cd was observed in some stations. Correlation and enrichment factors suggest that Cu, Pb and Zn are lithogenic in origin, while As and Cd are mixed in origin. Especially, in some polluted stations Cd was obviously anthropogenic in origin.     

洞庭湖沉积物中重金属污染特征与评价

于2003-2004年在洞庭湖湖区采集沉积物样品700个,测定了沉积物中As、Cd、Cr、Cu、Hg、Ni、Pb、Zn的含量,并用地积累指数方法和主成分分析法对沉积物中的重金属污染状况进行了评价和分析.结果显示,洞庭湖各子湖区沉积物中Cd、Cr、Cu、Pb、zn的平均含量都属于国家土壤二级标准,AB、Hg、Ni属于国家土壤一级至二级土壤标准;在南洞庭湖与东洞庭湖人湖河流的三角洲的前缘是沉积物重金属积累最高的地点,而在西洞庭湖入湖河流三角洲的后缘沉积物重金属含量比前缘高.采用综合地积累指数法对洞庭湖各子湖区沉积物进行评价,结果表明:南洞庭湖(重污染)>东洞庭湖(偏重污染)>西洞庭湖(中度污染)>大通湖(中度污染)>城陵矶(轻度污染).采用主成分分析法对洞庭湖各子湖区沉积物进行分析,结果表明:南洞庭湖与东洞庭溯第一主成分贡献率分别为55.22%、56.86%,主要支配AS、Cd、Hg、Pb、zn的载荷,而第二主成分贡献率分别为30.04%、33.11%主要支配Cu、Cr、Ni的载荷:西洞庭湖、大通湖和城陵矶因沉积物重金属来源不同,主成分分析结果相差较大.     

Distribution and ecological risk assessment of some heavy metals in coastal surface sediments along the Red Sea,Egypt

The ecological risk assessment for Al,Zn,Cu,Ni,V,Pb,Cd,and Hg in surface sediment collected from the Egyptian Red Sea coast was evaluated using the Geo-accumulation Index(I_(geo)).Sediment Enrichment Factor(SEF) and Potential Ecological Risk Index(PERI) methods.The predominant heavy metal,aluminum,showed high concentrations along both of Aqaba Gulf(4378.8 ± 2554.1 μg/g) and southern part of the Red Sea(2972.8 + 1527.5 μg/g).while it recorded the lowest concentration in Suez Gulf(829.7 ± 398.2 μg/g).The determined heavy metal concentrations had the order of Al Zn -Ni V Pb Cu Cd Hg.The statistical analyses showed some correlations among the heavy metals contents.Several international sediment quality guidelines were used to estimate the quality of the collected sediments.Interestingly,the recorded average heavy metals concentrations were lower than those of the permissible contents for sediment quality guidelines.The Geo-accumulation index calculations(I_(geo)) proved that the investigated region could be classified as an unpolluted area.Sediment Enrichment Factor(K_(SEF)) study showed high values in Suez Gulf region.The single pollution index analysis of heavy metals in the sediments(C~i_f) indicated that Al,Zn,V,and Pb were of natural origin,while Ni,Cd and Hg were seriously affected by human activities.Interestingly,amongst,all the determined heavy metals,Cd and Hg gave moderate ecological risk indicators.     

Toxicological impact assessment of heavy metal contamination on macrobenthic communities in southern coastal sediments of Korea

In the heavily industrialized Masan Bay of southern coast, Korea, the potential harmful effects of heavy metals (Cd, Co, Cu, Ni, Pb, Sn, Zn, and Hg) were evaluated in terms of the pollution load index (PLI) and ecological risk assessment index (ERI) methods, and the results obtained were considered alongside the health of the macrobenthic fauna communities. The results revealed that the bay sediments, especially in the inner bay and the outfall area of a sewage treatment plant, are exposed to moderate to serious levels of metal pollution. Hg and Cd contributed the most to the potential toxicity response indices in sediments recently deposited in the bay. The potential ecological risk assessment of heavy metals in the bay was highlighted by the use of the benthic biological pollution index (BPI), suggesting that the ERI is a useful toxicity response index, which can quantify the overall ecological risk level to a target environment.     

Distribution and pollution assessment of heavy metals in surface sediments in the Yellow Sea

Heavy metal concentrations in surface sediments at 56 stations during two cruises in the Yellow Sea in summer and winter, 2011 were analyzed by inductively coupled plasma-mass spectrometry. The pollution status was assessed via the Geoaccumulation index and Hankanson potential ecological risk index. Higher concentrations of heavy metals (except for Mn) were found in the central Southern Yellow Sea and the western Northern Yellow Sea. The higher contents of Mn were much closer to Shandong Peninsula. Correlation analyses indicated that Pb, Cu, Fe, Ni, Zn and Co probably had the same origin and were controlled by grain size and total organic carbon. Pollution assessment showed that most areas of the Yellow Sea were not or lowly contaminated with the exception of the northwest and south parts of the Southern Yellow Sea showing Cd-contamination. The pollution status of the Yellow Sea in summer was worse than that in winter.     

Total petroleum hydrocarbons and heavy metals in the surface sediments of Bohai Bay,China: Long-term variations in pollution status and adverse biological risk

Surface sediments collected from 2001 to 2011 were analyzed for total petroleum hydrocarbons (TPH) and five heavy metals. The sediment concentration ranges of TPH, Zn, Cu, Pb, Cd and Hg were 6.3–535 μg/g, 58–332 μg/g, 7.2–63 μg/g, 4.3–138 μg/g, 0–0.98 μg/g, and 0.10–0.68 μg/g, respectively. These results met the highest marine sediment quality standards in China, indicating that the sediment was fairly clean. However, based on the effects range-median (ERM) quotient method, the calculated values for all of the sampling sites were higher than 0.10, suggesting that there was a potential adverse biological risk in Bohai Bay. According to the calculated results, the biological risk decreased from 2001 to 2007 and increased afterwards. High-risk sites were mainly distributed along the coast. This study suggests that anthropogenic influences might be responsible for the potential risk of adverse biological effects from TPH and heavy metals in Bohai Bay.     

Anthropogenic influences on heavy metals across marine habitats in the western coast of Venezuela

Concentrations of ten metals were measured in waters and sediments at 14 sites during four sampling periods (1996–1997). These sites include various marine ecosystems that are highly influenced by industry, tourism and river discharges, nine of which are within the Morrocoy National Park. Spatially, metal concentrations in water were homogenous, whereas in sediments their distributions were related to grain size. Maximum concentrations of cadmium (Cd) and mean concentrations of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) in water were above the guideline values proposed by NOAA, indicating the potential of these metals for producing chronic effects in marine biota. Sheltered sites showed the highest metal concentrations in sediments; with Cd and Zn above these guidelines. Enrichment factors and geo-accumulation indexes suggested that metals in sediments were largely of natural origin except for Pb, Cd and vanadium (V), which were apparently associated with industrial effluents. A disruption of the spatial distribution of metals after heavy rainfall, when exposed sites reached concentrations as high as those in sheltered sites, showed the influence of nearby rivers. The potential increase of such climatic events could represent additional stress for natural protected areas in the Caribbean.     

Assessment of metal contamination in surface sediments from Zhelin Bay,the South China Sea

Metals and biogenic elements were analyzed from surface sediments collected from Zhelin Bay in the South China Sea in December 2008. The high concentrations of TOC, TN and BSi indicate the high nutrient level and diatom productivity in Zhelin Bay. The concentrations of metals were generally far lower than the effects-range-low (ERL) values that define pollutant levels. Enrichment factors (EF) and geoaccumulation indices (I_geo) suggest there are pollution levels of Cd, Cu and Zn at some stations. As, Cu, and Pb are potentially biotoxic in some stations. Correlation and principal component analyses indicate that most of the metals primarily originate from natural sources, and from maricultural activities as well. Mariculture contributes considerable Cd and Cu contamination. As and Pb comes primarily from combustion of gasoline and diesel fuel by ships.     

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.     

ENAA Studies of pollution in anoxic Black Sea sediments

The vertical distributions of five potential pollutants - Zn, As, Br, Sn, and Sb - were determined via epithermal neutron activation in the upper 50 cm of unconsolidated sediments from the Black Sea, which were collected 600 m below sea surface. This analysis demonstrated increasing concentrations towards the upper limits of sediments, which were greater than alert concentrations in the case of As and Br, and in accordance with Romanian Environment Regulations. The utilization of Chernobyl ¹³⁷Cs as a time marker allowed for dating of this region to the last 100 years.     

The distribution of heavy metals including Pb,Cd and Cr in Kendari Bay surficial sediments

The surficial coastal sediments in Kendari Bay are sampled in the field to determine the concentration and pollution level of three heavy metals (Pb, Cd and Cr). Twenty-five sampling points ranging from the inner (Wanggu River) to the outer area of the bay have been chosen. The physicochemical properties, such as temperature, pH, salinity and TDS of the overlying water, as well as the sediment type and TOC of the surficial sediments, are also measured. The total concentrations of the Pb, Cd and Cr in the sediment samples are quantified using inductively-coupled plasma mass spectrometry (ICP-MS). The concentrations of the heavy metals (Pb, Cd and Cr) ranged from 0.84 to 17.02 μg/g, 0.02 to 0.17 μg/g and 1.92 to 40.11 μg/g (dry weight), respectively, following the Cr > Pb > Cd sequence. To assess the degree of contamination, a geoaccumulation index (I_geo) is measured. Kendari Bay is not a contaminated area regarding Pb, Cd and Cr.     

Polycyclic aromatic hydrocarbons in marine sediments from the Rijeka Bay area, Northern Adriatic, Croatia, 1998-2006

The first analyses of PAHs in marine sediments within Rijeka Bay started in 1998 at three sampling sites offshore from the petroleum refinery facilities and were extended in 1999 to three more sampling points in front of the repair shipyard within the same east industrial zone. The small Svezanj cove, lying between the shipyard and the petroleum refinery was chosen as the reference point. The concentrations of PAHs were considerably higher in the shipyard environment (average: 3009-6314 μg kg⁻¹ d.w.) in comparison to the petroleum refinery area (average: 279-919 μg kg⁻¹ d.w.), while the PAHs load at reference point was close to the latter level (average: 717 μg kg⁻¹ d.w.). The Phe/Anth and Flo/Py ratios indicate the dominant pyrogenic sources, except for the results from 1999 to 2000 with dominant petrogenic origin at some sites. A declining trend of total PAHs, and consequently toxicity indices was observed at all sites.     

Bioconcentration of heavy metals in aquatic environments: the importance of bioavailability

The importance of heavy metal bioavailability on the bioconcentration in aquatic biota is examined. To this purpose, mono- and multivariate statistical techniques are applied to develop correlations between heavy metal bioconcentration factor and sediment characteristics, that are expected to affect bioavailability, using a database of heavy metal concentrations in biota and sediment along with the available physicochemical characteristics. The statistical analysis shows that satisfactory correlations are obtained only when factors that affect bioavailability, such as metal oxides concentration and organic carbon content in the sediment, are taken into account.     

Baseline survey of sediments and marine organisms in Liaohe Estuary: Heavy metals,polychlorinated biphenyls and organochlorine pesticides

A geographically extensive investigation was carried out to analyze the concentrations of heavy metals, PCBs and OCPs in the sediments and marine organisms collected from the Liaohe Estuary. In order to determine the spatial distribution and potential ecological risk of heavy metals, the surface sediments were collected from 44 sites in the Liaohe Estuary. The results showed that the heavy metal contents in the sediments were observed in the following order: Cr (11.2–84.8 mg/kg) > Cu (1.7–47.9 mg/kg) > Pb (4.3–28.3 mg/kg) > As (1.61–12.77 mg/kg) > Cd (0.06–0.47 mg/kg) > Hg (0.005–0.113 mg/kg). In comparison with the concentrations of heavy metals and POPs in other regions, the concentrations of As, Pb and DDTs in the Liaohe Estuary were generally low, and other pollutant concentrations were inconsistent with those reported in other regions. The contamination factor (CF), the pollution load index (PLI), the geoaccumulation index and the potential ecological risk index were used to analyze the pollution situation, which showed that the heavy metal pollution in Liaohe Estuary is mainly dominated by Cd and Hg. The concentrations of the four heavy metals varied significantly in the three kinds of tested organisms (fish, mollusk and crustacean), indicating the different accumulative abilities of the species. The results obtained in this study provide useful information background information for further ecology investigation and management in this region.     

湖泊沉积物中微量金属二次迁移过程中微生物作用的实验研究

蓄积在湖泊沉积物中污染物质某些情况下可以成为威胁上覆水体水质安全的二次污染源．根据贵州省阿哈湖季节性缺氧的特性,通过控制氧化还原状况,设计了对该湖沉积物-水柱的原样／抑菌条件的培养实验．实验发现,微生物活动对界面附近氧化还原反应具有控制作用;改变水体的含氧状况可以显著影响上覆水体水质,包括表观性状和水体中污染物含量．聚类分析结果表明,早期成岩过程中Mn,Ga,SO4 2-,Cu,Cr,Pb和Co,Ni,Fe,Sc,V,Rb两大类分别具有相似的地球化学行为．根据实验结果,计算了厌氧培养过程中,微量元素的最大释放量,发现铁、锰在厌氧过程中可以大量向水体释放．     

武汉典型湖泊沉积物中重金属累积特征及其环境风险

采集武汉市8个典型湖泊的表层沉积物,分析11种重金属的含量及其不同形态组成,研究了不同湖泊金属元素的富集与污染程度,探讨了沉积物中重金属的污染来源及其潜在生态风险,结果表明,沉积物中重金属Cd累积最严重,Zn和Hg也发生明显累积,龙阳湖污染较重,南太子湖和墨水湖污染中等,其它湖泊污染总体较轻.沉积物性质对重金属累积的影响不显著,城市工业活动强烈影响着重金属的分布,不同重金属的形态分布差异较大,Cd生物可利用态含量最高,其次为Mn、Zn、Co、Cu和Pb;而Sb和Hg以残留态占绝对优势,生态风险较小,相关分析和主成分分析表明,化石燃料燃烧、金属冶炼等是武汉市湖泊沉积物中重金属来源的主要贡献者,同时岩石风化等地球化学过程也影响着重金属的污染.