Heavy metal contamination in western Xiamen Bay sediments and its vicinity, China

Concentrations of selected heavy metals (Cu, Pb, Zn, Cd, Cr, Ni and Fe) in surface sediments from nine sites in western Xiamen Bay and its vicinity were studied in order to understand current metal contamination due to urbanization and economic development in Xiamen, China. The sediment samples were collected in December 2004 and July 2005 respectively in order to examine temporal variations. In this study, we found that heavy metal concentrations in surface sediments sampled in the western Xiamen Bay and adjacent Maluan Bay and Yuandang Lagoon varied from 19 to 97mg kg(-1) for Cu, 45 to 60mg kg(-1) for Pb, 65 to 223mg kg(-1) for Zn, 0.11 to 1.01mg kg(-1) for Cd, 37 to 134mg kg(-1) for Cr, 25 to 65mg kg(-1) for Ni and 3.08 to 4.81% for Fe. Although all metal concentrations in sediments meets Chinese National Standard Criteria for Marine Sediment Quality, both metal enrichment factors (EF) and geoaccumulation index (I(geo)) show that Pb contamination exists in the entire study area and contamination of other metals are also present in some locations depending on the sources, of which sewage outlets and commercial ports are the main sources of contaminants to the area. This study shows that using the sediment quality standard criteria only to assess sediments cannot properly reflect sediment contamination. A multiple approaches should be applied for the sediment quality assessment.     

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.     

Geomorphological Impact Assessment on Groundwater Quality and Fluoride Genesis along the Bay of Bengal of Visakhapatnam District,Andhra Pradesh,India

Geomorphological effects might not be the mere natural topographical changes but, their impact on groundwater quantity/quality would be an aspect of great concern. Especially the qualitative fluctuations in coastal region would suffer more than those observed in the elevated or the plains. The ease and severity would magnify from the anthropogenic activities and from the effects carried over from the uplands. To evaluate this, a study was conducted by collecting 44 water samples of bore and open well origin along the Bay of Bengal coast of Visakhapatnam district. Geochemical assessment was carried from the results of all major chemical constituents and geological data of the sampling stations. The expansive and correlative interpretation of the results yielded the mechanisms control the genesis of principle chemical species, present status, reserves, drainage pattern and the recent intrusion zones in the study area. The genesis and spatial distribution of fluoride was assessed due to sporadic reports of fluorosis in the district. Upon receiving the findings with suitable recommendations, the Groundwater Board and the civil society organizations widely published and the displayed the results for further action made the study a purposeful.     

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, enrichment and accumulation of heavy metals in coastal sediments of Alang-Sosiya ship scrapping yard, India

Since its inception in 1982, the Alang-Sosiya yard has become the largest ship scrapping works in the world. Several hundreds of ships arrive every year. The degree of heavy metal contamination has been studied in bulk and fine sediments from the intertidal zone of this ship scrapping yard, two stations, one on either side at 5 km distance and one reference station 60 km distance near Mahuva, towards the south. The samples have been subjected to a total digestion technique and analysed for elements: Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Zn and Al, and %TOC. The absolute metal concentrations reflected variations in BF and FF sediment samples with organic matter content. Enrichment factors (EF) and geoaccumulation indices (Igeo) have been calculated and the relative contamination levels are assessed at these sites. At Alang-Sosiya, the enrichment of heavy metals has been observed to be relatively high.     

Characterization of tidally influenced seasonal nutrient flux to the Bay of Bengal and its implications on the coastal ecosystem

Submarine groundwater discharge (SGD) introduces solute and nutrients to the global oceans, resulting in considerable nutrient cycling and dynamics in the coastal areas. We have conducted high‐resolution, spatio‐temporal, lunar tidal cycle patterns and variability of discharged solute/nutrient assessment to get an overview of seasonal nutrient flux to the Bay of Bengal in eastern parts of the Indian subcontinent. Whereas the premonsoon season SGD was found to be dominant in the marine influence (M‐SGD), the postmonsoon season was found to be predominated by the terrestrial component of SGD (T‐SGD), extending from coast to near offshore. The solute fluxes and redox transformation were found to be extensively influenced by tidal and diurnal cycles, overlapping on seasonal patterns. We have assessed the possible role of SGD‐associated solute/nutrient fluxes and their discharge mechanisms, and their associated temporal distributions have severe implications on the biological productivity of the Bay of Bengal. The estimated annual solute fluxes, using the average end‐member concentration of the SGD‐associated nutrients, were found to be 240 and 224 mM·m^?2·day^?1 for NO₃^? and Fe_tot, respectively. Together with huge freshwater flux from the Himalayan and Peninsular Indian rivers, the SGD has considerable influence on the bay water circulation, stratification, and solute cycling. Thus, the observation from this study implies that SGD‐associated nutrient flux to the Bay of Bengal may function as a nutrient sink, which might influence the long‐term solute/nutrient flux along the eastern coast of India.     

Assessment of heavy metal contamination in the surficial sediments from the lower Meghna River estuary,Noakhali coast,Bangladesh

Sediment samples were collected from ten selected sites of the lower Meghna River estuary,and six heavy metals were analyzed with Atomic Absorption Spectrophotometry(AAS)to assess the contamination level and the metals’association with sediment grain size.The current results revealed that the mean concentrations of the studied metals were ranked in descending order of iron(Fe)(1.29×103 mg/kg)>zinc(Zn)(42.41 mg/kg)>lead(Pb)(12.48 mg/kg)>chromium(Cr)(10.59 mg/kg)>copper(Cu)(6.22 mg/kg)>cadmium(Cd)(0.28 mg/kg).The geo-accumulation,contamination,and pollution load indexes suggested that the lower Meghna river estuary was not contaminated by Fe,Zn,Pb,Cr,and Cu.The mean size of the sediment ranged from 28.92 to 126.2 mm,and the Pearson correlation coefficient showed a significant association between Fe and Pb(coefficient of determination,r2=0.836;p<0.05),and no significant correlation was found between individual metals and grain size,indicating no or low influence on the metals distribution.     

典型小型水库表层沉积物重金属分布特征及生态风险

以典型乡镇水库通济桥水库表层沉积物为研究对象,在分析其中As、Cd、Cr、Cu、Hg、Ni、Pb和Zn等有毒、有害重金属分布特征的基础上,分析重金属来源,评价重金属污染程度及其潜在生态危害.结果表明:通济桥水库表层沉积物中,上述8种重金属均存在一定程度的污染,坝前和入库区污染物蓄积更为明显.其中,Hg和Cd的污染范围较广、污染程度较严重.受重金属Hg和Cd的影响,水库表层沉积物存在中等程度的重金属生态危害风险,其中坝前区域已处于强风险等级.为保障水库水体水质安全,防范重金属污染应提到当前水库管理工作的重要位置.     

Heavy metal contamination and ecological risk in Spartina alterniflora marsh in intertidal sediments of Bohai Bay,China

To investigate the effects of Spartina alterniflora on heavy metals pollution of intertidal sediments, sediment cores of a S. alterniflora salt marsh and a mudflat in Bohai Bay, China were analyzed. The results showed that S. alterniflora caused higher total C and P, but lower bulk density and electrical conductivity. The levels of Cd, Cu and Pb were higher in S. alterniflora sediment. Both Cd and Zn were higher than the probable effect level at both sites, indicating their toxicological importance. The geo-accumulation and potential ecological risk indexes revealed higher metal contamination in S. alterniflora sediment. Multivariate analysis implied that anthropogenic activities altered mobility and bioavailability of heavy metals. The percentage of mobile heavy metals was higher in S. alterniflora sediment, indicating improvement of conversion from the immobilized fraction to the mobilized fraction. These findings indicate that S. alterniflora may facilitate accumulation of heavy metals and increase their bioavailability and mobility.     

Evaluation of the contamination of platinum in estuarine and coastal sediments (Tagus Estuary and Prodelta, Portugal)

Platinum contamination in estuarine and coastal sediments has been evaluated in three cores collected from the Tagus Estuary and Prodelta shelf sediments. Elevated concentrations, up to 25-fold enrichment compared to background values, were found in the upper layers of the estuarine sediments. The degree of Pt enrichment in the estuarine sediments varied depending on the proximity to vehicular traffic sources, with a maximum concentration of 9.5 ng g⁻¹. A considerable decrease of Pt concentrations with depth indicated the absence of significant contamination before the introduction of catalytic converters in automobiles. Platinum distribution in the Tagus Prodelta shelf sediment core showed no surface enrichment; instead a sub-surface maximum at the base of the mixed layer suggested the possibility of post-depositional mobility, thereby blurring the traffic-borne contamination signature in coastal sediments.     

Effects of environmental regulations on heavy metal pollution decline in core sediments from Manila Bay

We investigated the high-resolution heavy metal pollution history of Manila Bay using heavy metal concentrations and Pb isotope ratios together with ²¹⁰Pb dating to find out the effects of environmental regulations after the 1990s. Our results suggested that the rate of decline in heavy metal pollution increased dramatically from the end of the 1990s due to stricter environmental regulations, Administrative Order No. 42, being enforced by the Philippines government. The presented data and methodology should form the basis for future monitoring, leading to pollution control, and to the generation of preventive measures at the pollution source for the maintenance of environmental quality in the coastal metropolitan city of Manila. Although this is the first report of a reduction in pollution in Asian developing country, our results suggest that we can expect to find similar signs of pollution decline in other parts of the world as well.     

孟加拉湾夏季风爆发的判断指标及其年际特征

利用高低层大气环流、OLR（向外长波辐射）、CMAP降水、SST（海表温度）等资料分析了孟加拉湾地区3—5月多年气候平均大气环流及不同要素的演变特征,定义了一个新的孟加拉湾夏季风（BOBSM,下同）爆发指标为孟加拉湾地区（5°N—15°N,90°E—97.5°E）850 hPa和200 hPa纬向风区域平均的变化同时满足U850 > 3 m·s^-1和U200 < -5 m·s^-1,并持续5天的第一天即作为BOBSM爆发日期.该季风指数有明确的天气学意义,可以反映孟加拉湾低层西南风持续稳定和南亚高压在青藏高原建立早晚的特征.文章进一步分析了BOBSM爆发的年际特征及其前兆海洋信号特征,结果表明：1981—2010年BOBSM爆发的平均日期为5月10日,季风爆发有显著的年际波动,爆发最早在1999年（4月11日）和最晚在1968年（6月1日）,年代际尺度上表现为由爆发偏晚至偏早的变化趋势;BOBSM爆发早（晚）与热带印度洋地区850 hPa的越赤道气流和西风异常加强（减弱）,以及200 hPa青藏高原南亚高压的季节性建立偏早（晚）等密切联系;前期冬季赤道西太平洋的海温冷（暖）变化对BOBSM爆发早（晚）有很好的指示意义,前期冬季海温偏高（低）有利于季风偏早（晚）,其影响的主要途径是通过热源变化激发纬向垂直环流及其热带印度洋和太平洋低层环流异常,进而影响季风爆发早晚.

     

Present state and historical changes of trace metal pollution in Kaoping coastal sediments, southwestern Taiwan

Surface and gravity-cored sediments were collected from the Kaoping coastal area off southwestern Taiwan to determine particle size, organic carbon, trace metal concentration and enrichment factor (EF), 210Pb dating, and 206Pb/207Pb ratio for determining present and historical metal pollution. Surface distributions of trace metals ranged from 0.02 to 0.13 mg/kg for Cd (EF: 0.16-1.65), from 35 to 189 mg/kg for Cr (EF: 0.85-2.92), from 25 to 64 mg/kg for Ni (EF: 0.53-2.38), from 10 to 32 mg/kg for Pb (EF: 1.20-4.94), and from 29 to 129 mg/kg for Zn (EF: 1.18-3.50). Trace metal concentrations correlate closely with distributions of mud (<63 microm) and organic carbon which accumulate largely around river mouths and within the Kaoping Canyon. With the exception of Cd, Cr and Ni in certain areas with rather coarse sediments, metals were generally elevated above the baseline levels over the studied area. Metals were also relatively enriched in areas with high contents of mud and organic carbon. Sedimentation rates derived from the excess 210Pb data in core sediments sampled from the canyon illustrate metal pollution beginning around 1970 that is corresponding to the booming time of economic growth in Taiwan. Meanwhile, the status of Pb pollution in core sediments is verified by an inversed correlation between 206Pb/207Pb ratios and Pb concentrations. Anthropogenic Pb and other metals in the studied area were apparently derived primarily from the Kaoping River and accumulated around the river mouth and within the Kaoping Canyon. The Kaoping Canyon appears to act as a major sink for river borne trace metals.     

太湖梅梁湾沉积岩芯元素地球化学记录的多元统计分析

通过沉积岩芯元素含量垂直分布和富集因子分析,结合多元统计方法如系统聚类和模糊聚类分析,研究了太湖梅梁湾沉积岩芯元素地球化学记录的湖泊环境演化过程.以系统聚类分析和模糊聚类分析为基础,将梅梁湾地球化学记录的环境过程划分为如下几个层段:0-6cm为人类活动强烈干扰的阶段,25-50cm和55-72cm层段都是自然过程的表现,反映了流域物源的影响,而两层段元素记录的差异反映了不同自然作用驱动下的湖泊环境变化;6-25cm和50-55cm层段则是不同环境特征的过渡阶段,因此,综合应用多元统计方法可以更直观更精确地量化影响湖泊环境的因素,有助于恢复湖泊环境历史演化过程.     

Assessment of the historical trace metal contamination of sediments in the Elizabeth River, Virginia

Two sediment cores (Southern Branch, PC-1, and Western Branch, WB-2) were taken from the highly industrialized Elizabeth River, Virginia. The concentrations of trace metals cadmium, cobalt, chromium, copper, nickel, lead and zinc, major elements iron, manganese and aluminum, organic carbon content and the specific surface area of the sediments were determined in each of the cores. Down-core variations in metals varied significantly in each core with maximum contamination events occurring at different times in different portions of the river. In PC-1, maximum metal concentrations were seen after the appearance of (137)Cs. In contrast, the highest levels in WB-2 occurred well before the appearance of (137)Cs. Although stricter environmental regulations have caused a decrease in metal concentrations since the 1980s, the concentrations in the surface sediments of many trace metals were elevated to levels 2-5 times higher than the levels at the bottom of the cores in both the Southern and Western Branches of the river.     

Evaluations of heavy metal pollution in sediment and Mullus barbatus from the Izmir Bay (Eastern Aegean) during 1997-2009

Izmir Bay is one of the great natural bays of the Mediterranean. The surface sediment and fish samples were collected during 1997-2009. The sediment concentrations of inner bay showed significant enrichments during sampling periods. Outer and middle bays exhibited low levels of metal enrichments except the estuary of Gediz River. The concentrations were generally higher than the background levels from the Mediterranean and Aegean except Cd and Pb levels gradually decreased. Metal EF is used as an index to evaluate anthropogenic influences of metals in sediments. Maximum metal enrichment was found for Hg in the outer bay, while Pb indicated maximum enrichment in the middle-inner bays. Metal levels were evaluated in sediments in accordance with the numerical SQG of the USEPA. The levels of fish tissues were lower than the results reported from polluted areas of the Mediterranean. The highest BAFs were detected for Hg and Cd in fish.     

Sediment concentrations of heavy metals in the Homa Lagoon (Eastern Aegean Sea): Assessment of contamination and ecological risks

The concentrations of heavy metals and organic carbon in sediment of the Homa Lagoon which is one of the most productive lagoons and commercial important active fish trap in the Eastern Aegean Sea, were investigated in order to describe the temporal and spatial distributions of metals. These results were used to evaluate possible ecological risks that could be a problem for the environment of the lagoon in the future. Sediments were enriched with Cr, Ni and considered as heavily polluted per the SQG. The C_f of Ni and Cr were presented moderate level of contamination in this area. The C_d levels indicated moderate degree of contamination at station B, C, D and E due to agricultural drainage water, industrial and domestic wastewater, are transported by the Gediz River. Sediments from Homa Lagoon were most toxic for Ni due to exceedances of the TEL and PEL values.     

Metal enrichment in beach sediments from Chennai Metropolis, SE coast of India

A survey on the Partially Extracted Trace Metals (PETMs) concentration (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) in beach sediments is reported for the first time from 57 different locations in Chennai Metropolitan City of Southeast coast of India. The concentration of PETMs suggests that they are mainly concentrated with organic matter in the crowded part of the industrial regions in the beaches from the northern part rather than the tourist beaches in the southern part of the city. The comparison on enrichment of trace metals indicates higher values of Pb, Ni in the beaches than lowest effect level (LEL) and effects range low (ERL) than the tourist beaches.     

Textural and geochemical characteristics of off shore sediment of North Bay of Bengal:A statistical approach for marine metal pollution

Metal pollution study on sediments of North Bay of Bengal sediments presented in this paper is based on existing Lithostratigraphy of upstream,mineralogy and geochemical analysis of 42 sediment samples.The statistical analysis identifies the metal pollution as well as its apparent source in the off shore regions.Samples were analyzed for grain size,organic content and heavy metals(Fe,Mn,Cr,Cu,Ni,Pb,Cd,Zn and Co) using the sequential extraction method to evaluate geochemical processes and pollution load.In an effort to surmise anthropogenic input,several approaches including classification by quantitative indexes such as enrichment factor,contamination factor,degree of pollution,pollution load index and geo accumulation index,were attempted.Metal speciation results indicate high%of Cd in exchangeable fraction of Mahanadi transect sediments where as a considerable amount of oxidizable fraction of Cr was detected at Dhamra.Quantitative indexes place North Bay of Bengal under moderately polluted zone due to high level of Cd.Normalization of metals to Fe indicated relatively high enrichment factors for Cd and Cr.Factor analysis identified seven possible types of geochemical associations where sediment pH plays a major role for the heavy metal mobility.The higher Cd concentration in exchangeable fraction as well as the higher EF for Cd and Cr present in sediment may pose a risk of secondary water pollution under slightest disturbance in the geo-chemistry of sediments.Comparison study with available data of near costal zones and upstream stratigraphy revealed that open cast mining,overburden dumping,mineral based industrial effluents were the major source of pollution for catchment area contamination.Bay of Bengal is likely to face a serious threat of metal pollution with the present deposition rates unless rigorous pollution control norms are applied.     

Evaluation of sediment contamination in the Red Sea coastal area combining multiple pollution indices and multivariate statistical techniques

In the recent years,the Red Sea coast of Yemen has been severely affected by intensive anthropogenic activities.The current study constitutes a thorough inquiry to evaluate the extent of heavy metals pollution in Yemen's Red Sea coast sediment and identifies the possible sources of pollution.The concentrations of five metals(copper(Cu),zinc(Zn),cadmium(Cd),lead(Pb),and nickel(Ni))collected from nine sites along the Red Sea coast of Yemen were assessed using an atomic absorption spectrophotometer(ASS).Sediment quality indices,such as the sediment quality guidelines(SQGs),potential ecological risk(RI),contamination factor(CF),pollution load index(PLI),geoaccumulation index(Igeo),and modified degree of contamination(mCd)were computed.In addition,multivariate statistical techniques(principal component analysis(PCA),hierarchical cluster analysis,and Pearson's correlation analysis)were applied to identify the potential sources of metals.The mean concentrations of Cu,Zn,Cd,Pb,and Ni were 51.3,61.9,4.02,9.9,and 33.4 mg/kg dry wt,respectively.The spatial distribution revealed that the metals concentrations were high at the middle zone and low southward of Hodeida city.According to the SQGs,the adverse biological effects of metals were occasionally associated with Cu and Cd,frequently associated with Ni,and not expected to occur with Zn and Pb.The RI indicated that the sediment of the studied sites pose low(RI<50)to considerable(100≤RI<200)ecological risk.The mean effect range-median quotient(M-ERM-Q)indicated that the combination of the studied metals had the toxicity probability of 21%at all studied sites.Igeo and CF indicated that the metals concentrations were in the descending order of:Zn>Ni>Pb>Cd>Cu,whereas the PLI and mCd indicated that Ras Isa(Site 5)and Urj village(Site 6)were the most polluted sites.PCA,cluster analysis,and correlation analysis found that Cd,Pb,and Ni mostly originated from anthropogenic sources while Cu and Zn were mainly derived from natural sources.Thus,it is evident that the intensive anthropogenic activities had negative influence on metals accumulation in the sediment of the Red Sea coast of Yemen leading to detrimental effects to the whole ecosystem.These comprehensive findings provide valuable information and data for future monitoring studies regarding heavy metals pollution and sediment quality at the Red Sea coast of Yemen.