Distribution and fractionation of heavy metals in the surface sediments of the Ganges- Brahmaputra-Meghna river system in the Bengal basin

 The lower Ganges-Brahmaputra-Meghna (G-B-M) drainage basin occupies the total Bengal Basin, which is one of the unique basins of the world because of its location and size, density of population, and catastrophic deposition of sediments. The increased heavy metal concentration in the 63 m fraction of surface sediments shows similarity among major segments of the G-B-M system in the basin, which reflects the homogenization of lithologic and chemical diversity of the greater denudation regime by the river processes. The differences in heavy metal concentation in the lower G-B-M system with that of its upper and middle counterpart is mainly related to the contrast between Himalayan rivers and the other major South Asian rivers, and may be due to the geological differences of their denudation regime. Heavy metals in the Lower G-B-M system have an affinity towards the clay fraction of the sediments. The correlation matix of heavy metals in the lower Brahmaputra and Meghna suggests the importance of Fe-Mn oxyhydroxides in their accumulations. Iron, Ti and Mn are higher in the Meghna main channel, Zn is higher in the Meghna tributaries, and Cr is higher in both the Brahmaputra and Meghna compared to the value for standard shale. The enrichment factor is ≤1 for most of the metals except Mn which is relatively higher in the Meghna and lower Ganges main channels. The geoaccumulation index (I_geo) for most of the heavy metals lies below grade zero, suggesting unpolluted sediment quality. The lower Ganges system shows relatively higher concentration in the nondetrital fraction of heavy metals, probably due to the presence of petroleum refinery, industrial and mining effluents, and agricultural runoff in the drainage basin. The relative uniformity in concentration of heavy metals in vertical profiles may be due to the uniformity in sediment grain size and catastrophic deposition of sediments, where the time period represented by the vertical sediment column is not enough to reflect the cultural accumulation of heavy metals. The Bengal basin thus represents a relatively unperturbed alluvial basin with regards to heavy metal pollution. Received: 21 July 1997 · Accepted: 13 October 1997     

金矿区河水和底泥中重金属含量分布与耦合关系

河流中河水与底泥中重金属含量之间的关系对于河流污染防治意义重大。对某金矿区3种典型河流的河水与底泥中的重金属含量进行分析,发现4条河流均有超过国家标准限值的情况,河水中7种重金属元素均出现超标,Cr、As元素超标不严重;底泥中Hg、Pb、Cr、Cu、Zn超标,其中Hg超标最严重,河水和底泥中Hg最大超标倍数分别达到3099倍和244倍。河流中重金属主要赋存形态为沉积态,底泥的吸附解吸作用是河流底泥和河水中重金属沿程变化的主控因素;金矿区区域上河水和底泥中重金属很好地服从Langmuir等温吸附模式。矿业活动、地层岩性均会影响底泥对重金属的平均最大吸附容量,流径黄土区的双桥河平均最大吸附容量最大。研究结果为矿山河流污染防治与预警提供了参考依据。     

Heavy-metal pollution of sediments from the Polish exclusive economic zone,southern Baltic Sea

Analysis of 59 surface sediment samples from the Polish exclusive economic zone (EEZ) shows that Szczecin Lagoon sediments are the most polluted by heavy metals and that the degree of heavy-metal pollution decreases substantially on passing from the Szczecin Lagoon to the Pomeranian Bay and the inner shelf area and then on passing to the Bornholm Deep and Słupsk Furrow. Heavy-metal pollution in the sediments of the western part of the Polish EEZ therefore appears to follow the dispersion of the Oder River. Fluffy material from the Oder estuary appears to be the main source of heavy metals in the muddy sediments of the Bornholm Deep. The formation of sulphides is therefore not the principal factor controlling the enrichment of heavy metals in the sediments of this anoxic basin, although it may be responsible for the uptake of Mo, Sb and As. Two main factors control the distribution of the rare earth elements (REE) in sediments of the Polish EEZ: the input of Fe-organic colloids from rivers and the presence of detrital material in the sediments.     

雄安新区白洋淀表层沉积物重金属地球化学特征及生态风险评价

【研究目的】白洋淀为雄安新区核心生态功能区,为支撑白洋淀湿地生态修复与保护,系统开展了全淀区表层沉积物环境质量调查。【研究方法】在白洋淀湿地采集表层沉积物样品484组,查明了白洋淀表层沉积物重金属地球化学特征,并采用地累积指数法、潜在生态风险指数法等多种方法开展了重金属生态风险评价。【研究结果】白洋淀表层沉积物重金属含量普遍偏高于河北省表层土壤重金属含量背景值,府河入淀口及白沟引河入淀口为重金属元素主要富集区,入淀河流输入为白洋淀重金属主要来源;环境地球化学综合评价结果为清洁无污染等级分布面积144.54 km²,占表层沉积物分布总面积的96.68%;各重金属污染程度由重到轻排序为Cd＞Cu＞Hg＞Pb＞Zn＞Ni＞Cr＞As,Cd元素污染程度等级以中度和偏中度为主,Cu元素以轻度和清洁为主,其他元素以清洁无污染为主;重金属潜在生态风险以轻度和中度为主,河流入淀口所在淀区重金属潜在生态风险高于其他淀区,潜在生态风险由高到低排序为南刘庄＞烧车淀＞小白洋淀＞王家寨＞藻苲淀＞捞王淀＞池鱼淀＞泛鱼淀。【结论】白洋淀表层沉积物环境质量总体较好,南刘庄等局部淀区存在重金属污染潜在生态风险,以Cd元素污染最为突出。创新点：采用地累积指数法、潜在生态风险指数法等多种方法,系统评价白洋淀湿地表层沉积物重金属污染程度和生态风险;重金属地球化学特征分析与主成分分析法相结合,揭示表层沉积物重金属污染主要来源为河流输入。     

Heavy metal distribution in the Godavari River basin

Suspended and bed sediments collected from the entire region of the Godavari River basin were analyzed for Fe, Mn, Cr, Cu, Ni, and Zn. There are pronounced temporal and spatial variations in the heavy metal distributions. The concentrations of heavy metals in the suspended sediments are significantly higher than the bed sediments.Throughout the basin heavy metals are enriched in the finer fractions (<2 µm) of the bed sediments. The average heavymetal composition of the sediments is higher when compared to the average Indian river sediments. Heavy-metal concentration in the two shallow cores collected shows, to some extent, the influence of urbanization. When compared to the other tropical Indian rivers such as the Krishna, the Godavari appears to be a significant contributor of heavy metals to the Bay of Bengal. Considering the enormous sediment load of the Godavari River—170 million tons/yr, the heavy metal fluxes to the Bay of Bengal is very significant. Except for the Pranhita, other tributaries of the Godavari do not contribute significant loads of heavy metals. All the metals show high correlation among themselves and the correlation is more pronounced in suspended sediments than in the bed sediments. The heavy-metal distribution, fractionation, and its relationship with total suspended sediments and depth in various parts of the basin are discussed in detail.     

松花江上游表层沉积物中重金属元素时空分布特征

松花江是我国七大河流之一,研究其底泥重金属元素的时空分布特征对流域的水环境治理具有重要意义。本文对松花江（哈达山至松花湖段）底泥（表层沉积物）中元素As、Hg、Cr、Cd、Pb的分布特征进行了研究,并利用地累积指数分析了这些元素的污染状况。结果表明：研究区底泥几乎未受到As、Cr和Pb的污染,但多数地段内出现了Cd和Hg的污染,尤其是元素Hg,在个别地段的污染程度达到了极强;与10年前相比,一些重金属的污染得到了明显改善,但吉林市区段内Hg的污染仍非常严重。污染样品空间分布特征表明,松花江吉林市区段可能有来自工农业废水的重金属污染。     

吉林省部分河流与湖泊表层沉积物中重金属的分布规律

河流的水化学组成具有多样性和易变性,而湖泊水则因其交换缓慢,即使与河流所在地区的气候条件和地球化学条件相似,其化学组成也明显区别于河流,沉积物中重金属的分布也不同.利用形态分析、相关分析和地累积指数法研究了吉林省境内部分河流、湖泊沉积物重金属分布规律.研究结果表明,伊通河和南湖重金属元素生物可利用态含量都很高,存在较大的、潜在的生态危害,Pb、Cu在有机物态中表现出明显的赋存趋势;河流沉积物中Cu、Pb、Zn与pH值显著相关,但湖泊中却相关性不显著.河流沉积物受重金属污染较严重,污染程度最高达到4级,属强污染,湖泊污染程度较轻.     

Heavy metals in Oka river sediments (Urdaibai National Biosphere Reserve, northern Spain): lithogenic and anthropogenic effects

 The Oka River basin is located in the Urdaibai National Biosphere Reserve, North Spain. In order to obtain a preliminary view of its environmental conditions, nitric acid extractable Fe, Mn, Zn, Pb, Cu, Cr, Ni and Co, organic matter content (L.O.I.), geochemical fractionation of heavy metals and mineralogical composition were analysed in surficial sediments (fraction <63 μm) collected in October 1991. Relatively high concentrations of metals occurred in a sampling site upstream, due to a local natural enrichment controlled by weathering of volcanic rocks. Geochemical fractionation confirmed the lithogenic origin of metals, which were mainly associated to the detrital phase. The significant increase of heavy metals found in some samples collected in the municipal area of Gernika suggested a pollution effect, related to anthropogenic wastes. Large amounts of metallic slags have been found mixed with the sediments upstream from this locality. Nevertheless, in view of their composition, it is unlikely that these slags constitute a significant source of heavy metals in the studied area. In a second sampling in October 1997 an apparent decreasing trend in some heavy metal levels was noted, particularly for Pb and Cu. Nowadays, enrichment factors relative to background values confirm moderate anthropogenic influence on Zn, Pb, Cu, Cr and Ni concentrations. However, heavy metal levels in the Oka river sediments are much lower than those detected in other major rivers of the Basque Country (Nervión, Urumea, Deba). Received: 7 July 1997 · Accepted: 4 July 1998     

Land disposal of river and lagoon dredged sediments

The Jacarepaguá lagoon system, in the Western part of the city of Rio de Janeiro, Brazil, with an area of 8 km² receives the contributions of a number of rivers crossing largely populated and industrial areas without adequate sanitation and drainage. Since 1996 studies have been carried out to assist future dredging works and disposal of rivers and lagoons sediments. These studies included full characterization of these sediments and evaluation of the contamination of the dredged material with emphasis on the assessment of heavy metals. The present paper report these studies to assess a large dredging programme of about 3.8 million m³ of the river basins and 4 million m³ of lagoons sediments to be disposed inland.     

Heavy metal accumulation in river sediments: A response to environmental pollutionSchwermetall-anreicherung in fluviatilen sedimenten als ausdruck der verschmutzung unserer umwelt

As evidenced by catastrophic cadmium and mercury poisonings in japan, heavy metals belong to the most toxic environmental pollutants. Through the investigation of sediments, the extent, distribution and provenance of heavy metal contamination in rivers and lakes can be determined and traced. Eight heavy metals from the clay fraction of sediments from major rivers within the Federal Republic of Germany were determined by means of atomic adsorption spectrometry. Heavy metals especially known for their high toxicity are enriched most: mercury, lead and zinc by a factor of 10; cadmium by a factor of 50, as compared with the natural background of these elements. A mobilisation of heavy metals from the suspended load and from the sediments, as to be observed in rivers approaching the marine enviromment, could endanger marine organisms, thus negatively influencing the acquatic food chain. With a further increase of heavy metal pollution, a threat to the drinking water supplied by rivers and lakes cannot be excluded.     

太湖MS岩芯重金属元素地球化学形态研究

采用BCR三步提取法对太湖MS岩芯沉积物中Cu、Fe、Mn、Ni、Pb和Zn等6种重金属元素的化学形态进行了研究.结果表明,有效结合态的Cu、Ni和Pb主要以有机物及硫化物结合态、Fe-Mn氧化物结合态存在,Fe和Zn主要以Fe-Mn氧化物结合态存在,Mn主要以可交换态及碳酸盐结合态存在;Fe-Mn氧化物结合态的Ni、Pb和Zn与可还原态的Mn有较好的正相关关系,有机物及硫化物结合态的Cu、Mn、Ni、Pb和Zn与有机碳含量有较好的正相关关系;重金属形态分布体现了重金属元素地球化学性质的差异,以及重金属形态含量与沉积物理化性质的关系.沉积岩芯重金属元素形态垂向变化规律及次生相富集系数表明,Cu、Mn、Ni、Pb和Zn在沉积岩芯13～4 cm有效结合态含量较稳定,为自然沉积;4～0 cm有效结合态含量明显升高,存在一定程度的人为污染.根据137Cs测年结果判断,沉积岩芯Cu、Mn、Ni、Pb和Zn等重金属污染开始于20世纪70年代末期,主要污染元素及污染历史与太湖流域污染工业类型及经济发展阶段相吻合.     

Environmental magnetic and geochemical characteristics of Chennai coastal sediments,Bay of Bengal,India

In this study, environmental magnetic, heavy metal and statistical analyses were conducted on 21 surface sediments collected from Chennai coast, India, to examine the feasibility of heavy metal pollution using magnetic susceptibility. The Chennai coastal sediment samples are dominated by ferrimagnetic minerals corresponding to magnetite-like minerals. The percentage of frequency dependent magnetic susceptibility reflects the presence of super-paramagnetic/single domain magnetic minerals in Chennai harbour, Cooum and Adayar rivers sediments. High pollution load index in sample E1, E2, CH7, C11, C12 and A16 is mainly due to anthropogenic activities such as, harbour activities, Cooum and Adayar rivers input and industrial effluent. Factor analysis shows that the magnetic concentration dependent parameters (χ, χ _ARM and SIRM) covary with the heavy metal concentrations, suggesting that the input of magnetic minerals and heavy metals in Chennai coastal sediments are derived from the same anthropogenic sources. Strong correlation obtained between pollution load index (PLI) and concentration dependent parameters (χ, χ _ARM and SIRM) for the polluted samples with magnetic susceptibility excess of 50×10^− 8 m³kg^− 1. Significant correlations between heavy metals and magnetic susceptibility point out the potential of magnetic screening/monitoring for simple and rapid proxy indicator of heavy metal pollution in marine sediments.     

Heavy metals distribution in the sediments of ganges and Brahmaputra rivers

Bed sediments were collected from the entire region of the Ganges basin and some parts of the Brahmaputra. In addition, selected stations were sampled for suspended sediments as well. The samples were analysed for a number of heavy metals (Fe, Mn, Ni, Cr, Cu, and Zn) by the thin-film energy dispersive X-ray fluorescence technique. There are pronounced temporal and spatial variations in the heavy metals distributions. Suspended sediments are 5–10 times richer than the bed sediments. None of the tributaries contribute significant heavy metal load, but around urban areas in Yamuna (tributary of Ganges), very high levels due to the distribution from the drainage network are observed. Compared to the Brahmaputra, the distribution and fractionation of heavy metals in the Ganges sediments are more erratic and highly variable. All the metals considered show high correlation among themselves. Given the high flux of suspended sediments from the Himalayan rivers (nearly 20% of the global flux), the worldwide budget for heavy metal transport may need to be suitably revised.     

Distribution of heavy metals and pollution pathways in a shallow marine shelf: assessment for a future management

The spatial distribution and geoaccumulation indices of four heavy metals were investigated in very shallow marine sediments of southwestern Spain. Surface sediments were collected from 43 sites with water depth ranging from 3 to 20 m. High to very high pollution levels (I _geo > 4 for zinc, lead and copper) were detected near the end of the Huelva bank, whereas chromium shows a more hazardous distribution in the southwestern Spanish littoral. Low to moderate heavy metal contents (mainly zinc and lead) were also observed in other two areas at different water depths (Isla Cristina-Piedras River: 10–18 m water depth; Mazagón–Matalascañas: <10 m water depth), whereas unpolluted to moderately polluted sediments were detected in the very shallow zones (<8 m water depth) located between the mouths of the Guadiana and the Piedras Rivers. A regional scenario indicates a strong pollution of the adjacent marine areas by polluted inputs derived from the Tinto–Odiel rivers, with a partial transport of heavy metals by W–E littoral currents even 40 km eastward. The Guadiana River is an additional source of zinc–lead contamination near the Spanish–Portuguese border, mainly at water depths up to 10 m. All these rivers are affected by acid mine drainage processes, derived from millennial mining activities. This pollution affects the sediment quality even 40 km eastward.     

Magnetic,geochemical and mineralogical properties of sediments from karstic and flysch rivers of Croatia and Slovenia

The aim of the present work was to investigate links between the low-field magnetic susceptibility (MS) and chemical and mineral composition of sediments from several Croatian and Slovenian rivers, as well as to determine possible anthropogenic influence on these sediments. MS measurements are a fast and simple method, which serves as a proxy for the estimation of pollution in different environmental systems. The investigated rivers are predominantly unpolluted rivers from Croatian and Slovenian karstic and flysch areas, which belong to the Adriatic or the Black Sea watersheds: the Dragonja, the Mirna, the Ra?a, the Ri?ana, the Reka, the Rak, the Cerkni?nica, the Unec and the Ljubljanica rivers. It was assumed that, due to their mostly unpolluted status, they could serve as a database for natural MS background values for this region. For comparison, several rivers and a lake from the Celje old metallurgic industrial area (Slovenia) were also investigated: the Savinja, the Hudinja, the Voglajna rivers and Slivni?ko Lake. They form a sub-basin of the Sava River drainage basin. Sediments of the clean karstic and flysch rivers showed extremely low MS values, with mass susceptibility values ranging from 0.58 × 10^?7 to 5.11 × 10^?7 m³/kg, and isothermal remanent magnetism (IRM) values ranging from 0.71 to 7.88 A/m. In the Celje industrial area, river sediments showed much higher MS values, with mass susceptibility values ranging from 1.31 × 10^?7 to 38.3 × 10^?7 m³/kg, and IRM values ranging from 0.91 to 100.42 A/m. The highest MS value was found in the Voglajna River at Teharje-?tore, a point which showed a significant number of anomalies of toxic metals in earlier investigations. Semiquantitative determination of relations between grain size and concentration of magnetite was performed using the Thompson-Oldfield method. X-ray diffraction (XRD) mineralogical analysis showed that sediments of the Celje area have mostly quartz as major mineral, with relatively small amount of carbonate minerals, while in sediments of karstic rivers carbonate minerals prevail. Statistically significant correlations were obtained between MS and Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Ba in the Slovenian karstic region and between MS and Cr, Fe, Co, Ni and Zn in flysch drainage basins. On the contrary, no correlation of MS and Hg content was obtained.     

Influence of the Yangtze River and grain size on the spatial variations of heavy metals and organic carbon in the East China Sea continental shelf sediments

Bulk heavy metal (Fe, Mn, Zn, Cu, Pb, Cd), Al, organic carbon and carbonate concentrations, grain sizes, and δC¹³ of the organic carbon distributions were studied in sediments collected throughout the East China Sea continental shelf and the Yangtze River Delta. The results demonstrated that terrigenous sediments from the Yangtze River is a dominating factor controlling the spatial variations of heavy metals and organic carbon concentrations on the East China Sea continental shelf. In addition, grain size and recent anthropogenic influences are also major factors modifying the spatial and vertical variations of heavy metals.Large spatial variations with a band type distribution of heavy metals, grain size, organic carbon and carbonate were observed. Higher concentrations of heavy metal and light δC¹³ of the organic carbon were found primarily in the Deltaic and inner shelf sediments. The band type distribution generally followed the coastline with little variations in the north–south direction. Away from the Delta and inner shelf (west–east direction), most heavy metal concentrations decreased rapidly with the exception of Cd where high concentrations of Cd were also found in the carbonate-rich shelf break sediments. Coarse-grained relict sediments and biogenic carbonate are two primary diluting agents for the fine-grained aluminosilicate sediments from the Yangtze River with high concentrations of heavy metals.Unusually high concentrations of Cu, Pb, and Cd showed both spatially and vertically that more pollution prevention measures are needed in the Yangtze River drainage basin in order to prevent further heavy metal pollution of the East China Sea inner continental shelf.     

太湖沉积物中重金属的测定及环境意义

通过对太湖地区水域湖泊沉积物中重金属含量的抽样测试，描述了太湖水域重金属（Ag、As、Cd、Cr、Cu、Hg、Ni、Pb、Zn等）元素的污染状及其分布，结果表明：太湖沉积物中重金属含量北部明显高于东部，来自太湖北岸城镇和工业区的未处理工业及生活污水，对太湖北部水域造成的重金属污染程度远高于以养殖业为主的东太湖及湖心水域。     

Heavy metal distribution in surface sediments of the Tirumalairajan river estuary and the surrounding coastal area, east coast of India

Surface sediments collected at the Tirumalairajan river estuary and their surrounding coastal areas were analyzed for the bulk metal concentration. The sediments were collected from post- and premonsoon seasons. Dominances of heavy metals are in the following order: Fe > Mn > Zn > Pb > Cu in both seasons from estuary and coastal area. The results reveal that Fe, Mn, Cu, Pb, and Zn demonstrated an increased pattern from the estuary when compared to the coastal area. The heavy metal pattern of the sediments of the Tirumalairajan river estuary and its surrounding coastal area offered strong evidence that the coastal area was a major source of heavy metals to the estuarine region. For various metals, the contamination factor and geoaccumulation index (I _geo) have been calculated to assess the degree of pollution in sediments. The contamination factor and geoaccumulation index show that Zn, Pb, and Cu unpolluted to moderately pollute the sediments in estuarine part. This study shows the major sources of metal contamination in catchment and anthropogenic ones, such as agriculture runoff, discharge of industrial wastewater, and municipal sewage through the estuary and adjoining coastal area.     

Geochronology of priority pollutants in sedimentation zones of the Volga and Danube delta in comparison with the Rhine delta

Six sediment cores were taken in sedimentation zones of the Volga river (located in the southern part of the Russian Federation) and, additionally, 6 sediment cores were taken in several lakes (sedimentation zones) in the central and western part of the Danube delta in Romania. Priority pollutants (8 metals, 7 polychlorinated biphenyls and 10 polycyclic aromatic hydrocarbons) were determined in all samples of all cores. Present-day and historical levels of pollutants since the late 1930s were established through the use of radionuclide time tracers (¹³⁷Cs, ¹³⁴Cs). For the persistent metals and polycyclic aromatic hydrocarbons, trends in the concentration profiles during the last 5 decades are described. Low and hardly changing concentrations of As, Cu, Zn and all studied PAHs were observed during the last five decades in the sediments of the Volga river. Recently deposited sediments show slightly increasing levels for the heavy metals Zn and Cr and As in the Volga delta. For the studied metals and PAHs, maximum concentrations were found around 1987 in the sediments of the Danube delta. Sediments deposited around 1940 and recently deposited sediments in the Danube delta showed lower pollutant levels. If the contents of heavy metals, PAHs and PCBs in the aquatic sediments in the deltas of the rivers Rhine, Danube and Volga are compared, it is clear that the Volga delta is and was the cleanest delta during the last 5 decades. Nowadays the contents of heavy metals (except Cu and Ni), PAHs and PCBs in the aquatic sediments of the river Rhine are still highest compared to the other two rivers. The recent load of heavy metals (except Cd and Zn) in the sediments of the river Danube is the highest compared to the other two rivers.     

Geochemical records of sediments in the Eastern Gotland Basin—products of sediment dynamics in a not-so-stagnant anoxic basin?

Geochemical data from 4 cores taken in the Eastern Gotland Basin of the Central Baltic Sea (68 to 243 m water depth) show that depositional conditions for heavy metals in sediments were similar at all water depths prior to anthropogenic influxes. After the onset of industrialization, the deep anoxic parts of the basin expanded at irregular intervals and the <63 μm fractions of the sediments became characterized by high organic C and heavy-metal accumulation rates. The difference between the enrichment patterns in the basin and on the slope suggests that material enriched in organic matter (and associated trace elements) and in sulphides (and associated trace elements) is preferentially deposited in the basin. The composition of the sediments in the basin therefore reflects the effects of lateral transport of the sediment, which enriches organic C in the deepest part of the basin and of anoxia in the deep water of the basin, where metal sulphides are formed. Previous estimates of the timing of the onset of industrial pollution in the Central Baltic may have been in error because these new data suggest that this began in the Eastern Gotland Basin in about 1870.