Environmental geochemistry of El Temsah Lake sediments, Suez Canal district, Egypt

The heavy metal contents of Mn, Ni, Cu, Zn, Cr, Co, Pb, Cd, Fe, and V in the surface sediments from five selected sites of El Temsah Lake was determined by graphite furnace atomic absorption spectrophotometer. Geochemical forms of elements were investigated using four-step sequential chemical extraction procedure in order to identify and evaluate the mobility and the availability of trace metals on lake sediments, in comparison with the total element content. The operationally defined host fractions were: (1) exchangeable/bound to carbonate, (2) bound to Fe/Mn oxide, (3) bound to organic matter/sulfides, and (4) acid-soluble residue. The speciation data reveals that metals Zn, Cd, Pb, Ni, Mn, Cu, Cr, Fe, and V are sink primarily in organic and Fe–Mn oxyhydroxides phases. Co is mainly concentrated in the active phase. This is alarming because the element is enriched in Al Sayadin Lagoon which is still the main site of open fishing in Ismailia. Average concentration of the elements is mostly above the geochemical background and pristine values of the present study. There is a difference on the elemental composition of the sediment collected at the western lagoon (Al Sayadin Lagoon), junction, the shoreline shipyard workshops, and eastern beach of the lake. Depending upon the nature of elements and local pollution source, high concentration of Zn, Pb, and Cu are emitted by industrial wastewater flow (shoreline workshops), while sanitary and agricultural wastewater (El Bahtini and El Mahsama Drains) emit Co and Cd in Al Sayadin Lagoon. On the other hand, there is a marked decrease in potentially toxic heavy metal concentrations in the sediments at the most eastern side of the lake, probably due to the successive sediment dredging and improvements in water purification systems for navigation objective. These result show that El Temsah receives concentrations in anthropogenic metals that risk provoking more or less important disruptions, which are harmful and irreversible on the fauna and flora of this lake and on the whole ecobiological equilibrium.     

Environmental assessment of heavy metal contamination in bottom sediments of Al-Kharrar lagoon,Rabigh, Red Sea,Saudi Arabia

In order to assess the pollution levels of selected heavy metals, 45 bottom sediment samples were collected from Al-Kharrar lagoon in central western Saudi Arabia. The concentrations of the heavy metals were recorded using inductively coupled plasma-mass spectrometer (ICP-MS). The results showed that the concentrations of Pb and Cd exceeded the environmental background values. However, the heavy metal contents were less than the threshold effect level (TEL) limit. The concentrations of heavy metals in lagoon bottom sediments varied spatially, but their variations showed similar trends. Elevated levels of metals were observed in the northern and southern parts of the lagoon. Evaluation of contamination levels by the sediment quality guidelines (SQG) of the US-EPA revealed that sediments were non-polluted-moderately to heavily polluted with Pb; non-polluted to moderately polluted with Cu; and non-polluted with Mn, Zn, Cd, and Cr. The geoaccumulation index showed that lagoon sediments were unpolluted with Cd, Mn, Fe, Hg, Mo, and Se; unpolluted to moderately polluted with Zn and Co; and moderately polluted with Pb, Cr, Cu, and As. The high enrichment factor values for Pb, As, Cu, Cr, Co, and Zn (>2) indicate their anthropogenic sources, whereas the remaining elements were of natural origins consistent with their low enrichment levels. The values of CF indicate that the bottom sediments of Al-Kharrar lagoon are moderately contaminated with Mn and Pb.     

Heavy metals contents on beach and dune sediments from Espinho to Mondego Cape (Portugal)—influence of human activities

Following previous studies on beach and dune sediments from the Espinho–Mondego Cape coastal sector, geochemical studies have been done on the same sediments aiming to unravel the lithological from the anthropogenic geochemical signal. 129 samples have been collected from 45 profiles, in beach and dune sediments. Total Fe, Cu, Pb, Zn, Mn, Cd, Co, Ni, Cr, Ca, Mg and Al concentrations were measured in the fine fractions of the sediments. The absence of relationship between the analysed heavy elements and Al and the exhibition of contents higher than the rocks outcropping in the hinterland, point to an additional source of heavy metals related to human activities. The available data allowed us to consider that inputs from Aveiro lagoon (natural and anthropogenic), Douro River and coastal erosion (by littoral drift or advective currents) are the main sources of heavy metals in this region.     

Spatio-temporal trends of heavy metals and source apportionment in Tolo Harbour,Hong Kong

This study provided a picture of the spatial and temporal distributions of Cr, Co, Ni Cu, Zn, As, Cd and Pb in bottom sediments of Tolo Harbour. The concentrations of the eight heavy metals differed significantly between sites due to the poor tidal flushing in Tolo Harbour. The levels of Cu, Zn, Cd and Pb were generally enriched in sediments from inner Tolo Harbour, while sediments from outer Tolo Harbour (Tolo Channel) had higher levels of Cr, Co and Ni. The redox sensitive element arsenic showed no distinct spatial pattern in Tolo Harbour. The decreasing levels of Cu, Zn, Pb and Cd in sediments with increasing distance from land demonstrated a typical diffusion pattern from land to the direction of sea. Two hot spots of Cu, Zn, Pb and Cd in sediments were located near Tai Po and Sha Tin new town, indicating that Cu, Zn, Pb and Zn were from land-derived sources. The sites with relatively high levels of Cr, Co and Ni in sediments were located in areas close to waste spoil in sea floor. The natural and anthropogenic inputs from Sha Tin and Tai Po to Tolo Harbour were mostly responsible for Cu, Zn, Cd and Pb enrichment in sediments from inner Tolo Harbour. The waste spoil in sea floor was believed to contribute to the Cr, Co and Ni in outer Tolo Harbour. The results of correlation coefficient between the eight heavy metals showed that Cu, Zn, Cd and Pb were strongly positively correlated, and Cr, Co and Ni were also significantly correlated with each other. The best explanation of strong correlation was their similar source. As, however, is not well correlated with the other seven heavy metals. The average concentrations of Cu and Zn displayed general increasing trends from 1978 to 2006 in Tolo Harbour, while the mean levels of Cr and Pb displayed a substantial decrease from 1978 to 1987, then a slight increase after 1987. No distinct temporal trends of the concentrations of Ni and As were observed from 1978 due to the inconsecutive data. On the other hand, the increasing trends of Cr, Cu, Zn, Cd and Pb were observed since 1996.     

雅鲁藏布江表层沉积物地球化学元素研究

雅鲁藏布江流域还没有大的工业污染源,仍然属于自然河流.对雅鲁藏布江16个表层沉积样品的全样、小于20μm 和小于63μm 粒级的32种元素含量进行了测定,并分析了与人类活动密切相关的元素 Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Cd 和 Pb 的含量分布特征,以及这些元素含量与粒径之间的关系.结果表明,多数元素(Cs 除外)与西藏土壤元素背景值相差不大, B、Cr、Ni、As 和 Cs 含量高于中国陆壳元素丰度值,但这些元素主要来源于该流域富含这些元素的页岩、片岩和千枚岩等母岩.由于相似的地球化学行为,沉积物中 Cr、Mn、Fe、Co、Ni、Cu、Zn 之间显著正相关;除 Pb、As 外,一些元素(如 Zn、Ni)与沉积物的粒径显著负相关     

Geochemistry of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan Province (P. R. China): implications on sources of trace metals

This paper reports a geochemical study of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan province (P. R. China). Trace metals Ba, Bi, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, Sb, Pb, Tl, Th, U, Zr, Hf, Nb and Ta were analyzed using ICP-MS, and Pb isotopes of the bulk sediments were measured by MC-ICP-MS. The results show that trace metals Cd, Bi, Sn, Sc, Cr, Mn, Co, Ni, Cu, Zn, Sb, Pb and Tl are enriched in the sediments. Among these metals, Cd, Bi and Sn are extremely highly enriched (EF values >40), metals Zn, Sn, Sb and Pb significantly highly (5 < EF < 20), and metals Sc, Cr, Mn, Co, Ni, Cu and Tl moderately highly (2 < EF < 5) enriched in the river sediments. All these metals, however, are moderately enriched in the lake sediments. Geochemical results of trace metals Th, Sc, Co, Cr, Zr, Hf and La, and Pb isotopes suggest that metals in the river sediments are of multi-sources, including both natural and anthropogenic sources. Metals of the natural sources might be contributed mostly from weathering of the Indosinian granites (GR) and Palaeozoic sandstones (PL), and metals of anthropogenic sources were contributed from Pb–Zn ore deposits distributed in upper river areas. Metals in the lake sediments consist of the anthropogenic proportions, which were contributed from automobile exhausts and coal dusts. Thus, heavy-metal contamination for the river sediments is attributed to the exploitation and utilization (e.g., mining, smelting, and refining) of Pb–Zn ore mineral resources in the upper river areas, and this for the lake sediments was caused by automobile exhausts and coal combustion. Metals Bi, Cd, Pb, Sn and Sb have anthropogenic proportion of higher than 90%, with natural contribution less than 10%. Metals Mn and Zn consist of anthropogenic proportion of 60–85%, with natural proportion higher than 15%. Metals Sc, Cr, Co, Cu, Tl, Th, U and Ta have anthropogenic proportion of 30–70%, with natural contribution higher than 30%. Metals Ba, V and Mo might be contributed mostly from natural process.     

Concentration distribution and assessment of several heavy metals in sediments of west-four Pearl River Estuary

Grain size parameters, trace metals (Co, Cu, Ni, Pb, Cr, Zn, Ba, Zr and Sr) and total organic matter (TOM) of 38 surficial sediments and a sediment core of west-four Pearl River Estuary region were analyzed. The spacial distribution and the transportation procession of the chemical element in surficial sediments were studied mainly. Multivariate statistics are used to analyses the interrelationship of metal elements, TOM and the grain size parameters. The results demonstrated that terrigenous sediment taken by the rivers are main sources of the trace metal elements and TOM, and the lithology of parent material is a dominating factor controlling the trace metal composition in the surficial sediment. In addition, the hydrodynamic condition and landform are the dominating factors controlling the large-scale distribution, while the anthropogenic input in the coastal area alters the regional distribution of heavy metal elements Co, Cu, Ni, Pb, Cr and Zn. The enrichment factor (EF) analysis was used for the differentiation of the metal source between anthropogenic and naturally occurring, and for the assessment of the anthropogenic influence, the deeper layer content of heavy metals were calculated as the background values and Zr was chosen as the reference element for Co, Cu, Ni, Pb, Cr and Zn. The result indicate prevalent enrichment of Co, Cu, Ni, Pb and Cr, and the contamination of Pb is most obvious, further more, the peculiar high EF value sites of Zn and Pb probably suggest point source input.     

Partitioning,bioavailability and origin of heavy metals from the Nador Lagoon sediments (Morocco) as a basis for their management

Nador Lagoon sediments show low trace element concentrations, and, in relation to the lagoon geochemical baseline, only some anomalies for As, Cd, Cu and Pb in the NW of the lagoon deserve to be outstanding. The distribution of major, minor and trace elements in the lagoon allows a breakdown in four zones. Between “Beni Ensar” and “Atelouane” (zone A), a quite confined zone rich in organic matter and S, the most important trace-element anomalies (As, Cd, Co, Cu, Mn, Pb, Zn) were found, mainly around industry and old mining activities. In the surrounding of the city of Nador (zone B), the anomalies correspond to Mn, Cu and Zn. The coastal barrier and Kebdana channel (zone C) show moderately concentrations of Cd, Cr and Ni at specific sites. The less polluted area is the SE of the lagoon (zone D), with no outstanding anomaly. In lagoon sediments, metal bioavailability is very low. The metal partitioning patterns show that Cu, Pb and Zn present a low availability because they are bounded to the residual, non-mobile phases of the sediments. Only in some sites, the fraction was associated with organic matter, which could be liberated easily. Arsenic is concentrated in both the residual phases and the organic matter, the latter being more available. Cadmium is mainly concentrated in some samples in the interchangeable fraction, which could be considered as a potentially toxic element because it is easily released. Concerning the origin of these trace elements, those found in zone A correspond mostly to a natural source by weathering of mount Gourougou volcanic rocks (As, Co, Cu, Pb and Zn), and to an anthropogenic origin (Cd) owing to the presence of industry and old mines. In zone B, contributions of Cu and Zn enter the lagoon through soil weathering and river-borne, and as anthropogenic pollution from urban wastes. In zone C the most important pollutant is Cd deduced to be of anthropogenic origin from the close industry and intensive agriculture area. In spite of the intense socio-economic activities developed in the Nador Lagoon (agriculture, industry, fishing, tourism) trace element concentrations in the sediments are low and with scarce bioavailability. Only the NW sector is relativity polluted because of geogenic features.     

Heavy metal history from cores in Wellington Harbour,New Zealand

Analysis of ten heavy metals (Ag, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Zn) in six sediment cores from Wellington Harbour show both anthropogenic enrichments and diagenetic modifications. Absolute concentrations determined by two methods, x-ray fluorescence and acid leaching for bioavailability, are not comparable. However, vertical trends in concentrations of the cored sediment are comparable. To assess levels of anthropogenic pollution, enrichment factors (enriched concentrations in upper core divided by background levels in lower core) are preferred over index of accumulation (I _geo) values because preindustrial or background levels of heavy metals are well constrained. The ten metals are placed into three groups: (1) Cu, Pb, and Zn, which show the most anthropogenic enrichment; (2) As, Cd, Cr, Ni, and Sb, which are often associated with anthropogenic pollution but show only minor enrichment; and (3) Fe and Mn, which are diagenetically enriched. Assuming harbor waters are well mixed, anthropogenic enrichments of Cu, Pb, and Zn, are time correlative, but the degree of enrichment depends on the method of analysis and core location. Levels of As, Cd, Pb, and Zn show small variations in preindustrial sediments that are not related to changes in grain size and probably result from changes in the oxidation-reduction potential of the sediments and salinity of the pore waters.     

Comparative study of As,Cd, Cu,Cr, Mg,Mn, Ni,Pb and Zn concentrations between sediment and water from estuary and port

The contents of As, Cd, Cu, Cr, Mg, Mn, Ni, Pb and Zn have been determined in sediment and water samples from Valle de las Garzas estuary and Port Manzanillo (Colima, Mexico) using ICP-AES. The concentrations of these elements were used for a comparative study to determine the distribution of heavy metals and to evaluate which elements reflect natural or anthropogenic backgrounds. For this purpose, seven sampling points were selected: Four of them correspond to the lagoon, and three were situated in the port. Statistical analysis of the mineral content was assessed. Initially, data comparison was assessed by statistical tests for each variable. Principal component analysis was then applied considering the influence of all variables at the same time by obtaining the distribution of samples according to their scores in the principal component space. In this way, four studies were carried out: (1) study of sediments collected during the dry season; (2) study of sediments collected during the rainy season; (3) comparative study between sediments from rainy and dry season; and (4) study of water composition collected during rainy season. From the results of the performed analyses, it can be concluded that metals distribution pattern reflected natural and anthropogenic backgrounds (e.g., sediments from the lagoon, situated at the beginning of the rain channel, presented high contents of Zn and Cu, perhaps related to anthropogenic activities or the influence of igneous sediments).     

Trace element distributions in surficial sediments of the northern Tyrrhenian Sea: Contribution to heavy-metal pollution assessment

The trace element distributions in surficial sediment of Tyrrhenian Sea have been investigated as a part of a series of studies on the environmental quality of the area off the Tuscany coast (west-central Italy). This research has focused on the presence of possible contaminated zones; it also provides data for the identification and future monitoring and control of pollution sources. The study of numerous surface sediments and core samples has made it possible to distinguish between heavy-metal enrichments related to natural sources and other anomalies caused by anthropogenic contamination. Over much of the basin, the surface Pb, Cu, Zn, and As contents appear considerably enriched relative to those below 15 cm; among these metals, Pb shows the highest and most widespread enrichment. Only in the case of some coarse-grained sediments close to the mouth of Cecina River it is possible to relate anomalously high Zn contents to natural sources. In all other sampling stations, the enrichments of Pb, Cu, Zn, and As are ascribed to man's influence. The sediment distributions of Co, Cr, and Ni do not seem to be related to anthropogenic activities; rather they mirror influx of materials derived from sources of ophiolitic rock. The distribution of barium shows only two significant positive anomalies, and both are related to natural causes. Concentrations of vanadium are high in a zone close to an important smelting plant; these are thought to be of anthropogenic origin.     

A geological interpretation of heavy metal concentrations in soils and sediments in the southern Netherlands

The natural variation in heavy metal contents of subsurface sediments in the southern Netherlands is described, based on a series of 820 bulk geochemical analyses. The detrital heavy metal contents of these sediments show linear correlations with Al as a result of their joint occurrence in phyllosilicates. Anomalous enrichments occur as a result of the presence of glauconite (As, Cr, Ni, Pb, Zn), pyrite (As) or Fe-oxides (As, Ba, Ni, Zn), due to the interaction of organic-rich subsurface material with groundwater (Co, Ni, Zn) or as a result of anthropogenic pollution in topsoils (Cu, Pb, Zn). The contents of Al, Fe, K and S are well suited to determine background values, and to identify the cause for anomalous accumulations of heavy metals.     

The sources of metal contents in the shelf sediments from the Marmara Sea, Turkey

The shelf area is the largest morphological unit of the Marmara Sea and is subjected to increasing population, urbanization, and industrial activities. Metal contents (Al, Fe, Mn, Cu, Pb, Zn, Ni, Cr, Co and Hg) of the surface sediments from the shelf areas of the Marmara Sea generally do not indicate shelf-wide pollution. The variability of the metal contents of the shelf sediments is mainly governed by the geochemical differences in the northern and southern hinterlands. Northern shelf sediments contain lower values compared to those of the southern shelf, where higher Ni, Cr, Pb, Cu and Zn are derived from the rock formations and mineralized zones. However, besides from the natural high background in the southern shelf, some anthropogenic influences are evident from EF values of Pb, Zn and Cu, and also from their high mobility in the semi-isolated bay sediments. Anthropogenic influences are found to be limited at the confluence of Istanbul Strait in the northern shelf. However, suspended sediments along the shallow parts of the northern shelf were found to be enriched in Pb and Hg and to a lesser degree in Zn, reflecting anthropogenic inputs from Istanbul Metropolitan and possibly from the Black Sea via the Istanbul Strait.     

Heavy metal distribution in sediments from Calabar River, southeastern Nigeria

The concentration and areal distribution of selected metals (Pb, Zn, Cu, Cd, Ni, Fe, and Cr) in the sediments of the Calabar River were studied to determine the extent of anthropogenic input and to estimate the effects of dumping industrial waste materials into the river. The concentrations of Pb, Zn, and Cu indicate relatively moderate pollution mainly on the left-hand side of the river while Ni, Cr, Co, Cd, and Fe levels are below values found to have adverse effects on the lives of marine biota. High metal contents are found close to industrial establishments and so enhanced metal concentrations are related to industrial sewage and metal leaching from garbage and solid waste dumps.     

Assessment of trace element geochemistry of Hampton Roads harbor and lower Chesapeake Bay area sediments

Acid extractable Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb. and Zn were determined in sediments from the Inner Virginia Shelf, and from shipping channels in the lower Chesapeake Bay and Hampton Roads, Virginia, harbor system. Data were evaluated by a variety of techniques Levels of Cd, Cu, Pb, and Zn exceeded average crustal abundances for most of the study sites. Cumulative frequency curves suggested that there were two major populations for all metals and perhaps a third and smaller, one for Cd, Cr, and Mn Plots of metal vs Fe indicated no anthropogenic inputs of metals for shelf and Chesapeake Bay channel sites, but suggested anthropogenic influences for all metals in several of the inshore sites. Enrichment factor calculations showed enrichment of Cd, Pb, and Zn with respect to average crustal abundances for all sites and of Cu for the industrial harbor system. A recommendation of this study for evaluation of environmental geochemical metals data is to utilize mean concentrations, cumulative frequency plots, and metal vs Fe and/or enrichment factor calculations when evaluating the pollution status of sediments.     

Multivariate statistical techniques for evaluating and identifying the environmental significance of heavy metal contamination in sediments of the Yangtze River, China

The concentrations of heavy metals (Cr, Co, Ni, Cu, Zn, Pb, Cd, As, Hg, and Fe) in sediments of the Yangtze River, China, were investigated to evaluate levels of contamination and their potential sources. The lowest heavy metal concentrations were found in the source regions of the river basin. Relatively high concentrations of metals, except Cr, were found in the Sichuan Basin, and the highest concentrations were in the Xiangjiang and Shun’anhe rivers. All concentrations, except Ni, were higher than global averages. Principal component analysis and hierarchical cluster analysis showed that Zn, Pb, As, Hg, and Cd were derived mainly from the exploitation of various multi-metal minerals, industrial wastewater, and domestic sewage. Cu, Co, and Fe were derived mainly from natural weathering (erosion). Cr and Ni were derived mainly from agricultural activities, municipal and industrial wastewater. Sediment pollution was assessed using the geoaccumulation index (I _geo) and enrichment factor (EF). Among the ten heavy metals assessed, Cd and Pb had the highest I _geo values, followed by Cu, As, Zn, and Hg. The I _geo values of Fe, Cr, Co, and Ni were <0 in all sediments. EF provided similar information to I _geo: no enrichment was found for Cr, Co, and Ni. Cu, Zn, As, and Hg were relatively enriched at some sites while Cd and Pb showed significant enrichment.     

Distribution and immobilization of heavy metals in Pliocene aquifer sediments in Wadi El Natrun depression, Western Desert

The Pliocene aquifer receives inflow of Miocene and Pleistocene aquifer waters in Wadi El Natrun depression. The aquifer also receives inflow from the agricultural activity and septic tanks. Nine sediment samples were collected from the Pliocene aquifer in Wadi E1 Natrun. Heavy metal (Cu, Sr, Zn, Mn, Fe, Al, Ba, Cr, Ni, V, Cd, Co, Mo, and Pb) concentrations of Pliocene aquifer sediments were investigated in bulk, sand, and mud fractions. The determination of extractable trace metals (Cu, Zn, Fe, Mn, and Pb) in Pliocene aquifer sediments using sequential extraction procedure (four steps) has been performed in order to study environmental pathways (e.g., mobility of metals, bounding states). These employ a series of successively stronger chemical leaching reagents which nominally target the different compositional fractions. By analyzing the liquid leachates and the residual solid components, it is possible to determine not only the type and concentration of metals retained in each phase but also their potential ecological significance. Cu, Sr, Zn, Mn, Fe, and Al concentrations are higher in finer sediments than in coarser sediments, while Ba, Cr, Ni, V, Cd, Co, Mo, and Pb are enriched in the coarser fraction. The differences in relative concentrations are attributed to intense anthropogenic inputs from different sources. Heavy metal concentrations are higher than global average concentrations in sandstone, USEPA guidelines, and other local and international aquifer sediments. The order of trace elements in the bulk Pliocene aquifer sediments, from high to low concentrations, is Fe?>?Al?>?Mn?>?Cr?>?Zn?>?Cu?>?Ni?>?V?>?Sr?>?Ba?>?Pb?>?Mo?>?Cd?>?Co. The Pliocene aquifer sediments are highly contaminated for most toxic metals, except Pb and Co which have moderate contamination. The active soluble (F0) and exchangeable (F1) phases are represented by high concentrations of Cu, Zn, Fe, and Mn and relatively higher concentrations of Pb and Cd. This may be due to the increase of silt and clay fractions (mud) in sediments, which act as an adsorbent, retaining metals through ion exchange and other processes. The order of mobility of heavy metals in this phase is found to be Pb?>?Cd?>?Zn?>?Cu?>?Fe?>?Mn. The values of the active phase of most heavy metals are relatively high, indicating that Pliocene sediments are potentially a major sink for heavy metals characterized by high mobility and bioavailability. Fe–Mn oxyhydroxide phase is the most important fraction among labile fractions and represents 22% for Cd, 20% for Fe, 11% for Zn, 8% for Cu, 5% for Pb, and 3% for Mn. The organic matter-bound fraction contains 80% of Mn, 72% of Cu, 68% of Zn, 60% of Fe, 35% of Pb, and 30% of Cd (as mean). Summarizing the sequential extraction, a very good immobilization of the heavy metals by the organic matter-bound fraction is followed by the carbonate-exchangeable-bound fraction. The mobility of the Cd metal in the active and Fe–Mn oxyhydroxide phases is the highest, while the Mn metal had the lowest mobility.     

Trace metals in acid sediments and waters, Pimpama catchment, southeast Queensland, Australia

The Pimpama River floodplain has developed over the last several thousand years as a result of sea-level fluctuations that shaped the lower catchment and enabled the formation of sedimentary pyrite. The subsequent production of sulfuric acid due to the oxidation of this pyrite enhances the breakdown of metal-bearing sediments and can lead to leaching of major and trace metals into the waters of the region. The seasonal pattern of rainfall and current land-use activities are important aspects that intensify the natural production of acid and influence the release and distribution of metals. To identify the source and migration of metals in the Pimpama catchment and to understand the impact of pyrite oxidation on the distribution of metals in sediments and waters, several components of the drainage system were analyzed: bedrock, sediments from river bed and bank, and water. The elements analyzed in this study (V, Cr, Co, Ni, Cu, Zn and Pb) are all present in the bedrock material which explains their occurrence in the unconsolidated sediments of the floodplain. These metals concentrate in the upper section of the sedimentary sequence and their presence is related to clay minerals such as smectite, organic matter and iron phases. However, Zn, Mo and Co occur in higher amounts than the local background and within standard shale. This comparison suggests that the diagenetic processes alone cannot explain the higher concentrations and it is concluded that these metals also have an anthropogenic source. The formation of sulfuric acid creates conditions for higher mobility of some metals, such as Cr, Co, Ni, Cu, Zn, but does not affect less mobile ones such as Mo and Pb. Over the longterm, the production of acid influences the breakdown of mineral phases and enhances the process of weathering. Over the short term, every rain event leaches acid from sediments and mobilizes metals resulting in a substantial reduction in the quality of river water. Received: 2 October 1998 · Accepted: 16 February 1999     

Partitioning of heavy metals in surface Black Sea sediments

Bulk heavy metal (Fe, Mn, Co, Cr, Ni, Cu, Zn and Pb) distributions and their chemical partitioning, together with TOC and carbonate data, were studied in oxic to anoxic surface sediments (0–2 cm) obtained at 18 stations throughout the Black Sea. TOC and carbonate contents, and available hydrographic data, indicate biogenic organic matter produced in shallower waters is transported and buried in the deeper waters of the Black Sea. Bulk metal concentrations measured in the sediments can be related to their geochemical cycles and the geology of the surrounding Black Sea region. Somewhat high Cr and Ni contents in the sediments are interpreted to reflect, in part, the weathering of basic-ultrabasic rocks on the Turkish mainland. Maximum carbonate-free levels of Mn (4347 ppm), Ni (355 ppm) and Co (64 ppm) obtained for sediment from the shallow-water station (102 m) probably result from redox cycling at the socalled ‘Mn pump zone’ where scavenging-precipitation processes of Mn prevail. Chemical partitioning of the heavy metals revealed that Cu, Cr and Fe seem to be significantly bound to the detrital phases whereas carbonate phases tend to hold considerable amounts of Mn and Pb. The sequential extraction procedures used in this study also show that the metals Fe, Co, Ni, Cu, Zn and Pb associated with the ‘oxidizable phases’ are in far greater concentrations than the occurrences of these metals with detrital and carbonate phases. These results are in good agreement with the recent studies on suspended matter and thermodynamic calculations which have revealed that organic compounds and sulfides are the major metal carriers in the anoxic Black Sea basin, whereas Fe-Mn oxyhydroxides can also be important phases of other metals, especially at oxic sites. This study shows that, if used with a suitable combination of the various sequential extraction techniques, metal partitioning can provide important information on the varying geological sources and modes of occurrence and distribution of heavy metals in sediments, as well as, on the physical and chemical conditions prevailing in an anoxic marine environment.     

Status of anthropogenically induced metal pollution in the Kanpur-Unnao industrial region of the Ganga Plain, India

 The Ganga Plain is one of the most densely populated regions and one of the largest groundwater repositories of the Earth. For several decades, the drainage basin of the Ganga Plain has been used for the disposal of domestic and industrial wastes which has adversely affected the quality of water, sediments and agricultural soils of the plain. The concentrations of Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sn, Zn and organic carbon were determined in river sediments and soils of the Ganga Plain in the Kanpur-Unnao industrial region in 1994 and 1995 (pre-monsoon period of April–May). High contents (maximum values) of C-org (12.0 wt. %), Cr (3.40 wt. %), Sn (1.92 wt. %), Zn (4000 mg/kg), Pb (646 mg/kg), Cu (408 mg/kg), Ni (502 mg/kg) and Cd (9.8 mg/kg) in sediments (<20 μm fraction); and C-org (5.9 wt. %), Cr (2.16 wt. %), Sn (1.21 wt %), Zn (975 mg/kg) and Ni (482 mg/kg) in soils (<20 μm) in the pre-monsoon period of 1994 were found. From 1994 to 1995 the contents of Fe and Sn in sediments increase whereas those of C-org, Cd, Cu, Ni and Zn decrease. Considering the analytical errors, Al, Co, Cr, Mn and Pb do not show any change in their concentrations. In soils, the contents of Cd, Fe and Sn increase whereas those of Ni decrease from 1994 to 1995. Aluminium, Co, Cr, Cu, Mn, Pb and Zn do not show any change in their concentrations from 1994 to 1995. About 90% of the contents of Cd, Cr and Sn; 50–75% of C-org, Cu and Zn; and 25% of Co, Ni and Pb in sediments are derived from the anthropogenic input in relation to the natural background values, whereas in soils this is the case for about 90% of Cr and Sn; about 75% of Cd; and about 25% of C-org, Cu, Ni and Zn. The sediments of the study area show enrichment factors of 23.6 for Cr, 14.7 for Cd, 12.2 for Sn, 3.6 for C-org, 3.2 for Zn, 2.6 for Cu and 1.6 for Ni. The soils are enriched with factors of 10.7 for Cr, 9.0 for Sn, 3.6 for Cd, 1.8 for Ni and 1.5 for Cu and Zn, respectively. Received: 3 March 1998 · Accepted: 15 June 1998