Contaminated sediments as a potential source of Zn, Pb, and Cd for a river system in the historical metalliferous ore mining and smelting industry area of South Poland

Background, aim, and scope  Elevated levels of heavy metals in the aquatic and soil systems can be caused by the weathering of mineralized rocks. This enrichment is often considerably enlarged by historical and current mining and smelting activities. In Poland, the most contaminated river systems are those in the Silesia region. The metalliferous ore mining and smelting industries have been the main sources of heavy metal pollutions over the last 100–170 years. The previous and present studies have shown very high concentrations of heavy metals in the bottom sediments of the Mala Panew River, the most polluted tributary of the Oder River. The main objective of this work was to study temporary changes of selected metal (Zn, Pb, and Cd) concentrations in upper layer of bottom sediments at the measuring point near the outlet of the Mala Panew River into the Oder River, and to determine the vertical distribution of the metals in the sediment cores from the most polluted middle part of this river. The mobility of the metals and their potential bioavailability were assessed based on metal partitioning in the sediments and metal concentrations in pore waters. The presented data were compared with metal concentrations in aquatic sediments from similar historical mining and smelting sites in Poland and other countries. Methods  The upper layer of bottom sediment samples from the same Mala Panew River measuring point were collected six times in the period 1997–2005, while five sediment cores were collected once from the middle course of Mala Panew River in 2006. Abiotic parameters such as pH and Eh have been determined in situ. Metal contents were determined in the <20 and <63 μm size fractions of sediments after digestion in a microwave oven with aqua regia or concentrated nitric acid. Metal mobility was assessed in the selected sediment cores by the chemical forms of metals (sequential extraction method) and their concentrations in pore waters were investigated. Results  The concentrations of Cd, Pb, and Zn in the upper layer of sediments varied, depending on both the season and the year of sampling. Their mean concentrations (from six samplings) are [mg/kg]: Zn 1,846, Pb 229 and Cd 73. The metal concentrations in the sediment cores varied with the depth in the range of [mg/kg]: 0.18–559 for Cd, 26.2–3,309 for Pb and 126–11,153 for Zn, although the highest accumulations generally could be observed in the deeper layers. The most mobile metal fractions, i.e., exchangeable, carbonate and easily reducible fractions, are typical of Zn and Cd. Cadmium was found to be the most mobile metal and its relative contribution ranges from 84 to 96%, while in the case of Zn it ranged from 45 to 94%. Lead is mainly associated with the moderately reducible fraction (30–60%). Relative contributions of metal chemical forms slightly vary with the depth in the sediment profile. The results obtained for the pore water samples show very high concentrations of the metals studied, especially in the case of Cd (31–960 μg/dm³) and Zn (300–4,400 μg/dm³). Discussion  Accumulation of Cd, Pb, and Zn in the upper layer of the bottom sediments and in the sediment core samples from the Mala Panew River is very high, considerably exceeding the local geochemical background. High contributions of mobile Cd and Zn and the toxicity of cadmium can cause environmental risk. Our measurements also suggest that mobile metals can migrate into groundwater, whereas the groundwater itself can leach some chemicals from river sediments, because of a relatively high water table in the study area, especially during rainfall periods. Comparison of the results obtained with the literature data from the last decade shows that the concentrations of Cd and Zn in the sediments from the Mala Panew River are the highest among other submersed sediments in Poland and other regions (e.g., the Mulde River, Germany). Conclusions  The Mala Panew River is one of the most polluted rivers when compared with similar historical mining and smelting areas in Poland and elsewhere. The sediments studied are strongly polluted with the metals analyzed. In the upper layer of the bottom sediments there has been no reduction of Zn and Cd amounts over the last decade, which could suggests a long-term migration and a secondary contamination. Considerably higher accumulations of metals in overbank sediment cores and in the deeper core section could result from strong contamination in previous decades and translocation of Cd and Zn (secondary pollutants). The relatively high concentrations of the two metals in pore waters support these findings. Cadmium is crucial in the environmental risk assessment because of its high mobility and toxicity. These data are important for water/sediment management in the transboundary Oder River catchment, situated in Poland, Germany and the Czech Republic. Recommendations and perspectives  It is important to assess mobility phase and pore water in the contaminated historical aquatic sediments. Such studies may help explain the changes, which take place in the sediment layers as well as at the water–sediment interface. Obtained results should be used for the risk assessment of the historical contaminated sediments at the local river-basin scale. The treatment of contaminated sediments, e.g., dragging activity, should be considered as very important in management strategies in order to avoid remobilization of metals.     

巢湖表层沉积物中重金属的分布及污染评价

对巢湖湖区不同位点的表层沉积物中的Fe、Cr、Pb、Cu、Co、Zn、Ni7种重金属含量进行的分析表明,湖泊沉积物中重金属含量分布呈现一定的区域特征,由于巢湖西半湖靠近合肥市区,大量的工业废水和生活污水通过河道排入巢湖,引起西半湖区中重金属含量高于东半湖区。采用富集因子法和地积累指数法对巢湖沉积物重金属污染现状进行了评价,结果表明,巢湖沉积物中存在Pb、Cu污染,个别地区已相当严重,并呈现沿湖心区至东半湖区逐渐降低趋势。研究表明,两种方法均能对人为污染行为做出较为科学的评价,且两种方法得到的评价结果基本一致。由于重金属元素有很强的毒性,并且能够在食物链中传递,有关部门应及早从流域环境综合规划入手,对重金属污染问题采取有力的控制对策,保护沿湖地区居民免受危害。此外,对巢湖表层沉积物中重金属污染物来源进行了初步分析,据分析结果判断,巢湖沉积物中重金属总量Co、Fe、Cr的来源相似,Zn和Cu的来源相似。     

Thirty Years of Chemical Changes in Alpine Acid-Sensitive Lakes in the Alps

The Pennask Creek watershed in British Columbia (BC), Canada has been contaminated with acid rock drainage (ARD) and associated metal leaching (ML) as a result of highway construction. By combining existing and newly gathered information, this study determined the extent of metal contamination of the water and sediments, the potential biological impacts of this contamination, the influence of local geology, and estimated the potential risk to aquatic organisms. Surface water and sediment samples from the watershed were analyzed for general chemical parameters and trace metals. Rock samples were analyzed for mineralogy and chemical composition. Metal concentrations in water and sediments downstream of the ARD/ML source were higher than elsewhere in the watershed. Metals of concern include aluminum (Al), copper (Cu), and zinc (Zn). Analysis of historical water quality data indicated that the concentrations of these metals have decreased markedly since 2004, due to remediation efforts. Rock samples collected from the streambeds and banks were not found to be potentially acid generating, but did contain significant levels of metals. Al, Cu, and Zn levels consistently exceeded BC water and sediment quality guidelines for the protection of aquatic life, indicating that adverse biological effects are probable at stations downstream of the ARD/ML source. Benthic invertebrate monitoring over a 10-year period showed low abundance and diversity and a complete absence of sensitive taxa at downstream stations. Risk quotients indicated a likelihood of adverse biological effects for aquatic organisms, including rainbow trout, due to metal contamination in the watershed.     

Trace metal behaviour during summer in a stratified Mediterranean system: The Louros Estuary (Greece)

Trace metals (Al, Pb, Zn, Cr, Cu, Ni, Fe, Mn) were studied in waters (dissolved and particulate phases) and sediments of the Louros Estuary in the Amvrakikos Gulf, one of the most important European wetlands located at the NW coast of Greece. The study system is small, with a relatively narrow mixing zone, typical for Mediterranean estuaries. Particular emphasis was given to understanding the conditions prevailing in summer. During this season saline water intrudes the estuary along the river bed, despite the existing shallow sill, and forms a thin salt-wedge water mass, which occupies the near bottom layer with its thin end pointed upstream. Particulate metal concentrations within this saline bottom layer are considerably higher than in the riverine and marine sections of the estuary. Since the metal content of particles collected upstream is higher than that of the marine ones, there is a clear evidence that the salt-wedge acts as a ‘sink’ for most metals during the summer. Coexistance in the same zone of high dissolved metal concentrations indicate that loosely associated metals are desorbed from riverine particles, whereas newly formed suspended matter is deposited together with particles, transported by the river. The accumulation of metals in the near bottom layer affects directly their distribution in the sediments. The maximum concentrations of the metal fraction which is loosely held in sediments, are found primarily at the same site. The distribution of the ‘non-labile’ metal fraction of the sediments (particularly for Cu and Pb) is broadly constant throughout the estuary, confirming the absence of any significant natural or industrial point sources, at the lower part of the river. However, the analysis of sediment cores reveals an enrichment of this metal fraction at the top, near surface sections of the mouth area, indicating relatively recent pollution.     

Distribution of Trace Metals and Organic Matter in the Sediments of Godavari Estuary of Kakinada Bay, East Coast of India

In Godavari estuary, the enhanced metal concentration in the sediment is localized, and is accompanied by marked enrichment in organic carbon, Kjeldahl nitrogen, and humic acid. High concentration of organic carbon was observed near the riverside sampling stations. A similar pattern was found for the humic acid concentrations. Relatively high organic carbon content was observed in pre-monsoon/monsoon compared to post-monsoon seasons which can be attributed to higher productivity due to upwelling in the former and landrunoff due to excessive rainfall in the later seasons. The trace metals in the sediments were found to be in the following order of their abundanceFe≥Mn≥Zn≥Pb≥Ni≥Cu≥Cd. In monsoon season relatively high levels of trace metals were reported in surface sediments which are transported by currents. The dominant process controllingthe metal enrichment may be either precipitation of metal-humic acid type of complexes. Our results indicate that in the Godavari estuary, the metal distribution is mainly influenced by sedimentarydynamics, while the contamination effect is very limited.     

Geochemical Mobility and Bioavailability of Heavy Metals in a Lake Affected by Acid Mine Drainage: Lake Hope, Vinton County, Ohio

Sandy Run (Vinton County, southeastern Ohio, USA) is a stream receiving acid mine drainage (AMD) from an abandoned coal mine complex. This stream has been dammed to form Lake Hope. The heavy metal composition of waters (benthic and pore), sediments, and macroinvertebrates in the lake reservoir sediments were analyzed. Lake waters contained Mn as the heavy metal present in higher concentrations followed by Fe, Al, and Zn. Depletion of Fe and Al occurred from precipitation of less soluble Fe and Al oxides and hydroxides along Sandy Run before entering the lake, producing a high Mn water input into the reservoir. Concentrations of heavy metals in the sediments increased toward the dam area. Sequential extraction of metals in the sediments showed that the highest fractions of metals corresponded to the detrital fraction or eroded material from the watershed and metals associated with iron and manganese hydroxides. Heavy metals in the organic sediment fraction were low. Heavy metals from the AMD source, as well as sediments rich in heavy metals eroded from the watershed, were transported to the downstream dam area and stored at the bottom, producing the observed chemistry. Heavy metals in benthic waters also were sourced from the diffusion of ions from sediments and lake waters as variation in pH and redox conditions determined the flux at the sediment–water interface. Metal concentrations were measured within two deposit feeders, oligochaetes and chironomids, and compared to trends in physical metal concentration across the lake. For the four heavy metals with higher concentration in both benthic animals, the concentrations followed the trend: Fe?>?Al?>?Mn?>?Zn, which were similar to the bioavailable metals in the sediments rather than the pore or the benthic water where Mn was the most abundant heavy metal. Ingestion of sediment, not exposure to pore or benthic waters, appeared to be the main transfer mechanism for metals into the biota. Trends and patterns in animal metal concentrations across the lake were probably a complex process controlled by metabolic needs and metallic regulation and tolerance. Even when Mn was the highest concentration heavy metal in the pore waters, it was the lowest to bioconcentrate in the organisms. In comparison, Cd, the lowest concentration metal in the sediments, presented one of the highest bioaccumulation factors.     

Distinguishing regional and local sources of pollution by trace metals and magnetic particles in fluvial sediments of the Morava River, Czech Republic

Purpose

Regional contamination of southern Moravia (SE part of the Czech Republic) by trace metals and magnetic particles during the twentieth century was quantified in fluvial sediments of the Morava River. The influence of local pollution sources on regional contamination of the river sediments and the effect of sampling site heterogeneity were studied in sediment profiles with different lithologies.

Materials and methods

Hundreds of sediment samples were obtained from regulated channel banks and naturally inundated floodplains and proxy elemental analyses were carried out by energy dispersive X-ray fluorescence spectroscopy (ED XRF) and further calibrated by inductively coupled plasma mass spectrometry (ICP MS). Magnetic susceptibility was determined as a proxy for industrial contamination. The age model for the floodplain sediments was established from ¹³⁷Cs and ²¹⁰Pb dating. Trace metal contamination was assessed by establishing the lithological background values from floodplain profiles and calculating enrichment factors (EF) of trace metals (i.e. Pb, Zn, Cu) and magnetic susceptibility for the entire study area.

Results and discussion

Channel sediments are unsuitable for the reconstruction of historical regional contamination due to their lithological heterogeneity and the “chaotic” influence of local sources of contamination, as well as the possibility of geochemical mobility of pollutants. On the other hand, sediments from regulated river banks qualitatively reflected the actual, local contamination of the river system.

Conclusions

This approach allowed us to distinguish the influence of local sources of contamination by comparison with more spatially averaged contamination signals from distal floodplain profiles. The studied area is weakly contaminated (EF ～1–2), while individual sediment strata from regulated channel banks reflect local sources of contamination and contain up to several times higher concentrations of trace metals.     

Distribution of Heavy Metals in Near-Shore Sediments of the Swan River Estuary,Western Australia

Estuarine systems adjacent to urban areas are at risk of contamination by contaminants from anthropogenic sources, such as heavy metals. We anticipated that the sediments of the Swan River estuary, which runs through metropolitan Perth in Western Australia, would show metal contamination related to industrialization and inputs of stormwater. Total Cu, Pb and Cd concentrations, and Cu, Pb, Cr and Zn inoperationally-defined fractions, were determined inseparate sampling exercises in near-shore sediments ofthe upper Swan River estuary.Total metal concentrations in sediments were not high (maximum values of 297 mg kg^-1 for Cu, 184 mg kg^-1 for Pb and 0.9 mg kg^-1 for Cd) when compared with Australian environmental assessmentguidelines for soils. On the basis of linear regressions between sediment metal concentrations andphysicochemical properties of the sediments (pH, organic carbon, particle size distribution), no single parameter could explain the variation in metal concentrations for all metals. Sediment organic carbon content was positively correlated with Cu concentration; Cu concentrations also increased significantly with increasing clay content anddecreasing sand content. Pb concentrations showed a significant increase with increasing sediment pH, and were approximately three-fold higher in sediments adjacent to stormwater drain outfalls than in sediments remote from drains; no such effect was observed for Cu or Cd. No effect of distance downstream was observed. Sequential extraction of sediments showed that most of the metals were in relatively immobile forms, for example bound to Feoxides, or only extractable by aqua regia. The enhanced concentrations of Pb near stormwater outfalls suggest that vehicle-derived Pb may be an important contributor of Pb to the estuary.     

Estimation of Source of Heavy Metal Contamination in Sediments of Gomti River (India) using Principal Component Analysis

This study explores the extent and possible sources of heavy metal (Cd, Cr, Cu, Fe, Mn, Pb, Zn and Ni) contamination in the bed sediments of the Gomti River performing principal component analysis on the five years (Jan. 1994–Dec. 1998) data set obtained through continuous monitoring of the river water and bed sediments at eight selected sites and water/wastewater of its tributaries/drains. Influence of anthropogenic activities on metal contamination of the bed sediments was evaluated through computing the geoaccumulation index for various metals at studied sites. PCA performed on combined (river bed sediment, water, suspended solids, water/wastewater from tributaries/drains) data set extracted two significant factors explaining more than 58% of total variance. Factor loadings suggested the presence of both natural as well as anthropogenic sources for all these metals in the river bed sediments. Among all the sites, the sites 4 and 5 are more contaminated with Cd, Cu, Cr and Pb, which was supported by the geoaccumulation indices computed for metals. Factor scores revealed presence of seasonal (monsoon-related) differences in metals profiles for river water and suspended solids and absence of seasonal differences for bed sediment and wastewater. Further, the metal contamination of the bed sediment was also evaluated using biological thresholds. Results suggested that the river bed sediments are contaminated with heavy metals, which may contribute to sediment toxicity to the freshwater ecosystem of the Gomti River.     

Anthropogenic heavy metal inputs to lowland river systems,a case study. The River Stour,U.K.

Surface waters, sediments and interstitial waters were collected from 9 sites of the River Stour, UK, during June 1987. The aim was to identify the sources of EC List I (Hg, Cd) and List II (As, Cr, Cu, Ni, Pb, Zn) metals and metalloids to this lowland river system and to assess the magnitude of metal enrichment. The study reach spanned some 60 km, traversing rural and urban landscapes. Results indicate that the larger municipal sewage treatment works (STW), which receive industrial effluents, were the major source of metals, but smaller rural works also exerted some contaminative influences. Metal concentrations in bottom sediments, displayed 2–11 fold increases over catchment background levels with maximum loadings coinciding with discharges from the Great Cornard and Sudbury STWs. Elevations in water column metal concentrations were also apparent downstream of point source inputs, but concentrations were consistently below designated ‘Water Quality Standards’. Distance from the point source, sediment texture and hydrology appeared to be the main factors responsible for the observed distribution of metals within this river system.     

Mapping the Distribution of the Bioaccessible Fraction of Trace Metals in the Sediments of an Urban Stream,Park River Watershed,Connecticut

The Park River watershed (PRW), a sub-basin of the Lower Connecticut River watershed, has experienced increased urbanization over the last century as the city of Hartford and its surrounding towns have grown and developed. We present watershed-wide and outflow scale maps of the trace metals Cd, Cu, Zn, and Pb to determine patterns of contamination in fine (<63 μm) stream sediment. Results are compared to established sediment quality guidelines (SQG) and probable effect concentrations (PEC) for each metal. Throughout the watershed, higher concentrations of trace metals are observed in the more urbanized south branch of the PRW. In this sub-basin, there are more industries that use, and waste, metals in their manufacturing processes that contribute to acutely high concentrations of metals in the fine bedload sediments. Impervious surfaces are examined as well in the context of the entire watershed. While an increase in metals can be attributed to an increase in impervious surfaces, these increases do not generally exceed SQGs and PECs. Two focused mapping studies were conducted at the storm water outflow of the West Hartford Landfill and the Trout Brook Sanitary Sewer Overflow (SSO). The purpose of these studies was to analyze the local effects of natural stream features such as channel bar deposits next to the outfalls. We determined that the sediment directly below the two outfalls often exceeded the PEC, while the accumulated sediment around the channel bar deposits was not contaminated beyond background stream levels. We believe mapping at both the small (watershed) and large (outfall) scale can be helpful in future urban studies to determine the extent of trace metal sediment contamination in both channelized and natural sections and may provide a useful method for sediment mitigation endeavors.

     

Heavy metals in tropical Lake Kariba,Zimbabwe

Metal mining is carried out in the drainage basin of Lake Kariba, Zimbabwe. In an attempt to assess the distribution of heavy metals in the lake ecosystem, the concentrations of chromium (Cr), cadmium (Cd), copper (Cu), lead (Pb), manganese (Mn), nickel (Ni), zinc (Zn), and selenium (Se) were analysed in the following ecosystem components at different locations in the lake; water, sediment, aquatic macrophytes, mussels, and carnivorous and herbivorous fish. Concentrations were generally in the same range as in other temperate and tropical aquatic ecosystems, except for Pb and Cd, which were higher in marcrophytes and fish from the lake. Apart from Cd, there were no signs of biomagnification and the highest levels of metals were found in the macrophytes and sediments. While metal contamination in fish is probably a combination of uptake from the food and an equilibrium with the surrounding water, the levels in macrophytes appear to be determined mainly by uptake from the sediment through the roots.     

Heavy Metal Contents and Distribution in Coastal Sediments of the Gulf of Trieste (Northern Adriatic Sea, Italy)

A set of ten heavy metals (Al, As, Cd, Cr, Cu, Hg, Ni, Pb, V, and Zn) was investigated in surface sediments (0–5 cm) collected in 21 sites of the Gulf of Trieste, Northern Adriatic Sea (Italy). The aim of this work was to obtain a preliminary assessment about the levels and spatial distribution of these selected elements. Ancillary parameters such as grain size, total organic carbon, and total nitrogen were also determined. The enrichment factor was calculated to discriminate if a natural condition or a status of anthropogenic contamination occurs. In addition, a set of sediment quality guidelines, mean effect low range and effect medium range quotients, was also applied in order to predict the probability of adverse biological effects on the benthic community.     

Distribution,fractional composition and release of sediment-bound heavy metals in tropical reservoirs

The concentrations of heavy metals in bottom sediments from urban receiving waters, Kranji Reservoir and MacRitchie Reservoir in Singapore, were investigated. Distribution of the heavy metals in the bottom sediment, interstitial water and overlying water was analysed. The concentration of heavy metals in the interstitial water was found to be significantly high and exceed the water quality criteria by three to eleven times. The partitioning coefficient shows that the solubility of the metals are in the order: Mn > Zn > Cu > Pb > Fe > Al. Fractional composition of heavy metals in the sediments was determined using sequential extraction process. The results show that Cu was largely complexed by organics, 74% of Zn was in easily remobilised fractions, and 36% of Pb was in the easily reducible fraction and 47% in carbonate and ion-exchangeable fractions. Release of sediment-bound metals was studied. The results indicate that, besides pH and redox, the sediment buffering capacity is an important parameter affecting the remobilization of heavy metals from sediment.     

Review of Ecological Engineering Solutions for Rural Non-Point Source Water Pollution Control in Hubei Province,China

Anthropogenic contamination by heavy metals in fluvial systems is mostly bound to fine-grained clay minerals and organic substances, which accumulate by vertical accretion in sediment traps along river courses (oxbow lakes, dams and floodplains). These environmental settings are considered as good archives of historical changes in contamination. Much less attention, however, is paid to deposits of river channels, which act as sourcing transport paths for these archives and/or build archives of their own. In order to provide a better insight into the spatio-temporal distribution of pollutants in channel deposits, we investigated contamination levels of Cu, Pb and Zn in a series of sediment cores along the River Morava, a left-hand tributary of the Danube River, Czech Republic. In particular, the relationships between metal concentrations, sediment lithology (facies), grain size, magnetic susceptibility and mineralogy and chemistry of fly-ash particles were investigated. Element chemistry and lithology of channel deposits were compared with those of the nearby floodplain deposits in the same catchment. Four river-channel facies were defined, ranging from sandy gravels to clayey silts, and confronted with the floodplain sediments. Al/Si ratios were found to be useful proxies of grain size, and Al was utilized as an excellent normalizing element for heavy metals, which filters out much of the grain size effects on contamination. The floodplain deposits are significantly less contaminated than their river-channel counterparts. Heavy-metal contamination of river bed sediments (expressed as enrichment factors, EFs) is not simply bound to fine-grained particles, and much of the contamination was found in coarse-grained, sandy facies. Elevated EFs of Zn, Cu and Pb in several sediment layers, which show high magnetic susceptibility (MS), high values of MS normalized to Fe and a high proportion of magnetic fly-ash spherules and their chemistry suggest that significant part of the heavy-metal contamination can be carried by magnetic fly-ash spherules. A part of this contamination is bound to coarse-grained fluvial facies, indicating that the magnetic spherules can be transported as bed load sediments. Magnetic pollution and heavy-metal pollution can therefore coincide in river bed deposits. It is suggested that most of this contamination can be related to local point sources of pollutants (fly-ash deposit spills).     

Regional Pattern of Heavy Metal Content in Lake Sediments in Northeastern Poland

We investigated sediments from 23 lakes situated in northeastern Poland and analyzed them for major constituents and selected heavy metals. Short sediment cores were collected from the deepest parts of the lakes, and subsequently, a surface layer (0-2?cm) and reference layer (50-52?cm) were sampled from each. In the collected samples, the content of the major constituents (organic matter, carbonates, and minerogenic material) and chosen heavy metals (Cd, Cu, Ni, Pb, and Zn) was analyzed. In the reference layer, representing natural metal content, we identified quite a substantial diversity among lakes, making it difficult to pinpoint one geochemical background value for the whole region. A multivariate analysis of the interrelationships among elements and a comparison of the median values revealed no statistically significant differences between surface and reference levels. The ratio of the mean content in the surface and reference sediments ranged from 0.9 to 1.6, indicating the lack of or only slight anthropogenic pollution in surface sediments. From a spatial perspective, higher metal contents were observed in the eastern part of the study area, but this trend manifested in both surface and reference sediments. Thus, the inference is that the recently accumulated sediments are characterized by a content that is representative of the natural geochemical background for the selected metals.     

Mobilization Potential of Heavy Metals: A Comparison Between River and Lake Sediments

Toxic metals introduced into aquatic environments by human activities accumulation in sediments. A common notion is that the association of metals with acid volatile sulfides (AVS) affords a mechanism for partitioning metals from water to solid phase, thereby reducing biological availability. However, variation in environmental conditions can mobilize the sediment-bound metal and result in adverse environmental impacts. The AVS levels and the effect of AVS on the fate of Cu, Cd, Zn, Ni in sediments in the the Changjiang River, a suboxic river with sandy bottom sediment and the Donghu Lake, a anoxic lake with muddy sediment in China, were compared through aeration, static adsorption and release experiments in laboratory. Sips isotherm equation, kinetic equation and grade ion exchange theory were used to describe the heavy metal adsorb and release process. The results showed that AVS level in the lake sediment are higher than that of the river. Heavy metals in the overlying water can transfer to sediments incessantly as long as the sediment remains undisturbed. The metal release process is mainly related to AVS oxidation in lake sediment while also related to Org-C and Fe–Mn oxyhydroxide oxidation in river sediment. The effect of sulfides on Zn and Ni is high, followed by Cd, and Cu is easy bound to Org-C. AVS plays a major role in controlling metals activity in lake sediment and its presence increase the adsorption capacity both of the lake and river sediments.     

Sediment-bound Arsenic and Uranium Within the Bowman�CHaley Reservoir, North Dakota

The purpose of this study was to determine the impacts of regional historical uranium mining activities within sediments of the Bowman?CHaley reservoir of southwestern North Dakota. The extent of anthropogenic-influenced watershed impacts were quantified through the determination of sediment metals concentrations and metal enrichment factors to evaluate the potential of geochemically influenced As and U remobilization within the reservoir sediments. Sediment cores were collected and analyzed for total metal concentrations at five locations within the reservoir: Spring Creek delta, Alkali Creek delta, two locations within the North Fork of the Grand River confluence, and adjacent to the reservoir outfall. Pearson-moment correlations were used to establish inter-core metal correlations, while sediment enrichment factors were determined relative to background concentrations. Enrichment factor results suggest all sampling sites are classified as minor to moderately enriched for As and U. Metal behavior for the three reservoir inlets indicated similar metal loading sources and post-depositional behavior, while metals migration within the vicinity of the reservoir outlet appear to be controlled by geochemical and/or physical processes. For the reservoir outlet, As and U normalized to Al suggest the occurrence of vertical migration of As, while surface-bound U remobilization was apparent within the water column immediately above the sediments. Elevated U was found within the Spring Creek inlet, and appear attributed to historical uranium processing operations located in Griffin, North Dakota. While the reservoir As and U sediment concentrations may be considered low, their presence appears directly attributed to historical uranium mining activities within the Bowman?CHaley reservoir watershed.     

The identification of point sources of heavy metals in an industrially impacted waterway by periphyton and surface sediment monitoring

Periphyton and sediment samples were collected from 12 stations along Bayou d'Inde, a very polluted waterway, in Southwestern Louisiana. The samples were analyzed for Zn, Cu, Pb, Ni, Fe, Cr, Al, Cd, and Ag. When metal concentrations in periphyton or sediment are plotted vs sampling station, the metal distributions clearly indicate a major point source of metals at one station which is located at the mouth of an industrial ditch. Metal levels in periphyton generally parallel those found in surface sediments at the same location, but metal levels in periphyton are generally higher than in sediment from the same location, indicating an enrichment over sediment values. For sediments two types of extraction were investigated using leaching with concentrated HNO₃ in a high-pressure decomposition vessel and shaking with 1 N HCl for 2 hr. Both methods correlate well for all metals except Ni, but HNO₃ extracted more total metal. Correlations between periphyton and sediment were best for Pb, Fe, and Ag. Poorest correlations were seen for Mn, Ni, and Cd. When periphyton and sediment metal concentrations were normalized to Fe, Mn, and Al, correlation factors for some metals improved while others deteriorated.     

Hydrocarbons in Seawater and Water Extract of Jarzouna-Bizerte Coastal of Tunisia (Mediterranean Sea): Petroleum Origin Investigation Around Refinery Rejection Place

In this study, the occurrence of toxic heavy metals (As, Cd, Cr, Cu, Pb, and Zn) and relative bioaccumulation in biota samples were investigated in a freshwater ecosystem, the Basento river, one of the main aquatic systems in the south of Italy, which over the last years has been transformed into a sink of urban and industrial wastes. Therefore, the levels of arsenic, cadmium, chromium, copper, lead, and zinc were determined in water, sediments, and tissues of some macroinvertebrate—which are natural assessment endpoints for the evaluation of ecological risk in aquatic systems. Accumulation factors, as a ratio between the concentration of a given contaminant in biota and the one in an abiotic medium, were considered in order to estimate heavy metal contamination loads in biota. Statistical analysis was performed for a comparative evaluation of bioaccumulation among various macroinvertebrates, according to different feeding guilds. The Tukey honestly significantly different test showed significant differences in the bioaccumulation of As, Cd, and Cr among the considered biological receptors (collector–gatherer, predator, and filterer), suggesting that the biological uptake from immediate contact with the sediment or solid substratum (collector–gatherer), instead of the bioconcentration from water (filterer) or biomagnification along the biotic food webs (predators), is the more effective biological sequestering pathway for these metals. Biota–sediment accumulation factors, commonly used for the evaluation of sediment’s role in aquatic systems contamination, were determined for the considered metals. A linear correlation between the concentrations of As, Cd, Cr, and Zn in macroinvertebrates and those in the sediments suggested that the metal uptake data in macroinvertebrates can provide useful information for the estimation of heavy metal exposure risk or bioavailability when making assessments of sediment toxicity in freshwater ecosystems.