Unpolluted Sediments Research Articles

Genomic alterations recorded in two species of Chironomidae (Diptera) in the Upper Jurassic limestone area of the Ojców National Park in Poland attributable to natural and anthropogenic factors

The OjcĂłw National Park is situated in southern Poland in an area of Jurassic limestone, which determines the hydrochemistry of the water in the River PrÄ dnik. The geochemical index of the sediment in the River PrÄ dnik indicated it is moderately polluted with Pb and Zn, and heavily polluted with Cd compared to unpolluted sediment. The effect of natural and anthropogenic sources on the sediment in the River PrÄ dnik and in appearing of structural and functional alterations in the salivary gland chromosomes of two species of Chironomidae, Micropsectra pallidula and Polypedilum convictum, was investigated. Two types of chromosomal rearrangements (inherited and somatic) were identified in the species studied. Inherited heterozygous inversions occurred at a higher frequency (between 5.55%-57.81%) and may have local adaptive value. In M. pallidula a karyotype divergence consisting of fixed chromosome inversions on arms B and E was recorded. As somatic chromosome rearrangements can be caused by stress agents, we suggest that the somatic aberrations in both of the species studied indicate the existence of pollution, i.e. induced stress. On the basis of these somatic rearrangements the somatic index of both species was defined: M. pallidula - 0.346, P. convictum - 0.555. In addition to these rearrangements functional alterations in key structures, Balbiani rings (BRs) and the nucleolar organizer region (NOR) located on chromosome EF, which significantly decreased their transcriptional activity, were recorded in M. pallidula. Changes in the appearance of the telomere region on chromosome G in P. convictum was considered to be a response to the environmental conditions in the River PrÄ dnik. It was shown that polytene chromosomes are very sensitive to environmental changes and can be used to detect pollutants in aquatic ecosystems.

Comparison of Sulphate-reducing Bacterial Communities in Japanese Fish Farm Sediments with Different Levels of Organic Enrichment

Fish farm sediments receive a large amount of organic matter from uneaten food and fecal material. This nutrient enrichment, or organic pollution, causes the accumulation of sulphide in the sediment from the action of sulphate-reducing bacteria (SRB). We investigated the effect of organic enrichment around coastal fish farms comparing the SRB community structure in these sediments. Sediment samples with different levels of organic pollution classified based upon the contents of acid-volatile sulphide and chemical oxygen demand were collected at three stations on the coast of western Japan. The SRB community composition was assessed using PCR amplification, cloning, sequencing and phylogenetic analysis of the dissimilatory sulphite reductase β-subunit gene (dsrB) fragments using directly extracted sediment DNA. Sequencing of the cloned PCR products of dsrB showed the existence of different SRB groups in the sediments. The majority of dsrB sequences were associated with the families Desulfobacteraceae and Desulfobulbaceae. Clones related to the phylum Firmicutes were also detected from all sediment samples. Statistical comparison of sequences revealed that community compositions of SRB from polluted sediments significantly differed from those of moderately polluted sediments and unpolluted sediments (LIBSHUFF, p<0.05), showing a different distribution of SRB in the fish farm sediments. There is evidence showing that the organic enrichment of sediments influences the composition of SRB communities in sediments at marine fish farms.

Comprehensive Analysis of Heavy Metals in Sediments Contaminated by Different Pollutants

Instrumental analyses were combined with the community bureau of reference (BCR) sequential extraction procedure (SEP) to study heavy metal pollution in sediments exposed to different pollutant compositions (primarily inorganic, primarily organic, and an upstream control sample). Heavy metals accumulated primarily in the nonresidual fractions of sediments as revealed by sequential extraction. The discharge of waste water with different pollutant compositions differentially affected the distribution of heavy metal species in extracts from sediments. Sediment polluted by organic waste water had a higher proportion of heavy metals in the oxidizable fraction. A higher residual fraction was detected in the sample that was polluted by high fluorine waste water. For all sediment samples, most Pb was found in the reducible fraction. The oxidizable fraction contained most of the chemically extractable Cu and Cr (31.6–81.5%); whereas the highest percentage of Zn was found in the residual fraction for all samples (46.9, 37.8, and 65.4%, respectively). The mobility order of the heavy metals studied in polluted sediments was Cr>Cu>Pb>Zn, much different from the order Cu>Pb>Cr>Zn found in the control unpolluted sediment sample.

Caractérisation physico-mécanique d'un sédiment brut et traité à la chaux

ABSTRACT In a context of sustainable development, the management of sediment depends on their potential to induce pollution. The old management techniques used as immersion in the sea by overfflow, dumping or storage is restricted due to regulation which is increasingly rigid in terms of environmental protection. The new trend of all actors in the field of sediment management is moving ineluctably towards an alternative solution as the valorisation of the sediments as. Any valorisation requires a stage of characterisation in order to enhance the knowledge about the material: its various components, its potential to induce pollution and its mechanical behaviour. Our work consists, on the one hand, in carrying out a comparative study of mechanical and physical behaviours, between polluted and unpolluted sediment and on the other hand, to underline the evolution of the behaviour of polluted sediment following a lime treatment. The sediment in question is considered as a raw material as it has not been subject to any process of pre-treatment.

Sediments and the “System”: from site-specific to regional-scale research

Sediments are part of the erosion–sedimentation cycle; material from the terrestrial environment is turned into rock, boulders and sand-, siltand clay-sized particles through weathering, which are subsequently transported by wind and water erosion through rivers, and ultimately end up in the ocean. During transport, temporary deposition takes place in the river beds, flood plains, wetlands, deltas and estuaries (Fig. 1). In these depositional areas, sediment is an integral part of the ecosystem. Geology deals with research in both ancient and recent deposits of sediments. More than 14,000 books listed by Amazon under the search term “sediments” reflect the current education and research effort on this topic, which started more than 200 years ago (Hutton 1788). The more recent aspects of sediments and sedimentology are covered by our journal; the impact of humans on the quality and quantity of sediments in aquatic systems. Here, the survey of Amazon, using “sediment pollution”, shows about 1,200 books which are still for sale. On the other hand, searching in Google Scholar really shows how active our field is: for “sediment”, there are 1,460,000 hits and for “sediment pollution”, the number is 583,000. These simple crude statistics suggest that one third of all sediment research deals with pollution aspects. Looking back, research on sediment pollution reflects the typical sequence of academic research through research for legislation to implementation (Fig. 2). In the first part of the twentieth century, sediment pollution research was in the realms of classic geochemistry (Goldschmidt 1954). Important applied areas included research for ore prospecting and micronutrients in soil science. In fact, in The Netherlands, elevated levels of heavy metals in wetlands from the Rhine–Meuse delta were detected during soil surveys in order to determine their potential for agricultural use after embankment. Human fatalities in Japan, linked to sediments and soils (Hagino and Yoshioka 1961; Fujiki 1972), caused worldwide concern. These and other incidents really put contaminated sediments on the political agenda as a societal issue. Hence, since the 1970s sediment research became policy driven with ample funding to determine its extent and potential impact (i.e. “Coming to Grips” in Fig. 2). Subsequently, several techniques were developed to determine and predict such impacts. These included geochemical modelling of aquatic systems (e.g. Garrels and Christ 1965; Stumm and Morgan 1971) and the biogeochemical processes in the deposited sediments (e.g. Berner 1971) and the introduction of bio-assays (e.g. Sunda and Guillard 1976). In addition, comparisons were made with contaminant levels to those found in unpolluted sediments, and the mode of occurrence of contaminants in sediments was studied to infer their reactivity (e.g. Forstner and Salomons 1980). For both of us, it has been a struggle on how to write a kind of official “Farewell address” to our colleagues. After all, we do it only once in our lifetime. The result is twofold; we will have one editorial with a broad and short (admittedly very biased) history and outlook of our experience, and a second, more scientific editorial, which covers the first 10 years of our Journal of Soils and Sediments.

Single and combined effects of hypoxia and contaminated sediments on the amphipod Monoporeia affinis in laboratory toxicity bioassays based on multiple biomarkers

In estuaries, hypoxic conditions and pollution are among the major factors responsible for the declines in habitat quality, yet little is known about their combined effects on estuarine organisms. In this study, to investigate single and combined effects of hypoxia and contaminated sediment, the Baltic amphipod Monoporeia affinis was exposed for 5–9 days to four different combinations of oxygen conditions (moderate hypoxia vs. normoxia) and contamination (polluted vs. unpolluted sediments) at environmentally realistic levels. To detect oxidative stress, a suite of biomarkers was used – antioxidant enzymes [superoxide dismutases (SOD), catalase (CAT), and glutathione S-transferases (GST)], acetylcholinesterase (AChE), lipid peroxidation status (TBARS concentration), protein carbonyl content (PCC), and DNA strand breakage (DNA-SB). To assay effects at the organism level, we used RNA:DNA ratio as a proxy for growth and metabolic rate and mortality. There were significant increases in CAT and SOD activities and TBARS levels in response to both moderate hypoxia and contaminated sediment, while GST increased and AChE decreased in response to the contamination only. Significant positive correlations were observed among the antioxidant enzymes and between the enzyme activities and TBARS concentration, suggesting a complex response to the oxidative stress. No significant changes in PCC were recorded in any of the treatments. Furthermore, the negative effect of hypoxia on DNA integrity was significant; with frequency of DNA-SB increasing in animals exposed to hypoxia in contaminated sediment. Despite clear effect at the cellular and biochemical levels, no responses at the organism level were observed. Multivariate analyses of the dataset have allowed us to link exposure factors to individual biomarker responses. Of the potential biomarkers assessed in this study, CAT activity was found to be associated with hypoxia, while SOD, GST and AChE activities appear to predict best the effects of exposure to sediments containing several contaminants (e.g. heavy metals, PCBs and PAHs), and TBARS concentration is particularly indicative of combined effects of hypoxia and contamination. In addition to providing new knowledge on the combined effects of multiple stressors on estuarine organisms, the findings of the present study are also important to understand data from biomonitoring studies in the Baltic Sea and in other regions where multiple stress factors co-occur.

Comparison of bacterial communities in fish farm sediments along an organic enrichment gradient

Aquaculture is of major industrial importance world wide and this has led to concerns over the impact of fish farming on previously pristine marine environments. Fish farm sediments receive a large amount of organic matter due to uneaten food and fecal materials. This organic enrichment of sediment influences the biogeochemical process and benthic microbial communities. This study was performed to investigate the effect of pollution from marine fish farms on the bacterial community structure in the underlying sediments. Sediment samples were collected at four stations along an organic enrichment gradient on the coast of Wakasa Bay in southern Fukui Prefecture, Japan between April 2004 and December 2006. Sagami Bay sediments were also used as a non-fish farming reference site. The bacterial community composition was assessed using PCR amplification, cloning, sequencing, and phylogenetic analysis of 16S rDNA using directly extracted sediment DNA. Most of the clones sequenced fell into six major lineages of the domain Bacteria: γ-, δ-, ε-Proteobacteria, Acidobacteria/ Holophaga, Bacteroidetes, and Planctomycetes. Although there were no significant differences in the bacterial community structures among the sediment samples except for Sagami Bay, a minor change in the composition of 16S rDNA operational taxonomy units (OTUs) between sites was recognized. 16S rDNA sequences related to the γ-Proteobacteria were recovered with relatively higher frequencies from unpolluted sediments than from polluted sediments. In contrast, the most abundant clone sequences from polluted sediment samples were grouped with δ-Proteobacteria. Our data suggests organic enrichment of sediment may influence the composition of bacterial communities; and the δ-Proteobacteria were found and selected for within polluted fish farm sediments.

Local adaptation of microbial communities to heavy metal stress in polluted sediments of Lake Erie

Microbial communities must balance the assimilation of biologically necessary metals with resistance to toxic metal concentrations. To investigate the impact of heavy metal contaminants on microbial communities, we performed two experiments measuring extracellular enzyme activities (EEA) in polluted and unpolluted sediments of Lake Erie. In the first experiment, inoculations with moderate concentrations of copper and zinc appreciably diminished EEA from uncontaminated sites, whereas EEA from contaminated sediments increased or were only negligibly affected. In the second experiment, we compared the effects of three separate metals (i.e. copper, arsenic, and cadmium) on microbial community metabolism in polluted and unpolluted locations. Although copper and arsenic elicited differential effects by inhibiting EEA only in unpolluted sediments, cadmium inhibited EEA in both polluted and unpolluted sediments. Multivariate analyses of EEA from polluted sediments revealed direct associations among hydrolytic enzymes and inverse or absent associations between hydrolases and oxidases; these associations demonstrated resilience to heavy metal stress. In contrast, addition of heavy metals to unpolluted sediments appeared to have a higher impact on the multivariate pattern of EEA associations as revealed by an increase in the number of associations, more inverse relationships, and potential enzymatic trade-offs. The results of this study suggest community-level adaptations through the development of resistance mechanisms to the types and local levels of heavy metals in the environment.

Geochemical Distribution of Trace Metals and Assessment of Anthropogenic Pollution in Sediments of Old Nakagawa River, Tokyo, Japan

The geochemical distributions of cadmium (Cd), copper (Cu), chromium (Cr), lead (Pb) and zinc (Zn) were examined in sediments collected from Old Nakagawa River (NR), Tokyo, Japan. A widely used 5-step sequential extraction procedure was employed for the fractionation of the metals and the concentrations were measured in the liquid extracts by inductively coupled plasma mass spectrometry (ICP-MS). The association of Cd (76-98%) and Zn (48-67%) were found highest with AEC (adsorbed/exchangeable/carbonate) phase, Cu (45-60%) and Pb (44-73%) with amorphous Fe oxyhydroxide phase and the maximum fractionation of Cr was in both crystalline Fe oxide (12-60%) and amorphous Fe oxyhydroxide phase (15-60%). For retention by amorphous Fe oxyhydroxide minerals, the observed stoichiometric gradient was: 1.52 for Cu, 1.23 for Pb, 2.25 for Cr and 3.09 for Zn. Corresponding values for association with crystalline oxides and sulphides and organics were an order of magnitude greater than those for amorphous oxyhydroxide, indicating a greater affinity of trace metals for these phases. The total concentration ranges of Cd, Cr, Cu, Pb and Zn in NR sediments were 2.86-16.95, 551.7-3953.1, 340.6-1565.3, 136.9-385.9 and 931.4-3650.1 µg g-1, respectively. The observed order of potential trace metal mobility in the aquatic system was: Cd>Zn>Pb>Cu>Cr. Organic carbon contents in sediment samples were comparatively high (mean 5.48%) and the X-ray diffraction (XRD) study detected the presence of several clay minerals, those are likely to be major host of trace metals in sediments. The sediments of NR was considered to be polluted on the basis of unpolluted sediments and geochemical background values with respect to Cd, Cr, Cu, Pb and Zn. According to the enrichment factors (EFc), most of the sites have several times higher values of trace metals than the standard. The study revealed that the pollution in sediments of NR could be linked to anthropogenic activities such as industrialization, urbanization, deposition of industrial wastes and others.

Deriving effects on Chironomus population carrying capacity from standard toxicity tests

Translating effects from individual to population level is a crucial issue in ecological risk assessment of bed sediments. We first propose a modeling package to tackle this question for the species Chironomus riparius with biology- and ecology-based models to deduce effects on chironomid production per generation or per year. However, this approach requires the performance of many toxicity tests. Currently, the information available to perform this scaling is limited to a few data from standardized tests, mainly growth and survival after a certain period of time and sometimes emergence after 28 d. We propose here to simplify our model to make it able to deal with only data from standardized tests. The daily death rate is assumed to be constant throughout each instar, the effects on growth to be independent of time, and the effects on reproduction to be negligible. The reliability of this approach is first tested by comparing the population effects on organisms exposed to copper-spiked sediments calculated with the simple model and the more exhaustive one from which it was derived. The simple model just slightly underestimated the effects at the population level. Second, data from tests performed either with unpolluted sediment or with field sediment with different degrees of contamination are used to propose an effect threshold for populations. It appears that control sediments lead to less than 20% effects at population level, which may help define a natural variability range. For polluted sediments, we could find effects up to 42%. Implications of these findings are discussed in a sediment risk assessment perspective.

Effects of long‐chain hydrocarbon‐polluted sediment on freshwater macroinvertebrates

High-molecular weight (> C16) hydrocarbons (HMWHs) are common pollutants in sediments of freshwater systems, particularly urban water bodies. No sediment quality guidelines exist for total hydrocarbons; more emphasis is placed on polyaromatic hydrocarbons, the most toxic component of hydrocarbons. A field-based microcosm experiment was conducted to determine whether unpolluted sediments spiked with synthetic motor oil impair freshwater macroinvertebrate assemblages. Total petroleum hydrocarbon (TPH) concentrations of 860 mg/kg dry weight significantly increased the abundance of Polypedilum vespertinus and Cricotopus albitarsis and decreased the abundance of Paratanytarsus grimmii adults (all Chironomidae), whereas TPH concentrations ranging from 1,858 to 14,266 mg/kg produced a significant reduction in the total numbers of taxa and abundance, with significant declines in the abundance of nine chironomid taxa. About 28% of water bodies surveyed in urban Melbourne, Australia, had TPH concentrations in sediments likely to cause ecological impairment, and about 14% of the water bodies surveyed are likely to have reduced species richness and abundance. Therefore, HMWHs can be a significant pollutant in urban water bodies. Freshwater sediment quality guidelines should be developed for this ubiquitous urban pollutant.

Temporal and spatial variations in the geochemistry of major and minor particulate and selected dissolved elements of Thermaikos Gulf, Northwestern Aegean Sea

The objectives of this study were to examine both spatial and temporal changes of particulate major elements and minor metals, as well as dissolved Mn and Cd, in the waters of Thermaikos Gulf. Collections of water and suspended particulate matter (SPM), as depth profiles (5–8 depths), were undertaken at 10 principal stations, essentially on a N–S traverse of the western side of the Gulf. One of the principal aims of the study was to observe if there was any change in the patterning of the elements between the three occupations of the stations: (a) in September 2001, immediately before the commencement of trawling; (b) in October 2001, whilst fishing was active; and (c) in winter/early spring conditions (February 2002), when fishing was still active, but after a change of river/atmospheric conditions. Bottom (∼20 m) waters were dominated by sediment resuspension; this was identified by concentration changes in the aluminosilicate elements (e.g. Al, Ti, K, Fe) of the SPM. A two- to three-fold increase occurred between September and October, caused probably by trawling; this was sustained at the offshore stations, in February. During February, the western inshore stations showed little sediment resuspension, caused by extreme winter cooling and the sinking of water. Consequently, a N–S density discontinuity existed at all water depths, which prevented the thermohaline cyclonic circulation from penetrating into the western seaboard of the Gulf. The distribution of dissolved and particulate Mn in the lower waters was due to redox cycling of the element at the benthic boundary; this was more intense in the north, where the organic supply was higher. Biogenic element concentrations and Ca/Al, Si/Al ratios showed no evidence that trawling activity promoted higher biological production. Strong correlations of Co, Cr, Ni and V, with Al and K, showed that these elements were associated strongly with detrital aluminosilicates. However, the variable association of Cd, Pb and Zn, with K (and Al), especially in the upper waters, implied an anthropogenic source derived from the rivers and the city of Thessaloniki. Examination of the Kd's of Cd showed a two-order of magnitude decrease with depth, caused by resuspension and possible advection of relatively unpolluted sediments, into the western Gulf.

A new sediment contact assay to assess particle-bound pollutants using zebrafish (danio rerio) embryos

Goal, Scope and Background. Based on a bioassay battery covering only primary producers and consumers as well as degraders, the potential ecological hazard of sediments to vertebrates cannot be estimated comprehensively. Therefore, there is an urgent need to develop and standardize integrated vertebrate-based test systems for sediment investigation strategies. Whereas vertebratebased in vitro systems have frequently been used for the investigation of aqueous samples, there is a significant lack of whole sediment assays. Thus, the purpose of the present study was: (1) to develop a rapid and reliable, but comprehensive method to investigate native sediments and particulate matters without preceding extraction procedures; (2) to compare the hazard potential of solid phase sediments to the effects of corresponding pore waters and organic extracts in order to characterize the bioavailability of the particle-bound pollutants; and (3) to relatively evaluate the embryotoxic effects of sediments from the catchment areas of the rivers Rhine, Neckar and Danube.Methods (or Main Features).To investigate the toxicity of sediment samples on vertebrates, the standard embryo toxicity test with the zebrafish (Danio rerio; Hamilton-Buchanan 1922) according to DIN 38415-6 was modified with respect to exposure scheme and toxicological endpoints. Sediments from the catchment area of the Neckar River were assessed using pore waters, acetonic extracts and native sediments in order to get inside into the potential bioavailability of particle-bound pollutants. A comprehensive test protocol for the investigation of native sediments in the embryo toxicity test with the zebrafish is presented.Results and Discussion.The fish embryo assay with Danio rerio can be carried out with both aqueous and organic sediment extracts as well as native (whole, solid phase) sediment samples. Elongation of exposure time from 48 to up to 196 h significantly increased the mortality. Using the fish egg assay with native sediments, a broad range of embryotoxic effects could be elucidated, including clear-cut dose-response curves for the embryotoxic effects of contaminated sediments; in contrast, absence of embryotoxic effects could be demonstrated even for the highest test concentrations of unpolluted sediments. With native sediments, embryotoxicity was clearly higher than with corresponding pore waters, thus corroborating the view that — at least for fish eggs — the bioavailability of particle-bound lipophilic substances in native sediments is higher than generally assumed. The relative ranking of sediment toxicity was identical using both native sediments and sediment extracts, EC20 values of the latter, however, being eight time lower higher than with the native sediments. A comparison of the embryo toxic effects of samples from the Neckar area with locations along the Rhine and Danube rivers elucidated a broad range of results, thus indicating different levels of contamination.Conclusions.A modified protocol of the zebrafish embryo test allows the assessment of sediment toxicity in both aqueous extracts and native sediments. The isolated investigation of pore waters may result in a clear-cut underestimation of the bioavailability of lipophilic particle-bound substances (as determined by native sediments).Recommendations and Perspectives.The zebrafish embryo test with native (whole, solid phase) sediments appears very promising for the evaluation of the bioavailable fraction of lipophilic particle-bound substances and can therefore be recommended for the evaluation of vertebrate toxicity in tiered sediment test strategies and dredging directives such as the HABAB-WSV. Whereas acetone extracts may be tested as a rough estimation of embryotoxicity, native sediment samples will provide a more comprehensive and realistic insight into the bioavailable hazard potential

Three decades of investigations on heavy metals in coastal sediments, North Arctic Alaska: A synthesis

Concentrations of V, Cr, Cu, Ni, Zn, As, Cd, Pb, Ba, Fe, Mn, total and methyl Hg were measured in muddy sediments from urbanized Elson Lagoon adjacent to Barrow Village, industrialized Colville Delta-Prudhoe Bay, and relatively pristine Beaufort Lagoon adjacent to the Arctic National Wildlife Refuge, Beaufort Sea, north Arctic Alaska. Comparison of the mean concentrations of the metals at approximately 10-year intervals (1977, 1986, 1997), within the Colville Delta-Prudhoe Bay shows significantly increased concentrations of V in 1986 and 1997 from 1977 and an increase in Ba from 1986 to 1997. No significant changes were noted in the concentrations of other elements. The sources of V and Ba contaminants are unknown. The levels of all metals are below or similar to those in unpolluted marine sediments. The geochemical partitioning of selected metals was deduced from metal analyses in the lithogenous and non-lithogenous sediment fractions. Of the total contents -50% of Mn, 25-35% Co, 15-20% Zn, Cu and Ni, 10% of V and Fe and <3% of Cr are bound in the non-lithogenous phase, presumably in organic matter, clays and Fe-Mn oxide/hydroxides. In contrast, almost all of Cr, Cd and Ba are lattice-held, and <1% of Hg is methylated.

Variations in trace elements in bottom sediments of major rivers in Lake Victoria's basin, Kenya

AbstractRiver sediments collected between March 1994 and January 1995 were analysed for iron (Fe), manganese (Mn), zinc (Zn), lead (Pb), copper (Cu), chromium (Cr), aluminium (Al) and cadmium (Cd) in the less than 63 μm grain‐size fraction. The river sediments were characterized by a sandy texture, with a relatively low organic matter (as percentage loss on ignition), ranging 3.5–9.6%. The metal mean range values in μg/g dry weight for the river sediments were: Mn (836–2.10 × 104), Fe (1.09 × 104–9.22 × 104), Al (2.86 × 103–7.77 × 103), Zn (34–130), Cu (11–78), Cr (not detected ND–125); Pb (ND–100) and Cd (ND). Temporal variations were significant for Zn, Cr and Pb. There were no significant longitudinal differences in all the elements in rivers Nyando, Nzoia, Yala and Sondu‐Miriu, apart from sediment Fe contents. Relatively high sediment Fe, Mn, Zn, Cr and Al were observed in river Kasat. River Kasat was considered polluted with respect to Mn, Zn and Cr, which were comparatively higher than unpolluted sediments and geochemical background values. This supports similar results on surface water trace element levels. Most of the rivers drain an area of relatively similar lithological characteristics. Therefore, apart from the direct waste input into Kasat river from municipal and industrial sources, lack of specific point sources indicate lithological metal origins with localized variations. A final comparative evaluation of the river sediments’ trace metal pollution was made from the study results. The data is vital for pollution management of the lake as information about metal loadings into the lake ecosystem is lacking.

Polycyclic aromatic hydrocarbons (PAHs) and organochlorines (OCs) in bottom sediments of the Guba Pechenga, Barents Sea, Russia

Surface sediment samples from the Guba Pechenga and adjacent areas: Varangerfjord, Guba Malaya Volokovaya and Guba Bol'shaya Volokovaya (south-western Barents Sea) collected in March–April 1997 were analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), chlorinated pesticides: p,p′-DDT, p,p′-DDE, p,p′-DDD, α- and γ-HCH, and hexachlorobenzene (HCB). Mean ∑PAH (sum of the two- to six-ring PAHs) concentration in sediments from the Guba Pechenga (1481 ng/g dry wt.) was significantly higher than in sediments from adjacent areas (252 ng/g dry wt.), where PAH contamination levels were similar to reported for unpolluted sediments of the northern Norway fjords and open parts of the Barents Sea. Differences between HCB levels as well as ∑HCH (sum of α- and γ-HCH) levels found in Guba Pechenga sediments and adjacent area sediments were not significant. Concentrations of these contaminants varied in ranges 0.28–1.76 and 0.05–0.68 ng/g dry wt., respectively, and were consistent with literature data on PAH levels in sediments from the northern Norway harbours, Kola Bay (Russia) and south-eastern part of the Barents Sea. Average total DDT concentration in Guba Pechenga sediments (10.5 ng/g dry wt.) was one and 2–3 orders higher than those found in sediments from the Pechora Sea and from the seas of eastern Arctic, respectively, however, it was comparable with DDT levels reported for harbours of northern Norway and Kola Bay. Significant difference between total DDT levels in Guba Pechenga and in the adjacent areas (mean 1.8 ng/g) was found. Among compounds of DDT family, p,p′-DDT isomer prevailed in all sediment samples indicating a possible local ‘fresh’ DDT source. Mean ∑PCB (sum of PCB-28, 31, 52, 101, 118, 105, 153, 138, 156, 180, 209) concentration in the Guba Pechenga sediments (12.8 ng/g dry wt.) was significantly higher than in sediments of adjacent areas (2.1 ng/g dry wt.), but it was lower in comparison with ∑PCB levels reported for the northern Norway harbours and Kola Bay sediments. The highest levels of contaminants were found in sediments collected close to the Liinakhamari harbour. The origin of both PAHs and OCs in the Guba Pechenga sediments is a combination of local sources and long-range transport from lower latitudes.

Heterotrophic bacterial floras in industrial area and unpolluted marine environments around Qingdao

From Oct. 1999 to Oct. 2000, the heterotrophic bacterial floras in the industrial marine environment around the Qingdao Power Plant (QPP) and in the unpolluted marine environments were investigated. The results showed that the numbers of the heterotrophic bacteria around QPP were much higher than those in unpolluted environments, and the average numbers in QPP Seawater, QPP Sediment, Unpolluted Seawater and Unpolluted Sediment were 5.4×104cfu(mL)−1, 5.0×105cfug−1, 3.0×102cfu(mL)−1 and 1.3×105cfug−1 respectively. Totally, 118 strains were isolated from QPP and 99 of them were Gram-negative. One hundred and twenty one strains were isolated from the unpolluted environments and 104 of them were Gram-negative. All the Gram-negative bacteria belonged to 13 genera. The distribution of the bacteria was varied in different marine environments. The results showed that the unpolluted marine environments contained much more Vibrio than seawater and sediment around QPP.

Pollution of a water course impacted by acid mine drainage in the Imgok creek of the Gangreung coal field, Korea

The purposes of this study are to (i) determine the geochemical characteristics of Imgok creek impacted by acid mine drainage (AMD) generated from abandoned coal mines, (ii) to assess the pollution of heavy metals in the stream sediments and soils, and (iii) to identify the chemical form of Fe precipitates collected in the study area where there are 4 abandoned coal mines, which belong to the Grangreung coal field at the eastern part of Korea. AMD generated from mine adits and coal refuse piles shows low pH, and high concentrations of Fe, Al and SO4, especially in the Youngdong coal mine. In Imgok creek, pH values increased, and total dissolved solids (TDS) values decreased with distance. The concentrations of toxic heavy metals and major cations except Fe decreased by dilution, but the concentration of Fe decreased rapidly due to the formation of precipitates. The quality of groundwater samples did not exceed the Korean drinking-water standard. In the stream sediments, the concentrations of Fe are relatively high in the Youngdong tributary and Imgok creek, but the concentrations of heavy metals are similar to those of unpolluted sediments. Pollution indices of agricultural soils range from 0.28 to 0.47. Yellowish red Fe precipitates collected in the study area turned out to be amorphous or poorly crystallized minerals (determined by X-ray diffraction patterns and Feox/Fetot ratios) and to contain chemically bonded SO4 and OH [determined by infra-red (IR) spectral analysis]. With these, the mol ratios of Fe/S ranging from 4.6 to 6.1 determined by electron probe micro-analysis (EPMA) in precipitates strongly support the existence of schwertmannite.

Entrapment of pollutants in Mediterranean sediments and biogeochemical indicators of their impact

The transit and fate of certain pollutants (Cd, Pb, Zn and P) transported to the western Mediterranean sea-floor and a method to assess their impact are described. The spatial distribution of pollutant concentrations in the Rhone prodelta shows that their decline with distance from their source is due both to mixing with unpolluted sediments, release from contaminated particles during transit and release from sediments after deposition. Beyond the continental shelf, metals of anthropogenic origin, mainly incorporated in faecal pellets, sink and become entrapped in deep sea sediments. Because subsaturating concentrations of trace metals are often found in surface pore waters and storage, therefore, still occurs, co-precipitation with other metal ions existing in slightly supersaturated states has also to be considered. Although phosphate tends to precipitate as apatite after entering sea water, its `definitive' storage in sediments is hindered by certain forms of pollution. Low pH and reducing conditions in sediments enhance phosphate release to the overlying water . Eutrophication may then occur in localised areas. The effects of urban waste water contamination on biogeochemical processes in sediments are examined, in particular processes responsible for the transformation of organic nitrogen. Sediment quality appears to be better defined by the effectiveness of diagenetic processes than by pollutant concentration per se. In general, polluted sediments possess weak capacities to transform organic nitrogen relative to the quantities of organic matter that are available. Such sediment characteristics are indicated by the preferential growth of Caulerpa taxifolia over that of Posidonia oceanica.

Four thousand years of atmospheric lead pollution in northern Europe: a summary from Swedish lake sediments

This paper presents a large palaeolimnological study of the pre-industrial and industrial history of atmospheric lead pollution deposition in Sweden. Both lead concentrations and 206Pb/207Pb ratios have been analysed in 31 lakes covering most of Sweden, plus one lake in north-west Russia. Four of the lakes have varved (annually-laminated) sediments. Isotope analysis is a sensitive and effective method to distinguish pollution lead from natural catchment lead and to detect early pollution influence, because the 206Pb/207Pb ratio in unpolluted background sediments in Sweden was > 1.3, while that of lead from pollution, derived from ores and coal, was < 1.2. The sediments show a consistent picture of past temporal changes in atmospheric lead pollution. These changes include: the first traces of pollution 3,500-3,000 yrs ago; a pollution peak in Greek-Roman Times (about 0 AD); lower lead fall-out between 400 and 900 AD; a significant and permanent increase in atmospheric lead fall-out from about 1000 AD; an increase with the Industrial revolution; a major increase following World War II; the maximum peak in the 1970s; and decreasing fall-out over the last decades. The four varved sediments provide high-resolution records of atmospheric pollution. They reveal pollution peaks about 1200 and 1530 AD which match the history of metal production in Europe. According to the varve records the lead pollution level in the late 1990s had decreased beneath the level of the 1530s. The pollution level 1200 AD was about 35% of the 1980s, when lead pollution was still near its all time high. About 50% of the total accumulated atmospheric lead pollution deposition through time was deposited in the pre-industrial period. The sediments also show a consistent picture of the geographic distribution of atmospheric lead deposition over time, with higher deposition in south Sweden and declining levels to the north, which supports the hypothesis that the main sources of pre-industrial atmospheric lead pollution in Sweden were cultural areas in mainland Europe and Great Britain.