Lead in the Soils and Stream Sediments of an Urban Catchment in Tyneside,UK

This paper focuses on lead contamination in topsoils and stream sediments of public access areas in a largely urban UK catchment. It compares severity of contamination with accepted trigger thresholds, examines spatial patterns relative to urban and industrial development, and explores potential mobility of lead using ‘plant available’: total lead ratios. Total and ‘plant available’ lead concentrations, organic content and pH were determined on 298 topsoil and 54 stream sediment samples using standard laboratory procedures. At the lowest total lead trigger threshold, approximately two thirds of topsoil and one third of stream sediment samples were contaminated. For ‘plant available’ lead the proportions were somewhat lower. The spatial pattern was characterised by ‘hot spot’ contamination, with highest values occurring in central and southern parts of the catchment which have a long urban and industrial history. Potential lead mobility is greatest in rural western and northern parts of the catchment where the lead fractions are probably derived from pedological alteration and weathering of soil parent materials. Conversely, in the urban and industrial areas, much of the lead probably consists of less mobile particulate forms. The implications of these findings for assessment, monitoring and management of contaminated areas are discussed.     

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.     

Chronic toxicity of unresolved complex mixtures (UCM) of hydrocarbons in marine sediments

Background, Aim and Scope  Unresolved complex mixtures (UCM) of hydrocarbons, containing many thousands of compounds which cannot be resolved by conventional gas chromatography (GC), are common contaminants of sediments but little is known of their potential to affect sediment-dwelling organisms. Evidence exists for reduced health status in mussels, arising from aqueous exposure to aromatic UCM components acting through a narcotic mode of action. However, UCM contaminants in sediments may not be sufficiently bioavailable to elicit toxic effects. The aim of our study was therefore to measure the sublethal effects of chronic exposure to model UCM-dominated oils at environmentally realistic concentrations and compare this to effects produced by a UCM containing weathered crude oil. A further aim was to determine which, if any, fractions of the oils were responsible for any observed toxicity. Materials and Methods  Whole oils were spiked into estuarine sediment to give nominal concentrations of 500 μg g⁻¹ dry weight. Juveniles of the estuarine amphipod Corophium volutator were exposed to the contaminated sediment for 35 days and their survival, growth rate and reproductive success quantified. Using an effect-directed fractionation approach, the oils were fractionated into aliphatic and two aromatic fractions by open column chromatography and their toxicity assessed by further chronic exposures using juvenile C. volutator. Results  The growth rates of amphipods were reduced following exposure to the oils although this was only statistically significant for the weathered oil; reproductive success was reduced by all oil exposures. Sediment spiked with UCM fractions also caused reduced growth and reproduction but no particular fraction was found to be responsible for the observed toxicity. Survivorship was not affected by any oil or fraction. Discussion  The study showed that chronic exposure to sediments contaminated by UCM-dominated oils could have population level effects on amphipods. The observed effects could not be explained by hydrocarbons resolved by conventional GC and effects were similar for both UCM-dominated and weathered oils. All of the fractions appeared to contribute to the observed effects; this is in contrast to previous research which had shown that an aliphatic UCM did not cause adverse effects in mussels. Conclusions  To our knowledge, this is the first study to demonstrate population-level effects arising from exposure to sediments contaminated by realistic environmental concentrations of UCM hydrocarbons. The results are consistent with many compounds, at very low individual concentrations, contributing towards the overall observed toxicity. Recommendations  Risk assessments of contaminated sediments should take into account the contribution towards the potential for toxic effects from UCM hydrocarbons. Studies into sediment contamination should report both aliphatic and aromatic UCM concentrations to aid risk assessments. ESS-Submission Editor: Henner Hollert (hollert@uni-heidelberg.de) This paper has been developed from a presentation at SETAC Europe 16^th Annual Meeting 2006 held at the The Hague, The Netherlands.     

Cadmium contamination of sediments in the water reservoirs in Silesian Upland (southern Poland)

Purpose

Cadmium (Cd) is considered a toxic element and its concentrations are relevant to human health and the environment. Therefore, the purpose of the study was to determine the extent to which the bottom sediments of water bodies (artificial lakes and ponds) in the Silesian Upland in southern Poland are contaminated with Cd; an attempt was also made to determine the factors that condition spatial differences in the concentration of this element between individual water bodies in the region.

Materials and methods

Measurements of the Cd content in bottom sediments were carried out in 35 water bodies in southern Poland in 2011 and 2012. Depending on the surface area and morphometric characteristics, from two to nine samples representative in terms of sediment thickness were collected in each water body. Cadmium concentrations were determined for 92 0.25 g aliquots using the TD-ICP method.

Results and discussion

Cadmium content in all samples (0.7–580.0 mg kg^?1) was higher than the natural range of concentrations for this element in the Earth’s crust (0.1–0.3 mg kg^?1) and the geochemical background for Poland (0.5 mg kg^?1) and, with a few exceptions, was also higher than the preindustrial concentration (1.0 mg kg^?1) and the regional geochemical background (2.5 mg kg^?1). Adopting natural Cd concentrations in the Earth’s crust (0.1–0.3 mg kg^?1) as the baseline for the geoaccumulation index (I_geo), the sediments examined can be classified as extremely and heavily contaminated (and moderately contaminated in a small number of cases). The assessment of sediment quality based on I_geo, with the regional geochemical background (2.5 mg kg^?1) adopted as the baseline, results in non-contaminated and moderately contaminated sediments being dominant with a far smaller number of heavily and extremely contaminated ones.

Conclusions

In the case of several water bodies, Cd concentrations were at record levels that have not been found anywhere else in the world. On the basis of the I_geo, sediments of varying quality were found—from virtually uncontaminated to extremely contaminated. The I_geo index as an indicator of the quality of bottom sediments is a measure that requires careful interpretation, especially when different concentration levels regarded as natural are used for determining its value.

     

Using solid-phase microextraction to evaluate the role of different carbon matrices in the distribution of PAHs in sediment-porewater systems of the Baltic Sea

Purpose  

The speciation of polycyclic aromatic hydrocarbons (PAHs) in sediment-porewater systems affects both the chemical fate and bioavailability of these compounds. PAHs may be dissolved or sorbed to sediment particles or dissolved organic carbon (DOC). Furthermore, soot carbon has been shown to control the sorption of PAHs onto particles in natural waters. The present study investigates the distribution of individual PAHs among these three phases by examining sediments from the western Baltic Sea, focusing on a highly contaminated former dumping area and evaluating the importance of soot-carbon partitioning.     

Soil and Atmospheric Inputs to PAH Concentrations in Salt Marsh Plants

Polycyclic aromatic hydrocarbons (PAHs) were measured in two wetland plant species grown outdoors in pots of sediment contaminated with up to 730,000 μg/kg total PAHs. After approximately 3 months, the plants were harvested, cleaned, and analyzed for an expanded suite of PAHs which included both the 16 priority PAHs and 22 alkyl PAH homologs. Sediment and air samples were also collected and analyzed. PAH compounds were detected in all of the samples, with the highest concentrations in the contaminated sediment. The root sample concentrations were generally about one order of magnitude lower than that of the sediment, and were strongly correlated with the concentration in the sediment in which they were grown. The concentrations in foliage were much lower and did not correlate with sediment concentration. Concentrations of low molecular weight PAH compounds detected in the foliage were not significantly lower in plants grown in control sediments, suggesting that the sediment is not the primary source of these PAHs. Several high molecular weight PAHs were detected only in plants grown in contaminated sediment. Plants of both species grown in control sediment were larger than plants grown in contaminated sediment.     

Contaminant Metal Behaviour During Re-suspension of Sulphidic Estuarine Sediments

Sediment re-suspension experiments have been conducted to predict contaminants release from sediments to the water column, during dredging operations. In this context, polluted, anoxic estuarine sediments from Rio de Janeiro, SE Brazil, were suspended in oxygenated estuarine water, in laboratory experiments intended to simulate their dispersion by flood flow or dredging operations, in order to measure any release into solution of heavy metals originally present as sulphides that might suffer oxidation. Oxidation of sulphides to sulphate acidified the waters but only after at least 5 h of suspension. Furthermore, the oxidation of acid volatile sulphide (AVS) to sulphate was more rapid and only proceded to completion within 5 days, when large quantities of sulphide forming metals other than Fe were not present. In sediment heavily polluted with zinc, oxidation of AVS was slower and incomplete, resulting in soluble release of a much smaller fraction of the Zn present in the sediment and a maximum dissolved zinc concentration that was much lower than that resulting from less contaminated sediment. The maximum percentages of sulphide-bound metals appearing in solution at any time during re-suspension were low, less than 46% in all cases and typically less than 10%. These maxima were manifested only after acidification by sulphate formation. Appreciable metal dissolution would not occur in an estuary if dilution and dispersion separated the sediment from acid generated or if dredged material settled before acidification occurred.     

Evaluation of two bacterial delivery systems for in-situ remediation of PAH contaminated sediments

Intention, Goal and Background  Contaminated sediments represent a significant, worldwide environmental problem since they contain a mixture of different xenobiotics and heavy metals. The presence of mixed contamination presents a unique set of obstacles for remediation efforts. Often sediment remediation occurs as an ex-situ application (i.e., after dredging) in an attempt to minimize some of the problems. However, dredging poses it’s own issues. It does not address contaminated water and often material is not completely removed thereby leaving a long-term residual contamination source in the waterway. Objective  The potential of bio remediation to treat sediments contaminated with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and heavy metals was addressed. The primary objective was to assess two delivery mechanisms for microbial inoculation to facilitate in-situ remediation of PAH contaminated sediments. Methods  Simulated river beds were constructed to mimic the Mahoning River. Contaminated sediment from the river was added to each reactor at a uniform depth, followed by the addition of river water. Fifteen inoculation points were used in each simulated river bed to ensure adequate microbial populations. One tank was inoculated with an acclimated bacteria solution as a free suspension. The other tank was inoculated with an attached growth biofilm system. Sediment samples were taken throughout the experiment and the percent PAH degradation determined. Water characteristics (DO, pH, bacterial activity, etc.) were also tracked as corroborating evidence. Results and Discussion  The monitoring sites indicated that an attached growth system was more effective, and achieved a 99% PAH degradation efficiency at some of the sampling sites. Tracking individual PAH compounds also indicated a higher overall microbial activity with the attached growth system. This activity was evident by the formation and subsequent biodegradation of lower molecular weight degradation byproducts. However, more of the sediment area was treated by the free suspension inoculum due to the ease of microbial migration. Conclusions  The applicability of using an aerobic microbial consortium composed ofMycobacterium sp., Pseudomonas aeruginosa, andPseudomonas flourescens to treat contaminated sediment was demonstrated. In addition, it was found that introducing the consortium as an attached growth was more effective than when delivered as a free suspension. Recommendation and Outlook  The results demonstrated that the consortium was effective at treating the PAHs present in the contaminated soil. An additional study to evaluate the consortium’s effectiveness at remediating the PCB present in the sediment is warranted. Optimization of the consortium-nutrient combination could enable a treatment approach to effective for all the organic contaminants present. Although this would not address the heavy metals present in the sediment, it would afford a great opportunity at remediating a severely contaminated sediment system.     

Sediment Properties for Assessing the Erosion Risk of Contaminated Riverine Sites. An approach to evaluate sediment properties and their covariance patterns over depth in relation to erosion resistance. First investigations in natural sediments (11 pp)

Background, Aim and Scope   Riverine sediments store large quantities of hazardous contaminants, remaining a 'legacy of the past' world-wide. Natural events such as floods may cause the resuspension of polluted sediments and accordingly, the former immobilized contaminants might become bioavailable and toxic again. Hence, a comprehensive erosion risk assessment of contaminated sites is of crucial importance. The present study aimed to implement 'master-variables' for a reliable, easy-to-manage and economically more viable determination of stability in cohesive sediments. Materials and Methods: A wide range of physico-chemical (bulk density, water content, particle size, mineral composition, cation exchange capacity / CEC, total organic matter / TOC, liquid and plastic limits of a soil) and biological (macrofauna abundances, microalgal biomass and species composition, bacterial cell numbers, EPS fractions such as carbohydrates and proteins) properties were determined simultaneously over depth spanning the zone between 0-35 cm. The data were related to sediment stability, determined as the 'critical shear stress for mass erosion' in the SETEG (Stroemungskanal zur Ermittlung der tiefenabhaengigen Erosionsstabilitaet von Gewaessersedimenten) - flume. The investigations were done on natural sediments, thereby covering vertical (over depth), spatial (different study sites) and temporal (different seasons) aspects to ensure the transferability of the data. Here, first data originating from three contaminated reservoirs in the lock-regulated River Neckar / Germany are presented. Results: Comparison of the rather low critical shear stress values (resisting force of sediment, determined in SETEG) with the possibly occurring natural bottom shear stresses (attacking force, calculated for different hydraulic scenarios) at the three reservoirs indicated a severe risk of sediment erosion even under moderate hydraulic conditions and was not restricted to the surface. Critical shear stress was characterised by the following sediment properties of depth, grain size, CEC (Cation Exchange Capacity) and concentrations of TOC (Total Organic Carbon), proteins as well as carbohydrates (water- and resin-extractable). Firstly, biological stabilisation by extracellular polymeric substances (EPS) could be shown for riverine sediments, even over depth. Secondly, erosion resistance was determined by the inter-particles forces, an interplay of the biologically produced compounds constituting active surfaces and the binding capacity as well as charge densities of the sediments. The combined influence of sedimentological and biological properties on sediment stability over depth was assessed by PCA (Principal Component Analysis). Discussion: Hence, a better correlation coefficient between sediment stability and the master variables could be achieved (Main component II: Polymeric substances, R = 0.7, Main component III: Grain size, TOC, CEC, R = 0.9) compared to single correlations. Conclusions: The present paper revealed the combined influence of physico-chemical and biological properties on sediment stability over depth by simultaneous investigation and statistical evaluation. It can be shown, that inter-particle forces, determined by particles size classes, CEC, TOC and polymeric substances such as proteins and carbohydrates, affected sediment stability most. Thereby, the impact of biogenic sediment mediation on riverine sediment stabilisation became evident, even over depth, where mostly sedimentological parameters were considered as important before. Recommendations and Perspectives: The importance of a comprehensive risk assessment of contaminated riverine sites was again highlighted in the present study by the comparison of natural occurring bottom shear stresses with the determined sediment erosion resistance. If a realistic risk assessment is to be derived, the stabilizing potential of micro-organisms needs to be taken into account and the covariance patterns of biological and physico-chemical sediment properties have to be addressed.     

Sublethal effects of contaminated sediment on Arenicola marina

Purpose

The highest concentrations of environmental contaminants are generally found in marine sediments, and there is a need for knowledge concerning how and whether they affect sediment-dwelling organisms. This study aimed to assess sublethal effects in Arenicola marina exposed to two sediments from a contaminated fjord and two reference locations with different sediment characteristics.

Materials and methods

Duplicate contaminated sediments were used to investigate the robustness of current protocols for sediment testing. The two reference sediments, with different grain sizes and total organic carbon, were collected from the outer Oslofjord and the two contaminated sediments from Frierfjord. Polychaetes were exposed in quadruplicate sediment microcosms and sampled after 1, 2, 4 and 8?weeks of exposure. Oxidative stress resistance (total oxyradical scavenging capacity, TOSC) and components comprising the energy budget (cellular energy allocation, CEA) were determined for individual polychaetes.

Results and discussion

Arenicola maintained and increased body weights over the initial 4?weeks of exposure in all groups, except in one reference sediment (Elle). There were no differences between treatments in the scavenging capacity (TOSC). The most striking difference in how polychaetes partitioned energy resources was a difference in lipid and carbohydrate allocations for Arenicola held in the contaminated sediments over the initial weeks. Cellular respiration appeared to increase in polychaetes held in the Elle sediment and decreased for polychaetes held in the two Frierfjord sediments by weeks?4 and 8. In the overall CEA, this was offset by increased energy per weight stored in the Elle group, which resulted in an overall positive CEA for polychaetes held in that sediment, whereas polychaetes in the other treatments were close to neutral. Although CEA would thus indicate that Elle polychaetes had good health status, their body weight also decreased significantly over the experimental period compared to other treatments, indicating an overall negative effect.

Conclusions

This study has shown the importance of sediment characteristics when evaluating toxicity and how resource allocation can differ dramatically over a short time span in polychaetes held in similarly contaminated sediments. There were no clear effects of sediment contamination on CEA or TOSC in the polychaete A. marina. The findings are relevant for the design of both short- and long-term sediment studies.     

Environmental implications of magnetic measurements on recent sediments from lake Donghu,Wuhan

Mineral magnetic measurements have been made on three sediment cores from Lake Donghu, Wuhan, which reveal evidence for changes in magnetic properties of the sediments. It is suggested that the recent lake sediment profiles contain deposited magnetic minerals and atmospherically derived fly ash from industrial processes. In the cores, the record of ‘magnetite’ deposition shows that the environment of the lake has been affected by heavy industrial processes in intensity and range beginning from the 1950's onwards and remaining relatively uniform in the last decades. In Core I the record of ‘hematite’ deposition parallels that for influence of urban waste water input.     

Polycyclic Aromatic Hydrocarbons in the Sediments of the Milwaukee Harbor Estuary, Wisconsin, U.S.A.

From 1990 to 1994, a total of 21 sediment cores and 37 grab sediment samples were collected from the Milwaukee Harbor Estuary. Each sediment core was sectioned and dated using ²¹⁰Pb and¹³⁷ Cs radioisotope techniques. A total of 305 samples were analyzed for sixteen polycyclic aromatic compounds (PAHs). Grain size distribution, porosity, and total organic carbon content as measured by loss on ignition were also determined. The results provide a historical overview of the impact of industrialization in the Milwaukee area. Although highly variable, the concentration profile of PAHs show, in general, peaks in the 1950's through 1980's. The PAH concentrations have declined since then for most sediment cores. The current levels of total PAHs in most surface sediment samples range from 25 to 200 ppm. A few cores, some of which were collected in 1994, have an elevated PAH concentration at the surface. Toxicity of the surface sediments was evaluated by comparing with the benchmark values developed by the United States National Oceanic and Atmospheric Administration (NOAA). The most heavily contaminated area was found in the Kinnickinnic River between the Becher Street Bridge and the Wisconsin Wrecking Company Wharf. The highest total PAH concentration determined from seven vibra cores collected in this area ranges from 380 to 1000 ppm. The former Wisconsin Solvay Coke Company may have been a major point source of PAHs until the 1970's. Highway traffic and various industrial discharges also contribute to the sediment PAHs in this area.     

中国长江中下游地区浅水湖泊沉积物有机磷研究

Thirteen sediment core samples （0 10 cm） were taken from the seven lakes in the middle and lower reaches of the Yangtze River to determine the contents and distributions of organic phosphorus （P） fractions in the sediments of the shallow lakes in the area. The organic P fractions in the sediments were in the order of moderately labile organic P （MLOP） 〉 moderately resistant organic P （MROP） 〉 highly resistant organic P （HROP） 〉 labile organic P （LOP）, with average proportional ratios of 13.2：2.8：1.3：1.0. LOP, MLOP, and MROP were significantly related to the contents of total organic carbon （TOC）, water-soluble P （WSP）, algal-available P （AAP）, NaHCO3-extractable P （Olsen-P）, total P （TP）, organic P （OP）, and inorganic P （IP）. However, HROP was significantly related to OP and weakly correlated with TOC, WSP, AAP, Olsen-P, TP or IP. This suggested that organic P, especially LOP and MLOP in sediments, deserved even greater attention than IP in regards to lake eutrophication. In terms of organic P, sediments were more hazardous than soils in lake eutrophication. Although OP concentrations were higher in moderately polluted sediment than those in heavily polluted sediment, LOP and MLOP were higher in the heavily polluted sediment, which indicated that heavily polluted sediment was more hazardous than moderately polluted sediment in lake eutrophication.     

Deep-water scleractinian corals promote higher biodiversity in deep-sea meiofaunal assemblages along continental margins

Deep-water coral ecosystems are hot spots of biodiversity and provide habitats and refuges for several deep-sea species. However, their role in shaping the biodiversity of the surrounding open slopes is still poorly known. We investigated how meiofaunal biodiversity varies with and is related to the occurrence of deep-water living scleractinian corals and coral rubble in two deep-sea areas (the Rockall Bank, north-eastern Atlantic) and the Santa Maria di Leuca (central Mediterranean). In both areas, replicated sampling on alive and dead coral areas and from the adjacent slope sediments without corals (at the same and increasing depths) allowed us to demonstrate that sediments surrounding the living corals and coral rubble were characterised by higher meiofaunal biodiversity (as number of higher taxa, and nematode species richness) than the slope sediments. Despite the soft sediments surrounding the living coral having a higher nutritional value than those not associated with corals, with the opposite seen for coral rubble, the presence of both alive and dead corals had a significant effect on nematode assemblages. Our data suggest that, due particularly to the effects on habitat heterogeneity/complexity, both living coral and coral rubble promoted higher biodiversity levels than in surrounding slope sediments. We conclude that the protection of deep-water corals can be crucial to preserve the biodiversity of surrounding open slopes, and that the protection of dead corals, a so-far almost neglected habitat in terms of biological conservation, can further contribute to the maintenance of a high deep-sea biodiversity along continental margins.     

Sediment and society: an approach for assessing management of contaminated sediments and stakeholder involvement in Norway

Introduction

Management options for large-scale contaminated sediment remediation projects can be challenging with regard to competing stakeholder interests. This has become apparent during the Oslofjord sediment remediation project (2005–2009) which caused considerable public discussion.

Background

To learn from this project, the ‘Sediment and society’ project was initiated to develop a collaborative approach that will incorporate local and scientific knowledge in order to achieve mutual gains, win-win outcomes for the stakeholders, in the management of contaminated marine sediments.

Method development

The project focuses on two Norwegian harbours: Oslo Harbour and Bergen Harbour. The Oslo Harbour case has been analysed ex-post, using elements of risk governance: participation, communication, information/knowledge and risk perception. The Bergen Harbour case is focused on the establishment of a citizens' jury as well as a stakeholder panel in Bergen Harbour.

Preliminary results and observations

Thus far, the results suggest three important commonalities or challenges for stakeholder involvement: (1) how to include people who have important management information and local knowledge, but not much influence in the decision-making process; (2) how to secure resources to ensure participation and (3) how to engage and motivate stakeholders to participate early in the sediment remediation planning process.     

Mechanisms and Factors Influencing Adsorption of Microcystin-LR on Biochars

With industrialization, great amounts of trace elements and heavy metals have been excavated and released onto the surface of the earth and dissipated into the environments. Rapid screening technology for detecting major and trace elements as well as heavy metals in variety of environmental samples has been most desired. The objectives of this study were to determine the detection limits, accuracy, repeatability, and efficiency of an X-ray fluorescence spectrometer (Niton XRF analyzer) in comparison to the traditional analytical methods, inductively coupled plasma optical emission spectrometer (ICP-OES) in screening of major and trace elements of environmental samples including estuary soils and sediments, contaminated soils, and biological samples. XRF is a fast and non-destructive method for measuring the total concentration of multi-elements simultaneously. Contrary to ICP-OES, XRF analyzer is characterized by the limited preparation required for solid samples, non-destructive analysis, increased total speed and high throughout, decreased production of hazardous waste, and low running costs as well as multi-elemental determination and portability in the fields. The current comparative study demonstrates that XRF is a good rapid, non-destructive screening method for contaminated soils, sediments, and biological samples containing high concentrations of major and trace elements. Unfortunately, XRF does not have sensitive detection limits for most trace elements as ICP-OES, but it may serve as a rapid screening tool for locating hot spots in uncontaminated field soils and sediments, such as in the US Department of Energy’s Oak Ridge site.     

Hazard identification of contaminated sites—ranking potential toxicity of organic sediment extracts in crustacean and fish

Background, aim, and scope  It is well known that contaminated sediments represent a potential long-term source of pollutants to the aquatic environment. To protect human and ecosystem health, it is becoming common to remediate contaminated sites. However, the great cost associated with, e.g., dredging in combination with the large numbers of contaminated sites makes it crucial to pinpoint those sites that are in greatest need of remediation. In most European countries, this prioritization process has almost exclusively been based on chemical analyses of known substances; only seldom toxicity data has been considered. The main objective of the current study was therefore to develop a tool for hazard identification of sediment by ranking potential toxicity of organic sediment extracts in a crustacean and a fish. A secondary objective was to investigate the difference in potential toxicity between compounds with different polarities. Materials and methods  Early life stages of the crustacean Nitocra spinipes and the fish Oncorhynchus mykiss, which represent organisms from different trophic levels (primary and secondary consumer) and with different routes of exposure (i.e., ingestion through food, diffusive uptake, and maternal transfer), were exposed to hexane and acetone fractions (semi-polar compounds) of sediment from five locations, ranging from heavily to low contaminated. Preliminary tests showed that the extracts were non-bioavailable to the crustacean when exposed via water, and the extracts were therefore loaded on silica gel. Rainbow trout embryos were exposed using nano-injection technique. Results and discussion  Clear concentration–response relationships of both mortality and larval development were observed in all tests with N. spinipes. Also for rainbow trout, the observed effects (e.g., abnormality, hemorrhage, asymmetric yolk sac) followed a dose-related pattern. Interestingly, our results indicate that some of the locations contained toxic semi-polar compounds, which are normally not considered in risk assessment of sediment since they are focused on compounds isolated in the hexane fraction. Conclusions  The ranking of the five sediments followed the expected pattern of potential toxicity in both organisms, i.e., sediments with known pollution history caused major effects while reference sediments caused minor effects in the two test systems. Silica gel turned out to be an excellent carrier for exposure of N. spinipes to very hydrophobic and otherwise non-bioavailable sediment extracts. Recommendations and perspectives  Since both test systems demonstrated that a substantial part of the potential toxicity was caused by semi-polar compounds in the acetone fractions, this study enlightens our poor understanding of which compounds are causing adverse effects in environmental samples. Therefore, by investigating potential toxicity (i.e., hazard identification) as a first screening step in prioritizing processes, these implications could be avoided. For proper sediment risk assessment, we however recommend whole sediment toxicity tests to be used for selected sites at following tiers.     

The Landfill of TBT Contaminated Harbour Sludge on Rinsing Fields—a Hazard for the Soil Fauna? Risk Assessment with Earthworms

Despite the cutback of the use of antifouling paints containing tributyltin (TBT), harbour sediments are still “hot spots” for organotin pollution, which is one of the most toxic substances for aquatic organisms. Harbours have to be freed constantly of suspended sediments, to guarantee unhindered shipping. The deposition of these TBT contaminated sediments on rinsing fields is supposed to comprise a minimisation of the risk potential for humans and environment. To investigate if TBT contaminated sediment might present a hazard to the existing soil fauna, a risk assessment with earthworms was performed. The original TBT contaminated sediment induced 94% mortality, compared to 2% in the uncontaminated standard Lufa soil. It was assumed that the high salinity (23 dS/m) was the reason for the mortality rather than the TBT concentration of 600 μg/kg soil (dry weight). To reduce the soil salinity, the TBT substrate was first washed with deionised water and then mixed with the uncontaminated artificial OECD soil (=TBT_mix), which resulted, however, in a lower TBT concentration (132 μg/kg soil dw.). The uncontaminated OECD reference soil resulted in high earthworm mortality (34%). Despite the reduced salinity (10 dS/m) and lower TBT concentration, the TBT_mix substrate induced high mortality rates (42%), reduced reproduction (17% compared to the control) and resulted in a significant substrate avoidance of 92%. Consequently, the landfilling of the TBT contaminated harbour sludge might (i) present a hazard to the existing soil fauna at the rinsing fields due to high salinity and the TBT contamination, and (ii) a quick recolonisation of the contaminated substrate by earthworms can not be expected.     

The Impact of a Lignite Seam on Contaminated Groundwater in the Aquifer System of the Bitterfeld Region

Until 1990 the Bitterfeld region was heavily polluted by mining,an obsolete chemical industry and the uncontrolled deposition ofchemical wastes. The groundwater is extensivly contaminated inthe area of a disused chemical factory which once produced andapplied halogenated compounds on a large scale. At the researcharea in Bitterfeld, highly mobile chlorinated aliphatics andaromatics have been detected in both groundwater and sediments,especially in a lignite seam. The modern analytical method ofsolid-phase micro extraction (SPME) was successfully used toanalyse the pollution level of groundwater and sediments. Thelignite seam was found to have accumulated large quantities ofhalogenated hydrocarbons functioning as a giant adsorptionfilter, and hence recording past groundwater contamination.The vertical and lateral pollution profiles of sediments and thedistribution coefficients between lignite and groundwater atequilibrium conditions were determined for the key components.The consequences of the present situation for the progressivegroundwater quality of the quaternary aquifer are assessed in aforthcoming article.     

Salt marsh rhizosphere affects microbial biotransformation of the widespread halogenated contaminant tetrabromobisphenol-A (TBBPA)

Estuarine sediments are the repository for a wide range of contaminants. Anthropogenic impacts and variations in the belowground biomass of salt marsh plants potentially select for different sediment microbial communities with different functional capabilities, including the ability to biotransform anthropogenic contaminants. There are large differences in both root morphology and the amount of fine root biomass of Spartina alterniflora and Phragmites australis; Spartina is the species commonly used to replace Phragmites in northeastern US salt marsh restoration projects. Our study compared the effect of these two macrophyte species on sediment microbial communities responsible for the biotransformation of the halogenated flame retardant tetrabromobisphenol A (TBBPA). Sediments were obtained from contaminated and uncontaminated salt marsh field sites in New Jersey. Anaerobic methanogenic sediment microcosms were established and incubated for up to 130 days. TBBPA was reductively dehalogenated resulting in the transient formation of two intermediates, identified as tribromobisphenol A and dibromobisphenol A, and the formation and accumulation of bisphenol A (BPA) as the end product. Spartina sediments from both sites were found to dehalogenate TBBPA more rapidly than the Phragmites or unvegetated sediments, resulting in greater production of BPA. Microbial community diversity as measured by in situ sediment phospholipid fatty acid (PLFA) composition prior to TBBPA exposure, was found to be higher in the uncontaminated sediments; differences in microbial PLFA diversity were not seen in contaminated sediments associated with either the different plant species or unvegetated sediment. The results of this study demonstrate that these two plant species affected sediment microbial community function with respect to dehalogenation capabilities, even though the disturbed and undisturbed sediments varied in microbial community composition.