Sources and transport of hydrocarbons in sediments from the Changjiang River Estuary, China.
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Biomarkers↗
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Geochemistry of bed and suspended sediment in the Mississippi river system: provenance versus weathering and winnowing.
Stream-bed sediment for the size fraction less than 150 microm, examined in 14,000 samples collected mostly from minor tributaries to the major rivers throughout the Mississippi River drainage system, is composed of 5 mineral fractions identified by factor analysis-Al-silicate minerals, quartz, calcite and dolomite, heavy minerals, and an Fe-Mn fraction. The Al-silicate fraction parallels its distribution in the regolith, emphasizing the local sediment source as a primary control to its distribution. Quartz and the heavy-mineral fraction, and associated trace elements, exhibit a complementary distribution to that of the Al-silicate fraction, with a level of enrichment in the bed sediment that is achieved through winnowing and sorting. The carbonate fraction has a distribution suggesting its dissolution during transport. Trace elements partitioned onto the Fe-Mn, possibly amorphous oxyhydride, fraction are introduced to the streams, in part, through human activity. Except for the heavy-mineral fraction, these fractions are identified in suspended sediment from the Mississippi River itself. Although comparison of the tributary bed sediment with the riverine suspended sediment is problematic, the geochemistry of the suspended sediment seems to corroborate the interpretation of the geochemistry of the bed sediment.
Geologic Sediments↗
Bioleaching of heavy metals from contaminated sediment by indigenous sulfur-oxidizing bacteria in an air-lift bioreactor: effects of sulfur concentration.
The effects of sulfur concentration on the bioleaching of heavy metals from the sediment by indigenous sulfur-oxidizing bacteria were investigated in an air-lift reactor. Increasing the sulfur concentration from 0.5 to 5 g/l enhanced the rates of pH reduction, sulfate production and metal solubilization. A Michaelis-Menten type equation was used to explain the relationships between sulfur concentration, sulfate production and metal solubilization in the bioleaching process. After 8 days of bioleaching, 97-99% of Cu, 96-98% of Zn, 62-68% of Mn, 73-87% of Ni and 31-50% of Pb were solubilized from the sediment, respectively. The efficiency of metal solubilization was found to be related to the speciation of metal in the sediment. From economical consideration, the recommended sulfur dosage for the bioleaching of metals from the sediment is 3g/l.
Bioreactors↗
Box coring artifacts in sediments affected by a waste water outfall.
Variations in porosity of surface sediments are often the major cause of sediment loss during gravity and box coring. Sediments with a high content of organic matter usually have higher porosity, and thus, lower resistance (strain) towards mechanical disturbance. Here, we demonstrate that box coring artifacts (i.e. sediment loss and core shortening) can be produced in sediments from the Palos Verdes (PV) shelf, which in the past had received relatively high loads of organic carbon (OC) enriched particulate matter originating from the Whites Point outfall that had created a high porosity layer at depth. This has been overlooked as a possibility for obtaining low estimates of sediment and pollutant accumulation rates. Since any such sediment loss during coring can lead to serious underestimates of sedimentation rates, our results here may have important implications for any attempts at reconstructing pollutant fluxes and histories in these coastal marine sediments.
Artifacts↗
New concepts in ecological risk assessment: where do we go from here?
Through the use of safety factors, the use of single-species test data has been adequate for use in protective hazard assessments and criteria setting but, because hazard quotients do not consider the presence of multiple species each with a particular sensitivity or the interactions that can occur between these species in a functioning community, they are ill-suited to environmental risk assessment. Significant functional redundancy occurs in most ecosystems but this is poorly considered in single-species tests conducted under laboratory conditions. A significant advance in effects assessment was the use of the microcosm as a unit within which to test interacting populations of organisms. The microcosm has allowed the measurement of the environmental effect measures such as the NOAEC(community) under laboratory or field conditions and the application of this and other similarly derived measures to ecological risk assessment (ERA). More recently, distributions of single-species laboratory test data have been used for criteria setting and, combined with distributions of exposure concentrations, for risk assessment. Distributions of species sensitivity values have been used in an a priori way for setting environmental quality criteria such as the final acute value (FAV) derived for water quality criteria. Similar distributional approaches have been combined with modeled or measured concentrations to produce estimates of the joint probability of a single species being affected or that a proportion of organisms in a community will be impacted in a posteriori risk assessments. These techniques have not been widely applied for risk assessment of dredged materials, however, with appropriate consideration of bioavailability and spatial and nature of the data these techniques can be applied to soils and sediments.
Animals↗
Mercury pollution sources in sediments of Patos Lagoon Estuary, Southern Brazil.
Present study has continued the investigation on distribution of mercury in estuarine sediments of Patos Lagoon which began whilst assessing the after-effect of enormous accidental discharge of sulfuric acid into the estuary. An attempt to evaluate the contribution of anthropogenic effluents on mercury pollution in sediments was undertaken. The effluents from Rio Grande City sewages were categorized into four groups based on their sources. Comparison of mercury concentrations from those, indicated that domestic effluent was prevalent. Apparent geographic controls of effluent locations enriched in mercury on zones of polluted estuarine sediments were also revealed. Insufficient control on waste collecting and absence of sewage treatment are considered the principal causes of mercury pollution in estuarine sediments.
Brazil↗
Contribution of different sources to the pollution of wet weather flows in combined sewers.
Experiments performed on "Marais" catchment, in central Paris, aimed to follow up the quality of wet weather flows from the entry to the exit of a combined sewer network. SS, VSS, COD, BOD5, Cd, Cu, Pb, Zn concentrations were measured for an important number of rain events in roof, yard, street runoff, as well as in dry and wet weather flows at the catchment outlet. Mass entry-exit totals, at the scale of the catchment, were calculated over 31 rain events in order to evaluate the contribution of different types of runoff, of sanitary sewage and of sewer sediments to the total wet weather pollutant loads at the catchment outlet. The erosion of in-sewer pollutant stocks was found to be the main source of particles and of organic matter in wet weather flows, whereas heavy metal loads mainly originated from roof runoff, due to the corrosion of metallic roofs. Particles eroded inside the sewer during rain events were found to be quite different from the particles constituting the main part of sewer sediments: they are organic and biodegradable, with rather important settling velocities and seem to accumulate during dry weather periods. A change of the chemical form of heavy metals was noticed during the transport in the sewer and it is suspected that a fraction of the dissolved metals from the runoff is adsorbed on sewer sediments.
Cadmium↗
Heavy metal pollution in sediments of the Pasvik River drainage.
The purpose of this paper is to study the regional impacts of heavy metals (Ni, Cu, Co, Zn, Cd, Pb, Hg) on the watershed of the Pasvik River. On the basis of sediment investigations at 27 stations of the watershed, background concentrations of the heavy metals, vertical distribution of heavy metals in sediments, heavy metal concentrations in surface sediments, contamination degree, and risk index were determined. The atmospheric emissions of Ni, Cu, Co, Zn, Cd and Hg from the smelters and waste waters from tailing dams and mines of the Pechenganickel Company are likely to be the main sources of increasing concentrations observed in recent sediments of the lower river reaches. Lead showed a different pattern from the other heavy metals--increasing Pb concentrations in the upper sediment layers towards the Norwegian side.
Environmental Monitoring↗
Identification and quantitation of dinaphthylsulfones in particulate matter of the Elbe river, Germany. Part VI of organic compounds as contaminants of the Elbe river and its tributaries.
Gas chromatographic-mass spectrometric (GC/MS) analysis of particulate matter of the Elbe river and its tributaries Havel, Spree and Mulde revealed a group of three dinaphthylsulfone isomers as sedimentary and suspended particulate matter (SPM) contaminants. The mass spectra of dinaphthylsulfones are characterized by the molecular ion (m/z 318), and the naphthyl fragment ion m/z 127. Losses of HSO(2) and C(10)H(7)O from the molecular ion lead to different mass spectra for each isomer. The gas phase infrared spectra exhibit isomer specific bands in the spectral region between 900 and 700 wave numbers. A synthetic mixture of dinaphthylsulfones was used for isomer identification and the assignment of the gas chromatographic retention behaviour of the dinaphthylsulfone isomers. Quantitative GC/MS analysis of dinaphthylsulfones in 44 sediment and SPM samples provided comprehensive information on the overall distribution and distinct sources of dinaphthylsulfones in the Elbe river drainage system. The results indicate emissions of these compounds over prolonged times and their environmental stability in anaerobic sediments.
Environmental Monitoring↗
Solid phase partitioning of metals in managed retreat soils: field changes over the first year of tidal inundation.
Sequential extraction methods were used to determine the effect of saline inundation on partitioning behaviour of metals in soils at Orplands Managed Retreat site, Essex, UK. A suite of metals (Al, Ca, Cr, Cu, Fe, K, Li, Mn, Ni, Pb and Zn) were analysed in sequential extracts from samples of soil cores extracted immediately before breaching of sea walls in 1995 and 1 year after. Generally, partitioning of most metals was dominated by associations with the residual fraction and an absence of associations with the exchangeable fraction indicating a relatively uncontaminated environment. Changes in partitioning were predominantly limited to the top 8 cm of the soil profile where a decaying mat of vegetation from the pre-inundation surface resulted in high moisture contents and low redox potentials. In this zone, the predominance of metal associations with the residual fraction was replaced by associations with more labile fractions. In the surface layer deposited after breaching, Ca was dominantly associated with the carbonate fraction, which indicates biogenic import from adjacent estuarine sediments.
Geologic Sediments↗
Progressive changes in water and sediment quality in a wetland system for control of highway runoff.
Innovative wetland based systems were designed and installed on the Newbury Bypass, Berkshire, England to provide flow balancing and pollution control for road runoff. The systems were monitored over 18 months to evaluate performance, pollutant removal processes and offer improved design and operation codes for this new application of wetlands. Water quality, sediment accumulation rates, and metal concentrations in size-fractionated, settling solids and deposited sediments were determined in parts of the system to provide information on spatial and temporal variability. The results presented here show that over the long term, there were progressive changes in parts of the system for BOD and COD and for metal concentrations in the sediment fractions, which occurred with linear (or semi log-linear) rates, despite variability in flow rates, retention times and in pollutant loading to the system. Future work will continue monitoring to increase the data set, examine possible processes contributing to the regression constants, and test the potential use of the regressions in system modelling. Attempts at modelling road runoff treatment using wetlands must allow for progressions, since the systems can only be effective if they retain removed metals in the sediment sink.
England↗
Isotope fractionations in the terrestrial carbon cycle: a brief overview.
The bias in favour of isotopically light carbon inherent in biological carbon fixation has brought about an isotopic disproportionation of primordial (mantle-derived) carbon on a global scale, causing an enrichment of 12C in reduced (biogenic) carbon and a concomitant accumulation of the heavy complement (13C) in the residual oxidized (inorganic) carbon pool. As a result, the terrestrial carbon cycle has gone bipartite, comprising an organic branch of isotopically light carbon, and an inorganic branch made up of 13C-enriched carbon (mostly in the form of carbonate). The isotopic disparity between the two principal terrestrial carbon species can be traced back over 3.8 Gyr of Earth history, attesting to a biological modulation of the carbon cycle since the time of formation of the oldest sediments.
Biomass↗
Contaminant bioavailability in soil and sediment.
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Animals↗
Sorption and displacement of pyrene in soils and sediments.
Sorption isotherms of pyrene on soils and sediments were examined to understand its sorption behavior. All systems examined exhibited nonlinear sorption. Sorption nonlinearity was found to be a function of the polarity index of soil/sediment organic matter (SOM), suggesting that the degree of condensation of SOM, characterized by its polarity index, was correlated with the sorption behavior of pyrene. The polarity index of SOM could be a new factor for explaining the sorption nonlinearity. The sorption affinity of two soils and two sediments for pyrene increased with decreasing SOM polarity. A higher sorption affinity in the two soils was associated with a higher degree of condensation of SOM compared to that of the two sediments. A displacement test was performed after pyrene sorption using phenanthrene as a displacer. Pyrene was displaced in all systems examined, and nonlinearity became less pronounced after displacement. Such an increase in isotherm linearity implied that sorption site energies became more homogeneous after displacement. Furthermore, the site energy distribution IE*) derived from the Freundlich model parameters showed that energy reduction of high-energy sites was more significant than that of low-energy sites after displacement. In addition, a decrease in sorption capacity after displacement could be ascribed to the partial depletion of sorption sites by the displacer. The displacement data indicated that the cocontaminant can have potential effects on the fate and bioavailability of anthropogenic organic pollutants sorbed in soils and sediments, thus affecting their exposure risks.
Geologic Sediments↗
Possible biological significance of contaminated sediments in Port Jackson, Sydney, Australia.
Comprehensive investigations of estuaries in central New South Wales has identified Port Jackson as the most contaminated waterway on the eastern seaboard of Australia. Extensive areas of the estuary are mantled in sediment containing high concentrations of a large range of metallic and organic contaminants. Although extensive, this database does not provide an effective basis for determining the potential adverse effects of chemicals on living resources. In the absence of any ecotoxicological information, the recently published (1999) draft Australian and New Zealand Environmental and Conservation Council (ANZECC) sediment quality guidelines have been used to assess possible adverse biological effects of these toxicants. The ANZECC guidelines use the lower effects range of the widely used U. S. National Oceanic and Atmospheric Administration (NOAA) scheme to identify potentially contaminated sediment and as a threshold to trigger for additional investigative work. This guideline level has been used in the current study to assess possible toxicity of contaminated sediments in Port Jackson. It is estimated that sediments in approximately 26% of the estuary, mainly the upper parts of the harbour and much of the central harbour, have a 67% probability of being toxic. Sediments in the central harbour and a major tributary, the Middle Harbour, comprising about 40% of the estuary, have a 13 to 25% probability of toxicity. All sediments in the harbour, except at the mouth of the estuary, would require additional environmental assessment based on the proposed draft ANZECC sediment quality guidelines.
Ecosystem↗
Monitoring of the natural environment by chemical speciation of elements in aerosol and sediment samples.
The development of a monitoring network for chemical speciation of elements of aerosol and sediment samples collected at Lake Balaton has been carried out. Sequential leaching procedures for the determination of the distribution of elements in aerosols (3 steps) and sediments (4 steps) were used. These methods were recently successfully applied to describe environmentally mobile and stable fractions of toxic metals. In aerosol matrices the partition of elements was accomplished by particle size and chemical bonding. In sediments the distribution was performed by chemical bonding. The processes are called fractionation of elements. Particular attention was paid to distinguishing between environmentally mobile and environmentally immobile fractions because these represent the two extreme modes by which the metals are bound to solid matrices. The monitoring objectives were to assess pollution effects on man and his environment and to identify any possible cause and effect relationship between pollutant concentrations and health effects. The results of dry and wet deposition rates showed that most of the toxic metals were dissolved in an aqueous phase and the wet deposition played an important role. It has been found that, while the concentration of Cd and Pb in aerosols is low (0.7 and 29 ng m(-3), respectively), environmentally mobile fractions are considerable. Based upon the data it can be concluded that the effect of the anthropogenic sources on the quality of the lake is minor. This has been the first attempt to correlate speciation results between aerosols and sediments.
Aerosols↗
Global intercomparison for the determination of chlorinated pesticides, PCBs and petroleum hydrocarbons in sediment sample IAEA-417.
A world-wide interlaboratory comparison exercise was organised using a lagoon sediment as sample material (IAEA-417) for the analyses of chlorinated pesticides, PCB congeners and petroleum hydrocarbons. The sample material was analysed by 97 laboratories from 46 countries, representing a rather wide distribution for such an interlaboratory comparison exercise. Whereas quite variable results were reported for most chlorinated pesticides, more consistent interlaboratory results were obtained for PCB congeners and polycyclic aromatic hydrocarbons (PAHs). Nevertheless, many laboratories reported results in sufficiently dose agreement that after statistical screening of the data, consensus values were obtained for the concentration of several analytes in this sediment sample. The results allow reference concentration values to be assigned for several analytes. Thus, the sediment sample IAEA-417 can be used as a reference material for quality control of data in the determination of chlorinated compounds and petroleum hydrocarbons in moderately polluted sediments.
Environmental Monitoring↗
In situ detection of bacteria in continuous-flow cultures of seawater sediment suspensions with fluorescently labelled rRNA-directed oligonucleotide probes.
rRNA-targeted and fluorescently labelled oligonucleotide probes were used to study the composition of natural bacterial populations in continuous-flow cultures of seawater sediment suspensions. The cultures were run as enrichment cultures with increasing dilution rates, and hexadecane as the sole carbon source. Total cell numbers were analysed by counting DAPI (4',6-diamidino-2-phenylindole)-stained cells. To differentiate the population composition, oligonucleotide probes for eubacteria, for Cytophaga/Flavobacteria, and for four subclasses of the Proteobacteria (alpha, beta, gamma and delta) were used. About 40-80% of the DAPI-stained cells could be detected with the EUB338 probe. Moreover, it was possible to detect a shift in the composition of the natural bacterial population with increasing dilution rate of the continuous culture, from large amounts of Cytophaga/Flavobacteria to large numbers of members of the gamma-Proteobacteria. The cell recovery rate for bacteria labelled with specific oligonucleotide probes was analysed with defined cell numbers of Rhodospirillum rubrum, Comamonas testosteroni and Desulfovibrio vulgaris subsp. vulgaris introduced into the seawater sediment suspension, and was determined to be 13.9-33.5%. The standard deviation determined for this method applied to sediment suspensions was +/- 8.3%. The results suggest that the application of the in situ hybridization technique allows a good insight into the structure of populations growing in sediment suspensions.
Alkanes↗