Nonequilibrium of Organic Compounds in Sediment - Water systems. Consequences for Risk Assessment and Remediation Measures
Noort, P.C.M. van; Koelmans, A.A. - \ 2012
Environmental Science and Technology 46 (2012)20. - ISSN 0013-936X - p. 10900 - 10908.
polycyclic aromatic-hydrocarbons - equilibrium passive samplers - contaminated sediments - pore-water - lumbriculus-variegatus - hyalella-azteca - polychlorinated-biphenyls - amphiura-filiformis - harbor sediments - matter quality
In many cases, sediment risk assessment, and remediation rely on the assumption of equilibrium between chemical concentrations in sediment pore water and overlying surface water and thus rely on pore water concentrations only and do not additionally include assessment of the overlying water concentration. Traditionally, the validity of this assumption was insufficiently documented due to a lack of data. Recent studies using passive samplers, however, provided sufficient data for the first systematic evaluation of the extent of disequilibrium between sediment pore water and overlying surface water. Recent bioaccumulation studies reveal uncertainty as to which of these concentrations govern bioaccumulation by benthic organisms. Here, we provide the first review of studies measuring disequilibrium identifying general patterns and implications for the aforementioned areas of application. In most studies on water/sediment (dis)equilibrium, sediment pore water and overlying surface water are close to equilibrium. For lower molecular weight PAHs, overlying water concentrations tended to be relative low, which is tentatively ascribed to biodegradation in the water column. Substantial nonequilibrium was observed at some hot-spot locations such as in semistagnant harbors. In such cases, efficacy of sediment remediation measures to improve overlying water quality can be questioned because differences between overlying water concentrations at the hot-spots and those at reference locations typically are small. For nonequilibrium situations and some benthic taxa, exposure may be determined best by pore water concentrations. Improving our understanding in this area may further improve risk assessment of contaminated sediments.
Transfer functions for solid solution partitioning of cadmium for Australian soils
Vries, W. de; Mc Laughlin, M.J. ; Groenenberg, J.E. - \ 2011
Environmental Pollution 159 (2011)12. - ISSN 0269-7491 - p. 3583 - 3594.
metal-ion activities - contaminated soils - humic substances - organic-matter - heavy-metals - surface waters - fresh-waters - pore-water - copper - speciation
To assess transport and ecotoxicological risks of metals, such as cadmium (Cd) in soils, models are needed for partitioning and speciation. We derived regression-based “partition-relations” based on adsorption and desorption experiments for main Australian soil types. First, batch adsorption experiments were carried out over a realistic range of dissolved Cd concentrations in agricultural soils in Australia. Results showed linear sorption relationships, implying the adequacy of using Kd values to describe partitioning. Desorption measurements were then carried out to assess in-situ Kd values and relate these to soil properties The best transfer functions for solid–solution partitioning were found for Kd values relating total dissolved Cd concentration to total soil Cd concentrations, accounting for the variation in pH, SOM contents and DOC concentrations. Model predictions compared well with measurements of an independent data set, but there was a tendency to underestimate dissolved Cd concentrations of highly polluted soils.
Maud Rise - a snapshot through the water column
Brandt, A. ; Bathmann, U. ; Brix, S. ; Florentino De Souza Silva, A.P. ; Franeker, J.A. van - \ 2011
Deep-Sea Research. Part II, tropical studies in oceanography 58 (2011)19-20. - ISSN 0967-0645 - p. 1962 - 1982.
eastern weddell gyre - southern-ocean - deep-sea - atlantic sector - antarctic krill - carbon fluxes - drake passage - 1st insights - pore-water - pack-ice
The benthic fauna was investigated during the expedition ANT-XXIV/2 (2007/08) in relation to oceanographic features, biogeochemical properties and sediment characteristics, as well as the pelagic, benthic pelagic and air-breathing fauna. The results document that Maud Rise (MR) differs distinctly from surrounding deep-sea basins investigated during previous Southern Ocean expeditions (ANDEEP 2002, 2005). Considering all taxa, the overall similarity between MR and adjacent stations was low (20% Bray-Curtis-Similarity), and analyses of single taxa show obvious differences in species composition, abundances and densities. The composition and diversity of bivalves of MR are characterised by extremely high abundances of three species, especially the small sized Vesicomya spp. Exceptionally high gastropod abundance at MR is due to the single species Onoba subantarctica wilkesiana, a small brooder that may prey upon abundant benthic foraminiferas. The abundance and diversity of isopods also show that one family, Haplomunnidae, occurs with a surprisingly high number of individuals at MR while this family was not found at any of the 40 bathyal and abyssal ANDEEP stations. Similarly, polychaetes, especially the tube-dwelling, suspension-feeder fraction, are represented by species not found at the comparison stations. Sponges comprise almost exclusively small specimens in relatively high numbers, especially a few species of Polymastiidae. Water-column sampling from the surface to the seafloor, including observations of top predators, indicate the existence of a prospering pelagic food web. Local concentrations of top predators and zooplankton are associated with a rich ice-edge bloom located over the northern slope of MR. There the sea ice melts, which is probably accelerated by the advection of warm water at intermediate depth. Over the southern slope, high concentrations of Antarctic krill (Euphausia superba) occur under dense sea ice and attract Antarctic Minke Whales (Balaenoptera bonaerensis) and several seabird species. These findings suggest that biological prosperity over MR is related to both oceanographic and sea-ice processes. Downward transport of the organic matter produced in the pelagic realm may be more constant than elsewhere due to low lateral drift over MR
Transfer functions for solid-solution partitioning of cadmium, copper, nickel, lead and zinc in soils: derivation of relationships for free metal ion activities and validation with independent data
Groenenberg, J.E. ; Römkens, P.F.A.M. ; Comans, R.N.J. ; Luster, J. ; Pampura, T. ; Shotbolt, L. ; Tipping, E. ; Vries, W. de - \ 2010
European Journal of Soil Science 61 (2010)1. - ISSN 1351-0754 - p. 58 - 73.
dissolved organic-matter - donnan membrane technique - contaminated soils - heavy-metals - sandy soil - chemical speciation - trace-metals - pore-water - ph - cu
Models to predict the solid-solution partitioning of trace metals are important tools in risk assessment, providing information on the biological availability of metals and their leaching. Empirically based models, or transfer functions, published to date differ with respect to the mathematical model used, the optimization method, the methods used to determine metal concentrations in the solid and solution phases and the soil properties accounted for. Here we review these methodological aspects before deriving our own transfer functions that relate free metal ion activities to reactive metal contents in the solid phase. One single function was able to predict free-metal ion activities estimated by a variety of soil solution extraction methods. Evaluation of the mathematical formulation showed that transfer functions derived to optimize the Freundlich adsorption constant (Kf), in contrast to functions derived to optimize either the solid or solution concentration, were most suitable for predicting concentrations in solution from solid phase concentrations and vice versa. The model was shown to be generally applicable on the basis of a large number of independent data, for which predicted free metal activities were within one order of magnitude of the observations. The model only over-estimated free-metal ion activities at alkaline pH (>7). The use of the reactive metal content measured by 0.43 m HNO3 rather than the total metal content resulted in a close correlation with measured data, particularly for nickel and zinc
Uptake of sediment-bound bioavailable polychlorobiphenyls by benthivorous carp (Cyprinus carpio)
Moermond, C.T.A. ; Roozen, F.C.J.M. ; Zwolsman, J.J.G. ; Koelmans, A.A. - \ 2004
Environmental Science and Technology 38 (2004)17. - ISSN 0013-936X - p. 4503 - 4509.
sediment - biologische beschikbaarheid - polychloorbifenylen - benthos - karper - zoetwatervissen - meren - waterinvertebraten - chemicaliën - opname (uptake) - organische scheikunde - ecotoxicologie - waterbodems - sediment - bioavailability - polychlorinated biphenyls - benthos - carp - freshwater fishes - lakes - aquatic invertebrates - chemicals - uptake - organic chemistry - ecotoxicology - water bottoms - hydrophobic organic contaminants - aquatic food webs - contact time - pore-water - ingested sediment - extraction - lake - pollutants - fish
It is unclear whether accumulation of sediment-bound chemicals in benthivorous fish depends on the degree of sequestration in the sediment like it does for invertebrates. Here, we report on the potential of slow and fast desorbing sediment-bound polychlorobiphenyl (PCB) fractions for accumulation in carp (Cyprinus carpio) in lake enclosures treated with different nutrient doses
It is unclear whether accumulation of sediment-bound chemicals in benthivorous fish depends on the degree of sequestration in the sediment like it does for invertebrates. Here, we report on the potential of slow and fast desorbing sediment-bound polychlorobiphenyl (PCB) fractions for accumulation in carp (Cyprinus carpio) in lake enclosures treated with different nutrient doses. Routes of PCB uptake were quantitatively evaluated for 15 PCBs (log K-0W range 5.6-7.8) using model analysis. Fast-desorbing PCB fractions in the sediment were defined as the ratio of 6-h Tenax-extractable to (total) Soxhlet-extractable concentrations. These fractions varied between 4 and 22% and did not show a clear trend with log K-0W. However, bioaccumulation of PCBs in carp correlated much better with Tenax-extractable concentrations than with total-extractable concentrations. Nutrient additions in the enclosures had a positive effect on PCB accumulation. Model results show that PCB uptake in carp can be explained from (1) uptake through invertebrate food, (2) uptake from fast-desorbing fractions in ingested sediments, and (3) uptake from water, where PCBs are in partitioning equilibrium with fast-desorbing fractions. The main implication of this research is that fast-desorbing PCB fractions in sediments have great predictive potential for bioaccumulation in benthivorous fish.
Baseline toxicity of a chlorobenzene mixture and total body residues measured and estimated with solid-phase microextraction
Leslie, H.A. ; Hermens, J.L. ; Kraak, M.H.S. - \ 2004
Environmental Toxicology and Chemistry 23 (2004)8. - ISSN 0730-7268 - p. 2017 - 2021.
hydrophobic organic-chemicals - lumbriculus-variegatus - pore-water - partition-coefficients - aquatic toxicity - fathead minnow - sediment - bioconcentration - pollutants - burdens
Body residues of compounds with a narcotic mode of action that exceed critical levels result in baseline toxicity in organisms. Previous studies have shown that internal concentrations in organisms also can be estimated by way of passive sampling. In this experiment, solid-phase microextraction (SPME) fibers were used as a too] to estimate the body residues, which were then compared to measured levels. Past application of SPME fibers in the assessment of toxicity risk of samples has focused on separate exposure of fibers and organisms, often necessitated by the amount of agitation needed in order to achieve steady state in the fibers within a convenient time period. Uptake kinetic studies have shown that in SPME fibers with thin coatings, equilibrium concentrations can be reached without agitation within the time frame of a toxicity test. In contrast to toxicity experiments to date, the SPME fibers in the current study were exposed concomitantly to the test water with the organisms, ensuring an exposure under the exact same conditions. Fibers and two aquatic invertebrate species were exposed to a mixture of four chlorobenzenes with a narcotic mode of action. The total body residue of these compounds in the organisms was determined, as was the acute toxicity resulting from the accumulation. The total body residues of both species were correlated to the total concentrations in SPME fibers. It was concluded that toxicity could be predicted based on total body residue (TBR) estimates from fiber concentrations.
Adsorption, transformation, and bioavailability of the fungicides carbendazim and iprodione in soil, alone and in combination
Leistra, M. ; Matser, A.M. - \ 2004
Journal of Environmental Science and Health. Part B, Pesticides Food Contaminants, and agricultural wastes 39 (2004)1. - ISSN 0360-1234 - p. 1 - 17.
enhanced degradation - microbial-degradation - pore-water - pesticides - vinclozolin - chemicals - sorption
When studying the effect of mixtures of toxic substances on soil organisms, attention must be paid to peculiarities in exposure to mixtures as opposed to that of single toxicants. The fungicides carbendazim and iprodione compete in the adsorption to soil. The presence of iprodione reduced the adsorption of carbendazim by 30%, while carbendazim reduced the adsorption of iprodione by 70%. Iprodione had little effect on the transformation rate of carbendazim in soil. However, carbendazim retarded the transformation of iprodione in soil by 26%. The concentration of the fungicides in pore water was found to be substantially higher for mixtures than when a fungicide alone was present in the soil. The effect of the additional fungicide on the concentration is especially apparent in the period following the first 1 to 2 weeks of the incubation. The inclusion of copper in the mixture has little additional effect on the concentration of the fungicides in pore water.