Measuring nonpolar organic contaminant partitioning in three Norwegian sediments using polyethylene passive samplers
ABSTRACT Freely dissolved pore water concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), penta- and hexachlorobenzene (PeCB and HCB), octachlorostyrene (OCS), p,p'-DDE and p,p'-DDD were measured in bottom sediments from three sites in Norway. Sediments were from Aker Brygge, site of a former shipyard in the inner part of Oslofjord, Frierfjord in the Grenlandsfjord area, impacted during the 50 year-long activity of a magnesium smelter plant, and from Kristiansand harbour, site with high industrial activity. Low density polyethylene (LDPE) membrane samplers were exposed to these sediments in laboratory incubation under constant and low-level agitation for periods of 1, 2, 6, 13, 23 and 50 days. Freely dissolved pore water concentrations were estimated from contaminant masses accumulated and sampling rates obtained from the measurement of kinetics of dissipation of performance reference compounds (PRCs). Marked differences in freely dissolved PAH concentrations and resulting organic carbon-normalised sediment-pore water partition coefficients, logK(TOC), between these three sediments could be observed despite the generally similar total sediment concentrations. In contrast with the PAH data, partitioning of PCBs and other organochlorine compounds (OCs) was relatively similar in all three sediments. For sediments from Frierfjord and Kristiansand, logK(TOC) values were lower for PCBs/OCs than for PAHs, indicating higher availability. Similar partitioning of PAHs and PCBs/OCs was found for sediments from Aker Brygge. No simple logK(oc)-logK(ow) relationships could model these data successfully. These results support the notion that the assessment of the risk posed by these compounds present in sediments in most cases requires actual measurement of contaminant availability.
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- "Air streaming can extend PAHs to large distances and subsequently return them to the soil through precipitation. In the soil, we find them bound to bigger particles, from where some evaporate in the air, while others penetrate into deeper layers contaminating underground water (5). The general population is exposed to PAHs from the environment through small-sized respirable particles, water and food, as well as from the occupational environment (6). "
ABSTRACT: Polycyclic aromatic hydrocarbons (PAHs) are among the most prevalent environmental pollutants and result from the incomplete combustion of hydrocarbons (coal and gasoline, fossil fuel combustion, byproducts of industrial processing, natural emission, cigarette smoking, etc.). The first phase of xenobiotic biotransformation in the PAH metabolism includes activities of cytochrome P450 from the CYP1 family and microsomal epoxide hydrolase. The products of this biotransformation are reactive oxygen species that are transformed in the second phase through the formation of conjugates with glutathione, glucuronate or sulphates. PAH exposure may lead to PAH-DNA adduct formation or induce an inflammatory atherosclerotic plaque phenotype. Several genetic polymorphisms of genes encoded for enzymes involved in PAH biotransformation have been proven to lead to the development of diseases. Enzyme CYP P450 1A1, which is encoded by the CYP1A1 gene, is vital in the monooxygenation of lipofilic substrates, while GSTM1 and GSTT1 are the most abundant isophorms that conjugate and neutralize oxygen products. Some single nucleotide polymorphisms of the CYP1A1 gene as well as the deletion polymorphisms of GSTT1 and GSTM1 may alter the final specific cellular inflammatory respond. Occupational exposure or conditions from the living environment can contribute to the production of PAH metabolites with adverse effects on human health. The aim of this study was to obtain data on biotransformation and atherosclerosis, as well as data on the gene polymorphisms involved in biotransformation, in order to better study gene expression and further elucidate the interaction between genes and the environment.Biochemia Medica 10/2013; 23(3):255-65. DOI:10.11613/BM.2013.032 · 2.40 Impact Factor
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- "The mechanistic concept of bioaccessibility involves binding , release, transport, uptake through a membrane, and incorporation into a living system. Of particular importance among these process is desorption (Allan et al. 2012; Megharaj et al. 2011). Conceptually, an empirical model is most commonly used to quantify the triphasic nature of PAH desorption, which assumes that desorption occurs from three compartments in the soil defined by fast, slow and very slow rates, each following first-order kinetics (Liu et al. 2011; Yang et al. 2010). "
ABSTRACT: The effectiveness of many bioremediation systems for PAH-contaminated soil may be constrained by low contaminant bioaccessibility due to limited aqueous solubility or large sorption capacity. Information on the extent to which PAHs can be readily biodegraded is of vital importance in the decision whether or not to remediate a contaminated soil. In the present study the rate-limiting factors in methyl-β-cyclodextrin (MCD)-enhanced bioremediation of PAH-contaminated soil were evaluated. MCD amendment at 10 % (w/w) combined with inoculation with the PAH-degrading bacterium Paracoccus sp. strain HPD-2 produced maximum removal of total PAHs of up to 35 %. The desorption of PAHs from contaminated soil was determined before and after 32 weeks of bioremediation. 10 % (w/w) MCD amendment (M2) increased the Tenax extraction of total PAHs from 12 to 30 % and promoted degradation by up to 26 % compared to 6 % in the control. However, the percentage of Tenax extraction for total PAHs was much larger than that of degradation. Thus, in the control and M2 treatment it is likely that during the initial phase the bioaccessibility of PAHs is high and biodegradation rates may be limited by microbial processes. On the other hand, when the soil was inoculated with the PAH-degrading bacterium (CKB and MB2), the slowly and very slowly desorbing fractions (F sl and F vl ) became larger and the rate constants of slow and very slow desorption (k sl and k vl ) became extremely small after bioremediation, suggesting that desorption is likely rate limiting during the second, slow phase of biotransformation. These results have practical implications for site risk assessment and cleanup strategies.Biodegradation 09/2012; 24(3). DOI:10.1007/s10532-012-9593-2 · 2.49 Impact Factor
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ABSTRACT: Many contaminants are recalcitrant against degradation. Therefore, when primary sources have been discontinued, contaminated sediments often function as important secondary pollution sources. Since the management and potential remediation of contaminated marine sediments may be very costly, it is important that the environmental risks of contaminants present in these sediments and benefits of remediation are evaluated as accurately as possible. The objective of this study was to evaluate the bioavailability of common organochlorine contaminants and polycyclic aromatic hydrocarbons (PAHs) in selected polluted sediments from Norway by simple generic sorption models (free energy relationships), as well as by pore water concentration measurements. Furthermore, the aim was to predict bioaccumulation from these bioavailability estimates for comparison with in vivo bioaccumulation assessments using ragworm (Nereis virens) and netted dogwhelk (Hinia reticulata). Predicted biota-to-sediment accumulation factors (BSAFs) derived from pore water concentration estimates were in better agreement with the bioaccumulation observed in the test organisms, than the generic BSAFs expected based on linear sorption models. The results therefore support that site-specific evaluations of bioaccumulation provide useful information for more accurate risk assessments. A need for increased knowledge of the specific characteristics of benthic organisms, which may influence the exposure, uptake and elimination of contaminants, is however emphasized.Science of The Total Environment 11/2012; 442C:336-343. DOI:10.1016/j.scitotenv.2012.10.060 · 4.10 Impact Factor