Stockholm Convention organochlorine pesticides and polycyclic aromatic hydrocarbons in Hong Kong air

Organochlorine pesticides (OCPs) including eight of the original nine pesticides listed in the Stockholm Convention on Persistent Organic Pollutants, and polycyclic aromatic hydrocarbons (PAHs) were measured in 90 air samples collected from January 2004 to March 2005, and in 304 air samples collected from January 1998 to December 2005 in Hong Kong, respectively. The annual average OCP concentrations at Tap Mun, Yuen Long and Tsuen Wan were 135+/-140 (ND-482), 186+/-183 (ND-656), and 190+/-239 fg m(-3) (ND-966), respectively, while annual (January 1998 to December 2005) average concentrations of total PAHs at Tsuen Wan, and Central/Western were 578+/-261 (117-938) and 588+/-248ngm(-3) (103-874), respectively. No seasonal and spatial variations in OCP concentrations were observed due to trace levels, and estimation of carcinogenic risks of OC pesticides was low. Naphthalene (>70%) was the dominant PAH in terms of concentrations measured. The sum of three-ring PAHs, including acenaphthene, acenaphthylene, anthracene, fluorene and phenanthrene, contributed to around 20% of the total PAH concentration while the contribution of heavier PAHs (sum of four-, five- and six-rings) was less than 5%. t-Values of the paired samples T-test for the individual PAHs showed that the concentrations of benzo(a)pyrene, the relative high cancer risk PAH, and most of the PAHs detected at Tsuen Wan and Central/Western were significantly different (p<0.01), with higher concentrations detected at Tsuen Wan. Several PAHs exhibited strong seasonality with higher concentrations in winter. Sources of PAHs were determined by investigating PAH isomer ratios which suggested petrogenic sources as primary sources of PAHs in Hong Kong air.

A comparison of disinfection by-products found in chlorinated and chloraminated drinking waters in Scotland

Seven water treatment works were selected to compare disinfection by-products (DBPs) formed when using chlorination and chloramination. DBPs measured included trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), trihalonitromethane, iodinated THMs and nitrosamines. Generally treatment works that used chloramination were able to meet the European THM regulatory limit of 100 microg L(-1) whereas the chlorinated works found it significantly more difficult. There were no significant differences in the levels of nitrogenous DBPs between the treatment works using chlorination or chloramination with the exception of the nitrosamine N-nitrosodimethylamine (NDMA) which was present at one treatment works in one season.

Aerobic biodegradation of chlorinated ethenes in a fractured bedrock aquifer: quantitative assessment by compound-specific isotope analysis (CSIA) and reactive transport modeling

A model-based analysis of concentration and isotope data was carried out to assess natural attenuation of chlorinated ethenes in an aerobic fractured bedrock aquifer. Tetrachloroethene (PCE) concentrations decreased downgradient of the source, but constant delta13C signatures indicated the absence of PCE degradation. In contrast, geochemical and isotopic data demonstrated degradation of trichloroethene (TCE) and cis-1,2-dichloroethene (DCE) under the prevailing oxic conditions. Numerical modeling was employed to simulate isotopic enrichment of chlorinated ethenes and to evaluate alternative degradation pathway scenarios. Existing field information on groundwater flow, solute transport, geochemistry, and delta13C signatures of the chlorinated ethenes was integrated via reactive transport simulations. The results provided strong evidence for the occurrence of aerobic TCE and DCE degradation. The chlorinated ethene concentrations together with stable carbon isotope data allowed us to reliably constrain the assessment of the extent of biodegradation at the site and plume simulations quantitatively linked aerobic biodegradation with isotope signatures in the field. Our investigation provides the first quantitative assessment of aerobic biodegradation of chlorinated ethenes in a fractured rock aquifer based on compound specific stable isotope measurements and reactive transport modeling.

Electrical resistivity and induced polarization tomography in identifying the plume of chlorinated hydrocarbons in sedimentary formation: a case study in Rho (Milan - Italy)

Resistivity and induced polarization surveying were originally developed for mineral exploration but are now finding new applications in the field of environmental and engineering geophysics. The present article reports the results of a geophysical survey performed with the aim of identifying a plume of chlorinated hydrocarbons in sedimentary formations of the Pandania plain. The tested site is characterized by three sand and gravel aquifers containing a quantity of clay particles which influence the overall bulk resistivity and chargeability. According to data obtained using shallow boreholes, mainly dense non-aqueous phase liquids were found as contaminants in the first and second aquifer. The aforementioned geo-electrical methods were applied in both two- and three-dimensional approaches. Steel and copper electrodes were used in the process of field data acquisition and the results of the survey were compared. The geophysical survey revealed some anomalies that could be explained by the presence of dense non-aqueous phase liquids in the soil medium. The concept of normalized chargeability facilitates the interpretation of detected induced polarization anomalies. The shape of the plume was inferred from maps of resistivity and chargeability to a depth of 25 m below the surface of the ground.

Modeling chlorine isotope trends during sequential transformation of chlorinated ethenes

There is increasing interest in combined carbon-chlorine compound-specific isotope analysis (CSIA)to differentiate between contaminant sources and to assess transformation processes. However, the significant abundance of polychlorinated molecules with several heavy chlorine isotopes complicates the evaluation of chlorine isotope trends. Therefore, the goal of this study was to develop a conceptual and mathematical framework that describes the expected chlorine isotope fractionation patterns during multistep transformation of chlorinated compounds. Reductive dechlorination of chlorinated ethenes served as an example. The study demonstrates that chlorine isotope trends can be simulated by reproducing the average behavior of light and heavy isotopes or by explicitly simulating molecules with different numbers of heavy isotopes (isotopologues). The calculations reveal that initial chlorine isotope ratios of products equal the isotope ratios of their parent compounds in the absence of secondary isotope effects, while steadily increasing during transformation. The slopes in dual isotope plots are linear for reactant and product during a one-step reaction. They become nonlinear for products that are degraded further but converge to characteristic slopes. Consideration of different scenarios reveals that combined carbon-chlorine isotope analysis bears high potential to differentiate between contaminant sources, to elucidate reaction mechanisms in laboratory studies, and to identify transformation processes in the field.

[Effect of surfactant on the volatilization of organochlorine pesticides from still artificial seawater]

The effect of sodium dodecylbenzene sulfonate (SDBS) on the volatilization of 17 organochlorine pesticides (OCPs) from still artificial seawater has been examined. The results show that SDBS at low concentration can retard the volatilization of OCPs compared to "clean" surface. The retarding influence is more pronounced for high level of SDBS than it is for low level of SDBS. A good positive correlation between the gas-seawater partition coefficients and the measured volatilization rates of OCPs is observed. Although the SDBS films present no significant, direct resistance to transfer, the films can absorb more OCPs from the above atmosphere with respect to the "clean" surface and reduce the net volatilization flux from the still artificial seawater. The effect of the film is more pronounced for volatilization of more volatile OCPs than it is for less volatile OCPs.

In vitro estrogenic and antiestrogenic potential of chlorostyrenes

Chlorostyrenes (CSs) are primarily derived from industrial by-products and are persistent and accumulative in the environment. In this study, the estrogenic and antiestrogenic activities of CSs (o-CS, m-CS, p-CS, DiCS, octa-CS) were evaluated using in vitro bioassays. o-CS and octa-CS have both estrogenic and antiestrogenic activity in the E-SCREEN assay and the ERE-reporter gene assay, indicating effects on a classical ER-mediated pathway. m-CS showed estrogenic activity in E-SCREEN but not in ERE-reporter gene assays, indicating that it may work through a non-classical ER-mediated pathway. Finally, DiCS only showed antiestrogenic activity via an ER-independent pathway, which can be induced by depletion of endogenous E(2) level by the inhibition of aromatase activity and the stimulation of E(2) metabolism. Although CSs have structural similarities to dioxins/furans, they did not have AhR agonist effects. This study is the first to show the estrogenic and antiestrogenic activity of several CSs using in vitro bioassay systems, including whether the compounds work via ER-mediated or/and non-ER-mediated pathways.

Organochlorine contaminants in fishes from coastal waters west of Amukta Pass, Aleutian Islands, Alaska, USA

Organochlorines were examined in liver and stable isotopes in muscle of fishes from the western Aleutian Islands, Alaska, in relation to islands or locations affected by military occupation. Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and rock greenling (Hexagrammos lagocephalus) were collected from nearshore waters at contemporary (decommissioned) and historical (World War II) military locations, as well as at reference locations. Total (Sigma) polychlorinated biphenyls (PCBs) dominated the suite of organochlorine groups (SigmaDDTs, Sigmachlordane cyclodienes, Sigmaother cyclodienes, and Sigmachlorinated benzenes and cyclohexanes) detected in fishes at all locations, followed by SigmaDDTs and Sigmachlordanes; dichlorodiphenyldichloroethylene (p,p'DDE) composed 52 to 66% of SigmaDDTs by species. Organochlorine concentrations were higher or similar in cod compared to halibut and lowest in greenling; they were among the highest for fishes in Arctic or near Arctic waters. Organochlorine group concentrations varied among species and locations, but SigmaPCB concentrations in all species were consistently higher at military locations than at reference locations. Moreover, all organochlorine group concentrations were higher in halibut from military locations than those from reference locations. A wide range of molecular weight organochlorines was detected at all locations, which implied regional or long-range transport and deposition, as well as local point-source contamination. Furthermore, a preponderance of higher-chlorinated PCB congeners in fishes from contemporary military islands implied recent exposure. Concentrations in all organochlorine groups increased with delta15N enrichment in fishes, and analyses of residual variation provided further evidence of different sources of SigmaPCBs and p,p'DDE among species and locations.

Effects of fish oil replacement and re-feeding on the bioaccumulation of organochlorine compounds in gilthead sea bream (Sparus aurata L.) of market size

Organochlorine pesticide residues and polychlorinated biphenyls were determined in raw materials, fish feeds and fillets from fish exposed through the productive cycle (14 months) to experimental diets with different percentages of fish oil replacement with vegetable oils. Detectable amounts of organochlorine compounds were found in raw materials derived from fish sources with none being detected in vegetable ingredients. Fish feeds presented trace concentrations of contaminants at the ng/g level, which varied according to the contribution of the different resources used in their manufacture. Contaminants did not accumulate during the first 11 months of exposure, and low concentrations of organochlorine compounds were found both at the start and at the end of this feeding period. Fillets from fish fed the fish oil diet presented the highest concentrations of organochlorine compounds, with these decreasing in proportion to fish oil replacement. Three months of fish oil re-feeding during the finishing phase only produced significant bioaccumulation over the course of the first month. By optimizing fish meal and fish oil replacement with vegetable oils alternative feeds can contribute to significantly reduce the risk of organochlorine uptake by consumers.

Assessment of the intrinsic bioremediation capacity of an eutrophic river sediment polluted by discharging chlorinated aliphatic hydrocarbons: a compound-specific isotope approach

At a field site in the industrial area of Vilvoorde, Belgium, we investigated the capacity of the indigenous microbial community of a eutrophic river sediment to biodegrade chlorinated aliphatic hydrocarbons (CAHs) originating from discharging, polluted groundwater using a compound-specific isotope approach. We specifically targeted the site's major pollutants cis-1,2-dichloroethene (cis-DCE) and vinyl chloride (VC). Analysis of Rayleigh correlation plots enabled us to assess the extent to which microbial and abiotic natural attenuation processes contributed to the mitigation of a pollution of the surface water due to discharging CAH-contaminated groundwater. Our results provide evidence for (i) the occurrence of biodegradation of cis-DCE and VC by reductive dechlorination in parts of the aquifer and at several positions in the river sediment (ii) the presence of river sediment zones exhibiting attenuation of chloroethenes by a combination of biodegradation and dilution through unpolluted water, (iii) the existence of zones in the river sediment lacking significant biodegradation, and thus (iv) a pronounced spatial heterogeneity in the occurrence and extent of biodegradation in the aquifer and river sediment. We conclude that at many investigated positions in the river sediment the indigenous microbial community failed to facilitate complete biodegradation of the groundwater-sourced chloroethenes. The overall intrinsic bioremediation capacity of the river sediment was thus not high enough to completely prevent the release of these pollutants into the surface water. These findings and conclusions are thus in agreement with those of our companion paper (1), which investigated the river sediments at the Vilvoorde study site by a combination of stable hydrogen and oxygen isotope analysis of water and the detection of chlorinated aliphatic hydrocarbons (CAHs) and their dechlorination products.

Prediction of biomagnification factors for some organochlorine compounds using linear free energy relationship parameters and artificial neural networks

Multiple linear regression and artificial neural networks (ANNs) as feature mapping techniques were used for the prediction of the biomagnification factor (BMF) of some organochlorine pollutants. As independent variables, or compound descriptors, the Abraham descriptors often employed in linear free energy relationships were used. Much better results were obtained from the nonlinear ANN model than from multiple linear regression. The average absolute error, average relative error and root mean square error in the calculation of log (BMF) by the ANN model were 0.055, 0.051 and 0.097 for the training set and 0.11, 0.086 and 0.175 for the internal validation set, respectively. The degree of importance of each descriptor was evaluated by carrying out a sensitivity analysis approach for the nonlinear model. The results obtained reveal that the order of importance is the pollutant volume, the pollutant dipolarity/polarizability and the pollutant excess molar refraction. In order to examine the credibility of the obtained ANN model the leave-many-out cross-validation test was applied which gave Q(2)= 0.827 and SPRESS = 0.15. Also the Y-scrambling procedure was applied to the ANN model in order to examine the effect of chance correlations. The results obtained reveal that it is possible to predict the BMFs of organochlorine pollutants using a nonlinear ANN model with Abraham descriptors as inputs.

Temperature-dependence of soil/air partition coefficients for selected polycyclic aromatic hydrocarbons and organochlorine pesticides over a temperature range of -30 to +30 degrees C

The soil/air partition coefficients (K(SA)) for two polycyclic aromatic carbons (PAHs) and six organochlorine pesticides (OCs) were determined by a solid-phase fugacity meter over a wide temperature range of -30 to +30 degrees C in a paddy field soil. Literature values for PAHs and OCs obtained by the same method were 1.9-5.1 times of present values at +20 degrees C. Experimentally determined K(SA) ranged over six orders of magnitude, with log K(SA) from 4.5 for alpha-hexachlorocyclohexane at +30 degrees C to 10.4 for trans-nonachlor at -20 degrees C. Separate linear regressions of log K(SA) and reciprocal absolute temperature were employed at temperatures above 0 degrees C and below 0 degrees C. The calculated enthalpies associated with the phase transfer from the soil to the air (DeltaH(SA)) over 0 to +30 degrees C range from 78 to 108 kJmol(-1), which are in a good agreement with the literature values.

Effects of manure and water applications on 1,3-dichloropropene and chloropicrin emissions in a field trial

Minimizing fumigant emissions is required for meeting air-quality standards. Application of organic materials to surface soil has been effective in reducing fumigant emissions during laboratory tests, but the potential to reduce emissions in the field has not been adequately evaluated. The objective of this study was to determine the effect of incorporated composted manure with or without water applications on fumigant emissions and the potential impact on pest control efficacy under field conditions. Treatments included a bare-soil control, composted dairy manure at 12.4 and 24.7 Mg ha(-1), postfumigation intermittent water seals (11 mm water irrigated immediately following fumigation and 4 mm at 12, 24, and 48 h), and incorporation of manure at 12.4 Mg ha(-1) combined with the water seals or a high-density polyethylene (HDPE) tarp. Telone C35 was shank-applied at 553 kg ha(-1), and emissions of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) were monitored for 10 days. The results indicate that there was no significant difference in emission peak flux and cumulative emission loss between the control and the 12.4 Mg ha(-1) manure treatment. The higher manure rate (24.7 Mg ha(-1)) resulted in lower emission flux and cumulative emission loss than 12.4 Mg ha(-1), although the differences were only significant for CP. In contrast, the water treatments with or without manure incorporation significantly reduced peak emission rates (80% reduction) and cumulative emission loss ( approximately 50% reduction). The manure + HDPE treatment resulted in the lowest CP emissions but slightly higher 1,3-D emissions than the water treatments. Reductions in peak emission from water treatments can be important in reducing the potential acute exposure risks to workers and bystanders. This research demonstrated that incorporation of composted manure alone did not reduce fumigant emissions and effective emission reduction with manure amendment may require higher application rates and/or more effective materials than those used in this study.

Assessment of oral bioaccessibility of organochlorine pesticides in soil using an in vitro gastrointestinal model

A static in vitro gastrointestinal model was used to investigate the oral bioaccessibility of organochlorine pesticides (OCPs) including hexachlorocyclohexane isomers (HCHs) and dichlorodiphenyltrichloroethane and metabolites in contaminated soils with different organic matter contents. A key hypothesis tested was that a fraction of the mobilized contaminants is sorbed on the solid after digestion, and this fraction could be desorbed and become bioaccessible in the intestinal tract due to absorption of the dissolved fraction by the small intestine. The bioaccessibility would be underestimated if the sorbed fraction was separated from the fluid by centrifugation or filtration in an in vitro test. In our experiment, a procedure using multiple fluid-to-solid ratios was developed to characterize the sorption. It was found that 8-38% of the mobilized OCPs were sorbed on the residue and remained in the solid phase after the separation. Taking into consideration the sorbed fraction, the measured bioaccessibilities of the OCPs varied from 4% to 97% depending on the properties of the soils and the compounds. The enantiomeric ratios of chiral compounds studied were also determined to distinguish biotic (enzymatic) and abiotic (chemical extraction) processes in the in vitro digestion model. It was found that although alpha-HCH in the raw soils was racemic, (+)-alpha-HCH was enriched in the gastric digestive fluid but depleted in the intestinal digestive fluid.

Reduction of polychlorinated ethanes and carbon tetrachloride by structural Fe(II) in smectites

Ferrous iron associated with clay minerals can be important for the reductive transformation of organic contaminants in anoxic soils and groundwaters. We investigated the reactivity of structural Fe(II) in ferruginous smectite for the reduction of a series of polychlorinated alkanes (hexa-, penta-, 1,1,1,2-and 1,1,2,2-tetrachloroethane, and carbon tetrachloride (CCl4)) in laboratory batch reactors. Evaluation of reaction kinetics, product distribution, and C-isotope fractionation suggest that polychlorinated ethanes containing three alpha-Cl atoms reacted via reductive beta-elimination to the corresponding ethenes while CCl4-reduction leads predominantly to the formation of chloroform. Reduction kinetics followed a typical biphasic behavior characteristic of the presence of two types of Fe(II) species exhibiting different reactivity in the octahedral sheet of smectites, and reaction rate constants were pH-independent. Dehydrochlorination reactions of chloroethanes containing at least one beta-H atom were found to compete with or even dominate over the reduction reaction with increasing suspension pH. Reference experiments in homogeneous solution and with non-reduced smectite performed in the pH range of 5.5-8.5 suggest that the HCl-elimination is not catalyzed at mineral surfaces. From the observed slow transformation of chloroalkanes, we hypothesize that structural Fe(II) in smectites will be important mainly as a reductant in the subsurface once iron(hydr)oxides have been reductively dissolved.

Solvent and temperature effects on the conformational equilibria of a dihydrobenzo[h]quinolinium fluoroborate

Spectra of the N-phenyl-5,6-dihydro-2,4-diphenylbenzo[h]quinolinium tetrafluoroborate (1) and of the N-phenyl-5,6,8,9-tetrahydro-7-phenyldibenzo[c,h]acridinium tetrafluoroborate (2) were recorded in various solvents and temperatures. The analysis of the (1)H-NMR spectra of the tetrafluoroborate salt 1, recorded in acetone, acetonitrile, 1,1,2,2-tetrachloroethane and chloroform, revealed the existence of an equilibrium between two conformers in solution. Tight ion-pairing in chloroform led to a smaller barrier for interconversion between the two conformers. In more polar solvents, where the dihydrobenzoquinolinium exists as a free cation, theoretical calculations predicted larger barriers. The spectra of 1 in 1,1,2,2-tetrachloroethane also varied with temperature, resembling at higher temperatures the spectrum in CDCl(3) and at 300K spectra in more polar media. Spectra of 2 did not vary with the solvent or the temperature, in an indication of a much higher barrier to conformational interconversion, because of a greater steric hindrance between the N-phenyl substituent and the dihydrobenzo rings.

Enantiomeric signatures of chiral organochlorine pesticides in consumer fish from South China

Despite the importance of chiral organochlorine pesticide enantiomers in terms of environmental effects, no relevant data have been acquired in consumer fish. The present study determined the residual levels and enantiomer fractions (EFs) of α-HCH, o,p'-DDT, and o,p'-DDD in 11 consumer fish species from South China, including 6 freshwater farmed fish, 3 seawater farmed fish, and 2 wild marine fish. The mean concentrations of α-HCH, o,p'-DDT, and o,p'-DDD were 0.27, 4.4, and 3.5 ng/g wet, respectively, in all fish samples measured (n = 125). The EFs of α-HCH varied widely, from below the racemic EF of 0.5 to above it. For o,p'-DDT, the (+)-enantiomer dominated in all fish species. On the other hand, all EFs of o,p'-DDD, a metabolite of o,p'-DDT, were below 0.5, suggesting the (-)-enantiomer was preferentially enriched in fish. In addition, all three target analytes showed species dependence of EFs, consistent with results from other previous studies. Moreover, no significant correlations were found between the EFs and concentrations of α-HCH, o,p'-DDT, and o,p'-DDD in red drum, snubnose pompano, and crimson snapper, with the exception of o,p'-DDD in snubnose pompano, in which weak correlations were detected. Nevertheless, more studies are needed to explore the residual levels and toxicity of chiral contaminants in consumer fish or other foodstuff to further develop the human risk assessment framework based on chiral signatures.

Multiresidue analysis of organochlorine and pyrethroid pesticides in ground beef meat by gas chromatography-mass spectrometry

A multiresidue method was developed and optimized for the identification/quantification of organochlorine pesticides (OCPs) and pyrethroids (PYRs) in beef meat samples. Samples extraction was performed by an automated solvent extractor and the extracts were cleaned-up by a tandem-cartridge system consisting of an Extrelut NT3 combined with a Sep-Pack C18 cartridge and a florisil minicartridge. Analysis was finally carried out by gas chromatography coupled with quadrupole mass spectrometry (GC/MS). The performance of the method was investigated in terms of linearity, accuracy, precision, detection limit (LOD) and quantification limit (LOQ). Good linearity was obtained, with correlation coefficients (r(2)) higher than 0.98. Mean recoveries were found in the ranges 70-110 % and 84-99 % for the investigated OCPs and PYRs, respectively, with the exception of extremely volatile hexachlorobenzene (HCB). RSD% turned out to range from 2 to 15 %. LOQ values were in the range 0.005-0.1 mg/kg for either class of compounds. The method developed was successfully tested on 50 commercial beef meat samples from the market area of Rome (Italy), proving to be a useful tool in routine multiresidue analysis of OCPs and PYRs for monitoring purposes. None of the compounds of interest were observed above their respective LOQ.

Factors influencing trends of polychlorinated naphthalenes and other dioxin-like compounds in lake trout (Salvelinus namaycush) from Lake Ontario, North America (1979-2004)

Concentrations of polychlorinated naphthalenes (PCNs) were determined in archived lake trout (Salvelinus namaycush) from Lake Ontario, North America, collected between 1979 and 2004 to evaluate their temporal trends and the factors influencing their trends. Concentrations of PCNs, as well as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and non- and mono-ortho-substituted polychlorinated biphenyls (DL-PCBs), which were measured for comparative purposes, declined by eight-, seven-, and fivefold, respectively, between 1979 and 2004. Apparent elimination rate constants (k2) were calculated as the slopes of the regression lines of concentration versus time for PCN, DL-PCB, and PCDD/F congeners to compare the rate of decrease among congeners within and between compound classes. The k2 values for PCNs that had two pairs or three adjacent carbons unsubstituted with chlorine (congeners that can be biotransformed by vertebrates) were not significantly different from zero, indicating no decline in fish. For PCN congeners having no adjacent carbons unsubstituted with chlorine, the k2 values generally increased with hydrophobicity and degree of chlorination. This pattern differed from that of PCDD/Fs and DL-PCBs and from previous findings for non-DL-PCBs, for which the rate of contaminant decline decreased with hydrophobicity, and the pattern also differed from expectations based on thermodynamics. Differences in the rate of decline of PCN congeners may be caused by changes in source or mixture formulations over time and/or metabolic dechlorination of the less stable, higher-chlorinated PCNs 73, 74, and 75 to lower-chlorinated congeners. Based on suggested dioxin toxic equivalency factors, PCN concentrations in these whole lake trout may be sufficient to trigger consumption restrictions in Ontario, Canada, and our results suggest that PCNs merit incorporation into monitoring and assessment programs.

Hydrodechlorination of DDT and chloroalkanes over carbon-supported Ni-Mo catalyst

Catalytic hydrodechlorination (HDC) is an efficient method for the elimination of chlorinated compounds from organic wastes. HDC allows for the recovery of parent hydrocarbons. Herein, we studied the dechlorination of chlorododecane (CDD), dichlorocyclohexane (DCH) and dichlorodiphenyltrichloroethane (DDT) over a sulfided Ni-Mo/C catalyst in a flow reactor. The Ni-Mo/C catalyst was prepared by the incipient wetness method using a granular activated carbon support. In contrast to alumina, which is a commonly used support for commercial catalysts, the carbon support is resistant to decomposition by HCl formed during the HDC reaction. The composition of the tested catalyst was 5 wt.% NiO and 15 wt.% MoO(3), and it was characterized by well developed both the micro- and mesoporosity (V(mic)=0.559 cm(3)g(-1), V(mes)=0.430 cm(3)g(-1)). The level of conversion of CDD, DCH, and DDT was directly related to reaction temperatures in the HDC process; the total chlorine removal was achieved at 200 degrees C. The tested catalyst was determined to have good thermal stability in the HDC process at 170 degrees C for 100 h. This corresponded to conversions of 85-72% for CDD and 81-79% for DCH. For CDD the hydrogen pressure affected the ratio of dodecane to dodecene in the reaction products.

Enantiomeric signatures of organochlorine pesticides in Asian, trans-Pacific, and western U.S. air masses

The enantiomeric signatures of organochlorine pesticides were measured in air masses from Okinawa, Japan and three remote locations in the Pacific Northwestern United States: Cheeka Peak Observatory (CPO), a marine boundary layer site on the Olympic Peninsula of Washington at 500 m above sea level (m.a.s.l); Mary's Peak Observatory (MPO), a site at 1250 m.a.s.l in Oregon's Coast range; and Mt. Bachelor Observatory (MBO), a site at 2763 m.a.s.l in Oregon's Cascade range. The enantiomeric signatures of composite soil samples, collected from China, South Korea, and the western U.S. were also measured. The data from chiral analysis was expressed asthe enantiomeric fraction, defined as (+) enantiomer/(sum of the (+) and (-) enantiomers), where a racemic composition has EF = 0.5. Racemic alpha-hexachlorocyclohexane (alpha-HCH) was measured in Asian air masses at Okinawa and in Chinese and South Korean soils. Nonracemic alpha-HCH (EF = 0.528 +/- 0.0048) was measured in regional air masses at CPO, and may reflect volatilization from the Pacific Ocean and regional soils. However, during trans-Pacific transport events at CPO, the alpha-HCH EFs were significantly more racemic (EF = 0.513 +/- 0.0003, p < 0.001). Racemic alpha-HCH was consistently measured at MPO and MBO in trans-Pacific air masses that had spent considerable time in the free troposphere. The alpha-HCH EFs in CPO, MPO, and MBO air masses were negatively correlated (p = 0.0017) with the amount of time the air mass spent above the boundary layer, along the 10-day back air mass trajectory, prior to being sampled. This suggests that, on the West coast of the U.S., the alpha-HCH in the free troposphere is racemic. Racemic signatures of cis- and trans-chlordane were measured in air masses at all four air sampling sites, suggesting that Asian and U.S. urban areas continue to be sources of chlordane that has not yet been biotransformed.

Sonochemical degradation of chlorinated organic compounds, phenolic compounds and organic dyes - a review

Sonochemical processes have been widely used in chemistry and chemical engineering field. Recently, these processes have found new applications in the environmental field, because of advantages in terms of operational simplicity, secondary pollutant formation and safety. Several studies have reported on sonochemical degradation of organic compounds that are toxic in nature. The objective of this review was to identify and examine some of the studies on sonochemical degradation of chlorinated organic compounds, phenolic compounds and organic dyes. This review also examines the basic theory of sonochemical reactions and the use of sonochemical reactors for environmental applications.

Accumulation and mother-to-calf transfer of anthropogenic and natural organohalogens in killer whales (Orcinus orca) stranded on the Pacific coast of Japan

Blubber samples were analyzed for anthropogenic and natural persistent organohalogens in nine killer whales (Orcinus orca) stranded on the northern coast of Japan in 2005. Anthropogenic organohalogens were dominated by DDTs (40-240 microg/g lipid weight (lw)), PCBs (19-68 microg/g lw), and chlordanes (trans-nonachlor, 15-80 microg/g lw). Polybrominated diphenyl ethers (PBDEs) were detected at a range of 0.22-0.64 microg/g lw (BDE-47, 42-74% of SigmaPBDE). For natural organohalogens, mixed halogenated dimethylbipyrroles (Br4Cl2-DBP, 6.4-26 microg/g lw), heptachlorinated methylbipyrrole (Cl7-MBP, 0.5-1.9 microg/g lw), two methoxylated tetrabromodiphenyl ethers (6-MeO-BDE47, 0.11-0.58 microg/g lw; 2'-MeO-BDE68, 0.02-0.06 microg/g lw), and dimethoxylated tetrabromobiphenyl (2,2'-diMeO-BB80, 0.06-0.20 microg/g lw) were present. These concentrations in the blubber were higher in calves than in lactating females, indicating that large quantities of the persistent organohalogens transferred from the mother to the calf through lactation. The mother-to-calf transfer ratios of PCBs and PBDEs were significantly decreased with increasing number of halogen substituents, suggesting that higher halogenated congeners are less transferable.

Direct toxicity assessment of volatile chlorinated hydrocarbon-contaminated groundwater and derivation of a site-specific guideline

Groundwater contaminated with a mixture of 14 volatile chlorinated hydrocarbons (VCHs) discharges to an estuarine embayment in Sydney, Australia. A screening-level hazard assessment identified a potential risk to aquatic organisms from surface water contaminated by the groundwater. Direct toxicity assessment of the groundwater was undertaken on 5 indigenous marine species to assess toxicity and derive a site-specific guideline. The testing included acute tests, subchronic tests on early life stages, and a chronic test. Test organisms included a microalga (Nitzschia closterium), an amphipod (Allorchestes compressa), a polychaete worm (Diopatra dentata), and sea urchin (Heliocidaris tuberculata) and oyster larvae (Saccostrea commercialis). Toxicity testing was undertaken in sealed containers to prevent loss of VCHs, and concentrations of VCHs were measured to accurately assess exposure concentrations. No observed effect concentration (NOEC) values varied from 1.56% dilution (1.11 mg total VCHs) to 50% dilution (45.5 mg total VCHs). EC50 values varied from 4.8% dilution (3.77 mg total VCHs) to more than 50% dilution (45.5 mg total VCHs). NOEC data were used to derive species sensitivity distributions (SSDs) and a site-specific guideline. SSDs were derived from Burr type III (including the Pareto) and log-normal distributions. The log-normal distribution represented the best fit, and because the Pareto distribution is a finite threshold model more suited to toxicants with a threshold mode of action, the log-normal SSD and the associated 95% trigger value (TV) of 830 microg/L of total VCHs, was adopted as the site-specific TV for the groundwater.

A new procedure for the treatment of organochlorinated off-gases combining adsorption and catalytic hydrodechlorination

A new process for the treatment of off-gases containing chlorinated pollutants is presented in this paper. The proposed process consists of the adsorption of the chlorinated compound, followed by the regeneration of the spent adsorbent using hydrogen. Therefore, this process gathers the advantages of the conventional adsorption (useful for a wide range of emissions, even those air-diluted) and the catalytic hydrodechlorination (complete destruction of the chlorinated compound, ensuring the absence of oxidized byproduct). Since it is widely accepted that palladium is the most active phase for catalytic hydrodechlorination, this metal was supported on a given adsorbent. Different materials were tested in this work for use as adsorbents in this application (NaX, KL and ZSM-5 zeolites; activated carbons and synthetic clays), using trichloroethene as model compound. Based on their adsorption capacities, measured by temperature-programmed desorption (TPD), KL and NaX zeolites (adsorption capacity of 25 and 30 micromol/g, respectively), as well as an activated carbon (30 micromol/ g), have been selected for preparing the Pd-containing adsorbents (0.5 wt% of Pd). The most selective catalyst for the total hydrodechlorination of the adsorbed chlorinated compound was the KL supported zeolite, showing full selectivity (at a 92% conversion) for total hydrodechlorination in the hydrogen treatment of the saturated material.