Compounds structurally related to Dechlorane Plus in sediment and biota from Lake Ontario (Canada)

The historical occurrence of Dechlorane Plus (DP) and detection of novel compounds structurally related to DP is described in a dated Lake Ontario sediment core. Our core was collected near the mouth of the Niagara River, which is known to be a major source of DP to the lake. Maximum DP concentrations (920 ng g(-1), dry weight) were observed between 1976 and 1980, the highest reported to date. Following that time, we observed a dramatic decrease in DP concentration which coincided with the enactment of United States federal and state laws to mitigate free release of chemicals into the Niagara River and installation of an industrial wastewater treatment facility. During the course of our research, four new substances structurally related to DP were also identified. These compounds were thought to arise from the Diels-Alder reactions resulting from impurities present in 1,5-cyclooctadiene, a feedstock used in production of DP. To confirm our hypothesis, Diels-Alder reactions were performed on the individual impurities. Using different stationary-phase capillary gas chromatography columns and high-resolution mass spectrometry, we were able to positively identify some of these novel compounds in the core. Interestingly, we also were able to identify a monoadduct compound, formed by addition of 1 mol of hexachlorocyclopentadiene to 2 mol of 1,3-cyclooctadiene, in lake trout. The concentration of this monoadduct was approximately 2 orders of magnitude greater than that of DP, suggesting that it is more bioaccumulative.

Isomer-specific bioaccumulation and trophic transfer of Dechlorane Plus in the freshwater food web from a highly contaminated site, South China

Dechlorane Plus (DP), a highly chlorinated flame retardant, has been detected in water, sediment, and aquatic organisms in a reservoir in the vicinity of electronic waste recycling workshops in South China. The biomagnification potential of DP in the food web was assessed and compared with that of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs). DP was detected in all of the aquatic species, with concentrations of 19.1-9630 ng/g lipid wt. A depletion of anti-DP was observed in organisms compared with abiotic samples and the fraction of anti-DP was found to be further decreased upon moving up the trophic levels. This result suggested a stereospecific metabolism of anti-DP and/or isomer-selective uptake of syn-DP was occurring in organisms. Both syn- and anti-DP were significantly biomagnified in the present food web, with trophic magnification factors (TMFs) of 11.3 and 6.6, respectively. The trophic magnification potentials of the DP isomers were generally comparable to or lower than those of the highly recalcitrant PCB congeners in the same food web, but were 2-3 times greater than those of PBDE congeners.

Organochlorine pesticide and heavy metal residues in some edible biota collected from Quanzhou Bay and Xinghua Bay, southeast China

In order to assess the contamination of edible marine organisms in Quanzhou and Xinghua Bays, Fujian Province, China, concentrations of organochlorine pesticides (hexachlorocyclohexane isomers or HCHs and dichlorodiphenyltrichloroethane isomers/derivatives or DDTs) and heavy metals (Cu, Pb, Zn, As, Cr, Cd, Ni and Hg) in 13 species collected from different sites in the bays were analyzed by GC-ECD and ICP-MS. The concentration of the sum of DDTs exceeded that the sum of HCHs in the samples. Most of the organisms showed higher levels of DDTs than the first level criterion (10 ng/g) for marine biological quality in China (GB 18421-2001) but conformed to the first level criterion (20 ng/g) for HCHs. The estimated mean daily uptake of pesticides was below the level for minimal risk to the consumers. The levels of Cd, As and Pb in most organisms from both bays were markedly elevated and above the recommended legal limits for human consumption. Our results showed the need for routine monitoring of marine species contamination to ensure public and environmental health.

Influence of nanoscale zero-valent iron on geochemical properties of groundwater and vinyl chloride degradation: A field case study

A 200m(2) pilot-scale field test successfully demonstrated the use of nanoscale zero-valent iron (NZVI) for effective remediation of groundwater contaminated with chlorinated organic compounds in Taiwan within six months. Both commercially available and on-site synthesized NZVI were used. A well-defined monitoring program allowing to collect three-dimensional spatial data from 13 nested multi-level monitoring wells was conducted to monitor geochemical parameters in groundwater. The degradation efficiency of vinyl chloride (VC) determined at most of monitoring wells was 50-99%. It was found that the injection of NZVI caused a significant change in total iron, total solid (TS) and suspended solid (SS) concentrations in groundwater. Total iron concentration showed a moderate and weak correlation with SS and TS, respectively, suggesting that SS may be used to indicate the NZVI distribution in groundwater. A decrease in oxidation-reduction potential (ORP) values from about -100 to -400mV after NZVI injection was observed. This revealed that NZVI is an effective means of achieving highly reducing conditions in the subsurface environment. Both VC degradation efficiency and ORP showed a correlative tendency as an increase in VC degradation efficiency corresponded to a decrease of ORP. This is in agreement with the previous studies suggesting that ORP can serve as an indicator for the NZVI reactivity.

Analysis of the residues of 20 organochlorine pesticides in Herba epimedii, a Chinese herbal medicine, by solid-phase extraction with gas chromatography/negative chemical ionization-mass spectrometry

A multiresidue analytical method has been developed to simultaneously determine the residues of 20 organochlorine pesticides in Herba epimedii, a traditional Chinese medicine. The 20 pesticides are included in the list of regulated substances by the Food and Environmental Hygiene Department in Hong Kong. The method consists of solid-phase extraction for cleanup of samples and GC coupled on-line with negative chemical ion-MS to analyze the target pesticides. The chromatographic separation of the compounds was carried out on a DB-1701 column by using an optimal temperature program, and the quantitative analysis was conducted by selected ion monitoring. The LOD and LOQ values fell in the range of 0.0555-5.8821 and 0.1241-17.9333 ng/g, respectively. The average recoveries were between 75.4 and 90.7% (n=5) for the 20 organochlorine pesticides. The developed method proved to be reliable and accurate, and permits rapid determination of the 20 organochlorine pesticides in one run.

Organochlorine compounds and polycyclic aromatic hydrocarbons in surface sediment from Baiyangdian Lake, North China: concentrations, sources profiles and potential risk

Organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons (PAHs) were determined in nineteen surface sediment samples collected from Baiyangdian Lake and its inflowing river (Fuhe River) in North China. Total concentrations of OCPs, PCBs and PAHs in sediments ranged from 5.4 to 707.6 ng/g, 2.3 to 197.8 ng/g, and 101.3 to 6360.5 ng/g, respectively. The levels of contaminants in Fuhe River were significantly higher than those in Baiyandian Lake. For hexachlorocyclohexane (HCHs) and dichlorodiphenytrichloroethanes (DDTs), alpha-HCH and p,p'-DDT were predominant isomers; while for PCBs, PCB 28/31, PCB 40/103, PCB 60, PCB 101, and PCB 118 were predominant congeners. Possible sources derived from historical usage for OCPs and incomplete combustion fuel, wood, and coal and exhaustion of boats or cars for PAHs. Risk assessment of sediment indicated that sediments in Fuhe River were likely to pose potential biological adverse impact.

Enantioselective induction of oxidative stress by acetofenate in rat PC12 cells

In a non-chiral environment, the enantiomers of a racemate possessed the identical physico-chemical properties, but in the biological systems they possessed different activities. Considering that the involvement of oxidative damage has been implicated in the toxicities of various pesticides, this study investigated the possibility of enantioselective oxidative stress and cytotoxicity induction by acetofenate (AF) which contains an asymmetrical center on PC12 cells. The results of the cytotoxicity assay indicated that S-(+)-AF presented more toxic effects than R-(-)-AF and (+)-AF. It also demonstrated that S-(+)-AF possessed the strongest effects in induction of reactive oxygen species (ROS) production, decrease in superoxide dismutase (SOD) and catalase (CAT) activities, and increase in malondialdehyde (MDA) level. These results suggested that AF and its enantiomers could induce enantioselective cytotoxicity in PC12 cells mediated by oxidative stress. Therefore, the assessment in environmental safety and new chiral pesticide development should consider enantioselectivity.

Spatial and seasonal variations of organochlorine compounds in air on an urban-rural transect across Tianjin, China

The spatial and seasonal variations of atmospheric organochlorine compounds (OCs) concentrations was investigated at six sites on an urban-rural transect in Tianjin, China from July 2006 to June 2008 using XAD-based passive air samplers. The samplers were deployed for six time periods. Hexachlorocyclohexanes (HCHs) air concentrations were highest at Tanggu and Tuanbowa and decreased dramatically further away from these two sites. The maximum proportion of beta-HCH compared to SigmaHCHs (12.1-32.2%) was found in Hangu, suggesting its persistence. The alpha/gamma-HCH ratio was between 1.26 and 5.79 which signified the combined influence of technical HCHs and lindane. Dichlorodiphenyltrichloroethane related compounds (DDTs) were higher at Hangu compared with other sites which was attributed to its continuing production there. Low p,p'-DDE/p,p'-DDT in Hangu and Tanggu were found, reflecting the fresh input of DDTs while the relatively high o,p'-DDT/p,p'-DDT ratios indicated the agricultural application of dicofol. Polychlorinated biphenyls distribution elucidated that the urban area could be their emission source. Hexachlorobenzene, with the highest concentrations in Tanggu, showed the smallest industrial/urban-rural gradient ( approximately 4-9 times) than those of other chemicals (approximately 17-49 for SigmaHCHs, approximately 10-77 for SigmaDDTs), but comparable with PCBs (PCB28 and PCB52) (approximately 3-10). Seasonal variations of OCPs were featured by higher concentration in spring and summer and lower in winter. This was likely associated with (i) their temperature-driven re-volatilization and (ii) application of dicofol in late spring and summer and DDT-containing antifouling paints for fishing ships in summer. However seasonality of PCBs concentrations was site-specific on the Tianjin scale.

Behavior of polychlorinated benzenes, PCDD/Fs and dioxin-like PCBs during incineration of solid waste contaminated with mg/kg levels of hexachlorobenzene

Hexachlorobenzene (HCB), one of the well-known Persistent Organic Pollutants (POPs), is present in some pigments and these raw materials with maximum level of several thousand of mg/kg. Considering that these pigments have been used in long-life products, such as car parts, construction materials and electrical and electronic equipments, the articles containing HCB at a concentration of several hundred mg/kg still have to undergo waste management. In this study, we performed a combustion experiment involving solid waste containing 300 mg/kg of HCB as the input material using a pilot-scale incinerator to determine the destruction of HCB and its influence on the behavior of other polychlorinated benzenes (CBzs) and unintentionally produced POPs, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs). HCB at a concentration of 300 mg/kg in the input material was destroyed mainly in the primary combustion zone. Overall the destruction efficiency of HCB was > 99.9985%. The input concentration of HCB did not significantly affect the formation and destruction or the final emissions of other CBzs, PCDD/Fs and dl-PCBs. These results indicate that incineration, when operated and structured to minimize emissions of dioxin-related compounds, is considered to be one of the Best Available Technologies for the appropriate treatment of waste containing HCB with a concentration in the order of mg/kg.

Electrochemical oxidation of landfill leachates at pilot scale: evaluation of energy needs

Two of the main drawbacks to be overcome before full scale implementation of boron-doped diamond electro-oxidation were addressed in this work; its energy consumption and hazard of formation of chlorinated organics. This was framed within a study in which the technical and economic feasibility of BDD electro-oxidation of landfill leachate was evaluated at pilot scale. On one hand, its technical feasibility was assessed based on COD and NH(4)(+) removal, allowing the selection of the operation conditions that provide optimal energy efficiency, and special attention was paid to the risk of formation of undesired by-products such as nitrite, nitrate ions and trihalomethanes. On the other hand, treatment costs were estimated based on energy consumption required to reach the disposal limits to natural watercourses established by legislation. The results were compared with those of other commonly used AOPs. Under the operating conditions studied, the concentration of COD decreased below the disposal limit (160 mg L(-1)) and ammonia concentration reached values as low as 30 mg L(-1). The energy consumption needed was estimated at 54 kWh/m(3) and the formation of chlorination by-products appeared to be low as the maximum total trihalomethane concentration detected was 432 microg/L.

Anaerobic biodegradation of organochlorine pesticides in contaminated soil - significance of temperature and availability

Anaerobic biodegradation of the pesticides: gamma-hexachlorocyclohexane, methoxychlor, o,p'- and p,p'-DDT in field polluted soil was tested at 12, 22 and 30 degrees C, using methanogenic granular sludge as inoculum. The contaminants were removed quite effectively at all temperatures and their removal rates increased 1.2-1.7 times with the increase in temperature. In most cases pesticide concentrations after an initial substantial decline remained almost constant until the end of experiment. These residual concentrations were also temperature dependent and they were 1.4-8.2 times higher at 12 degrees C than at 30 degrees C. DDT was degraded via DDD and accumulation of this metabolite was lower (19-64%) than the corresponding amount of removed DDT, especially at higher temperatures. Further transformation of DDD was confirmed by formation of p,p'-dichlorobenzophenone. Additional experiment demonstrated that removal was limited to readily desorbing fractions of pesticides, while their desorption-resistant fractions persisted in the soil. However, DDD metabolite was only partially removed despite its good desorbability.

Bioremediation of chlorinated pesticide-contaminated soil using anaerobic sludges and surfactant addition

Methanogenic granular sludge and wastewater fermented sludge were used as inocula for batch tests of anaerobic bioremediation of chlorinated pesticide contaminated soil. Results obtained for both types of biomass were similar: 80 to over 90% of gamma -hexachlorocyclohexane (gamma-HCH), 1,1,1-trichloro-2,2-bis-(4-methoxyphenyl)ethane (methoxychlor) and 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)ethane (DDT) removed in 4-6 weeks. Residual fractions of these pesticides persisted till the end of the 16-week experiment. DDT was degraded through 1,1-dichloro-2,2-bis-(4-chlorophenyl)ethane (DDD). Accumulation of this product corresponded stoichiometrically only to 34-53% of removed DDT, supposedly due to its further transformations, finally resulting in formation of detected 4,4'-dichlorobenzophenone (DBP). Addition of 0.5 mM Tween 80 nonionic surfactant resulted in about a twofold decrease of gamma -HCH and methoxychlor residual concentrations, as well as considerably lower DDD accumulation (7-29%) and higher DBP production. However, 1.25 mM dose of this surfactant applied together with granular sludge brought DDD levels back to that observed for treatments with the sludge alone, also impairing DBP formation.

Exposure assessment of breast-fed infants in the Czech Republic to indicator PCBs and selected chlorinated pesticides: area-related differences

The aim of our study was to obtain data on the exposure of breast-fed infants to polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) in different urban areas of the Czech Republic. The PCB and OCP levels were determined in 90 human milk samples collected in seven urban areas in 1999-2000 according to the WHO protocol. The estimated daily intake (EDI) was calculated for each of the analytes and compared with the respective tolerable daily intake (TDI). Significant local differences in the sum of 35 PCB congeners analyzed (total PCBs) as well as in the most prominent indicator congeners 138, 153, and 180 values were observed, with the highest levels being found in breast milk samples from mothers living in the vicinity of a former plant using PCBs in Uherské Hradiste (median and ranges 3410 and 1448-13,754 ng g(-1)lipid weight (lw)). Non-exposed mothers from the same area had about threefold lower levels (median and ranges 1073 and 757-2139 ng/g lw, respectively). The lowest levels of total PCBs were found in Telc (median and ranges 480 and 293-731 ng g(-1)lw, respectively). In all study areas, EDIs for PCBs in breast-fed infants exceeded the TDI of 0.4 microg kg(-1)bwd(-1) recommended in the Czech Republic. EDI for HCB exceeded the recommended TDI of 0.16 microg kg(-1), EDI for DDT was slightly below TDI of 10 microg kg(-1) bw d(-1) and HCHs EDI was negligible. The database of analytical results from this study was used for Bayesian modeling of breast-fed infant exposure to PCBs and OCPs during the recommended 6 months of exclusive breastfeeding.

Determination of Dechlorane Plus in serum from electronics dismantling workers in South China

Previous studies have reported high serum concentrations of polybrominated diphenyl ethers in residents of an electronic waste (e-waste) dismantling site in Guiyu town, South China. In this study, serum levels of Dechlorane Plus (DP), a chlorinated flame retardant of growing concern, were measured in residents of this region, and compared to those of a matched cohort from a nearby region in Haojiang, where fishing is the dominant industry. DP was detected in all the serum samples, with concentrations ranging from 7.8 to 465 ng/g lipid (median: 42.6 ng/g) and 0.93 to 50.5 ng/g lipid (median: 13.7 ng/g) in Guiyu and Haojiang, respectively. The Pearson's correlation coefficient between DP and decabromodiphenyl ether showed a positive relationship in Guiyu (r = 0.931, p < 0.01), but no correlation in Haojiang (r = 0.321, p = 0.34). The average anti-DP fractional abundances (f(anti) ratio) were 0.58 +/- 0.11 and 0.64 +/- 0.05 for Guiyu and Haojiang, respectively (p < 0.01). Tentatively identified dechlorination product ([-Cl + H]) was found in 19/40 serum samples (11/20 for Guiyu, 8/20 for Haojiang). These results suggest that the Guiyu and Haojiang cohorts experienced different dominant exposure routes. It is also possible that DP could bioaccumulate in a stereoselective manner, and undergo dechlorination metabolism. To the best of our knowledge, this is the first study to report DP levels in human serum. Further studies are needed to confirm the results of this study.

Accumulation of polychlorinated biphenyls and organochlorine pesticide in pet cats and dogs: assessment of toxicological status

PCB and DDT concentrations were determined in the adipose tissue of cats and dogs from Southern Italy. In cats p,p'-DDE was the most abundant DDT component (95.0%), while in dogs these compounds were absent, except in two specimens. PCB concentrations were higher in cats (199.02 ng g(-1) lipid weight) than in dogs (41.61 ng g(-1) lipid weight). Also there were inter-specific differences in the contribution of the different congeners to PCBs, although PCB 138, PCB 153 and PCB 180 were the most representative congeners in both species. Animals from one location, Taranto City, had significantly elevated concentrations of dioxin-like PCBs compared to the other locations. Consequently the estimated mean 2,3,7,8-tetrachlorodibenzo-p-dioxin toxic equivalents (TEQs) of coplanar PCBs were higher in these animals (cats: 0.65 pg g(-1) lipid weight; dogs 0.29 pg g(-1) lipid weight) than in the other ones (cats: 0.12 pg g(-1) lipid weight; dogs: 0.001 pg g(-1) lipid weight).

Long-term air monitoring of organochlorine pesticides using Semi Permeable Membrane Devices (SPMDs) in the Alps

Atmospheric sampling of organochlorine pesticides (OCPs) was conducted using Semi Permeable Membrane Devices (SPMDs) deployed in the Alps at different altitudinal transects for two consecutive exposure periods of half a year and a third simultaneous year-long period. Along all the altitude profiles, the sequestered amounts of OCPs increased in general with altitude. SPMDs were still working as kinetic samplers after half a year for the majority of the OCPs. However, compounds with the lowest octanol-air partition coefficient (K(oa)), reached equilibrium within six months. This change in the SPMD uptake was determined for the temperature gradient along the altitude profile influencing K(oa), OCPs availability in the gaseous phase, and SPMD performance. In sum, it seems two effects are working in parallel along the altitude profiles: the change in SPMD performance and the different availability of OCPs along the altitudinal transects determined by their compound properties and concentrations in air.

Multifunctional colloidal particles for in situ remediation of chlorinated hydrocarbons

Effective in situ injection technology for the remediation of dense nonaqueous phase liquids (DNAPLs) such as trichloroethylene (TCE) requires the use of decontamination agents that effectively migrate through the soil media and react efficiently with dissolved TCE and bulk TCE. We describe the use of a novel decontamination system containing highly uniform carbon microspheres in the optimal size range for transport through the soil. The microspheres are enveloped in a polyelectrolyte (carboxymethyl cellulose, CMC) to which a bimetallic nanoparticle system of zero-valent iron and Pd is attached. The carbon serves as a strong adsorbent to TCE, while the bimetallic nanoparticle system provides the reactive component. The polyelectrolyte serves to stabilize the carbon microspheres in aqueous solution. The overall system resembles a colloidal micelle with a hydrophilic shell (polyelectrolyte coating) and hard hydrophobic core (carbon). In contact with bulk TCE, there is a sharp partitioning of the system to the TCE side of the interface due to the hydrophobicity of the core. These multifunctional systems appear to satisfy criteria related to remediation and are made with potentially environmentally benign materials.

Atlantic bluefin tuna (Thunnus thynnus) population dynamics delineated by organochlorine tracers

Atlantic bluefin tuna (ABFT) are highly valued and heavily exploited, and critical uncertainties regarding their population structure hinder effective management. Evidence supports the existence of two breeding populations of ABFT; a western population in the Gulf of Mexico and an eastern population in the Mediterranean Sea; both of which migrate and mix in the North Atlantic. Conventional tagging studies suggest low rates of trans-Atlantic migrations; however, electronic tagging and stable isotopes in otoliths indicate stock mixing up to 57% between management zones delineated by 45 degrees W longitude. Here we show that organochlorine pesticides and polychlorinated biphenyls (PCBs) can be used as tracers of bluefin tuna foraging grounds in the North Atlantic and confirm that stock mixing of juvenile tuna within the U.S. Mid Atlantic Bight is indeed high (33-83% eastern origin), and is likely spatially and temporally variable. We further demonstrate that >10% of the Mediterranean population is migratory, that young bluefin tuna migrate from the Mediterranean to western Atlantic foraging grounds as early as age 1, and then return to the Mediterranean Sea as young as age 5, presumably to breed. The tracer method described here provides a novel means for distinguishing bluefin tuna populations and ontogenetic shifts in migration in the North Atlantic.

Quantitative structure - photodegradation relationships of polybrominated diphenyl ethers, phenoxyphenols and selected organochlorines

Among other developments, the technological revolution has lead to introduction of new chemicals to better serve in instruments and materials. The consequences of the extensive increase in use of new chemicals can be detected in the environment world wide, i.e. in wildlife and humans. To ensure this problem to be minimised in the future, new chemicals need to be subjected to predictive assessments before commercialised. To facilitate screening, qualitative structure-activity relationships, quantitative structure-activity relationships may be applied to describe reactivity of chemicals. Physico-chemical properties of chemicals such as partition coefficients and half-lives for the various environmental compartments are essential input data in multimedia environmental fate models. In this study we examine how structural characteristics can quantitatively describe laboratory determined photolytic half-lives of halogenated compounds of different classes, such as polybrominated diphenyl ethers (PBDEs), hydroxylated brominated diphenyl ethers (OH-PBDEs), and other organohalogens. A total of 30 chemicals with experimentally measured half-lives are used. Results reveal that the most important descriptors for describing the half-lives of the brominated compounds are the energy gap (GAP-1) between HOMO-1 and LUMO, the lowest partial charge on a halogen atom (Qhal-), topological polar surface area (TPSA), the atom with highest radical superdelocalizability (Rad-super+) and LUMO density (LUMO+).

Influence of Cu, Fe, Pb, and Zn chlorides and oxides on formation of chlorinated aromatic compounds in MSWI fly ash

Model fly ashes containing admixed Cu, Fe, Pb, and Zn chlorides and oxides were heated at a temperature corresponding to the postcombustion zone of a municipal solid waste incinerator (MSWI), resulting in the formation of chlorinated aromatic compounds, including polychlorinated dibenzo-p-dioxins (PCDDs) and furans (PCDFs), polychlorinated biphenyls (PCBs), and chlorobenzenes (CBzs). The concentrations of these compounds were measured and compared with those occurring in real fly ash. The order with respect generative capacity of each metal additive was calculated from principal component analysis of the concentrations of the different chlorinated aromatic compounds as CuCl(2)*2H(2)O > Cu(2)(OH)(3)Cl > FeCl(3)*6H(2)O > FeCl(2)*4H(2)O > CuO > Fe(2)O(3) > PbCl(2) > blank (no metal added) > ZnCl(2) > PbO > ZnO. From hierarchical cluster analysis of the concentrations and congener distribution patterns of the PCDDs, PCDFs, PCBs, and CBzs, the metallic compounds were divided into five groups: Group A (CuCl(2)*2H(2)O and Cu(2)(OH)(3)Cl), B (FeCl(3)*6H(2)O and FeCl(2)*4H(2)O), C (CuO and PbCl(2)), D (Fe(2)O(3), blank, and ZnCl(2)), and E (PbO and ZnO). Cluster analysis showed the congener distribution patterns of model fly ashes to be similar to the pattern of real MSWI fly ash. The formation of PCDDs was influenced mainly by group B, blank, and PbO; PCDFs, mainly by CuO, Fe(2)O(3) and ZnCl(2); PCBs, mainly by groups B and C; and CBzs, mainly by groups A and B. Thus, the multiple promotion of chlorinated aromatic compound formation by metallic chlorides and oxides in the fly ashes of MSWIs and other thermal processes has considerable importance for the environment.

Interactive effect of organic amendment and environmental factors on degradation of 1,3-dichloropropene and chloropicrin in soil

Soil organic matter is an important factor affecting the fate of soil fumigants; therefore, the addition of organic amendments to surface soils could reduce fumigant emissions by accelerating fumigant degradation. Experiments were conducted to determine the degradation of fumigants [a mixture of cis- and trans-1,3-dichloropropene (1,3-D) and chloropicrin (CP), a similar composition as in Telone C35] in soils with organic amendment under a range of soil moisture, temperature, sterilization, and texture conditions. Degradation of the fumigants followed availability-adjusted first-order or pseudo-first-order kinetics with slower degradation of 1,3-D than CP. Increasing soil water content from 5 to 17.5% (w/w) slightly increased the degradation of 1,3-D, but not that of CP. Five different organic amendments at 5% (w/w) increased fumigant degradation 1.4-6.3-fold in this study. The degradation of both fumigants was accelerated with increasing amount of organic material (OM). Little interaction between soil moisture and OM was observed. Autoclave sterilization of soils did not reduce degradation of either fumigant; however, increasing the incubation temperature from 10 to 45 degrees C accelerated fumigant degradation 5-14 times. Soil texture did not affect 1,3-D degradation, but CP degraded more rapidly in finer-textured soil. These results suggest that OM type and rate and soil temperature are the most important factors affecting the degradation of 1,3-D and CP.

Degradation of chlorinated butenes and butadienes in granular iron columns

Manufacturing facilities for production of chlorobutyl rubber have the potential to release a mixture of at least 5 chlorinated butenes and butadienes including trans-1,4-dichlorobutene-2 (1,4-DCB-2), 3,4-dichlorobutene-1 (3,4-DCB-1), 2,3,4-trichlorobutene-1 (TCB), 2-chlorobutadiene-1,3 (chloroprene) and 2,3-dichlorobutadiene-1,3 (DCBD) into groundwater environment. To evaluate the potential of using granular iron in the remediation of the above contaminants, a series of column experiments were conducted. Degradation of all 5 compounds followed pseudo-first-order kinetics. The three chlorinated butenes degraded much faster (surface area normalized half-lives, t(1/2)', ranged from 1.6 to 5.2 min m2/mL) than the 2 chlorinated butadienes (t(1/2)' ranged from 102 to 197 min m2/mL). All contaminants fully dechlorinated by granular iron to 1,3-butadiene as a common reaction intermediate that then degraded to a mixture of relatively non-harmful end products consisting of 1-butene, cis-2-butene, trans-2-butene and n-butane. Based on the kinetic data, product distributions, and chlorine mass balances, reaction pathways for these compounds are proposed. For the chlorinated butenes, 3,4-DCB-1 and TCB, undergo reductive beta-elimination reactions resulting in 1,3-butadiene and chloroprene intermediates. Dechlorination of 1,4-DCB-2 to 1,3-butadiene occurs through a reductive elimination similar to reductive beta-elimination. For dechlorination of the two chlorinated butadienes, chloroprene and DCBD, dechlorination occurs through a hydrogenolysis pathway. The common non-chlorinated intermediate, 1,3-butadiene, undergoes catalytic hydrogenation resulting in a mixture of butane isomers and n-butane. The results suggest that granular iron is an effective material for treatment of groundwater contaminated with these compounds.

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.