Polychlorinated biphenyls hot and cold seasons distribution in see water,sediment, and fish samples in the Khour-e-Mousa (Mah-Shahr), Iran

The concentrations of polychlorinated biphenyls (PCBs) were assessed at four sites in Khour-e-Mousa (Mah-Shahr), Iran. Sea water, sediment and fish (cynoglossus bilineatus) samples were taken at each site and were analysed for PCB levels. To investigate the possible source of PCBs found in fish samples, sediments and waters were collected from four sites (D1, D2, D3, and D4) and studied. The relationship between PCB concentrations in sediment, water and fish is discussed. The results indicate that PCBs are detected in all fish samples and its concentration range from 3.2 to 102.7 μg kg^?1 dry weight and 5.4–149.7 μg kg^?1 dry weight in cold and warm seasons, respectively. The D2 and D4 sites were found to have the highest and lowest levels of PCB concentrations, respectively. Total congener PCB (CB, 28, 52, 44, 101, 149, 118, 153, 138, and 180) concentrations at the sediment samples for D1, D2, D3, and D4 sites ranged from 1.6 to 30.9 μg kg^?1 dry weight and 2.3–47.1 μg kg^?1 dry weight in cold and warm seasons, respectively. The total PCB concentrations for D2 site were found to be significantly higher than other three sites. Total water congener PCB (CB, 28, 52, 44, 101, 149, 118, 153, 138, and 180) concentrations ranged from 0.01 to 0.25 μg L^?1 and 0.02–0.39 μg L^?1 in cold and warm seasons, respectively.     

Atmospheric polychlorinated biphenyl concentrations and apparent degradation in coastal New Jersey

To characterize the atmospheric dynamics and behavior of organic compounds in the NY–NJ Harbor Estuary, atmospheric concentrations of polychlorinated biphenyls (PCBs) were measured at coastal, suburban and urban sites in New Jersey in 1997–1999. ∑PCB concentrations at the suburban site varied from 86 to 2300 pg m⁻³ and from 84 to 1100 pg m⁻³ at the coastal site. Although the temporal trends of total concentrations were significantly different at the three sites (p<0.01), PCB congener profiles revealed similar patterns (r²>0.90, p<0.001) implicating a dominant emission type and/or process. Temperature explained >50% of the total variability in ln[PCB] at both sites. Atmospheric concentrations at the suburban site increased when winds blew from an eastnortheast vector, while increased wind speeds led to a slight dilution. Wind speed and direction were not significantly correlated with the concentrations measured at the coastal site. Temporal changes in congener distribution at the suburban site are consistent with the preferential atmospheric removal of 3–5 Cl-biphenyls by hydroxyl radical attack with estimated half-lives of 0.7–1.8 years.     

Assessment of exposure to PCB 153 from breast feeding and normal food intake in individual children using a system approach model

Investigators have typically relied on a single or few discrete time points as measures of polychlorinated biphenyl (PCB) body burden, however health effects are more likely to be the result of integrative exposure in time, optionally expressed as an area under the time curve (AUC) of PCB serum concentration. Using data from a subgroup of 93 infants from a birth cohort in eastern Slovakia—a region highly polluted by PCBs—we fit a system type model, customized to our longitudinal measures of serum PCB concentrations in cord, 6, 16, and 45 month blood specimens. The most abundant congener, PCB 153, was chosen for modeling purposes. In addition to currently used methods of exposure assessment, our approach estimates a concentration time profile for each subject, taking into account mean residence time of PCB 153 molecules in the body, duration of breast feeding, hypothetical PCB 153 concentration in steady-state without breast feeding and alternately without normal food intake. Hypothetical PCB 153 concentration in steady-state without normal food intake correlates with AUC (r = 0.84, p < 0.001) as well as with duration of breast feeding (r = 0.64, p < 0.001). It makes possible to determine each subject’s exposure profile expressed as AUC of PCBs serum concentration with a minimum model parameters. PCB body burden in most infants was strongly associated with duration of breast feeding in most, but not all children, was apparent from model output.     

Accumulation of hydroxylated polychlorinated biphenyls (OH-PCBs) and implications for PCBs metabolic capacities in three porpoise species

The present study investigated polychlorinated biphenyls (PCBs) and hydroxylated metabolites of PCBs (OH-PCBs) in blood from three porpoise species: finless porpoises (Neophocaena phocaenoides), harbor porpoises (Phocoena phocoena), and Dall’s porpoises (Phocoenoides dalli). The porpoises were found stranded or were bycaught along the Japanese coast. Concentrations of OH-PCB were the highest in Dall’s porpoises (58 pg g⁻¹ wet wt), second highest in finless porpoises (20 pg g⁻¹ wet wt), and lowest in harbor porpoises (8.3 pg g⁻¹ wet wt). The concentrations in Dall’s porpoises were significantly higher than the concentrations in finless porpoises and harbor porpoises (p < 0.05 and p < 0.01, respectively). There was a positive correlation between PCB and OH-PCB concentrations (r = 0.67, p < 0.001), suggesting the possible concentration-dependent induction of CYP enzymes. The three porpoise species may have exceptionally low metabolic capacities compared with other marine and terrestrial mammals, because low OH-PCB/PCB concentration ratios were found, which were 0.0016 for Dall’s porpoises, 0.0013 for harbor porpoises, and 0.00058 for finless porpoises. Distinct differences in the OH-PCB congener patterns were observed for the three species, even though they are taxonomically closely related.     

Atmospheric deposition of organochlorine contaminants to Galveston Bay,Texas

Atmospheric monitoring of PCBs and chlorinated pesticides (e.g., HCHs, chlordanes, and DDTs) in Galveston Bay was conducted at Seabrook, Texas. Air and wet deposition samples were collected from 2 February 1995 and continued through 6 August 1996. Vapor total PCB (tPCB) concentrations in air ranged from 0.21 to 4.78 ng m⁻³ with a dominance of tri-chlorinated PCBs. Dissolved tPCBs in rain ranged from 0.08 to 3.34 ng l⁻¹, with tetra-chlorinated PCBs predominating. The predominant isomers found in air and rain were α- and γ-HCH, α- and γ-chlordanes, 4,4′-DDT, and dieldrin. The concentrations of PCBs and pesticides in the air and rain revealed no clear seasonal trend. Elevated levels of PCBs in the air occurred when temperatures were high and wind came from urban and industrialized areas (S, SW, NW, and W of the site). Concentrations of HCHs were elevated in April, May, and October, perhaps due to local and/or regional applications of γ-HCH (lindane). Other pesticides showed no notable temporal variation. When winds originated from the Gulf of Mexico (southeasterly), lower concentrations of organochlorines were detected in the air. The direct deposition rate (wet+dry) of PCBs to Galveston Bay (6.40 μg m⁻² yr⁻¹) was significantly higher than that of pesticides by a factor of 5–10. The net flux from gas exchange estimated for PCBs was from Galveston Bay water to the atmosphere (78 μg m⁻² yr⁻¹). Gas exchange of PCBs from bay water to the atmosphere was the dominant flux.     

Blood levels of PCDDs,PCDFs, and coplanar PCBs in Yusho mothers and their descendants: Association with fetal Yusho disease

Maternal exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) may result in adverse health effects in their children. In Japan in 1968, an accidental human exposure to rice oil contaminated with PCDDs, PCDFs, and PCBs, led to the development of Yusho disease. Yusho mothers delivered descendants with low birth weights and hyperpigmented skin and mucosa, which are characteristic of fetal Yusho disease (FYD). The Yusho cohort was used to evaluate the effect of maternal exposure to PCDDs, PCDFs, and PCBs on the development of FYD. Blood samples, obtained from 64 Yusho mothers (117 descendants: 10 with FYD and 107 without FYD), were analyzed for congeners of seven PCDDs, 10 PCDFs, and four coplanar PCBs. We investigated the association between the maternal estimated blood levels of dioxins at delivery and the risk of fetal Yusho disease. We also studied the differences in dioxin blood levels in 24 mother–descendant pairs (5 with FYD and 19 without FYD). The estimated levels of total PCDD TEQ, total PCDF TEQ, total coplanar PCB TEQ, and total TEQ in the maternal blood at delivery were associated with significantly increased risk of FYD. The odds ratios, which present the risk of FYD for a 10-fold increase in blood dioxin, were largest for 1,2,3,6,7,8-HexaCDD (odds ratio = 28.6, 95% confidence interval = 1.67–489.9, p = 0.02). The levels of 1,2,3,6,7,8-HexaCDD in both the Yusho mothers and their descendants with FYD were higher than the levels in those without FYD. These findings suggest that 1,2,3,6,7,8-HexaCDD is the most important causative congener for the development of FYD.     

Organochlorine pesticides and polychlorinated biphenyls in soil and water samples in the Northeastern part of São Paulo State,Brazil

Detailed analyses of persistent organic pollutants (POPs) such as organochlorine pesticides (OCPs), hexachlorocyclohexane (HCH) isomers (HCHs), dichlorodiphenyltrichloro ethane (DDT) and its metabolites (DDTs) and congeners of polychlorinated biphenyls (PCBs) in soil and surface water from the northeastern São Paulo, Brazil allowed the evaluation of the contamination status, distribution and possible pollution sources. The pesticides and PCBs demonstrated markedly different distributions, reflecting different agricultural, domestic and industrial usage in each region studied. The ranges of HCH, DDT, and PCBs concentrations in the soil samples were 0.05–0.92, 0.12–11.01, 0.02–0.25 ng g⁻¹ dry wt, respectively, and in the surface water samples were 0.02–0.6, 0.02–0.58 and 0.02–0.5 ng l⁻¹, respectively. Overall elevated levels of DDT and PCB were recorded in region 2, a site very close to melting, automotive batteries industries, and agricultural practice regions. High ratios of metabolites of DDT to DDT isomers revealed the recent use of DDT in this environment. The sources of contamination are closely related to human activities, such as domestic and industrial discharge, street runoff, agricultural pesticides and soil erosion, due to deforestation as well as atmospheric transport.     

Measurement of the vapor phase deposition of polychlorinated bipheyls (PCBs) using a water surface sampler

A water surface sampler (WSS) was employed in combination with greased knife-edge surface deposition plates (KSSs) to measure the vapor phase deposition rates of PCBs to the sampler at an urban site, Chicago, IL. This sampler employed a water circulation system that continuously removed deposited PCBs. Total (gas+particle) and particulate PCB fluxes were collected with the WSS and KSSs, respectively. Gas phase PCB fluxes were then calculated by subtracting the KSS fluxes (particulate) from the WSS fluxes (gas+particle). The calculated gas phase PCB fluxes averaged 830±910 ng m⁻²d⁻¹. This flux value is, in general, higher than the fluxes determined using simultaneously measured air–water concentrations in natural waters and is in the absorption direction. This difference is primarily because the PCBs were continuously removed from the WSS water keeping the water PCB concentration near zero.Concurrently, ambient air samples were collected using a modified high volume air sampler. The gas phase PCB concentrations ranged between 1.10 and 4.46 ng m⁻³ (average±SD, 2.29±1.28 ng m⁻³). The gas phase fluxes were divided by the simultaneously measured gas phase ambient concentrations to determine the overall gas phase mass transfer coefficients (MTCs) for PCBs. The average gas phase overall MTCs (K_g) for each homolog group ranged between 0.22 and 1.32 cm s⁻¹ (0.54±0.47 cm s⁻¹). The average MTC was in good agreement with those determined using similar techniques.     

Polychlorinated biphenyls and particulate organic/elemental carbon in the atmosphere of Chesapeake Bay,USA

Polychlorinated biphenyls (PCBs) and particulate organic/elemental carbon (OC/EC) differ as to sources, but are both elevated in major urban areas leading to loadings of proximate terrestrial and aquatic systems. Because of the dramatic difference in speciation, sources, and sinks of these compunds, gas+particulate phase PCBs and particulate OC/EC were measured in urban Baltimore, MD and over Chesapeake Bay at 4 and 12 h frequencies in July 1997. Gas phase ∑PCBs averaged 1180 pg m⁻³ for Baltimore and 550 pg m⁻³ for northern Chesapeake Bay. PCB homolog distributions in the gas phase differed between the land and over-water sites whereby the trichlorobiphenyls were higher in Baltimore compared to Chesapeake Bay. Autocorrelation analysis yielded a diurnal cycle for gas phase PCBs at Baltimore with the lowest concentrations observed during the day. Particulate organic and elemental carbon constituted 12.4% (17.4% organic matter) and 2.8% of total suspended particles (TSP) in Baltimore, and 15.0% (21.0% organic matter) and 5.3% over the Chesapeake Bay, respectively. Variability in PCB concentrations was not related to the variability in OC/EC concentrations. OC/EC ratios suggest that particulate organic carbon was mostly primary aerosol. Emissions of both classes of compounds into the Baltimore atmosphere and vicinity are major sources to the Bay.     

Spatio-temporal trends of PCBs in the Swedish freshwater environment 1981–2012

Polychlorinated biphenyls (PCBs) have been monitored in perch (Perca fluviatilis), pike (Esox lucius), and Arctic char (Salvelinus alpinus) in reference lakes since the late 1960s. Temporal trends and spatial patterns are currently monitored in nine and 32 lakes, respectively. Overall, PCB concentrations are decreasing. However, this is not consistent for all congeners across all lakes and species. Perch has comparatively low PCB concentrations relative to suggested target levels, but individual congener concentrations in some lakes are concerningly high. No temporal trend is seen for CB-118 and CB-153 in perch, but significant decreasing trends exist for Arctic char and pike, for which monitoring started earlier than for perch. The lower/higher chlorinated congener ratio decreased over time in most lakes, indicating fewer new emissions. CB-118 and CB-153 concentrations in perch show spatial gradients across Sweden, with higher concentrations found near urban/industrial areas.     

Bioaccumulation of polybrominated diphenyl ethers in harbor seals from the northwest Atlantic

Polybrominated diphenyl ethers (PBDEs) were analyzed in blubber of harbor seals (Phoca vitulina concolor) collected between 1991 and 2005 along the northwest Atlantic. ∑PBDE concentrations (mono- to hexa-BDEs) detected in blubber samples (n = 42) ranged from 80 to 25 720 ng g⁻¹ lw, (overall mean 2403 ± 5406 ng g⁻¹ lw). By age, mean ∑PBDE concentrations were: 3645 ± 7388, 2945 ± 5995, 1385 ± 1265, and 326 ± 193 ng g⁻¹ lw in pups, yearlings, adult males, and adult females, respectively. Unlike the trend for PCBs, no decreasing gradient from urban to rural/remote areas was observed for PBDEs in these samples, likely reflecting inputs from local sources. No significant temporal trend was observed for PBDEs in harbor seals between 1991 and 2005, although congener profiles shifted over time. Tetra-BDE-47 was the dominant congener, followed by BDEs-99, -100, -153, -154, and -155 in varying order, suggesting exposure to the penta-BDE product. In adult males, the hexa-BDEs contributed more to the total (22%) than BDEs-99 and -100 (14%), and concentrations of BDE-155 were elevated compared with -154. Higher BDEs were detected in a subset of seals (n = 12) including hepta-BDE-183, the marker for the octa-BDE mixture, and octa-BDE-197, along with several unidentified hepta- and octa- congeners. BDE-209 was detected in seal blubber at concentrations ranging from 1.1 to 8 ng g⁻¹ lw, indicating that deca-BDE is bioavailable in this marine food web. This is the first study to document the accumulation of BDE-209 at measurable levels in wild harbor seals. While the PBDE patterns in blubber indicate exposure to all three BDE commercial mixtures, the data also suggest that BDE-209 debromination by seal prey fish may contribute to the loading of lower brominated congeners (hexa- to octa-BDEs) in these seals.     

Compound specific carbon and hydrogen stable isotope analyses of volatile organic compounds in various emissions of combustion processes

This study presents carbon (δ¹³C) and hydrogen (δD) isotope values of volatile organic compounds (VOCs) in various emission sources using thermal desorption–gas chromatography–isotope ratio mass spectrometry (TD–GC–irMS). The investigated VOCs ranged from C6 to C10. Samples were taken from (i) car exhaust emissions as well as from plant combustion experiments of (ii) various C3 and (iii) various C4 plants. We found significant differences in δ values of analysed VOCs between these sources, e.g. δ¹³C of benzene ranged between (i) −21.7 ± 0.2‰, (ii) −27.6 ± 1.6‰ and (iii) −16.3 ± 2.2‰, respectively and δD of benzene ranged between (i) −73 ± 13‰, (ii) −111 ± 10‰ and (iii) −70 ± 24‰, respectively. Results of VOCs present in investigated emission sources were compared to values from the literature (aluminium refinery emission). All source groups could be clearly distinguished using the dual approach of δ¹³C and δD analysis. The results of this study indicate that the correlation of compound specific carbon and hydrogen isotope analysis provides the potential for future research to trace the fate and to determine the origin of VOCs in the atmosphere using thermal desorption compound specific isotope analysis.     

Persistent organochlorine pesticide and PCB residues in surface sediments of Lake Qarun,a protected area of Egypt

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were determined in sediment samples collected from 34 locations in Lake Qarun, Egypt to elucidate their concentrations, distribution, possible sources and potential ecological risk. A total of 25 OCPs and 29 PCBs were identified and quantified. OCPs and PCBs were found to be ubiquitous pollutants in the aquatic environment of Lake Qarun, particular near urban areas reflecting the local usage and input of these pollutants. Total concentrations of OCPs and PCBs in sediments ranged from 1.01 to 164.8 ng g^?1 and 1.48 to 137.2 ng g^?1, respectively. Among OCPs, γ-HCH, heptachlor, aldrin, endrin, p,p′-DDE, oxy-chlordane and endosulfan I and II were the most abundant compounds. The composition of PCB congeners was dominated by the tri-, tetra-, penta- and hexa-chlorinated biphenyls. The ratios of certain metabolites (isomers) to their parent compounds (mixtures) indicated there are still new inputs of lindane, endrin, heptachlor and technical endosulfan to Qarun Lake, while the ratios of (p,p′-DDE + p,p′-DDD)/∑p,p′-DDTs indicate earlier usage of DDT. Contamination levels of PCBs and HCHs can be categorized as moderate to high compared to other urbanized regions worldwide. According to established sediment quality guidelines, γ-HCH, endrin and chlordanes would be more concerned OCP species for the ecotoxicological risk in Lake Qarun.     

Identification of sources affecting fog formation using receptor modeling approaches and inventory estimates of sectoral emissions

Positive matrix factorization (PMF) was used to identify factors affecting fog formation in Kanpur during the ISRO-GBP land campaign-II (LC-II) in December 2004. PMF predicted factors were validated by contrasting the emission strength of sources in the foggy and clear periods, using a combination of potential source contribution function (PSCF) analysis and quantitative emission inventory information. A time series aerosol chemical data set of 29 days and 12 species was decomposed to identify 4-factors: Secondary species, Biomass burning, Dust and Sea salt. PMF predicted particle mass with a satisfactory goodness-of-fit (slope of 0.83 ± 0.17 and R² of 0.8), and strong species within 11–12% relative standard deviation. Mean contributions of anthropogenic factors were significantly higher during the foggy period for secondary species (2.9 ± 0.3) and biomass burning (1.2 ± 0.09) compared to the clear period. Local sources contributing to aerosols that mediated fog events at Kanpur, based on emissions in a 200 km × 200 km area around Kanpur city were thermal power plants and transportation (SO₂) and biofuel combustion (BC and OM). Regional scale sources influencing emissions during the foggy period, in probable source regions identified by PSCF included thermal power plants, transportation, brick kilns and biofuel combustion. While biofuel combustion and transportation are distributed area sources, individual point sources include coal-fired thermal power plants located in Aligarh, Delhi, Ghaziabad, Jhansi, Kanpur, Rae Bareli and Rupnagar and brick kilns located in Allahabad, Agra, Farrukhabad, Ghaziabad, Kanpur, Ludhiana, Lucknow and Rae Bareli. Additionally, in the foggy period, large areas of probable source regions lay outside India, implying the significance of aerosol incursion from outside India.     

Seasonal variation of organochlorine contaminants in bonito (Sarda sarda L. 1758) and anchovy (Engraulis encrasicolus L. 1758) in Black Sea region,Turkey

The concentrations of indicator polychlorinated biphenyls (PCBs) and organochlorine insecticides were determined in bonito (Sarda sarda L. 1758) and anchovy (Engraulis encrasicolus L. 1758) from the Black Sea, Turkey. Concentrations of total indicator PCBs ranged between <1–17.0 in bonito, and <1–17.5 ng/g fresh weight in anchovy, and total of 1,1,1-trichloro-2,2-bis-chlorophenyl-ethane and its metabolites’ (DDTs) concentrations ranged between 13.4–26.3, and 2.96–19.0 ng/g fresh weight in bonito and anchovy respectively. PCB 52, p,p′-DDE and endosulfan (α + β) were found dominant in both of the fish species. Except endosulfan, and some DDT metabolites, none of the studied organochlorine pesticides was detected in the fish samples. Concentrations of PCBs in anchovy were found higher than those in bonito, whereas DDT and endosulfan concentrations were found similar in both of the fish species. All of the fish samples had residue concentrations below the maximum residue limits (MRL) recommended by FAO/WHO Codex Alimentarius Commission.     

Levels of persistent organic pollutants in air in China and over the Yellow Sea

The occurrence of persistent toxic substances (PTS) in China and possibly their regional transport in the Yellow and East China Seas region was studied. Organochlorines in atmospheric gas-phase and particulate matter were collected by high-volume sampling (filters and polyurethane foams) during 2 weeks in June 2003 (dry season) simultaneously at a Yellow Sea coastal site in an urban area, Qingdao, China, and a rural island site, Gosan, Jeju Island, Korea. Using GC methods, the samples were analysed for 9 persistent organic pollutants (POPs) regulated under the global POP convention, namely aldrin, chlordane (cis- and trans-isomers CC and TC), DDT and metabolites (o,p′-DDT, p,p′-DDD, and p,p′-DDE), dieldrin, endrin, heptachlor, hexachlorobenzene (HCB), mirex and PCB (congeners number 28, 52, 101, 153 and 180), and for hexachlorocyclohexane (α-, β- and γ-isomers), a PTS and now considered for regulation under the convention, too. At the coastal site additionally o,p′-DDE and -DDD, β-endosulfan, isodrin, heptachlorepoxide and δ-HCH, and at the island site additionally p,p′-DDT and 12 additional PCB congeners were analysed. 9 samples were collected at the coastal and 15 (for PCBs 5) at the island site. Long-range advection pathways were determined based on analysed back-trajectory calculations.The mean concentrations of DDT and its metabolites, HCB, HCH, and PCB at the coast were in the 100–1000 pg m⁻³ range. Higher concentrations prevailed during nighttime. The levels were in general lower at the island site, but not for DDT. Local sources are likely. PCBs were even 2 orders of magnitude lower, suggesting that PCBs are not subject to regional transport but elevated concentrations in air are limited to the source areas. Organochlorine pesticide levels on the other hand were seemingly determined by regional transport over Mainland China rather than by emissions in the coastal area. The currently used pesticides mirex and chlordane were found at elevated levels, i.e. 79 (6.6–255) and 36 (<6–71) pg m⁻³, respectively, at the coast but not over the island. The POPs pesticides aldrin, dieldrin and endrin, never registered in China, were mostly found at <10 pg m⁻³ except for endrin at the coastal site (up to 400 pg m⁻³) and aldrin at the island site (up to 50 pg m⁻³).     

Polychlorinated biphenyl spatial patterns in San Francisco Bay forage fish

Industrialized waterways frequently contain nearshore hotspots of legacy polychlorinated biphenyl (PCB) contamination, with uncertain contribution to aquatic food web contamination. We evaluated the utility of estuarine forage fish as biosentinel indicators of local PCB contamination across multiple nearshore sites in San Francisco Bay. Topsmelt (Atherinops affinis) or Mississippi silverside (Menidia audens) contamination was compared between 12 targeted sites near historically polluted locations and 17 probabilistically chosen sites representative of ambient conditions. The average sum of 209 PCB congeners in fish from targeted stations (441 ± 432 ng g^?1 wet weight, mean ± SD) was significantly higher than probabilistic stations (138 ± 94 ng g^?1). Concentrations in both species were comparable to those of high lipid sport fish in the Bay, strongly correlated with spatial patterns in sediment contamination, and above selected literature thresholds for potential hazard to fish and wildlife. The highest concentrations were from targeted Central Bay locations, including Hunter’s Point Naval Shipyard (1347 ng g^?1; topsmelt) and Stege Marsh (1337 ng g^?1; silverside). Targeted sites exhibited increased abundance of lower chlorinated congeners, suggesting local source contributions, including Aroclor 1248. These findings indicate that current spatial patterns in PCB bioaccumulation correlate with historical sediment contamination due to industrial activity. They also demonstrate the utility of naturally occurring forage fish as biosentinels of localized PCB exposure.     

Impact of PCB-118 and transformer oil toxicity on anaerobic digestion of sludge: Anaerobic toxicity assay results

In this study, possible toxicity of increasing doses of PCB-118 and transformer oil (TO) on anaerobic sludge digestion was investigated. For this purpose, five different sets of reactors were prepared in which four different PCB-118 concentration (1, 10, 20, and 30 mg L⁻¹) and three different TO concentration (0.38, 0.76, and 1.52 g L⁻¹) were applied. Throughout the study, biogas production and composition, pH, TS, VS, and COD as well as PCB concentration were monitored. Toxicity was investigated by anaerobic toxicity assay (ATA) evaluating the reduction in methane production. A notable inhibition was observed mostly in 30 mg L⁻¹ PCB reactors. A negative influence of PCB-118 and TO was observed on COD and solids removal. A maximum of 26.5% PCB-118 removal was attained.     

Volatile organic compounds in roadside microenvironments of metropolitan Hong Kong

The characteristics and concentrations of volatile organic compounds (VOCs) in the roadside microenvironments of metropolitan Hong Kong were investigated. The VOC concentrations, especially toluene, benzene and chlorinated VOCs in Hong Kong were high when compared with those in most developed cities. The average and maximum concentration of toluene was 74.9 and 320.0 μg m⁻³, respectively. The respective values for benzene were 25.9 and 128.6 μg m⁻³. The chlorinated VOCs were dominated by trichloroethylene and tetrachloroethylene. The maximum concentrations of these two species reached 248.2 and 144.0 μg m⁻³, respectively. There were strong variations in the spatial fluctuation and characteristic of VOC concentrations. The highest VOC concentrations were found in the industrial district, which were followed by those in the commercial district, the central business district and finally the residential district. The highest concentrations of most VOC species, especially chlorinated VOC were found in the industrial and commercial districts. The average benzene/toluene ratio in Hong Kong was 0.5 suggesting that vehicular emission was the dominant VOC source in most areas of Hong Kong. There were strong deviations in benzene/toluene, benzene/ethylbenzene and benzene/(m+p-xylene) ratios in the commercial district, and highly chlorinated VOC in the industrial and commercial districts. These suggest that there were other benzene and VOC sources overlying on the high background VOC concentrations in these districts. The common usage of organic solvents in the building and construction industries, and in the small industries in the industrial and commercial districts were believed to be important sources of VOC in Hong Kong.     

Heavy metal distribution in dust from elementary schools in Hermosillo,Sonora, México

The city of Hermosillo, Sonora in northern Mexico was investigated for its heavy metals content. Samples of sedimented dust in roofs from 25 elementary schools were analyzed for their contents of Ni, Cr, Zn, Cd, Co, Ba, V, Pb, Fe and Cu after digestion with nitric acid. The results of the analysis were used to determine spatial distribution and magnitude of heavy metals pollution. The results of this study reveal that heavy metals distribution is different in two areas of the city. The southern area contains higher concentrations of heavy metals than the northcentral area. The mean level of Cd in exterior dust is 5.65 mg kg⁻¹ in the southern area whereas the mean level of Cd is 2.83 mg kg⁻¹ in the northcentral area. Elevated concentrations of Zn (2012 mg kg⁻¹), Pb (101.88 mg kg⁻¹), Cr (38.13 mg kg⁻¹) and Cd (28.38 mg kg⁻¹) in roof dust were found in samples located near industrial areas. Principal component analysis (PCA) was applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. PCA shows two main sources: (1) Pb, Cd, Cr and Zn are mainly derived from industrial sources, combined with traffic sources; (2) Fe, Co and Ba are mainly derived from natural sources. V and Ni are highly correlated and possibly related to fuel combustion processes. Enrichment factors were calculated, which in turn further confirms the source identification. Ba and Co are dominantly crustal. Anthropogenically added Cd, Pb, Zn and Cr show maximum enrichment relative to the upper continental crustal component. The distribution of the heavy metals in dust does not seem to be controlled only by the topography of the city, but also by the location of the emission sources.