Background air levels of polychlorinated biphenyls in China

Measurements of the atmospheric concentrations of polychlorinated biphenyls (PCBs) were taken in 11 background sites geographically distributed throughout China. Active high-volume samplers were employed during two deployment periods between November 2007 and November 2008. 12 dioxin-like and 7 indicator PCBs were identified and measured. To keep the consistency, the two sampling periods were set in the same seasons (autumn and winter) and there were few variations between the results at all sites. The congener profile of indicator PCBs was dominated by CB28 and CB52. The most abundant mono-ortho congener was CB118, and the most abundant non-ortho congener was CB77. This study is the first systematic investigation into background atmospheric PCB levels in China. The background indicator ∑₇PCB levels in China are similar to those obtained at other background areas around the world.     

Acute non-cancer mortality excess after polychlorinated biphenyls and polychlorinated dibenzofurans mixed exposure from contaminated rice oil: Yusho

In Japan in 1968, rice-oil contaminated by polychlorinated biphenyls and polychlorinated dibenzofurans caused severe food poisoning, termed “Yusho” (oil disease). Several previous studies attempted to evaluate the effects targeting officially-certified Yusho patients. However, these studies have several limitations such as the left-truncated nature of the registry or residual confounding arising from the referent population selection. We thus conducted an area-based standardized mortality ratios (SMRs) study using vital statistics. A severely affected area (Tamanoura area) was adopted as the exposure group, with a reference population from Nagasaki prefecture in Kyushu, which included the Tamanoura. A large number of residents in Tamanoura were exposed to the rice-oil (28% of all the certified cases as of 2009). We estimated SMRs of non-cancer and cancer diseases for the years 1968-2002. Shortly after the exposure, SMRs of all causes, diabetes mellitus, cardiovascular disease, pneumonia/bronchitis, and bronchus/lung cancer were elevated. In particular, SMRs of heart disease were 1.97 [95% confidence intervals (CI): 1.09-3.56] in 1968, 2.05 (95% CI: 1.16-3.60) in 1969, and 1.89 (95% CI: 1.05-3.41) in 1975. However, we did not observe clear increase in SMRs more than 10 years after the exposure. This study provides further evidence in Yusho, especially on acute effects on non-cancer mortality.     

Identification of subwatershed sources for chlorinated pesticides and polychlorinated biphenyls in the Ballona Creek watershed

Santa Monica Bay forms part of the western border of the greater Los Angeles region. The Ballona Creek watershed is highly urbanized and past studies indicate that Ballona Creek is the largest source for most pollutants to Santa Monica Bay. This study evaluates the contribution of subwatersheds to PCB and chlorinated pesticide loading during wet weather flow. Fifteen storm drains from these subwatersheds were sampled during three storms during the 2005-2006 winter rainy season. A series of grab samples were taken over the duration of the storms. The suspended solids were analyzed for polychlorinated biphenyls (PCBs) and chlorinated pesticides. A geographic information system (GIS) was used to calculate the runoff volume from each subwatershed to estimate pollution mass loading. There was no statistical difference among subswatersheds; however, a disproportionate mass of PCB loading came from site 5, which had no obvious sources. No specific subwatersheds were identified as key sources for chlorinated pesticides. These results may serve as a model for other locations with concerns for historic PCB and chlorinated pesticides loadings.     

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).     

The kinetics and reversibility of the partitioning of polychlorinated biphenyls between air and ryegrass

Lolium multiflorum (ryegrass) was contaminated with technical mixtures of polychlorinated biphenyls (PCBs) via the gas phase and the subsequent elimination of the PCBs from the vegetation was studied under field conditions. There was a pronounced decrease in the concentrations of the di- through to the pentachlorinated congeners over the 240-h elimination period. For many of the congeners the elimination was nearly complete, suggesting that the partitioning of these compounds from the gas phase into ryegrass is largely reversible. The elimination followed first order kinetics. The elimination half-lives were linearly proportional to the plant/air equilibrium partition coefficients (K(PA)) of the PCB congeners and ranged from 22 h for PCBs 8 + 5 to 87 h for PCBs 84 + 101. For the hexa- through to the octachlorinated congeners no significant decrease in the concentration of the vegetation was observed during the elimination experiment. The elimination was described well using a two-resistance model of PCB desorption which indicated that elimination of the di- and trichlorinated PCBs was limited by transport within the plant itself while elimination of the higher chlorinated congeners was limited by transport from the plant surface into the atmosphere. Furthermore, the results demonstrate that if elimination of higher chlorinated PCBs from ryegrass via biological or photochemical degradation occurs, then it is very slow.     

Relationship between serum concentrations of polychlorinated biphenyls and organochlorine pesticides and dietary habits of pregnant women in Shanghai

The use of most polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) has been restricted in China; however, their use remains a concern because of their adverse effects on human health, especially on fetuses and infants. To date, there is no data regarding the exposure levels of pregnant women to PCBs and OCPs in Shanghai. In order to evaluate PCB and OCP exposure levels and the contribution of dietary habits to these levels, we determined the concentrations of 8 PCBs and 14 OCPs in the umbilical cord blood serum of healthy pregnant women in Shanghai. Dietary habits of the pregnant women were obtained from a self-administered questionnaire. Results showed that p, p′-DDE, HCB and β-HCH were the major pollutants present in the serum samples; PCBs were detected in a few samples at low concentrations. Age, weight and body mass index before delivery were positively associated with serum levels of p, p′-DDE and β-HCH. Women and their husbands who had higher education levels, higher income levels, tended to have higher levels of p, p′-DDE and β-HCH. Spearman correlation analysis results suggested that consumption of foods such as milk, eggs, meat, fish, and shrimp may contribute to higher serum levels of p, p′-DDE and β-HCH. Furthermore, multiple linear regression analyses indicated that the age and educational levels of the pregnant women and their intake of fried/flamed food and shellfish were positively associated with β-HCH levels, and that the age and educational levels of the pregnant women and their intake of parity, beef, pork, mutton, and shrimp were positively associated with p, p′-DDE levels. This is the first study to investigate the exposure levels of pregnant women to PCBs and OCPs in Shanghai, and it should provide useful information for future related research.     

Association of polychlorinated biphenyls (PCBs) with live algae and total lipids in rivers-a field-based approach

The association of PCBs and live algal cells in rivers was studied at four locations during four seasons in two Wisconsin rivers. Positive relations between particle-associated PCBs and both chlorophyll-a and algal carbon concentrations indicated that live algal cells were a significant sorption phase for dissolved PCBs. Large Pennate diatoms (Navicula, Synedra, Pinnularia, Diatoma, and Cocconeis), or more rarely, Euglenoids (Trachelomonas sp.), dominated most sample assemblages on an algal carbon basis. These assemblages made up the highest percentage of total SOC during spring (average=50%) and lowest during summer (average=15%). At the three impounded sites, most individual PCB congeners were relatively enriched in samples characterized by: (1) high concentrations of algal carbon (as a percent of SOC), (2) algal assemblages dominated (or co-dominated) by Euglenoids, and (3) high concentrations of total lipids. Despite relatively higher masses of sorbed PCBs in the most lipid-rich samples, there was no robust correlation between total lipid content and particle-associated PCBs when aggregating all samples from the study. A possible explanation is that PCBs are associated with other structural components in live algae and (or) departure from chemical equilibrium in the river due to algal growth kinetics. A kinetic uptake model was used to calculate the mass of PCBs associated with the total organic carbon content of live algae. Based on this model, PCBs were enriched in algal cells during bloom seasons (spring and fall) compared to non-bloom seasons (summer and winter). Further, although individual PCB congener partition coefficients (log) to live algal cells (range=5.3-6.4) overlapped to those for detritus (range=3.6-7.4), PCBs tended to be enriched in detrital carbon pools during non-bloom conditions. The larger range of estimated PCB partition coefficients for detritus likely reflects the more heterogeneous nature of this material compared to live algal cells.     

Relative survival after exposure to polychlorinated biphenyls and dioxins: a follow-up of Japanese patients affected in the Yusho incident

Objectives

Little information is available on conditional survival among Yusho patients, who were accidentally exposed to PCBs and other dioxin-related compounds. In this study, we estimated relative survival among Yusho patients to quantify time trends in excess mortality compared to the general population.

Methods

A total of 1664 Yusho patients (860 males, and 804 females) were analyzed as Yusho cohort subjects. Relative survival ratio (RSR) was calculated as a measure of patient survival.

Results

Overall, 1-, 5-, 10-, and 15-year RSRs were 1.00 (95% confidence interval (CI): 0.99, 1.00), 1.00 (95% CI: 0.99, 1.01), 0.99 (95% CI: 0.98, 1.00), and 0.99 (95% CI: 0.98, 1.01), respectively. We did not observe meaningful increases or decreases in RSRs in either sex, which remained the same in all age groups for 1-, 5-, 10-, and 15-year RSRs.

Conclusions

This study provides quantitative evidence that Yusho patients have no significant difference in relative survival compared with the general Japanese population. Our results suggest that PCBs and dioxin exposure confers no excess mortality. This information may be important for both the clinical management of and patient coping with Yusho disease.     

Determination of dioxins and polychlorinated biphenyls in breast milk, maternal blood and cord blood from residents of Tohoku, Japan

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) are bioaccumulative chemicals that are considered to be toxic contaminants based on several epidemiological studies. To elucidate exposure levels of these chemicals in the present study, concentrations of PCDD/DFs, dioxin-like PCBs (DL-PCBs) and PCBs in breast milk, maternal blood and cord blood obtained from the same participants registered in a birth cohort study in Tohoku, Japan, were measured. Congener-specific analysis revealed several differences in minor congeners of these compounds among the three specimen types, although major congeners were detected in the specimens. The toxicity equivalence quantity concentrations (1998 WHO-TEF) and PCBs in breast milk, maternal blood and cord blood on the whole and on a lipid basis were in the order of breast milk > maternal blood > cord blood. Pearson's correlation coefficients of TEQs and total PCBs among the three specimens were high, with the correlation coefficient of TEQ between breast milk and maternal blood being the highest (r=0.94, p<0.001). On the other hand, the TEQ between breast milk and cord blood was the lowest (r=0.79, p<0.001). Pearson's correlation coefficient between the TEQ and PCBs in each specimen was also high (r=0.82-0.95, p<0.001). The associations of chemical concentrations with maternal age, parity, fish intake, BMI and the rate of body weight increase during pregnancy were analyzed with multiple linear regression analysis. TEQ concentrations and PCBs were negatively associated with parity (p<0.05), and maternal age was positively associated with PCBs (p<0.05). However, the associations with BMI and fish intake during pregnancy were not significant. These results suggest that parity is an important factor affecting the concentrations of dioxins and PCBs in these specimens.     

Levels of chlorinated pesticides and polychlorinated biphenyls in Norwegian breast milk (2002-2006), and factors that may predict the level of contamination

In the present study, polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were determined in 423 breast milk samples from women living in Norway. Various predictors for the contaminant levels were also investigated. The samples were collected in six counties, representing South, Central and North Norway in 2002-2006. Initial results showed significantly lower levels of OCPs in breast milk from ethnic Norwegians (N = 377) compared to ethnic non-Norwegians (N = 46). Median concentrations (range) of PCBs, p,p′-DDE, HCB, β-HCH and oxychlordane in breast milk of the Norwegian women, all parities included, were 103 (34-450), 41 (5.4-492), 11 (3.6-24), 4.7 (0.9-37) and 2.8 (0.5-16) ng/g lipid weight, respectively. Results indicated that sum of 18 PCBs, p,p′-DDE and β-HCH are good predictors for monitoring of PCB, DDT and HCH levels in Norwegian breast milk. Multivariable linear regression analyses showed that age was strongly associated with increasing OC levels (P < 0.001), whereas parity was associated with decreasing OC levels (P < 0.001). Smoking was associated with higher levels of PCBs, p,p′-DDE and β-HCH. The models explained from 17 to 35% of the variance. Median levels of OCs in the present Norwegian primparaes seemed to be 29-62% lower than corresponding results found in a Norwegian study from 2000-2002.     

Historical analysis of salmon-derived polychlorinated biphenyls (PCBs) in lake sediments

Several recent studies have highlighted the importance of salmon as a means to deliver biomagnifying contaminants to nursery lakes. There is a lack of studies, however, which demonstrate empirically how this source has varied through time. This is of great significance because past salmon-derived contaminant loading was potentially greater than it is today. By analyzing radiometrically dated sediment cores collected from ten lakes in Alaska and British Columbia (B.C.), we relate historical numbers of sockeye salmon spawners to ΣPCB concentrations and δ¹⁵N values (a paleolimnological proxy for past salmon-derived nitrogen) in the sediments. The results confirm that sockeye salmon have provided an important route for PCBs to enter the lakes in the past, a finding that is especially evident when the data of all lakes are pooled. Significant relationships between sockeye salmon numbers and δ¹⁵N, as well as ΣPCB concentrations and δ¹⁵N in sediments, were also found. However, it is difficult to establish relationships between salmon numbers, ΣPCBs and δ¹⁵N in individual lakes. This may be due to a number of factors which may influence contaminant loadings to the lakes. The factors include: a) changing salmon contaminant loads over time resulting from a lag in the upper ocean reservoir and/or changing salmon feeding locations; b) greater importance of atmospheric transport in lakes with relatively low salmon returns; and c) increased PCB scavenging due to higher algae productivity in the lakes in recent years.     

Enhanced removal of polychlorinated biphenyls from alfalfa rhizosphere soil in a field study: The impact of a rhizobial inoculum

Polychlorinated biphenyls (PCB) are persistent pollutants in soil environments where they continue to present considerable human health risks. Successful strategies to remediate contaminated soils are needed that are effective and of low cost. Bioremediation approaches that include the use of plants and microbial communities to promote degradation of PCB have significant potential but need further assessment under field conditions. The effects of growth of alfalfa (Medicago sativa L.) and inoculation with a symbiotic nitrogen fixing bacterium (Rhizobium meliloti) on the removal of polychlorinated biphenyls (PCB) from rhizosphere soil were evaluated in a field experiment. The initial PCB content of the soil ranged from 414 to 498 µg kg⁻¹. PCB removal for the rhizosphere soil was enhanced in the planted treatments, an average of 36% decrease in PCB levels compared to a 5.4% decrease in the unplanted soil, and further enhanced when plants were inoculated with the symbiotic Rhizobium (an average of 43% decrease) when evaluated at 90 days after planting. Plant biomass production was higher in the inoculated treatment. The total PCB content was increased from 3.30 µg kg⁻¹ to 26.72 µg kg⁻¹ in plant shoots, and from 115.07 µg kg⁻¹ to 142.23 µg kg⁻¹ in roots in the inoculated treatment compared to the planted treatment. Increased colony forming units (cfu) of total heterotrophic bacteria, biphenyl-degrading bacteria and fungi were observed in the rhizosphere of inoculated plants. PCB removal from the rhizosphere soil was not significantly correlated with the direct PCB uptake by the plants in any of the treatments but was significantly correlated with the stimulation of rhizosphere microflora. Changes in the soil microbial community structure in the planted and inoculated treatment were observed by profiling of bacterial ribosomal sequences. Some bacteria, such as Flavobacterium sp., may have contributed to the effective degradation of PCB and deserve further investigation.     

Polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in sediments from the Mersey Estuary, U.K

Sediments from the Mersey Estuary were analysed for polycylic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). Total PAH concentrations ranged from 626 to 3766 microg/kg and total PCB concentrations ranged from 36 to 1409 microg/kg. These concentrations are intermediate in comparison to other U.K estuaries with similar histories of industrialisation and urbanisation. The distribution of individual PAHs were consistent throughout the Mersey Estuary, this together with molecular indices suggests mainly pyrolitic inputs, augmented by a variety of industrial petrogenic sources. Comparison of tri-to-hepta PCB congeners revealed multiple sources and inputs throughout the estuary. A sediment core collected in close proximity to Garston Docks revealed the take-off, peak pollutant input and recent decline of PCB pollution. However, a second depth profile of sediments at Ellesmere Port showed little change in total or individual PCB concentrations due to extensive sediment reworking and mixing.     

Sedimentation of polychlorinated biphenyls (PCBs) in limnic and marine environments

The sedimentation rates of PCBs in two southern Swedish lakes and a coastal bay in the southern Baltic were determined using sediment traps. The rates were similar at the three locations and ranged from 1.2 to 10.9 μg PCBs m⁻² month⁻¹ during summer. The source for PCBs in sedimenting material is probably the atmosphere. PCB concentrations in sedimenting material were higher than those in surface sediment. This may be due to recirculation of sediment-bound PCBs.The reproducibility of collecting by sediment traps was examined by deploying duplicate traps simultaneously. There were no significant differences in PCB concentration of sedimenting material between traps placed in duplicate. Concentrations of PCBs in the different collecting vessel was similar within one trap.     

Background continental ozone levels in the rural U.S. southwest desert

From 1969 through 1978 an extensive ambient air quality monitoring program, including the measurement of atmospheric concentrations of ozone, has been conducted in a remote section of the desert in the southwestern U.S. Using a Monitor Labs chemiluminescent ozone instrument, these levels were measured atop a small mountain 500 feet above the valley floor of the Colorado River. During the winter months, when the prevailing low level winds are northerly in this river valley, rural continental background levels of ozone are attainable. From this continuous ozone data base, 13 of these representative high pressure periods have been selected for analysis. Results indicate a very distinct diurnal trend with an ozone minimum occurring from 0800–1000 hours Mountain Standard Time (MST) and an ozone maximum from 1600–1900 hours MST. Ozone concentrations range from a low of 19 ppb to a high of 44 ppb with the diurnal pattern exhibiting marked repeatability with respect to time of minima and maxima, seasonal changes and concentration levels.     

Distribution of polychlorinated biphenyls, organochlorine pesticides and polybrominated diphenyl ethers in human umbilical cord serum, maternal serum and milk from Wielkopolska region, Poland

The levels of organochlorinated pesticides (OCPs): p,p'-DDT and its metabolites, hexachlorobenzene (HCB), hexachlorocyclohexane isomers (HCHs), chlordanes and their metabolites, and 18 polychlorinated biphenyl (PCB) congeners were measured in maternal serum, umbilical cord serum and human milk collected from 22 mothers living in the Wielkopolska region, Poland. Additionally, 11 polybrominated diphenyl ether (PBDE) congeners were measured in the human milk samples. p,p'-DDT and its major metabolite, p,p'-DDE, together with HCB, were found in all milk and serum samples. Median concentrations of p,p'-DDE in maternal serum, umbilical cord serum and milk were 343, 329 and 634ng/g lipid weight (lw). PCB congeners 138, 153 and 180 were the major congeners measured in all serum samples, while CB 170 was detected in 74% and 100% of umbilical cord and maternal serum, respectively. Except for CBs 74, 101 and 105, which had a detection frequency of 77%, 23% and 82%, respectively, all investigated PCB congeners were measured in all human milk samples. The median concentrations of sum PCBs in maternal serum, umbilical cord serum and milk were 79, 60 and 133 ng/g lw, respectively. A good correlation (Spearman R(S)>0.75, p<0.001) was found for major PCBs, p,p'-DDT and p,p'-DDE, between maternal and umbilical cord serum, while the correlation was weaker between milk and serum. The median of sum PBDEs in human milk was 2.0 ng/g lw (range 0.8 to 8.4), with BDE 47 being always the most abundant PBDE congener and, together with BDE 153, being present in all samples. In general, results found in the investigated group are at the low end of the concentration range measured in Europe.     

Polybrominated diphenyl ethers and polychlorinated biphenyls in indoor dust in Durban,South Africa

Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) were measured in indoor dust of three microenvironments in Durban, South Africa. The sum of eight PBDEs and three PCBs were quantified by gas chromatography with mass spectral detection. The mean concentrations of ∑_n = 8 PBDEs and ∑_n = 3 PCBs in 10 homes, 11 offices, and 13 university students’ computer laboratories were 1710, 1520, and 818 ng/g, and 891, 923, and 1880 ng/g for PBDEs and PCBs, respectively. The concentration of PCBs found in homes was independent (P = 0.0625) of building construction year. Similarly, no relationship was observed between PCB concentrations and floor type. The concentrations of PBDEs correlated (r = 0.60) with PCB concentrations in homes, thus assuming similar sources. The elevated concentrations of PBDEs and PCBs may have significant implications for human exposure.     

Bioconcentration and redeposition of polychlorinated biphenyls by zebra mussels (Dreissena polymorpha) in the Hudson River

The potential impact of zebra mussel infestation on the dynamics of polychlorinated biphenyls (PCBs) in the Hudson River was determined by investigating the biodeposition and bioconcentration of PCBs, using algal food contaminated with 2,5,2'- and 2,4,2',4'-chlorobiphenyls (CBPs) in the laboratory. Approximately 46-90% of the total food was ingested depending on the supply rate. The highest proportion of ingested congeners was found in biodeposits (64+/-11% for 2,5,2'-CBP, and 52+/-6% for 2,4,2',4'-CBP), followed by tissues (17+/-3% for 2,5,2'-CBP, and 23+/-5% for 2,4,2',4'-CBP), and the lowest in shells. The clearance rate decreased with increasing food concentration, but increased with dilution rate. On the other hand, ingestion rate (IR) increased with food concentration and dilution rate. IR also increased with food supply rate (food concentrationxdilution rate) following the same linear function whether the supply rate was varied through food concentration or dilution rate. Therefore, the dilution rate- or food concentration-dependent variation in IR was due to the change in the food supply rate. IR was independent of the kind of PCB congeners. The trend of bioaccumulation in mussel tissues from food ingestion was similar to that of IR; bioaccumulation increased linearly with food supply rate, whether the supply rate was varied through the dilution rate or the food concentration. The bioaccumulation of 2,4,2',4'-CBP was significantly higher than that of 2,5,2'-CBP (p<0.05). The bioaccumulation was linearly related to the IR or to the total amount of food ingested. Assimilation efficiency, PCB incorporated in the tissue per total ingested PCB, was higher for 2,4,2',4'-CBP than for 2,5,2'-CBP (p<0.05). The congener concentration in biodeposits increased with food supply rate. However, the concentration of 2,5,2'-CBP was significantly greater than that of 2,4,2',4'-CBP in a mirror image of bioaccumulation. These results indicate that zebra mussels may significantly alter PCB dynamics in the Hudson River through redeposition from the water column and through bioconcentration.     

Bioaccumulation of polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in fishes from the Tittabawassee and Saginaw Rivers, Michigan, USA

Characterizing biological factors associated with species-specific accumulation of contaminants is one of the major focuses in ecotoxicology and environmental chemistry studies. In this study, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and non- and mono-ortho-substituted polychlorinated biphenyl (PCB) congeners were analyzed in various fish species from the Tittabawassee and Saginaw Rivers (12 fish species; n = 314 individuals), Michigan, USA. Due to their migratory habits, greater δ¹³C stable isotope values were found in walleye and white sucker among 12 fish species. Meanwhile, the δ¹⁵N values indicated that the trophic status was least in carp and greatest in largemouth bass. The greatest total concentrations of dioxins were found in fishes with the lowest trophic status (carp (n = 50) followed by channel catfish (n = 49)), and concentrations of ΣPCDD/Fs (20-440 pg/g ww (wet weight)), ΣPCBs (16-690 ng/g ww), and TEQs (6.8-350 pg/g ww) in carp were also greater than the least mean concentrations in other fishes. Contributions of various biological factors to the species accumulation were assessed. Body weight and lipid content were found to be the most significant factors influencing accumulation of ΣPCDD/Fs. Lipid content and trophic level seemed to be dominant factors determining accumulation of ΣPCB and TEQs, but negative correlations between trophic status and concentrations of ΣPCBs and TEQs were observed possibly due to the great concentrations in benthivorous fishes such as carp occupying lower trophic levels. These factors can be used to predict the contaminant levels of dioxins and health risks of the fishes in the river ecosystem.     

Seasonality of diffusive exchange of polychlorinated biphenyls and hexachlorobenzene across the air-sea interface of Kaohsiung Harbor, Taiwan

Gaseous and dissolved concentrations of polychlorinated biphenyls (PCBs) and hexachlorobenzene (HCB) were measured in the ambient air and water of Kaohsiung Harbor lagoon, Taiwan, from December 2003 to January 2005. During the rainy season (April to September), gaseous PCB and HCB concentrations were low due to both scavenging by precipitation and dilution by prevailing southwesterly winds blown from the atmosphere of the South China Sea. In contrast, trace precipitation and prevailing northeasterly winds during the dry season (October to March) resulted in higher gaseous PCB and HCB concentrations. Instantaneous air-water exchange fluxes of PCB homologues and HCB were calculated from 22 pairs of air and water samples from Kaohsiung Harbor lagoon. All net fluxes of PCB homologues and HCB in this study are from water to air (net volatilization). The highest net volatile flux observed was + 172 ng m^− 2 day^− 1 (dichlorobiphenyls) in December, 2003 due to the high wind speed and high dissolved concentration. The PCB homologues and HCB fluxes were significantly governed by dissolved concentrations in Kaohsiung Harbor lagoon. For low molecular weight PCBs (LMW PCBs), their fluxes were also significantly correlated with wind speed. The net PCB and HCB fluxes suggest that the annual sums of 69 PCBs and HCB measured in this study were mainly volatile (57.4 × 10³ and 28.3 × 10³ ng m^− 2 yr^− 1, respectively) and estimated yearly, 1.5 kg and 0.76 kg of PCBs and HCB were emitted from the harbor lagoon surface waters to the ambient atmosphere. The average tPCB flux in this study was about one-tenth of tPCB fluxes seen in New York Harbor and in the Delaware River, which are reported to be greatly impacted by PCBs.