Polychlorinated dibenzo-p-dioxins and dibenzofurans in sediment, soil, fish, shellfish and crab samples from Tokyo Bay area, Japan

Concentrations of tetra- to octa-chlorinated dibenzo-p-dioxins and dibenzofurans in samples collected in or near Tokyo Bay, Japan, with a densely inhabited catchment area, were congener-specifically determined and discussed. Analyzed in this study were samples of surface sediment covering the whole bay area, reference soil representing atmospheric impact, and fish, shellfish and crab commonly consumed as food. The range of concentrations were comparable to or higher than those in other parts of Japan. The origins of these compounds in the catchment area of the bay were investigated in terms of homolog and isomeric compositions in the sediment samples. Biota-sediment accumulation factors for benthic species declined as the degree of chlorination increased.     

Atmospheric deposition of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and dioxin-like polychlorinated biphenyls in the Kanto Region, Japan

The atmospheric bulk (dry and wet) deposition of dioxins was investigated at four locations (Tokyo, Yokohama, Tsukuba, and Tanzawa) in the Kanto region (in Japan) over one year using a stainless-steel pot. Annual average polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/PCDF) deposition fluxes were estimated to be from 450 to 1300 ng/m2/yr, and the annual average TEQ fluxes from 5.7 to 17 ng-TEQ/m2/yr at the four locations. The PCDD/PCDF deposition flux was higher in winter than in summer. The deposition flux could be related to ambient temperature, particularly for less chlorinated PCDDs/PCDFs, while the deposition flux is not necessarily related to the amount of precipitation. The PCDD/PCDF deposition flux increased as the particle deposition flux increased, for the winter samples. Based on the ratio of the PCDD/PCDF deposition fluxes to the particle deposition fluxes, the contribution of the reentrainment of soil particles to the TEQ of PCDD/PCDF deposition was considered to be negligible in this region. Based on the air concentrations monitored near our deposition sampling points by the municipalities, the ratio of the annual deposition flux to the annual average air concentration was roughly estimated to be 0.082 cm/s. The range of deposition flux in the Kanto region was estimated to be from 1.5 to 31 (median: 9.8) ng-TEQ/m2/yr based on the range of air concentration data measured by the municipalities. The total annual deposition flux in the entire Kanto region was estimated to range from 50 to 900 g-TEQ/yr (median 320 g-TEQ/yr). This estimated flux was of the same order as the sum of estimated emissions from municipal solid waste incinerators and industrial waste incinerators in the Kanto region. The contributions of dioxin-like PCBs in Yokohama, Tsukuba, and Tanzawa depositions were less than 10% of the total TEQ; however, in Tokyo it was almost equal to or more than 50%.     

Dechlorination of 1,2,4-trichlorobenzene in the sediment of Ise Bay

The relation between dechlorination activities of 1,2,4-trichlorobenzene and anaerobic microbial activity were studied in the sediment collected at three sites in Ise Bay in Japan. The degradation rate of spiked 1,2,4-trichlorobenzene (3nmol ml⁻¹) ranged from 15 to 35 pmol day⁻¹ ml⁻¹ wet sediment and about 1/3 to 1/2 of degraded the trichlorobenzene was recovered as dechlorinated products. Among the dichlorobenzenes, the 1,2-isomer had the highest and 1,3-isomer had the lowest production rate. Comparing the three sampling sites, the trichlorobenzene degradation and dichlorobenzenes production rates were related to the sulfate reducing activity for the unit number of sulfate reducing bacteria. Production rates of dichlorobenzenes were completely inhibited by adding molybdate (20 mM), nitrate (60 mM), and formaldehyde solution (4 %). These results indicated that dechlorination activity in the Ise Bay sediment was supported by sulfate reduction activity in the sediment, and not supported by any other anaerobic microbial activity.     

Polychlorinated-dibenzo-p-dioxins, -dibenzofurans and -dioxin-like polychlorinated biphenyls in aquatic organisms from lake Kasumigaura,Japan

Polychlorinated-dibenzo-p-dioxins (PCDDs), -dibenzofurans (PCDFs) and -dioxin-like polychlorinated biphenyls (DLPCBs) were determined in aquatic wildlife of Kasumigaura Lake (KUL), Japan from 1978 to 2001. Two plankton species elucidated several fold greater concentrations (2400–7800) than small tiger fish (310–6500), shrimp (160–1100), and three large fish namely, black bass (120–240), carp (94–120) and mullet (54) on pg/g fat. PCDD homologues were predominant accumulants with >68–<95% contribution and remaining was shared by PCDFs. Accumulation, non-ortho DLPCBs in plankton (3500–9200), shrimp (1600–8600) and small fish (2000–8800) and large fish (1300–3900) on ng/g fat basis were several orders magnitude greater than PCDD/DFs. The mono-ortho DLPCBs in large fish species were 23?000–83?000?ng/g fat and which it is accounted 94.3–95.9% the total dioxin-like PCBs accumulation. Temporal trends of PCDDs, PCDFs, non-ortho PCBs and TEQ in shrimp and small tiger fish were varied. The mullet had minimum toxic equivalency “TEQ” (14?pg?TEQ/g) followed by plankton Neomysis intermedia (25?pg?TEQ/g), small tiger fish (mean: 33, ranges 14–66?pg?TEQ/g), plankton Cyclopus vicinus (34?pg?TEQ/g), carp (mean: 35, ranges 32–38?pg?TEQ/g), shrimp (mean: 38, ranges 11–68?pg?TEQ/g) and black bass (mean: 59, ranges 38–79?pg?TEQ/g) on fat basis. In all the samples, PCDD was predominant TEQ contributor followed by PCDFs and DLPCBs. The contribution of mono-ortho DLPCBs to the total TEQ was 0.52–0.92 in large fish.     

Optimal investment in sons and daughters when parents do not know the sex of their offspring

Optimal parental investment usually differs depending on the sex of the offspring. However, parents in most organisms cannot discriminate the sex of their young until those young are energetically independent. In a species with physical male–male competition, males are often larger and usually develop sexual ornaments, so male offspring are often more costly to produce. However, Onthophagus dung beetles (Coleoptera; Scarabaeidae) are highly dimorphic in secondary sexual characters, but sexually monomorphic in body size, despite strong male–male competition for mates. We demonstrate that because parents provide all resources required by their offspring before adulthood, O. atripennis exhibits no sexual size dimorphism irrespective of sexual selection pressure favoring sexual dimorphism. By constructing a graphic model with three fitness curves (for sons, daughters, and expected fitness return for parents), we demonstrate that natural selection favors parents that provide both sons and daughters with the optimal amount of investment for sons, which is far greater than that for daughters. This is because the cost of producing small sons, that are unable to compete for mates, is far greater than the cost of producing daughters that are larger than necessary. This theoretical prediction can explain sexual dimorphism without sexual size dimorphism, widely observed in species with crucial parental care such as dung beetles and leaf-rolling beetles, and may provide an insight into the enigmatic relationship between sexual size dimorphism and sexual dimorphism.     

Dynamics of PCDDs/DFs and coplanar-PCBs in an aquatic food chain of Tokyo Bay

Concentrations and accumulation profiles of PCDDs/DFs and coplanar-PCBs (co-PCBs) in aquatic biota (e.g., plankton, shellfish, benthic invertebrate, and fish) and sediment from Tokyo Bay were examined to elucidate the relationship between bioaccumulation and trophic level in the food web as determined by the stable nitrogen isotope analysis. Bioaccumulation patterns of PCDDs/DFs and co-PCBs varied greatly among congeners. Accumulation patterns of PCDDs/DFs and co-PCBs are not solely explained by their physicochemical properties. Biota-sediment accumulation factors (BSAFs) for co-PCBs in biota from Tokyo Bay were significantly greater than those of PCDDs/DFs. Furthermore, the slopes of the plots of delta15N and BSAF values and water solubility of 2,3,7,8-substituted PCDDs/DFs and co-PCBs were highly correlated. The results of our study would provide the valuable information to understand the accumulation properties of PCDDs/DFs and co-PCBs that can be used as a scientific basis to determine the sediment quality criteria of PCDDs/DFs and co-PCBs.     

Chlorinated persistent organic pollutants in black-tailed gulls (Larus crassirostris) from Hokkaido, Japan

Concentrations and patterns of several chlorinated persistent organic pollutants (POPs) including polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) and DDTs, HCHs, CHLs and HCB were determined in black-tailed gulls (Larus crassirostris) from breeding grounds in Hokkaido, Japan. Subcutaneous fat of five adult gulls was analyzed, which had different concentrations of target compounds, whereas gull eggs contained similar concentrations of target compounds. Similar congener profiles were found between adult gulls and eggs. The concentrations of non-ortho PCBs varied from 3.4 to 13.5 ng/g lipid weight (lw) in the fat of black-tailed gulls and from 2.4 to 7.4 ng/g lw in their eggs. 2,3,7,8-PCDD/Fs occurred at relatively lower concentrations than non-ortho PCB congeners in both adult gulls and eggs. The total TEQs (toxic equivalents, PCDD/Fs+ non-ortho PCB) ranged from 0.26 to 1.0 ng/g lw in adult gulls and ranged from 0.19 to 0.58 ng/g lw in eggs.     

Estimation of effects of dioxins and dioxin-like PCBs on wildlife population--a case study on common cormorant

We presented a method for quantitatively evaluating the effects of chemical pollutants in the environment on a wildlife population. We expressed the effects of exposure to dioxins and dioxin-like PCBs in Tokyo Bay sediment on a common cormorant (Phalacrocorax carbo) population in two ways. One was the changes in the intrinsic growth rate, and the other was the changes in the gross population size. The effects of exposure to the compounds were estimated by using the method of population ecology and available field data. Common cormorant population at Shinobazu Pond in Tokyo, Japan during 1974-1986 was selected as the target population. Intrinsic growth rate or gross size of the population based on the calculated residual level of dioxins and dioxin-like PCBs in the period was estimated to decrease to 89% or 85% of that without exposure to the compounds, respectively.     

Evaluation of an ecosystem model in ecological risk assessment of chemicals

We used a Lake Suwa version of Comprehensive Aquatic Systems Model (CASM_SUWA) to demonstrate the risk estimation of 10 different chemicals and examined the applicability and reliability of the model in ecological risk assessment by qualitatively and quantitatively comparing with the results of studies on multiple species using mesocosm tests. The qualitative comparison of the model results with those of the reported mesocosm tests indicated that some evidence observed in mesocosm studies supported the indirect effects predicted from simulation using the model. The comparison of the concentration levels at which 20% biomass reduction (BR20) in the most sensitive population estimated from the model with the no-observed effect concentration values derived from multiple species mesocosm tests (MS-NOEC) suggested that both data were related to each other and the model can be used to help in the determination of an ecological acceptable level of chemicals in aquatic environments. The analysis of the potential of indirect effects of a chemical for fish population indicated that the magnitude of the potential of indirect effects was quantified based on the ratio of BR50 to LC50 for fish population.     

Long-term measurement of volatile organic compounds in ambient air by canister-based one-week sampling method

A canister-based 1 week sampling method using a mechanical flow controller and a 6 L fused-silica-lined canister was evaluated for the long-term measurement of 47 VOCs in ambient air at pptv (volume/volume) to ppbv levels by use of a three-stage preconcentation method followed by GC-MS analysis. The GC conditions were initially optimized for complete separations of several pptv-level VOCs (e.g. vinyl chloride, 1,3-butadiene, acrylonitrile, 1,2-dichloroethane and chloroform) in ambient air because the selected ions are easily interfered with by coexisting C4-, C5-hydrocarbons and analytes presented at ppbv levels. Thirty-four VOCs determined by the 1 week and 24 h sampling method in December 16-22 (2002) had concentrations of 6.0-15000 pptv per compound. Concentrations of 28 VOCs (including polar VOCs (e.g. methyl isobutyl ketone and butyl acetate)) obtained by the method were approximately equal to the mean values calculated from 24 h sampling (< +/- 10% deviation). Six VOCs that had low concentrations of 6.0-43 pptv showed more than +/- 10% deviation. Thirteen VOCs were not detected during the entire sampling period. The effect of relative humidity or ozone for the specific VOCs (e.g. MIBK, butyl acetate, vinyl chloride, 1,3-butadiene and styrene) was negligible.