Degradation of dibromophenols by UV irradiation

We examined the degradation of dibromophenols （DBPs）, i.e. 2,4-DBP, 2,6-DBP and 3,5-DBP by ultraviolet （UV） irradiation and estimated the relationship between degradability and molecular orbital properties of each dibromopbenol. The removal of DBPs under a UV lamp system was successfully performed in an aqueous solution. After 5 min of irradiation, the initial DBPs concentration of 20 mg/L was decreased to below 1 mg/L, and about 60% of bromide ion was released. A decrease in the concentration of dissolved organic carbon （DOC） suggested the mineralization of DBPs, The mineralization may occur after release of bromide ions because the decrease of DOC was slower than the release of bromide ions. The degradability of 3,5-DBP was slightly lower than 2,6-DBP and 2,4-DBE Molecular orbital calculation suggested that the electrophilic frontier density and the highest occupied molecular orbital （HOMO） energy may be related to the degradability of DBPs.     

Small queens and big-headed workers in a monomorphic ponerine ant

Evolution of caste is a central issue in the biology of social insects. Comparative studies on their morphology so far suggest the following three patterns: (1) a positive correlation between queen–worker size dimorphism and the divergence in reproductive ability between castes, (2) a negative correlation among workers between morphological diversity and reproductive ability, and (3) a positive correlation between queen–worker body shape difference and the diversity in worker morphology. We conducted morphological comparisons between castes in Pachycondyla luteipes, workers of which are monomorphic and lack their reproductive ability. Although the size distribution broadly overlapped, mean head width, head length, and scape length were significantly different between queens and workers. Conversely, in eye length, petiole width, and Weber’s length, the size differences were reversed. The allometries (head length/head width, scape length/head width, and Weber’s length/head width) were also significantly different between queens and workers. Morphological examinations showed that the body shape was different between queens and workers, and the head part of workers was disproportionately larger than that of queens. This pattern of queen–worker dimorphism is novel in ants with monomorphic workers and a clear exception to the last pattern. This study suggests that it is possible that the loss of individual-level selection, the lack of reproductive ability, influences morphological modification in ants.     

Levels and distribution of organochlorines in fish from Indonesia

Organochlorines such as PCBs, DDTs, HCHs, CHLs and HCB were determined in pooled whole body homogenized of fish samples collected from five locations during 1998 and 2003 in order to understand their contamination status, temporal and spatial variation in Indonesian waters. PCBs and DDTs were the predominant contaminants with concentrations from 9.7 to 2700 ng/g lipid wt. and 12 to 1100 ng/g lipid wt., respectively, while HCHs (nd-24 ng/g lipid wt.), CHL compounds (nd-81 ng/g lipid wt.) and HCB (0.22-28 ng/g lipid wt.) were one to two orders of magnitude lower. Among the locations, PCBs and CHLs were higher in the samples from highly industrialized and thickly populated-locations, whereas OC pesticides such as DDTs and HCHs were particularly more prominent in suburban and rural areas. Levels of OCs observed in the waters surrounding Java Island were higher than those in Sumatra Island, implying significant use of OCs in highly populated Java Island. Concentrations of PCBs and DDTs in fish from Jakarta Bay were significantly lower in the samples collected in 2003 as compared to fish in 1998, indicating decreasing trend of these compounds in the Indonesian environment. Recent estimated average daily intakes of PCBs (0.81 microg/person/day), DDTs (1.1 microg/person/day), HCHs (0.018 microg/person/day), CHLs (0.010 microg/person/day) were much lower than the threshold values recommended by various agencies, suggesting minimal risk of this compound via fish ingestion to Indonesians.     

Polybrominated diphenyl ethers and persistent organochlorines in Japanese human adipose tissues

The present study determined concentrations of polybrominated diphenyl ethers (PBDEs) and persistent organochlorines (OCs) in Japanese human adipose tissues collected during 2003–2004. Concentrations of PBDEs in adipose tissues were 1–2 orders of magnitude lower than those of OCs. However, observed PBDE congener levels in this study were relatively higher than those in Japanese human adipose tissues collected during 2000 reported previously, while OC levels were comparable to those in specimens collected during 1999 reported by our group. In addition, no age-dependent accumulation of PBDEs was observed, while OC levels except chlordane compounds increased with age. These results indicate recent human exposure to PBDEs in Japan. Among PBDE congeners accumulated in Japanese adipose tissues, BDE-153 was dominant, but this trend was different from those in human milk (BDE-47) and blood (BDE-209) reported previously in Japan, implying the congener-specific kinetics in human bodies. The significant positive correlations between PBDEs and OCs were observed in Japanese adipose tissues, indicating the similar exposure route of these contaminants for Japanese citizens, probably via fish intake.     

Possible change in Asian dust source suggested by atmospheric anthropogenic radionuclides during the 2000s

Decades-long monitoring of anthropogenic radionuclides in the atmospheric deposition in Tsukuba, Japan suggests not only the substantial impacts of the Asian dust (Kosa) on the deposition but also the possible change of the Kosa source region, especially during springs of the 2000s. In order to know more about such change, 4 single wet deposition events occurred in the spring of 2007 were scrutinized. The largest anthropogenic radionuclides wet deposition was supplied by the April 2–4 event. It brought several tens % of the monthly depositions (April 2007) of the dust (residue) mass (4.5 g m^?2) and anthropogenic radionulides (⁹⁰Sr: 16, ¹³⁷Cs: 97 and Pu: 3 mBq m^?2). None of the events observed fulfilled both criteria of the specific activities and ⁹⁰Sr/¹³⁷Cs activity ratio to the Tsukuba soil; they did not exhibit local soil dust signature. The Kosa events in fact have extensive impacts on the atmospheric environment over Japan in spring season. Considering the elevated specific activities as well as greater ¹³⁷Cs/⁹⁰Sr activity ratio in the deposited dust, it is hypothesized that the dust source areas in Asian continent would be shifting from the arid zone to the desert-steppe zone suffering from desertification during the 2000s. This type of the Kosa may be called as the ‘new-regime Kosa’. Chemical observation in the far downwind region of the Kosa dust could allow us to know possible shift in the source regions.     

The impact of cognitive aversion toward mercury on public attitude toward the construction of mercury wastes landfill site

Journal of Material Cycles and Waste Management - Minamata convention on mercury requests mercury wastes landfilling in environmentally safe manners. Owing to great difficulties to form public...