Detection of Dechlorane Plus and brominated flame retardants in marketed fish in Japan

Fish samples purchased from Japanese markets were analyzed for Dechlorane Plus (DP)(syn-, anti-), polybrominated diphenyl ether (PBDE), and hexabromocyclododecane (HBCD)(α, γ). Twenty fish were analyzed using gas chromatography-mass spectrometry for DP and PBDE, and using liquid chromatography-tandem mass spectrometry for HBCD. DP was detected in 18 samples and ∑DP concentrations were <0.2-14.2 pg g⁻¹ wet wt. Among the DP isomers, anti-DP was the dominant residue observed in this study. PBDE was detected in all samples. Concentrations of ∑PBDE ranged from 2.2 to 878 pg g⁻¹ wet wt. HBCD was detected in 18 samples, and ∑HBCD concentrations were <0.02-21.9 ng g⁻¹ wet wt. In fish landed near the East China Sea and the Sea of Japan, we detected relatively high concentrations of DP, PBDE, and HBCD. These results indicate that the seawaters around East Asia are contaminated with flame retardants. This study demonstrates the presence of DP in fish marketed in Japan for the first time.     

Contributions of humic substances to the dissolved organic carbon pool in wetlands from different climates

Wetlands are an important source of DOM. However, the quantity and quality of wetlands' DOM from various climatic regions have not been studied comprehensively. The relationship between the concentrations of DOM (DOC), humic substances (HS) and non-humic substances (NHS) in wetland associated sloughs, streams and rivers, in cool temperate (Hokkaido, Japan), sub-tropical (Florida, USA), and tropical (Sarawak, Malaysia) regions was investigated. The DOC ranged from 1.0 to 15.6 mg CL(-1) in Hokkaido, 6.0-24.4 mg CL(-1) in Florida, and 18.9-75.3 mg CL(-1) in Sarawak, respectively. The relationship between DOC and HS concentrations for the whole sample set was regressed to a primary function with y-intercept of zero (P<0.005) and a slope value of 0.841. A similar correlation was observed between DOC and NHS concentrations, with a smaller slope value of 0.159. However, the correlation coefficient of the latter was much larger when the data was regressed to a logarithmic curve. These observations suggest the presence of a general tendency that the increased DOC in the river waters was mainly due to the increased supply of HS from wetland soils, whereas the rate of the increase in the NHS supply has an upper limit which may be controlled by primary productivity.