Development of a method for measurement of a time-weighted average concentration of polycyclic mutagens in marine environment-for practiced utilization in monitoring of marine environment.

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(1) Results of measuring the time-weighted average (TWA) concentration of Benzo (a) pyrene (BaP) in the Seto Inland Sea, Japan.The values of the TWA concentration of BaP from 1999 to 2000 ranged from 0.16 to 8.77 ng/L for the sampling sites in Okayama seashore, from 0.08 to 7.04 ng/L for Osaka Bay sites and from undetectable level (0.01 ng/L) to 18.88 ng/L for the sites in Northern Kyushu.(2) Effects of water temperature on the decrease in weight of plaster balls.We gave a dissolving test by hanging a plaster ball in moving water and found that the decrease in weight of the plaster ball correlated well with water flow intensity, and the regression coefficient and the intercept of regression line were affected by water temperature. We obtained the following equation :C={ΔW-(0.1232T+0.2247)}/(0.0189T+0.8162)where C is water flow intensity (cm/sec), ΔW is the decrease in weight of plaster ball (g) and T is water temperature (℃) and Therefore, according to this equation, it becomes possibl … More e to correct the value of measured TWA if water temperature is known.(3) Preserving condition of blue rayon after hanging and the recovery rate of BaP.One nanogram of BaP was dissolved in distilled water in a beaker and let BaP adsorbed to BR.We then calculated the recovery rate from amount of BaP after keeping it under various conditions against the initial one that was obtained from extraction without preservation. They were 101.6±8.2% (for one week) and 100.0±6.8% (for two weeks) when BR was preserved with aluminium-foil-wrapping at -5℃, and 93.5±5.1% (for four weeks) when preserved with transparent-plastic-foil-wrapping at 15-2O℃. The amount of the BaP adsorbed to BR has maintained over 90% even in the room temperature. Our study provides a convenient and a practical procedure for long-distance transportation of the samples.(4) Relationship between the amount of BaP and mutagenicity in samples after BR hanging.We have reported that mutagenicity detected by fhe BR hanging technique positively correlated with the amount of BaP.The present study unexpectedly found some samples despite of small amount of BaP showed high mutagenicity. Most of these phenomena were observed on the samples hanging in estuaries of the rivers flowing through the cities. This fact suggests that the city sewages might contain highly mutagenic substances except for BaP.(5) Publications and presentation of the study.We have published and presented the study results in scientific journals and at some conferences (see references). Furthermore, we are preparing for presentations at following international symposiums in order to receive various evaluations from foreign scientists : (1) PRIMO11 (July 2001, Plymouth, UK), (2) ISTA10 (August 2001, Quebec, Canada), (3) 8thICEM (October 2001, Shizuoka, Japan). Less