琵琶湖・淀川流域における環境水中の全有機フッ素および構成ペルフルオロ化合類の存在実態

Abstract

環境水中での有機フッ素化合物類の存在実態の把握を主目的とし，2016年8~10月に琵琶湖・淀川流域の68地点の環境水を対象に，15種 PFCs，15種 PFCs 生成ポテンシャル（PFC-FPs），全有機フッ素（TOF）を分析した．その結果，1）TOF濃度が67地点で検出下限（32 ng-F/L）以上で検出され，琵琶湖・淀川流域の濃度分布データが得られた．2）15種 PFCs濃度がTOF濃度に占める比率は下水処理水，河川水，湖水による顕著な差はなく全試料の平均値で22%であった．3）琵琶湖・淀川流域のTOF濃度は下水処理水，河川水，湖水の順に高く（各平均値748, 458, 175 ng-F/L），安威川流域のN下水処理場で115, 000 ng-F/Lであったことから，特定汚染源からの負荷が示された．4）N下水処理場下流のTOFとPFC-FPs負荷量は，水量が47倍の淀川下流に対し各々2.2倍（30, 700 g/日）, 3.2倍（8, 800 g/日）となり，未知のPFCs関連物質の負荷が示唆された．Main objective of this study was to understand the occurences of total organic fluorine (TOF), the component perfluorinated compounds (PFCs) and their formation potentials (PFC-FPs) in the Lake Biwa – Yodo river basin. Total of 68 water samples (9 lake water samples, 45 river water samples and 9 wastewater treatment plant (WWTP) effluents) were collected during August to October 2016. TOF was analyzed by Combustion Ion Chromatography and PFCs and PFC-FPs were analyzed by LC-MS/MS. As a result, 1) TOF concentrations in 67 samples were detected at more than limit of detection (32 ng-F/L). 2) The ratios of ∑15 PFCs in TOF concentration were not significantly different among each water sample type (lake water, river water and WWTP effluent) and average value was 22%. 3) TOF concentrations were detected higher in the order of WWTP effluent, river water and lake water on average (748, 458, 175 ng-F/L, respectively) in the Lake Biwa – Yodo River basin while it was detected at 115, 138 ng-F/L in effluent from a single WWTP (N-WWTP) in the Ai river basin, suggesting that there was a specific point source. 4) TOF and PFC-FPs loading from N-WWTP were calculated as 30, 740 g/day and 8, 807 g/day respectively, which were 2.2 and 3.2 times higher than the loading at the downstream of Yodo river where the flowing water flux was 47 times higher. It was suggested that unknown PFCs relatives were discharged from N-WWTP.