残留性化学物質がどのようにして表層水に侵入するのか(How a persistent chemical enters our surface waters)

2026-01-06  スイス連邦材料試験研究所(EMPA)

Empaは、スイス連邦環境庁(FOEN)およびベルン大学と共同で、PFASの中で最小分子であるトリフルオロ酢酸(TFA)が大気中で生成され、降水を通じて水環境へ移行する過程を解析した。3年間の降水・表流水測定、1984年以降の保存水試料、詳細な大気モデルを組み合わせた結果、TFAの環境放出量は近年急増し、今後も増加が続くと示された。主因は冷媒・噴射剤として使用が拡大するHFOの分解であり、生成されたTFAは分解されにくく、雨により河川・地下水へ移行して最終的に海洋へ蓄積する。農薬由来の直接流入も重要な供給源である。モデルは観測値の約3分の2を説明でき、未知の前駆物質の存在が示唆された。TFAの長期毒性は未解明だが、極めて持続的で除去困難なため、前駆物質の使用抑制など予防的対応が求められる。

残留性化学物質がどのようにして表層水に侵入するのか(How a persistent chemical enters our surface waters)
TFA is the smallest molecule in the PFAS family. (black: carbon, red: oxygen, white: hydrogen, blue: fluorine) Graphic: Adobe Stock.

<関連情報>

スイスの降水および表層水中のトリフルオロ酢酸(TFA):傾向、発生源の特定、予算 Trifluoroacetate (TFA) in precipitation and surface waters in Switzerland: trends, source attribution, and budget

Stephan Henne, Florian R. Storck, Henry Wöhrnschimmel, Markus Leuenberger, Martin K. Vollmer, and Stefan Reimann
Atmospheric Chemistry and Physics  Published:16 Dec 2025
DOI:https://doi.org/10.5194/acp-25-18157-2025

Abstract

Sources and budgets of the persistent, anthropogenic compound trifluoroacetate (TFA) are poorly quantified across different environmental media. Recently, the introduction of hydrofluoroolefins and the continued use of other fluorinated compounds has increased environmental levels of TFA. Here, we present concentrations of TFA observed in precipitation and surface waters in Switzerland during three years of continuous monitoring and in archived water samples, collected since 1984. Mean observed TFA concentrations ranged from 0.30 to 0.96 µg L−1 across 14 precipitation sites and from 0.33 to 0.88 µg L−1 across 9 river sites in 2021–2023 – a four-to-six-fold increase since 1996/1997. Simulated atmospheric degradation of known TFA precursors accounted for 63 % (58 %–70 %) of the observed deposition (48 % (41 %–54 %) hydrofluoroolefins and 15 % (12 %–18 %) long-lived fluorinated gases; mean and range across sites) for sites on the Swiss Plateau. In Switzerland, atmospheric (wet+dry) deposition of TFA amounted to 24.5 ± 9.6 Mg yr−1, whereas TFA terrestrial inputs from the degradation of plant protection products (PPP) in soils, estimated from the literature, ranged from 2.9 to 11.8 Mg yr−1, depending on the assumption on degradation efficiency. TFA inputs from the degradation of PPP dominated 2–3 times over atmospheric deposition in Swiss croplands. These inputs were balanced by exports through the major rivers, 31 ± 4 Mg yr−1. Archived precipitation samples from the period 1986 to 2020 revealed that TFA was formed in the atmosphere before the introduction of known atmospheric precursors, whereas in the 1990s TFA deposition increased along with their concentrations. However, simulated atmospheric degradation underestimates summertime TFA deposition five-fold. Continued use of fluorinated compounds is likely to enhance TFA deposition in the future. Additional environmental monitoring and source attribution studies are paramount for refining the assessment of TFA sources and levels for potential health and environmental risks.

1102水質管理
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