下水放出後の化学汚染が100倍以上増加(Chemical pollution increases more than 100-fold after sewage discharges)

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2025-04-07 インペリアル・カレッジ・ロンドン

英国の南部沿岸に位置するチチェスター港とラングストーン港で、汚水の排出後に化学汚染が100倍以上増加することが研究で明らかになりました。ブリュネル大学ロンドン校、ポーツマス大学、インペリアル・カレッジ・ロンドンの環境科学者たちは、市民科学者グループ「クリーン・ハーバーズ・パートナーシップ」と協力し、2022年の春と秋に339のサンプルを収集・分析しました。その結果、67種類の医薬品、29種類の農薬、9種類の違法薬物を含む105種類の化学物質が検出され、特に雨天時の下水道のオーバーフロー(CSO)による排出後に濃度が急上昇することが確認されました。これらの化学物質は水生生物に高いリスクをもたらす可能性があり、特にペット用のノミ・ダニ駆除剤として使用されるイミダクロプリドが懸念されています。研究者たちは、これらの化学物質の環境への長期的な影響を理解するために、さらなる調査と包括的なモニタリングの必要性を強調しています。

<関連情報>

合流式下水道越流の影響を受けた海洋保護港における表層水と生物相の化学的プロファイリング Chemical profiling of surface water and biota in protected marine harbours impacted by combined sewer overflows

Jasmin Uhlhorn, Keng Tiong Ng, Leon P. Barron, Alex T. Ford  Thomas H. Miller
Environment International  Available online: 7 April 2025
DOI:https://doi.org/10.1016/j.envint.2025.109417

Graphical abstract

下水放出後の化学汚染が100倍以上増加(Chemical pollution increases more than 100-fold after sewage discharges)

Highlights

  • 105 contaminants detected: 67 pharmaceuticals, 29 pesticides & 9 recreational drugs.
  • Concentrations of chemicals increased during autumn following increased rainfall.
  • CSO discharges were an important source for loading of specific chemicals.
  • The highest risk was associated with the neonicotinoid, imidacloprid.
  • Seaweed showed the highest cumulative chemical burden reaching up to 343 ± 71 ng g−1.

Abstract

Few studies exist that focus on contaminants of emerging concern (CECs) in transitional and coastal waterbodies. This study presents chemical profiling of two protected marine harbours on the South coast of the UK sampled in 2022. Across 21 sites, 105 unique compounds were detected (0.05 ng L-1 ––1798 ng L-1, median: 11 ng L-1) in water samples and biota, including 67 pharmaceuticals, 29 pesticides and nine recreational drugs. There were significant differences between campaigns with increased chemical numbers and concentrations that coincided with increased rainfall and combined sewer overflow (CSO) discharges. The comparison with CSO discharges revealed that they were an important source for loading of specific chemicals with concentrations increasing for some cases by three-orders of magnitude. High relative risks were estimated for sites sampled during recorded CSO discharges for five compounds with risk quotients (RQs) ranging from 1.1 up to 9.3, with the highest risk from the neonicotinoid, imidacloprid. To understand the exposure in biota, six species; one macroalgae (Fucus vesiculosus) and five fauna (Hediste diversicolor, Patella vulgate, Crassostrea gigas, Carcinus maenas, Echinogammarus marinus) were analysed (n = 5/species) at a CSO-impacted site. Between eight to 18 compounds were detected with Fucus vesiculosus (seaweed) showing the highest accumulation with mean cumulative burdens reaching up to 343 ± 71 ng g−1. Surface water contamination did not correlate with body burdens. Overall, the work highlights the complexity of the chemical space present in a transitional waterbody showing dynamic contamination patterns that are further influenced by tide, rainfall and salinity. CSOs demonstrated an important but compound specific role for CEC input and pulsing into receiving waters.

1102水質管理
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