湖の健全性を保つための新しい除草剤の長期影響を初検証（RPI collaborates on first-of-its-kind research study to keep New York lakes healthy）

2025-10-21 レンセラー工科大学（RPI）

レンセラー工科大学（RPI）は、ニューヨーク州の湖沼における新規水生除草剤「フロルピラウキシフェン・ベンジル（ProcellaCOR）」の長期的環境影響を初めて調査した。EPAと州環境保全局により承認され、外来種ホザキイトモを駆除する目的で30以上の湖で使用されている。本研究では、処理後数日で水中から薬剤が消失する一方、湖底堆積物には1年以上残留し、時間とともに深部へ移動することを確認。また湖水循環により処理区域外へ拡散する現象も観測された。これにより、実環境では実験室試験と異なる挙動を示すことが明らかになり、現地調査の重要性が強調された。研究はRPIのダリン淡水研究所（DFWI）とIBM、Lake George Associationの共同プロジェクト「The Jefferson Project」の一環で実施。研究者らは今後もProcellaCORの堆積物・植物・動物への影響を追跡し、湖沼生態系保全に資する科学的知見を提供する方針である。

＜関連情報＞

ヨーロッパミズヒキを防除するために大規模な貧栄養湖に散布されたフロルピラウキシフェンベンジルの堆積物中の残留 Persistence of florpyrauxifen-benzyl in sediments following application to a large oligotrophic lake to control Eurasian watermilfoil

B. Wiltse, B. Mattes, C. Navitsky, S. Chakraborty, J.C. Stager, E. Buell, K.C. Rose
bioRxiv Posted: September 25, 2025
DOI:https://doi.org/10.1101/2025.09.23.678083

Abstract

Florpyrauxifen-benzyl (FPB) is a recently registered arylpicolinate herbicide used to control dicots including Eurasian watermilfoil (EWM). Laboratory studies indicate rapid degradation of FPB in water, but sediment persistence in aquatic systems remains poorly understood, creating uncertainty in ecological risk assessments. We evaluated the environmental fate and transport of FPB and its degradants in water, plants, and sediment following application of the herbicide to two bays of Lake George, NY. FPB was rapidly lost from the water column within 72 hours, consistent with prior studies, but persisted in sediments for at least one year. Sediment cores revealed vertical migration of FPB, which may contribute to frequent non-detects in surface sediments and potentially explain why US EPA was unable to establish sediment half-lives in aquatic systems. Measured concentrations exceeded the 28-day no observable adverse effect concentration (NOAEC) for chironomids for at least a year, highlighting the potential for long-term chronic exposure to benthic organisms. Modeled sorption and dilution scenarios aligned with field observations and indicated that circulation dynamics expanded the affected area beyond the direct treatment zones. These results demonstrate that FPB and its degradants persist longer in sediments than suggested by laboratory studies, raising important questions about long-term ecological risks, effects of repeated applications, and underestimation of sediment persistence. Long-term studies such as this are essential for understanding the fate of these compounds and for guiding informed decisions about future herbicide applications.