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年度	113	專案性質	實驗性質
專案類別	研究專案	研究主題	調查
申請機構	中央研究院	申請系所	環境變遷研究中心
專案主持人	李承軒	職等/職稱	助研究員
專案中文名稱	利用總可氧化前驅物檢驗法探討河川底泥中被低估的全氟與多氟化合物
中文關鍵字	新興關切汙染物, 前驅物, 全氟物質, 沉積物, 淡水河
專案英文名稱	Using the Total Oxidizable Precursor Assay to Explore Underestimated Per- and Polyfluoroalkyl Substances in Riverine Sediments
英文關鍵字	Contaminants of emerging concern, Precursor, PFAS, sediment, Danshui River
執行金額
執行期間	2024/12/1 至 2025/11/30
計畫中文摘要	本研究於2025年三月（枯水期）與七月（豐水期）前往淡水河流域進行河川底泥採樣，目的是為了初步探討淡水河底泥中全氟與多氟烷基物質（Per- and Polyfluoroalkyl Substances, PFAS）的空間分布，同時，本研究採用總可氧化前驅物檢驗法（Total Oxidizable Precursor Assay, TOP assay），將非標的PFAS前驅物轉化為可檢測的PFAS，藉此初探隱藏於底泥中的PFAS前驅物們。常規的PFAS分析結果顯示，淡水河底泥中可檢測出約40種PFAS，包含C4至C16的全氟羧酸、C4至C10的全氟磺酸與多種前驅物，例如全氟磺醯胺、全氟烷磺醯氟基PFAS與，多氟調聚物羧酸/磺酸。即便在基隆河與新店溪上游區域也仍然可檢測出部分PFAS，顯示出PFAS的分布極為廣泛；底泥中高濃度PFAS多半出現在淡水河主流江子翠至關渡一帶，以及基隆河、新店溪與大漢溪下游匯流河段，表示人為活動可能造成大量的PFAS輸入。此外，淡水河感潮河段強烈的海淡水混合作用，可能也會藉由顆粒的凝聚作用，將河水中的PFAS帶入底泥沉積物中。平均來說，三月份底泥樣本中的PFAS濃度高於七月份，可能和豐水期時的河川流量較大有關。經過TOP assay處理後的底泥，PFCA的濃度顯著地提升，常規分析可見之PFAS前驅物皆變成未檢出，加上每個樣品內部添加的13C8-PFOSA同位素氧化指示劑降解率>99%，顯示有添加足夠的氧化劑生成自由基去降解PFAS前驅物。被轉化生成的PFCA在下游區域增加的濃度百分比皆大於100%，部分PFCA甚至可達1000%-10000%，而透過莫爾反應比例計算PFCA的質量平衡，可檢測之標的PFAS前驅物僅能貢獻少量的PFCA生成，絕大部分的PFCA皆來自於未知的PFAS前驅物，此結果強烈暗示有著高濃度的PFAS前驅物也一同沉積於底泥中，而這些PFAS前驅物無法被常規的目標分析所檢測並定量，導致大大地低估淡水河底泥中的PFAS真實濃度。本研究證明了淡水河流域受到人為活動影響，底泥中存在著多樣化的PFAS化合物，此結果提供了第一手的背景濃度供相關但為參考，未來將會有助於建構底泥中PFAS污染暴露與健康風險評估。最後，本研究展現出TOP assay可以作為一項簡易的篩選工具，透過量測PFCA來判別潛在PFAS前驅物的多寡，從而再決定使否要進一步使用其他工具做後續的探討。能夠適切地評估或知曉潛在PFAS前驅物在底泥中的污染程度，也將有助於進行後續的環境管理與補救措施。
計畫英文摘要	In this study, we investigated the spatial distribution of per- and polyfluoroalkyl substances (PFAS) in the sediments collected from the Tamsui River tributary during March 2025 and July 2025. In addition to the regular PFAS monitoring, the Total Oxidizable Precursor Assay (TOP assay) was employed to convert non-target PFAS precursors into detectable PFAS, thereby providing an initial exploration of the hidden PFAS precursors within the sediments. Regular PFAS analysis revealed that approximately 40 PFAS were detected in the sediments, including perfluorocarboxylic acids (C4–C16 PFCA), perfluorosulfonic acids (C4–C10 PFSA), and various precursors such as perfluorosulfonamides (FASA), perfluoroalkanesulfonyl fluorides (PASF-based PFAS), and polyfluorinated polyether carboxylic/sulfonic acids (FTCA/FTS). Detectable PFAS were found even in the upstream of Keelung River and Xindian River, indicating ubiquitous PFAS distribution. High PFAS concentrations were mainly observed in the mainstem of Tamsui River, as well as in the downstream confluence zones of Keelung, Xindian, and Dahan Rivers, suggesting that anthropogenic activities may have led to substantial PFAS inputs. Moreover, the strong mixing of seawater and freshwater in the Tamsui River estuary could promote particle aggregation processes that transfer PFAS from the water column into the sediment. On average, PFAS concentrations in March sediments were higher than those in July, likely due to greater river discharge during the wet season. After TOP assay, the concentrations of PFCAs increased significantly, while previously detectable PFAS precursors became undetectable. In addition, the percent degradation of the spiked oxidation indicator (¹³C₈-PFOSA) exceeded 99%, confirming that sufficient oxidants were added to generate radicals capable of degrading PFAS precursors. The increase in PFCA concentrations in downstream areas exceeded 100%, with some PFCAs rising by 1,000–10,000%. Molar mass balance indicated that known target PFAS precursors could only account for a small portion of the newly formed PFCAs, implying that most of the produced PFCAs originated from unknown PFAS precursors. This strongly suggests the co-occurrence of high levels of unidentified PFAS precursors in the sediments, which cannot be captured by conventional target analysis, causing a significant underestimation of the true PFAS burden in Tamsui River sediments. This study demonstrates that the Tamsui River watershed is strongly influenced by anthropogenic activities and that its sediments contain diverse PFAS. Our results provide valuable baseline data for future assessments of PFAS contamination, exposure, and health risks associated with riverine sediments. Finally, the study highlights that the TOP assay can serve as a simple screening tool to estimate the abundance of potential PFAS precursors by measuring PFCA, thus aiding decisions on whether further analytical methods are required. A proper understanding of the extent of PFAS precursor contamination in sediments will be beneficial to subsequent environmental management and remediation efforts.