| 摘要: | 全球對環境中微型塑膠污染的關注日益增加。在不同生態環境中，甚至在人類活動較少的地方，都已發現微型塑膠的存在。各種生物體內和人體器官中均檢測出微型塑膠，飲用水和食品中也不例外。微型塑膠因具有較高的比表面積，容易吸附環境中的污染物，生物攝入後，這些污染物可能在體內脫附，影響健康，而這些生物最終可能又被人類攝入，形成污染物在食物鏈中的傳遞和放大效應。
目前台灣對上游集水區到下游飲用水處理廠(Drinking Water Treatment Plant，DWTP)中的微型塑膠污染研究有限，環境中微型塑膠相關研究也相對不足。因此本研究為台灣首篇完整調查上游集水區到下游飲用水處理系統中微型塑膠污染的研究，自2023年8月至2024年6月，於石門水庫及其下游DWTP進行微型塑膠之採樣調查，水庫共採樣五次，而DWTP共採樣三次。樣品以芬頓法和密度分離法對表層水樣進行前處理，以尼羅紅染色法輔助識別微型塑膠，最後再以μ-Raman光譜儀進行聚合物種類的鑑定。主要深入調查桃園石門水庫的水體，包括表層水和中層水，以及位於下游的飲用水廠各處理單元對微型塑膠的去除效率，並以聚合物風險指數、污染負荷指數、污染風險指數評估水體中微型塑膠污染的程度。
研究結果顯示，所有採樣點均受到微型塑膠污染，並且表層水和中層水中的微型塑膠豐度分別為4.53 ± 2.3 items/L和4.12 ± 1.86 items/L。在微型塑膠尺寸分佈方面，小於 300 μm的微型塑膠佔比超過80%，形狀分佈上，各採樣點的微型塑膠主要為碎片占70%以上。石門水庫中的主要聚合物類型是PP、PE和PET，水庫PRI為最高污染風險等級(V)，到最低污染程度等級(I)，整體而言，石門水庫的微型塑膠污染程度較輕微。在DWTP中沉澱池去除效率最高，可達63%；快濾池去除效率最低，僅11%；清水池的去除效率為46%。整體微型塑膠的去除效率達到83%，DWTP內除了原水採樣點為最高污染風險等級(V)外，其餘採樣點的污染程度均為最低等級(I)，說明DWTP在去除污染物和微型塑膠的效果顯著。統計分析顯示，水庫微型塑膠豐度與採樣日前72小時累積降雨量有顯著正相關。降雨被認為是微型塑膠豐度增加的重要原因。微型塑膠豐度也受到地表特徵所影響，曲流地形間微型塑膠豐度發現了顯著差異(p < 0.05)。;Global concern about microplastic pollution is increasing, with microplastics detected in various environments, including remote areas with minimal human activity. These particles have been found in organisms, human organs, drinking water, and food. Due to their high surface area, microplastics can adsorb environmental pollutants, which may impact health upon ingestion and can transfer up the food chain.
This study represents the first comprehensive investigation of microplastic pollution from upstream catchment areas to downstream drinking water treatment plants (DWTP) in Taiwan. Conducted from August 2023 to June 2024, the research involved collecting microplastic samples from Shimen Reservoir and its downstream DWTP. The reservoir was sampled five times over the study period, while the DWTP was sampled three times. Surface water samples were pre-treated using the Fenton method and density separation, identified with Nile Red staining, and analyzed with μ-Raman spectroscopy. The study assessed microplastic pollution levels in surface and intermediate waters of the reservoir, and evaluated the removal efficiency of various DWTP treatment units using the Hazard Index (H), Pollution Load Index (PLI), and Pollution Risk Index (PRI).
Results revealed microplastic pollution at all sampling points, with surface and intermediate water concentrations of 4.53 ± 2.3 items/L and 4.12 ± 1.86 items/L, respectively. The majority of microplastics were in the 37~300 μm size range, and fragments constituted over 70% of the samples. The primary polymers identified were PP, PE, and PET. The PRI varied from the highest (V) to the lowest (I) pollution levels, with Shimen Reservoir exhibiting relatively minor pollution. In the DWTP, the sedimentation basin demonstrated the highest removal efficiency at 63%, whereas the rapid filtration had the lowest at 11%, and the treated water achieved 46%. Overall, the DWTP reached an 83% removal efficiency, with all sampling points, except raw water, showing the lowest pollution level (I), indicating effective microplastic removal. Statistical analysis indicated a significant positive correlation between microplastic levels and rainfall in the 72 hours preceding sampling, suggesting that rainfall is a major factor influencing microplastic abundance. Additionally, microplastic levels varied significantly with meandering terrain (p < 0.05). |
