探討塑膠微粒之豐度與分布概況：以臺北盆地河流系統為例

Abstract

近年大眾對於塑膠微粒汙染議題之關注日漸提升，然目前相關的文章多以海洋污染為研究對象，鮮少提及塑膠微粒對淡水系統之影響及汙染。亞洲國家每年由河流系統排放近120萬噸的塑膠廢料注入海洋，因此被認定為主要塑膠廢料產生區。台北市政府近年來致力於塑膠回收改革，目前已達55%的廢棄物回收率，但每年仍有25,400噸的塑膠由淡水河排放至台灣海峽。 本研究之目的為探討塑膠微粒（直徑0.3-5 mm）於台北盆地河流系統的豐度及分布變化。在臺北盆地內，大漢溪、新店溪及基隆河往北匯流至淡水河，並注入台灣海峽。本研究利用蒐集網於各支流末端進行採樣。結果顯示在基隆河、新店溪、大漢溪及淡水河的塑膠微粒之最高含量分別為64.37、 70.52、 83.70及13.84 個/立方公尺，本研究進而推斷，自淡水河表面至水深15公分之範圍，每年所輸出的塑膠微粒含量可達104.35噸。塑膠微粒之豐度與河流流速呈現反向變化。另外，塑膠微粒豐度於強降雨時增加。作為量化河川系統塑膠微粒汙染程度之首例，本研究將可提供台灣未來進行塑膠微粒研究分析之參考。

The presence of microplastic has been a growing concern in recent years. In spite of the increasing interest in microplastic, the majority of studies have focused on the existence of microplastic in marine environments, while little emphasis placed on freshwater systems. With an estimate of over 1.2 million tonnes of plastic entering the oceans annually via rivers, Asian countries are listed as the main producers of mismanaged plastic waste. The city of Taipei, with its 55% recycling rate and plastic reforms is estimated to discharge up to 25.4 thousand tonnes of plastic into the Taiwan Strait annually. This research presents a case study of establishing the abundance and distribution of microplastic (in the size range of 0.3 - 5 mm) flowing through the rivers of the Taipei Basin into the Taiwan Strait. The Taipei Basin is comprised of three large tributaries: Dahan, Xindian, and Keelung River, which merge into Tamsui River. Using a manta trawl, sampling was performed at the mouth of each tributary. Results show highest microplastic concentrations in Keelung River, Xindian, Dahan River, and Tamsui River to be 64.37, 70.52, 83.70, and 13.84 particles/m3, respectively. Extrapolated annual values yield an output of 127.19 tonnes of microplastic just within the top 15 cm of the Tamsui River. Spatial variation showed inverse relationship between concentration of microplastic and discharge rates. Aside from microplastic flux across all river profiles, temporal variations were also detected. Increase of microplastic was observed during the onset of heavy precipitation. Being the first to quantify the presence of microplastic in the Taipei Basin, this study will help to setting a baseline for future microplastic research.