東亞季風與地形效應對大氣塑膠微粒沉降之影響

Microplastics Deposition under Interplay of Asian Monsoon and Landscape

李易哲(Yi-Jhe Lee)

指導教授 ： 黃誌川

國立臺灣大學/理學院/地理環境資源學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202101940

摘要

塑膠汙染對自然環境有很大的影響，但對於大氣塑膠微粒的沉降速率尚有很大的空白亟需填補。本研究於陽明山國家公園，架設14個雨水採樣站於兩條東北季風所經剖線，透過每雙週一次的雨水採樣探討大氣塑膠微粒沉降速率。結果指出塑膠微粒的沉降量約為每天每平方公尺158片至1178片，由尺寸小於73μm的微粒為主要組成。顆粒、碎片以及纖維狀之塑膠微粒占比分別為48, 34及18%。將各測站依其空間分布分為城市端、山頂、近海洋及海洋側的測站。搭配上逆軌跡模式(Back trajectory model)的氣團追蹤，夏季時氣團源自南海沿著台灣南部北上，塑膠微粒由本地人為活動供給至大氣環境，搭配午後雷陣雨沉降至地面，沉降速率無明顯空間差異，大約為240個/m2/天，粒徑平均大小為64 μm。當東北季風盛行以後，粒徑淘選能力下降，粒徑大小增為78 μm，迎風面塑膠微粒沉降量較背風面之城市端測站多出60%，地形淘選之效果在此期間效果卓越，透過統計檢定發現城市與山頂測站之粒徑分布並無顯著差異。此研究提供證據證實臺灣的空氣中存在塑膠微粒，平均而言每天每平方公尺會落下304±216顆塑膠微粒，且確認大氣塑膠微粒的研究，應納入東亞季風的影響。

關鍵字

陽明山 ； 東亞季風 ； 長程傳輸 ； 尼羅紅染劑

並列摘要

Although plastic pollution is ubiquitous in the natural environment, the atmospheric microplastic (MPs) deposition remains a large gap need to clarify. In this study, we installed 14 collectors in two transects of Yangmingshan National Park, where was influence by the northeast monsoon airflow. By analyzing the rainfall sample, with a sampling frequency of every two weeks, atmospheric MPs deposition rate was estimated. The number of MPs in atmospheric deposition samples, ranged from 158 to 1178 n/m2/day, with the main size less than 73 μm. Particles, fragments and fibers constituted 48, 34, 18% of the total MPs, respectively. Based on the spatial distribution, sampling sites were classified into city, mountain divide, near ocean and ocean. Back-trajectory model indicated that air mass was originated from the South China sea in summer. Local human activity may contribute fresh MPs (the mean MPs size: 64μm) to atmosphere and deposited via thundershower, accounted for about 240 n/m2/day. When northeast monsoon was prevailing, the ability of size-selection for wind was decreasing and thus the mean MPs size increased to 78μm. MPs deposition rate in the ocean sites were more than city sites by 60%. Landscape had an outstanding performance on MPs size-selection in this period, no significant difference in size distribution was observed between city and mountain. This study provides an evidence of airborne MPs exist in Taiwan air, with an average of 304±216 n/m2/day and confirms airborne MPs research should include the northeast monsoon influence.

並列關鍵字

Yangmingshan ； Northeast monsoon ； long-range transport ； Nile red

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