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105/10/18 14:00 臺灣大學地理環境資源學系黃誌川副教授 演講
演講公告
張貼人：網站管理員 ╱ 公告日期：2016-10-14演 講 公 告
主講人：黃誌川 副教授
地點：中央大學科學一館S-325教室
摘要：
講題：Characteristics of Riverine DIN Export in Subtropical High-standing Island, Taiwan
主講人：黃誌川 副教授
臺灣大學地理環境資源學系
時間：10月18日（星期二）下午2點
地點：中央大學科學一館S-325教室
摘要：
Increases in nitrogen (N) availability and mobility resulting from anthropogenic activities has substantially altered nitrogen cycle both locally and globally. Taiwan characterized by the subtropical montane landscape with abundant rainfall, downwind to the most rapidly industrializing east coast of China can be a demonstration site for extreme high N input and riverine DIN (dissolved inorganic N) export. We used 49 watersheds with similar climatic and landscape settings, but classified into low-, moderate-, and highly-disturbed categories based on population density to illustrate their differences in nitrogen inputs through atmospheric N deposition, synthetic fertilizer and human emission and DIN export ratios. Our results showed that the island-wide average riverine DIN export is ~3800 kg-N/km2yr, approximately 18-fold higher than the global average mostly due to the large input of synthetic fertilizer. The average riverine DIN export ratio is 0.30-0.51, which is much higher than the average of 0.20-0.25 of large rivers around the world indicating excessive N input relative to ecosystem demand or retention capacity. The low-disturbed watersheds despite of high input only export 0.06-0.18 of the input and well buffered to changes in input quantity suggesting high efficiency of nitrogen usage or high N retention capacity of the less disturbed watersheds. The moderate-disturbed watersheds show a linear increase of output with increases in total N inputs and a mean DIN export ratio of 0.20 to 0.31. The main differences in land use between low and moderately disturbed watershed are the relative proportions of agricultural land and forests, not the built-up lands. The export ratio of the highly-disturbed watersheds is 0.42-0.53, which is very high and suggests that much of the N input is transported downstream. The increases in riverine DIN export ratio along with the gradient of human disturbance in subtropical Taiwan shows a gradient in excess N saturation. Our results help to understand factors controlling riverine DIN export and provide a sound basis for N emissions/pollution control.
最後修改時間：2016-10-14 AM 9:30
