2017-07-012024-05-14https://scholars.lib.ntu.edu.tw/handle/123456789/661709摘要：哈伯法製銨(1918年，諾貝爾化學獎)開啟了大量的氮肥應用(主要為溶解性無機氮, dissolved inorganic nitrogen, DIN)。影響所及，不僅造成陸域水體的優氧化、近海死區的擴張，也導致了許多陸域生態系因氮飽和所產生的生物多樣性滅絕，被視為比全球增溫更重大的環境挑戰。此議題，在人口密集的東亞地區尤為嚴重。因此，本研究目的為：利用集水區尺度的分析來探討東亞地區氮循環的過程。具體而言，是希望瞭解類似氣候不同土地利用環境下，大陸型與島嶼型流域的氮循環過程之異同。擬進行全流域的活性氮物種濃度與同位素時空分佈監測、進行氮轉化與移除速率的定量，並嘗試建立兩類流域氮循環的生地化模型，評估模式運用到其他流域的可行性，以提升對於區域尺度或全球尺度流域氮通量估算與預測的能力。<br> Abstract: Since Haber-Bosch method proposed, human activities had dramatically increased the amount of nitrogen in terrestrial ecosystems which altered nitrogen cycling significantly. In fact, the excess nitrogen (originated from artificial fertilizer, population growth, and cultivation of legumes) caused the substantial risks to terrestrial and river ecosystems. Furthermore, the excess nitrogen transported by rivers to coastal zones would result in the loss of seagrass, decrease of biodiversity and increase of harmful algae blooms. Those specific threats highlight the importance of DIN (dissolved inorganic nitrogen) transport from watersheds. However, the nitrogen transport processes within watersheds in subtropical zones were poorly understood. The main barriers maybe attributed to the lack of highly-frequent observations, and the unknown sources (from precipitation or soil water or groundwater). Besides, the transport processes, such as flowpaths and subsurface transit time, which control the nitrogen movement, are also poorly discussed. In this proposal, we propose a 3-yr proposal aims to determine the hydrological controls in DIN transport in continental and high-standing catchments. The Jiu-long catchment in China and Feitsui reservoir catchment in Taiwan were selected as study area. The concentrations and fluxes of DIN in rainfall, soil water, and streamwater with other geochemical parameters are sampled and the high-frequency sampling will be conducted during extreme events. Based on the comprehensive dataset, the DIN budget for the two catchments can be the baseline for interpolating the regional estimates. As for the transport processes, advancing the understanding in flowpaths and subsurface transit time in catchment scale can aid us in interpreting the nitrogen cycling. This study is not only useful for land management, but also for improving the accuracy of DIN export in region and global scale.溶解性無機氮優養化大陸型流域島嶼型流域Dissolved inorganic nitrogeneutrophicationcontinental watershedsmall mountainous rivers