Collaborative Research: Role of Atmospheric Nitrogen Deposition in Estuarine and Coastal Production and Food Chain Dynamics

大气沉积，如降雨和干降，是一种 生物可利用氮日益重要的来源 在河口和沿海地区：约占其总量的30%， 氮负荷来自大气来源。 氮从 大气沉积可能是氮的独特来源， 沿海沃茨，因为可能发生直接的地表水沉积 河口营养物剥离区下游， 陆源氮负荷占绝大部分。 此外，分析 研究表明，溶解的有机物可以是 总溶解氮的重要部分， 来自大陆和海洋的降水。 这 降雨中的氮素已被证明能刺激初级 在邻近北卡罗来纳州的沿海沃茨生产。 影响 大气氮沉降将阐明评估 藻类的初级生产力和营养反应， 生物测定和稳定同位素示踪剂测量 丰度水平。 雨水中氮的三个来源 （硝酸盐，铵和溶解有机氮）将被 随后进入具有稳定同位素的初级生产者， 监测物种组成和光合速率。 的 将初级产品从藻类转移到微生物和 浮游动物种群将被测定，以调查 放牧和微生物循环的反应， 生产力 氮素的定量模型与收支 进入该地区的大气沉降将是最后的 研究的结果。 结果可能对全球建模者有用 试图评估大气沉积物对 气候和物种多样性。

Atmospheric deposition, as rainfall and dryfall, is an increasingly important source of biologically-utilizable nitrogen in estuarine and coastal regions: about 30% of their combined nitrogen loading comes from atmospheric sources. Nitrogen from atmospheric deposition may be a unique source of nitrogen in coastal waters, as direct surface water deposition may occur downstream of estuarine nutrient stripping zones that assimilate the majority of terrigenous nitrogen loading. Moreover, analyses of rainwater reveals that dissolved organic matter can be a significant fraction of the total dissolved nitrogen in precipitation from both continental and oceanic origins. This nitrogen from rainfall has been shown to stimulate primary production in coastal waters adjacent to North Carolina. Impacts of atmospheric nitrogen deposition will be elucidated by assessing algal primary production and trophic responses with complementary bioassays and stable isotope tracers measurements at the natural abundance level. The three sources of nitrogen in rainwater (nitrate, ammonium, and dissolved organic nitrogen) will be followed into primary producers with stable isotopes, while species composition and photosynthetic rates are monitored. The transfer of primary products from algae to both microbial and zooplankton populations will be assayed to investigate the response of grazing and the microbial loop to increased productivity. A quantitative model and budget of nitrogen entering the area from atmospheric deposition will be the final result of the study. Results may be useful to global modelers attempting to assess the importance of atmospheric deposition on climate and species diversity.