Collaborative Research: Nitrous Oxide Production and Fluxes in Coastal Sediments: Response to Environmental Change

虽然海洋沉积物是已知的一氧化二氮（N2O）产生和排放的“热点”，但目前对这种来自沿海地区的强效温室气体的估计和未来的预测，特别是在溶解氧水平降低和氮输入增加的情况下，充其量只是近似值。南加州大学和伍兹霍尔海洋研究所的科学家们计划通过测定两个沿海地点——德国瓦登海的锡尔特岛和加利福尼亚沿海泻湖的圣卡塔利娜岛——的N2O动态来改进这些值。为了实现他们的目标，他们将进行现场，高分辨率的微传感器测量N2O，氧气，硝酸盐，一氧化氮，硫化氢，pH值，氧化还原电位和温度，并结合沉积物和孔隙水分析。收集的一些沉积物岩心将受到上覆水中氧含量和硝酸盐浓度变化的影响，以确定氮循环活性和N2O通量作为低氧或硝酸盐添加的函数的变化。利用实验孵育，将测量N2O、硝酸盐和氨的同位素组成，以提供净同位素通量和N2O循环过程的定量估计。结合使用微剖面和多同位素方法，不仅可以详细了解这些地点的N2O生产和通量，还可以为最近开发的代谢模型提供数据，以模拟和预测不同环境条件下的N2O动态。更广泛的影响：这项研究将加强与德国科学家的合作。支持者计划创建一个网页，讨论他们项目中使用的技术，以及他们在实地考察期间进行的活动。来自南加州大学的一名博士后和一名本科生将作为该项目的一部分得到支持和培训。

Although marine sediments are known "hotspots" of nitrous oxide (N2O) production and emission, current estimates and future projections of this potent greenhouse gas from coastal areas, especially in response to lower levels of dissolved oxygen and increased nitrogen inputs, are an approximation at best. Scientists from the University of Southern California and Woods Hole Oceanographic Institute plan to improve upon these values by determining N2O dynamics at two coastal sites, Sylt, the German Wadden Sea, and Santa Catalina Island, a California Coastal lagoon. To attain their goal, they will carry out in-situ, high resolution microsensor measurements of N2O, oxygen, nitrate, nitric oxide, hydrogen sulfide, pH, redox potential, and temperature in conjunction with sediment and pore water analyses. Some of the sediment cores to be collected will be subjected to changes in oxygen content and nitrate concentrations in the overlying water to determine changes in nitrogen cycling activity and N2O flux as a function of low oxygen or nitrate addition. Using experimental incubations, the isotopic composition of N2O, nitrate, and ammonia will be measured to provide a quantitative estimate of net isotopic flux and N2O cycling processes. The combined use of microprofiling and multi-isotope approaches will provide not only detailed insight into N2O production and flux at these sites, but also yield data for a recently developed metabolic model to simulate and predict N2O dynamics under varying environmental conditions.Broader Impacts: The research would strengthen the collaboration with German scientists. The proponents plan to create a webpage to discuss the technologies used in their project, as well as the activities taking place during their field trips. One postdoc and one undergraduate student from the University of Southern California would be supported and trained as part of this project.