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”，但目前对沿海地区这一潜在温室气体的估计和未来预测，特别是针对溶解氧水平较低和氮输入增加的情况，充其量只是一个近似值。 来自南加州大学和伍兹霍尔海洋研究所的科学家计划通过确定两个沿海地点（德国瓦登海的叙尔特和加州沿海泻湖的圣卡塔利纳岛）的N2O动态来改善这些值。 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，结合沉积物和孔隙水分析。 一些沉积物芯收集将受到上覆水的氧含量和硝酸盐浓度的变化，以确定氮循环活动和N2O通量作为低氧或硝酸盐添加的函数的变化。 使用实验培养，N2O，硝酸盐和氨的同位素组成将被测量，以提供净同位素通量和N2O循环过程的定量估计。 微剖面分析和多同位素方法的结合使用不仅将提供对这些地点N2O产生和通量的详细了解，而且还将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：该研究将加强与德国科学家的合作。 提议者计划创建一个网页，讨论他们项目中使用的技术，以及他们实地考察期间发生的活动。 南加州大学的一名博士后和一名本科生将得到支持和培训，作为该项目的一部分。

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.