CAREER: Linked Hydrologic and Atmospheric Fluxes from Riparian Biogeochemical Hotspots

河岸地区被认为是生物地球化学的“热点”，那里的生物地球化学反应和大气排放加剧。需要新的监测和建模战略，以发展对发生在陆地-水界面上的通量和转变的基于过程的理解。本研究的重点是应用微气象方法的新技术，在陆气相互作用和流域水文学的子学科之间建立桥梁。这些结果将有助于约束河岸热点地区生物地球化学过程的速率和时间，并更好地确定水文因素在控制这些通量中的作用。该项目将特别关注流域中氮和汞循环的案例。在施用氮基肥料的农业地区，可能会产生大量的一氧化二氮（N2O）排放。一氧化二氮是一种强有力的温室气体，与大气臭氧的破坏有关。河岸地区被假设为N2O排放的热点，因为高水平的硝酸盐和溶解有机碳的混合。可调谐二极管激光痕量气体分析仪将测量沿海河岸沼泽的N2O通量，在那里也将监测溪流排放和地下水化学。流域水文模型将与基于过程的一氧化二氮生成模型相结合，以解释和扩大观测结果。由于大气沉积的影响，即使在偏远地区，地表水中的汞浓度也很高。这项研究将检验河岸地区通过与水文运输和化学转化相关的相互作用时间尺度来控制河流汞浓度的理论。将结合水汞浓度和溪流排放，在高地河岸湿地的点和景观尺度上测量汞排放。相互作用的时间尺度对河流汞浓度的影响将评估瞬时排放对汞通量的影响。这项研究将与弗吉尼亚海岸保护区LTER站点的校园LTER项目联系起来，来自附近北安普顿县高中的学生将参加夏季研究项目。环境科学II类的流域模块将开发与学生正在进行的水质监测程序接口。弗吉尼亚大学的本科生将通过独立学习和杰出的专业论文，以及参加实地方法和数据分析课程来参与这项研究。本研究涉及博士生的培养，他们将在开展实地工作和建模活动时发挥积极的指导作用。这项工作将吸引一系列学生参与多学科研究和新兴技术的应用。

Riparian areas are considered to be biogeochemical "hotspots", where biogeochemical reactions and atmospheric emissions are heightened. New monitoring and modeling strategies are needed to develop a process-based understanding of the fluxes and transformations that take place across the terrestrial-aquatic interface. This research centers on applying new technology with micrometeorological methods to bridge the sub-disciplines of land-atmosphere interaction and watershed hydrology. The results will help constrain the rate and timing of biogeochemical processes in riparian hotspots and better define the role of hydrological factors in controlling these fluxes. In particular, this project will focus on cases of nitrogen and mercury cycling in watersheds.In agricultural areas where nitrogen-based fertilizers are applied, significant emissions of nitrous oxide (N2O) can occur. N2O is a potent greenhouse gas that has been implicated in the breakdown of atmospheric ozone. Riparian areas are hypothesized to be hotspots of N2O emissions due to the mixing of high levels of nitrate and dissolved organic carbon. A tunable diode laser trace gas analyzer will measure N2O fluxes in a coastal riparian marsh, where stream discharge and groundwater chemistry will also be monitored. A watershed hydrological model will be integrated with a process-based model of N2O production to interpret and scale up the observations.Mercury concentrations in surface water have been found to be high in even remote locations due to effects of atmospheric deposition. This research will test the theory that riparian areas control stream water mercury concentrations through interacting timescales associated with hydrological transport and chemical transformations. Mercury emissions will be measured, at both point and landscape scales, in an upland riparian wetland in conjunction with aqueous mercury concentrations and stream discharge. The effect of interacting timescales on stream water mercury concentrations will evaluate the impact of transient discharge on mercury fluxes.This research will link with the Schoolyard LTER program at the Virginia Coastal Reserve LTER site, where students from nearby Northampton County High School will take part on summer research projects. A watershed module for the Environmental Science II class will be developed to interface with the students' ongoing water quality monitoring program. University of Virginia undergraduates will take part in this research, through both independent study and distinguished major theses, and through participation in a Field Methods and Data Analysis class. This research involves the training of Ph.D. students, who will have active mentoring roles while carrying out field work and modeling activities. This work will engage a range of students in multi-disciplinary research and in the application of emerging technology.