REU: Interactions Between Gas and Solute Exchange and Path-ways of Porewater Turnover in Intermittently Flooded Wetlands

间歇性淹水湿地沉积物中的氧气交换、水流入、蒸散和排水之间的相互作用，最终控制着这些生态系统的大部分生产力和结构，人们对此知之甚少。这些过程将在几个沼泽区(Creekbank，Low&Amp；在大西佩维塞特盐沼、马萨诸塞州经过充分研究的淡水芦荟沼泽、弗吉尼亚沼泽、不常被淹的盐沼以及将控制洪水和排水制度(新泽西州)的地块中，这些现场实验将与蒸渗仪和植物室内的平行实验室实验相结合。通过对几种湿地类型的几种淹水模式的研究，结果将有助于确定水周转-气体交换相互作用的共性，这些过程构成了多种类型的间歇淹水湿地生态系统。气体交换将通过它们所受的年度、月球、每日和潮汐循环来测量这些系统中与地下水位漂移有关的气体交换。将用天然气体(O2、CO2、CH4)和示踪气体(Ne、C2F6、C2H6)测量通量，并分配植物和沉积物表面的气体交换通量。将蒸散造成的水损失与排水损失进行比较，并测量洪水、雨水和地下水取代水的情况。将直接测量排水、蒸散量和Creekbank沉积物的总水分损失，并确定植物生物量、沉积物类型和蟹穴对排水的影响。将确定大米草的间隙盐度和硫化物浓度、蒸散速率、排盐性和根氧状况之间的关系。将测量湿地沉积物通过植物内的运输以及排水和表面交换造成的溶质损失。使用多学科方法对气体交换-沉积物物理之间的相互作用进行详细的调查将在两个质量中进行。和弗吉尼亚沼泽。这些实验还将作为现有湿地水文技术的相互校准。这个项目的研究团队经验丰富，能力很强。所有实地考察地点都提供了极好的研究机会。可用的设施对这项任务来说绰绰有余。

Interactions between oxygen exchange, water influx, evapotranspiration and drainage in sediments of intermittently flooded wetlands which ultimately control much of the productivity and structure of these ecosystems are poorly understood. These processes will be studied in: Several marsh zones (creekbank, low & high marsh) across the natural flooding- frequency gradient in Great Sippewissett Salt Marsh, a well studied freshwater Phragmites marsh in Mass., a Virginia marsh, an infrequently flooded salt marsh and plots where the flooding and drainage regime (NJ) will be controlled: These field experiments will be coupled with parallel laboratory experiments in lysimeters and plant chambers. By studying several flooding regimes in several wetland types, the results will allow determination of the generality of water turnover-gas exchange interactions as processes structuring many types of intermittently flooded wetland ecosystems. Gas exchange will be measured in relation to water table excursions in these systems through the annual, lunar, daily and tidal cycles to which they are subject. Fluxes will be measured with both natural (O2, CO2, CH4) and tracer (Ne, C2F6,C2H6) gases and partition gas exchange between plants and sediment surface fluxes. The water loss due to evapotranspiration will be compared to drainage losses, and water replacement by flood water, rain and groundwater will be measured. Direct measurements will be made of drainage, evapotranspiration and total water loss from creekbank sediments and determine the effects of plant biomass, sediment type and crab burrows upon drainage. Relationships of interstitial salinity and sulfide concentration, evapotranspiration rates, salt exclusion and root oxygen status in Spartina will be determined. The solute losses from the wetland sediments by transport within the plants and by drainage and surface exchange will be measured. Detailed investigation of the interaction between gas exchange-sediment physics using a multidisciplinary approach will be conducted in both a Mass. and Virginia marsh. These experiments will also serve as an intercalibration of existing wetland hydrologic techniques. The research team for this project is well experienced and capable. All field sites offer excellent opportunities for research. Facilities available are more than sufficient to the task.