Monitoring and modeling of water and related nutrient fluxes in rice-based cropping systems

为了更好地了解控制水稻系统碳、氮通量的生物和水文过程，人们进行了许多研究。但很少有研究试图明确地将田间尺度上养分运输的水文和生物地球化学控制联系起来。在这项研究项目中，我们的目的是提高我们对不同水稻种植制度储存和释放水分和养分的过程的理解。流域模型框架(CMF)将与生物地球化学MOBILE-DNDC模型(SP6)相耦合，以模拟(1)水、C和N的垂直和横向传输过程和(2)预测依赖于种植制度的水储存和净化、气体调节、养分循环和食物供应等生态系统服务的反应。SP7遵循拒绝主义框架，其中模型复杂性根据可用数据和过程理解进行调整。最先进的分析仪器将连接到一个独特的自动采样系统，首次在现场连续测量水的同位素组成以及溶解的碳和氮溶质。要取样的水包括地表水、灌溉水、地下水和水蒸气。将使用腔衰荡光谱测量2H/H和18O/16O。同位素特征将允许估计水的平均通过时间，在蒸发和蒸腾之间进行分配，并分离流动路径。将安装配备流通池的高光谱紫外光度计，以连续测量硝酸盐和DOC。

Many studies have been conducted with the aim to better understand biologic and hydrologic processes that control C and N fluxes in rice paddy systems. But rarely have studies attempted to explicitly link the hydrological and biogeochemical controls of nutrient transport on the field scale. In this research project we aim to improve our understanding of processes that are involved in storing and releasing water and nutrients of different rice-based cropping systems. The Catchment Modeling Framework (CMF) will be coupled to the biogeochemical MOBILE-DNDC model (SP6) in to simulate (1) vertical and lateral transport processes of water, C and N and (2) to predict the reaction of ecosystem services such as water storage and purification, gas regulation, nutrient cycling and food supply in dependence of cropping systems. SP7 follows a rejectionist framework where model complexity is adapted to available data and process understanding. State-of-the-art analytical instruments will be connected to a unique automatic sampling system to continuously measure water isotopic composition as well as dissolved carbon and nitrogen solutes in situ for the first time. Waters to be sampled include surface water, irrigation water, groundwater and water vapor. Cavity Ringdown Spectroscopy will be used to measure 2H/H and 18O/16O. Isotopic signatures will allow estimating water mean transit times, partitioning between evaporation and transpiration and separating flow paths. Hyperspectral UV photometers equipped with a flow-through cell will be installed for continuous measurements of nitrate and DOC.