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Phosphorus Dynamics in Flooded Wetlands: I. Model Development and Sensitivity Analysis
Citation:
Hantush, M., L. Kalin, S. Isik, AND A. Yucekaya. Phosphorus Dynamics in Flooded Wetlands: I. Model Development and Sensitivity Analysis. Presented at 2012 World Environment & Water Resources Congress, Albuquerque, NM, May 20 - 24, 2012.
Impact/Purpose:
To present a comprehensive, relatively simple process-based model for phosphorus retention and cycling in natural wetlands.
Description:
Wetlands are unique ecosystems that are recognized as a transition between terrestrial and aquatic ecosystems. Wetlands provide habitats that support wildlife and biodiversity and act as natural purifiers for sediment and nutrient laden runoff from upland regions. They receive, hold and recycle nutients continually washed from urban and agricultural areas. In this effort we present a comprehensive, relatively simple process-based model for phosphorus retention and cycling in natural wetlands. The model partitions a flooded wetland ecosystem into two basic layers, the water column and bottom soil/sediment layers. The soil layer is further partitioned into aerobic and anaerobic layers. The model accounts for various chemical, biological and physiological processes, which control transport and fate of phosphorus in each compartment. In addition to physical transport processes of advection, mixing, sedimentation/resuspension, diffusion and burial, the model couples oxygen dynamics to phosphorus related chemical processes. In particular, the model considers adsorption of phosphate and phosphorus removal from solution by precipitation under aerobic conditions, and releases of phosphorus back into soluble form under anaerobic conditions. Processes of mineralization, atmospheric deposition, plant uptake, and plant growth/death are also considered. Based on the principle of conservation of mass and reaction kinetics, a coupled system of ordinary differential equations is formulated for the water column, aerobic layer, and anaerobic layer. Mixed explicit-implicit numerical scheme is implemented to solve the coupled system of ordinary differential equations and predict concentration profiles of organic and mineral phosphorus constituents. The developed numerical model is verified against analytical solutions obtained from simplified scenarios, and application to a case-study wetland is presented in the second part of this sequel. Qualitative and quantitative global sensitivity analyses are carried out using Monte Carlo simulation and computing Pearson product moment correlation and Spearman's rank correlation coefficients for the parameters to identify most important parameters and dominant processes controlling transport and fate of organic and mineral phosphorus.
