Nutrient Dynamics in Flooded Wetlands. II: Model Application

Abstract

In this paper, the authors applied and evaluated the wetland nutrient model that was described in Paper I. Hydrologic and water quality data from a small restored wetland located on Kent Island, Maryland, which is part of the Delmarva Peninsula on the eastern shores of the Chesapeake Bay, was used for this purpose. The model was assessed through various methods against the observed data in simulating nitrogen (N), phosphorus (P), and total suspended sediment (TSS) dynamics. Time series plots of observed and simulated concentrations and loads generally compared well; better performance was demonstrated with dissolved forms of nitrogen, i.e.,ammonia and nitrate. Through qualitative and quantitative sensitivity analysis, dominant processes in the study wetland were scrutinized. Nitrification, plant uptake, and mineralization were the most important processes affecting ammonia. Denitrification in the sediment layer and diffusion to bottom sediments were identified as key processes for nitrate. Settling and resuspension were the most important processes for particulate matter (organic N, sediment) and sediment-bound phosphate (inorganic P). Order of parameter sensitivities and dominant processes exhibited seasonality. Uncertainty bands created from Monte Carlo simulations showed that parameter uncertainty is relatively small; however, uncertainty in the wetland inflow rates and loading concentrations have much more bearing on model predictive uncertainty. N, P, and TSS mass balance analysis showed that the wetland removed approximately 23, 33, and 46%, respectively, of the incoming load (runoff + atmospheric deposition) over the two-year period, with more removal in year 1 (34, 43, and 55%, respectively), which had a long stretch of a dry period. The developed model can be employed for exploring wetland response to various climatic and input conditions, and for deeper understanding of key processes in wetlands

Capturing Spatial Variability of Biogeochemical Mass Exchanges and Reaction Rates in Wetland Water and Soil through Model Compartmentalization

“…WetQual is a process-based model for sediment, nitrogen, phosphorus, and carbon retention, cycling, and removal in flooded wetlands Kalin et al 2013;Sharifi et al 2013). The model simulates oxygen dynamics and the impact of oxidizing and reducing conditions on nitrogen and carbon transformation and removal, as well as phosphorus retention and release.…”

“…The vertical soil layer is partitioned into aerobic and anaerobic zones where the boundary between the two zones fluctuates up or down based on competing oxygen supply and removal rates. Readers are referred to Hantush et al (2013), Kalin et al (2013), and Sharifi et al (2013) for more detailed information regarding model structure, governing equations, and case study applications of WetQual.…”

“…Definitions for these parameters are found in Table 3. The confidence level was set at P < 0.10 as opposed to previous WetQual application studies (Sharifi et al 2013;Kalin et al 2013), because few parameters were sensitive at the p < 0.05 confidence level. The reason behind this observation may be attributed to limited observation data for validation and to a large pool of model parameters.…”

Efficacy of the Cruciferous Vegetable on the Thyroid Gland and the Gonads in Rabbits

“…Kalin et al (2013) had reported that the goitrogenes can cross into the fetus during lactation and the transfer of iodine cross ma ternal milk and placenta into the fetal bloodstream is inhibit by these goitrogenes.…”

Carbon dynamics and export from flooded wetlands: A modeling approach

“…Sources for other input data (precipitation, temperature, etc.) used in the model could be found in Kalin et al (2012) who validated the N and P cycles of WetQual model on the same study wetland. Unfortunately the dataset does not include methane emission measurements, so we were not able to completely validate the methane component of the model.…”