Water Quality Conservation in an Agricultural Pond using an Ecosystem Model and Scenario Analysis

概要

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To explicate the dynamics of nitrogen and phosphorus in an agricultural pond, numerical simulations were conducted for their temporal fluctuation in pond water by using an ecosystem model, and the developed model was applied to a scenario analysis for the improvement and preservation of water environment by the reduction of nitrogen and phosphorus. In this study, the model was composed of 5 water quality indices-nitrogen oxides, ammonia-nitrogen, organic nitrogen, phosphate-phosphorus and organic phosphorus- and was adapted to the Toishigawara agricultural pond in Fukuoka Prefecture, Japan, where concentrations of total nitrogen and total phosphorous were extraordinarily high. A comparison between the calculated results and the observed data showed that the ecosystem model used in this study could reproduce the dynamics of nitrogen and phosphorus in Toishigawara pond. According to the scenario analysis, 80% reduction of current nutrient inflow load resulted in the remarkable decrease of total nitrogen and total phosphorous concentrations. As a result, total nitrogen fulfilled the water quality standard of irrigation water in Japan.
九州大学の論文