Nitrate-Nitrogen Transport in Horizontal Soil Columns of the Yellow River Delta Wetland, China

Abstract

Horizontal movement of nitrate-nitrogen was simulated in horizontal soil columns from a typical tidal flooding wetland and a short-term flooding wetland of the Yellow River Delta. The primary objectives of this study were to investigate the changes in transport fluxes of nitrate-nitrogen with increasing movement distances and to identify the relationship between transport fluxes of nitrate-nitrogen and water diffusion coefficients. The results showed that the transport fluxes of nitrate-nitrogen were significantly and negatively correlated with movement distances in both wetlands, and decreased exponentially with increasing distances. However, the transport fluxes of nitrate-nitrogen increased exponentially with increasing water diffusion coefficients in both wetlands. The higher transport fluxes of nitrate-nitrogen in surface soils were observed compared to deeper soils, while they were higher in surface soils at the distances near the tracer water head. The findings of this study can contribute to water quality protection by regulating buffer zone width based on the horizontal movement of nitrate-nitrogen. A simulation of the movement of nitrate-nitrogen in horizontal soil columns was carried out in the laboratory. Compared to tidal flooding wetland, short-term flooding wetlands had higher risk of nitrate movement to the adjacent water, because nitrate transport rates are higher in this wetland with lower soil pH and higher sand contents. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.