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

Horizontal movement of nitratenitrogen 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 nitratenitrogen with increasing movement distances and to identify the relationship between transport fluxes of nitratenitrogen and water diffusion coefficients. The results showed that the transport fluxes of nitratenitrogen were significantly and negatively correlated with movement distances in both wetlands, and decreased exponentially with increasing distances. However, the transport fluxes of nitratenitrogen increased exponentially with increasing water diffusion coefficients in both wetlands. The higher transport fluxes of nitratenitrogen 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 nitratenitrogen.