Nutrient removal in different overlying water layers and their variation in pore water of drainage ditches in Sanjiang Plain, Northeast China

Abstract

Abstract Agricultural drainage ditches which deliver excess water from poorly drained farmlands to ensure consistent agricultural production but also transport field pollutants, especially nitrogen (N) and phosphorus (P). Ditch management has been proposed to alleviate nutrient loads that are transported to receiving water. Experimental drainage ditches with Phragmites australis were used to examine the N and P mitigation capacity of drainage ditches at different plant growth stages and different initial concentrations as well as the mitigation capacity in different water layers by the intermittent strategy. This study also investigated nutrient variations in sediment pore water of drainage ditches under existing ditch management systems. Significant reductions were observed on the efficiencies of nitrate nitrogen (NO3–N) and phosphate phosphorus (PO4–P) with plant growth. The efficiencies of ammonia nitrogen (NH4–N) remained the same at different growth stages. The rates of NH4–N, NO3–N and PO4–P were hi...