Relationships of nitrogen losses, phosphorus losses, and sediment under simulated rainfall conditions

Abstract

Losses of nitrogen (N) and phosphorus (P) often occur during the process of soil erosion and are often the primary sources of water eutrophication. Using artificial rainfall experiments, this study analyzed the characteristics of N and P losses and relationships of N losses, P losses, runoff volume, and sediment yield. The results indicated that N, P, and sediment loss rates had significant variations in the beginning and became stable in the middle and late stages of runoff for single rain events. The ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3−-N), and dissolved phosphorus (DP) were transported primarily through runoff water, which accounted for approximately 92.6%, 98.1%, and 89.4% of their respective totals. However, the losses of total nitrogen (TN) and total phosphorus (TP) in runoff water only accounted for 50.4% and 9.7% of their respective totals. The loss rates of N, P, and sediment had significant relationships with runoff rate or rainfall, and N and P loss rates had significant relationships with sediment loss rate as well. Ammonium nitrogen, TN, and TP enriched sediment at different degrees for single rain events, and the enrichment with TP was the most significant, especially under the rainfall intensities of 120 mm h−1 and 180 mm h−1.