Temporal and spatial distribution characteristics of Nitrogen in the headwaters of Xin’anjiang Watershed: A comparison study between the pre-flooding and post-flooding seasons
The headwaters of Xin’anjiang in Shangxikou area, Xiuning County, Anhui Province was selected as the study site to investigate the temporal and spatial distribution of nitrogen in the source area. Through field sampling, water quality monitoring and statistical analysis, the temporal and spatial distribution characteristics of various monitoring indexes and their influencing factors in pre-flooding and post-flooding seasons were studied, and the influence of flood on river nitrogen dynamics in the source area of Xin’anjiang River was revealed. The results show that the total nitrogen concentration increases gradually along the water flow path. Compared with pre-flooding season, the concentration of total nitrogen, ammonia nitrogen and nitrate nitrogen increased in post-flooding season. During the flood period, the rainwater “scoured off” the nitrogen in the watershed. The correlation analysis shows that nitrate and total nitrogen are greatly affected by vegetation in pre-flooding season. The concentration of nitrate nitrogen is related to the watershed area and the total nitrogen concentration is affected by elevation, slope and geology in post-flooding season. The regression models performs well in the prediction of nitrate and total nitrogen concentrations in pre-flooding season and that of ammonia and nitrate nitrogen concentrations in post-flooding season.