Spatial distribution of nitrogen in the water from the Baihua Lake

Vertical distribution of inorganic nitrogen in the water from the Baihua Lake and the correlations between nitrogen forms and dissolved oxygen (DO) are analyzed in this study. The concentrations of total nitrogen (TN), ammonia nitrogen (NH4+-N), nitrate nitrogen (N O3--N), nitrite nitrogen (NO2--N) and dissolved oxygen in eight water samples (surface, 4 m, 8 m and 12 m under the water) are determined. The results show that the total nitrogen average concentration of the wateris1.18 mg/L, with ammonia nitrogen being 0.144 mg/L, nitrate nitrogen 0.20 mg/L and nitrite nitrogen 0.018 mg/L. Furthermore, the average concentrations of total nitrogen, ammonia and nitrate nitrogen are higher at the inlet point in comparison to other sampling points. In addition, the correlation analysis demonstrated that there are significant negative correlations between DO concentration and two nitrogen forms (nitrate nitrogen and nitrite nitrogen) with correlation coefficient -0.629 and -0.724.