Spatial distribution of water quality parameters of rivers around Erhai Lake during the dry and rainy seasons

Abstract

Surface water from 18 rivers (including the buffer zone and lakeside area) around Erhai Lake was sampled in the dry and rainy seasons of 2013. The water quality was measured and the spatial variations of selected water quality parameters were determined. The results indicated that the following five parameters, ρ(TN), ρ(NO3 −-N), ρ(NH3-N), ρ(TP), and ρ(CODMn), in the surface water of the 18 rivers changed seasonally. The average value of ρ(TN), ρ(NO3 −-N), ρ(NH3-N), ρ(TP), and ρ(CODMn) in the rainy reason was higher than that in the dry season, respectively. The average value of ρ(TN) in three rivers (Mijuhe, Yonganjiang, and Luoshijiang rivers) flowing into the lake from the north was clearly higher than that in rivers flowing into the lake from the west. In contrast, the average value of ρ(TP) in the three northern rivers was lower than that in the western rivers. In the dry season, the distribution of ρ(TP) had a significant positive correlation with the distribution of ρ(TN), but this was not significant in the rainy season. The average value of ρ(CODMn) was within the Class I of “Surface Water Environmental Quality Standards of China”.