Korean Journal of Soil Science and Fertilizer ISSN:0367-6315(Print) 2288-2162(Online) 한국토양비료학회 학회지

This study aimed to identify the changing trends in the agricultural water quality of the major watersheds in Gyeonggi Province over a 10-year period ranging from 2007 to 2016. The results of water quality analysis of the study sites revealed that the mean chemical oxygen demand was 3.8 mg L^-1, with the median values being 3.5 mg L^-1. The mean chemical oxygen demand in April, July, and October were 4.7, 3.8, and 3.1 mg L^-1, respectively, and chemical oxygen demand values trended to decrease from April to October. The mean and the median electrical conductivity were 0.22 dS m^-1. The mean electrical conductivity values were slightly higher in April and lower in October, and there was no yearly fluctuation. The mean and median values of the T-N (Total Nitrogen) content were 3.3 mg L^-1 and 3.0 mg L^-1, respectively. The mean and median values of the T-P (Total Phosphorous) content were 0.10 mg L^-1 and 0.06 mg L^-1, respectively, and there was no tendency to increase or decrease during the April, July and October.

Changes in annual water quality index in April (left), July (center), and October (right).