Spatial and temporal variation of water quality of Pearl River in Guangzhou, China

Understanding the spatial and temporal variation of water quality of Pearl River passing through the city of Guangzhou is essential knowledge for developing management strategies to protect this important water resource for over 10 million people in Guangzhou. Water samples were collected at least once a month at 12 locations along Pearl river in the Guangzhou section including its north and south tributaries, and analyzed for basic water quality parameters, including temperature, pH, electrical conductivity (EC), total suspended solid (TSS), volatile suspended solid (VSS), ultraviolet absorbance at 254nm (UVA) and turbidity for year 2008 - 2009. Upstream samples were collected from shore and center-river in seven months. Water samples were also collected at least every 2 hour for a day at two locations and once a day for a week at three locations. Temperature in downtown was higher, and had a much lower fluctuation than rural area. Upstream water had a lower pH than midstream and downstream. EC of north midstream was higher than that of south midstream. July, the hottest month of Guangzhou, were detected a lower EC, in contrary to December and January, the coldest time, which were detected a higher EC. TSS has a lowest concentration in April, the wettest month, but VSS did not have significant temporal variation throughout a year. Also, VSS had a higher concentration in north tributary than south tributary. This trend was not found in TSS, but the outlet of north tributary had a higher TSS and VSS concentration than that of south tributary. Upstream water was recorded significant higher UVA than midstream and downstream. There was no significant difference between north and south tributary in pH, turbidity and UVA. EC and pH almost didn’t fluctuate throughout a day. There was a strong correlation between shore samples and center-river samples in temperature, pH, EC, turbidity and UVA.