Three Gorges Reservoir: metal pollution in surface water and suspended particulate matter on different reservoir operation periods

Heavy metals in surface water and suspended particulate matter (SPM) from the Yangtze River, the Jialingjiang River, the Wujiang River and the Three Gorges Reservoir (TGR) were detected to clarify the effects of water input on water quality of the TGR during the water impoundment period (October 2014) and water releasing period (January 2015), respectively. The results showed that metals concentrations in surface water were in the low range and showed different trends. Metals concentrations in SPM also presented various tendencies. In October 2014, significant or highly significant correlations were found between all the elements except for Ni, Cu and Zn. In January 2015, highly significant correlations were detected between Al, As, Cd, Sn, Sb and Ba, suggesting that these elements may share the same source in SPM. Heavy metal pollution evaluation of surface water and SPM showed that water samples sampled from water impoundment period (October 2014) of TGR suffered more heavy metal pollution than that from water releasing period (January 2015) and waters in the three most important input rivers of TGR were more polluted than waters in TGR, while it showed the opposite trend in SPM. We also found that SPM in January 2015 was more polluted by heavy metals than that in October 2014. As the water quality of TGR is most affected by the three input rivers (the Yangtze River, Jialingjiang River and Wujiang River), some of pollutants especially elements of Cd, Pb and Zn embedded in SPM showed accumulation during the two sampling campaigns and may cause adverse effect to water quality of TGR.