Dynamic monitoring and causes analysis of manganese pollution of Wangquan Reservoir,Qingdao

Base on the full grasp of natural geographical overview of Wangquan Reservoir,Qingdao,water quality and sediment quality was monitored dynamically in July,August,September and November,2011.The results showed that temperature stratification of reservoir changed with different seasons in different parts of reservoir.In the areas where water depths were greater than 8 m,temperature stratification started in summer and the thermocline was formed in mid-August;water above the thermocline was in oxygen-rich condition,while DO decreased rapidly blew the thermocline,temperature stratification disappeared after fall,the concentration of DO was about 8 mg/L.In other areas,there was no temperature stratification and water was always oxygen-enriched;the concentration of soluble manganese of tributary inflow was low whereas sediment was full of manganese,it reflected the main reason of manganese pollution was internal release;the water more than 8 m deep was changed from oxidation status into reduction status as the thermocline formed in summer.Manganese was released largely from sediment with the maximum concentration was up to 1.28 mg/L.The release of manganese was restrained after fall because temperature stratification was disappeared and water was in oxidation state.There was no manganese pollution found in area of water depth lower than 8 m,because the water was in oxidation state all the year.