[Efficiency and Mechanism of Capping with Purple Parent Rocks to Control Phosphorus Release from Sediments]

In order to study the efficiency and mechanism of capping with purple parent rocks to control phosphorus release from sediments, three kinds of purple parent rocks (Fei-xian-guan Formation, Peng-lai-zhen Formation and Sui-ning Formation) which distribute widely in Chongqing, and two types of rock (limestone and calcite) which have been found to effectively control the release of phosphorus from sediments, were selected as active covering materials to cap the sediments to conduct simulation experiment. The results indicated that: all three kinds of purple parent rocks showed strong inhibition of total phosphorus release from sediments to the overlying water, far better than limestone and calcite (P<0.05), and the highest removal rate of total phosphorus was 94.4% in the disposal of Fei-xian-guan Formation. Those five kinds of covering materials could promote the release and transformation of total phosphorus in sediments, which could significantly promote the in situ conversion of OP to Ca-P, while the three kinds of purple parent rocks were more conducive to convert the released phosphorus into inorganic phosphorus and organic phosphorus. At the same time, those five kinds of covering materials could also change the microbial community structure in sediments and overlying water, and the numbers of bacteria (labeled as PLFA16:0) were significantly negatively correlated with the content of total phosphorus in the overlying water.