ZHANG Hong^{1, 2}, CHEN Jingan^1*, Zeng Yan^1,2, WANG Jingfu^1,2, YANG Haiquan^{1, 2}

(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550180, China;
2. University of Chinese academy of sciences, Beijing 100049, China)

 

Abstract:A simulation study on calcium nitrate restraining the release of phosphorus from sediments of Lake Hongfeng, Guizhou Province, Chinawas performed, and its environmental effects and possible mechanism were also discussed.Results show that calcium nitrate can effectively reduce the soluble and active phosphorus in the pore water and the overlying water. The optimal dosage of calcium nitrate used for sediments from Lake Hongfeng was 187.5 g/m2. By using calcium nitrate, NH4+-N concentration in the overlying water decreases to meet the criterion of NH4+-N for class III water quality enacted by Chinese government and the induced pollution of heavy metals in water body is negligible, suggesting that calcium nitrate is environmentally safe. The corresponding mechanism was listed as follows,1)the added calcium nitrate can accelerate microbial denitrification of the sediments, and in the meantime, dissolved organic carbon is degraded with the consumption of the nitrate; 2)the added calcium nitrate can oxidize Fe2+ in sediments into the form of Fe3+, which help to the formation of iron oxide and oxide-hydroxide, thus significantly decreases SRP in the pore water and the overlying water. In conclusion, calcium nitrate can effectively restrain the release of phosphorus from sediment and could be an efficient agent for in situ passivation of phosphorus in sediment. This study could provide an effective method for restraining the release of endogenous phosphorus in sediment.

 

Key words: Calcium nitrate; Sediments; Phosphorus; Simulation study

 

EARTH AND ENVIRONMENT Vol. 43, No.5 Tot No.307, 2015, Page 565-571