ZHANG Hong1, 2, CHEN Jingan1, *, WANG Jingfu1,2, YANG Haiquan1, 2, JI Yongxue1,2
(1. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China;
2. University of Chinese academy of sciences, Beijing 100049, China)
Abstract: A laboratory simulation study on release of phosphorus from the sediment in Lake Hongfeng, Guizhou Province, China was conducted by controlling temperature, dissolved oxygen(DO), pH, disturbance and microbes. Our results show that: (1) the amount of sedimentary phosphorus release increases with rising temperature. When T= 5℃, the flux of sedimentary phosphorus release is 0.41 mg·m-2·d-1. When T= 25℃ and T=35℃, the flux of sedimentary phosphorus release is 0.87 and 2.56 mg·m-2·d-1, respectively; (2) Under anaerobic condition(DO<2.0 mg/L), the sediment obviously releases phosphorus to the overlying water; the flux of sedimentary phosphorus release is 0.80－3.18 mg·m-2·d-1. Under aerobic condition(DO>6.0 mg/L), the flux of sedimentary phosphorus release is only 0.57 mg·m-2·d-1; (3) The release of sedimentary phosphorus is closely related to pH of the overlying water and the amount of sedimentary phosphorus increase with rising pH. When pH=5.5 and pH=7.5, the flux of sedimentary phosphorus release is 0.80 and 0.87 mg·m-2·d-1, respectively. When pH=9.5, the flux of sedimentary phosphorus release is 3.18 mg·m-2·d-1; (4) Under disturbed condition, the flux of sedimentary phosphorus release (1.82 mg·m-2·d-1) is higher than the undisturbed one(0.87 mg·m-2·d-1); and (5) Microbes influence the release of sedimentary phosphorus to the overlying water significantly. Under sterilized condition, the amount of sedimentary phosphorus release is larger than the microbial influence. In summary, high temperature, anaerobic condition，high pH, and intense disturbance could stimulate release of sedimentary phosphorus. Notably, microbes significantly inhibites sedimentary phosphorus release to the overlying water. Based on results of the laboratory simulation study, the fluxes of sedimentary phosphorus release under different environmental conditions were calculated and the estimated amount of sedimentary phosphorus release during summer thermal stratification(6－9 months) was 6 t, accounting for 21.4% of total phosphorus load of the water body(about 28 t) and indicating that the release of sedimentary phosphorus make an important contribution to phosphorus load and eutrophication of the water body. It is therefore urgent to manage the polluted sediment in Lake Hongfeng.
Keywords: Lake Hongfeng; sediment phosphorus; amount of release; flux of release
EARTH AND ENVIRONMENT Vol. 43, No.2, Tot No.304, 2015, Page 243-251
