A nutrient enrichment experiment was conducted in situ in Donghu Lake （30°33′N, 114°23′E）, a shallow hypereutrophic lake in Hubei, China through an enclosure（each 2.5×2.5m by 2 m depth） method fro...A nutrient enrichment experiment was conducted in situ in Donghu Lake （30°33′N, 114°23′E）, a shallow hypereutrophic lake in Hubei, China through an enclosure（each 2.5×2.5m by 2 m depth） method from July 15 to September 21, 2000. Three duplicated groups, including two treatments and one control, were designed as unfertilized control （C）, nitrogen enrichment （N） and phosphorus enrichment （P）, and were also compared with neighboring lake water. Dense Microcystis bloom exclusively dominated in all the enclosures, while no bloom was observed in the lake. All the enclosures had much higher phytoplankton biomass, higher pH values, and higher transparency than the surrounding lake water Neither nitrogen nor phosphorus addition had significant effect on phytoplankton composition and biomass due to very high nutrient concentration in the lake water. Suitable biological （absence of filter-feeding silver carp and bighead carp） and physical environment （high transparency, high stability and high pH） associate with saturated nutrient concentration contribute to the nuisance Mieroeystis bloom in the enclosures.展开更多
Gypsum-salt rocks and coccolith calcareous shale are widely deposited in the lower part of the Paleogene Shahejie Formation in the Dongying Sag, Sbandong Province. The gypsum-salt rock is believed to be formed during ...Gypsum-salt rocks and coccolith calcareous shale are widely deposited in the lower part of the Paleogene Shahejie Formation in the Dongying Sag, Sbandong Province. The gypsum-salt rock is believed to be formed during the earlier deposition in salt lake, while the overlying coccolith shale in saline lake with relatively low salinity. By comparing the lake environment and la- custrine microbial communities between ancient and recent lakes, cyanobacteria are regarded as the main representative of productivity during the formation of gypsum-salt strata series, with the annual productivity of 1500-2000 gC m-2 yr1. Based on the research of ultramicrofossils in the calcareous shale, coccolith is considered as the main contributor to the productivity during the formation of calcareous shale. On the basis of statistic data of sedimentary rates, shale laminations, and coccolith fossils in each lamination, the quantitative value of productivity is calculated, with the annual productivity of 2250 3810 gC m 2 yr-1 （averagely 3120 gC m-2 yr-1）. Statistic data of large amount of pyrite framboids indicate that the lower water col- umn was persistently in sulfidic or anoxic conditions during the deposition of gypsum-salt strata series, but it changed to be dysoxic when the coccolith calcareous shale was deposited. Both of these water conditions are favorable for the preservation of organic matter. It is estimated that the organic carbon burial efficiency of the Lower Paleogene salt lakes and saline lakes of Dongying Depression is about 10%-15%, which is calculated and analyzed using the multi-parameter geobiological model.展开更多
基金Supported by a key project of the Chinese Academy of Sciences (No. KZCX1-SW-12) and by Foundation of South China Agricultural Univer-sity for Doctors (No. 4300-K05108).
文摘A nutrient enrichment experiment was conducted in situ in Donghu Lake （30°33′N, 114°23′E）, a shallow hypereutrophic lake in Hubei, China through an enclosure（each 2.5×2.5m by 2 m depth） method from July 15 to September 21, 2000. Three duplicated groups, including two treatments and one control, were designed as unfertilized control （C）, nitrogen enrichment （N） and phosphorus enrichment （P）, and were also compared with neighboring lake water. Dense Microcystis bloom exclusively dominated in all the enclosures, while no bloom was observed in the lake. All the enclosures had much higher phytoplankton biomass, higher pH values, and higher transparency than the surrounding lake water Neither nitrogen nor phosphorus addition had significant effect on phytoplankton composition and biomass due to very high nutrient concentration in the lake water. Suitable biological （absence of filter-feeding silver carp and bighead carp） and physical environment （high transparency, high stability and high pH） associate with saturated nutrient concentration contribute to the nuisance Mieroeystis bloom in the enclosures.
基金supported by National Science and Technology Major Project (Grant No. 2009ZX05009)National Basic Research Program of China (Grant No. 2011CB808800)+1 种基金National Natural Science Foundation of China (Grant Nos. 41172036, 40730209)the "111" Project (Grant No. B08030)
文摘Gypsum-salt rocks and coccolith calcareous shale are widely deposited in the lower part of the Paleogene Shahejie Formation in the Dongying Sag, Sbandong Province. The gypsum-salt rock is believed to be formed during the earlier deposition in salt lake, while the overlying coccolith shale in saline lake with relatively low salinity. By comparing the lake environment and la- custrine microbial communities between ancient and recent lakes, cyanobacteria are regarded as the main representative of productivity during the formation of gypsum-salt strata series, with the annual productivity of 1500-2000 gC m-2 yr1. Based on the research of ultramicrofossils in the calcareous shale, coccolith is considered as the main contributor to the productivity during the formation of calcareous shale. On the basis of statistic data of sedimentary rates, shale laminations, and coccolith fossils in each lamination, the quantitative value of productivity is calculated, with the annual productivity of 2250 3810 gC m 2 yr-1 （averagely 3120 gC m-2 yr-1）. Statistic data of large amount of pyrite framboids indicate that the lower water col- umn was persistently in sulfidic or anoxic conditions during the deposition of gypsum-salt strata series, but it changed to be dysoxic when the coccolith calcareous shale was deposited. Both of these water conditions are favorable for the preservation of organic matter. It is estimated that the organic carbon burial efficiency of the Lower Paleogene salt lakes and saline lakes of Dongying Depression is about 10%-15%, which is calculated and analyzed using the multi-parameter geobiological model.
