Microcosm studies on anaerobic phosphate flux and mineralization of lake sediment organic carbon.
Lake sediment has long been recognized as an important source of nutrients such as phosphorus. To gain a better understanding of phosphorus flux at the sediment-water interface, it is crucial to investigate the sediment porewater. There is also growing concern and interest in identifying whether organic-rich sediment is an important source of greenhouse gases such as CO(2) and CH(4). In the present study, we took sediment samples from West Lake, a shallow hypereutrophic lake in Hangzhou, Zhejiang Province, China and incubated subsamples under anaerobic conditions at 25 degrees C for 182 d using a specially designed microcosm that permits repeated extraction of sediment porewater and sampling of headspace gases. Anaerobic phosphate fluxes and mineralization of sediment organic carbon were measured. Average diffusive flux of soluble phosphorus was 0.81 mg P m(-2) d(-1) during the initial 18 d of incubation. Decomposition of sediment organic C followed zero-order reaction kinetics and methane accounted for about 50% of the mineralization products. The results suggest that organic-rich sediments can be important sources of P and methane under anaerobic conditions. Laboratory studies simulating field conditions and field studies are necessary to determine the contribution of sediment as a source of P and greenhouse gases.
Song
Jing
J
Soil and Environment Bioremediation Research Center, State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, P.O. Box 821, Nanjing 210008, China.
Luo
Yongming
Y
Zhao
Qiguo
Q
Christie
Peter
P
D002244:Carbon / Q000737:chemistry*; D004784:Environmental Monitoring; D005068:Eutrophication; D019015:Geologic Sediments / Q000737:chemistry*; D009930:Organic Chemicals; D010710:Phosphates / Q000032:analysis / Q000737:chemistry*; D016062:Porosity; D012995:Solubility; D014881:Water Supply
D009930:Organic Chemicals; D010710:Phosphates; D002244:Carbon