3日 张润宇 湖泊沉积物中磷的生物地球化学循环.ppt

Questions VS Objectives Despite a major component of P in sediments, knowledge of organic P is difficult because of its complexity in composition and structure. Information is limited on the lability of Po fractions and their contribution to the water column in different kinds of freshwater lakes. Concentrations, relative distributions and the recovery of different Po fractions in the sediments Concentrations of Po fractions in different polluted sediments 31P-NMR spectroscopy Procedure 0.25M NaOH/0.05M EDTA extraction; After centrifugation, TP and Pi in the supernatants was determined by molybdate colorimetry; 5～10 times pre-concentration by rotary evaporation at 30 ℃; 5%(v/v) bicarbonate buffered dithionite solution to reduce interference from paramagnetic ions; re-dissolved in 0.5 ml of D2O and 0.2 ml of 10 M NaOH; 31P NMR spectroscopy analyse. The organic matter (LOI) and P contents of the sediments Conclusions The composition of P in sediments from various freshwter lakes (e.g., hypertrophic, mesotrophic, eutrophic, deep and shallow lakes) varied greatly, hence affecting the lability of Po and its contribution to lake eutrophication. * * Biogeochemical cycle of P in sediments of different freshwater lakes, China 13th World Lake Conference, Wuhan, China Zhang Run-yu Aassociate professor State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, CAS, Guiyang 550002, China zhangrunyu@mails.gyig.ac.cn Introduction Chinese lake distribution map ★ Beijing 2300 lakes with a water surface＞1 km2. ＞50% of urban drinking water source from the lakes. 80% of these lakes have been contaminated, and 62% of the total water bodies are in eutrophication. freshwater lakes brackish and salt lakes Eutrophication: Focus on Phosphorus Relationships between Chl-a and TP/TN Annual Summer Annual Summer Wang H, et al. Freshwater Biology. 2008, 53: 935–944 35 shallow lakes and 10 fishponds from the mid-lower Yangtze Basin, Field investigations from 20