Geochemistry Characterstics Of Organic Phosphorus In Lake Sediments Of Cold And Arid Regions, China

As an important nutrient of lake ecosystem, organic phosphorus is a major link of nutrient biogeochemical cycle and the process of life. Organic phosphorus is one form of sediment phosphorus and makes contribution to eutrophication of lakes. The understanding of bioavailability of organic phosphorus was important of expounding environmental behaviors of organic phosphorus in aquatic environment.Lake Wuliangduhai and Lake Hulunhu with significant features of the cold and arid regions are different in lake types. Based on forms and bioavailability of organic phosphorus, the geochemistry characterstics of organic phosphorus in sediments from the two lakes were determined using the sequential extracted methods. The characteristics and mechanism of temporal and spatial distributions were explained. The information of organic phosphorus compounds in sediment cores were interpreted according to 31P-NMR technology. Further, basic data about organic phosphorus in lake ecosystem were statistics to have comparative study on its bioavailability in different regions of China. Accordingly, the main progress are as follows:1. The geochemistry characteristics of organic phosphorus in the two lakes were analyzed on the basis of chemical sequential extraction procedure. The results showed that HC1-OP and Re-OP were dominant forms in sediments from Lake Wuliangsuhai, while Re-OP in Lake Hulunhu. And the same concentration order of LOP<MLOP<NLOP were found in the two lakes.2. The organic phosphorus compounds were determined by 31P-NMR technology. The results showed that there were more peaks of organic phosphorus compounds in surface sediments than bottom sediments from the two lakes due to the hydrolysis of organic phosphorus compounds with low-stability.3. Significant correlation between LOP and ORP were found in Lake Wuliangsuhai revealing the release of LOP during OM degradation. For Lake Hulunhu, the significant correlation between Fe-P/TOC and HCl-OP/NaOH-OP were found indicating that iron oxides could fix organic phosphorus and the mutual transformation between NaOH-OP and HC1-OP maybe the control reaction for organic phosphorus transformation in sediments.4. For Lake Wuliangsuhai, the diffusion fluxes of phosphorus across water-sediment interface and the species distribution of phosphorus during icebound season were detected. It contributed fundamental data sets about the geochemistry behavior of phosphorus in different interfaces in cold and arid region.5. The differences of organic phosphorus in sediments of lakes located in different regions were discussed. It showed that the contents of organic phosphorus in Inner Mongolian Plateau and Qinghai-Tibetan Plateau were lower than those in Middle and Lower Reaches of the Yangtze River Area and Yunnan-Guizhou Plateau. It indicated the differences may be relation to the natural geographical environment, climate conditions and ecnomic development levels in various regions.