The Characteristics Of Internal Nitrogen Loading In Dianchi Lake Sediment And Bioavailability Of Dissolved Organic Nitrogen(DON) From Different Sources Of Dianchi Lake

The eutrophication of Dianchi lake is a major ecological and environmental problems,especially, in recent years with the development of society and economy, the ecologicalproblems have become increasingly prominent, the endogenous nitrogen load characteristic andthe different sources of dissolved organic nitrogen biogeochemical cycle may be maintained, isthe key factor of eutrophication in Dianchi. Microbial utilization is an important process of waterecological system of dissolved organic nitrogen biogeochemical cycle. This paper takes Dianchidifferent sources(Dianchi, into the lake river and rainfall) dissolved organic nitrogen as the objectof study, cultivating effective technology to characterize its biological utilization of microbial,trying for the organic nitrogen bioavailability of Dianchi dissolved the objective understandingand provide the scientific basis for evaluation. The paper draws the conclusion as follows:(1)the average total nitrogen content of surface sediment in Dianchi Lake was 3515.60 mg/kg,which were at high level from the inlets in Caohai Northeast thinning digging area, Panlong Riverand the Haikou into Dianchi Lake, but relatively lower in Baoxiang River Estuary dredging area.The total organic nitrogen(TON) content, accounts for 85.86% of TN, was at a high level; on theother hand, the dissolved inorganic nitrogen(DIN) content was lower, which accounting for14.10% of TN, The spatial distribution of TON and TN keep the same surface sediment inDianchi Lake was 3515.60 mg/kg, which were at high level from the inlets in Caohai Northeastthinning digging area, Panlong River and the Haikou into Dianchi Lake, but relatively lower inBaoxiang River Estuary dredging area. The total organic nitrogen(TON) content, accounts for85.86% of TN, was at a high level; on the other hand, the dissolved inorganic nitrogen(DIN)content was lower, which accounting for 14.10% of TN, The spatial distribution of TON and TNkeep the same trend, but not the DIN. Compared with other Lakes of China, the nitrogen contentof sediment in Dianci were at a high level, and the extent of pollution just below the seriouspolluted City Lakes.(2)The average potential mineralizable nitrogen(PMN) content of Lake Dianchi was 1154.76mg/kg, accounting for 32.90% of TN, which raise higher potential risk of its release into overlying water. The higher PMN had been found in the Caohai Lake area and the inlet of PanlongRiver in the North, the inlet of Luolong Rive in the Middle Lake, the inlet of Baiyukou Lake andLiangwang River in the South. Nowadays, the p H value of Dianchi Lake was favorable to itssediment nitrogen mineralization, and its nitrogen mineralization was affected by the release ofNH4+-N from organic matter. In the heavy polluted area, the concentration of the overlying waternitrogen was seriously affected by nitrogen mineralization of sediment from Dianchi, while thelight polluted area was less affected.(3)According to the spatial distribution characteristics of Don in sediment of Dianchi Lake,which the choice of Dianchi sediment in different regions of high DON The content and severalpoints of microbial cultivation, biological availability of its DON, the effective part of bioaccounted for 38.48% of the total to 80.41%, from 50% to 70% range. The effectiveness of thesediments in the DON the highest biological, north is relatively high, southern minimum.(4)Taking Dianchi as the research object, the distribution and seasonal variation of the Dianchiwater gap DON bioavailability of in-depth research and analysis, the change from the content andbioavailability differences. Results the spatial distribution of water to obtain effective gapbiological organic nitrogen present from southern North like gradually increasing trend, in therange of 15.6%~96.3%, varied greatly, from a larger area for 5 different degradation amount ofbits as seasonal culture analysis, research between seasons gap water DON bioavailability ofdifferent fall the highest, lower in spring.(5)Study on the technology of Dianchi lake, the use of microbial culture into the lake river andthe effective rainfall of DON biological each month fluctuation, which cover water in summer ofDianchi on the bioavailability was significantly lower than the other seasons, autumn is thehighest, the same season of different regional microorganisms using different amount of DON, theDianchi lake river water cultivation of microorganism after DTN and nitrate nitrogen had noobvious change, while NH4+-N increased significantly after incubation, DON decreased. Anddifferent lakes in the same season in different amount of organic nitrogen bioavailability; the samelake in different seasons of the organic nitrogen bioavailability is different also, its change has alarger difference, the use of rivers into the lake water rate of DON content in the highest andlowest in the middle part of the northern, Dianchi; little rainfall DON seasonal variationbioavailability of degradation, the largest amount in May, other a few months is consistent, in therange of 33.26% ~70.35%.