Characteristic Research On The Organic Phosphorus And Calcium Phosphorus In Erhai Sediments

A sequential extraction method and a calcareous soil inorganic phosphorus fractionation method were used to grade the calcium and phosphorus [Ca2-P, Ca8-P, refractory calcium and phosphorus (mainly of Ca10-P)]; the Bowman-Cole organic phosphorus classification methods and enzymatic hydrolysis experiment were used to study the phosphorus occurrence characteristics and bioavailability of lake Erhai; under the the Erhai environmental conditions, a simulation experiment was designed to explore the effect of changes in water environmental conditions on organic phosphorus content change and its bioavailability of the Erhai sediment.The results showed that the total phosphorus content of Erhai Lake sediment was710.30-1961.23mg/kg, average phosphorus content was967.59mg/kg, organic matter content was25.03-117.20g/kg, and average organic matter content was48.96g/kg, so Erhai had higher inorganic phosphorus content and lower organic phosphorus content. Total phosphorus content and organic matter content of Erhai Lake were high, but its water quality is good. Erhai Lake sediments The content of refractory releasable phosphorus (calcium and phosphorus, and refractory phosphorus) was higher in Erhai Lake sediments, and calcium and phosphorus content was between210.25-429.45mg/kg, in which the Ca2-P and Cag-P content was very low, and refractory calcium and phosphorus activity fluctuated. Therefore, the higher proportion of the inorganic phosphorus occurrence characteristics of the Erhai Lake sediments, especially calcium and phosphorus and refractory calcium and phosphorus, was one of the reasons why the water quality was relatively good. According to the changes of calcium and phosphorus in Erhai Lake columnar sediments, it can be seen that there exist conversion mechanisms between the calcium and phosphorus components in the Erhai Lake, which may be related to the growth of Erhai submerged plants and their absorption and transformation of calcium and phosphorus. Currently, the water dissolved oxygen content (6.28～7.62mg/L) and pH (8.16to9.36) of Erhai Lake is unfavorable for its sedimental iron phosphate and aluminum phosphate release.According to the reduced content of dissolved oxygen and increased pH value of the Erhai Lake year by year in recent years, the simulation experiment was designed. The simulation experiment data showed that changes in total organic phosphorus content of the Erhai sediment were smaller, and so were the changes in the stable organic phosphorus content. The effect of pH on organic phosphorus content and transformation was related to the characteristics of the sampling points, of which medium organic phosphorus decreased more in the Erhai E07, E13point under the treatment of aerobic, high pH value; the E01, E07, E09, E13area without distribution of submerged plants were conducive to the release of organic phosphorus under aerobic conditions, and with the increase in pH value, the release trended to increase. The effect of changes in Erhai sediment environmental conditions on the active organic phosphorus and medium active organic phosphorus was greater. On the whole, the easier for activity organic phosphorus release under aerobic conditions in the Erhai Lake sediments; Activity organic phosphorus is more difficult to release under anaerobic conditions in the Erhai Lake sediments. That probably due to increase in microbial activity under aerobic conditions, conducive to the mineralization and decomposition of organic phosphorus in Erhai sediments. In addition to the Erhai E02, the contents of medium live organic phosphorus were relatively higher under aerobic conditions in other processing; the contents of medium live organic phosphorus were relatively lower under anaerobic conditions in other processing. The conversion of medium live organic phosphorus to activity organic phosphorus was more favored under anaerobic conditions in the Erhai sediments. Erhai E02was contrast and more special (submerged plants), we can see that the conversion of organic phosphorus was related to physical and chemical properties and submerged plants in the Erhai sediments.From erhai sediment organic phosphorus bioavailability, Overall performance is DOP>LOP>MLOP. DOP bioavailability were higher,Exclude E02, Other treatment Under aerobic condition Under aerobic condition LOP, Alkaline phosphatase、phosphodiesterase Hydrolysis LOP Ability stronger. showed that Release LOP Ability stronger. Under anaerobic conditions, Little change in Alkaline phosphatase, phosphodiesterase Active. The corresponding LOP Smaller Variation. Deal with submerged plants result contrary. MLOP Bioavailability Smaller, so Content MLOP change to other fractions of organic phosphorus.