Effect of Exotic Sulfate on Phosphorus Mobilization in the Sediment of Nanhu Lake in Wuhan
|School||Huazhong Agricultural University|
|Keywords||Internal phosphorus Sulfate reduction P Fractions Organophosphorus 31P-NMR|
The lake eutrophication prominent water environmental issues, water - sediment interface the conversion zone between the water and sediments, is a special and important area of ??the water environment. On the one hand, when the lake outside source pollution control as endogenous sediments become an important source of phosphorus in the water body. On the other hand, sulfate input lakes increasing, this situation will affect the migration and transformation of the lakes within the source phosphorus. Subject to water - sediment interface, select Nan lake and the corresponding overlying water through laboratory simulation, the impact of exogenous sulfate on sediment phosphorus cycle, the main conclusions are as follows: (1) sulfate The reduction significantly change the physical and chemical properties of the sediments in South Lake had a major impact on the factors affecting phosphorus release from sediment pH and Eh, sulfate-reducing bacteria (Sulfate reduction bacteria, SRB) in the process of sulfate reduction, the pH of the surface sediments The value was significantly higher. There is a negative correlation between Eh and pH, sulfate input Eh significantly reduce the surface sediments. (2) S042-reduction product of acid volatile sulfur (mainly H2S, FeS) and chromium reduction of sulfur, these substances are usually trapped in the sediments to precipitate form (Acid volatile sulfide, AVS). The beginning of the experiment, AVS is the main form of existence, late due to the occurrence of FeS S0 → FeS2, AVS into the more stable of FeS2. The AVS content with sediment Eh significant correlation, in this study, three weeks after the experiment, pH lowering elevated Eh value, AVS decreased. (3) sulfate reduction index (Sulfate reduction index, SRI) increases with increasing input concentration of SO42-, sulfate-reducing effect and more intense, and at the same time, strengthening the SRB degradation of organic matter under anaerobic conditions. both were negatively correlated with the conduct of sulfate reduction, sediment organic matter is consumed decreased gradually. (4) sulfate reduction significantly promoted the activity of organic phosphorus (Labile organic phosphorus, LOP) mineralization the sediment iron of Fe (III); with Eh reduce, chemical reactions → Fe (II), Fe / P decreased iron bound phosphorus to be released at the same time, the combination of sediments AVS and FeS2 generation of so Fe P043-release, increased the phosphorus content of the water - sediment interface; addition, sulfate reduction also makes the deposition The pH was increased, the OH-and phosphate anions competitive adsorption sites, phosphorus-P043-form exist, not easily adsorbed by the sediment is fixed, so that was dissolved into water to increase in phosphorus content. Ca2-P content increases, in the experiment may be due to the organic phosphorus in the phytic calcium phosphate mineralization converted to Ca2-P. (5) using 31P nuclear magnetic resonance (31P-NMR) determination of the molecular shape and the relative content of NaOH-EDTA extracts in sediment phosphorus compounds. The results show that the South Lake sediment phosphorus component orthophosphate, phosphate monoester, diester phosphate and pyrophosphate, and orthophosphate content dominant content of 84.1-95.5%, biological phosphorus content of the order The phosphate monoester gt; the phosphoric diester GT; pyrophosphates. SRB proliferation, sulfate reduction can significantly promote the the orthophosphate sediments overlying water release.