Phosphorus Speciation And Distribution At The Sediment-Water Interface Of FuNan River

Phosphorus is a key nutrient in aquatic environments, but excessive phosphorus mayresult in water deterioration. For enclosing water pollution status in FuNan River-atypical urban river, phosphorus species in water and column-sediments were investigated. Expression of results are as follows:1 The levels of total Phosphorus obtained in overlying water were much higher than the international accepted critical Levels (TP: 0.02mg/L), and "National surface water quality standard" set out in Class V water limit (0.2 mg /L) .The average concentration of TP in two rivers is 2.14mg/L, 1.52mg/L respectively. Particulate Phosphorus is the main fraction, accounted for 54.2% of TP in Fu and 60.5% in Nan river.2 The concentration of TDP in interstitial water: In Fu river, range from 0.17 mg/L to 0.90mg/L, it presents as declining with depth and maintained steady at deeper part; In Nan river, range from 0.091 mg/L to 2.07mg/L, its vertical variation with depth prensents as raise-fall-steady. Dissolved Phosphorus in overlying water have the direction to diffuse into interstitial water, sediment should act as a more effective Phosphorus sinks. Correlation analysis show, SRP in Fu river may come from dissolved non-reactive phosphorus degradation, organic matter mineralization, phosphobacteria decomposition and the release of Fe/Al-P and Ca-P from sediment; The majority of SRP in Nan river come from dissolved non-reactive phosphorus degradation. The profiles of SRP and DHP have the same trend as TDP in two rivers, indicating that sediment has strong reservation capability of dissolved phosphorus. N/P in two rivers are too higher than Redfield value, and belongs to P-type river.3 The total phosphorus content in sediment: In Fu river, range from 1.69mg/g to 2.53mg/g, IP and OP accounted for 92%, 5% separately. Phosphorus species order is TP>IP>Ca-P>Fe/Al-P>OP>Lsor-P>Ref-P; In Nan river, range from 1.32mg/g to 2.40mg/g, IP and OP accounted for 73.7%, 8.6% separately, Phosphorus species order is TP>IP>Ca-P> Fe/Al-P>Ref-P>OP>Lsor-P. Sedimentary phosphorus in Fu river is almost completely extracted by chemical reagents, While in Nan river, A small fraction of Ref-P exist, which may come from solid waste, Settlement of air particles, indicating that sewage and industrial wastewater discharge have major impact on water pollution.4 The process of phosphorus deposition is different between Fu and Nan river. In Fu river, the content of Sedimentary phosphorus declined gradually and maintained steady subsequently, suggesting that pollution sustained in recent years, and significant amount of pollutants accumulated in the surface by biochemical sedimentation. The main fractions in sediment were sequestered as inorganic phosphorus. IP were dominated by Fe/Al-P and Ca-P. Correlation coefficients show there exists mutual conversion between them; Nitrogen and phosphorus probably come from dissolved organic matter; Ammonium ion exchange is available for the release of Lsor-P and Ca-P, NN-N inhibit phosphorous release from sediment; NN-N substituted oxygen as electron acceptors, the reaction of phosphorus absorption would happen, which accelerate the transference of phosphorus from water to sediment; thiobarillus facilitate phosphorus sorption and Ca-P dissolution, but not help organic phosphorus degradation; Sufur and phosphorus non-homolgy; ES is conductive to the degradation of dissolved non-reactive phosphorus, and PS help Ca-P formation.In Nan river, sedimentary Phosphorus accumulated gradually and reached the highest at -11cm, afterwards, it declined, which is the reflection of phosphorus combination stability, and easily sediment-desorption of phosphorus at deeper layers. Sedimentary phosphorus including Ca-P, Fe/Al-P, OP is an integral part of impact on total phosphorus distribution. Correlation of OP, Fe/Al-P, Lsor-P was high, Correlativity between soluble phosphorus species and sedimentary phosphorus was low, Ca-P was weakly correlated with TP, which reflecting the characteristics of Nan river water environment Experienced a greater change. Organic matter mineralization is the control mechanism on the distribution of OP, Lsor-P, Fe/Al-P. The redox of iron and manganese have effect on phosphorus species. Dissolved organic matter is the source of nitrogen and phosphorus; Adsorption on ammonium ion, NN-N for phosphorus release inhibition, and Nitrate as electron acceptors to decompose organic compounds may exist. Sufur and phosphorus homology; Fe/Al-P, OP, Lsor-P is affected by TRS; dissolved phosphorus species is likely transformed into Lsor-P as AVS formation; ES, PS may accelerate the transformation of dissolved non-reactive phosphorus to inorganic phosphorus; and inhibit the release of Fe/Al-P and OP from sediment; incomplete oxidation of sulfides exist. Four types of bacteria (thiobarillus, nitrobacteria, denitrobacteria, phosphobacteria) decompose OP in sediment or water; Denitrobacteria also help the release of Fe/Al-P from sediment; Lsor-P was susceptible to desorption with thiobarillus and denitrobacteria decomposition; Bacteria biomes decomposition on phosphorus deposition was significant.