Preliminary study on phosphorus release of internal load in Dianchi Lake sediment

In an investigation on redistribution of semimetal phosphorus and the internal load of phosphorus in Dianchi Lake, more than 20 undisturbed sediment-water cores have been sampled. The concentrations of total phosphorus, total nitrogen, organic carbon in sediment samples, and dissolved phosphorus have been analyzed. The dissolved total phosphorus both in water samples and pore water samples have been compared. The internal load of phosphorus has been calculated in terms of release fluxes of phosphorus from sediment by using Fick's law. The exchange of phosphorus between sediment-water-interface in some undisturbed sediment-water cores has been tested in laboratory and compared with the theoretical calculation. The study shows that the release flux of phosphorus from sediment ranged from 0.018 to 0.418mg/cm~2/a with average value of 0.095mg/cm~2/a. The study also indicates that the regeneration and release of sediment phosphorus in this lake could arise due to organic materials degradation. The conversion of organic forms of phosphorus in sediment is consideredas the main reason of phosphorus release.