Migration And Transformation Of Phosphorus And Heavy Metal In Sediments In Drinking Water Reservoir

Released nitrogen, phosphorus and heavy metals from sediments are one of themost outstanding problems facing water reservoir. Based on water reservoirs of greatdepth as the main research object, method of laboratory simulation was adopted tosimulate the conditions on overlying water interface in water reservoir, such as lowdissolved oxygen, REDOX conditions, poor nutrition, and etl. Under this simulatedconditions, effects of environmental factor and microbial on phosphorus release wasstudied, the migration of heavy metals such as iron, aluminum, manganese wasresearched, correlation between phosphorus and heavy metals was discussed. Thecrucial results and conclusions are as follows:(1) Effects on the release of sediment phosphorus in overlying water in drinkingwater reservoir: water reservoir in overlying water interface: reducing DO, ORPoxygen and microbe were the decisive factors for the overlying water environment intoanaerobic reductive condition. Mass release of phosphorus in the sediment werepromoted by the strong reducing conditions which oxidation reduction potential (ORP)<0mV, concentration of TP, PO43-in overlying water were increased, whichaccompanied by a large number of Fe2+into the overlying water. Sediment release ofphosphorus is given priority to Fe/Al-P and IP, most of the PO43-migration into theoverlying water, which occupied more than50%of the released TP in overlying water.The decomposition and transformation of OP was promoted by the microbial activityin Sediments, phosphorus (except for PO43-) in overlying water were absorbed by themicrobial and finally stored in the sediment.(2)The release of sediment phosphorus on the transformation of sediment iron,aluminum, manganese: under the condition of anaerobic and reduction, sediment Fe/Al-P, IP and Fe-Al-bound phosphorus was largely released into the overlying water,accompanied by the release and absorption of sediment iron, manganese, aluminum,the release of total phosphorus (TP) and total iron (TFe). The release rate respectivelyreached2.038mg,0.649mg·m-2·L-1and0.806mg,0.257mg·m-2·L-1at the same time.The redundancy analysis (RDA) to the overlying water phosphorus, iron, manganese,aluminum and DO, ORP, pH showed that DO is significantly negative correlated withP in overlying water, pH is significantly negative correlated with Al in overlying water,Fe is significant positive correlated with Mn, and Fe、Mn were significantly negativecorrelated with ORP, Al in overlying water is significantly negative correlated with P.(3) Migration translational research of heavy metal in the water reservoir sedimentand overlying water: Cu, Pb, Cd, Zn, As, Hg and other heavy metals were largelyreleased into the overlying water under anaerobic conditions in sediments, whichrepresented respectively with carbonate-bound Cu, residue-bound Pb, carbonate-boundand residue-bound Zn, metal organic-bound and metal exchangeable bound As, metalexchangeable bound, iron (manganese) oxide-bound, residue-bound Hg. Physical andchemical transformation of Cu, As two heavy metal forms would simultaneouslyoccurred, which also existed among Cd, Pb, Zn and Hg four heavy metal forms. Thelower the value of DO, the easier sediment bound of Cu, Zn converted to a ion state,which resulting in the increased concentration of Cu, Zn ions in overlying water; thelower the value of ORP, the easier sediment-bound Pb, Cd, As, Hg are converted to aion state, which also resulting in the increased concentration of Pb, Cd, As, Hg ions inoverlying water.