[Effect of inactivation agents on the phosphorus release from sediment of Lake Dianchi at different temperature]

The influence of temperature on P release from sediment of Lake Dianchi was discussed. Two kinds of inactivation agent schemes (Al2SO4.18H2O and PAC-Polymeric Aluminum Chloride) were used. The results show that the P release amount from sediment increased as the environmental temperature increased. As temperature raised 10 degrees C, the TP release amount increased 1.22%-38.69%, the DTP release amount increased 4.79%-76.82%. From 25 degrees C to 35 degrees C, the sediment had the largest P release increment. When temperature rose, the oxygen demand in the overlying water increased. Then the transformation speed of Fe3+ to Fe2+ increased, and then the release of Fe-P in sediment accelerated. On the other hand, microbe activity made the release possible through the transformation from organic-phosphorus to inorganic-phosphorus. The inactivation agents used here have significant effect on restraining the phosphorus release from sediment and the capture of particles containing phosphorus in overlying water. PAC had better P inactivation effect than Al2SO4 at 25 degrees C. Inhibition rate of P release from sediment by PAC was about 0.49%, 1.32%, 1.03% higher than Al2SO4 at 5, 15 and 25 degrees C, respectively. As the temperature rose to 35 degrees C, the capacity that PAC restricted P was weakened, so the effect of P release inhibition was weakened. Inactivation rate of Al2SO4 was higher about 2.25% than PAC to P from sediment at 35 degrees C. Temperature of sediments in PAC sets is 2-3 degrees C lower than that of Al2SO4 sets.