Effects of inactivation agents and temperature on phosphorus release from sediment in Dianchi Lake, China

The inhibitory effects of three inactivation agents (PHOSLOCK, Al(SO)18HO, and PAC-polymeric aluminum chloride) on phosphorus (P) release from sediment in Lake Dianchi were examined. The influence of temperature on P release was also assessed. We found that at increased temperatures, P release from sediment increased. While the temperature increased by 10 °C, the TP release increased by 13.20–36.98 %, and DTP release increased by 11.14–47.93 %. The concentration of P in overlying water increased with time, which slowed the release of P. P release increased with temperature because the increase in oxygen demand in the overlying water contributed to the release of Fe–P from sediment, and may be due to microbial transformation of P from organic phosphorus into inorganic phosphorus. PHOSLOCK showed significantly greater inhibition of P release and the capture of particles absorbed from phosphorus in overlying water compared to Al(SO) and PAC. The rate of inhibition of P release from sediment by PHOSLOCK was approximately 15.13, 15.20, and 5.13 % higher than that of Al(SO); and 7.03, 9.75, and 10.09 % higher than that of PAC at 15, 25, and 35 °C, respectively. In addition, the inhibitory effect of PAC was greater than that of Al(SO) at 25 °C, while the opposite was true at 35 °C. This may be because lanthanide in PHOSLOCK can react with sulfate radicals to generate precipitate. The precipitate is highly stable, which results in solidification of P in the sediment, which cannot be released.