Release characteristics of sediment phosphorus in all fractions of West Lake, Hang Zhou, China

The release characteristics of sediment phosphorus (P) in all fractions under varying environmental factors: P concentration in overlying water, light, pH, temperature and agitation intensity in shallow city lake West Lake, Hang Zhou, China were investigated. The release quantity and release rate of sediment P in the distilled water were significantly higher than that of lake water, and the maximum release quantity of sediment P in irradiated conditions was lower than that without irradiation. P release from the sediments occurred in both acidic and alkaline conditions, acidic condition was more favorable, and neutral condition was the least favorable. The released amount of each P forms changed variously with the temperature increasing, and various P fractions content in the sediment decreased sharply comparing to static conditions after strong disturbing. The logarithm values of released amount of sediment P were linear with the logarithm values of time, and the fitted release kinetics curves could be described well by exponent kinetic model: lnq = b + klnt. The results showed that the extent of P in all fractions release from West Lake sediment were affected variously by the environmental factors, and the sediment was unstable, at risk of releasing P to West lake.