Impacts of disturbance on release of total nitrogen and total phosphorus from surficial sediments of Dongping Lake.

Surficial sediment samples were collected from Dongping Lake to investigate the impacts of disturbance on release of nutrients elements from surficial sediments.Results showed that no significant impacts could be found for the disturbance on pH of lake water,while the soluble cations increased obviously under the disturbance.There is no significant difference could be found for disturbance intensity of 25 and 50rpm on the accumulative releasing contents and releasing velocity of total nitrogen.Under the disturbance intensity of 100rpm,the accumulative releasing contents and releasing velocity of total nitrogen increased by 5.02mg/kg and 73.5% respectively compared with those of under the static state.Under the disturbance intensity of 25rpm,50rpm and 100rpm,the accumulative releasing contents of total phosphorus increased by 0.185,0.263 and 0.320mg/kg compared to the static state.Releasing velocity of total phosphorus increased by 36.2%,41.7% and 127.6% compared to the static state,which indicated that the disturbance would enhance significantly the release of TN and TP from surficial sediments of lakes.