Experimental studies on salt exchange between freshwater and sediments in a polder reservoir

Based on the field investigation and drilling,three kinds of original/disturbed sediments and the local surface water were sampled around the Muguandao Reservoir.Then,the temporal-spatial variation in salinity was measured carefully through the column and tank tests.At last,the salt fluxes released from the deposits were calculated.This research lays a scientific foundation for the evaluation and prediction of the water quality in the reservoir.According to the column tests,it is found that a 7.5 cm high salinity zone is formed near the interface due to molecular diffusion,and the salt concentration is relatively low and homogeneous above that level.In addition,the salt released fluxes can be expressed as the negative exponential functions, and they decrease in order of the silty clay,the medium-fine sand and pelitic silt.The tank tests show that wind may influence the salt stratification above the interface,which is favorable to salt mixture in the reservoir.