Effect of air-drying and flooding on phosphorus sorption behavior of soils and sediments along the aquatic-terrestrial ecotone of lake chaohu

During the course of drying and rewetting that the soils and sediments along the aquatic-terrestrial ecotone of Lake Chaohu experienced time and again,the manner of transport and transformation of phosphorus varied greatly.Air-drying would adversely affect the phosphorus buffering capacity of sediment in terms of the maximum phosphorus sorption capacity decreasing largely and sorption energy and EPC0 increasing.The effect on maximum phosphorus sorption capacity after flooding depends on the loss of organic matter in the soil.In aerobic condition,less loss of organic matter made no significant variation of maximum phosphorus sorption capacity,while sorption energy increased.In anaerobic condition,the maximum phosphorus sorption capacity reduced markedly due to more loss of organic matter,moreover,the sorption energy decreased and phosphorus release increased.In a word,the drying and rewetting behavior in water-level fluctuating zone will accelerate the release of bioavailable phosphorus from substrate obviously.Among the widely distributed soil types in Lake Chaohu drainage area,red soil,whose phosphorus buffering capacity was the strongest containing highest content of organic matter and the least loss after flooding,was suitable for application in remediation of shoreline.Moreover,with additions of FeCl3 and Ca(NO3)2,the phosphorus buffering capacity of substrates was increased and also enhanced the ability of phosphorus retention and fixation.