风干和淹水过程对巢湖流域土壤和沉积物磷吸附行为的影响

EFFECT OF AIR-DRYING AND FLOODING ON PHOSPHORUS SORPTION BEHAVIOR OF SOILS AND SEDIMENTS ALONG THE AQUATIC-TERRESTRIAL ECOTONE OF LAKE CHAOHU

巢湖湖滨带土壤和沉积物经历明显的干湿交替过程,其磷的迁移和转化方式亦有明显变化。风干作用能显著降低沉积物磷最大吸附量、提高吸附能并增加磷平衡浓度,从而对磷的吸附能力产生不利影响。淹水过程对土壤最大吸附量的影响取决于有机质的损失情况,好氧条件下有机质损失小,磷最大吸附量无明显变化,吸附能增强,磷释放量略有增加;而厌氧条件下土壤有机质含量与磷最大吸附量均显著降低,吸附能明显减小,磷释放量显著升高。因此湖滨带消落区干湿交替将明显促进底质生物可利用性磷的大量释放。在巢湖流域常见的土壤类型中,红壤对磷的缓冲能力最强。向底质中添加氯化铁和硝酸钙可有效控制磷释放,提高磷缓冲能力,增强底质对磷的保持和固定。

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.