持续干燥对消落带沉积物磷形态和吸附特征的影响

EFFECTS OF CONTINUOUS DRYING ON PHOSPHORUS FORMS AND ADSORPTION CHARACTERISTICS IN SEDIMENTS OF HYDRO-FLUCTUATION BELT

以澜沧江流域功果桥库区消落带沉积物为研究对象,研究了持续干燥状态下磷形态和等温吸附变化特征。结果表明:持续干燥对磷和铁形态有显著影响,弱吸附态磷(NH_4Cl-P)、铝结合态磷(NaOH-rP)无机磷(IP)和结晶度较高的碳酸盐铁(Carb-Fe)含量增加,而可还原态磷(BD-P)、聚磷/有机磷(NaOH-nrP)和还原铁氧化物(Ox-Fe)含量减少;沉积物等温吸附特征也有显著变化,最大吸附磷酸盐总量(Q_(max))和吸附系数下降,表明重复短暂的湿润和干燥周期会导致磷的沉积亲和力不断下降,从而增加沉积物内源磷向水体释放的潜在性。

The phosphorus forms and isothermal adsorption characteristics in sediments collected in hydro-fluctuation belt of Gongguoqiao Reservoir Area, Lancang River Basin, were studied under continuous drying condition. The results showed that: continuous drying had significant effect on the phosphorus and iron forms, the contents of weakly adsorbed phosphorus(NH4Cl-P), aluminum-bound phosphorus(NaOH-rP), inorganic phosphorus(IP) and carbonate iron(Carb-Fe) with high crystallinity increased, while contents of reducible phosphate(BD-P), polyphosphate/organophosphate(NaOH-nrP) and reductive iron oxide(Ox-Fe) decreased;the isothermal adsorption characteristics of the sediments also changed significantly, and the maximum total amount of phosphate adsorbed(Qmax) and adsorption coefficient decreased, which indicated that repeated short periods of wetting and drying would lead to continuous decline of phosphorus deposition affinity, thus increasing the potential release of endogenous phosphorus into water.