Phosphate Adsorption Characteristics on Surface Sediments of Nansi Lake and Its Main Inflow Rivers
南四湖及主要入湖河流表层沉积物对磷酸盐的吸附特征

Adsorption capacity, isotherms and kinetics of phosphate onto the 18 surface sediments taken from Nansi Lake and its main inflow rivers were investigated in laboratory, and the relationships between physical and chemical properties of the sediments and their phosphate adsorption characteristics are discussed. The results indicate that the phosphate adsorption characteristics of sediments that are at different trophic levels are similar. The amount of phosphate adsorbed within 10 h almost reaches or exceeds 80% of the maximum adsorption of phosphate and the maximum adsorption rates occur within 0-1.0 h. C(EPC) ranges from 0.010 to 0.157 mg x L(-1), Q(max) from 86.74-118.32 mg x kg(-1), and TQ(max) from 99.97-281.11 mg x kg(-1) in the study. Between Ads-P and its c(EPC), NAP, m, Q(max) and TQ(max) have remarkable positive correlation. The content of Ads-P will serve as a index indicating the polluted level in Nansi Lake. Adsorption efficiency (m) has remarkable positive relationship with TQ(max). The m is the sum of adsorption efficiency of the sediments adsorbing the phosphorus coming from external and the phosphorus desorbed from the sediments. The NAP has positive correlation with c(EPC) and the trend is that the sediment with higher NAP easily desorbs phosphorus to the water, contrarily the sediment with lower NAP easily adsorbs phosphorus.