源头农业区不同类型水塘中水体沉积物磷吸附容量

湖泊和湿地沉积物性质受到其所在流域土地利用的显著影响.本实验以一个源头小流域的水塘系统为例,研究了位于不同土地利用中的水塘沉积物磷吸附特征.由于水塘分散于不同土地利用中,接收来自于不同土地利用的径流和土壤颗粒,水塘系统提供了研究磷吸附性质的极好范例.研究表明:水塘沉积物具有强的磷吸附容量.吸附最大值(S_max)为228～974mg·kg^-1,平衡浓度(EPC0)为0.004～0.032mg·L^-1,平均饱和度(DPS)仅为9.5%.水塘周围土地利用明显影响沉积物物理化学性质和吸附性质.对于S_max,周围土地利用为林地的山塘最大,而周围土地利用为村庄的村塘最小,其顺序为山塘>旱塘>田塘>河塘>村塘.对于EPC_O则正好相反,山塘<旱塘<田塘<河塘<村塘.分析表明,草酸浸提态铁(Fe_ox)同磷吸附最大值S_max具有显著正相关关系(r²=0.85,p<0.001),而KCl浸提态磷(KCl-P)同平衡浓度EPC_O具有显著正相关关系(r²=0.83,p<0.001).多重回归分析表明草酸浸提态铁(Fe_ox)和KCl浸提态磷(KCl-P)是控制水塘沉积物磷吸附的关键因子.

Phosphorus Sorption Capacities of the Pond Sediments in a Headstream Agricultural Watershed

The land uses in watersheds have important influence on the sediments of lakes and wetlands. Field and laboratory experiments were conducted to research the phosphorus adsorption by the pond sediments in the pond system in a headstream watershed. Being scattered in different ambient land uses and receiving soil particles from various sources, the pond system provides an excellent research example for the phosphorus sorption characteristics. It was found that the pond sediments had strong phosphorus sorption capacities. The phosphorus adsorption maximum (S_max) ranged from 228 to 974 mg·kg^-1, equilibrium phosphorus concentration (EPC_O) ranged from 0.004 to 0.032mg·L^-1. The mean degree of phosphorus saturation (DPS) of the pond sediments was only 9.5%. The situation of the ponds can influence the physico-chemical properties of sediments and their sorption characteristics. For S_max, Hill pond >Nonirrigation pond> Rice pond> River pond> Village pond. On the contrary, for EPC_O, Hill pond< Nonirrigation pond< Rice pond< River pond< Village pond. The phosphorus adsorption maximum (S_max) was significantly correlated with the oxalate-extractable Fe (Fe_ox,r²=0.83, p<0.001), and the equilibrium phosphorus concentration (EPC_O) was significantly correlated with the KCl-extractable phosphorus (KCl-P,r²=0.83, p<0.001). Multiple regression analysis shows that Fe_ox and KCl-P are the key factors, which can influence phosphorus sorption of the pond sediments.