农业流域中不同类型水塘沉积物磷素状态及其环境意义

The status of phosphorus and its environmental significance in various pond sediments in an agriculture watershed

通过对安徽巢湖六叉河小流域的多水塘系统进行采样和分析,测定了流域中不同类型水塘沉积物磷素赋存形态与分布特征,并对其环境意义进行了探讨.研究表明,水塘周边土地利用对沉积物磷含量具有重要影响,水塘沉积物全磷(TP)含量在286.3—651.3 mg·kg-1之间,村塘TP含量显著高于其他类型水塘,基本表现为村塘>河塘>山塘≈旱塘≈田塘;在TP中,铁铝结合态磷(Fe/Al-P i)和惰性磷(Residual P o)占主要地位(Fe/Al-P i,44.28%;Residual P o,37.74%),钙镁结合态磷(Ca/Mg-P i)和活性有机磷(Hu/Fu acids-P o)比例相对较小(Ca/Mg-P i,8.50%;Hu/Fu acids-P o,9.37%),易解吸磷(Exch-P i)所占比例最小,各水塘均不到0.20%;TP中的活性组分如Exch-P i、Fe/Al-P i、Hu/Fu acids-P o以及有效磷(Olsen P)、草酸浸提态磷(Ox-P i)等同TP均具有显著的正相关性(P<0.01),其他组分如Ca/Mg-P i和Residual P o与TP相关性不显著,水塘沉积物活性磷组分主要受控于外源输入,在水塘沉积物富磷化的同时,沉积物磷素的流失风险和潜在的生物可利用性均显著提高,因此在多水塘系统中,对水塘尤其是村塘的及时挖掘和疏浚是非常重要的.

Phosphorus status and its environmental significance in various pond sediments of the muhipond system were analyzed in Liuchahe watershed in Chaohu Lake watershed. Results showed that the ambient land uses had important effects on the properties of the pond sediments. The contents of total phosphorus （TP） were within the scope of 286.1-651.3 mg. kg^- 1. TP content of the Village pond sediment was significantly higher than those of other pond types. The order was Village pond 〉 River pond 〉 Hill pond . Nonirrigation pond Rice pond. The Fe/Al-bound phosphorus （Fe/Al-Pi ） and resistant organic phosphorus （Residual Po ） were the dominant pools of TP （Fe/Al-Pi, 44.28% ; Residual Po, 37.74% ）. The percents of Ca/Mg-bound phosphorus （Ca/Mg-Pi ） and reactive organic phosphorus （Hu/Fu acids-Po） were relatively low （Ca/Mg-Pi, 8.50% ; Hu/Fu acids-Po, 9.37% ）. The labile pool of Pi （Exch-Pi） had the lowest percentage of TP （Exch- Pi, 0. 11% ）. There were significantly positive correlations between TP and the reactive phosphorus pools, such as Exch-Pi, Fe/Al-Pi and Hu/Fu acids-Po, as well as the available phosphorus （Olsen P） and oxalate- extractable phosphorus （Ox-Pi）. With the increase of TP, the reactive phosphorus pools in pond sediments increased linearly, also the risk of phosphorus loss and potential bioavailability increased significantly. It is necessary to dig the sediments of ponds in time, especially the Village pond.