巢湖十五里河不同水力特性区沉积物及间隙水营养盐的分布特征

为揭示水力特性对小河流沉积物及间隙水中氮磷营养盐分布特征的影响,在巢湖十五里河河道上,选择支流交汇处、弯道淤积处、弯道冲刷处、河岸坍落处、水生植物生长区、平直河段、河内浅滩等7种水力特性类型,采集深度约40cm的沉积物柱状样,并按2cm厚度现场分层,得到136个样品.在实验室分析测试的基础上,解析沉积物与间隙水氮磷垂直剖面特征及沉积物-上覆水界面氮磷营养盐的源/汇关系,拟合间隙水剖面NH＋4-N、NO-3-N和PO3-4-P浓度,并对采样点位进行聚类分析.研究结果表明：不同水力特性区沉积物氮磷含量差异明显;弯道冲刷处和河岸坍塌处间隙水剖面NH＋4-N、NO-3-N和PO3-4-P浓度相对较低,且垂直变化不大,但在水生植物生长区则变化明显;不同水力特性区的水-土界面NH＋4-N、NO-3-N源/汇关系,具有很好的一致性,而PO3-4-P则差异明显;在沉积深度0～16cm范围内,除水生植物生长区外,其它各水力特性区间隙水NH＋4-N、NO-3-N和PO3-4-P浓度在垂直剖面基本上都可以借助指数函数y=exp（a＋bx＋cx2）拟合,这与湖泊、水库等宽阔水域存在一定差异.

Distribution characteristics of nutrients in core sediments and interstitial water from different hydraulic property zones in Shiwuli Stream, Chaohu Lake

To investigate the effects of hydraulic properties on nutrient concentration profiles of sediment and interstitial water in stream/creek, seven types of hydraulic characteristic zones were chosen in the Shiwuli Stream, Chaohu Lake. The core sediments about 40 cm thick were collected in each characteristic zone and sliced in-situ with a thickness of 2 cm, and then a total of 136 samples was obtained. According to the measured data, the vertical profiles of nitrogen and phosphorus contents both in sediment and interstitial water were illustrated, and the cluster analysis was carried out for the sampling sites. Moreover, the source-sink relationship of each of NH₄⁺-N, NO₃^--N and PO₄^3--P at the sediment-overlying water interface was explored and their vertical concentration profiles in interstitial water were modeled as well. Study results show that there are significant differences both in the nutrient content levels and distribution characteristics in sediments for the seven hydraulic characteristic zones. There are lower concentrations and inconsiderable vertical variability for NH₄⁺-N, NO₃^--N and PO₄^3--P in interstitial water in both the erosion zone on the bend and bank failure zone, but a remarkable variation characteristic was present in the growing zone of aquatic plants. At the sediment-overlying water interface, there is a good agreement on the source-sink relationship of nutrients except PO₄^3--P, and within the depth of 0~16 cm, the concentration profiles of nutrients in interstitial water can be modeled by using exponential function y=exp(a+bx+cx²) except for the growing zone of aquatic plants, which is different from the lake or reservoir waters.