北运河沙河水库沉积物营养盐分布特征及其溯源分析

Nutrients distribution and its sources analysis of sediments in Shahe reservoir of Northern Canal

通过采集沙河水库表层(0～20 cm)沉积物样品,分析了沉积物中氮、磷、有机质的分布特征,并结合排污口附近和水库典型区域沉积物中有机质(Organic Matter, OM)和溶解性有机物(Dissolved Organic Matter, DOM)的荧光光谱特征、分子量分布特征(Molecular Weight Distribution, MWD),研究了点源污染对沙河水库沉积物营养盐分布的潜在影响.结果表明,表层沉积物间隙水中氨氮(NH^+_4-N)、磷酸盐(PO■-P)平均浓度及沉积物中总氮(TN)、总磷(TP)的平均含量依次为(52.13±40.32)、(1.75±1.88) mg·L^(-1)与(2853.81±1501.93)、(1496.00±454.06) mg·kg^(-1).库区沉积物中TN、TP含量由库上游((1898.00±1047.54)、(1264.00±104.61) mg·kg^(-1))经库心区((2996.67±1405.13)、(1340.00±332.47) mg·kg^(-1))至库下游((4500.00±920.00)、(1750.00±10.00) mg·kg^(-1))依次增高.沉积物C/N比分析表明,点源污染区与库区沉积物中有机质来源于陆源与自生生物源的混合源.而三维荧光光谱和分子量分布的分析表明,点源污染区与库区沉积物中DOM的组成特性具有一致性,且主要来源于自生生物源.Pearson相关性分析表明,沉积物中营养盐(TN、TP)与有机质具有显著相关关系(p<0.01).这些结果清楚地表明,点源污染区沉积物中高的营养盐、有机质含量是库区污染物累积的潜在重要来源.

This study carried out investigating distribution of nutrients and organic matters, as well as the source analysis in the surface sediments(0~20 cm) of Shahe reservoir. Through characterizing 3 D-EEM and molecular weight of organic matter(OM) and dissolved organic matter(DOM) in the sediment, the potential effect of point source pollution on the nutrients distribution was discussed in this study. Results showed that the average concentrations of ammonia(NH4^+-N) and orthophosphate(PO4^3--P) in the interstitial water were(52.13±40.32),(1.75±1.88) mg·L^-1, and those of total nitrogen(TN) and total phosphorus(TP) in the surface sediment were(2853.81±1501.93),(1496.00±454.06) mg·kg^-1, respectively. The concentrations of TN and TP in the sediment increased in the order of the upstream((1898.00±1047.54),(1264.00±104.61) mg·kg^-1), the reservoir center((2996.67±1405.13),(1340.00±332.47) mg·kg^-1) and the downstream((4500.00±920.00),(1750.00±10.00) mg·kg^-1). The C/N ratio of the sediment indicated that the organic matter in the sediments of the point source pollution area and reservoir is derived from the complex sources of terrestrial plants and aquatic organisms. And the results of 3 D-EEM and molecular weight distribution showed that the characteristics of DOM in sediments in both the point source pollution area and the reservoir area were similar, which mainly derived from the aquatic organisms. Results of the Pearson analysis showed that the distribution of nutrients(TN, TP) in sediments significantly correlated to organic matters(p<0.01). Therefore, based on these above mentioned results, point source pollution is an important potential contamination source for the accumulation of nutrients and organic matters in Shahe reservoir.