底泥氮磷释放的空间异质性及其环境驱动因素分析——以城市中小河流为例

Spatial Heterogeneity and Environmental Drivers of Nitrogen and Phosphorus Release from Sediments—Focusing on Small and Medium-Sized Urban Rivers

摘要: 本文选取了9条重要河道(水库)作为研究对象，布设22个监测点位，检测其水体和底泥的理化参数(DO、NH₄-N、TN、TP等)，并开展室内氮磷静态释放实验，结合综合污染指数(FF)评价底泥污染程度，运用聚类分析和Pearson相关性解析影响因素，探讨河流底泥氮磷释放的时空特征及其关键影响因素，以期为流域内源污染治理提供依据。结果表明：9条河流水体指标呈现显著空间异质性，22个样本中，S22卫星水库水体DO浓度最低(0.44 mg/L)，S18大溪河水体NH₄-N和TN浓度最高(分别为6.13 mg/L和8.51 mg/L)，指示严重富营养化特征；底泥总氮的浓度在648.30~3849.63 mg/kg之间，总磷的含量在171.25~1073.10 mg/kg之间，含量较高，综合污染指数(FF)显示27.3%的样本处于重度污染状态；静态释放试验表明，R7-大溪河和R6-桥溪河的氮磷释放速率显著高于其他河流，其中R7-大溪河的TN释放速率高达317.1 mg/(m²·d)，聚类分析显示，底泥特性、上覆水DO、外源污染输入是影响底泥氮磷释放的主要因素。

Abstract: This study selects nine significant river channels (reservoirs) as research subjects, establishing 22 monitoring stations to assess the physicochemical parameters (such as DO, NH₄-N, TN, TP) of their water bodies and sediments. Additionally, indoor static release experiments for nitrogen and phosphorus were conducted. By utilizing the comprehensive pollution index (FF) to evaluate the level of sediment pollution, combined with cluster analysis and Pearson correlation analysis to dissect the influencing factors, this study explores the spatiotemporal characteristics and key drivers of nitrogen and phosphorus release from river sediments, aiming to provide insights for the management of endogenous pollution within watersheds. The findings revealed notable spatial heterogeneity among the water quality indicators of the nine rivers. Specifically, among the 22 samples, the S22 satellite reservoir exhibited the lowest DO concentration (0.44 mg/L), while the S18 Daxi River demonstrated the highest NH₄-N and TN concentrations (6.13 mg/L and 8.51 mg/L, respectively), indicating severe eutrophication. The total nitrogen concentration in the sediments ranged from 648.30 to 3849.63 mg/kg, and the total phosphorus content ranged from 171.25 to 1073.10 mg/kg, both of which are relatively high. According to the comprehensive pollution index (FF), 27.3% of the samples were in a state of severe pollution. Static release experiments demonstrated that the nitrogen and phosphorus release rates of the R7 Daxi River and R6 Qiaoxi River were significantly higher than those of other rivers, with the TN release rate of the R7 Daxi River reaching as high as 317.1 mg/(m²·d). Cluster analysis indicated that sediment characteristics, dissolved oxygen (DO) in the overlying water, and external pollution inputs were the primary factors influencing the release of nitrogen and phosphorus from the sediments.