Unraveling the\nBehavior of Stormwater Runoff at Interception\nFacilities: An Explicit Focus on Dissolved Organic Matter with Analytical\nMeasurement

Interception facilities are essential for managing stormwater\nrunoff\nbefore discharge into natural water bodies. This study examines water\nquality and dissolved organic matter (DOM) characteristics under rain\nand nonrain conditions using physicochemical analysis and EEM-PARAFAC\nmethods. Kernel PCA revealed that 76.88 and 71.46% of variance during\nrain and nonrain conditions, respectively, were explained by the first\ntwo principal components. Rain-driven variability was influenced by\nBOD, DO, and EC, while DOM components such as BIX, pH, and C3 were\ncritical during nonrain periods. Two-dimensional correlation spectroscopy\n(2D-COS) analysis indicated new DOM production (C1) and microbial\nhumic-like substances (C2) dominated rain events, whereas microbial\nhumic-like substances (C1) led during nonrain periods, followed by\ntryptophan-like and terrestrial humic-like components, obeying the\nsequence C1 → C2 → C4 → C3 by Noda’s rule.\nScanning electron microscopy (SEM) analysis showed suspended solids\nhad the most negative impact on water quality during rain (−0.90),\nwhile fresh DOM positively influenced organic matter (FI: 0.94, BIX:\n0.78), in contrast to recalcitrant humic substances (C4: −0.96).\nThese findings underscore the role of interception facilities in mitigating\npollutant loads, particularly suspended solids and nutrients, and\nhighlight their importance in managing stormwater and regulating DOM\ndynamics across hydrological conditions.