Stormwater runoff acts as a vital intermediate between wet precipitation, terrestrial, and aquatic ecosystems, in which chromophoric dissolved organic matter (CDOM) plays an important role in influencing the transport, toxicity, bioavailability, and ultimate fate of many pollutants. It is important and necessary to characterize the CDOM in stormwater runoff, which is useful to clarify the relationship between CDOM with the other coexisting organic and/or inorganic components. In this study, 30 stormwater runoff samples were collected from three different stormwater events in a typical residential area in Beijing, and CDOM in the samples was characterized by UV–visible spectroscopy, excitation–emission matrix fluorescence and proton nuclear magnetic resonance (¹H NMR) spectroscopy to investigate its compositions, structures, and sources. Being compared to the previous studies on wet precipitation, average molecular weight of CDOM in this study was much larger, implying the presence of more aromatic components with carbonyl, carboxyl, hydroxyl and unsaturated carbon atoms functional groups. Furthermore, both allochthonous and autochthonous sources contributed to the local CDOM, and their chemical properties were influenced by anthropogenic and biogenic factors. Thus, the CDOM in stormwater runoff is a compositionally different matrix than that discovered in wet precipitation.

Organic fertilizers are rich in nutrients but also frequently contain multiple contaminants that pose a potential threat to the agricultural environment. However, comprehensive investigations into commercial organic fertilizers remain scarce. In this study, 54 commercial organic fertilizer samples—including animal manure-based fertilizers, BOF (bio-organic fertilizer), and other types of fertilizers—were systematically investigated. For OM (organic matter), 48.15% of samples fell below the 30% w/w threshold specified by the industry standard NY/T 525-2021. The exceedance rates of Cu and Zn across all fertilizers were 14.81% and 12.96%, respectively, relative to the German Biowaste Ordinance (BioAbfV) limits. Differences in properties among geographic origins were less pronounced than those among fertilizer types. Pig manure-based fertilizers had the highest nutrient contents, especially phosphorus, but also the highest levels of contaminants, including antibiotics, heavy metals, antibiotic-resistant bacteria (ARB), and antibiotic resistance genes (ARGs). BOF exhibited the best overall quality, with a total nitrogen content 2.0–4.4 times that of the manure-based fertilizers, together with higher organic matter and lower contaminant levels. This study establishes a comprehensive baseline for commercial organic fertilizers in China, providing critical empirical evidence for future industry governance and fertilizer management.