Distribution Characteristics and Risk Assessment of Typical Rubber Additives and Their Transformation Products in the Guangzhou Section of the Pearl River, China

• • Total concentrations of seven rubber additives and 6PPD-Q in the Guangzhou section of the Pearl River ranged from 205 to 5400 ng·L−1 (mean 820±1100 ng·L−1), indicating substantial contamination levels that warrant monitoring and mitigation. • • DPG dominated both dissolved (99±1.9%) and particulate (66±13%) phases, underscoring its role as a primary pollutant and its potential for widespread aquatic transport. • • 6PPD-Q exhibited high ecological risk (RQ > 1) at all 29 sampling sites, while DPG showed moderate to high risk (RQ > 0.1) at most sites, necessitating priority action for these compounds. • • Source apportionment linked contamination to aquaculture, vessel navigation, agricultural land, and wastewater treatment plant discharges, providing actionable targets for pollution control strategies.