Synthetic antioxidants in Chinese urban green Spaces: From emerging contaminants to environmental and public health risks

Synthetic antioxidants (SAOs) as emerging environmental contaminants have garnered increasing attention. Urban park soils constitute significant reservoirs for pollutants; however, understanding of the occurrence characteristics, potential sources, and risk implications of SAOs in these matrices remains limited. This study presents the first investigation of 13 traditional and 44 novel SAOs in urban park soils across Guangzhou, Shijiazhuang, and Ürümqi, China. All target SAOs were detected, with detection frequencies spanning 1.8%–100%. Total SAO concentrations exhibited a wide range of 231.6–21,477.2 ng/g (median: 3487.0 ng/g), with BHT-CHO, DTPD, and 6PPD identified as the dominant contributors, and novel SAOs dominated the contamination profile at most sites. Although regional variations occurred in individual SAO concentrations, the overall pollution burden exhibited spatial homogeneity across the three cities. Potential sources were inferred as TWPs-derived pollution sources, industrial emissions or specialized rubber product sources, degradation-related sources, multimodal contamination sources, and specialized industrial additive sources. The estimated ecological risk quotient of BHT-CHO and the selected SAOs mixture were more than 1.0, whereas the potential health risks to children and adults were relatively low. This study advances understanding of environmental exposure in urban green spaces and provides a scientific basis for targeted mitigation strategies to reduce ecological impacts and human exposure.