Synthetic phenolic antioxidants in paddy soils from central China: Contamination characteristics and risk prioritization analysis

Abstract

The contamination characteristics and ecological risks of synthetic phenolic antioxidants (SPAs) in agricultural soils remain poorly understood. In this study, 20 SPAs and 4 of their transformation products were analyzed in paddy soils from the Dongting Lake Basin in central China. The median total concentration of the 20 SPAs (Σ₂₀SPAs) was 147 ng/g (range, 27.6–612 ng/g), while their transformation products had a median concentration of 127 ng/g (range, 36.4–625 ng/g). Among the target compounds, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate) (Ir1010), and 2,6-di-tert-butyl-4-methylphenol (BHT) were identified as the predominant contaminants. Spatial distribution analysis revealed that certain sites in the eastern Dongting Lake Basin exhibited notably higher concentrations of transformation products compared to other areas, indicating potential regional variability in the transformation behavior of SPAs. Furthermore, the detected SPAs and their transformation products posed potential ecological risks to paddy soil ecosystems, with cumulative risk quotient values reaching up to 23.6. The toxicological priority index values of Ir1010 and 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diylbis(2-methylpropane-2,1-diyl)bis(3-(3-(tert-butyl)-4-hydroxy-5-methylphenyl)-propanoate) (Ir80) ranked relatively high (0.61 and 0.53, respectively), warranting greater attention. This study provides new insights into the co-occurrence of SPAs and their transformation products in paddy soils, and underscores the complex environmental risks associated with these emerging contaminants.