Characteristics of Phthalic Acid Esters Pollution in Urban Surface Runoff in Shanghai, China

Abstract

Phthalic acid esters (PAEs) are still widely applied in China, and their pollution characteristics in urban surface runoff are important to receiving water protection. To evaluate the pollution characteristics of PAEs in urban runoff, six priority PAEs in road and roof runoff were monitored in nine storm events from June to September 2017 in Shanghai, China, and related rainwater samples were collected simultaneously. The average ∑6PAEs in urban road and roof runoff were 170.64 μg·L-1 and 40.92 μg·L-1, respectively, much higher than the values reported in Europe and Australia. Di-2-ethylhexyl phthalate (DEHP) was the dominating pollutant in both road and roof runoff. Significance analyses indicated there was no significant difference for low molecular weight(LMW)PAEs concentrations between road and roof runoff, whereas high molecular weight (HMW) PAEs concentrations in road runoff were significantly higher than those in roof runoff and rainwater (P<0.01), which implied that traffic was an important factor contributing to PAEs pollution in urban runoff. The pollutograph of PAEs, total suspended solids (TSS), and chemical oxygen demand (COD) concentrations vs rainfall duration for road runoff showed the same trend, and the first flush effect of PAEs was generally apparent. The influencing factors of PAEs in urban runoff were investigated. EMCs of PAEs in roof runoff were negatively correlated with rainfall intensity and positively correlated with TSS. EMCs of PAEs in road runoff were negatively correlated with rainfall volume and intensity and positively correlated with antecedent dry period, TSS, and COD. PAEs in surface runoff were significantly correlated with particulate matter. According to the criteria of the National Standard of Surface Water Quality of China, DEHP and DBP have limiting values of 8 μg·L-1 and 3 μg·L-1, respectively. The ratios of DEHP concentrations in road and roof runoff to the limiting values are 32 and 7, respectively. DBP concentrations were higher than the limiting value in most rainfall events for road runoff but lower than those for roof runoff. Without reasonable management measures, urban runoff could contaminate receiving water, especially drinking water sources.