Multiphase partitioning and risk assessment of endocrine-disrupting chemicals in the Pearl River, China.

Multiphase partitioning of endocrine-disrupting chemicals (EDCs) in the Pearl River (China) were investigated. The colloidal concentrations for 4-tert-octylphenol, 4-nonylphenol, bisphenol A (BPA), and estrone (E1) were in the ranges of 0.2 ng/L to 0.8 ng/L, 23.2 ng/L to 108 ng/L, 2.3 ng/L to 97.6 ng/L, and not detectable (nd) to 0.32 ng/L, respectively; for truly dissolved concentrations, the ranges were 0.5 ng/L to 5.4 ng/L, 39 ng/L to 319 ng/L, 13.7 ng/L to 91.2 ng/L, and nd to 1.2 ng/L, respectively. Positive correlations of EDCs with colloidal organic carbon (COC) were observed. The in situ COC normalized partitioning coefficients (log KCOC ) for 4-tert-octylphenol (5.35 ± 0.42), 4-nonylphenol (5.69 ± 0.50), and BPA (5.51 ± 0.77) were within the ranges reported by other studies, whereas they were 1 to 2 orders of magnitude higher than their particulate/truly dissolved phase partition coefficients (log KOCint), revealing much strong sorption of EDCs by aquatic colloids. Moreover, colloid-bound percentages of 4-tert-octylphenol, 4-nonylphenol, and BPA ranged, respectively, from 6.9% to 36.4%, from 16.7% to 63.1%, and from 3.6% to 52.4%; their estimated mass fractions were 0.29 ± 0.21, 0.38 ± 0.26, and 0.39 ± 0.33, respectively. Obviously the colloid-bound fractions are significant. Furthermore, a medium risk of estrogenic effects was estimated from the truly dissolved concentrations of EDCs in the Pearl River, which was lower than the estimated high risk according to the conventionally dissolved concentrations. It is suggested that the presence of colloids be incorporated into future water quality prediction and ecological risk assessment. Environ Toxicol Chem 2016;35:2474-2482.