Association of endocrine-disrupting chemicals with total organic carbon in riverine water and suspended particulate matter from the Pearl River, China.

The distribution of endocrine-disrupting chemicals (EDCs) and its relationship with dissolved and particulate organic carbon (DOC and POC) was investigated in selected rivers of the Pearl River Delta, South China. The aqueous concentrations (average; ng/L) and particulate concentrations (average; ng/g, dry wt) for 4-tert-octylphenol (OP), 4-nonylphenol (NP), bisphenol A (BPA), and estrone (E1) were in the ranges of not detectable to 153 (31.8), 276 to 2,457 (1,178), 8.4 to 628 (161), and less than 1.5 to 11.5 (3.2), respectively, and 4.4 to 402 (98.1), 342 to 12,053 (4,922), 12.3 to 758 (128), and not detectable to 14.4, respectively. The highly significant correlation of EDCs with DOC and POC, and the similar regression slopes, implied the critical importance of DOC and POC on the distribution, transport, and fate of EDCs in the aquatic environment. The in situ particle-water partition coefficients (log K(OC)) for OP (4.89 ± 0.41), NP (5.05 ± 0.33), and BPA (4.34 ± 0.50) were close to those reported by other field studies, but one to two orders of magnitude higher than those predicted with n-octanol-water partition coefficient (K(OW)). The higher K(OC) values were attributed to the combined effects of low EDC concentrations, nonlinear sorption, and heterogeneity of POC and DOC. Moreover, a regression between in-situ K(OC) and K(OW) for phenolic xenoestrogens was observed (log K(OC) = 0.625 × log K(OW) + 2.28, r(2) = 0.99), suggesting that hydrophobicity contributed predominantly to the overall sorption of OP, NP, and BPA.