Typical Endocrine Disrupting Compounds in Rivers of Northeast China: Occurrence, Partitioning, and Risk Assessment.

Liao River Basin (LRB), located in northeast China, is one of seven largest river basins in China. The Daliao River Watershed (DLRW) is severely disturbed by human activities in the LRB. In this study, three rivers within the DLRW-Xi River (XR), Hun River (HR), and Daliao River (DLR)-were selected as sampling locations. The distribution, partitioning, and risk assessment of four endocrine-disrupting compounds (EDCs), e.g., bisphenol A (BPA), 17β-estradiol (E2), estrone (E1), and 17α-ethinyl estradiol (EE2), in the rivers were investigated. The results showed that the concentration of BPA was generally higher than those of the other three steroidal estrogens in the sampling locations. The estrogen levels in the XR were greater than those in the HR and DLR. As a result of a decreasing river flow rate during the frozen season and irregular wastewater discharge from human domestic activities and manufacture processing, the total concentration of selected EDCs in the frozen season was much greater than those in nonfrozen season with the highest concentration in surface water of the XR at 1131.0 ng/L for BPA, 1235.0 ng/L for E1, 1253.5 ng/L for E2, and 17,111.5 ng/L for EE2, respectively. Based on the field-measured BPA concentrations in the sediment and water, the organic carbon-normalized partition coefficient (K ) of BPA were calculated with the values of 2884-45,031 L/kg; the concentration of BPA in sediment was positive correlated with the content of OC (R  = 0.932). The risk assessment made by estradiol equivalent (EEQ) and risk quotient (RQ) showed that 64.7% of sampling sites were exposed to high estrogenic activity (∑EEQ > 1) and high risk in surface water, whereas the RQ values of all selected estrogens in sediment were in medium or minimal risk. Both EE2 and E1 were the major contributors to the total estrogenic activity and risk quotient in surface water.