Occurrence and Degradation of Free and Conjugated Estrogens in a River Receiving Feedlot Animal Discharge

This study analyzed concentrations of 17β-estradiol (E2), estrone (E1), estriol (E3), 17α-ethynylestradiol (EE2), diethylstilbestrol (DES), 17β-estradiol-3-sulfate (E2-3S), estrone-3-sulfate (E1-3S), 17β-estradiol-3-glucuronide (E2-3G), and estrone-3-glucuronide (E1-3G) in river water, received from intensive feedlot operations wastewater in WuLo Creek, Taiwan. Moreover, the estrogen degradation in situ was analyzed. The average concentrations were 54.15 ± 31.42, 9.71 ± 6.42 and 3.55 ± 2.41 ng/L for E1, E2 and E3, respectively. The concentrations and order were similar to the polluted river and higher than most rivers’ concentrations. The conjugated estrogen concentrations ranged from ND to 13.2 ng/L (E1-3S), ND to 10.4 ng/L (E2-3S), ND to 10.0 ng/L (E1-3G), and ND to 3.6 ng/L (E2-3G), and the detection rates were 76%, 71%, 56%, and 15%, respectively. In the present study, the high detection rates of conjugate estrogen were more elevated than the water receiving STP effluent, suggesting that the source was the river water close to the animal wastewater discharge. In the degradation test, the DES concentrations slightly declined after 24 h, but E1-3G did not significantly change over time (p > 0.05). The degradation of free estrogen occurred during the first 12 h period, and residual concentration was not further decreased after 24 h. In the environment, E1 had higher concentrations than E2 and E3, suggesting that E1 was more resistant to degradation than E2 and E3 at low concentrations. However, the degradation test in the present study suggested that E1 rapidly degraded at high ambient concentrations due to the high degradation constant.