Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/4/2014
Publication Date: 1/1/2015
Publication URL: http://handle.nal.usda.gov/10113/60030
Citation: Bai, X., Casey, F.X., Hakk, H., Desutter, T.M., Oduor, P.G., Khan, E. 2015. Sorption and degradation of 17ß-estradiol-17-sulfate in sterilized soil-water systems. Chemosphere. 119:1322-1328. Interpretive Summary: Endocrine disrupting estrogens are commonly found in lake, river, and well waters. Farm animals and wildlife typically eliminate estrogens as non-toxic, water-soluble conjugates, not as the parent estrogen. Our research has investigated how and why the parent estrogens appear in surface and groundwaters when they are excreted mainly as conjugates. We previously demonstrated that estrogen conjugates dissolved in water were transported through soil, and a measurable amount was eventually converted back to parent (unconjugated) estrogens. For this study, we hypothesized that microbes and a healthy microbial environment were necessary before this conversion could occur in soil. Using soils devoid of microbial activity we demonstrated that active microbial populations were not an important factor in the conversion of estrogen-conjugates to parent estrogens. Instead, we learned that this transformation of estrogen conjugates in soil/water systems might involve soil minerals to promote this reaction. Our findings suggested that the transport of unconjugated estrogens derived from estrogen conjugates into ground or surface waters would occur to the same degree in most soil types regardless of the biological activity or organic matter content. Eliminating the introduction of estrogens into the environment from animal wastes would necessitate their destruction prior to manure field application.
Technical Abstract: To identify abiotic processes that govern the fate of a sulfate conjugated estrogen, 17ß-estradiol-17-sulfate (E2-17S), soil batch experiments were conducted to investigate the dissipation, sorption, and degradation of radiolabeled E2-17S under sterilized conditions. The aqueous dissipation half-lives (DT50) for E2-17S ranged from 2.5 to 9.3 h for the topsoil of high organic carbon (OC) content (1.29%), but E2-17S remained at _80% of applied dose in the low OC (0.26%) subsoil by 14 d. The non-linear sorption isotherms indicated limited sorption of E2-17S, and the concentration-dependent log KOC values were 2.20 and 2.45 for the topsoil and subsoil, respectively. Additionally, two types of hydroxyl E2-17S (OH-E2-17S and diOH-E2-17S) were found as major metabolites in the aqueous phase, which represented 9–25% and 6–7% of applied dose for the topsoil and subsoil at 14 d, respectively. Free estrogens, 17ß-estradiol (E2) and estrone (E1), were detected from the sorbed phase of the soil–water systems.