Modeling degradation and metabolite formation kinetics of estrone-3-sulfate in agricultural soils.
Estrone-3-sulfate (E1-3S), formed in the kidneys of pregnant cattle, can act as a precursor to the free hormone estrone (E1) known for its endocrine disrupting potential in wildlife. Laboratory microcosm studies were conducted to investigate the aerobic degradation of E1-3S in three contrasting pasture soils at 7.5, 15, and 25 degrees C. Deconjugation of E1-3S resulted in the formation of the metabolite E1. Two kinetic models-a single first-order and a biexponential kinetic model-were applied to fit the observed degradation dynamics and to derive degradation end-points (DT50 and DT90) for the parent compound and the metabolite for each condition. Model selection and evaluation of their performance were based on a suit of statistical measures (one-way ANOVA, AIC(c), R2(adj), chi2 error-%, and SRMSE). The results showed rapid initial degradation of E1-3S, followed by a much slower decline with time, and rate of degradation was temperature dependent. The DT50 and DT90 values of E1-3S ranged from a few hours to several days, while the formation of the major metabolite (E1) was concomitant with E1-3S degradation in all nonsterile soils. The parent compound degradation and formation and subsequent dissipation of metabolite were successfully predicted by both models, however, the nonlinear biexponential model improved the goodness-of-fit parameters in most cases.
Scherr
Frank F
FF
Landcare Research New Zealand Limited, Private Bag 3127, Hamilton, New Zealand.
Sarmah
Ajit K
AK
Di
Hong J
HJ
Cameron
Keith C
KC
D000383:Agriculture; D000818:Animals; D001673:Biodegradation, Environmental; D002417:Cattle; D004970:Estrone / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D005260:Female; D011247:Pregnancy; D012987:Soil; D012989:Soil Pollutants / Q000378:metabolism*
D012987:Soil; D012989:Soil Pollutants; D004970:Estrone; C017296:estrone sulfate