The Sorption And Degradation Of Steroid Hormones In Typical Soils

The endocrine systems and reproductive systems of living beings can be badly disturbed by natural steroid hormones at low concentrations(ng/L), thus it was attractted extensive attentions worldwide. So far, the study about steroid hormones most focused on estrogens, whlile less on androgens and progesterones which studied less but detected frequently. This paper firstly explored the sorption and degradation of androstenedione and progesterone in typical soils. The effect of water contents, temperature, cattle manure dissovled organic matter (DOM) on the two environmental behavior were investigated, especially simulated the effect of repeated freeze-thaw cycles on degradation.(1)Batch equilibrium experiments were conducted to quantify the kinetic sorption and sorption equipment of androstenedione and progesterone to three different kinds of soils. Meanwhile, the effects of cattle manure dissovled organic matter (DOM) on sorption was also discussed. The results showed that sorption of androstenedione and progesterone involved two phases, including a fast sorption phase earlier and a slow sorption phase later. The characteristics of the sorption turned out to be well fit Freundlich isotherm equation with R2greater than0.83,0.89, respectively. The sorption of androstenedione and progesterone to three soils expressed nonlinear. The most isotherm deviation of androstenedione from linearity occurred in alluvial soil (n=0.37); while the sorption of progesterone in alluvial soil was close to linear (n=0.90). The Kf values of androstenedione and progesterone were6.0-20.2mg1-nLn/kg and25.2-107.8mg1-nLn/kg, and was correlated to the organic carbon content of soil (P<0.05). The sorption capacity of progesterone was stronger compared with that of androstenedione. The sorption capacity of the two hormones in soils behavored as black soils> alluvial soil> red soils. The sorption of androstenedione was enhanced significantly in three soils with lower co-existed DOM, while progesterone only in alluvial soil. The effect on the sorption displayed differently when the concentration of DOM got bigger. It is assumed that the organic carbon content of soil was the main composition that adsorbed steroid hormones. Nevertheless, the concentration of co-existed DOM seems like much higher actually, thus androstenedione and progesterone would be more likely to migrate to the surface water and groundwater.The degradation characteristics of and progesterone in three kinds of soils was studied through batch experiments indoor and effects of moisture content and temperature on degration were explored. The results showed that the degration of androstenedione and progesterone met the first-order kinetics equation very well. The value of R2were0.81-0.99and0.82-0.98. The degradation rate of two hormones were0.063-0.229d-1and0.033-0.215d-1when the moisture content was25%. The degradation rate of androstenedione and progesterone is the higher in alluvial soil and black soil than in red soil. The behavior of degradation was fast initially and slow later, just like characteristics of sorption. Compared with the non-sterilized soil, half-life of androstenedione and progesterone was prolonged in sterilized soil, which showed that effect of micro-biological degradation was dominated. Also, the increase of moisture content or temperature contributed to the degradation of androstenedione and progesterone in soil. While, degradation was inhibited in black soil coexisting cattle manure DOM. Besides, due to numerous microorganism was killed among the repeated freeze-thaw cycles, the degradation was inhibited.