Sorption and transport of trenbolone and altrenogest photoproducts in soil–water systems†
This study evaluated the sorption and transport potential of seven phototransformation products of 17α-trenbolone, 17β-trenbolone, trendione, and altrenogest, along with the parent trienone steroids in batch and column soil–water systems. In batch systems, the target solutes exhibited linear isotherms, with values for sorption coefficients (log Koc) of parent steroids (2.46–2.76) higher than those for photoproducts (1.92–2.57). In column systems, the estimated retardation factors (Rsol) for parents (2.7–5.1) were ∼2–5 times higher than those for photoproducts (0.84–1.7). The log Koc (R2 = 0.75) and Rsol (R2 = 0.89–0.98) were well correlated with measured log Kow values, indicating that hydrophobic partitioning governed the soil–solute interaction of these biologically potent compounds in soil–water systems. These data indicated that photoproducts exhibited reduced sorption affinity and increased transport potential relative to more hydrophobic parent structures. In agroecosystems, traditional runoff management practices would be expected to exhibit reduced treatment effectiveness for photoproducts relative to the parent compounds of commonly used trienone steroids.