Sorption of estrogens, triclosan, and caffeine in a sandy loam and a silt loam soil

Abstract

Recently, pharmaceuticals and personal care products (PPCPs) have been identified in the environment. Concerns on the occurrence and fate of these compounds in soil and sediment have significantly increased. It is believed that these PPCPs sorb to soil and sediment; however, information on sorption of PPCPs is still limited. In this study, the sorption of estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), triclosan, and caffeine to two loam soils and Ottawa sand was assessed. Sorption was determined using the batch equilibrium method. Freundlich and linear equations were applied to the sorption data in order to obtain sorption isotherms for each test compound and the respective sorption coefficients (K f, K d, and log K oc). The results indicated that isotherms were generally linear over the range of concentrations tested. Sorption capacity was directly related to organic carbon content such that partition coefficients for silt loam soil > sandy loam soil > sand. Triclosan had the highest values of Kf (231 in the sandy loam and 344 in the silt loam) and K d (256 in the sandy loam and 282 in the silt loam). The log Koc values for the PPCPs tested varied from 1.85 to 4.30. Desorption tests over 24 h indicated that caffeine had the greatest desorption capacity (>15%) among the compounds in sandy loam soil, while triclosan had the lowest desorption capacity ( sandy loam soil > sand.