Retention and Transport of Pharmaceuticals and Personal Care Products in Soils As Affected By Soil Organic Matter and Microaggregates.

This study addresses the effects of soil organic matter (SOM) and microaggregates on the retention and transport of three representative pharmaceuticals and personal care products (PPCPs) (ibuprofen, carbamazepine, and bisphenol A) in an agricultural soil. A series of sorption-desorption batch tests and breakthrough column experiments were conducted using manure-treated and non-manured soils. Results show that SOM could substantially influence their environmental behaviors via surface-coating and pore-filling. Surface-coating decreases the sorption of dissociated PPCPs (e.g., ibuprofen) but increases the sorption of non-dissociated PPCPs (e.g., carbamazepine and bisphenol A), while pore-filling enhances the retention of all them by providing nano/micropores and limiting diffusion. The higher retention and less mobility of PPCPs in soil microaggregates than in bulk soils suggest that SOM and altered soil pore structure could exert a coupled effect on PPCP retention. Difference in the elution of PPCPs with low surface tension solution (i.e., 20% ethanol) in the presence and absence of SOM indicates that PPCPs prefer to retain in SOM-filled pores. Overall, ibuprofen has high environmental risk, whereas carbamazepine and bisphenol A could be readily retarded in agricultural soils. This study implies that SOM accrual has a large potential for reducing the off-site risks of PPCPs.