Sorption of Nonionic Organic Compounds by Kentucky Bluegrass Leaves and Thatch

Abstract Soil organic matter and plant litter layers are largely responsible for the immobility of organic compounds in agronomic environments. The objective of this research was to determine the sorption of nonionic organic compounds by turfgrass leaves and thatch and to correlate the sorption data with water solubilities ( S w ) and octanol/water partition coefficients ( K ow ). Batch suspension experiments for phenanthrene, fenarimol (α‐(2‐chlorophenyl)‐α‐(4‐chlorophenyl)‐5‐pyrimidinemethanol), 1,2,4‐trichlorobenzene, ethoprop ( o ‐ethyl s,s ‐dipropyl phosphorodithioate), and acetanilide (acetylaminobenzene) with S w from 1 to 5405 mg L −1 were completed on Kentucky bluegrass ( Poa pratensis L. cv. Touchdown) leaves and thatch. The resulting linear sorption isotherms ( r 2 > 0.922) for these organic compounds are consistent with a partitioning mechanism between water and leaves or thatch. The partition coefficients ( K ) for thatch ranged from 6.32 for acetanilide to 793 for phenanthrene. The K coefficients for leaves ranged from 3.53 for acetanilide to 2520 for phenanthrene. Sorption coefficients normalized for organic C content of the sorbent ( K oc ) were smaller for leaves and thatch than K oc values for soil organic C. The sorption coefficients for Kentucky bluegrass leaves had linear relationships with both the S w and K ow of the organic compounds. The K values for Kentucky bluegrass leaves could be predicted from S w and K ow , but values for thatch were highly variable. Both leaves and thatch were strong sorbents for organic compounds and should be expected to have a significant impact on the sorption and fate of chemicals applied to turf.