Sorption of Organic Pollutants to Thatch as Influenced by Thatch Chemical Properties.

Attempts to validate pesticide transport models for use in turf have demonstrated that model performance is highly sensitive to the pesticide sorption value assigned to thatch. Past thatch sorption research indicate that current pesticide sorption data bases, which are largely derived from mineral soil sorption investigations, do not accurately reflect the pesticide sorption capacity of turfgass thatch. We examined the sorption capacity of two non-ionic pesticide metabolites to 11 thatch samples, and measured the carbon (C), Nitrogen (N), hydrogen (H) and oxygen (O) content of each sample to determine if atomic ratios of the three elements could be used to predict the sorption capacity of thatch. The sorption of naphthalene and 1-napthol was independent of the O/C and (O+N)/C atomic ratios of thatch as well as to C content of thatch. Naphthalene linear (Kd) and non linear (K’f) sorption coefficients were positively correlated with thatch N/C and H/C atomic ratio’s of thatch, with the two ratio’s explaining 48% to 51%  of variation in Kd, and 36 to 40% of the variation in K’f.  The sorption of 1-napthol to thatch was not significantly correlated with thatch N/C or H/C atomic ratio. Our results suggest that the state of organic matter decomposition within thatch, as measured by the N/C or H/C atomic ratio, is a better predictor of the sorption of hydrophobic organic compounds to thatch than is the overall amount of organic carbon present in thatch.