title: Sorption and desorption of selected non-steroidal anti-inflammatory drugs in an agricultural loam-textured soil.
abstract: Non-steroidal, anti-inflammatory drugs (NSAIDs) are widely used pharmaceutical products with analgesic and anti-inflammatory effects that are consistently detected in municipal wastewater systems and in municipal biosolids. Land application of biosolids and irrigation with reclaimed wastewater introduces these compounds into agricultural environments, which is an emerging issue of concern for ecosystem health. In this study, the sorption-desorption behaviour of four commonly consumed NSAIDs, including naproxen (NPX), ibuprofen (IBU), ketoprofen (KTF), and diclofenac (DCF), was examined in a loam textured soil exposed to either an individual-compound or a mixture of the four NSAIDs. The proportion of NSAIDs adsorbed to the soil in the mixture-compound system was 72%, 55%, 50% and 45%, for diclofenac, naproxen, ketoprofen, and ibuprofen, respectively, and differed slightly from the individual compound adsorption. Diclofenac displayed strong sorption and low desorption in both the individual-compound and mixture-compound systems. Naproxen and ibuprofen exhibited significant differences between the adsorption isotherms of the individual-compound and mixture-compound systems. Results of this study highlight differences in the sorption behaviour of NSAIDs, when present as mixtures, possibly through multilayer bonding effects or complexation with cationic metals or organo-clays from the soil. Soil organic matter (SOM) may have played a role in determining some of the interactions between the compounds but other factors associated with the mixture-compound system, such as cation bridging or multilayer cooperative adsorption. Desorption data suggests that the mechanisms involved in binding NSAIDs to the soil surface are also influence by the presence of other compounds in a mixture. A reduction in desorption was observed for all four NSAIDs in the mixture-compound system relative to the individual-compound system, but were greatest for naproxen and ibuprofen. The sorption-desorption hysteresis increased for naproxen and ibuprofen in the mixture-compound system. This study suggests that cooperative adsorption plays a role in the interaction of NSAIDs when present as mixtures rather than as individual compounds.
authors.affiliation: Department of Engineering, Faculty of Agriculture, Dalhousie University, Truro, Nova Scotia, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Engineering, Faculty of Agriculture, Dalhousie University, Truro, Nova Scotia, Canada. Electronic address: gprice@dal.ca.
authors.forename: G W
authors.initials: GW
authors.lastname: Price
authors.affiliation: Department of Civil and Resource Engineering, Faculty of Engineering, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Jamieson
authors.affiliation: Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, Nova Scotia, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Burton
authors.affiliation: Centre for Built Environment, Faculty of Applied Science and Engineering Technology, Seneca College, Toronto, Ontario, Canada.
authors.forename: K
authors.initials: K
authors.lastname: Khosravi
mesh_terms: D000327:Adsorption; D000383:Agriculture; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry*; D004008:Diclofenac / Q000737:chemistry*; D007052:Ibuprofen / Q000737:chemistry*; D007660:Ketoprofen / Q000737:chemistry*; D009288:Naproxen / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry*
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D012987:Soil; D012989:Soil Pollutants; D004008:Diclofenac; D009288:Naproxen; D007660:Ketoprofen; D007052:Ibuprofen
keywords: Agricultural soil; Emerging substances of concern; Kd; Non-steroidal anti-inflammatory drug (NSAIDs); Pharmaceuticals; Sorption-desorption hysteresis