title: Analysis of organic contaminant desorption kinetic data for sediments and soils: implications for the Tenax extraction time for the determination of bioavailable concentrations.
abstract: Solid-phase extractions with adsorbents like Tenax have been widely used to assess bioaccessible or bioavailable concentrations and non-extractable residues (NER) of organic contaminants in soils or sediments. This paper presents an analysis of literature rate constants and fractions for rapid, slow and very slow contaminant desorption from soils and sediments. Contaminant fractions desorbed from sediment to Tenax in 6 or 24h were evaluated as to their adequacy as a proxy for rapidly desorbing fractions, which have been shown to correlate with bioavailable concentrations. Desorption rate constants appear to decrease with increasing contaminant n-octanol-water partition coefficient. The ratio of the fraction of contaminant desorbed from sediment to Tenax in 6h and the rapidly desorbing fraction appeared to slightly decrease on increasing contaminant hydrophobicity. This was not the case for the extraction for 24h. Rapidly desorbing fractions or bioavailable fractions can be estimated, within a factor of 1.4, by multiplying the fraction desorbed in 24h by a factor of 0.7.
authors.affiliation: Aquatic Ecology and Water Quality Management Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Deltares, P.O. Box 85467, 3508 AL Utrecht, The Netherlands.
authors.forename: Paul C M
authors.initials: PC
authors.lastname: van Noort
authors.affiliation: Aquatic Ecology and Water Quality Management Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; Board for Authorisation of Plant Protection Products & Biocides (Ctgb), P.O. Box 217, 6700 AE Wageningen, The Netherlands.
authors.forename: Anton
authors.initials: A
authors.lastname: Poot
authors.affiliation: Aquatic Ecology and Water Quality Management Group, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands; IMARES-Institute for Marine Resources and Ecosystem Studies, Wageningen UR, Haringkade 1, 1976 CP IJmuiden, The Netherlands. Electronic address: bart.koelmans@wur.nl.
authors.forename: Albert A
authors.initials: AA
authors.lastname: Koelmans
mesh_terms: D065966:Absorption, Physicochemical; D052918:Environmental Restoration and Remediation; D019015:Geologic Sediments / Q000737:chemistry*; D007700:Kinetics; D011108:Polymers / Q000032:analysis / Q000737:chemistry*; D012987:Soil / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D011108:Polymers; D012987:Soil; D014874:Water Pollutants, Chemical; C010514:tenax
keywords: Bioavailability; Desorption; Non-extractable residue; Rate constants; Tenax