title: Correlations of nonlinear sorption of organic solutes with soil/sediment physicochemical properties.
abstract: The estimation of solute sorptive behaviors is essential when direct sorption data are unavailable and will provide a convenient way to assess the fate and the biological activity of organic solutes in soil/sediment environments. In this study, the sorption of 2,4-dichlorophenol (2,4-DCP) on 19 soil/sediment samples and the sorption of 13 organic solutes on one sediment were investigated. All sorption isotherms are nonlinear and can be described satisfactorily by a simple dual-mode model (DMM): q(e)=KpCe+Q0 . bCe/(1+bCe), where Kp (mlg(-1)) is the partition coefficient; Ce (microgml(-1)) is the equilibrium concentration; Q0 (microgg(-1)) is the maximum adsorption capacity; Q0 . b (mlg(-1)) is the Langmuir-type isotherm slope in the low concentration (Henry's law) range and b (mlmicrog(-1)) is a constant related to the affinity of the surface for the solute. Based on these nonlinear sorption isotherms and similar other nonlinear isotherms, it is observed that, for both polar 2,4-DCP and nonpolar phenanthrene, Kp, Q0 and Q0 . b are linearly correlated with soil/sediment organic carbon content (f(oc) in the range of 0.118-53.7%). The results indicate that the nonlinear sorption of organic solutes results primarily from interactions with soil/sediment organic matter. The K*oc K*oc=Kp/f(oc)), Qoc (Qoc=Q0/f(oc)), Loc (Loc=Q0 . b/f(oc)) and b for a given organic solute with different soils/sediments are largely invariant. Furthermore, logK*oc, logb and logLoc for various organic solutes are correlated significantly with the solute logKow or logSw (logKow in the range of 0.9 to 5.13 and logSw in the range of -6.176 to -0.070). A fundamental empirical equation was then established to calculate approximately the nonlinear sorption from soil/sediment f(oc) and solute Sw for a given solute equilibrium concentration.
authors.affiliation: Department of Environmental Science, Xixi Campus, Zhejiang University, Hangzhou 310028, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Yang
authors.forename: Lizhong
authors.initials: L
authors.lastname: Zhu
authors.forename: Baofeng
authors.initials: B
authors.lastname: Lou
authors.forename: Baoliang
authors.initials: B
authors.lastname: Chen
mesh_terms: D000327:Adsorption; D000871:Anthelmintics / Q000737:chemistry*; D002733:Chlorophenols / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry; D008962:Models, Theoretical; D012989:Soil Pollutants / Q000032:analysis*; D013696:Temperature
chemical_list: D000871:Anthelmintics; D002733:Chlorophenols; D012989:Soil Pollutants; C004762:2,4-dichlorophenol