Sorption of hydrophobic organic pollutants on soils and sediments

 

Authors: Toul J, Bezděk J, Kovářová M, Boháček Z, Hanák J, Milička J, Müller P

Published in: Bulletin of Geosciences, volume 78, issue 3; pages: 205 - 223; Accepted in revised form 5 May 2003;

Keywords: soil, sediment, chemical analyses, organic matter, hydrophobic organic pollutants, alkanes, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorinated pesticides, data quality, correlations, environmental interpretations,

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Abstract

Sorption interactions between selected hydrophobic organic pollutants as sorbates and various natural sorbents in two-phase systems sorbent - water were experimentally tested by means of both batch (static) and column elution (dynamic) methods. Relatively persistent priority pollutants such as polycyclic aromatic hydrocarbons (naphthalene, anthracene and fluoranthene), organochlorinated pesticides (methoxychlor, hexachlorobenzene and lindane) and triazine herbicides (simazine and atrazine) were used as model hydrophobic sorbates. The collection of the examined natural sorbents included lake sediments, soils, reference samples of subsoil sedimentary rocks and some technical products as synthetic reference materials. By using batch methods, the distribution/sorption coefficients KD and/or parameters KF and 1/n of the Freundlich isotherm equation for the respective sorption systems were determined. In the case of natural sorbents with significant contents of organic matter, the corresponding normalised distribution/sorption coefficients KOC or KOC(F) were calculated and compared with known reference values of these parameters. On the basis of some observed differences between experimental and expected data, the role of organic matter and some other factors affecting the sorption processes, limitations of the simple model of hydrophobic sorption and reliability of sorption data are discussed.
Elution sequences and phase distribution balances of the pollutants, determined by elutions of the sorbates with water from sorbent columns, also reflected differences in their sorption parameters in detail. In comparison with batch methods, however, the column methods are less effective and for numerous reasons unsuitable for the measurement of sorption parameters.