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Factors controlling the partitioning of pyrene to dissolved organic matter extracted from different soils
Author(s) -
Marschner B.,
Winkler R.,
JÖdemann D.
Publication year - 2005
Publication title -
european journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 1351-0754
DOI - 10.1111/j.1365-2389.2004.00678.x
Subject(s) - chemistry , pyrene , dissolved organic carbon , environmental chemistry , soil water , partition coefficient , humus , absorbance , humic acid , organic matter , chromatography , organic chemistry , soil science , fertilizer , environmental science
Summary The mobility of hydrophobic organic compounds (HOCs) in soils can be influenced by the presence of dissolved organic matter (DOM). While numerous studies have determined interactions of HOCs with humic and fulvic acids, only few data exist on the partitioning of HOCs to natural, non‐fractionated DOM as it occurs in soil solutions. In this study, DOM was extracted from 17 soil samples with a broad range of chemical and physical properties, originating from different land uses. The partition coefficients of pyrene to DOM were determined in all soil extracts and for two commercial humic acids using the fluorescence quenching method. For the soil extracts, log K DOC values ranged from 3.2 to 4.5 litres kg −1 . For the Aldrich and Fluka humic acids, log K DOC was 4.98 and 4.96 litres kg −1 , respectively, thus indicating that they are not representative for soil DOM. After excluding these two values, the statistical analysis of the data showed a significant negative correlation between log K DOC and pH. This was also shown for one sample where the pH was adjusted to values ranging from 3 to 9. A multiple regression analysis suggested that ultraviolet absorbance at 280 nm (an indicator for aromaticity) and the E4:E6 ratio (an indicator for molecular weight) had additional effects on log K DOC . The results indicate that the partitioning of pyrene to DOM is reduced at alkaline pH, probably due to the increased polarity of the organic macromolecules resulting from the deprotonation of functional groups. Only within a narrow pH range was the K DOC of pyrene mainly related to the aromaticity of DOM.