ISSN:
1365-2389
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
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 KDOC values ranged from 3.2 to 4.5 litres kg−1. For the Aldrich and Fluka humic acids, log KDOC 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 KDOC 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 KDOC. 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 KDOC of pyrene mainly related to the aromaticity of DOM.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2389.2004.00678.x
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