The influence of source on the sorption of dissolved organic carbon by soils

Abstract

We examined the influence of dissolved organic carbon (DOC) source on the sorption of DOC by two clayey and two sandy soils using seven extracts from plant tissues and organic soil horizons. Sorption characteristics, such as null-point DOC concentration, partition coefficient and intercept, were determined over the initial solution concentration range of 0-50 mg DOC L-1. The clayey soils had larger partition coefficients and higher null points than the sandy soils. There was an average three-fold variation in null-point DOC concentration and partition coefficient amongst the seven DOC extracts. Fractionation of the DOC samples into humic acid and hydrophobic and hydrophilic acids, bases and neutrals revealed weak relationships between the sorption characteristics and DOC chemistry.