Seasonal changes in pathways of dissolved organic carbon through a hillslope soil (Xeralf) with contrasting texture

Abstract

The pathways of dissolved organic carbon (DOC) through a podzolic soil (Xeralf) with strong texture contrast are described. During winter, most of the DOC passes through macropores in the profile and flows laterally through the B horizons. During summer the presence of dry, hydrophobic organic matter on the soil surface and the A1 horizon causes DOC to flow overland. DOC concentrations vary seasonally. Highest concentrations are measured during summer overland flow. For all horizons, the longer the dry period the greater the DOC concentration in the subsequent flow. During storm events there is a marked flushing effect in the B horizons but in the A horizon and the surface, DOC concentrations tend to rise. There was a marked decrease in DOC concentration in flow from the B3 compared to the upper horizons. This may be due to adsorption by fine clays lining the macropores.