Water soluble organic carbon and its measurement in soil and sediment

The term water soluble organic carbon (WSOC) was defined as the entire pool of water soluble organic carbon either sorbed on soil or sediment particles or dissolved in interstitial pore water. The potential of soil and sediment for providing DOC to natural waters depends on the content and the sorption coefficient of the WSOC. A procedure of multiple solid–water ratios was proposed for simultaneous determination of the content and the sorption coefficient of the WSOC. The method was applied to several soil and sediment samples collected from the Yichun River Basin, China. The content and the sorption coefficient of the WSOC in a wetland soil and the A horizon of an upland soil were found to be higher than those in the AB horizon of the upland soil and a river bottom sediment. Both parameters correlate positively with the humic substances content of the samples.