Dissolved Organic Carbon Concentrations In Different Soils

Dissolved organic carbon (DOC) concentrations in the topsoil of seven UK sites, were monitored on a fortnightly basis for a one year period. The results showed a clear difference in concentration and flux with soil type ranging from a mean annual average DOC concentration of 35 g m-3 (flux of 19 g C m-2 yr-1 in a peat soil to 2 g m-3 (flux of 3.5 g C m-2 yr-1 in an acid ranker. Combining values with data from published literature allows a wide range of soil and vegetation types to be compared and indicates that coniferous forest sites release higher DOC concentrations than grassland sites in temperate regions with approximate ranges of 37 60 g m-3 and 2 23 g m-3 respectively. These findings are currently being explored further by looking at the relationships between the DOC flux and a range of soil parameters at each site simultaneously. The aim is to identify variables, that influence the DOC concentration and flux, and to find common links between sites, which may account for the DOC variation. Estimated soil carbon turnover times using 14C isotopic data at each UK site are being determined. These are to be combined with published data and the relationship between carbon turnover and DOC flux in the topsoil will be analysed. Preliminary results from published data point towards an existing relationship for some soils types, although this requires further investigation.