Sources and Transformation of Dissolved Organic Carbon in the Harp Lake Forested Catchment: The Role of Soils

Abstract

The 14C content of dissolved organic carbon (DOC) in streams, soil water and groundwaters in the Harp Lake catchment in Ontario, Canada, reflect a mixture of DOC sources, including both contemporary plant material and 14C-depleted soil organic matter. The concentration and isotopic content of DOC in streams is highly variable, reflecting the complex flow path of the source water entering the streams. The characteristics of groundwater DOC are set in the soil column, either through DOC production in the deeper soil layers, or through preferential decomposition and/or sorption of 14C-enriched DOC components from percolating waters. We estimate the relative magnitudes of decomposition, transport and sorption as sinks for DOC produced in forested catchment soils.