Soil water in the riparian zone as a source of carbon for a headwater stream

摘要: Conflicting views on the potential importance of soil water as a source dissolved organic carbon (DOC) in headwater streams are addressed by comparing chemistries waters riparian zone with an adjacent stream at upland site mid-Wales during one year. DOC, which whole is relatively refractory, was contrasted labile free amino acids (DFAAs). DOC distributions showed little temporal or spatial consistency, but concentrations almost always exceeded those (mean = 9.4 and 2.1 mg l−1, respectively). This represents average input some 2500 g C m−2 year−1 to stream, indicating quantitative DOC productivity. Total DFAA were <0.3% measured. Although their mean also higher (168.2 nmol l−1) than (113.9 l−1), this not consistent trend. Most probably DFAAs' lability resulted complete immobilization within streambed microporous discharge catchment runoff through streambed. Three major hydrological flow paths inferred correlating dynamics chemistry, well inorganic nitrogen (ammonium nitrate), between sampling points. A lack any dynamic relationship saturated through-flow bank suggested efficient streambed, prior its into stream; particularly significant baseflow. Correlations for both N unsaturated that, least flows, could directly influence stream. high degree correlation forest edge (6m from stream) that form macroporous transfer further back These results reveal complexity environment. It concluded can contribute substantial amounts ecosystem, must be key area chemical reactivity where much material initially processed. As delivery will depend hydrology zone, knowledge essential prerequisite modelling