|Schmidt, BHM; Matzner, E: Abiotic reaction of nitrite with dissolved organic carbon? Testing the ferrous wheel hypothesis, Biogeochemistry, 93, 291-296 (2009)|
The Ferrous Wheel Hypothesis (Davidson et al. 2003) postulates the abiotic formation of dissolved organic N (DON) in forest floors, by the fast reaction of NO2 − with dissolved organic C (DOC). We investigated the abiotic reaction of NO2 − with dissolved organic matter extracted from six different forest floors under oxic conditions. Solutions differed in DOC concentrations (15–60 mg L−1), NO2 − concentrations (0, 2, 20 mg NO2 −-N L−1) and DOC/DON ratio (13.4–25.4). Concentrations of added NO2 − never decreased within 60 min, therefore, no DON formation from added NO2 − took place in any of the samples. Our results suggest that the reaction of NO2 − with natural DOC in forest floors is rather unlikely.