Many areas in the US are experiencing an increased frequency of large storm events including watersheds found in Ohio (Midwestern US). By simultaneously examining watershed fluxes of carbon (C), nitrogen (N), and phosphorus (P) in their numerous fractions (e.g. dissolved vs. particulate, organic vs. inorganic) over multiple years, it is possible to contrast how precipitation affects these forms as well as to quantify stoichiometric export ratios (C:N:P). C, N, and P exports were quantified using a high-frequency sampling regime for two water years in two Ohio watersheds of contrasting land use (agricultural vs forested). Focus was placed on how C, N, and P exports by form vary between the two watersheds with an emphasis on the importance of hydrology (e.g. baseflow, storm events). We also examined the temporal synchrony of carbon and nutrient exports between these two watersheds located 300 km apart as well as the C:N:P stoichiometry of the watershed fluxes.
Results/Conclusions
Results show that an increased frequency of large storm events differentially affects carbon, nitrogen, phosphorus flux and the different forms within an element. For example, particulate N, P, and C forms in the both watersheds were strongly impacted by extreme events with increased export during storms while the export of other forms, like dissolved inorganic carbon, were not strongly influenced by large storms. C:N:P ratios of exported materials were often greatly different between the two watersheds. DIN:SRP and DON:DOP export ratios were higher in the agricultural watershed than the forested, while DOC:DON and DOC:DOP were elevated in the forested watershed. Despite strong differences in watershed land use, we found significant temporal synchrony between the exports from the two watersheds. This suggests that climate may be a stronger driver of temporal C, N, and P exports than watershed land use, while land use may be more important in regulating the magnitude of exports.