@article {KNZ001315, title = {Saturation of NO3- uptake in prairie streams as a function of acute and chronic N exposure}, journal = {Journal of the North American Benthological Society}, volume = {29}, year = {2010}, pages = {627 -635}, abstract = {

We conducted a series of stepwise NO3\− additions to investigate the response of NO3\− uptake to short-term (acute) changes in N concentration in 3 prairie streams. Observed NO3\− uptake rates increased with short-term elevations in NO3\− concentration and were consistent with linear and Michaelis\–Menten kinetics models. We compiled these data with uptake rates from additional published studies to calculate robust estimates of N uptake kinetics for prairie streams. Half-saturation coefficients based on compiled data were 6.7 \µg/L for NH4+ and 67 \µg/L for NO3\−-N. This difference in half-saturation coefficients suggests that NH4+ is more efficiently assimilated than NO3\−, indicating a preference for NH4+ as an N source. Similarly, ambient concentrations of NH4+ and NO3\− were less than their respective half-saturation coefficients, and aerial uptake rates were generally \<5\% of the maximum, suggesting severe limitation of N uptake at ambient conditions. The observed pattern of uptake kinetics suggests that physiological constraints limit biotic N uptake in these low-N streams and contrasts with the pattern of uptake observed in streams with chronically elevated ambient NO3\− concentrations.

}, keywords = {LTER-KNZ, Biogeochemistry, Kings Creek, Konza Prairie, nitrate uptake}, doi = {10.1899/09-021.1}, url = {https://www.journals.uchicago.edu/doi/10.1899/09-021.1}, author = {O{\textquoteright}Brien, J.M. and W. K. Dodds} }