Severe nitrogen gas (N2) depletion in lakes may have implications for N2fixation and for model structures describing the nitrogen (N) cycle. To determine whether this is likely to occur, we first reviewed the general processes influencing the N2cycle in lakes. Second, we empirically analysed N2concentrations in various stations and depths of Lake Erken, Sweden during the beginning and the end of the summer stratification period of 2004. Overall, no significant deviations from N2saturation from any stations or depths were observed during the study period. Third, we developed a simple, one-box gas model to investigate possible effects on lake water from processes described in the literature that affect the N2concentration. Simulations indicated that bottom waters and other isolated water bodies may show strong deviations from N2saturation during certain conditions differing from those during summers in Lake Erken. Simulated surface waters were always N2saturated in all types of lakes where the water column was in direct contact with the air. We quantified all probable fluxes, showed that the N2concentration in surface waters vastly exceeds the half-saturation constant for N uptake by phytoplankton, and concluded that it is unlikely that N2fixation is ever limited by the N2concentration. Modellers of lake eutrophication may regard N2as being available in excess. © 2006 Elsevier B.V. All rights reserved.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below