Nitrogen Cycling in a Microcosm Simulation of the Northern Arm of the Great Salt Lake

Nitrogen cycling was studied in the hypersaline northern arm of the Great Salt Lake (332,480 mg/l total dissolved solids) using a sediment-water microcosm simulation of that system. The study demonstrated that nitrate, ammonia, and urea were not stimulating to the halophilic bacteria in the microcosm. The bacteria were simulated only indirectly simulated bacterial growth. In addition, no nitrification could be demonstrated during the study. Weekly analyses of water samples from the north arm of the lake itself showed that nitrate and nitrite were absent, leaving ammonia as the only significant form of inorganic nitrogen in the northern lake basin. Other work on lake samples has indicated that no nitrogen fixation occurs in this system. Thus, the absence of nitrogen fixation, nitrification, and denitrification (because of the absence of nitrate) make it apparent that the production and the utilization of ammonia are the only two significant nitrogen cycling pathways operating in this system. The equilibrium established between the conversion of ammonia into organic nitrogen and the production of ammonia from mineralization of this organic matter is then responsible for the conditions which are found in the northern arm of the Great Salt Lake