Dynamics of the Nitrogen Cycle in Lakes.

摘要

The importance of nitrogen fixation by blue-green algal populations was established,and nitrogen-15was introduced for measuring in situ nitrogen fixation rates in natural waters. Nitrogen-15techniques were developed for measuring nitrate and ammonia uptake,and the importanc3of ammonia as a nitrogen source in lakes became apparent. Denitrification rates were measured accurately in anoxic lake waters. Rapid ammonia supply and turnover was demonstrated in lake waters. This implies that substantial nitrogen regeneration takes place constantly in surface waters of these lakes,and that this can provide a major nutrient source for the photosynthetic population. Such ammonia supply is independent of any sediment interaction. The limnological information available for interior Alaska has been expanded through the work. The Dumas method using a Coleman nitrogen analyzer were introduced for preparing nitrogen samples for mass spectrometry. (Author)