Organic nitrogen total

Figure 14.7 Vertical section of total organic nitrogen (TON) constructed using hitherto unpublished data collected hy D. Hansell along USJGOFS southern leg (Cruise TN043 of Thomas G. Thompson http //usjgofs.whoi.edu/jg/dir/jgofs/).

Mineralization is usually defined as the production of ammonium from soil organic matter. This is sometimes called ammonification, which is a less confusing term. Mineralization usually causes only a small fractionation ( l%o) between soil organic matter and soil ammonium. In general, the 6 N of soil ammonium is usually within a few per mil of the composition of total organic nitrogen in the soil. 

Because many ocean regions are nitrogen limited, once Nr is added, it is rapidly used by phytoplankton in the euphotic zone. Zooplankton graze on the phytoplankton. Nr can recycle within the euphotic zone or can be transferred to the subeuphotic zone as total organic nitrogen (TON) where most is mineralized to nitrate and some is deposited to the sediments. 

J.H. Lowry, K.H. Mancy, A rapid automated system for the analysis of dissolved total organic nitrogen in aqueous solutions, Water Res. 12 (1978) 471. 

Total Organic Nitrogen Content in Various Types of Wine (Grams per liter)... 

A Kjeldahl analyzer is used to determine ammonia (by a digestionless method), or total organic nitrogen by acid digestion followed by steam distillation and potentiometric titration. This unit performs all steps automatically and calculates the %N in the sample. The technique is suitable for liquids and powders that can be catalytically converted to ammonium ion. This method is complementary to the combustion method, which is much faster and has become the method of choice for analysis of nitrogen content. 

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