Heterotrophic mineralization of amino acid nitrogen in subalpine Castle Lake, California

J. P. Zehr, R. P. Axler, C. R. Goldman

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10 Scopus citations


Heterotrophic mineralization of dissolved organic nitrogen (DON) can be a major source of N for primary producers. During the summer growing season in mesooligotrophic Castle Lake, dissolved inorganic nitrogen (DIN) is often below detection (<0.1 μg-atom N l-1) whereas DON can vary between 7 and 17 μg-atom N. The heterotrophic metabolism of glutamate resulted in the recycling of both carbon and nitrogen, but not at the same rate. The uptake of 15N- and 14C-labeled glutamate showed that C was preferentially assimilated relative to N resulting in an N-mineralization rate of 2.5-3.0 ng-atom N l-1 h-1. This suggests that heterotrophs in Castle Lake are not N-deficient, and metabolism of organic compounds results in the release of DIN which is available for primary production.

Original languageEnglish (US)
Pages (from-to)343-350
Number of pages8
JournalMarine Chemistry
Issue number4
StatePublished - Jul 1985

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