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Title: Contribution of urea-N to nitrification in the Southern Ocean west of the Antarctic Peninsula
NOTE: THIS MS IS TO BE SUBMITTED FOLLOWING OUTCOME OF NATURE COMMUNICATIONS REVIEW OF A COMPANION MS. ABSTRACT (246 words, 1,457 characters including spaces) We measured the oxidation rates of N supplied as urea (UO) and ammonium (AO) in continental shelf and slope waters of the Southern Ocean west of the Antarctic Peninsula during the austral summer of 2018. The response of rates to substrate concentration varied by water mass. Rates increased moderately (up to 200%) with 440 vs 6 nM substrate amendments to samples from the Winter Water (WW, sampled at 35-100 m), but decreased (down to 7%) in samples from the Circumpolar Deep Water (CDW, 175-1000 m). AO rates decreased more than UO rates. This response suggests that CDW Thaumarchaeota are not well adapted to short-term variation in substrate concentrations and that even low amendments (we used 44 or 47 nM) may inhibit oxidation. Rates of AO and UO were not correlated; nor were they correlated with the abundance, or ratios of abundance, of marker genes; or with [NH4+]; or [urea]. UO and AO were distributed uniformly across the study area within a water mass; however, they displayed strong vertical gradients. Rates in most samples from Antarctic Surface Water (ASW, 10-15 m) were below the limit of detection. Highest rates of both processes were in samples from the WW (21.2 and 1.6 nmol L-1 d-1 for AO vs UO, respectively) and CDW (7.9 and 2.5 nmol L-1 d-1), comparable to rates from the study area reported previously. The contribution of UO to nitrite production was ~24% of that from AO alone, comparable to ratios measured at lower latitudes.  more » « less
Award ID(s):
1643466
PAR ID:
10468106
Author(s) / Creator(s):
; ; ; ; ; ;
Publisher / Repository:
ASM: Applied and Environmental Microbiology
Date Published:
Journal Name:
Applied and environmental microbiology
ISSN:
1070-6291
Subject(s) / Keyword(s):
Thaumarchaeota nitrification ammonia-oxidation urea ureC amoA Nitrospina Antarctica PAL-LTER Southern-Ocean
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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