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Title: Chemoautotrophic production In continental shelf waters off the West Antarctic Peninsula
We performed assays of chemoautotrophic carbon fixation and compared measured rates to rates predicted from oxidation of ammonia (AO), urea (UO) and nitrite (NO) N. Water samples used in this study were taken from aerobic shelf waters at stations on the continental shelf and slope west of the Antarctic Peninsula during January and February of 2018 (LMG1801). Chemoautotrophic carbon fixation rates averaged 1.8 and 1.7 nmol C L-1 d-1 in Winter Water (WW, 35-100 m) and Circumpolar Deep Water (CDW, 175-1000 m) water masses, respectively. Integrated over 1 year and a 440 m water column (excluding the Antarctic Surface Water mass, 0-34 m), chemoautotrophic production accounted for ~7 gC m2 yr-1, compared to an estimated mean annual photoautotrophic production of 180 gC m2 y-1. Chemoautotrophy in WW samples supported by AO, UO or NO was the equivalent of 0.91, 0.06, 0.13 nmol C L-1 d-1, while it was the equivalent of 0.37, 0.21 and 0.08 nmol C L-1 d-1 in samples from the CDW water mass. Chemoautotrophy coupled to AO+UO accounted for ~124% and ~55% of measured C fixation rates in these water masses, while chemoautotrophy coupled to complete nitrification (AO+UO+NO) accounted for ~128 and ~60% of measured C fixation rates. The mean turnover times for nitrite pools base on NO were 138 ± 35 d and 15 ± 3 d in WW and CDW samples, respectively. The rate of nitrite production from AO+UO in WW and CDW samples was 503 ± 233 and 24 ± 7 nmol L-1 d-1, respectively. The replacement time for the nitrite pool in the WW water mass by AO+UO calculated from these averages is 33 d while it is 9 d in the CDW. These calculations suggest the possibility of an additional sink for nitrite in the WW.  more » « less
Award ID(s):
1643466
PAR ID:
10468100
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
XIII SCAR Biology Symposium https://www.scar.org/events/biology-symposia/
Date Published:
Subject(s) / Keyword(s):
ammonia-oxidation nitrite-oxidation nitrification chemoautotrophy Thaumarchaeota AOA new-production PAL-LTER Southern-Ocean
Format(s):
Medium: X
Location:
Christchurch New Zealand, 31 July 2023 to 4 August 2023
Sponsoring Org:
National Science Foundation
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