Effect of temperature on rates of ammonium uptake and nitrification in the western coastal Arctic during winter, spring, and summer. Issue 12 (23rd December 2014)

• Record Type: Journal Article
• Authors: Baer, Steven E.; Connelly, Tara L.; Sipler, Rachel E.; Yager, Patricia L.; Bronk, Deborah A.
• Is Part Of: Global biogeochemical cycles. Volume 28:Issue 12(2014:Dec.)
• Page Start: 1455
• Page End: 1466
• Publication Date: 2014-12-23
• Subjects: Biogeochemical cycles -- Periodicals; Electronic journals; 577.1405
• DOI: 10.1002/2013GB004765
• Languages: English
• ISSNs: 0886-6236

Abstract

<abstract abstract-type="main"> <title>Abstract</title> <p>Biogeochemical rate processes in the Arctic are not currently well constrained, and there is very limited information on how rates may change as the region warms. Here we present data on the sensitivity of ammonium (NH₄⁺) uptake and nitrification rates to short‐term warming. Samples were collected from the Chukchi Sea off the coast of Barrow, Alaska, during winter, spring, and summer and incubated for 24 h in the dark with additions of ¹⁵NH₄⁺ at −1.5, 6, 13, and 20°C. Rates of NH₄⁺ uptake and nitrification were measured in conjunction with bacterial production. In all seasons, NH₄⁺ uptake rates were highest at temperatures similar to current summertime conditions but dropped off with increased warming, indicative of psychrophilic (i.e., cold‐loving) microbial communities. In contrast, nitrification rates were less sensitive to temperature and were higher in winter and spring compared to summer. These findings suggest that as the Arctic coastal ecosystem continues to warm, NH₄⁺ assimilation may become increasingly important, relative to nitrification, although the magnitude of NH₄⁺ assimilation would be still be lower than nitrification.</p> </abstract>