Seasonal Water Mass Evolution and Non‐Redfield Dynamics Enhance CO<sub>2</sub> Uptake in the Chukchi Sea

Ouyang, Zhangxian; Collins, Andrew; Li, Yun; Qi, Di; Arrigo, Kevin R.; Zhuang, Yanpei; Nishino, Shigeto; Humphreys, Matthew; Kosugi, Naohiro; Murata, Akihiko; Kirchman, David L.; Chen, Liqi; Chen, Jianfang; Cai, Wei‐Jun

doi:10.1029/2021jc018326

Cited by 9 publications

(4 citation statements)

References 90 publications

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“…For instance, community composition shifts to smaller cells with a lower N requirement (Mills et al 2018; Lee et al 2013). It has also been suggested in previous investigations of non‐Redfield stoichiometry that C overconsumption in the polar late summer could potentially be a plastic response to changes in N availability resulting in a more efficient C uptake or a decoupling between the C and N processes (Frigstad et al 2014; Ouyang 2022). However, most of this work does not consider that labile DON could be supporting increased C uptake processes (Sipler and Bronk 2015).…”

Section: Discussionmentioning

confidence: 87%

Late‐season nitrogen uptake across the western coastal Alaskan Arctic

Stanley

Sipler

Roberts

et al. 2023

Limnology & Oceanography

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Productivity in the Arctic is expected to increase as temperatures and the number of open water days rise. With this increased productivity, the coastal shelves of the Arctic Ocean may act as a sink for atmospheric carbon. However, this storage is dependent on a sufficient nitrogen (N) supply and current literature on biogeochemical rates of N uptake in this region is severely limited. Here, we report the spatial extent and rate at which the aquatic microbial community utilizes inorganic and organic N substrates in the Alaskan Arctic during late summer. Uptake rates (> 0.3 μm) were measured in 2016 and 2017 using isotopically labeled ammonium (), nitrate (), urea, and mixed algal amino acids. Rates of regeneration were also measured to investigate the contribution of remineralized N to primary production. Primary production was estimated using isotopically labeled bicarbonate. We found that N species uptake varied by location. Although was the form of N taken up at the greatest rate at most sites, we also found that uptake rates of urea could be greater than and that amino acid uptake was widespread. Supporting previous studies, uptake rates were correlated with primary production rates. Variability in nutrient reservoirs and sampling conditions in the Chukchi Sea between the 2 yr were responsible for some of the variances observed in estimated recycling rates and primary production. Understanding which N sources support this late‐season primary production requires obtaining uptake rates for a diverse range of inorganic and organic N substrates.

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Section: Discussionmentioning

confidence: 87%

Late‐season nitrogen uptake across the western coastal Alaskan Arctic

Stanley

Sipler

Roberts

et al. 2023

Limnology & Oceanography

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“…The CO 2 uptake in the southern Barents Sea and the coastal region in the East Siberian Sea, the Laptev Sea, and the Kara Sea is increasing in the p CO 2 products but decreasing (or increasing outgassing in some regions that are CO 2 sources) in the ocean biogeochemical hindcast and data assimilation models (Figures 10a and 10b), but both estimates have large uncertainties in these regions as mentioned in Section 4.2.2. Recently, an increasing trend of summertime CO 2 uptake in the Chukchi Sea has been reported (Ouyang et al., 2020, 2022; Tu et al., 2021). In this study, the large increasing CO 2 uptake trend in the Chukchi Sea is detected in the p CO 2 products but it is small in the models (Figures 14a and 14b).…”

Section: Discussionmentioning

confidence: 98%

An Assessment of CO₂ Uptake in the Arctic Ocean From 1985 to 2018

Yasunaka,

Manizza,

Terhaar

et al. 2023

Global Biogeochemical Cycles

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As a contribution to the Regional Carbon Cycle Assessment and Processes phase 2 (RECCAP2) project, we present synthesized estimates of Arctic Ocean sea‐air CO2 fluxes and their uncertainties from surface ocean pCO2‐observation products, ocean biogeochemical hindcast and data assimilation models, and atmospheric inversions. For the period of 1985–2018, the Arctic Ocean was a net sink of CO2 of 116 ± 4 TgC yr−1 in the pCO2 products, 92 ± 30 TgC yr−1 in the models, and 91 ± 21 TgC yr−1 in the atmospheric inversions. The CO2 uptake peaks in late summer and early autumn, and is low in winter when sea ice inhibits sea‐air fluxes. The long‐term mean CO2 uptake in the Arctic Ocean is primarily caused by steady‐state fluxes of natural carbon (70% ± 15%), and enhanced by the atmospheric CO2 increase (19% ± 5%) and climate change (11% ± 18%). The annual mean CO2 uptake increased from 1985 to 2018 at a rate of 31 ± 13 TgC yr−1 dec−1 in the pCO2 products, 10 ± 4 TgC yr−1 dec−1 in the models, and 32 ± 16 TgC yr−1 dec−1 in the atmospheric inversions. Moreover, 77% ± 38% of the trend in the net CO2 uptake over time is caused by climate change, primarily due to rapid sea ice loss in recent years. Furthermore, true uncertainties may be larger than the given ensemble standard deviations due to common structural biases across all individual estimates.

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“…The DO samples were immediately analyzed on board using the spectrophotometric method based on Winkler titration with a precision of AE 1 μmol kg À1 (Bryan et al 1976;Ouyang et al 2022b). Nutrient samples were measured using a Continuous Flow Analyzer (Skalar San ++ ) based on standard colorimetric methods (Grasshoff et al 1999;Zhuang et al 2022), and data were from Zhuang et al (2022).…”

Section: Cruise Descriptionmentioning

confidence: 99%

Sea‐ice loss accelerates carbon cycling and enhances seasonal extremes of acidification in the Arctic Chukchi Sea

Zhang,

Wu,

Cai

et al. 2024

Limnol Oceanogr Letters

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The Chukchi Sea shelf (CSS) is a highly productive region in the Arctic Ocean and it is highly efficient for absorbing atmospheric carbon dioxide and exporting and retaining carbon in the deep sea. However, with global warming, the carbon retention time in CSS may decrease, leading to less efficient carbon export. Here, we investigate the seasonal variability of carbonate chemistry in CSS using three sets of late‐ vs. early‐summer reoccupations of the same transect. Our findings demonstrate substantially increased and rapid degradation of biologically produced organic matter and therefore acidification over time in the southern CSS due to earlier sea‐ice retreat, resulting in significantly shorter carbon retention time. In sharp contrast, no increased degradation has been observed in the northern CSS where photosynthesis has just commenced. In the future, climate change would further diminish the carbon export capacity and exacerbate seasonal acidification not only within CSS but also across other polar coastal oceans.

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Seasonal Water Mass Evolution and Non‐Redfield Dynamics Enhance CO₂ Uptake in the Chukchi Sea

Abstract: As the first region of the Arctic Ocean to receive water and nutrient inputs from the Pacific Ocean, the Chukchi Sea is a unique ecosystem affecting Arctic biogeochemical cycles, food-web function, and air-sea CO 2 fluxes (

Cited by 9 publications

References 90 publications

Late‐season nitrogen uptake across the western coastal Alaskan Arctic

Late‐season nitrogen uptake across the western coastal Alaskan Arctic

An Assessment of CO₂ Uptake in the Arctic Ocean From 1985 to 2018

Sea‐ice loss accelerates carbon cycling and enhances seasonal extremes of acidification in the Arctic Chukchi Sea

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Seasonal Water Mass Evolution and Non‐Redfield Dynamics Enhance CO2 Uptake in the Chukchi Sea

Abstract: As the first region of the Arctic Ocean to receive water and nutrient inputs from the Pacific Ocean, the Chukchi Sea is a unique ecosystem affecting Arctic biogeochemical cycles, food-web function, and air-sea CO 2 fluxes (

Cited by 9 publications

References 90 publications

Late‐season nitrogen uptake across the western coastal Alaskan Arctic

Late‐season nitrogen uptake across the western coastal Alaskan Arctic

An Assessment of CO2 Uptake in the Arctic Ocean From 1985 to 2018

Sea‐ice loss accelerates carbon cycling and enhances seasonal extremes of acidification in the Arctic Chukchi Sea

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Seasonal Water Mass Evolution and Non‐Redfield Dynamics Enhance CO₂ Uptake in the Chukchi Sea

An Assessment of CO₂ Uptake in the Arctic Ocean From 1985 to 2018