Impact of Sea Ice Melting on Summer Air-Sea CO2 Exchange in the East Siberian Sea

Ahra Mo,Tae-Wook Kim,Kitae Kim,Sung-Ho Kang,Eun Jin Yang,Young Ho Ko,Kitack Lee,Dongseon Kim

doi:10.3389/fmars.2022.766810

Abstract

The role of sea ice melting on the air-sea CO2 flux was investigated at two ice camps in the East Siberian Sea of the Arctic Ocean. On average, sea ice samples from the two ice camps had a total alkalinity (TA) of ∼108 and ∼31 μmol kg–1 and a corresponding salinity of 1.39 and 0.36, respectively. A portion (18–23% as an average) of these sea ice TA values was estimated to exist in the sea ice with zero salinity, which indicates the excess TA was likely attributed to chemical (CaCO3 formation and dissolution) and biological processes in the sea ice. The dilution by sea ice melting could increase the oceanic CO2 uptake to 11–12 mmol m–2 d–1 over the next 21 days if the mixed layer depth and sea ice thickness were assumed to be 18.5 and 1.5 m, respectively. This role can be further enhanced by adding TA (including excess TA) from sea ice melting, but a simultaneous release of dissolved inorganic carbon (DIC) counteracts the effect of TA supply. In our study region, the additional impact of sea ice melting with close to unity TA:DIC ratio on air-sea CO2 exchange was not significant.

Highlights

The carbon dioxide concentration in the atmosphere has increased from ∼280 ppm in the preindustrial era to the current ∼410 ppm due to human activities, such as the use of fossil fuels, cement production, and land-use changes (Le Quéré et al, 2018)
The overall values of these components were lower in IC2, with sea ice meltwater (SICE) in the range 0.05–1.23 and TAICE and DICICE in the ranges of 3–87 and 16–77 μmol kg−1, respectively
We evaluated variations in the total carbon content due to sea ice melting and estimated the corresponding enhancements of the air-to-sea CO2 flux in the East Siberian Sea

Summary

Introduction

The carbon dioxide concentration in the atmosphere has increased from ∼280 ppm in the preindustrial era to the current ∼410 ppm due to human activities, such as the use of fossil fuels, cement production, and land-use changes (Le Quéré et al, 2018). During this period of increasing atmospheric CO2, more than a third of anthropogenic CO2 has been absorbed by the ocean through the air-sea gas exchange (Sabine et al, 2004; Gruber et al, 2009, 2019).

Objectives

Methods

Results

Conclusion