This paper shows the continuous measurements of CO2 flux collected from a 10-m eddy covariance tower in a coastal-marine environment in the Canadian Arctic Archipelago over the course of a 17-month period. The extended length of data collection resulted in a unique dataset that includes measurements from two spring melt and summer seasons and one 20 autumn freeze-up. Generally, this paper is written well and conclusion is clear. However, for explanation of the pCO2 sw calculated based on the FCO2, K, and pCO2 air are unrealistic values (e.g. zero). Therefore, author should explain and adjust for the appropriate explanation. 

Comments are indicated in the following.  

Line 21: "air-sea" should "air–sea" (wider minus) throughout the text.

Line 21: Author indicated that sea ice is barrier. However, in lines 28–30, outgassing occurs during freezing sea ice. Author wanted to indicate zero after freezing. Therefore, to avoid misunderstanding, author should write correctly. 

Line 29: For positive flux values, it is nice if author will add "+" throughout the text.

Lines 32–33: "CO2 outgassing from the freezing period to be 5 to 15% of the magnitude of the estimated Arctic CO2 sink". If same direction of flux, we can say the percentage with respect to total. However, it is different direction (positive and negative). Can we say 5 to 15%? 

Line 55: CaCO3 salts. We do not need "salts".

Line 156: Author should add the detection limit, standard deviation, and accuracy of FCO2.

Line 176: CO2 in the brine? 

Line 197: Section of "Results and Discussion" will be divided into "Results" section and "Discussion" section.

Line 199: Freezing point of seawater?

Line 341: Sea ice melt water affects low pCO2 sw due to dilution effect in lead water etc. Author will indicate the potential effect of pCO2 dilution effect by the melt water supply based on salinity data. 

Line 370: It would be nice if author will compare with SST and pCO2 because pCO2 will change depend on temperature. Author can indicate that this pCO2 change can explain based on thermodynamic process or not. 

Line 399, "aqueous" does not need.

Line 400; For biological process, author should use reference (biological paper showing about this area) to show author's explanation in the text. 

Line 415: How about the high pCO2 water mixing with surface water? Because this area is polynya and high current. Can Duke et al. (2021) (pCO2 data) support author's conclusion? 

Lines 504–505: If minus 9.9 Tg-C, we can say that 3.5 to 10 percent of this total Arctic sink. However, 9.9 is positive. Therefore, can we say 3.5 to 10 percent of this total Arctic sink?

Line 572: Author can indicate Sims et al. (2023) in the pCO2 discussion which will help author's assumption of relationships between flux and pCO2.

Lines 581–582: Same comments as lines 504–505. 

Line 567: Only physical factors? 

Table 1: Flux means CO2 flux?

Table 1: It is unknown how to decide the date for seasonal transition. 

Table 2: "Note that in this instance only the use of terms spring, summer, and fall are defined based on the zero crossings of the local regression curve from Figure 3 (and therefore straddle the seasonal demarcations defined in Table 1).". I cannot understand this. Could author explain detail?

Figure 1: It is nice if author will show the island shape and position of tower in the island.

Figure 4: Author should add 10 and –10 for the vertical axis.

Figure 4: Why FCO2 deviated widely during late spring to early fall as compared to winter and late fall?

Figure 5: I cannot imagine that pCO2 become from 600 to zero within 9 hours. What is the mechanism driving such a big change? I expect that eq1 is not fit. How about the ice temperature change during 9 hours?

Figure 9: Author will check the relationship between SST and pCO2, also SSS to understand the direct relationships between pCO2 and environmental factors.