05 Jan 2023
05 Jan 2023
Status: this preprint is open for discussion.

Considerations for hypothetical carbon dioxide removal via alkalinity addition in the Amazon River watershed

Linquan Mu, Jaime B. Palter, and Hongjie Wang Linquan Mu et al.
  • Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, 02882, USA

Abstract. The Amazon River plume plays a critical role in shaping the carbonate chemistry over a vast area in the western tropical North Atlantic. We explore a thought experiment of ocean alkalinity enhancement (OAE) via hypothetical quicklime addition in the Amazon River watershed, examining the response of carbonate chemistry and air-sea carbon dioxide flux to the alkalinity addition. Through a series of sensitivity tests, we show that the detectability of the OAE-induced alkalinity increment depends on the perturbation strength (or size of the alkalinity addition, ΔTA) and the number of samples: there is a 90 % chance to meet a minimum detectability requirement with ΔTA > 15 μmol kg-1 and sample size > 40, given background variability of 15–30 μmol kg-1. OAE-induced pCO2 reduction at the Amazon plume surface would range between 0–25 μatm when ΔTA = 20 μmol kg-1, decreasing with increasing salinity. Adding 20 μmol kg-1 of alkalinity at the river mouth could elevate the total carbon uptake in the Amazon River plume by 0.07–0.1 MtCO2 month-1. Such thought experiments are useful in designing minimalistic field trials and setting achievable goals for monitoring, reporting, and verification purposes.

Linquan Mu et al.

Status: open (until 18 Feb 2023)

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  • RC1: 'Comment on egusphere-2022-1505', Anonymous Referee #1, 27 Jan 2023 reply

Linquan Mu et al.


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Short summary
Enhancing ocean alkalinity accelerates carbon dioxide removal from the atmosphere. We hypothetically added alkalinity to the Amazon River and examined the increment of the carbon uptake by the Amazon plume. We also investigated the minimum alkalinity addition in which this perturbation at the river mouth could be detected above the natural variability.