Phytoplankton Response to Increased Nickel in the Context of Ocean Alkalinity Enhancement

[Geoengineering News]

https://bg.copernicus.org/preprints/bg-2023-130/

Authors

Xiaoke Xin, Giulia Faucher, and Ulf Riebesell

How to cite. Xin, X., Faucher, G., and Riebesell, U.: Phytoplankton Response to Increased Nickel in the Context of Ocean Alkalinity Enhancement, Biogeosciences Discuss. [preprint], https://doi.org/10.5194/bg-2023-130, in review, 2023.

Received: 07 Aug 2023 – Discussion started: 21 Aug 2023

Abstract. Ocean alkalinity enhancement (OAE) is considered one of the most promising approaches to actively remove carbon dioxide (CO2) from the atmosphere by accelerating the natural process of rock weathering. This approach involves introducing alkaline substances sourced from natural mineral deposits such as olivine, basalt, and carbonates or obtained from industrial waste products such as steel slags, into seawater and dispersing them over coastal areas. Some of these natural and industrial substances contain trace metals, which would be released into the oceans along with the alkalinity enhancement. The trace metals could serve as micronutrients for marine organisms at low concentrations, but could potentially become toxic at high concentrations, adversely affecting marine biota. To comprehensively assess the feasibility of OAE, it is crucial to understand how the phytoplankton, which forms the base of marine food webs, responds to ocean alkalinization and associated trace metal perturbations. In this study, we investigated the toxicity of nickel on three representative phytoplankton species across a range of Ni concentrations (from 0 to 100 µmol L-1 with 12 µmol L-1 synthetic organic ligand). The results showed that the growth of the tested species was impacted differently. The low growth inhibition and high IC50 (concentration to inhibit growth rate by 50 %) revealed that both the coccolithophore Emiliania huxleyi and the dinoflagellate Amphidinium carterae were mildly impacted by the increase in Ni concentrations while the rapid response to exposure of Ni, high growth rate inhibition, and low IC50 of Thalassiosira weissflogii indicate low tolerance to Ni in this species. In conclusion, the variability in phytoplankton sensitivity to Ni suggests that for OAE applications with Ni-rich materials caution is required and critical toxic thresholds for Ni must be avoided.

Source: European Geosciences Union

[Michael Hayes]

Thanks to these authors, it is now believable that smelter slag likely should not be used for OAE. I would have never believed such nonsense would ever be seriously considered before reading this paper, as slag is loaded with a wide spectrum of toxins¹. 

I'll speculate that a coastal smelter operation likely has connections to a local mariculture operation which is having water pH problems and wants to claim a C credit for using the slag as a CDR. If so, my hat is off to the authors for their study, it is limited yet just how much work has to go into cautioning against biological insanity.

1) https://www.sciencedirect.com/science/article/abs/pii/S0957582021000483#:~:text=on%20eco%2Dsystem.-,Chromium%20(Cr)%2C%20lead%20(Pb)%2C%20mercury%20(,(CH)%2C%202013).

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