River Liming

Oceans & marine

River Ölfusá just North of Selfoss, South Iceland

The pH of water is lowered when it takes up atmospheric carbon. Given that the Earth’s oceans serve as a major carbon sink, there is increasing interest in the possibility to artificially increase the alkalinity of water to restore pH to previous levels, and/or increase carbon uptake potential.

Like Ocean Alkalinity Enhancement, river liming seeks to increase alkalinity of water sources to increase atmospheric CO2 uptake. Because the limed rivers would ultimately flow into the ocean, this measure could thereby also be used as an extended introduction mechanism for Ocean Alkalinity Enhancement.

Technological Readiness Level (TRL)

Low 1

Apart from scarce earlier mentionings (Köhler et al 2010), the idea of liming rivers, or even wastewater (Cai and Jiao, 2022), by olivine has seemingly only very recently been forwarded in several presentations (Rønninget al, 2023; Sterling et al, 2023) and a thought experiment (Mu et al, 2023). Because these suggestions have been done in the form of presentations, and no peer reviewed articles have seemingly been published on the idea, details and results of the announced experiments are left out here.

Technological Readiness Level (TRL)

A technology with a TRL of 1-3: TRL 1 – Basic; TRL 2 – Concept formulated; TRL 3 – Experimental proof of concept

Scalability

Unknown 0

Timeliness for near-future effects

Unknown 0

Northern + Arctic potential

Unknown 0

Arctic rivers are important for the alkalinity of the Arctic ocean and its CO2 uptake (Olafsson et al, 2021), and river liming could therefore perhaps be a suitable measure if alkalinity enhancement is found to be a feasible CDR technique.

Global potential

Unknown 0

Cost - benefit

Unknown 0

Environmental risks

Unknown 0

Köhler et al (2010) states that the distribution of material and the broader environmental effects of liming should be especially thoroughly explored for rivers and coastal ecosystems.

Community impacts

Unknown 0

Ease of reversibility

Unknown 0

Risk of termination shock

Unknown 0

Legality/governance

High 3

Legality/governance

Currently legal to deploy, with governance structures in place to facilitate it and/or financial incentives to develop it

Scientific/media attention

Low 1

As mentioned above, the idea has likely mainly been suggested in a few recent presentations at the 2023 EGU meeting in Vienna.

Scientific/media attention

Very low attention from individuals and/or abandoned ideas; low media attention; no commercial interest.

References

Cai, W. J., & Jiao, N. (2022). Wastewater alkalinity addition as a novel approach for ocean negative carbon emissions. The Innovation, 3(4), 100272. https://doi.org/10.1016/j.xinn.2022.10027

Köhler, P., Hartmann, J., & Wolf-Gladrow, D. A. (2010). Geoengineering potential of artificially enhanced silicate weathering of olivine. Proceedings of the National Academy of Sciences, 107(47), 20228-20233. https://doi.org/10.1073/pnas.1000545107

Mu, L., Palter, J. B., and Wang, H. (2023). Considerations for hypothetical carbon dioxide removal via alkalinity addition in the Amazon River watershed, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2022-1505

Olafsson, J., Olafsdottir, S. R., Takahashi, T., Danielsen, M., & Arnarson, T. S. (2021). Enhancement of the North Atlantic CO 2 sink by Arctic Waters. Biogeosciences, 18(5), 1689-1701. https://doi.org/10.5194/bg-18-1689-2021

Rønning , J., Campbell, J. S., Renforth, P., & Löscher, C. (2023). Enhanced Weathering of Olivine in Rivers for Carbon Dioxide Removal (No. EGU23-11269). Copernicus Meetings. https://doi.org/10.5194/egusphere-egu23-11269

Sterling, S., Halfyard, E., and Hart, K. (2023) Addition of Alkalinity to Rivers: a novel strategy for Ocean Alkalinity Enhancement, EGU General Assembly 2023, Vienna, Austria, 24–28 Apr 2023, EGU23-16677, https://doi.org/10.5194/egusphere-egu23-16677

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