Mitigation Of Ocean Acidification Through Enhanced Olvine Weathering

Chair: Jessica Ericson

Francesc Montserrat1,3, Phil Renforth2, Martine Leermakers3, Jens Hartmann4 and Filip Meysman1,3

1 Royal Netherland Institute for Sea Research (NIOZ), 4401NT, Yerseke, The Netherlands

2 Cardiff University, School of Earth and Ocean Sciences, Cardiff, CF10 3AT, United Kingdom

3 Free University of Brussels, Pleinlaan 2, 1050, Brussels, Belgium

4 University of Hamburg, Bundesstraße 55, 20146, Hamburg, Germany

 

Background:

To mitigate the effects of ocean acidification and enhance oceanic CO2 uptake, a climate intervention or -engineering approach has been proposed as a pro-active conservation strategy. Enhanced Weathering of Olivine targets the enhancement of the natural process of silicate weathering in order to locally manage ocean chemistry. The core concept consists of rapidly weathering silicate mineral olivine, distributed in water bodies, on beaches and along coasts. However, the idea is highly conceptual and both mechanistic understanding of the involved processes and empirical evidence are lacking.

Methods:

In a series of mesocosm experiments, the proxies, processes and effects of olivine weathering in seawater have been investigated. Sand-grade olivine has been experimentally subjected to model conditions of coastal marine environments (water movement, differing seawater composition, macrofaunal bioturbation). During these experiments, the dissolution reaction products in the overlying water were measured  and the solid mineral phase later analysed.

Findings:

The experiments have shown that olivine dissolution increases the alkalinity in seawater, and hence locally alleviate or even counteract acidification effects. Various processes like seawater composition, metabolic dissolution and bioturbation strongly affect the dissolution rate of olivine in coastal settings.

Conclusions:

Olivine dissolution in seawater can be best measured by monitoring the release of Nickel. Marine olivine dissolution increases the alkalinity and hence the uptake of atmospheric CO2, but this process is constrained by Magnesium present in seawater. Bioturbation activity strongly enhances olivine dissolution in both experimental and natural sediments. As such, Enhanced Weathering of Olivine appears a useful mitigation tool against Ocean Acidification.