Design and Construction of an Experimental Setup to Enhance Mineral Weathering through the Activity of Soil Organisms

Enhanced weathering is a carbon dioxide removal technology that involves the reaction of silicate rock with carbon dioxide and water. Microbes and other soil biota can stimulate this weathering reaction, but their potential impact on enhanced weathering is yet unknown. Here, we aim to unravel the impact of various soil biota on enhanced weathering.

One of the soil biota we're interested in is earthworm. Earthworms play a fundamental role in soil. They can increase weathering by respiration, ingestion of soil, production of mucus, or stimulation of microbial activity.

Here, we're interested in testing if earthworms can enhance weathering in an artificial system primarily made of minerals. Accurately quantifying weathering rates and associated carbon dioxide capture is the biggest experimental challenge. Different indicators show different weathering rates and do not always scale with carbon dioxide capture.

In this experimental setup, we can measure multiple indicators. Our aim of the protocol is to understand the impacts of earthworms, bacteria, and fungi on weathering rates, while also studying the abiotic factors boosting it. However, the ultimate aim of the protocol is to find the optimal combination of biotic and abiotic factors to maximize carbon dioxide removal.

The main benefits relate to scale and level of control, and we are now able to test a much larger number of combinations of soil biota and minerals, all under the same experimental conditions, and that allows us to pick up synergies, interactions that we would never have picked up in more conventional, smaller experimental designs. Our results will showcase the potential of soil biota to draw CO2 from the atmosphere, and if we can prove that, that would be a huge step in finding ways to help mitigate global warming.