Maximizing carbon sequestration on ultramafic mine tailings remediation through bioamendments and microbial inoculants

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Mining for metals results in a waste product known as tailings. These tailings are composed of fine grain residual material devoid of metal product and stored within engineered facilities, often hundreds of hectares in size, throughout Canada. Few plants can grow on tailings and they are costly to maintain in order to prevent damage to neighbouring ecosystems. Restoration of tailings offers a solution to restore vegetation and ecosystem functioning to areas that otherwise provide no ecological benefit. Importantly, as plants grow they remove carbon from the atmosphere and store it in their biomass and in the soil. This acts as a natural climate solution to reduce atmospheric carbon dioxide concentrations required to combat climate change. British Columbia, Quebec, and the Yukon contain large quantities of nickel rich bedrock, known as ultramafic rock. Mining creates large carbon emissions and it is important to offset these emissions to reduce the impact on the environment. Importantly, soil microbes are responsible for nutrient cycling and decomposition processes that are vital for healthy soils. But little is known about how to restore plant life and functioning microbial communities within or on ultramafic tailings. This project explores the use of organic waste products from the pulp & paper industry and microbial communities from natural systems to maximize natural vegetation growth on ultramafic tailings. This approach reduces the ecological footprint of organic waste producing industries, while restoring damaged ecosystems caused by industrial mining processes. The results of this research may provide multiple environmental benefits. Using an organic waste product combined with the nutrient cycling powers of natural soil microbes, tailings impacts may be mitigated through stabilization preventing erosion into adjacent ecosystems, restoring ecosystem services (e.g. wildlife habitat) and offsetting carbon emissions from the initial mining process. It will also enable other tailings sites across Canada to maximize carbon storage, helping to lower Canada's greenhouse gas emissions and contribute toward Canada's net-zero greenhouse gas emissions by 2050.