Impacts of dissolved phosphorus and soil-mineral-fluid interactions on CO2 removal through enhanced weathering of wollastonite in soils

The weathering of silicate minerals removes carbon dioxide (CO2) from the atmosphere over geologic timescales and is also investigated as an engineered strategy to mitigate climate change on decadal timescales. “Enhanced rock weathering” (ERW) a removal that involves spreading pulverized, highly reactive at Earth's surface such within agricultural natural soils. rate efficacy ERW in soils remove CO2 difficult quantify owing complex geochemical environment including biological-mineral-fluid-atmosphere interactions human interventions occur. Column experiments containing wollastonite [CaSiO3] were conducted investigate processes during ERW, determine potential impact P-bearing fertilizers removal. Columns wollastonite, soil, or 8:1 soil-wollastonite mixtures irrigated with de-ionized water 1 × 10?4 M K3PO4 solution. Analysis column effluent concentrations indicated P was rapidly removed solution retained columns, little difference between columns those receiving Bulk rates significantly enhanced presence compared alone. Cation strongly impacted by adsorption soil surfaces, complicating efforts estimate capture. Based estimated Si release, maximum 255 kg t?1 amendment yr?1 captured mixture columns. majority stored soil-bearing most likely soil-generated rather than directly atmosphere. results this study indicate may limit ability enhance weathering, behaviour differs substantially pure mineral phases, budgets must be carefully constrained assess source CO2. Moreover, leachate cations HCO3? not serve accurate indicators extent least short term, due numerous control their soils, sorption components.