Passive Sequestration of Atmospheric CO₂ through Coupled Plant-Mineral Reactions in Urban soils

Abstract

Photosynthetic removal of CO(2) from the atmosphere is an important planetary carbon dioxide removal mechanism. Naturally, an amount equivalent to all atmospheric carbon passes through the coupled plant-soil system within 7 years. Plants cycle up to 40% of photosynthesized carbon through their roots, providing a flux of C at depth into the soil system. Root-exuded carboxylic acids have the potential to supply 4-5 micromoles C hr(-1)g(-1) fresh weight to the soil solution, and enhance silicate mineral weathering. Ultimately, the final product of these root-driven processes is CO(2), present in solution as bicarbonate. This combines with Ca liberated by corrosion associated with silicate mineral weathering to enter the soil-water system and to produce pedogenic calcium carbonate precipitates. Combining understanding of photosynthesis and plant root physiology with knowledge of mineral weathering provides an opportunity to design artificial soils or to plan land use in ways that maximize removal and sequestration of atmospheric CO(2) through artificially enhanced pedogenic carbonate precipitation. This process requires relatively low energy and infrastructure inputs. It offers a sustainable carbon dioxide removal mechanism analogous to the use of constructed wetlands for the passive remediation of contaminated waters, and is likely to achieve wide public acceptance.

The dissolution of olivine added to soil: Implications for enhanced weathering

“…Intermittent rainfall, and/or evapotranspiration, may result in soil pore water becoming saturated or oversaturated with minerals. Soil pH may fluctuate as a function of rapidly evolving carbon dioxide partial pressure (see Manning and Renforth (2012) for summary) or organic compound degradation and exudation (particularly low molecular mass organic acids; van Hees et al, 2000). Imprinted over these natural processes may be additional weathering from human activity (e.g.…”

Geotechnical Requirements for Capturing Co2 Through Highways Land

“…The choice of planting and management of vegetation on roadside verges and central reserves could also influence calcite formation. Carbon stored in carbonates is plant derived, implying that encouraging plant growth on engineered urban soils may facilitate carbon capture [8], as well as providing other ecosystem services associated with vegetated land. Although roads generally have a negative impact on biodiversity (for example [23], [24]), sympathetically managed or restored roadside verges make an important contribution to the conservation of grassland species (for example [25]) and pollinating insects [26].…”

“…that commonly occur in basic igneous rocks (for example basalts and dolerites), or from artificial calcium silicate and hydroxide minerals within concrete and cement [8], [9]. Carbonate carbon is mainly derived ultimately from photosynthesis, based on stable isotope studies [10].…”

Saprolitologia aplicada à gênese e às implicações ambientais de regolitos do Estado de Pernambuco

“…A captura de CO2 atmosférico por reações geoquímicas existentes no manto do intemperismo é historicamente relatada como um dos principais processos atenuantes do efeito estufa (MARINI, 2007;ALLEN et al, 2009;MANNING;RENFORTH, 2013). A captura de CO2 atmosférico e a formação de carbonatos é geralmente descrita em regolitos provenientes de basalto (MCGRAIL et al, 2006;GOLDBERG, 2007;SLAGLE, 2008).…”

“…A atividade metabólica, principalmente o processo de respiração, da fauna e da flora associada ao regolito também devem contribuir para o aporte de CO2 para a solução circundante BERNER, 1998;MANNING, 2008;MANNING;RENFORTH, 2013).…”