Biomineralization in plants as a long-term carbon sink

Abstract

Carbon sequestration in the global carbon cycle is almost always attributed to organic carbon storage alone, while soil mineral carbon is generally neglected. However, due to the longer residence time of mineral carbon in soils (10 2 -10 6 years), if stored in large quantities it represents a potentially more efficient sink. The aim of this study is to estimate the mineral carbon accumulation due to the tropical iroko tree (Milicia excelsa) in Ivory Coast. The iroko tree has the ability to accumulate mineral carbon as calcium carbonate (CaCO 3 ) in ferralitic soils, where CaCO 3 is not expected to precipitate. An estimate of this accumulation was made by titrating carbonate from two characteristic soil profiles in the iroko environment and by identifying calcium (Ca) sources. The system is considered as a net carbon sink because carbonate accumulation involves only atmospheric CO 2 and Ca from Ca-carbonate-free sources. Around one ton of mineral carbon was found in and around an 80-year-old iroko stump, proving the existence of a mineral carbon sink related to the iroko ecosystem. Conservation of iroko trees and the many other biomineralizing plant species is crucial to the maintenance of this mineral carbon sink.

Biocontrolled soil nutrient distribution under the influence of an oxalogenic-oxalotrophic ecosystem

“…Ca Tot and Mg Tot concentrations close to the tree were expected to be due to carbonate accumulations below and near the trees as in previous studies (e.g. Cailleau et al 2004Cailleau et al , 2011. Despite the rather low pH observed at this study site, as well as the absence of significant carbonate accumulation near the trunk, Ca Tot and Mg Tot gradients are present.…”

Use of the frc gene as a molecular marker to characterize oxalate-oxidizing bacterial abundance and diversity structure in soil

“…Oxalotrophic bacteria from soils close to such trees play an important role in carbon cycling, leading to a net accumulation of calcium carbonate that may constitute a long term mineral carbon sink via the oxalate-carbonate pathway (Braissant et al, 2002;Cailleau et al, 2004;Verrecchia et al, 2006). PCR amplifications using the set of primers frc171-F/frc627-R gave a single band at the expected size of 473 pb for the soil samples collected below the trees as well as for the reference soil (data not shown).…”

Mineral CO2 sequestration by environmental biotechnological processes

“…Lackner et al 1995 introduced a number of chemical and physical methods to increase the rate of the process by accelerating the weathering rate of silicate minerals and precipitation rate of carbonate minerals (Lackner et al, 1995). Application of biological processes has also shown to be a cost-effective approach for accelerating CO 2 sequestration by mineral carbonation (Bennett et al, 2001;Cailleau et al, 2004;Castanier et al, 1999;Huijgen et al, 2003;Mirjafari et al, 2007;Pokrovsky et al, 2009). Four biotechnological processes of: anaerobic digestion (AD), nitrogen removal, desulfurization and bioelectrochemical systems characterized by a sequence of an acid-and an alkalinity-producing steps were specified to be able to adopt the mineral CO 2 sequestration process (Salek et al, 2013b).…”