Potential Drought Mitigation Through Microbial Induced Calcite Precipitation‐MICP

Abstract

Extreme drought events occur more frequently due to climate change. Soil water loss through evaporation is therefore significantly intensified. This study introduces an environment‐friendly and sustainable bio‐mediated technique, known as microbially induced calcite precipitation (MICP), for water evaporation suppression in clayey soils. Through lab‐scale evaporation tests, we investigate the effects of cementation solution concentration (0.5, 1.0, and 1.5 mol/L) and MICP treatment procedure (one‐phase and two‐phase MICP methods) on both macroscale (e.g., water loss, desiccation cracking) and microscale (e.g., microstructure variations) behaviors of soils. Experimental results show that MICP is capable of improving water retention capacity and enhancing the inter‐particle bonding of clayey soils. Both water evaporation rate and total water loss decrease with the increasing concentration of cementation solution and the number of MICP treatment cycle. For most testing samples, both one‐phase and two‐phase MICP treatment methods have a similar influence on soil properties. Further microstructure characterizations reveal four key factors contributing to the improved soil response under drying, including dense surface crust, remediated desiccation cracks, smaller pore size and residual solutes. Dense structure of surface crust suppresses the migration of water vapor into the atmosphere. Calcite crystals tend to reduce the evaporation surface if precipitated within cracks, and clog the movement of pore water if precipitated within the soil pore space. This study is expected to improve the fundamental understanding of soil‐atmosphere interactions under MICP treatment and provide insights into the potential application of bio‐mediated technologies as a nature‐based solution for drought mitigation in arid and semi‐arid region.

Enhancing Soil Resilience to Climatic Wetting‐Drying Cycles Through a Bio‐Mediated Approach

“…This crust exhibits a stable porous structure (see Figure 12m) and functions as a protective layer on the soil surface. In arid climates, the CaCO 3 crust reduces water vapor diffusion from the soil to the atmosphere, thus decreasing the soil water evaporation rate and suppressing cracking (Liu, Tang, et al., 2021). The surface crust can mitigate soil erosion in regions with severe rainfall by protecting the underlying soil from runoff and reducing rainwater infiltration, thus preventing internal soil erosion.…”

“…MICP has also shown feasibility in erosion control and dust suppression (Liu, Xie, et al., 2021; Meyer et al., 2011; Salifu et al., 2016). Furthermore, recent studies have shown the benefits of MICP in enhancing soil resistance to desiccation cracking (Liu et al., 2020) and mitigating the adverse impacts of drought on soils by suppressing the soil water evaporation (Liu, Tang, et al., 2021).…”

Negative Pore Water Pressure in Aquitard Enhances Land Subsidence: Field, Laboratory, and Numerical Evidence

“…It contains 2% sand, 76% silt, 22% clay, and has a liquid limit of 37% and a plastic limit of 20%. Previous study indicates that the dominant clay minerals are illite and illite‐smectite (Liu et al., 2021). And the detailed physical characteristics of the soil can be found in previous literatures (e.g., Liu, Pollard, et al., 2013; Liu, Shi, et al., 2013)…”

“…It contains 2% sand, 76% silt, 22% clay, and has a liquid limit of 37% and a plastic limit of 20%. Previous study indicates that the dominant clay minerals are illite and illite-smectite (Liu et al, 2021). And the detailed physical characteristics of the soil can be found in previous literatures (e.g., Liu, Pollard, et al, 2013; Water table tubes are installed on the inner side of the model box every 10 cm, from 5 to 55 cm, in order to investigate the variation of water level and water pressure.…”

A simple method to determine the reactivity of calcium carbonate in soils

“…Calcium carbonate affects many soil physical and chemical properties. These include aggregation of primary particles, soil water retention, pH, micronutrient availability, stabilization of soil organic C, and NH 3 volatilization (Bronick & Lal, 2005; Liu et al., 2021; Loeppert & Suarez, 1996; Rowley et al., 2018; Ryan et al., 1981). However, these effects depend less on the total concentration of soil carbonate and more on the reactivity of that carbonate which is controlled by particle size and surface area (Estefan et al., 2013).…”