Soils and Beyond: Optimizing Sustainability Opportunities for Biochar

Biochar is most commonly considered for its use as a soil amendment, where it has gained attention for its potential to improve agricultural production and soil health. Twenty years of near exponential growth in investigation has demonstrated that biochar does not consistently deliver these benefits, due to variables in biochar, soil, climate, and cropping systems. While biochar can provide agronomic improvements in marginal soils, it is less likely to do so in temperate climates and fertile soils. Here, biochar and its coproducts may be better utilized for contaminant remediation or the substitution of nonrenewable or mining-intensive materials. The carbon sequestration function of biochar, via conversion of biomass to stable forms of carbon, does not depend on its incorporation into soil. To aid in the sustainable production and use of biochar, we offer two conceptual decision trees, and ask: What do we currently know about biochar? What are the critical gaps in knowledge? How should the scientific community move forward? Thoughtful answers to these questions can push biochar research towards more critical, mechanistic investigations, and guide the public in the smart, efficient use of biochar which extracts maximized benefits for variable uses, and optimizes its potential to enhance agricultural and environmental sustainability.

State-of-the-Art Review of the Applicability and Challenges of Microbial-Induced Calcite Precipitation (MICP) and Enzyme-Induced Calcite Precipitation (EICP) Techniques for Geotechnical and Geoenvironmental Applications

The development of alternatives to soil stabilization through mechanical and chemical stabilization has paved the way for the development of biostabilization methods. Since its development, researchers have used different bacteria species for soil treatment. Soil treatment through bioremediation techniques has been used to understand its effect on strength parameters and contaminant remediation. Using a living organism for binding the soil grains to make the soil mass dense and durable is the basic idea of soil biotreatment. Bacteria and enzymes are commonly utilized in biostabilization, which is a common method to encourage ureolysis, leading to calcite precipitation in the soil mass. Microbial-induced calcite precipitation (MICP) and enzyme-induced calcite precipitation (EICP) techniques are emerging trends in soil stabilization. Unlike conventional methods, these techniques are environmentally friendly and sustainable. This review determines the challenges, applicability, advantages, and disadvantages of MICP and EICP in soil treatment and their role in the improvement of the geotechnical and geoenvironmental properties of soil. It further elaborates on their probable mechanism in improving the soil properties in the natural and lab environments. Moreover, it looks into the effectiveness of biostabilization as a remediation of soil contamination. This review intends to present a hands-on adoptable treatment method for in situ implementation depending on specific site conditions.

Nanocellulose: a bioadsorbent for chemical contaminant remediation

The adsorption and desorption of contaminants by nanocellulose.

Soil science at the University of Alberta: a century of service to science and society

This paper highlights major activities and achievements in soil science by professors at the University of Alberta (U of A), which provide incredible benefits to society, provincially, nationally, and globally. Evolution of the soils profession in Alberta commenced in 1919 with the hiring of F.A. Wyatt, who developed the Department of Soil Science (DSS) and initiated a soil survey program in Alberta. J.D. Newton joined the department in 1922, teaching and supporting soil surveys that led to a fertilizer program greatly benefitting agriculture. With time, opportunities and problems were encountered with utilization of soils. U of A soil scientists conducted inventories, conducted innovative research, developed superior management techniques, and through evolving education and extension, continuously helped bring improvements to how we utilized and managed soil resources. The DSS 100 yr evolution is chronicled under the themes of pedology (including soil survey), soil fertility, soil sustainability (conservation, land reclamation, and contaminant remediation), with embedded specialized studies within these themes.

Heavy Metal Immobilization Studies and Enhancement in Geotechnical Properties of Cohesive Soils by EICP Technique

Soil treatment methods to cope with ever-growing demands of construction industry and environmental aspects are always explored for their suitability in different in-situ conditions. Of late, enzyme induced calcite precipitation (EICP) is gaining importance as a reliable technique to improve soil properties and for contaminant remediation scenarios. In the present work, swelling and permeability characteristics of two native Indian cohesive soils (Black and Red) are explored. Experiments on the sorption and desorption of multiple heavy metals (Cd, Ni and Pb) onto these soils were conducted to understand the sorptive response of the heavy metals. To improve the heavy metal retention capacity and enhance swelling and permeability characteristics, the selected soils were treated with different enzyme solutions. The results revealed that EICP technique could immobilize the heavy metals in selected soils to a significant level and reduce the swelling and permeability. This technique is contaminant selective and performance varies with the nature and type of heavy metal used. Citric acid (C6H8O7) and ethylene diamine tetra-acetic acid (EDTA) were used as extractants in the present study to study the desorption response of heavy metals for different EICP conditions. The results indicate that calcium carbonate (CaCO3) precipitate deposited in the voids of soil has the innate potential in reducing the permeability of soil up to 47-fold and swelling pressure by 4-fold at the end of 21 days of curing period. Reduction in permeability and swell, following EICP treatment can be maintained with one time rinsing of the treated soil in water to avoid dissolution of precipitated CaCO3. Outcomes of this study have revealed that EICP technique can be adopted on selected native soils to reduce swelling and permeability characteristics followed by enhanced contaminant remediation enabling their potential as excellent landfill liner materials.

Order and Disorder in Layered Double Hydroxides: Lessons Learned from the Green Rust Sulphate - Nikischerite Series.

<div>Layered double hydroxides (LDHs) occur naturally and are synthesised for catalysis, drug</div><div>delivery and contaminant remediation. They consist of Me(II)-Me(III) hydroxide sheets</div><div>separated by hydrated interlayers and weakly held anions. Often, LDHs are nanocrystalline and</div><div>sheet stacking and Me(II)-Me(III) arrangement can be disordered, which influence reactivity and</div><div>complicate structural characterisation. We have used pair distribution function (PDF) analysis, to</div><div>provide detailed information about local and medium range order (< 9 nm), to determine the</div><div>structure of synthetic Fe(II)-Fe(III)/Al(III) LDH. The data are consistent with ordered Me(II)</div><div>and Me(III) in hydroxide sheets, where structural coherence along the c axis decreases with </div><div>increasing Al content. The PDF for Fe(II)-Al(III) LDH (nikischerite) is best matched by a</div><div>pattern for a single metal hydroxide sheet. Parallel to decreased structural coherence between</div><div>layers, coherence within layers decreased to ~6 nm for synthetic nikischerite. Thus, disorder</div><div>developed within and between the sheets, resulting in mosaic crystals with coherent scattering</div><div>domains decreasing in all directions. The high density of grain boundary terminations would</div><div>affect reactivity. Based on classical nucleation theory and the Kossel crystal growth model, we</div><div>propose that loss of structural coherence stems from increased supersaturation and the presence</div><div>of Al-hydroxides during formation of the Al-rich LDH</div>

Order and Disorder in Layered Double Hydroxides: Lessons Learned from the Green Rust Sulphate - Nikischerite Series.

<div>Layered double hydroxides (LDHs) occur naturally and are synthesised for catalysis, drug</div><div>delivery and contaminant remediation. They consist of Me(II)-Me(III) hydroxide sheets</div><div>separated by hydrated interlayers and weakly held anions. Often, LDHs are nanocrystalline and</div><div>sheet stacking and Me(II)-Me(III) arrangement can be disordered, which influence reactivity and</div><div>complicate structural characterisation. We have used pair distribution function (PDF) analysis, to</div><div>provide detailed information about local and medium range order (< 9 nm), to determine the</div><div>structure of synthetic Fe(II)-Fe(III)/Al(III) LDH. The data are consistent with ordered Me(II)</div><div>and Me(III) in hydroxide sheets, where structural coherence along the c axis decreases with </div><div>increasing Al content. The PDF for Fe(II)-Al(III) LDH (nikischerite) is best matched by a</div><div>pattern for a single metal hydroxide sheet. Parallel to decreased structural coherence between</div><div>layers, coherence within layers decreased to ~6 nm for synthetic nikischerite. Thus, disorder</div><div>developed within and between the sheets, resulting in mosaic crystals with coherent scattering</div><div>domains decreasing in all directions. The high density of grain boundary terminations would</div><div>affect reactivity. Based on classical nucleation theory and the Kossel crystal growth model, we</div><div>propose that loss of structural coherence stems from increased supersaturation and the presence</div><div>of Al-hydroxides during formation of the Al-rich LDH</div>