monitoring-pedogenic-inorganic-carbon-accumulation-due-to-weathering

Monitoring Pedogenic Inorganic Carbon Accumulation Due to Weathering of Amended Silicate Minerals in Agricultural Soils.

The present study aims to demonstrate a systematic procedure for monitoring inorganic carbon induced by enhanced weathering of comminuted rocks in ...

University of Guelph

The rapid proliferation of cyanobacteria in bodies of water has caused cyanobacterial blooms, which have become an increasing cause of concern, largely due to the presence of toxic secondary metabolites (or cyanotoxins). Cyanotoxins are the toxins produced by cyanobacteria that may be harmful to surrounding wildlife. They include hepatotoxins, neurotoxins and dermatotoxins, and are classified based on the organs they affect. There are also non-toxic secondary metabolites that include chelators and UV-absorbing compounds. This paper summarizes the optimal techniques for secondary metabolite extraction and the possible useful products that can be obtained from cyanobacteria, with additional focus given to products derived from secondary metabolites. It becomes evident that the potential for their use as biocides, chelators, biofuels, biofertilizers, pharmaceuticals, food and feed, and cosmetics has not yet been comprehensively studied or extensively implemented.

Extraction and applications of cyanotoxins and other cyanobacterial secondary metabolites.

To lock atmospheric CO at anthropogenic timescale, fast weathering silicates can be applied to soil to speed up natural CO sequestration via enhanced weathering. Agricultural lands offer large area for silicate application, but expected weathering rates as a function of soil and crop type, and potential impacts on the crops, are not well known. This study investigated the role of plants on enhanced weathering of wollastonite (CaSiO) in soils. Using rooftop pot experiments with leguminous beans ( L.) and nonleguminous corn ( L.), CO sequestration was inferred from total inorganic carbon (TIC) accumulation in the soil and thermogravimetric analysis, and mineral weathering rate was inferred from alkalinity of soil porewater. Soil amendment with wollastonite promoted enhanced plant growth: beans showed a 177% greater dry biomass weight and corn showed a 59% greater plant height and a 90% greater dry biomass weight. Wollastonite-amended soil cultivated with beans showed a higher TIC accumulation of 0.606 ± 0.086%, as compared to that with corn (0.124 ± 0.053%). This demonstrates that using wollastonite as a soil amendment, along with legume cultivation, not only buffers the soil against acidification (due to microbial nitrogen fixation) but also sequesters carbon dioxide (12.04 kg of CO/tonne soil/month, 9 times higher than the soil without wollastonite amendment).

Co-Benefits of Wollastonite Weathering in Agriculture: CO Sequestration and Promoted Plant Growth.

Carbon dioxide (CO) is a major greenhouse gas, and its concentration in the atmosphere is increasing continuously, hence there is an urgent need to reduce its level in the atmosphere. Soils offer a large natural sink to store CO. This study focuses on sequestering CO in the agricultural soils as inorganic carbon, which can be accomplished by adding alkaline-earth silicates. Wollastonite is used in this study as a soil amendment, to sequester CO the geochemical route of mineral carbonation. The first objective of the present study was to evaluate the effect of mixing a wide range of dosages of wollastonite, as a soil amendment, on the growth performance of two leguminous plants frequently used in agricultural sector: soybean and alfalfa. The plants were grown with different wollastonite dosages (3-20 kg·m for soybean and 3-40 kg·m for alfalfa), for a duration of 14 weeks in a microplot experiment in Ontario, Canada. The second objective was to find evidence of enhanced weathering of wollastonite in soil, in addition to the augmentation of inorganic carbon content in soil. For this, mineralogical assessment of the soils was performed using XRD and SEM-EDS analyses. Wollastonite increased the soybean yield by two-fold in the plot amended with 10 kg·m. At all dosages, wollastonite increased the alfalfa growth in terms of height and above-ground biomass dry weight, as well as root biomass. The rate of CO sequestration, at optimum wollastonite dosage, reached 0.08 kg CO·m·month. XRD and SEM-EDS analyses indicated accumulation of calcite in wollastonite-amended soil and formation of other weathering products. The results obtained from this study help to understand the impact of wollastonite soil amendment on agronomy, and will aid in implementing such negative emissions technology by informing farmers and industry alike that the use of wollastonite contributes toward global climate change mitigation while supporting crop yield. The findings of this study add to the existing body of knowledge on enhanced weathering as an atmospheric CO removal technology, providing further evidence that wollastonite weathering in agricultural soils can lead to significant capacity for CO sequestration as inorganic carbon, while concurrently promoting plant growth.

Article	Year
Extraction and applications of cyanotoxins and other cyanobacterial secondary metabolites. Chemosphere\| PubMed ID: 28544902	2017
Co-Benefits of Wollastonite Weathering in Agriculture: CO Sequestration and Promoted Plant Growth. ACS omega\| PubMed ID: 30775646	2019
Optimizing Inorganic Carbon Sequestration and Crop Yield With Wollastonite Soil Amendment in a Microplot Study. Frontiers in plant science\| PubMed ID: 32719708	2020

Fatima Haque

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