Evaluation of the Bioavailability and Translocation of Selected Heavy Metals by Brassica juncea and Spinacea oleracea L for a South African Power Utility Coal Fly Ash

Abstract

This study evaluated the physicochemical and mineralogical properties, mobile chemical species bioavailability and translocation in Brassica juncea and Spinacea oleracea L. plants of a South African coal-fired power utility. Coal-fly-ash (CFA) disposal is associated with various environmental and health risks, including air, soil, surface, and groundwater pollution due to the leaching of toxic heavy metals; these ends up in food webs affecting human health, while repeated inhalation causes bronchitis, silicosis, hair loss, and lung cancer. The morphology and chemical and mineralogical composition of CFA were determined using Scanning Electron Microscopy (SEM), X-ray fluorescence (XRF), and X-ray diffraction, respectively. In pot-culture experiments, S. oleracea L. and B. juncea plants were grown in three sets of pots containing CFA (Set 1), soil (Set 2), and a mixture of CFA plus soil at a ratio of 1:1 (50% CFA: 50% soil, Set 3), while no plants were grown in Set 4 as a control for the leachate samples. SEM showed that the surface morphology of CFA has a lower degree of sphericity with the irregular agglomerations of many particles. XRF results revealed that CFA contains 43.65%, 22.68%, and 10.89% of SiO2, Al2O3, and Fe2O3, respectively, which indicates that CFA is an aluminosilicate material. X-ray diffraction (XRD) showed that CFA contains mullite as a major phase, followed by quartz mineral phases. Chemical species such as B, Ba, Mo, and Cr were occurring at higher concentrations in the leachates for most weeks in the pot-culture experiments, especially for CFA and soil + CFA growth media. However, there was a common trend for all growth media of chemical-species concentrations declining with time, which might have been caused by plant uptake or wash-off with water during irrigation; even for the growth media as well, where no plants were grown. Chemical species, such as Fe, Mn, B, Ba, and Zn, accumulated highly in most parts of the plant species. However, B. juncea showed higher potential to accumulate chemical species as compared to S. oleracea L. Bioconcentration and translocation factors (BF and TF) showed that B. juncea was the most effective in terms of bioconcentration and translocation of most of the chemical species. This indicates that B. juncea has potential in application for the phytoremediation of CFA dumps, and could contribute to the remediation of CFA dumps and the reduction of potential health and environmental impact associated with CFA.

Effects of Wood Ash on Nutrients and Heavy Metal(oid)s Mobility in an Ultisol

“…When compared to the control, pH, EC, P, Ca, Mg, K, Na, Cu, and Zn significantly increased in the soil, in proportion to the WA dose, starting from 15 g kg −1 . These results are in line with various previous reports [22,23,24]. The pH increase can be primarily attributed to WA contents of Ca and Mg, which were very likely present as oxides and carbonates, as well as to the particle size of WA (<0.5 mm), which would favor solubilization.…”

Composition and Morphology Characteristics of Magnetic Fractions of Coal Fly Ash Wastes Processed in High-Temperature Exposure in Thermal Power Plants

“…XRD analysis is a well-defined technique, and used in most studies (e.g., Rivera, Kaur, Hesterberg, Ward, Austin and Duckworth [25], Kaur and Goyal [18], Kunecki, Panek, Koteja and Franus [32] and Mashau, Gitari and Akinyemi [14]) to assess the fly ash's mineralogical composition. In this study, we also conducted an XRD analysis of samples.…”

“…Fly ash's mineralogical composition mainly depends on the geological features that inform coal formation and deposition, as well as the combustion condition [13][14][15]. Here, quartz [14,[16][17][18][19], mullite [14,[20][21][22], hematite [19,[23][24][25], magnetite, and lime are the most common and predominant phases apart from other minor constituents [22,[25][26][27][28]. Also, fly ash's mineralogical composition is determined by the type of coal used.…”

“…As an important aspect of fly ash, morphology requires a thorough evaluation. It is well established that the particles of fly ash can be categorized in to eleven morphological groups based on the examination by light microscopy [10,14,20,32]. 'Char' is the most critical carbonaceous particle in fly ash that is formed when the coal particles are devolatilized.…”

The Effect of Mineral-Based Mixtures Containing Coal Fly Ash and Sewage Sludge on Chlorophyll Fluorescence and Selected Morphological Parameters of Deciduous and Coniferous Trees

“…Coal fly ash is produced in immense quantities in coal-fired power plants, and it constitutes a significant problem around the world [5]. Landfilling of fly ash from coal combustion poses a health risk and contributes to air, soil and water pollution by releasing leached heavy metals into the environment [6][7][8]. According to Ram and Masto [5], Krzaklewski et al [9] and Antonkiewicz et al [10], CFA has considerable potential for the reclamation of degraded areas, fallow land, defunct mining sites and landfills.…”