Recent trends in the use of fly ash for the adsorption of pollutants in contaminated wastewater and soils: Effects on soil quality and plant growth

Lead toxicity in plants: mechanistic insights into toxicity, physiological responses of plants and mitigation strategies

Soil toxicity is a major environmental issue that leads to numerous harmful effects on plants and human beings. Every year a huge amount of Pb is dumped into the environment either from natural sources or anthropogenically. Being a heavy metal it is highly toxic and non-biodegradable but remains in the environment for a long time. It is considered a neurotoxic and exerts harmful effects on living beings. In the present review article, investigators have emphasized the side effects of Pb on the plants. Further, the authors have focused on the various sources of Pb in the environment. Investigators have emphasized the various responses including molecular, biochemical, and morphological of plants to the toxic levels of Pb. Further emphasis was given to the effect of elevated levels of Pb on the microbial population in the rhizospheres. Further, emphasized the various remediation strategies for the Pb removal from the soil and water sources.

Managing antimony pollution: Insights into Soil-Plant system dynamics and remediation Strategies

Researchers are increasingly concerned about antimony (Sb) in ecosystems and the environment. Sb primarily enters the environment through anthropogenic (urbanization, industries, coal mining, cars, and biosolid wastes) and geological (natural and chemical weathering of parent material, leaching, and wet deposition) processes. Sb is a hazardous metal that can potentially harm human health. However, no comprehensive information is available on its sources, how it behaves in soil, and its bioaccumulation. Thus, this study reviews more than 160 peer-reviewed studies examining Sb's origins, geochemical distribution and speciation in soil, biogeochemical mechanisms regulating Sb mobilization, bioavailability, and plant phytotoxicity. In addition, Sb exposure effects plant physio-morphological and biochemical attributes were investigated. The toxicity of Sb has a pronounced impact on various aspects of plant life, including a reduction in seed germination and impeding plant growth and development, resulting from restricted essential nutrient uptake, oxidative damages, disruption of photosynthetic system, and amino acid and protein synthesis. Various widely employed methods for Sb remediation, such as organic manure and compost, coal fly ash, biochar, phytoremediation, microbial-based bioremediation, micronutrients, clay minerals, and nanoremediation, are reviewed with a critical assessment of their effectiveness, cost-efficiency, and suitability for use in agricultural soils. This review shows how plants deal with Sb stress, providing insights into lowering Sb levels in the environment and lessening risks to ecosystems and human health along the food chain. Examining different methods like bioaccumulation, bio-sorption, electrostatic attraction, and complexation actively works to reduce toxicity in contaminated agricultural soil caused by Sb. In the end, the exploration of recent advancements in genetics and molecular biology techniques are highlighted, which offers valuable insights into combating Sb toxicity. In conclusion, the findings of this comprehensive review should help develop innovative and useful strategies for minimizing Sb absorption and contamination and thus successfully managing Sb-polluted soil and plants to reduce environmental and public health risks.

Exploring the scientific research on coal fly ash and agriculture: knowledge mapping and future research directions

This paper aims at synthesizing the scientific research on coal fly ash and agriculture using bibliometric analysis. The research on fly ash and agriculture has grown at 6.7% annually during 1973-2022, where much attention has been received after 2007. The number of publications on coal fly ash and agriculture reached above 100 in the year 2010, which further increased to 299 by 2020. The research productivity has been assessed as the most influential countries, journals, and documents in terms of a number of publications and citations on fly ash and agriculture. India is the most productive country in terms of knowledge on coal fly ash and agriculture with 38% of the global publications, while Environmental Science and Pollution Research is the leading journal with 19 publications. The article on assessing the impact of fly ash incorporation in soil systems by Pandey and Singh (2010), having 349 citations with 26.85 citations per year is one of the leading publications globally. Further, science mapping has been conducted to comprehend the current research focus and discover the emerging themes for future research. The finding of the thematic map based on the level of development and importance indicate that FA can be effectively explored as soil-additive for improved physical, chemical and biological properties and enhanced plant nutrients. The findings provide several aspects of fly ash and suggest future research directions to study the potential of using coal fly ash in agriculture to gain an agronomic advantage.

Accumulation of pollutants from fly ash in Pleurotus ostreatus and a substrate based on coffee grounds by elemental analysis using the ICP-OES method and photometric method

The substrate mixtures were created in the study, using spent coffee grounds for Pleurotus ostreatus cultivation with the addition of straw and fluidized bed ash at 5 and 10 percent by weight relative to the total weight of coffee grounds. In order to determine the ability to accumulate heavy metals and the possibility of further waste management, analyses of micro- and macronutrients, biogenic elements, as well as the metal content of fungal fruiting bodies, mycelium and post-cultivation substrate were performed. The addition of 5 percent resulted in slower growth of mycelium and fruiting bodies, and with the addition of 10 percent, the growth of fruiting bodies was completely inhibited. The accumulation of elements such as (Cr), (Cu), (Ni), (Pb) and (Zn) was reduced in the fruiting bodies grown on the substrate with the addition of 5 percent fly ash, compared to spent coffee grounds without additives.

Adsorptive removal of phosphorus from aqueous solutions using natural and modified coal solid wastes

An invaluable utilization approach for industrial wastes is to employ them as effective adsorbents for environmental pollutants. This study aimed to investigate the phosphorus (P) adsorption behavior of coal wastes and zeolite in three forms of pristine powder (CP and ZP), nanoparticles (CNP and ZNP), and Fe (III)-modified nanoparticles (MCNP and MZNP). The adsorbents were characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) analyses. The effects of pH, initial P concentration, and contact time were studied under batch mode. Results showed an optimum pH range of 2-6 for the P adsorption process. The pseudo-second-order kinetic model and the Langmuir isotherm described the P adsorption data well. The P adsorption capacity of the studied adsorbents was enhanced after modifications. However, the coal-based modified adsorbents represented higher P adsorption performances rather than the zeolite ones. The maximum P adsorption capacity (Q_max) values were obtained as 0.36, 3.23, and 30.48 mg g^-1 for CP, CNP, and MCNP, and 0.80, 2.84, and 6.99 mg g^-1 for ZP, ZNP, and MZNP, respectively. The surface complexation, ligand exchange, and electrostatic attraction processes were identified as the main P adsorption mechanisms by the studied adsorbents.

Effects of different factors on fly ash-based functional soil and its oat grass cultivation

Using fly ash as the main matrix for plant ecological restoration is effective for constructing a sustainable and ecological environment. The relevant properties of functional soil change due to different factors. Based on the orthogonal experiment of functional soil and the pot experiment of oat grass, fly ash was used as the matrix material for functional soil. Afterward, MX (large granules dispensing certain nutrients), SJJXWS (a water-retaining agent), and AF (a nutrient conditioner) additives were added to study the physical, chemical, and agronomic properties of functional soil, such as the emergence rate and weight of plants. The results showed the high pH and conductivity of functional soil, implying alkaline soils with high salinity. The contents of organic matter and available phosphorus and potassium were relatively high, indicating its high nutrient content. Further analysis revealed that the MX was the key factor affecting functional soil's electrical conductivity and evaporation, and thus, the corresponding plant emergence rate, plant weight, and other related indicators. The influence of each factor on the corresponding plant emergence rate, plant weight, and other indicators of functional soil was arranged in the order of MX (large granules dispensing certain nutrients), SJJXWS (a water-retaining agent), and AF (a nutrient conditioner). The optimum additive ratio in functional soil was 0.45 t·hm^-2 of MX, 0.12 t·hm^-2 of SJJXWS, and 1.65 t·hm^-2 of AF. The results of this study provide a theoretical basis for further development of functional soil for ecological cycle restoration purposes.

Nano-Restoration for Sustaining Soil Fertility: A Pictorial and Diagrammatic Review Article

Soil is a real treasure that humans cannot live without. Therefore, it is very important to sustain and conserve soils to guarantee food, fiber, fuel, and other human necessities. Healthy or high-quality soils that include adequate fertility, diverse ecosystems, and good physical properties are important to allow soil to produce healthy food in support of human health. When a soil suffers from degradation, the soil’s productivity decreases. Soil restoration refers to the reversal of degradational processes. This study is a pictorial review on the nano-restoration of soil to return its fertility. Restoring soil fertility for zero hunger and restoration of degraded soils are also discussed. Sustainable production of nanoparticles using plants and microbes is part of the process of soil nano-restoration. The nexus of nanoparticle–plant–microbe (NPM) is a crucial issue for soil fertility. This nexus itself has several internal interactions or relationships, which control the bioavailability of nutrients, agrochemicals, or pollutants for cultivated plants. The NPM nexus is also controlled by many factors that are related to soil fertility and its restoration. This is the first photographic review on nano-restoration to return and sustain soil fertility. However, several additional open questions need to be answered and will be discussed in this work.