by Peter Oyelade Ogungbile, Adefemi Olatayo Ajibare, Adebisi Esther Enochoghene, Timothy Oyebamiji Ogunbode, Olumide Ekundayo Omotayo Omotayo, Christiana Tinuola Ekanade, Mynepalli Kameswara Chandra Sridhar, John Adebayo Akande

Trop. Aqua. Soil Pollut. 2024, 4(1), pp 1-9; https://doi.org/10.53623/tasp.v4i1.343

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Abstract This study assessed the phytoremediation potential of sunflowers for removing cadmium from the soil around a paint manufacturing industry in Eleyele, Ibadan. Background levels of Cd in the topsoil and subsoil were determined. The site was divided into two plots. Organo-mineral fertilizer (OMF) was applied to the first plot, which served as the experimental plot, while the second plot was without OMF and served as the control. Concentrations of cadmium in the plants were determined using an Atomic Absorption Spectrophotometer. Baseline mean Cd contents were 29.23 mg/kg and 33.30 mg/kg for topsoil and subsoil, respectively. Over the planting period, the sunflower plants removed 53.1% and 51.6% of Cd from the topsoil and subsoil in the test plot, while 40.65% and 47.80% were removed from the topsoil and subsoil, respectively, in the control. Cd absorption from the contaminated soils was found to be translocated to all parts of the sunflower. The concentrations of Cd in the sunflower parts were as follows: root system (10.70 mg/kg), shoot (8.17 mg/kg), leaves (6.43 mg/kg), and seeds (2.52 mg/kg) for the test plot. For the control plots, Cd in the root, shoot, leaves, and seeds were 7.60 mg/kg, 7.43 mg/kg, 4.75 mg/kg, and 2.03 mg/kg, respectively. The study confirmed that sunflowers have the potential to remediate Cd from contaminated soil, and this potential was enhanced by the application of OMF.[...] Read more. Full text

by Samuel Sunday Ogunsola, Adedeji Adebukola Adelodun, Mary Bosede Ogundiran

Trop. Aqua. Soil Pollut. 2024, 4(1), pp 27-42; https://doi.org/10.53623/tasp.v4i1.398

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Abstract Following phytoremediation, the disposal of accumulating plants (phytoaccumulators) is challenging because the accumulated metals could leach back into the soil if not properly managed. Therefore, this study aims to use calcined clay (CC)-based geopolymer to stabilize Pb, Cu, and Zn in a phytoaccumulator (Sporobolus pyramidalis) ash (PA). Additionally, the effect of adding PA on the setting time, mechanical and heavy metals leaching properties of the geopolymers was investigated, to determine their environmental suitability and potential applications. Mixed proportions of CC (85-100%) and PA (5% - 15%) were used to produce geopolymers, using 8 M NaOH/Na₂SiO₃ (1:1) as an alkaline activator. The geopolymers were cured for 7 and 28 days at ambient temperatures. Thermograms showed the dehydroxylation of kaolinite at 450-650 °C. X-ray flourescene (XRF) analysis showed CC’s predominant oxides as SiO₂ (53.1%) and Al₂O₃ (41.4%), while PA exhibited SiO₂ (46.6%), CaO (13.8%), PbO (1.30%), ZnO (0.28%), and CuO (0.04%). Thermal treatment eliminated most FTIR bands associated with kaolinite, converting crystalline kaolinite into amorphous metakaolinite. Geopolymer setting time ranged from 75 min (100% CC) to 111 min (85% CC). Furthermore, elevated Cao content in the PA resulted in the geopolymer’s early strength development. However, the compressive strength decreased as PA quantity increased, with 95% CC-PA exhibiting maximum strength (22.5 ± 0.2 MPa) after 28 days. Further tests confirmed that 95% and 90% CC-PA geopolymer effectively stabilized Pb and Cu. Fabricated geopolymers met the ASTM (C62-17) Specification Standard for building brick, indicating their suitability as a waste-based construction material under controlled conditions.[...] Read more. Full text

by Rubiyatno, Aulia Maulana, Jovale Vincent Tongco, Arma Yulisa, Sang Hyeok Park, Md Abu Hanifa Jannat, Rega Permana, Ocean Thakali, Michael Lie, Aouatif Fahssi, Ouahiba Aziez, Camilo Bastidas

Trop. Aqua. Soil Pollut. 2024, 4(1), pp 10-26; https://doi.org/10.53623/tasp.v4i1.403

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Abstract Chlorpyrifos (CP) is a widely used organophosphate pesticide known for its recalcitrant nature, raising concerns about potential ecological and health impacts due to its toxicity. Many plants and animals are contaminated with this pesticide. Microbial biodegradation offers an environmentally friendly and effective method to remove CP from the environment and mitigate its impacts, especially given its low cost, particularly when bioremediation is conducted on-site. Different types of microbial species have been found to function under various environmental conditions, with some, like Pseudomonas nitroreducens PS-2 and Pseudomonas aeruginosa (NCIM 2074), showing promising results with degradation rates of up to 100%. However, challenges exist, such as partial degradation caused by the presence of metabolites, and the recalcitrant nature of CP, which can impede microbes' ability to effectively degrade its hydrocarbon ring. Overall, a combination of approaches, such as microbial and algal methods, or the discovery of new microbial strains, can help overcome these challenges and further enhance the long-term viability of this technique.[...] Read more. Full text