Browsing by Author "Darko, D.A."
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Item Accumulation of heavy metals and human health risk assessment of vegetable consumption from a farm within the Korle lagoon catchment(Heliyon, 2023) Osae, R.; Nukpezah, D.; Darko, D.A.; Koranteng, S.S.; Mensah, A.The Korle lagoon is known to have high concentration of heavy metals. The use of land for agriculture and water for irrigation within the Korle Lagoon’s catchment constitutes a potential health risk. Due to this, the study assessed the concentration of heavy metals in some vegetables (Amaranth, Spinach, Eggplant, Lettuce, Cauliflower, and Onion) and their corresponding soil from a farm within the Korle Lagoon’s catchment. The estimated daily intake (EDI), hazard quotient (HQ), and lifetime cancer risk (LCR) was used to assess their health risks. Among the vegetables tested, heavy metals in lettuce exceeded their recommended guideline level. Additionally, the concentrations of Fe (265.94–3599.60 mg/kg) and Zn (76.77–294.70 mg/kg) in all vegetables were above the recommended guideline level. Also, Zn (227.30–534.57 mg/kg) and Pb (101.53–407.58 mg/kg), in soil were above the recommended guideline level for soil. The results also showed not only the severity of heavy metal pollution of soil in the study area, but also risks that were deemed carcinogenic and noncarcinogenic to both adults and children as a result of consumption of vegetables from the study area. The hazard index for adults (0.46–41.156) and children (3.880–384.122), were high for all vegetables tested and are associated with cancer risk due to high Cr and Pb levels. The risk assessment showed that children may suffer more carcinogenic and noncarcinogenic health risk than adults. The study concluded that vegetables grown within the Korle lagoon’s catchment is not suitable for consumption due to the associated adverse health effect.Item Heavy metal mobility, bioavailability, and potential toxicity in sediments of the Korle lagoon in Ghana(Taylor & Francis Group, 2022) Osae, R.; Nukpezah, D.; Darko, D.A.; Mensah, A.This study aimed to identify the mobility, bioavailability, and potential toxicity of heavy metals (HM) in sediments of the Korle lagoon using metal partition. Sediments were analysed using the BCR (Bureau of reference) method. As (60%), Pb (50%), Zn (57%) and Fe (40%) were found in high concentration in the ion exchangeable fraction. The oxidisable fraction was dominated by Cu (51%), Cd (95%), Cr (61%), Ni (63%), As (35%), Fe (21%), Hg (30%), Pb (19%) and Zn (11%). The reducible fraction was dominated by Zn (29%), Pb (24%) and Hg (19%). The residual fraction was dominated by Hg (49%) and Fe (34%). PCA was used to identify pH and organic matter as the most important factors controlling the mobility and bioavailability of HM in the sediments. Arsenic, Pb, Zn and Fe were found to have the highest mobility. Chromium, Cu and Ni have medium mobility. Hg has low mobility. Most of the HM show potential bioavailability and toxicity.Item Influence of method of residue application and moisture content on water soluble nitrogen in a rhodickandiustalf amended with different fallow plant materials(West African Journal of Applied Ecology, 2019-10-05) Darko, D.A.; Nartey, E.K.; Adiku, S.; Laryea, K.B.Use of plant residues as nutrient sources presents a viable option to resource poor farmers who sparsely use mineral fertilizer in crop production. A study was conducted to gain an insight into how different application methods of residues from different fallow management systems under two moisture regimes would affect soluble N release in a Rhodic Kandiustalf. Three residue types viz, elephant grass from a natural fallow (T1) and another as a fallow following a previously fertilized maize (T2) and a fallow legume (T3) were surface applied and incorporated in a Rhodic Kandiustalf at both field capacity (FC) and 60% field capacity over a sixteen-week period. Incorporation of mucuna residues and elephant grass from previously fertilized maize fallow released similar soluble N levels which were higher than levels from the natural elephant grass amendments. At 60% FC, both mucuna and elephant grass from the fertilized maize fields that were surface applied had slower N releases than the grass from the natural fallow, suggesting the elephant grass from the natural fallow field could be used as an N source amidst light watering to avoid leaching in the dry season.Item An Investigation Of Agrochemical Transport Mechanisms In Some Cultivated Soils In Ghana(University of Ghana, 2015-07) Darko, D.A.The study basically examined the movement of agrochemical compounds in soil. Four different soil samples made up of three sandy loams and a sandy clay were used in the study. Potassium chloride solution and chlorpyrifos were used as infiltration solutions in a horizontal infiltration study under laboratory conditions. At the end of each experiment, the infiltration column was sectioned and the moisture content as well as the solution concentration of the agrochemical compound (Cl-, K+, and chlorpyrifos) contents determined. The water content, Cl-, K+ and chlorpyrifos contents profiles preserved similarity with regards to the variable . Moisture diffusivity and dispersion coefficients were therefore considered to be dependent on water content only. The moisture diffusivity function and the dispersion coefficients of the solutes were derived using the θ(λ) and c(λ) data together with the Continuous System Modeling Program (CSMP) computer program. The moisture diffusivity values obtained showed that the sandy loams due to their large pore sizes permitted higher infiltration of water than the sandy clay. With the exception of the Xanthic Ferrasol and Ferric Lixisol, which are sandy loam, the chloride profiles moved ahead of the profiles of water and the other solutes. The chloride concentration front measured in the Ferrasol and Lixisol lagged behind that of the water, thus suggesting chloride mobility was retarded during the infiltration experiment. Differences in the notional planes of chloride and water used as influent solutions in the infiltration experiments also suggests the existence of immobile water content in the sandy clay and one of the sandy loams. Estimation of the dispersion coefficient of chloride in the two soils in which immobile water content was established suggests that chloride dispersion was low when immobile water content was accounted for in the estimation of the dispersion coefficient.Item Pesticides Bioconcentration Potential of Aquatic Plants in the Volta Lake(West African Journal of Applied Ecology, 2018) Koranteng, S.S.; Darko, D.A.; Nukpezah, D.; Ameka, G.K.The Volta Lake is known for the proliferation of numerous aquatic plants in its shallow waters. A major cause for the presence of the luxuriant vegetation is the intensive agricultural activities along the banks. These activities are heavily dependent on agrochemicals including fertilizers, which eventually get into the aquatic ecosystem via water ways. In this study, two aquatic plants; Ceratophyllum demersum and Nymphaea lotus were investigated in a pilot study to determine their bioconcentration of pesticides. Levels of organochlorine (OCs) and synthetic pyrethroids (SPs) were analysed using gas chromatograghy equipped with electron capture detector while gas chromatography equipped with pulse flame photometric detector was used for the organophosphorus pesticides (OPs) determination in the plant tissues. The ambient concentrations of these pesticides in the aqueous medium were also determined and the ratios of pesticide concentration in the plant and water samples estimate bioconcentration potential of the plants. Out of 38 detected pesticides, 22 (representing 58%) were bioconcentrated by the aquatic weeds. The Bioconcentration Factor (BCF) range for Ceratophyllum demersum was 1.06 – 4,470 and that for Nymphaea lotus was 1.27 – 800. By the standard of the European Union regulation for registration of chemicals, levels of diazinon and chlorpyrifos in Ceratophyllum demersum fulfilled the ‘bioaccumulation’ criterion (i.e BCF > 2000) while fenitrothion, with BFC of 5500 in the same plant fulfilled ‘very bioaccumulation’ criterion (BCF ≥ 5000). This study shows that aquatic weeds in their natural ecosystem have the remediation potential, though to varying degrees and hence play a role in the improvement of water quality.Item Synthesis of Three-Dimensional Reduced-Graphene Oxide from Graphene Oxide(Hindawi, 2022) Singh, R.; Ullah, S.; Rao, N.; Singh, M.; Patra, I.; Darko, D.A.; Issac, C.P.J.; Esmaeilzadeh-Salestani, K.; Kanaoujiya, R.; Vijayan, V.Carbon materials and their allotropes have been involved significantly in our daily lives. Zero-dimensional (0D) fullerenes, onedimensional (1D) carbon materials, and two-dimensional (2D) graphene materials have distinctive properties and thus received immense attention from the early 2000s. To meet the growing demand for these materials in applications like energy storage, electrochemical catalysis, and environmental remediation, the special category, i.e., three-dimensional (3D) structures assembled from graphene sheets, has been developed. Graphene oxide is a chemically altered graphene, the desired building block for 3D graphene matter (i.e., 3D graphene macrostructures). A simple synthesis route and pore morphologies make 3D reduced-graphene oxide (rGO) a major candidate for the 3D graphene group. To obtain target-specific 3D rGO, its synthesis mechanism plays an important role. Hence, in this article, we will discuss the general mechanism for 3D rGO synthesis, vital procedures for fabricating advanced 3D rGO, and important aspects controlling the growth of 3D rGO.