Heavy Metals Concentration in Rhizosphere and Tissues of Smooth Pigweed (A. hybridus) and Bush Okra (C. olitorius) cultivated on an Abandoned Dumpsite

The study assessed the concentrations of Pb, Cr, and Cd in rhizosphere and tissues of A. hybridus and C. olitorius grown on a dumpsite converted to farmland by plant and 0-15 cm depth soil samples which were air-dried, digested and analysed using Atomic Absorption Spectrophotometry. Some physiochemical parameters that affect transport of soil nutrients into plant tissues were analysed using standard methods. The pH of the rhizosphere soil of C. olitorius was 6.71 and the soil of A. hybridus was slightly alkaline in nature with pH 7.75. The rhizosphere of A. hybridus had the highest concentration of Pb (123.20±90.04 mg/kg) and Cd (0.63±0.63 mg/kg) while Cr was highest in the rhizosphere of C. olitorius (36.57±8.61 mg/kg). The result showed total and bioavailable metal concentrations in the soils were in the order of Pb > Cr > Cd. The order of metal uptake varied with vegetable crop. Metal concentration in tissues of A. hybridus followed the order of Pb > Cr > Cd while C. olitorius was Cr > Pb > Cd. Concentrations of Cd, Pb and Cr exceeded the maximum permissible limit in soil and within allowable limit in the tissue. C. olitorius had transfer factor (TF) < 1 for Cd, Pb and Cr. A. hybridus had similar transfer factor except for Cr with TF > 1. The study concluded that the dumpsite converted to farmland is highly contaminated with Pb, Cr, and Cd and highly accumulated by the vegetables.Keywords: Heavy metals, dumpsite, Transfer factor, vegetables

Effects of Petroleum Products on the Chlorophyll Accumulation in Barbula lambarenensis

The effects of petroleum products: Petroleum Motor Spirit (petrol, PMS), Automobile Gas Oil (diesel. AGO), Dual Purpose Kero (kerosene, DPK), were investigated on the chlorophyll accumulation in Barbula lambarenensis. This plant with its substrates were collected from its natural populations, taken to the screen house and divided into ten regimes widely separated. Each of these regimes was irrigated with borehole water for two weeks, thrice a week to bring about hydration. The three petroleum products were separately diluted with borehole water in 1:1 ratio to give 50% concentrations. Moreover, 100% of these products were also used .The 50% concentrations were separately used to irrigate the first three regimes, A, B and C for 20 weeks .The D, E and F regimes were irrigated with 100% kerosene, petrol and diesel respectively for the 2 weeks and later with borehole water for twenty weeks while the G regime was irrigated with borehole water (Control). Irrigations were done thrice a week. Samples of B. lambarenensis were collected fortnightly for chlorophyll extraction and the chlorophyll a, b and total chlorophyll content determined with the aid of spectrophotometer .It was observed that the 50% treated moss plants had greater chlorophyll a, b and total chlorophyll than the control but their concentrations were statistically the same. The 100% treatment gave greater chlorophyll a content than the control, PMS treatment had greater chlorophyll b than the control but the reverse were for DPK and AGO treated moss plant. However, all these values were the same statistically. The same results were found for the total chlorophyll except that the DPK, AGO and Control treatments had the same value statistically while DPK, Control and PMS treatments were the same statistically. The 50% treatments had worse effects than the 100% followed by borehole water treatments. Furthermore, the two concentrations had the same effects on the chlorophyll contents but DPK and AGO had significantly greater chlorophyll b concentrations in 50% treated regimes than 100% treatments at 5% level of significance. Petroleum products damaged the chlorophyll apparatus of the plant making the treated to produce greater chlorophyll contents than the Control

Influence of Tree Characters and Climate on Litter Characteristics in Daniellia oliveri (Rolfe) Hutch. & Dalziel

Litter production and decomposition rates have great importance inmaintaining the fertility of the soil. The study was carried out to determine the relationship tree characters (girth size, canopy radius, tree height, leaf area and number of primary branches), litter production and quality, and climatic variables among stands of Daniellia oliveri (Rolfe) Hutch. & Dalziel growing in University of Ilorin campus. Twelve trees of different girth sizes were selected and their physiognomic characters measured. Litter samples(leaves and twigs) were collected from the stands on monthly basis  (January to May) using 1 m2 traps. The collected litters were air-dried, ground and analysed for carbon, nitrogen, phosphorus, potassium, calcium and magnesium using standard methods. Rainfall and temperature data were collected during the sampling months. Girth size range was 0.32 – 0.67 m. Tree height range was 13.90 – 31.81 m. Primary branches range was 3 - 16, crown radii was 2.5 - 5.2 m and leaflet area between 24.62 cm2 and 90.90 cm2. Higher leaf litter was recorded in January and February, but twigs were more in the other months. Leaf and twig litters positively  correlated with girth size (r = 0.572 and 0.614 respectively), but the formeralso correlated with crown radii (r = 0.834). Carbon, calcium and  magnesium contents in leaves and twigs were lower in May compared to January, but reverse trend were observed for nitrogen and phosphorus. The number of rain (rainy days) negatively correlated with total monthly litter (r = -0.291). The study concluded that climatic conditions influence tree characters, which in turn affect litterfall and nutrient returns to the soil. ©JASE

Computational Dynamics of Anti-Corrosion Performance of Laser Alloyed Metallic Materials

Laser surface alloying (LSA) is a material processing technique that utilizes the high power density available from defocused laser beam to melt both reinforcement powders and a part of the underlying substrate. Because melting occurs solitary at the surface, large temperature gradients exist across the boundary between the underlying solid substrate and the melted surface region, which results in rapid self-quenching and resolidifications. Reinforcement powders are deposited in the molten pool of the substrate to produce corrosion-resistant coatings. These processes influence the structure and properties of the alloyed region. A 3D mathematical model is developed to obtain insights on the behavior of laser melted pools subjected to various process parameters. It is expected that the melt pool flow, thermal and solidification characteristics will have a profound effect on the microstructure of the solidified region

Mobility and Transport of Inorganic Species in Weathered Hydraulic Disposed Coal Fly Ash: An Insight from Geochemical Fractionation and Statistical Evaluation

A large volume of coal fly ash generated through combustion process has raised environmental concerns due to possible release of potentially toxic species to the surface and groundwater systems. The chemical partitioning and mobility of elements in the hydraulic disposed ash dump was investigated using modified sequential extraction scheme. The geochemical distribution of the investigated elements in 33 drilled core samples was determined by x-ray fluorescence and inductively coupled plasma mass spectrometry. The ternary plot of major elements as determined by XRF showed that hydraulic disposed ash cores are sialic, ferrosialic and ferrocalsialic in chemical composition. The relationship between SiO2 and chemical index of alteration (CIA) showed low, moderate to high degree of weathering. These chemical compositions and degree of chemical weathering depend on the ash sampling point and ash interaction chemistry. The Na+ and K+ soluble salts showed evidence of leaching and downward migration in the water soluble fraction indicating that the hydraulic disposed ash dump is not a sustainable salt sink. The geochemical partitioning reveals that mobility and transport of potentially toxic metal species are governed by the pore water pH, ash interaction chemistry and the sampling point of the ash cores.  The chemical interaction of drilled core ash with the ingress CO2 and percolating rain water led to dissolution and co-precipitation of soluble major components in fly ash. This had led to incoherent patterns of elements in carbonate fraction of the ash cores.Key words: Modified sequential extraction; Hydraulic disposed ash; Chemical index of alteration; Pore water pH; Ash interaction chemistry; Moisture content; Chemical weatherin

Influence of Tree Characters and Climate on Litter Characteristics in Daniellia oliveri (Rolfe) Hutch. & Dalziel

Litter production and decomposition rates have great importance in maintaining the fertility of the soil. The study was carried out to determine the relationship tree characters (girth size, canopy radius, tree height, leaf area and number of primary branches), litter production and quality, and climatic variables among stands of Daniellia oliveri (Rolfe) Hutch. & Dalziel growing in University of Ilorin campus. Twelve trees of different girth sizes were selected and their physiognomic characters measured. Litter samples (leaves and twigs) were collected from the stands on monthly basis (January to May) using 1 m2 traps. The collected litters were air-dried, ground and analysed for carbon, nitrogen, phosphorus, potassium, calcium and magnesium using standard methods. Rainfall and temperature data were collected during the sampling months. Girth size range was 0.32 \u2013 0.67 m. Tree height range was 13.90 \u2013 31.81 m. Primary branches range was 3 - 16, crown radii was 2.5 - 5.2 m and leaflet area between 24.62 cm2 and 90.90 cm2. Higher leaf litter was recorded in January and February, but twigs were more in the other months. Leaf and twig litters positively correlated with girth size (r = 0.572 and 0.614 respectively), but the former also correlated with crown radii (r = 0.834). Carbon, calcium and magnesium contents in leaves and twigs were lower in May compared to January, but reverse trend were observed for nitrogen and phosphorus. The number of rain (rainy days) negatively correlated with total monthly litter (r = -0.291). The study concluded that climatic conditions influence tree characters, which in turn affect litterfall and nutrient returns to the soil

Modelling and Optimization of Laser Alloyed AISI 422 Stainless Steel Using Taguchi Approach and Response Surface Model (RSM)

This research paper demonstrates the application of Taguchi method and Response surface Methodology (RSM) for optimization of alloyed depth in laser alloying of AISI 422 martensitic stainless steel. The experiment was designed and carried out on the basis of standard L9 Taguchi’s orthogonal array in which three laser processing parameters such as laser power, scanning speed and powder feed rate were arranged at three levels. The processing parameters played an important role in the quality of alloyed coating produced and proper control of these processing parameters resulted in quality alloyed depth and hardness property. From the analysis of mean values of variance (ANOVA) and response surface numerical analysis, the significant laser processing parameters were indentified. The results showed that laser power and scanning speed are the most significant parameters affecting the alloyed depth of laser surface alloying (LSA), while the influence of powder feed rate is much minimal

Silicone oil as corrosion inhibitor for aluminium alloy in saline medium

Corrosion processes are responsible for huge losses in the industry. This deterioration of components results in loss of plant efficiency, total shutdown and aggressive damage in industries. Though organic, inorganic and mixed material inhibitors were used for a long time to combat corrosion, the environmental toxicity of inorganic corrosion inhibitors has prompted the search for organic corrosion inhibitors. In the search for this, the present study aims to investigate the inhibition action of silicone oil and their protective performance for aluminium alloy in 3.5% NaCl solution using electrochemical tests. Weight loss, corrosion rate, inhibition efficiency and potentiodynamic polarisation techniques were used in this study. The aluminium alloy samples exposed to the inhibitor showed a lower corrosion rate values and excellent polarisation resistance as compared with the corrosion rate samples without inhibitor. The corrosion inhibition rate increases with increasing the concentration of the silicone oil. The adsorption isotherm was confirmed by Langmuir adsorption isotherm

Laboratory study on the mobility of major species in fly ash–brine co-disposal systems: up-flow percolation test

Apart from the generation of fly ash, brine (hyper-saline wastewater) is also a waste material generated in South African power stations as a result of water re-use. These waste materials contain major species such as Al, Si, Na, K, Ca, Mg, Cl and SO4. The co-disposal of fly ash and brine has been practiced by some power stations in South Africa with the aim of utilizing the fly ash to capture the salts in brine. The effect of the chemical interaction of the species contained in both fly ash and brine, when co-disposed, on the mobility of species in the fly ash–brine systems is the focus of this study. The up-flow percolation test was employed to determine the mobility of some major species in the fly ash–brine systems. The results of the analysed eluates from the up-flow percolation tests revealed that some species such as Al, Ca and Na were leached from the fly ash into the brine solution while some species such as Mg, Cl and SO4 were removed to some extent from the brine solution during the interaction with fly ash. The pH of the up-flow percolation systems was observed to play a significant role on the mobility of major species from the fly ash–brine systems. The study showed that some major species such as Mg, Cl and SO4 could be removed from brine solution using fly ash when certain amount of brine percolates through the ash.Web of Scienc

TIG Welding Methods of Repairing Steel Components with Stainless Steel Coatings

Structural steel components tend to wear when exposed to corrosive and cyclic loading environments. These components can be repaired by welding on failure. This study studied the weld parameters and weld quality (porosity, depth of penetration, and coating thickness), hardness, corrosion, and wear resistance during repair welding. Mild steel samples were weld coated by varying alternating (AC) and direct (DC) currents: 40 A, 50 A, 55 A, 60 A, 65 A, and 70 A. The base material used was AISI 1045 steel, and Castolin 6825 was used as the welding electrode. The results showed that three wear mechanisms were dominant: abrasion, adhesion, and delamination. The porosity in the coated samples increased with increasing currents for both AC and DC. The welding current and current type influenced the coating thickness and penetration depth. When dipped in warm NaCl solution, the corrosion mechanism experienced by both sets of coated samples was pitting corrosion. In both cases (alternating and direct currents), the hardness values increased towards the coating surface from the substrate