Phytoremediation of diesel and spent engine oil contaminated soil using Kariya (Hildergardia barteri Mast.) seedlings

Using a completely randomized design experiment, the effect of different levels of diesel and spent engine oil contamination (0 mL/kg, 25 mL/kg, 50 mL/kg and 75 mL/kg of soil) on growth performance (seedling height, collar diameter, number of leaves and biomass accumulation) of Hildergardia barteri seedlings were assessed for twelve weeks. The concentration of Lead, Nickel, Copper and Zinc in the plant parts were also determined. Data were analysed using descriptive and inferential statistics at P<0.05 level of significance. There were significant differences in the effects of diesel and spent engine oil on growth performance of seedlings based on contamination levels. Control treatment had the highest height (92.43±5.13 cm), collar diameter (16.23±0.98 mm), number of leaves (11.21±0.47) and total biomass (33.01±12.79 g). Seedlings exposed to 50 mL/kg treatments had the least height (diesel oil: 78.21±7.22 cm; spent engine oil: 79±6.24 cm); those exposed to 75 mL/kg contamination had the least collar diameter (diesel oil: 8.85±1.05 mm, spent engine oil: 12.02±1.01 mm), while seedlings treated with 50 mL/kg diesel oil (2.21±0.37) and 75 mL/kg spent engine oil (4.79±0.55) had the lowest number of leaves. Heavy metal bio-accumulation ranges were: Lead: 0.17-0.39 mg/kg, Nickel: 0.09–0.45 mg/kg, Copper: 0.54–1.08 mg/kg, Zinc: 0.88–1.58 mg/kg. The ability of the seedlings to survive and bio-accumulate heavy metals indicate the potential phytoremediation capabilities of Hildergardia barteri. Keywords: phytoextraction, hydrocarbon derivatives, growth inhibition, Hildergardia barter

Compressive strength in Heartwood Extract of Teak (HWE) treated hardwoods after exposure to white rot attack

Wood samples of Triplochiton scleroxylon and Gmelina arborea obtained from Omo Forest Reserve, South West Nigeria were treated with Heartwood Extract of Teak (HWE) and cuprinol-clear. The wood blocks were inoculated with two white rot fungi; Pleurotus squarrosullus and Lentinus subnudus for 12 weeks. Absorption of chemicals were determined at two concentration levels while resistance to decay was tested using Maximum Compressive Strength parallel to grain (MCS//). Data obtained were analyzed using ANOVA and descriptive statistics. Within wood blocks of the same species, absorption of both HWE and cuprinol-clear were not significantly different at both 4% and 8% concentrations. In both preservatives G.arborea test bocks produced higher MCS// than test blocks of T. scleroxylon. HWE was effective in reducing the impact of white rot in Gmelina arborea and Triplochiton scleroxylon.Keywords: Heartwood extract, Gmelina arborea, Triplochiton scleroxylon, White rot fungi, Compressive strength. 

VARIATION IN SOIL PHYSICO-CHEMICAL PROPERTIES IN THREE LAND USE TYPES OF OGUN RIVER WATERSHED

Conversion of watershed to other Land Use Types (LUTs) has implications on soil nutrients. Therefore, this study investigated the effects of three LUTs on soil physico-chemical properties of Ogun River watershed. The Ogun River watershed was stratified into Guinea Savannah (GS), Rainforest (RF) and Swamp Forest (SF) Ecological Zones (EZs). Three LUTs: Natural Forest (NF), Disturbed Forest (DF) and Farmland (FL) were purposively selected in GS: GSNF, GSDF, GSFL; RF: RFNF, RFDF, RFFL and SF: SFNF, SFDF, SFFL, respectively. Five out of sixteen plots laid along the transects lines were randomly selected in each of LUTs in the three ecological zones for soil sampling. In each of the selected plots, 5 soil samples were collected at the four corners and centre of the plot at two depths: 0-15 cm, 15-30 cm. Physico-chemical properties of soil samples were determined following standard procedures. Data were analysed using descriptive statistics and Analysis of variance (ANOVA) was used to test for differences in Physico-chemical variables of Ogun River soil samples using 3 x 3 x 2 factorial experiments. There were significant differences in Physico-chemical properties among land use types, Ecological zones and between soil depths of Ogun River watershed (P < 0.05). Soil Cation Exchange Capacity ranged from 2.37±0.01 (GSFL) to 8.50±0.04 (GSNF); Total Nitrogen increased from 0.88±0.01 (RFFL) to 4.79±0.05 (GSNF) while Soil Organic Matter ranged from 1.48±0.01 (GSFL) to 13.12±0.21 (GSNF).  It was found that continuous changes in land vegetative cover Ogun River watershed through human activities negatively affected soil physico-chemical properties. Therefore, other anthropogenic activities that will intercept nutrient cycling in the watershed ecosystem must be discouraged