Assessment of organophosphate pesticide residues in environmental media of Araromi farm settlement, Osun State, Nigeria

The aim of the study was to assess the occurrence and distribution of organophosphate compounds residue in soil, surface water, sediment, and banana crops in Araromi farm settlement, Osun State, Nigeria. Organophosphate pesticide residues were determined using a gas chromatography equipped with Flame-Ionization Detection (GC-FID) in 16 soil samples from cocoa and banana farms, 6 water and sediment samples each, and 8 banana samples from 4 farms in the study site. Fourteen organophosphate compounds were detected (acephate, omethoate, dementon-s-methyl, dimethoate, tolcofos-methyl, pirimiphos-methyl, malathion, chlorpyrifos, methidathion, prothiofos, profenofos, ethion, azinphos-methyl and pyrazophos). Tolclofos-methyl, pirimiphos-methyl and prothiofos were detected in all the soil and sediment samples with concentration ranges of 1.9-12.9, 2.25-6.98 and 3.38-9.89 mg/kg respectively in soil and 8.13-9.83, 2.82-25.1 and 3.70-19.5 mg/kg respectively in sediment. Dimethoate, pirimiphos-methyl and prothiofos with concentration ranges, 0.06-0.28, 0.09-0.18 and 0.16-6.11 mg/L respectively were mostly detected in water samples while dimethoate, tolcofos-methyl, malathion, methidathion, prothiofos, ethion and azinphos-methyl compounds were detected in all the banana samples with concentration ranges, 3.40-12.0, 1.82-6.26, 5.73-9.48, 29.7-145, 8.24-20.1, 3.87-9.35 and 3.66-12.2 mg/kg respectively. The organophosphate mean residue concentrations were mostly significantly higher than the Maximum Residue Limits (MRL) at p<0.05. Across the three samples, only pirimiphos-methyl was significantly higher in water samples, omethoate in sediment; acephate, dementon-s-methyl and chlorpyrifos in banana were also not significantly higher at p<0.05. A strong positive significant correlation was observed between the organophosphate compounds in the banana and water samples (R=0.77, p=0.002) at p<0.05. The occurrence of organophosphate compounds in concentrations above MRLs may pose serious environmental and health risks.

Burial practice and its effect on groundwater pollution in Maiduguri, Nigeria

Cemeteries in Nigeria have never been perceived as having a significant potential contamination to the environment and are often located within residential setups. This work presents a study of special interest, because up till now, there are no known publications in the north-eastern states of Nigeria that investigated the relationship between cemeteries and the natural environment. The objective was to investigate whether burial practices affect the groundwater within the vicinity of an active municipal cemetery in the Gwange area of the Maiduguri metropolis, Borno State, Nigeria. Groundwater quality measurement from boreholes located at varying radial distances from the cemetery was also conducted. The result was compared with that of WHO and showed evidence of attenuation with distance. The method of burial is a chemical-free method and dictated by local culture in the area. The site is underlain by a sedimentary rock of the Chad Formation and is characterized by coarse-grained soils of high permeability coefficient (1.04 × 10^-4-2.38 × 10^-4 cm/s). The soil sample was composed of 3.2 to 8.4% fines which fall beneath the standard of 30% that is considered adequate for natural attenuation of contaminants. The soils were poorly graded and exhibit non-plastic properties. The grave invert, being predominantly higher than 1 m, seems to have significantly influenced the low levels or the absence of contaminants especially cations in the groundwater sample. The high levels of pH (9.5), EC (1874 μs/cm), NO₃ (67.4 mg/l), NO₂ (0.92 mg/l), PO₄ (344.5 mg/l), and NH₄ (1.03 mg/l) in groundwater samples (especially the cemetery borehole) are an indication that higher interment density over time presents a significant threat to groundwater quality.

Anthropogenic activities impact on atmospheric environmental quality in a gas-flaring community: application of fuzzy logic modelling concept

We present a modelling concept for evaluating the impacts of anthropogenic activities suspected to be from gas flaring on the quality of the atmosphere using domestic roof-harvested rainwater (DRHRW) as indicator. We analysed seven metals (Cu, Cd, Pb, Zn, Fe, Ca, and Mg) and six water quality parameters (acidity, PO₄^3-, SO₄^2-, NO₃^-_, Cl^-, and pH). These were used as input parameters in 12 sampling points from gas-flaring environments (Port Harcourt, Nigeria) using Ibadan as reference. We formulated the results of these input parameters into membership function fuzzy matrices based on four degrees of impact: extremely high, high, medium, and low, using regulatory limits as criteria. We generated indices that classified the degree of anthropogenic activity impact on the sites from the product membership function matrices and weight matrices, with investigated (gas-flaring) environment as between medium and high impact compared to those from reference (residential) environment that was classified as between low and medium impact. Major contaminants of concern found in the harvested rainwater were Pb and Cd. There is also the urgent need to stop gas-flaring activities in Port Harcourt area in particular and Niger Delta region of Nigeria in general, so as to minimise the untold health hazard that people living in the area are currently faced with. The fuzzy methodology presented has also indicated that the water cannot safely support potable uses and should not be consumed without purification due to the impact of anthropogenic activities in the area but may be useful for other domestic purposes.

Fuzzy Logic Modelling of the Effects of Pollution on Domestic Roof-Harvested Rainwater Quality in Residential and Industrial Environments

This study presents the effects of environmental pollution on the quality of domestic roof-harvested rainwater (DRHRW) using fuzzy comprehensive assessment (FCA). Seven metals (Cu, Cd, Pb, Zn, Fe, Ca, and Mg) and six water-quality parameters (Acidity, PO4 (3-), SO4 (2-), NO3 (-) , Cl(-), and pH) were investigated in DRHRW sampled from 12 sampling points each from Ibadan (residential) and Lagos (industrial) environments, Nigeria. The results of these parameters were formulated into membership function fuzzy matrices based on four contamination classifications of high, marginal, low, and poor qualities using regulatory limits as criteria. The products membership function matrices and weight matrices generated indices that classified the degree of anthropogenic activity impact on the sites. Results of FCA classified the DRHRW from residential environment as between high and marginal quality, whereas DRHRW from industrial environment is classified between marginal and low quality. Lead and Cd were major contaminants of concern found in these harvested water.