ABSTRACT
The effect of gully erosion has affected inhabitants, causing some individuals to be homeless and others jobless. It has affected farmlands, settlements, roads, man and its animals, including wildlife. This study assesses the air quality and physico-chemical conditions of soils and water of Ogbe-Okwe gully in Ukwu-Nzu, Delta State of Nigeria.
The Ogbe-Okwe gully erosion is located in Aniocha North Local Government Area of Delta State. Samples (surface water, soil and air) were collected from gully erosion sites (March to October, 2017). Soil samples were collected in triplicates with the aid of Auger while water samples were collected with sterilized plastic containers. Air samples were collected using AeroQual Series 500 Air Sampler and analysed for SPM, NO2, SO2, H2S, O3, VOCs, CO and CH4. Surface water samples were collected with sterile 1 litre plastic containers from Iyocha stream close to the Ukwu Nzu community.
The mean values of air quality parameters analyzed are as follows:- Total Suspended Particulate (TSP) ranged from 15.43 - 28.55 µg/m3, Nitrogen dioxide (NO2) (0.00 ± 0.0 - 0.01 ± 0.0 µg/m3), Sulphur dioxide (SO2) (0.00 ± 0.0 - 0.27 ± 0.0 µg/m3), Hydrogen sulphide (H2S) (0.00 ± 0.0 - 0.00 ± 0.0 µg/m3), Ozone (O3) (0.00 ± 0.0 - 0.01 ± 0.0 µg/m3), Volatile Organic Compounds (VOCs) (0.010 ± 0.0 - 0.61 ± 0.0 µg/m3), Carbon monoxide (CO) (0.010 ± 0.0 - 0.01 ± 0.0 µg/m3) and Methane (CH4) (0.010 ± 0.0 - 0.01 ± 0.0 µg/m3). The range of the physicochemical characteristics of soils samples were as follows;- clay (24.00 ± 1.92 - 36.00 ± 2.96 %), silt (24.00 ± 1.92 - 33.00 ± 2.83 %), sand (33.00 ± 2.83 - 51.00 ± 3.89 %), pH (6.70 ± 0.50 - 7.88 ± 0.93), organic matter (0.91 ± 0.37 - 2.00 ± 1.00 %), organic carbon (0.51 ± 0.25 - 0.89 ± 0.37 %), and total nitrogen (0.01 ± 0.00 - 0.05 ± 0.00 %). Other physicochemical parameters are;- electrical conductivity (4.12 ± 1.45 - 4.81 ± 0.36 µS/cm), available phosphorus (150.00 ± 5.00 - 180.00 ± 5.74 mg/kg), total exchangeable bases (1.60 ± 0.42 - 1.99 ± 0.69 cmol/kg), calcium (1.20 ± 0.15 - 1.22 ± 0.17 mg/kg), magnesium (0.40 ± 0.00 - 0.51 ± 0.10 mg/kg), sodium (0.02 ± 0.00 - 0.05 ± 0.00 mg/kg) and potassium (0.04 ± 0.03 - 0.08 ± 0.00 mg/kg). Heavy metal results obtained from the gully erosion site show that cadmium values range from 0.16±0.13 - 0.30±0.13mg/kg, Lead (1.26 ± 0.33 - 3.50 ± 0.51mg/kg), Zinc (25.12 ± 2.82 - 79.02 ± 3.29 mg/kg), Copper (27.89 ± 2.49 - 63.08 ± 3.68 mg/kg), Iron (191.16 ± 5.07 - 212.16 ± 5.92 mg/kg) and Manganese (10.80 ± 0.49 - 18.00 ± 0.81 mg/kg). The results obtained from this study indicates the presence of pollutants at high levels. This was attributed to the intensive anthropogenic activities of Ukwu-Nzu erosion site. It is very necessary for government to enact very strict laws that would help minimize the adverse effect of these activities.
