Assessment of environmental degradation of soil and groundwater: A case study of waste disposal in Benin West Moat - Ekenwan gully Benin City, Edo State, Nigeria

The ancient Benin moat of 2.00 to 5.00 m width, and 10 to 30 m depth almost concentrically dug round the City, is supposed to be an important socio-cultural artifact if well preserved. It has served its good purpose of defense and protection of the ancient Bini civilization. Now, modern urbanization pressure has defaced and is degrading the moat and its environs through house development, soil quarrying, gullying, flood catchment, and waste disposal. Because of its extent, it is pertinent to understand its pedo-geological and hydrogeological setting in order to assess the impact of the waste disposal on the soil and groundwater systems. Random; 11 soil (pool) samples at 0.0 to 0.5 m depth, and eight groundwater samples from pumping boreholes, 0.5 to 10.0 m on both sides of the moat were drawn. Samples were analyzed for their chemical, heavy metal constituents (including microbial in water). Comparisons of means with pristine locations in previous studies were conducted using one way analysis of variance (ANOVA) at 5% α level of significance. Results reveal contamination of soil with Al, Cd, Fe, Pb and THC at P<0.05. The groundwater also is polluted with presumptive coliform of 1.0 x 102 to 1.5 x 103 cfu/ml-1 and heavy metals; Al, Cd, and Pb at P<0.01 indicating high significant difference. This indicates that the once protective moat is now a likely area of phytotoxicity and general environmental toxicity to man if chronic exposure is allowed by continual waste disposal.Key words: Wastes disposal soil and groundwater contamination in Benin West-Moat, case of environmental toxicity

Characterization of Soil and Sediment Parameters of Jisike-Izombe Upper Aquifer System for Assessment of the Potential of Groundwater Pollution

The JES field, an onshore field in the Jisike – Izombe area of southeastern Nigeria had a number of oil-producing wells before it was abandoned over a decade ago. By means of soil/sediment samples retrieved from three strategically located boreholes around the field, the subsurface units were delineated and the physical characteristics of the vadose zone were determined in order to predict the groundwater pollution potential of the upper aquifer system in the area. Ground conditions were found to be approximately 1metre (3.043ft) of loamy top soil overlying about 1.2metres (3.65ft) of clayey laterite which overlies 19.4 – 24.6metres i.e (60ft – 75ft) of reddish-brown silty sand, beneath which is medium – coarse grained white sand which constitutes the aquifer system with estimated hydraulic conductivity in the range 1 x 10-1 to 169 x 10-1 mm/sec. Flow analysis of groundwater indicates a southwesterly flow with the River Niger as possible discharge zone. The high leaching potentials and high transmissive properties of the sediments below the clayey laterite suggests a vulnerability of the aquifer to pollution through vertical infiltration. However, borehole water quality parameters for the area show that groundwater quality is not in anyway compromised when compared to the WHO limits. Rather, it is argued that the groundwater is naturally well protected by the upper part of the vadose zone where the clayey lateritic soil with iron oxide cementation of soil particles provides an appreciable degree of barrier to downward movement of contaminants. Because of the clayey behavour of the near-surface soils and their affinity for the retention of contaminants, it is concluded that the area is not a locus of groundwater pollution. © JASE

The Quality of Groundwater in Benin City: A baseline study on inorganic chemicals and microbial contaminants of health importance in boreholes and open wells.

Purpose: Inorganic chemicals and microorganisms are common in human environments and at high levels poisoning from the chronic effects have occasionally occurred. The purpose of this study was therefore to investigate whether the levels of inorganic chemicals and microbial contaminants in boreholes and open wells in selected Districts in Benin City are sufficient to affect the health of the inhabitants of the areas under investigation. Method: Six (6) boreholes and three (3) open wells were randomly selected from two Districts (Okhoro and Teboga) in Benin City. Water samples were collected from the boreholes and open wells using standard techniques. Lead (Pb), chromium (Cr), zinc (Zn), and cadmium (Cd) concentrations as well as aerobic bacteria, presumptive faecal coliform, E. coli, faecal Streptococci and fungi in the water samples were determined using standard procedures. World Health Organisation acceptable limits for drinking water were used in the evaluation. Result: All the boreholes and open wells were contaminated with abnormal levels of Pb. High levels of Cr and Cd were found in the borehole and open wells at Okhoro. Abnormal levels of Zn concentrations were detected in almost all the boreholes and open wells. All the boreholes at Teboga were contaminated with unacceptable levels of aerobic bacteria and fungi. Presumptive faecal colifom, E.coli and faecal Streptococci were seen in all the boreholes. Conclusion: Some boreholes and open wells in Okhoro and Teboga Districts in Benin City are contaminated with abnormal levels of metals and microorganisms capable of causing health hazards to the consumers of boreholes and open wells. Keywords: Benin City, boreholes, inorganic chemicals, microorganisms, open wells. Tropical Journal of Pharmaceutical Research 2002; 1(2):75-8

Geophysical Investigation of Ground-Water in Agbor Area of Delta State, Nigeria

Geophysical survey was curried out in order to investigate Groundwater existence in Agbor Area of Delta State Nigeria. This research work became necessary in order to solve the acute water shortage in the area by way of prospecting or searching for additional aquifer which would subsidize the existing one, domestically, industrially and agriculturally. Ten(10) vertical electrical sounding (VES) (uniformly distributed) was conducted in Agbor area and its environs using schlumberger electrode array. The VES were carried out with semi electrode spacing in the range Im-928m at six (06) points per decade. The results of the interpretation identified wet sand/clean sand as perched aquifer which can produce ground water to the bore-hole at a perceptible rate between depth of 90m to 140m as confirmed by a nearby driller logs of Agbor [21]. The resistivity of the aquifer detected varied from 102.4 ohm-m to 100,000 ohm-m while the thickness ranges from 31.9m to 103.7m

Geophysical Exploration of Gravel Deposits in Abudu Area of Edo State, Nigeria

The need to prospect for gravel deposit in Abudu area of Edo State, Nigeria became inevitable in view of the fact that it has greatly aided many developed and developing nations of the world commercially. The geophysical study was carried out using vertical electrical sounding (VES) of electrical resistivity method, employing Schumberger configuration techniques based on six (06) points per decade operation to justify the study of assembling resistivity data. Ten (10) fairly distributed VES in eight (08) different stations of Abudu Area was carried out to investigate the subsurface Lithologies or rock types. So as to detect gravel deposits. The software or package IP12WIN utilizing computer iteration was used for interpretation of apparent resistivity data. The result of the geophysical survey showed that gravel deposit was intercepted at a depth varying from about 25.0m to 140.0m below sea level while its thicknesses varied from about 2.0m to 120.0m. The resistivity of the detected gravel deposit varied from about 1000 0hm-m to 7000 0hm-m. Area of probable gravel deposits formations and their thicknesses have been identified especially for commercial purposes.Journal of the Nigerian Association of Mathematical Physics, Volume 19 (November, 2011), pp 513 – 51

Geophysical Study of Aquifer Properties at Isihor Village of Edo State, Nigeria

The primary objective of this research work, is to reduce youth restiveness in the area to its lowest ebb by setting up additional pure water industry or factory where these youths will be gainfully employed and hence the need to prospect or search for additional aquifer or water bearing formations became inevitable. Ten (10) vertical electrical sounding (VES) (uniformly distributed) based on electrical resistivity method was carried out in a geophysical survey in order to study aquifer properties. These properties include depth, thickness and nature of soil above the aquifer. Schlumberger array of VES was conducted in Isihor Village and its environs area of Edo state, Nigeria. The resistivity soundings were carried out with semi current electrode spacing in the range 1-632m using six (06) points per decade to determine the depth, thickness of the recommended  aquifer. The geophysical results were used to determine the depth,  thickness of the recommended aquifer or water bearing formation and the thickness of the sandy soil above it. The resistivities of the detected aquifer varied from 800 ohm-m to 9000 ohm-m while its depths varied from 15m to 120.0m. The thickness of the detected aquifer which varied from 10m to 60m enable us to known the probable area for future drilling operation

Geophysical determination of buried structural features at Ovbiogie village, Edo State, Nigeria.

The result of this paper is to determine geophysically buried structuralfeatures using Schlumberger array of vertical electrical sounding. The need to detect riversand/gravel as perched aquifer for clean water production became necessary because of limited resources of pure water in the study area. The research work was done at Ovbiogie village in Ovia North East Local Government Area of Edo State. The vertical electrical resistivity soundings were carried out with maximum current electrode spacing of 928m using six points per decade. Computer iterated data from the study area made the structural determination possible with resistivity values ranging from 85ohm-m to 735ohm-m and depth varying from 1m to 40m. The results obtained obviously showed the existence of the following structural features; clayey soil at a depth of 1.0m, sandy soil at a depth of 3.0m, clay and mart at a depth of 12.6m, river sand and gravel at a depth of 35.1m and basalt at a depth of infinity