GROUNDWATER CONTAMINATION: PERFORMANCE, EFFECTS,LIMITATIONS AND CONTROL

The decisive role of groundwater as a decentralized source of drinking water both in rural and urban settings cannot be underrated. It accounts for nearly 80 percent of the rural domestic water needs, and 50 percent of the urban water needs. The inevitable importance of groundwater to humankind has led to its over-exploitation which is now resulting to aquifer contamination. Although many cases of contaminated groundwater have occurred throughout the globe, few successful experiences in remediating the problems are identifiable at this time. Many countries are in the early process of identifying their potential groundwater contamination problems while others are seeking for its remedy. At present, many innovative technologies are being evaluated for their usefulness and swift responses to groundwater contamination control as the conventional extraction and treatment processes have often proven to be very expensive and slow with respect to remediating th

GROUNDWATER POLLUTION AND CONTROL: AN OVERVIEW

The pollutant creates a contaminant plume within an aquifer. Movement of water and dispersion within the aquifer spreads the pollutant over a wider area. This Chapter is aimed at reviewing the groundwater pollution sources, solid wastes and control measures for groundwater pollution. Pollution can occur from on-site sanitation systems, effluent from wastewater treatment plants, landfills, leaking sewers, petrol stations or from over application of fertilizers in agriculture. Pollution (or contamination) can also occur from naturally occurring contaminants, such as fluoride or arsenic. Using polluted groundwater causes hazards to public health through poisoning or the spread of disease. In spite of various awareness embarked upon by various government agencies and non-governmental agencies, some Nigerians still cultivate the habit of disposing wastes indiscriminately. Government agencies should be more funded, gear up to rise to the occasion by combating this seemingly intractable problem. Conclusively

Estimation of overburden thickness of industrial estate Ogbomoso, Southwestern Nigeria

Vertical Electrical Sounding (VES) geophysical method was used to delineate Oyo State Industrial Estate, Ogbomoso South Local Government Area, Southwestern Nigeria. The study area falls within latitude 080 06′ 07.4″ and 080 06′ 25.4″ and longitude 0040 15′ 03.3″ and 0040 15′ 49.0″. The research was conducted with a view to estimating the overburden thickness and to know the competent zones with respect to engineering purpose in the study area. Ten Vertical Electrical Soundings (VES) were carried out across the area using the schlumberger electrode array configuration with current electrode separation (AB) varying from 130m to 200m. Nine out of the ten modeled curves were H-type where the remaining one was KH-type. The geoelectric sections obtained from the sounding curves revealed 3-layer and 4-layer earth models respectively. The models showed the subsurface layers categorized into the topsoil/first layer, second layer, third layer (which only revealed beneath one VES station), and the last layer (which is either fractured basement or fresh bedrock). Areas with thick overburden and those with fractured basement are the areas that factories making use of heavy machines should not be built on it. This is because the continual vibration of the heavy machines might cause subsidence in the factories in the future which might lead to loss of life and properties

Geoelectric assessment of groundwater prospect and vulnerability of overburden aquifers at Adumasun Area, Oniye, Southwestern Nigeria

Adumasun lies on a Precambrian basement complex of Southwestern Nigeria. Some kilometers away from the study area especially at Igangan is characterized by outcrops of crystalline basement rocks. Inadequate municipal water supply from State Water Corporation, coupled with hydrogeologically difficult nature of the terrain, individuals and corporate bodies indiscriminately sink tube wells and boreholes within the unconsolidated overburden materials, with glaring lack of concerns for the vulnerability status of aquifers, and possible environmental risk. Vertical Electrical Sounding method was used to map Adumasun area, Oniye, Oyo State with a view to assessing the groundwater prospect, focused on the thickness of the unconsolidated materials overlying the crystalline bedrock. The resistivity parameters of the geoelectric topmost layer across the area were also used to assess the vulnerability of the underlying aquifers to near-surface contaminants. The thickness of the unconsolidated overburden varies from 3.1m to 20.1m, where about 60% falls within the 10m-14.9m brackets. This shows that unconsolidated materials are not thick and hence averagely low groundwater prospect. 80% of the topmost geoelectric layer in the study area has resistivity mostly within the range of 1-100Wm. Resistivity values within these brackets tend to indicate silt or clay sequence, which can constitute effective protective geologic barriers for the underlying aquifers. This suggests that aquifers within the unconsolidated overburden at Adumasun are mostly capped by impervious/semi-pervious materials, geologically protecting the underlying aquifers from near-surface contaminants

Groundmagnetic survey to investigate on the fault pattern of industrial estate Ogbomoso, Southwestern Nigeria

Groundmagnetic method was used to investigate on the fault pattern of industrial estate Ogbomoso which falls within latitude 080 06′ 07.4″ and 080 06′ 25.4″ and longitude 0040 15′ 03.3″ and 0040 15′ 49.0″ Southwestern Nigeria, with a view to determining the competency of the basement. This is to know whether the basement will be competent enough to withstand the construction of the factories in the study area or not. A total of four traverses were established for the purpose of the groundmagnetic study, and the results were presented as groundmagnetic profiles of varying magnetic intensities. Result from first vertical derivative revealed that the intensities and characteristics nature of the magnetic anomalies as expressed by all profiles are indicative of the different rock types producing them. Qualitative and quantitative interpretation of individual magnetic anomaly and geological knowledge of the survey area yielded information on the depth of geological features (e.g. rock contact, faults or fractures), structures and magnetic properties of rock units. From the preliminary interpretation, the existence of some structural features such as a likely fault and relatively mineralized zones that might contain magnetic minerals of essential magnetite origin is revealed. It was also revealed that industrial estate Ogbomoso is averagely competent for engineering purpos

SEISMICITY ANOMALIES OF M 5.0+ EARTHQUAKES IN CHILE DURING 1964-2015

The study of magnitude-frequency distribution of earthquake hazards in a region remains a crucial analysis in seismology. Its significance has varied from seismicity quantification to earthquake prediction. The analysis of seismicity anomalies of magnitude M => 5.0 earthquakes in Chile from 1964 to 2015 was undertaken by the present study with a view of reporting the trend of earthquake occurrences in the region. Chile has an area of about 756, 950 km2 with an extensive coastline of approximately 6,435 kms. It is situated in a highly seismically and volcanically active zone with a long, narrow strip of land between the Andes Mountains to the east and the Pacific Ocean to the west.It borders Peru to the north, Bolivia to the northeast, Argentina to the east and the Drake Passage in the far south. Of a total of 3,893 earthquakes that have been documented historically, magnitudes Richter 5.0 to 5.9 represent 92.6%, magnitudes 6.0 to 6.9 represent 6.8%, magnitudes 7.0 to 7.9 represent 0.6%, and magnitudes 8.0 to 8.9 about 0.1%. The quantity of earthquakes (a-value) revealed an estimate of 8.4. The b-value was estimated using Gutenberg-Richter (GR) and the Maximum Likelihood Estimation (MLE) methods. The estimated b-value using GR and MLE methods are 0.97 and 1.1 respectively, with an estimated average b-value ≈ 1. The present studies supprort the conclusion that Chile is seismically very active and prone to the recurrence of moderateto-great earthquakes in the future

AN OVERVIEW OF MAGNETIC METHOD IN MINERAL EXPLORATION

In modern times, the economic strength of a nation, the standard of living and independence of her citizens depend on the nation's industrial strength and her economic buoyancy. These two parameters, that is, the nation's industrial strength and the buoyancy of the industries in each country, sometimes form the bases for classifying the countries as "developed" (e.g., America and Japan) or "developing" (e.g., Nigeria and Ghana) with every nation striving to achieve the former status. The availability of the raw materials needed by most industries is one of the primary factors for the establishment of the industries. The raw material needs of most industries occur sporadically in one form or the other inside the earth's crust and the search for them as been one of man's major concerns. This paper gives the literature report about the use of magnetic method in mineral exploration. Magnetic exploration also referred to as “potential field” exploration is used to give geoscientist an indirect way to “see” beneath the Earth’s surface by sensing physical properties of rocks (magnetization). Magnetic method exploration can help locate minerals. Potential field survey is relatively inexpensive and can quickly cover large areas of ground. The method is relatively cheap, non-invasive and non-destructive environmentally speaking

Heavy metals' data in soils for agricultural activities

In this article, the heavy metals in soils for agricultural activities were analyzed statistically. Ten(10)soil samples were randomly taken across the agricultural zones in Odo-Oba, southwestern Nigeria. Ten(10)metals; namely : copper(Cu), lead(Pb),chromium(Cr), arsenic(As), zinc(Zn), cadmium(Cd),nickel(Ni),antimony(Sb), cobalt(Co) and vanadium(V) were determined and compared with the guideline values.When the values were compared with the international standard,none of the heavy metals in the study area exceeded the threshold limit.However,the maximum range of the samples showed that Cr and V exceeded the permissible limit which could be associated with ecological risk.The data can reveal the distributions of heavy metals in the agricultural top soil of Odo-Oba, and can be used to estimate the risks associated with the consumption of crops grown on such soils

Groundwater Prospect in a Typical Precambrian Basement Complex using Karous-Hjelt and Fraser Filtering Techniques

Electromagnetic survey was carried out at Ibodi, village, Ilesa in Atakunmosa West Local government area with a view to determining the probable locations for groundwater exploration in the study area. Ibodi falls within latitude 70 35′ 35.21″ North and longitude 40 40′ 48.28″ East. The development and increase in immigrants at Ibodi has necessitated this study. A total of five profiles from North to South directions were occupied. It was discovered that distances (100.0-140.0) m, 40.0 m, 80.0 m and 35.0 m on profiles 1, 3, 4 and 5 respectively revealed fractured zones which are suspected to be the best locations for groundwater prospects in the study area