HYDROGEOCHEMISTRY AND ENGINEERING GEOLOGY OF ADETA AREA, ILORIN, NORTH-CENTRAL NIGERIA
A study on hydrogeochemistry and quality of shallow water and engineering properties of soil around Adeta area in Ilorin was carried out based on data obtained from the field and laboratory. Groundwater flow, descriptive, and multivariant statistical analyses, piper, stiff and durov diagrams, as well water quality indices were used to describe hydrochemistry and water quality suitability of the area. Grain-size distribution, Atterberg limit and permeability indices were used to determine the soil properties. The results showed that groundwater flow is in NE-SW direction. The cations occur in order of abundance of Ca>Na>K>Mg and anions are in the order of Cl>SO4>NO3>HCO3. The hydrogeochemical trends showed that the water type in the area is Na+K –SO4+Cl from both piper and durov diagrams. The stiff diagram indicates three water type group; Na-Cl, Ca-CO3 and Mg-SO4. The grain size analysis showed that sample S1 have 5.4% clay, 5.0 % Silt, 30 % Fine sand 36.3 % Coarse sand and 20,8% Gravel with CU of 1.33 and CC of 0.4; sample S2 has 0.1% clay, 0,7% silt, 41.2% fine sand, 48.3 % Coarse sand and 6.9 % fine gravel with CU of 5.3 and CC 2.5; sample S3 have 1.1% clay, 0.8% silt, 40.2% fine sand, 51.5% coarse sand and 6.5% fine gravel, with CU of 4.67 and CC 1.7.Samples S2 and S3 can be classified as coarse SAND; samples S1 can be classified as slightly gravelly SAND, based on USC table of soil distribution. Therefore, based on the above classification, all the soil samples are poorly graded. The result of the permeability shows that sample S1 have coefficient of permeability of 7.7x10-4mm/s, S2 has 1.9x10-4mm/s, S3 and 8.0x10-5mm/s. Sample S1, S2, and S3, have liquid limit of 30, 30 and 35 respectively and plastic values of 31.3, 28.3 and 33.3 respectively with plasticity index of -1, 3, 1.7 and 1.7 respectively.Consistency test based on liquid limit and plastic limit values of an average of 31.7 and 30.97 with plastic index of 1.7indicating a medium plasticity state. The low LI and PI values are an indication of no changes in pore fluid characteristics of soil.The shallow water is contamination with Mn andthe soil for the areahas poor permeability to promote migration of the Mn.
TABLE OF CONTENTS
Title Page........................................................................................... i
Table of contents................................................................................. v
List of Tables...................................................................................... vi
List of Figures...................................................................................... vii
List of Plates………………………………………………………..... viii
1.1 General Statement
1.2 Aim and Objectives
1.3 Scope of the Study
1.4 The Study Area
1.4.1 Location and Extent of the Study Area
1.4.2 Climate and Vegetation
1.5 Water Quality and Principles of Hydrogeochemstry
1.6 Engineering Geology of soil
1.7 Literature Review
2.1 Geology of Nigeria
2.2 Geology of the Study Area
2.3 Hydrogeology of the Area
2.4 Hydrogeochemistry of the Area
3.1 Materials Use while in the Field
3.2 Desk Work
3.3 Reconnaissance Survey
3.4 Field Work
3.4.1 Hydrogeological Mapping
3.6 Laboratory Analysis
3.6.1 ICP-MS and AAS
3.6.1 Grain Size Distribution
3.6.2 Atterberg’s Consistency Limits
3.4.3 Permeability Test
4.0 Result and Discussions
4.1 Flow Direction
4.2.1 Major Ions in Water
188.8.131.52 Statistical Distributions
184.108.40.206 Plots and Ratios
4.2.3 Heavy metals
220.127.116.11 Statistical Distribution
18.104.22.168 Water Quality Index Calculation
4.3 Geotechnical Survey Results
4.3.2 Result and Discussion of Grain Size Analysis
4.3.3 Result and Discussion of Atterberg’s Limit
4.3.4 Result and Discussion of Permeability Test
5.0 Conclusion and Recommendation
5.1.1 Groundwater flow
5.1.2 Hydrochemistry and Water Quality
5.1.3 Engineering Properties of Soils
1.1 GENERAL STATEMENT
Increase in population and rapid expansion of cities has resulted to generation of huge waste and the manner these wastes are disposed constitutes serious health and environmental problems.Interactions between water and host rock influenced groundwater hydrochemistry and determine its suitabilityfor most purpose. The variations in groundwater chemistry is controlled by these major geochemical processes, Weathering reaction, Ion exchange, dissolution, redox, etc.(Mathes, 1982; Kumar et al., 2006), because as groundwater flows, its chemistry will evolve, as it interacts with aquifer minerals or internal mixing among different groundwater (Domenico, 1972). So, hydrochemical processes help to get an insight into the contributions of rock-water interaction and anthropogenic influences. Soil and groundwater acidification and nitrification have been linked to waste dumps (Bacud et al., 1994) as well as microbial contamination of soil and groundwater system (Awomeso et al., 2010). Sia Su (2008) attributed cancer,heart diseases and teratogenic abnormalities to groundwater contamination via leachate from waste dumps. In Engineering geology, soil is vital to any construction and forms a larger portion of the construction materials and basically forms the foundation for their structure. Such geotechnical test enable technical evaluation of the suitability of soil to support a design structure, such geotechnical test include: gain size analysis, Atterberg limits, permeability test, moisture content, consolidation, compaction and mineral composition analysis etc.Ilorin, as in most cities in Nigeria lack modern landfill facilities, all depend on open dumpsite that lack sorting and recycling mechanisms. This poor management will create number of adverse environmental challenges, such as pollution of underground soil bed and/or aquifer (Albores et al.,2007; Okoronkwo et al.,2006). In the past, studies on groundwater exploitation, geotechnical, environmental geology and contamination status in the part of Ilorin include, Olasehinde 1999; Sulyman, 2007, Ige and Ogunsanwo 2009; Ojulari et al.,2014; Owolabi et al., 2016. Ige and Ogunsanwo, 2009evaluate the effects of leachate from open landfill in the Ita-Amo area of Ilorin, southwestern Nigeria. Proper understanding of the properties of the soils around dumpsite will throw light on the activities of the leachates in relation to the contamination of the groundwater. Hence this research work involves investigation of water chemistry of shallow aquifer and preliminary soil investigation around Adeta in Ilorin-West Local Government Area of Kwara State, North-Central Nigeria.
1.2 AIM AND OBJECTIVES
The aim of this project is to study the impact of open waste dump on the subsurface and the objectives are:
⦁ To describe Hydrogeochemistry of shallow water
⦁ To investigate heavy metals concentration in shallow water
⦁ To evaluate the influence of geotechnical properties of the soils around selected wells study area.
⦁ To examine the effect of wasteon underground water
1.3 SCOPE OF THE STUDY
The Scope of this project is based entirely on field sampling,hydrogeological inventory and geotechnical laboratory analyses of the soils. To achieve this goal, soil samples were collected and some identification tests such as, grain size analysis, Atterberg’s consistency limit, permeability test, thin section and mineral composition test etc. were conducted.
1.4 THE STUDY AREA
1.4.1 Location and extent of the study area
The study area lies between the latitude 80 29'N and 80 30'N and longitude 40 31'E and 40 33'E, covering these settlements Adeta, in Ilorin-West Local Government Area of Kwara State, Nigeria. The location is built-up area. The area can be accessed through Adeta roundabout from Al-Hikmah University
Figure 1.1: Topographic map of the study area.
1.4.2 Climate and vegetation
The vegetation of the area is savannah grassland with scattered trees and shrubs being at the fringe of the middle belt of Nigeria. The prevailing climatic condition in the area is wet (rainy) and dry seasons. The wet (rainy) season begins in early April and ends in October while the dry season starts in November and last till March. The mean annual rainfall is about 1200 mm with an average daily temperature of 26 ℃ (Parsons, 1970).
1.5 WATER QUALITY AND HYDROGEOCHEMSTRY
1.5.1 Water Quality
Water quality concept is a bit complex because of the factors that influence it. The quality of water depends on geological environment, natural movement, recovery and utilization. The quality of water is based on chemical and physical variables that are related to the intended use and for each variable the standard must be well define.
According to WHO (1996), water quality is aterm used to express the suitability of water to sustain various uses or processes. The established standard will guide to know whether water is acceptable or unacceptable for use. The quality of water is one of the factors controlling state of health of plants, animals and man. If the water fails to meet the set or acceptable standards, it must be treated before use (Cordobal et al., 2010).
2.4.1 Factors That Affect Water Quality
Water is life and therefore it plays a pivotal role to our health, food security, well-being, social and economic development of any society. Water quality is affected mostly by a wide range of natural and human influences. The most important of the natural influences are geological, hydrological, topographical, meteorological and climatic. Human influence on water quality arevaried in the degree, agricultural (application of pesticides, organic and inorganic fertilizer), industrial (effluent discharge and atmospheric pollution), forestry and mining activities. These factors significantly affect chemistry of both surface and underground water. Contamination of water with light and heavy metals are mainly determined by natural weathering, erosion of bed rocks and ore deposits and anthropogenic processes (Ettler et al., 2011; García-Lorenzo et al., 2011; Muhammad et al., 2011; Sracek et al., 2011). These processes degrade water quality and impair their use for drinking, domestic, agricultural and industrial purposes (Krishna et al., 2009).
1.5.2 Heavy metals and Sources of Heavy Metals
Heavy metals sources are numerous, the major ones are anthropogenic and geogenic sources. Anthropogenic sources: Heavy metals contamination can be divided into the following groups;
(i) Atmosphere to soil and water pathways
According to Dinis and Fiuza (2011) atmospheric emissions are probably the most preoccupants to human health and to environment due to either the great quantity involved or their wide spread dispersion. Cadmium, mercury and lead among other heavy metals have the ability to travel long distances in the atmosphere before deposition. They travel into the atmosphere to form of aerosol and later deposited via precipitation and sedimentation. Lin (1988) reported how lead pollution mainly from urban industrial copper plant, sulfuric acid plant, paint factory and large amount of waste from mining and chemical industries evolved into the atmosphere in a down town central Sweden. Also in Russia, Meshalkina (1996) reported how the environment was contaminated as a result of discharge of S, V, and As from factory Chimneys. Research conducted by Falahiardakani (1984) shows that transport, especially automotive transport causes serious heavy metal contamination of the atmosphere.
(ii) Solid waste pathways
Solid waste from mining activities and industries contaminates both water and soil seriously. According to Wuana & Okieimen (2011) the composition and processing of ore will determine the nature of pollutant. Large amounts of mine tailings discharged into the environment causes ecological problems and contaminate human water supplies. Heavy metals seep into the ground water during mining operations, washed away by rain water and collected in the lakes and aquifer. Contamination of this nature have been reported in different parts of the world, in Russia (Bustueva et al., 1994), USA (Hwang et al.,1997), Mexico (Benin et al., 1999), Chile (Rivara et al., 1997), Philippines (Applleton et al., 1999) , Zibabwe (Van Straaten, 2000; Yabe et al., 2015), Tanzania (Bitala et al.,2009), India (Reza and Singh, 2010), China (Liang et al., 2011) South Africa (Makiess et al., 2013), Iran (Ghazban et al., 2015) Thailand (Intamat et al., 2016).
Heavy metals move easily due to facilitation of sunlight, raining and washing when they are in the process of being govern and they spread to the surrounding water and soils at the shape of funnel and radiation (Gebreyesus, 2014). The increase in technology brings about industrial development coupled with acceleration of urban environmental and sewage treatment, by which sludge production will be on high. Generally, Cr, Pb, Cu, Zn and As in sludge will exceed control standard easily (Ding, 2000). Contamination of solid waste can be expanded easily with the aid of water and wind.
(iii) Agricultural chemical to soil and water pathways
Long term excessive application of fertilizer, pesticides and insecticides has resulted to heavy metal contamination of soil and water. According to Arao et al., (2010), the vast majority of pesticides are organic compounds, and a few inorganic compound or pure minerals, and some pesticides contain Hg, As, Cu, Zn and other heavy metals.
Raw sewage contains significant concentration of heavy metals which are not degraded by process of sewage treatment. Waste water from sanitary sewage, chemical waste water, and urban mining sewage has resulted to accumulation of heavy metals in soil and water bodies.
Heavy metal concentration occurs naturally in soil and water. Geological history always influences the mineralogy and geochemistry of soil and the presence of geochemical heavy metals in soil have been recently acknowledged as a significant source of soil and water contamination (Rodriguez and Reuter 2007, Morrison et al., 2009). In water, heavy metal concentration is always based on the type host rock but it rises to higher levels due to the release of heavy metals from contaminated soil, leachate and sediment. Heavy metals percolate into ground and surface water during run off and as the metallic pollutant move through the water, reaction occur with other elements and adhere to soil surface. For instance, aquifers polluted with arsenic have been reported in several countries including India, Argentina, Chile, Mexico, Bangladesh and Mexico (United Nations, 2001). High levels of fluoride in groundwater are also reported by Diaz- Barriga et al., (1997) in Mexico, Choubisa (2001) in India and Okunlola et al., (2016) in Nigeria.
pH always determine mobilization of heavy metals depending on the soil types, oxidation state of heavy metal, ion exchange capacity and physicochemical characteristics of soil, sediment and heavy metals (Evans, 1989).
2.3.3 Behavior and mobility of Heavy Metals
Behavior of heavy metal is controlled by various processes including metal cation released from contamination source materials such as mining, fertilizer, sludge, smelter dust, and slag. Behavior of heavy metals in soil is solely controlled by their sorption and desorption reaction with different soil constituents especially clay component (Appel and Ma, 2002).
1.6 ENGINEERING GEOLOGY OF SOIL
It involves the application of science of geology to structural designs. Geotechnical engineering practice being quite vast, only a brief list of the various applications is presented below
Soil mechanics are the name indicates deals with the mechanics of soils. It as develop as a branch of mechanics involving the application of both mechanics of soil and mechanics of fluids to problem involving soils. Of late due attention is being paid to the particle nature of soil medium, while studying its behavior Soil classification is to arrange various types of soils into specific grouos based on physical properties and engineering behavior of soils, with the purpose of finding the suitability of soils for different engineering applications lie construction of earth dams, highways and building foundations.
Olasehinde, 1989 preliminary results of hydrochemical Analysis of selected sites from Ilorin indicated no high concentrations of chemical components in most sites tested. The study used descriptive statistics and chemical plots (Piper and Stiff) to characterize the groundwater.
Vrbka et al., 1999Characterized rain, groundwater and surface water in area of Ilorin for water samples collected from 1997 rainy seasons, surface and subsurface sources (hand pumps, and dug wells). The piper diagram plot was used to characterize the waters. The temperature ranges in 240C to 310C, with slightly acidic. In the anion triangle of the plot, most plotted within the bicarbonate side and calcium in the cation. The abundance of occurrence of cation is in the order Ca>Na>K and CO3>Cl.
Kana et al., 2014 studies the suitability of groundwater for domestic and other uses in Nasarawa Town and Environs for forty (40) groundwater and Twenty (20) surface water. Descriptive statistics, piper diagram, gibbs plot and Sodium Absorption Ration were used to characterise the water. The water type is Ca-(Mg)-HCO3 based on piper and schoeller diagram. Groundwater showed to be suitable for drinking and irrigation purposes.
Liang et al., 2011, studied concentration and distribution pattern of Pb, Hg, Zn, Cu, Cr, As and Cd in surface water of Linglong gold mining area in China. Plasma mass spectrometry and AAS was used for the analysis of these metals and the result shows that surface water is seriously polluted by Hg, Zn and Cd and moderately polluted by Cr and As according to China national standard for surface water quality. Concentration of these metals was found to be decreasing along the flow direction farther away from the source of the pollution. Elemental content in the surface water are obviously influenced by geochemical properties and the sources of heavy metals.
ICPOES analytical technique was used by Gunnar et al.,(2012) for hydrogeochemical analysis of water on the contamination of water resources in part of Tarkwa mining area in Ghana. 17 out of 40 ground water show metal concentration exceeding WHO guideline for at least one metal. The main contaminants are Mn, Fe, As and Al. According to them, metal concentration in ground water seems to be controlled by the adsorption process.
Diop et al., (2014) also examined trace metal in water column in Dakar coast and Saint Lois estuary from Senegal, West Africa using ICPOES and ICPMS. Their results suggest that mobility of trace metals in the estuary is controlled by dissolved organic carbon. The result also indicates higher pollution of trace metals in Senegalese coast than other coast around the world. According to them speciation of heavy metal is influenced by dissolved organic contents in the estuary and chloride in the coast.
Ghazban et al., (2015) determined the concentration of Cd, Cu, Pb, Co and Zn in sediments and waters in Baychebagh copper mine in Iran using ICPOES. Enrichment factor signified that Pb, Cu and Cd were significantly enriched which indicates environmental contamination the result of geoaccumulation index indicates that sediments are unpolluted with respect to Co and Zn, Cu fall within unpolluted to moderately polluted range while Cd and Pb is highly polluted. The sediment quality guideline shows that Cd and Pb pose a serious risk to the environment.
Ige and Ogunsanwo, 2009evaluate the effects of leachate from open landfill in the Ita-Amo area of Ilorin, southwestern Nigeria. The study determined the possibility of upgrading the site to a modern Sanitary Landfill. Contanmination assessment and geotechnical properties of soils obtained over the site were investigated. Amadi et al.,2015 used geotechnical and mineralogical approaches to study open dumpsite in Minna North Central Nigeria. He uses his findings to proposed and design a modern sanitary landfill for the area. The study did not consider migration pathway. Amadi et al., (2016) consider integrated geosciences approaches using flow system, geotechnical, geochemistry and mineralogy of soil to carry out preliminary investigation for an open dumpsites in Minna, Niger State.