investigation of ground water pollution at ewu-elepe dumpsite using magnetic and physico-chemical methods

Description

ABSTRACT

Groundwater pollution is imminent in most developing countries as a result of increased anthropogenic activities apart from possible natural pollutants. This study reviewed groundwater pollution and discussed possible remediation measures. Sources of pollution can be categorized into two major types: point source pollution and non-point source pollution. Point source pollution (e.g. municipal sewage treatment plant and industrial plant, intense evaporation in shallow aquifers, degradation of water sources in areas located in geothermal/volcanic fields, and rock oxidation) is a single identify localized source while non-point source pollution (diffuse sources such as human land use, land use changes, chemical reactions of elements in the air or in the water and pollutes runoff from agricultural areas draining into a river) is characterized by multiple discharge point. Point source is relatively easy to identify, quantify and control. On the other hand, non-point source is difficult to monitor and control because the pollution cannot be traced to a single point of discharge. Pollution occurrence depends on the level of contaminant transported. Contaminants can be transported through filtration, sorption, chemical processes, microbiological decomposition and dilution. In this study, an investigation of groundwater pollution was carried out ascertaining the level of metal pollution in water of the dumpsite of the study area. The samples were collected from different water source according to standard procedures and were analyzed for some heavy metals (Ni, Mn, Co, Cd, Cu, Pb, and Zn) using magnetic and physico-chemical method. The study concluded that there are presents of heavy metals on water waters around the Ewu-Elepe dumpsite and as such should be discouraged in its usage for consumption purposes as these highly toxic trace elements can be absorbed by plants. A well water  treatment should put into consideration in order to improve the quality of water supply in that environment.

CHAPTER ONE

1.0                                                         INTRODUCTION

1.1       Background of The Study

Water covers over 70% of the earth surface and is undoubtedly the most precious natural resource that exists on the earth. Without the seemingly invaluable compound comprised of hydrogen and oxygen, life on the earth would be non-existent. Water is a key ingredient surporting food production, sanitation and rural livelihoods, as well as ensuring continuity and functioning of ecosystem. It dictates the pace of settlement and agricultural and industrial development of any society and even in recent time, establishment of any human settlement is usually centered on available source of water supply and in modern time, issue of water has equally taken prominences in global matters (Merki et al., 2012).

The distribution of world’s water indicates that only 2.5% and 97.5% constitute fresh water and saline water respectively. 2.5% of the world’s freshwater, surface water and groundwater have 0.4% and 30.1% representations respectively (Merki et al., 2012). Most of the freshwater is locked up in ice caps at the Polar region. The distribution of world’s water skewed towards saline water dominance which placed restriction on its availability for humans, agriculture and industrial uses. Furthermore, more exacerbating was the rapid rise in world’s population that rose to 7.6 billion. At the beginning of the nineteenth century, the total world population crossed the threshold of 1 billion people for the first time in the history of the Homo sapiens. Since then, growth rates have been increasing exponentially, reaching staggeringly high peaks in the 20th century and slowing down a bit thereafter. The total world population reached 7 billion just after 2010 and is expected to count 9 billion by 2045 (Obiora et al., 2015). This population growth revealed unprecedented increase in the last 200 years as it took over 200,000 years of human history for the world’s population to reach 1 billion and only 200 years to reach 7 billion. The increase in population and its attendant problems (depletion of natural resources, environmental degradation, conflicts and wars, lack of adequate food, water, shelter, education and employment, high cost of living and increase in anthropogenic activities) have placed stress on the available global fresh water leading to water crisis in the world. The “looming water crisis” is becoming a major issue on the world agenda for the twenty-first century. The World Water Council presented the “World Water Vision” during the Second World Water Forum and Ministerial Conference at The Hague in March 2000 (Obiora et al., 2015). The Vision reported that 1.2 billion people or one fifth of the world population do not have access to safe drinking water, while half of the world population lack adequate sanitation. The Vision further states that rapidly growing cities, burgeoning industries and rapidly rising use of chemicals in agriculture have undermined the quality of many rivers, lakes, aquifers and also emphasized that the impacts of agriculture on water quality are less visible over time but at least as dangerous as industrial because many of the fertilizers, pesticides and herbicides used to improve agricultural productivity slowly accumulate in groundwater aquifers and natural ecosystems.

The term quality of groundwater refers to its physical, chemical, and biological characteristics as they relate to the intended use of water. Groundwater quality is threatened mainly by human activities, although harmful substances are sometimes introduced by natural processes. Sustainable groundwater management must be based not only on prevention of the over exploitation of groundwater resources but also on prevention of contamination because unlike treatment at the point of use, prevention protects all of the resource. However, economic activities (primary activities) which produce commodities (mining, agriculture) and secondary or industrial activities (energy production, manufacturing, building, etc.) in addition to services (including transport) and households activities result into generation of enormous waste products which threatens the environment and leads to increasing groundwater pollution. There are two main sources of groundwater pollution; point source and non-point source. In principle, waste sites can be isolated from the environment. This, however, is not possible with diffuse sources of contamination which are either introduced into the air or subsequently rained out or are used in agriculture and partly infiltrate into the subsurface. These sources, together with mine tailings and accidental spills of hazardous substances represent major threats to groundwater quality.

Understanding the physical environment of groundwater is important in its pollution evaluation. Groundwater is the great “unseen” salient element of the hydrologic cycle. Because it is out of sight it is frequently out of mind (Obiora et al., 2015). The groundwater regime is a dynamic system in which water is continuously in motion. In a typical groundwater system this movement occurs through extensive heterogeneous material via an interconnected geological framework.

Merki, et al., (2012) assessed the levels of some physical, chemical, biochemical and microbial water quality parameters in twelve hand-dug wells in Igbara area of South West region of Nigeria. From the results of analysis, it was discovered that most of the pollutants increased in concentration during the rainy season over dry periods. Coliform population, lead, nitrate and cadmium in most cases, exceeded the World Health Organization (WHO) recommended thresholds for potable water. It was therefore concluded that well water in the area is not safe for direct consumption. Regular monitoring of groundwater quality, abolishment of unhealthy waste disposal practices and introduction of modern techniques were recommended.

Longe and Balogun (2010) investigated the extent of groundwater contamination of six sampling points between 10 and 375 meters down-gradient of a landfill site.

From results of the analysis, it was discovered that the groundwater samples were generally acidic with a mean pH value of 6.13 which is below the World Health Organization WHO and Nigeria Standard for Drinking Water Quality (NSDWQ) guidelines for portable water, the study revealed that the quantity of the groundwater resource underlying soils landfill site has been moderately impacted.

It was also shown that nitrate, chromium and phosphate concentrations were above the highest permissible limits (WHO, 2004 NSDWQ, 2007). Observations revealed that with time, the accumulation of leachate at the base of the sanitary landfill can break through into the groundwater while gas emission also posed potential environmental and health risk. Yaya and Okafor (2010) also analysed the microbial status of groundwater and surface water in the Federal Capital City of Nigeria (Abuja), taking samples during the dry and rainy seasons. Result of the research revealed that coliform count in most of the water samples from borehole (deep well) satisfy the permissible level prescribed for drinking water in the two seasons in line with WHO and NSDWQ. This was not so for samples from rivers and streams in the same area.

1.2       Problem Statement

Inadequate solid waste management is a major environmental problem in Nigeria in general and in Ewu-Elepe in particular. The contributing factors range from technical problems, to financial and institutional constraints. There is an absence of any properly designed solid waste disposal facility in Ewu-Elepe road, therefore posing contamination risk to both ground and surface water. The pollutant species in the dumpsites will continue to migrate and attenuate through the soil strata and after ascertain period of time might contaminate the groundwater system if there is no action taken to prevent the phenomenon. Groundwater serves as the major source of water supply in Eru-Elepe road, and its contamination is a major environmental and health concern.

Indiscriminate refuse dump affects water quality which people seem not to be aware of and public education programmes that sensitize the public on the health implications of indiscriminate refuse dump are almost non-existent. Mass media seem not to be doing enough to create awareness about implications of indiscriminate refuse dump.

This research will investigate the ground water pollution in the studied area using magnetic and physico-chemical methods.

1.3       Aim And Objectives Of The Study

The aim of this study is to investigate the extent of water pollution from solid waste dumpsite at Ewu-Elepe of Ewu-Elepe off Ijede road, Ikorodu Local Government Area of Lagos State, Nigeria.

The objectives of the project are:

1. to identify the proximity of dumpsites to water wells in the study area;
2. to determine the physico-chemical characteristics, Total Dissolved Solid (TDS), Chemical Oxygen Demand (COD), chloride (Cl), total hardness, turbidity, sulphate (SO₄)barium, colour and pH of water in wells of the study area using magnetic and physico-chemical methods;

iii.       to assess the levels of heavy metal(iron, and barium) concentration in water from wells in the study are magnetic and physico-chemical methods.

1.4       Scope of the Study

The research work is mainly on groundwater quality of shallow wells (hand dug well) and deep wells (bore hole) within Ewu – Elepe dumpsite.

The study examines the nature and characteristics of solid wastes in the area and the effects of the dumpsite on wells close to and far away from it.

Four samples were taken, two deep (borehole) wells and two shallow wells (hand dug) respectively. From the two deep wells, the first deep well (borehole) which is the reference point is 25 meters deep and the other deep well (borehole) is 30 meters, which is 21 meters away from the dumpsite.

The third sample is a hand dug well which is 6.1 meters deep (20feet) and 9 meters away from the dumpsite.

The fourth sample is also a hand dug well which is 6.7 meters deep (22 feet), 13 meters away from the dumpsite.

The volume of each sample that was taken is 5 litres so as to examine the nature and characteristics of wastes which have affected the wells close to and far away from the dumpsite in the study area. The magnetic method data was obtained using Garmin GPS.

1.5       Significance Of The Study

This research will help to highlight the relationship between the physical state of an environment and the resultant health implications of mismanaging it. This will help physical planners and health workers coordinate their activities in relation to environmental health policy issues as well as to guide stakeholders on the environment, health water resources ministries, and community based organizations with best options for public campaign towards maintaining a clean environment.

This research will appraise the public health awareness of the implications of indiscriminate refuse dump in the studied area.

In addition, it is also hoped that the research outcome will contribute to the existing body of knowledge on the subject matter.

1.6                     Geology, Description of the Study Area

The study area, Ewu-Elepe dumpsite is situated in Ginti Estate, Ewu-Elepe off Ijede road, Ikorodu Local Government Area of Lagos State, Nigeria. It lies between Latitudes 06° 35¹ and 06° 36¹ North of the equator and Longitude 003° 34¹ and 003°35¹ East of the Greenwich. It is about eight (8) hectares and has been in operation since November 2008 till date.

The study area is located within the Eastern Dahomey Basin. The Dahomey Basin extends from southeastern Ghana in the West, through Southern Togo and Southern Benin Republic (formerly Dahomey) to Southwest Nigeria. The geologic succession in Lagos spans through the cretaceous Abeokuta Formation, which unconformably overlies the rocks of the basement complex to the Quaternary Deltaic Plain Sands (Obiora and Onwuka, 2015). Ikorodu is directly underlain by the Benin Formation, which consists predominantly of sands, sandstone with thin lenses of clays and shales. The study area consists predominantly of coastal sands and river alluvium. The Benin Formation consists of yellow and white, sometimes cross-bedded sand, pebbly beds and clays with some sandy clay lenses. The thickness is unknown except in the Niger Delta, where it is about 2,000 meters thick (Merki, 2012). It also contains plant remains in addition to planktonic foraminifera, which have been recovered from its lower part offshore; and these indicate a Miocene age. Its upper part is believed to be Pliocene to Recent.