The effect of leachate seepage from a landfill site on the quality of an urban river, Densu, that is the one of the main sources of water abstracted for treatment for most residents in the Accra Metropolitan area was determined by measuring the levels of heavy metals (As, Pb, Hg, and Cd) in the seepage and in the river itself using Atomic Absorption Spectrometry methods.
Heavy metal concentration upstream before leachate contamination was low and within WHO limits. The mean concentrations of arsenic, lead, mercury and cadmium were 0.026mg/l, 0.957mg/l, 0.025mg/l and 0.005mg/l, respectively in the leachate. Mean heavy metal concentration, two hundred metres downstream from the leachate discharge point (where water is drawn for domestic and drinking purpose) was 0.008mg/l for arsenic, 0.393mg/l for lead, 0.001mg/l for mercury while cadmium was not detected. Lead exceeded the WHO acceptable limit of 0.01mg/l for drinking water. Mean levels in the corresponding sediment samples were 0.015mg/kg for arsenic, <0.001mg/kg for lead, 0.004mg/kg for mercury and cadmium 0.151mg/kg.
Contamination factors computed were less than one (CF<1) for arsenic and lead in the sediments which imply low contamination and moderate contamination for cadmium (1 ≥ CF ≥ 3). Seepage of leachate from the landfill site into Densu must be monitored to ensure the quality of River Densu especially when it is being used as a drinking water source by downstream communities.
Table of Contents
- Chapter One: Introduction
- Problem Statement
- Justification of the Study
- Objective of the Study
- Chapter Two: Literature Review
- Water Quality
- Anthropogenic Impacts on Water Quality
- Physical Indicators of Water Quality
- Conductivity
- Total Dissolved Solids
- Turbidity
- Color, Odor and Taste
- Chemical Indicators of Water Quality
- pH
- Hardness
- Sulphates
- Nitrates
- Phosphates
- Biological Indicators
- Heavy Metals
- Arsenic
- Exposure Route for Arsenic to the Environment
- Health Effects of Arsenic
- Lead
- Exposure Route for Lead to the Environment
- Effect of Lead on Aquatic Life
- Health Effects of Lead
- Mercury
- Exposure Route for Mercury to the Environment
- Health Effect of Mercury
- Cadmium
- Exposure Route for Cadmium to the Environment
- Health Effect of Cadmium
- Surface Water in Ghana
- Chapter Three: Materials and Methods
- Study Area
- Sampling Sites
- Sampling
- Sample Preparation
- Measurement of pH, Conductivity and TDS
- Analyses of Samples
- Digestion Procedure for Water
- Digestion Procedure for Sediment
- Statistical Analysis
- Contamination Factor
- Chapter Four: Results
- Chapter Five: Discussion
Objectives and Key Themes
The objective of this study was to assess the impact of leachate seepage from a landfill site on the water quality of the Densu River, a primary source of drinking water for Accra. This involved measuring heavy metal concentrations (arsenic, lead, mercury, and cadmium) in the leachate and river water using Atomic Absorption Spectrometry.
- Heavy metal contamination of the Densu River
- Impact of leachate seepage on water quality
- Assessment of heavy metal concentrations in water and sediment
- Comparison of heavy metal levels to WHO standards
- Evaluation of contamination levels using contamination factors
Chapter Summaries
Chapter One: Introduction: This chapter sets the stage for the study by introducing the problem of leachate contamination of the Densu River, a crucial source of drinking water for the Accra Metropolitan area. It highlights the significance of the research by emphasizing the potential health risks associated with heavy metal contamination. The chapter clearly states the study's objective: to determine the levels of heavy metals (arsenic, lead, mercury, and cadmium) in the river water and leachate to assess the impact of the landfill on water quality. The justification for the study underscores the need to protect public health and ensure safe drinking water for the community.
Chapter Two: Literature Review: This chapter provides a comprehensive overview of existing knowledge on water quality, focusing on the impact of anthropogenic activities, particularly the effects of heavy metal contamination. It systematically examines various physical, chemical, and biological indicators used to assess water quality, including detailed discussions of each heavy metal under investigation: arsenic, lead, mercury, and cadmium. For each metal, the chapter explores its sources, pathways into the environment, its impact on aquatic life, and its adverse effects on human health. This thorough review contextualizes the current study within the broader scientific understanding of water contamination and its implications. The inclusion of information on surface water in Ghana specifically grounds the research within its geographical and environmental context.
Chapter Three: Materials and Methods: This chapter meticulously details the methodology employed in the study, including the selection of sampling sites along the Densu River, the sampling procedures, and the sample preparation techniques. It describes the analytical methods used to measure the concentration of heavy metals in both water and sediment samples, focusing on the Atomic Absorption Spectrometry methods used. This chapter also explains the statistical analyses used to interpret the obtained data and the calculation of contamination factors to assess the level of contamination in the sediment samples. The precision in detailing these methods ensures the reproducibility and reliability of the research findings.
Chapter Four: Results: This chapter presents the quantitative findings of the study, systematically reporting the measured concentrations of arsenic, lead, mercury, and cadmium in the leachate and at different points along the Densu River. The results are presented in tabular form, showing mean concentrations, standard deviations, and ranges for each heavy metal in both water and sediment samples. The chapter also includes the computed contamination factors (CFs) for the sediments, indicating the degree of contamination for each metal. This detailed presentation of data provides the empirical basis for the discussion and conclusions presented in subsequent chapters.
Chapter Five: Discussion: This chapter interprets the findings presented in Chapter Four, analyzing the levels of heavy metal contamination in the Densu River in relation to WHO drinking water standards. It discusses the impact of the leachate seepage on the river's water quality, comparing upstream and downstream levels of heavy metals. The chapter also interprets the contamination factors (CFs), relating them to the level of contamination in the river sediments. By integrating the quantitative data with the literature review, this chapter offers insights into the ecological and public health implications of the observed contamination.
Keywords
Heavy metal contamination, leachate, Densu River, water quality, arsenic, lead, mercury, cadmium, Atomic Absorption Spectrometry, contamination factor, WHO drinking water standards, landfill, environmental science, Ghana.
Frequently Asked Questions: Assessment of Heavy Metal Contamination in the Densu River
What is the main topic of this study?
This study assesses the impact of leachate seepage from a landfill site on the water quality of the Densu River in Accra, Ghana, focusing on heavy metal contamination (arsenic, lead, mercury, and cadmium).
What is the objective of this research?
The objective is to determine the levels of arsenic, lead, mercury, and cadmium in the Densu River water and leachate to assess the impact of the landfill on water quality and potential health risks.
Which heavy metals were analyzed?
The study analyzed the concentrations of arsenic, lead, mercury, and cadmium in both water and sediment samples.
What methods were used to measure heavy metal concentrations?
Atomic Absorption Spectrometry (AAS) was used to measure the concentrations of heavy metals.
What are the key themes explored in the study?
Key themes include heavy metal contamination of the Densu River, the impact of leachate seepage on water quality, assessment of heavy metal concentrations, comparison to WHO standards, and evaluation of contamination levels using contamination factors.
How were the samples collected and prepared?
The chapter on Materials and Methods details the sampling sites, sampling procedures, sample preparation techniques (including digestion procedures for water and sediment), and the statistical analysis used.
What are the chapter summaries?
The document provides summaries for each chapter: Chapter One (Introduction) sets the context and objectives; Chapter Two (Literature Review) examines existing knowledge on water quality and heavy metal contamination; Chapter Three (Materials and Methods) details the methodology; Chapter Four (Results) presents the quantitative findings; Chapter Five (Discussion) interprets the results and their implications.
How were contamination levels assessed?
Contamination levels were assessed using contamination factors (CFs) calculated for the sediment samples.
What are the key findings of the study?
The quantitative findings (concentrations of heavy metals in water and sediment, and calculated contamination factors) are presented in Chapter Four. Chapter Five discusses these findings in relation to WHO drinking water standards and the impact on water quality.
What are the implications of the study's findings?
The discussion chapter interprets the results regarding ecological and public health implications of the observed heavy metal contamination in the Densu River, a primary drinking water source for Accra.
What keywords describe this research?
Keywords include: Heavy metal contamination, leachate, Densu River, water quality, arsenic, lead, mercury, cadmium, Atomic Absorption Spectrometry, contamination factor, WHO drinking water standards, landfill, environmental science, Ghana.
- Quote paper
- Anonym (Author), 2012, Assessment of Heavy Metal Contamination of the Densu River, Weja from Leachate, Munich, GRIN Verlag, https://www.grin.com/document/508368
