MARIKI CHE 312

Page 1: Introduction to Groundwater Quality Issues

Importance of Water Sources

  • Human civilization and development rely on the availability of quality water.

  • Main sources of this water include surface water (lakes, rivers, dams) and groundwater.

  • Groundwater is essential for drinking, irrigation, and industrial use, particularly in arid and semi-arid regions.

Groundwater Contamination

  • The quality of groundwater is influenced by human and natural activities along water flow paths.

  • Contamination sources include:

    • Solid waste and wastewater disposal.

    • Inadequate water supply infrastructure in developing countries, leading to reliance on groundwater due to perceived purity.

  • Groundwater quality can be negatively impacted by both anthropogenic and natural factors.

Natural Contaminants

  • Soils and rocks contribute composite elements and compounds to groundwater.

  • Interaction between water and soil/rocks can introduce toxic metals and other contaminants.

Anthropogenic Contaminants

  • Activities such as industrial, domestic, and agricultural can introduce nutrients, heavy metals, and organic pollutants into groundwater.

  • Use of agrochemicals can further exacerbate contamination levels; for example, phosphorus fertilizers may contain heavy metals like Cd and As.

Health Risks Associated with Contaminated Groundwater

  • Elevated levels of heavy metals pose significant health risks, even at low concentrations, affecting essential biological functions.

  • Toxic metals in water can affect human, plant, and animal health through direct ingestion or secondary routes (like irrigation).

  • High concentrations of metals like Al, Cd, As, Pb, and others have been reported in recent studies, indicating severe pollution risks and necessitating investigation.

Page 2: Study Area Overview and Objectives

Study Area Description

  • Research conducted along the slopes of Mount Meru in Tanzania, specifically in Akeri, Kikwe Wards, and Usa River Township.

  • Geographic coordinates: Latitude 3°00.00 - 3°40.00 S, Longitude 36°00.00 - 37°.55.00' E.

  • Ecosystem features:

    • Various water sources including rivers, springs, and groundwater.

    • Rainfall ranges from 500 mm to over 1200 mm per year, which sustains these water systems.

  • The district is divided into three zones based on altitude and climate:

    • Highland/Upper Zone: 1440m to 1800m above sea level, 1000mm+ rainfall, agricultural focus on coffee, banana, and Irish potatoes.

    • Middle Zone: 1000m to 1350m, 500 to 1000mm rainfall, agriculture and livestock.

    • Lower Zone: 800m to 1000m, rainfall 300 to 500mm, reliant on irrigation for crops like rice and maize.

Objective of the Study

  • Evaluate levels of heavy metals (Al, As, Cd, Cu, Fe, Mn, Pb) in groundwater near populated areas on Mount Meru slopes to determine water quality and contamination patterns.

  • Aim to establish a better understanding of groundwater health risks due to potential toxic metal exposure.

Page 3: Methodology

Data Collection Techniques

  1. Reconnaissance Survey:

    • Identification and mapping of groundwater sources (boreholes, springs, shallow wells) between January and February 2013.

    • Data collected included depth and water levels.

  2. Sample Collection and Analysis:

    • 50 groundwater samples collected weekly during dry (August - October 2013) and wet (March-April 2014) seasons.

    • Collection techniques varied based on water source, ensuring fresh samples were analyzed duly treated for contaminants.

Analytical Procedures

  • Water samples analyzed for heavy metal content using Inductively Coupled Plasma Optical Emission Spectrophotometer (ICP-OES) methods.

  • On-site measurements for pH, temperature, electrical conductivity, etc., followed standard protocol using appropriate analytical instruments.

Page 4: Groundwater Quality Variation

Concentration Variation of Metals

  • Groundwater quality was found to vary based on sampling points, water source types, and seasonal changes.

  • Aluminum (Al):

    • Concentrations highest in spring water compared to boreholes and shallow wells.

    • Dry season ranged between 0.04-3.72 mg/l and wet season below detection to 3.14 mg/l.

  • Borehole Water:

    • Lowest Al concentrations compared to other sources, with a range of 0.07-0.34 mg/l (dry) and 0.02-0.66 mg/l (wet).

  • Shallow Wells:

    • Higher than boreholes but lower than springs; dry season: 0.05-1.28 mg/l; wet season: 0.04-0.71 mg/l.

Significant Findings

  • Concentrations of Al exceeded WHO drinking water recommendations, suggesting a health hazard in certain samples.

  • ANOVA revealed significant differences in Al concentrations among different sources with noteworthy higher levels in wet season spring samples.

Page 5: Summary of Toxic Metals Analysis

Sample Results Overview

  • Copper (Cu):

    • Highest in boreholes (mean of 0.02 mg/l) during the dry season, below detection in wet season across sources, variance dependent on rainfall.

  • Iron (Fe):

    • Notable concentrations in springs compared to other sources, variability across dry and wet seasons.

    • Significant p-values in ANOVA indicate noteworthy seasonal variations of Fe concentrations.

  • Manganese (Mn):

    • Variations observed are minimal across sources and seasons, but significant enough to merit attention following WHO guidelines.

  • Arsenic (As) and Lead (Pb):

    • Noted significantly high levels in various wells during the dry season, especially dangerous due to potential sources like agricultural runoff.

    • Seasonal measurements showed lower levels during the wet season, indicating rainwater's dilution effect.