🌊 Environmental Management Study Notes: Water Quality and Availability (0680)

Hello future Environmental Manager! This chapter is all about arguably the most vital resource on Earth: water. We will explore where clean water comes from, why access is unequal, what happens when it gets polluted, and how we can protect ourselves from water-related diseases. Don't worry if some terms look new—we'll break everything down step-by-step!

Why is this chapter important? Water scarcity and pollution affect billions of people and drive conflict and disease. Understanding how to manage this resource is crucial for sustainable development.

1. The Basics: Where Does Fresh Water Come From?

Before diving into quality problems, let's quickly recap the sources of fresh water, which is water with a very low salt concentration (unlike oceans).

Key Sources of Fresh Water (4.3):
  • Rivers and Lakes: Surface water sources. Rivers are crucial for transport and direct consumption.
  • Reservoirs: Artificial lakes created by building dams across rivers to store water.
  • Aquifers and Wells:
    An aquifer is an underground layer of rock or sediment that holds groundwater.
    A well is dug down to access this groundwater.
  • Desalination Plants: Facilities that remove salt from seawater to make it fresh and potable (safe to drink). This is an expensive, energy-intensive process, usually used in dry, rich regions (like the Middle East).

Quick Review: Remember that most of the Earth's fresh water is actually locked up in ice sheets and glaciers (4.1), meaning only a small fraction is easily accessible in rivers, lakes, and groundwater.

2. Water Availability and Quality (4.5)

The biggest environmental challenge is not just having water, but having potable water (safe drinking water).

2.1 Global Inequalities in Water Access

The availability of potable water varies hugely around the world, leading to significant challenges.

  • Water-Rich Regions (Often MEDCs):
    • Have high rainfall or large, stable river systems.
    • Can afford advanced sewage treatment and purification systems (chlorination).
    • Generally, populations have easy, piped access to clean water.
  • Water-Poor Regions (Often LEDCs or Arid Zones):
    • Experience drought, low rainfall, or seasonal availability.
    • Lack the infrastructure (pipes, pumps, treatment plants) to deliver clean water.
    • Access is often poor in rural areas, requiring long journeys to collect water from untreated sources (wells, rivers).
Did you know?

In many LEDCs, clean water access in urban areas is generally better than in rural areas because urban centers are prioritised for infrastructure investment, though slums and informal settlements still often lack proper access.

2.2 The Potential for Water Conflict

When a river or aquifer crosses international borders, competition for the limited resource can cause water conflict.

  • If an upstream country builds a large dam or diverts water for irrigation, it reduces the supply available to downstream countries.
  • Example: Disputes over the water of the Nile River involving countries like Egypt, Ethiopia, and Sudan.

Key Takeaway: Clean water is unevenly distributed, often depending on geology, climate, and a country’s wealth to build necessary infrastructure.

3. Water Pollution: Sources and Impacts (4.7 & 4.8)

Water pollution occurs when harmful substances contaminate streams, rivers, lakes, or groundwater.

3.1 Sources of Water Pollution (4.7)
  1. Domestic Waste (Sewage):
    • Includes human waste and wastewater from kitchens/bathrooms, often discharged untreated, especially in rural settlements or large informal urban areas.
    • Impact: Introduces pathogens (disease-causing organisms) and nutrients into the water.
  2. Agricultural Practices:
    • Fertilisers: Excess nutrients (nitrates and phosphates) wash off fields into water bodies.
    • Pesticides/Herbicides: Toxic chemicals used to kill pests and weeds, which can harm aquatic life and humans.
  3. Industrial Processes:
    • Waste discharge containing toxic substances like heavy metals (e.g., lead, mercury) and chemical solvents.
    • Often released into rivers or lakes, making the water unsafe for human use and deadly for ecosystems.
3.2 Impacts of Water Pollution on People and the Environment (4.8)

Pollution has severe consequences:

A. Health Impacts (On People)
  • Risk of Infectious Bacterial Diseases: Polluted water containing sewage can spread diseases like Typhoid and Cholera. These are deadly, especially to children.
  • Toxicity: Drinking water contaminated with industrial toxic substances (heavy metals) can cause long-term illness, organ damage, and death.
B. Environmental Impacts

1. Eutrophication (Nutrient Enrichment)

This is a crucial process you must understand. It is caused by the runoff of excess nitrates and phosphates (from agriculture and untreated sewage).

  1. Excess nutrients enter the water body (e.g., a lake or river).
  2. Rapid growth of algae occurs—this is called an algal bloom.
  3. The dense surface layer of algae blocks sunlight from reaching underwater plants.
  4. Underwater plants die due to lack of light.
  5. Bacteria (decomposers) multiply rapidly as they break down the dead plants and algae.
  6. This decomposition process uses up huge amounts of dissolved oxygen in the water.
  7. The resulting low oxygen levels (hypoxia) kill fish and other aquatic organisms.

2. Bioaccumulation and Bioamplification

Some industrial toxins cannot be broken down by organisms. They build up over time—a process called bioaccumulation.

  • Bioamplification (or Biomagnification): This is the increased concentration of these toxic substances as you move up the food chain.
  • Analogy: Imagine a tiny plankton eats 1 unit of mercury. A small fish eats 10 plankton (getting 10 units of mercury). A large predatory fish eats 10 small fish (getting 100 units). The toxin becomes more concentrated at the top of the food chain, severely affecting top predators (including humans).

3. Acid Rain

Air pollution (sulfur dioxide and nitrogen oxides) causes acid rain, which lowers the pH of rivers and lakes. This acidification harms fish eggs and aquatic organisms, often wiping out entire populations in sensitive water bodies.

Key Takeaway: Pollution sources are often domestic, industrial, or agricultural. The major environmental impacts are nutrient-driven eutrophication and the concentration of toxins (bioamplification).

4. Strategies for Improving Water Quality (4.9)

We need robust strategies—involving individuals, communities, and governments—to clean up our water sources.

4.1 Improved Sanitation and Sewage Treatment

Effective management of sewage is the single most important way to prevent disease spread.

  • Improved Sanitation: Providing safe, clean toilets and disposing of human waste hygienically, especially in rural and low-income urban areas.
  • Treatment of Sewage: Modern sewage treatment plants follow stages:
    1. Primary Treatment: Screens and settlement tanks remove solids (sludge).
    2. Secondary Treatment: Bacteria break down organic matter in aeration tanks.
    3. Tertiary Treatment (Advanced): Removes final traces of pollutants, especially nitrates and phosphates (to prevent eutrophication). The water is often disinfected (e.g., using chlorine or UV light) before release.
4.2 Pollution Control and Legislation
  • Industrial Control: Strict legislation and heavy fines for industries that discharge toxic waste directly into rivers. Industries must pre-treat their waste.
  • Agricultural Control: Promoting sustainable farming techniques, such as using less fertiliser, creating buffer zones of vegetation near rivers to trap runoff, and better managing livestock waste.
  • Monitoring: Regular testing of river and lake water quality to identify sources of pollution quickly.

Common Mistake to Avoid: Don't confuse "sanitation" (dealing with sewage/waste) with "purification" (making water safe to drink).

5. Managing Water-Related Diseases (4.10)

Water-related diseases fall into two main categories: those carried by vectors (like malaria) and those spread through contaminated water (like cholera).

5.1 Controlling Cholera (Waterborne Disease)

Cholera is a severe bacterial infection causing extreme diarrhoea, spread when drinking water is contaminated by the faeces of an infected person.

Strategies to control cholera focus entirely on providing safe drinking water (potable water) and sanitation:

  • Safe Potable Water Supply: Ensuring reliable infrastructure separates drinking water from sewage.
  • Boiling Water: Killing all bacteria and pathogens through heating. This is highly effective but requires fuel/energy.
  • Chlorination: Adding chlorine to water supplies (at home or at treatment plants) to kill bacteria. This is a cheap and effective disinfectant.
5.2 Controlling Malaria (Vector-Borne Disease)

Malaria is caused by a parasite, transmitted by the bite of the female Anopheles mosquito. Mosquitoes lay their eggs in stagnant water (still puddles, ditches, etc.).

A. Describe the life cycle of the malaria parasite:

(Keep this explanation simple for the exam):

  1. An infected mosquito bites a human, injecting the parasite into the person's bloodstream.
  2. The parasites travel to the liver, multiply, and then enter the red blood cells, causing symptoms like fever and chills.
  3. When an uninfected mosquito bites the sick person, it picks up the parasite.
  4. The parasite multiplies inside the mosquito, ready to infect another human.
B. Strategies to Control Malaria:

Control strategies focus on treating infected people and eliminating the vector (the mosquito).

1. Antimalarial Drugs:

  • Treating infected people to kill the parasite and prevent transmission to others.
  • Preventive medication taken by travellers.

2. Vector Control:

  • Insecticides: Spraying mosquito breeding grounds or indoor walls (often controversial due to environmental impacts).
  • Draining Stagnant Water: Removing the habitat where mosquitoes lay eggs.
  • Biological Control: Introducing predators, like small fish, to eat mosquito larvae in water bodies.
  • Nets: Using insecticide-treated bed nets to protect people while they sleep (when the mosquitoes are most active).

3. Eradication:

  • The long-term goal of completely eliminating the parasite and the disease from a region (very difficult but achieved in some areas).

Memory Trick:

Cholera needs Clean Water (Boiling, Chlorination).

Malaria needs Mosquito Management (Drugs, Nets, Vector Methods).

Key Takeaway: Water management is directly linked to disease control. Cholera is tackled with clean water provision; Malaria is tackled by interrupting the parasite life cycle, primarily by controlling the mosquito vector.

Quick Chapter Review

Focus Areas:

  • Global distribution of potable water (rich vs. poor, urban vs. rural).
  • Sources of pollution (domestic, industrial, agricultural).
  • Impacts: Eutrophication, Bioamplification, Acid Rain, and Disease (Typhoid, Cholera).
  • Management: Sewage treatment, legislation, and specific disease control methods (Boiling/Chlorination for Cholera; Vector Control for Malaria).