1. Types, Effects, and Sources of Water Pollution
Fresh Water Pollution
Types, Effects, and Sources of Water Pollution

2. Major Categories of Water Pollutants
Infection Agents
Plant Nutrients
Bacteria, viruses, protozoa, and parasitic worms
Nitrate, phosphate, ammonium
Source: sewage, manure, fertilizers
Source: human and animal wastes
Sediment
Oxygen-Demanding Wastes
Soil, silt
Organic waste (animal manure, plant matter)
Source: land erosion
Radioactive Materials
Source: human sewage, feedlots, paper mills
Iodine, radon, uranium, cesium, and thorium
Inorganic Chemicals
Source: Nuclear and coal power plants, mining, nuclear weapons production
Acids, lead, arsenic, salts, fluorides
Source: surface runoff, industrial effluents, cleansers
Heat (Thermal Pollution)
Excessive heat
Organic Chemicals
Source: Water cooling of electric and industrial plants
Oil, gasoline, pesticides, detergents
Source: industrial effluents, solvents, runoff from farms
Major Categories of Water Pollutants

3. Measuring Water Quality
Fecal Coliform Test: measure number of colonies of coliform bacteria present in a 100 mL sample of water
Safe drinking water contains no colonies
Safe swimming water contains a maximum of 200 colonies
BOD Test: the amount of oxygen demanding wastes in water
The amount of dissolved oxygen needed by aerobic decomposers to break down organic materials in a certain volume of water
Chemical Analysis: determines the presence and concentrations of inorganic and organic chemicals
Indicator Species: can analyze tissues of organisms found in water, or do a biodiversity count
Measuring Water Quality

4. Dissolved Oxygen Content
Water
Quality
Good
8-9
DO (ppm) at 20˚C
Slightly
polluted
Moderately
Heavily
Gravely
6.7-8
Below 4.5
Below 4
Dissolved Oxygen Content

5. Sources of Water Pollution
Point Sources
Nonpoint Sources
Discharge pollutants at specific locations through drain pipes, ditches, or sewer lines into surface water
Factories
Sewage treatment plants
Underground mines
Oil tankers
Scattered and diffuse and hard to trace to a specific site of discharge
Acid deposition
Runoff
Logged forests
Urban streets
Lawns and parking lots
Sources of Water Pollution

6. Which is easier to monitor and control?

7. Freshwater Streams and Rivers
Water that flows recovers rapidly from degradable oxygen-demanding wastes and thermal pollution (dilution)
This works as long as the stream is not overloaded with pollutants and something does not reduce the flow of the stream (damming, drought, etc.)
Oxygen Sag Curve
Freshwater Streams and Rivers

8. Time or distance downstream
Clean Zone
Decomposition
Zone
Septic Zone
Recovery Zone
Normal clean water organisms
(trout, perch, bass,
mayfly, stonefly)
Trash fish
(carp, gar,
leeches)
Fish absent, fungi,
sludge worms,
bacteria
(anaerobic)
8 ppm
Dissolved oxygen
Biological oxygen
demand
Oxygen sag
2 ppm
Concentration
Types of
organisms
Time or distance downstream
Direction of flow
Point of waste or
heat discharge

9. What has been done? Water Pollution Control laws (1970s)
Increased the number and quality of waste-water plants in US and most other developed countries
Require industries to reduce or eliminate point-source discharges
Problem: the developing world
Problem: “accidents”
2014 Elk River chemical spill of MCHM
What has been done?

10. Freshwater Lakes Dilution does not work as well as in running water
Often contain stratified layers that do not mix
Have little flow
Ponds contain small volumes of water
Much more vulnerable to pollution
Plant nutrients, oil, pesticides, and heavy metals
Can kill benthic life, fish, and birds
Cultural eutrophication
Freshwater Lakes

11. Groundwater Pollution
Very vulnerable because it cannot effectively cleanse itself and dilute and disperse contaminants
Clean up is also almost impossible
Sources: storage lagoons, septic tanks, landfills, hazardous waste dumps, deep injection wells
We store gasoline, oil, solvents, and hazardous wastes in metal underground tanks that can leak over time
High health risks in drinking water
Groundwater Pollution