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

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

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

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

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

Which is easier to monitor and control?

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

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

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?

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

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