Water Pollution
Water Pollution Overview Sewage dumping
Ocean Pollution Water Pollution Overview
Urban Water Pollution Water Pollution Overview
Water Pollution Overview Urban Runoff
Water Pollution Overview Eutrophication
Water Pollution Overview Agricultural Runoff
Water Pollution Overview Acid Mine Drainage
Water Pollution Overview Unsafe drinking water and disease
Water Pollution Overview Erosion and sediment deposition
Water Pollution Overview Oil Spills
What is water pollution? Any physical, biological or chemical change in water quality that adversely affects living organisms or makes the water unsuitable for desired uses Review: point sources nonpoint sources Make sure you know examples of these!
Types of Water Pollution (fresh water mainly) Infectious agents Oxygen demanding wastes Plant nutrients and Eutrophication Toxic inorganic materials Organic chemicals Sediment and suspended solids Thermal pollution/ thermal shock
1. Infectious Agents
Safe to Swim?
Infectious Agents Most serious water pollutants in terms of human health Ex. typhoid, cholera, dysentery, polio, hepatitis 25,000,000 deaths each year (2/3 of child deaths, 80% of sickness in developing countries) Comes from untreated human wastes and animal wastes 2.5 billion people lack sanitation (more lack clean water)
How to test for unsafe water Water that is unsafe to drink usually has many types of bacteria in it. Instead of testing for all types, usually the common coliform bacteria is measured one colony of bacteria per 100ml is considered unsafe to drink by WHO standards 200 colonies per 100 ml is considered unsafe to swim by EPA standards.
2. Oxygen-demanding Wastes
Oxygen-demanding Wastes Healthy water has a high level of dissolved oxygen (> 8ppm) Oxygen-poor water (<2ppm) only supports detritivores Oxygen is added to the water by diffusion from air (affect of temperature) and photosynthesis Oxygen is removed by respirati on of plants and animals The addition of sewage and wastes stimulates oxygen consumption by detritivores
Measuring Oxygen Content BOD: Biological Oxygen Demand this measures the demand for oxygen that the detritivores place on the system how much O 2 is used by organisms over a 5 day period DO: Dissolved oxygen content how much oxygen is dissolved in the water is affected by temperature and aeration
Water Quality: DO
Oxygen Sag The oxygen sag is the pattern of dissolved oxygen in a stream that is being dumped into The pattern of organisms is determined by the DO content Know the different types of organisms and where they occur The length of the oxygen sag will depend upon how fast the stream is flowing, and how turbid it is
Oxygen Sag cont.
3. Plant Nutrients and Eutrophication
Eutrophication Water ecosystems (lakes) are usually limited by the amount of nutrients in them. Over succession, lakes gradually increase in nutrients and productivity Humans artificially increase the amount of nutrients in lakes through fertilizers, run-off The increase in nutrients leads to a series of stems culminating in eutrophication
Steps of Eutrophication Nutrients are added to water Increase in nutrients cause an algae bloom As the algae bloom progresses, the algae begin to die, and organic material accumulates on the bottom of the lake This material supports a boom in the decomposer populations The decomposers rapidly rob the lake of its oxygen, suffocating most other organisms in the process
What Eutrophication Looks Like
4. Toxic Inorganic materials
Toxic Inorganic materials Heavy metals: mercury, lead, cadmium and nickel lead pipes gold mining mining wastes, mine drainage tin on boat bottoms
Nonmetallic salts Occurs in desert soils As water evaporates, high levels of toxins are left behind Also from road runoff ex. selenium and arsenic also table salt in very high concentrations ex. Salton Sea
Acids and Bases Produced during leather tanning, metal smelting, plating, petroleum distillation and organic chemical formation Coal mining produced sulfuric acid ACID MINE DRAINAGE Acid rain (HNO3 and H2SO4)
5. Organic Chemicals
Organic Chemicals Pesticides, oils, plastics, pharmaceuticals, pigments, detergents, cleaning solutions, and paints DDT, etc. Stringfellow Site
6. Sediment and suspended solids
Sediment and suspended solids Largest pollutant by volume in most parts of world Erosion has increased sediment levels 25 billion metric tons of topsoil from runoff and erosion 50 billion from grazing, construction etc. fills reservoirs, fills shipping channels, less suitable for life, recreation Small levels of sediment are good
How sediments can be harmful
7. Thermal Pollution
Thermal Pollution Raising or lowering temperature from normal levels Water temps are usually stable so organisms are poorly adapted to rapid change oxygen solubility decreases as temperature increases most happens in industrial cooling can be good for raising species that wouldn t be there otherwise but can be harmful--> manatees
Groundwater pollution
Relative Polluters of Rivers
1. Red tides Types of Ocean Pollution Storms bring nutrient-rich runoff to the oceans these nutrients cause a bloom in phytoplankton in the oceans
2. trash Types of Ocean Pollution
Types of Ocean Pollution 3. Oil Oil spills have occurred in most of the shipping lanes in the world (as of 1985) Large effects on sea surface critters
Spain - 2003
Types of Ocean Pollution 4. Sewer waste/runoff many countries of the world (inc. U.S.) dump their waste into ocean results in diseases, abnormalities in organisms
Water Pollution Solutions
Water Pollution Solutions Ban or regulate phosphate detergents advanced water treatment to remove them Control agricultural runoff revegetation, wetlands, riparian, reduce water runs off of farms, reclaim water Control urban runoff golf courses, lawns, pets etc.; reduce use Control sediments and acids from mines revegetation and sediment traps (ponds) Control streambank erosion and protect wetlands protect and revegetate
How is human waste controlled? Municipal Treatment Primary Secondary (Tertiary) Private Treatment septic tanks
Sewage Treatment
Treatment of Human Waste Primary treatment: taking out solids grating (removes debris) moving screen (takes out smaller pieces) grit tank (sand and gravel settle) primary sedimentation tank (sludge settles)
Treatment of Human Waste Secondary treatment: biological degradation aeration tank (or filter bed, sewage lagoon) fluid is mixed with a bacteria rich slurry air is pumped in which promotes bacterial growth bacteria and sludge is removed off the bottom (some is returned to inoculate the aeration tanks) water is sometimes chlorinated to kill bacteria, then released
Treatment of Human Waste Tertiary Treatment: removal of plant nutrients removal of nitrates, phosphates and other nutrients which can cause algal blooms this is accomplished by passage through a wetland or lagoon Sewage treatment works well except: water in storm drains gets no treatment during storms, raw sewage is dumped treated water still has environmental effects
Septic Tanks A house-by-house alternative to sewer systems Water is pumped into a tank oils rise to top, solids to bottom middle water is pumped into a series of pipes where it can evaporate and be worked on by bacteria Works well if maintained, but can leak into ground water
Clean Water Acts Federal Water Pollution Control Act Clean Water Act of 1972 (amended 1977) goal was to make all U.S. surface waters safe for fishing and swimming by 1983 and restores and maintain the chemical, physical and biological integrity of the nations waters established controls for each major type of pollutant provides billions of dollars for sewage treatment plants
Clean Water Acts Safe Drinking Water Act 1974 established minimum safe levels for drinking water Superfund established 1980 Water Quality Act 1987 established a national policy for nonpoint sources of pollution 1995 - discharges trading policy established
Is the legislation working? Some good news Between 1972 and 1992 the amount of rivers and lakes that are fishable and swimable has increased from 36% to 62% Average phosphorous levels have dropped from.12ppm to.079ppm DDT has dropped from 1.2ppm to.196ppm But, 44% of lakes, 37% of rivers and 32% of estuaries are unsafe for fishing and swimming so there is more to do.