Water Pollutants Biological Physical Chemical

Biological Pollutants Consists of pathogens (disease-causing agents) Come from sewage Diseases include; Typhoid, cholera, dysentery, polio, infectious hepatitis, salmonella, E-Coli bacteria

Temperature Referred to as Thermal Pollution Gases do not readily dissolve in liquids with high temperatures. ↑T → ↓ DO Power plants sometimes use waterways to cool their equipment. Replaced waters are warmer than they were before causing DO ↓ Cooling towers can be built to cool the water before they are discharged back into the water body.

Dissolved Oxygen (DO) DO gets into the water by: 1) moving water (riffles, rapids, water falls, etc.) 2) photosynthesis of aquatic plants Gases do not readily dissolve in liquids with high temperatures. ↑T → ↓ DO

BOD (Biological Oxygen Demand) Can be used as a gauge of the effectiveness of wastewater treatment plants The amount of oxygen needed for microorganisms to break down organic waste material High BOD indicates high levels of organic contaminants in the water Sewage = organic wastes; decomposers work to break down the waste – which takes oxygen; ↑ BOD → ↓ DO

Dilution and decay of degradable, oxygen-demanding wastes and heat in a stream. Figure 21-4

Sedimentation Excessive amounts of suspended solids in water. Come from soil erosion Increases turbidity (the cloudiness or haziness of a fluid caused by suspended solids) which reduces the amount of sunlight that penetrates the water ↓ photosynthesis → ↓ DO Slows water flow → ↓DO

Chemical Pollutants pH plant nutrients heavy metals radioactive substances

pH 3.0 – 3.5 = toxic to most life 3.5 – 4.0 = lethal to trout and other fish 4.0 – 4.5 = fish eggs; dead lake 5.0 – 6.0 = changes ecology (biodiversity, #, decline is fish species, slow decomposition, nutrients trapped at bottom, algae disappears) 6.5 – 9.0 mostly harmless 9.0+ harmful to lethal as pH goes up to 11.5

Plant Nutrients Nitrites/nitrates; phosphorous increases plant growth; sources: fertilizers, sewage causes algal bloom; eutrophication ↑ plant life → blocks sunlight → ↓ photosynthesis → plants die → ↑BOD → ↓DO → fish kill

Heavy Metals – Mercury (Hg) Sources leaching of soil due to acid rain, burning coal, industrial, household and mining wastes. Health Concerns damages nervous system, kidneys, vision, Minimata 1932 – 1968 – Co dumped 27 tons mercury compounds into Minimata Bay – Hg converted to methyl mercury – ingested by eating fish – 43 people died

Heavy Metals – Lead (Pb) Sources: paint, mining, incinerator ash, lead pipes and solder (contaminate water), auto exhaust Health Concerns damage to kidneys, nervous system (brain), ability to learn, depressed biosynthesis of proteins, nerves, red blood cells; anemia, irritability

Heavy Metals – Cadmium (Cd) Sources: electroplating, mining, plastic industries, sewage Health Concerns kidney disease

Heavy Metals – Arsenic (As) Sources: herbicides, wood preservatives, mining industry Health Concerns Damage to eyes, skin, GI tract, liver; cancer

Heavy Metals – Aluminum (Al) Sources: leaching due to acid rain Health Concerns anemia, loss of bone strength; possible role in dementia, and Alzheimer’s

Radioactive Substances oceans become contaminated by nuclear waste from illegal dumping, bomb tests, and nuclear accidents

Monitoring Water Pollution Nitrate and Phosphate tests Fecal Coliform Test Heavy Metal Tests BOD Changes in biodiversity of ecosystems Mortality of indicator species DIRECT TESTS INDIRECT TESTS

Point Source Pollution a single identifiable localized source of pollution easier to control emission, attribute responsibility and take legal action Ex) Water pollution from an oil refinery wastewater discharge outlet

Non-Point Source Pollution Derived from many different sources often in the form of runoff It is difficult to regulate.

Reducing Water Pollution through Sewage Treatment Primary and Secondary sewage treatment. Figure 21-16

Waste Water Treatment Removes the following: Silt Phosphorus Dissolved organic wastes Sludge Sewage adds nitrogen and phosphorus to the water which can lead to eutrophication in bodies of water Fecal coliform test is used to detect sewage in contaminated water

Sewage Treatment Natural and artificial wetlands and other ecological systems can be used to treat sewage.( Bioremediation)

Bioremediation the use of microorganismal metabolism to remove pollutants. Composting can be classified as bioremediation Heavy metals are not easily treated by bioremediation

Bioremediation

Phytoremediation consists in mitigating pollutant concentrations with plants able to contain, degrade, or eliminate pollutants from water, soil, or air Pollutants include: metals, pesticides, solvents, explosives, crude oil and its derivatives, and other contaminants

How do plants do what they do?