Chapter 21

Water & Soil Pollution

Types of Water PollutionSewage

Disease-causing agents

Sediment pollution

Inorganic chemicals

Radioactive substances

Thermal pollution

EutrophicationNutrient enrichment of a standing water ecosystem

Ex: Many of the lakes in our area!!

Eutrophication

EutrophicationAs nutrient levels rise, algal numbers also increase. Then, dead and dying cells rot, decomposers consume them

and use up the oxygen. BOD or biological oxygen demand increases

and life is choked out (hypoxia).

Controlling Artificial Eutrophication

• H2O, sunlight, carbonate CO3, N, P, & other inorganic compounds are the main requirements for algal growth (limiting factors).

• If we limit the “P” (and even the N), we can slow eutrophication.

Organic Compounds

• Polychlorinated Biphenyls (PCB’s), Benzene, Chloroform, Dioxins, & Vinyl Chloride are examples that can be found in polluted water.

Lead (Pb)• Pb based paint was banned (for sale) in the

U.S. in 1978.• Pb additives were removed from U.S.

gasoline in 1986.• Pb enters the soil & groundwater from

incinerator ash that is dumped into landfills.• Pb enters your body via pesticides &

fertilizers on produce, canned foods, & dinnerware.

• Middle-aged men, pregnant women, & young kids face the greatest threat.

Mercury (Hg)• Liquid at room temp. & can vaporize.

• Liquid Gas Precipitation Contaminates Water

• Coal-fired power plants release the largest amount of Hg (33%).

• Technology is there to remove the Hg out of coal emissions but it is expen$ive.

• Municipal incinerators medical waste incinerators contribute as well.

Mercury (Hg)• Bacteria convert the Hg in the sediments to methyl

mercury. These compounds are highly toxic & remain in the environment for long periods of time.

• They accumulate into organisms found at the top of the food chain. Tuna, Shark, Swordfish, &marine mammals.

• 40 out of 50 states have released health advisories on Hg tainted seafood.

Red Tides

• Algal blooms due to marine algae.

• These can produce toxins that directly kill fish & birds, & work their way up the food chain to marine mammals & people.

• Causes?

Increasing temp?

Coastal Pollution?

Red Tides

“Dead Zone” in the Gulf Of Mexico

• Fertilizers flow from the mighty Mississippi into the Gulf of Mexico from Iowa, Wisconsin, & Illinois (31 states) every spring & summer.

• This Dead Zone causes Hypoxia and creates an area of no life, the size of New Jersey. Poses a serious threat to commercial fishing in the area.

Radioactive Substances

• These isotopes emit radiation.• Originate from mining of Uranium &

Thorium, nuclear plants, medical & scientific research facilities, & Radon from the earth’s crust.

• 12 sewage treatment plants have tested positive for low level radiation in the U.S. since the 1980’s.

Thermal Pollution

• Water is used to cool industrial plants (steam generated electric power plants) & is returned to waterways significantly warmer.

• This speeds decomposition and allows less oxygen to dissolve in the water. Fish become stressed, need more food, have to ventilate their gills more and thus have a shorter lifespan.

Sources of Water Pollution

Point Source vs. Non-point Source

Agriculture

Municipal sources

Industrial wastes

Sources of Water PollutionPoint Source: This is discharged into

the environment through pipes, sewers, or ditches from specific sites like

factories or sewage treatment plants.

Ex: Cyanide spill in Feb. 2000 contaminated the Tisza & Danube

Rivers.

Sources of Water PollutionNonpoint Source: (polluted runoff) is caused by land pollutants that enter

bodies of water over broad areas (not a single point.)

Precipitation carries pollutants and deposits them into lakes rivers,

wetlands, groundwater, & the ocean.

Soil erosion is a major source.

Sources of Water Pollution

Agriculture: 72% of water pollution comes from agriculture.

Sources of Water Pollution

Municipal sources contribute urban runoff from storm sewers and city

streets. Runoff contains salt, garbage,sediments, & traffic emissions.

Sources of Water Pollution

Industrial wastes:

Food industries organic wastes

Papermills & pulp mills sludge & chlorine

Electronics Cu, Pb, Mn, & other heavy metals (can be filtered)

Improving Water Quality

• Purification of drinking water through reservoirs (surface water source).

• Aluminum sulfate used to take particulates out

• Sand used to filter smaller particulates.

• Activated carbon used sometimes

• Disinfection via Chlorine, O3, or UV radiation.

Improving Water Quality• Municipal Water pollution has a nonpoint source

in urban runoff from sewers. This runoff is often worse than sewage itself.

• It contains asbestos, chlorides, copper, cyanides, grease, hydrocarbons, Pb, motor oil, organic wastes, phosphates, sulfuric acid, and Zn.

• Combined sewer systems (NY, San Francisco, Pittsburgh, Boston) mix human & industrial wastes with urban runoff. If too much rain drains into the runoff then the system can’t handle it. Thus combined sewer overflow flows into waterways without being treated.

Groundwater Pollution• 50% of the U.S. population receives water

directly from untreated groundwater.

• Pesticides, fertilizers, organic compounds, landfill seepage, underground storage tanks, backyards, golf courses, & agriculture all flow into our groundwater supply.

• 250,000 petroleum tanks are presently seeping into groundwater (conservative estimate).

Involve the use of Septic tanks and Leach fields

Individual Septic Systems

Laws Controlling Water Pollution

• Safe Drinking Water Act of 1974• Clean Water Act of 1972, 1981, & 1987• Refuse Act of 1899 (Used in Hudson River

case!)• 40% of America’s waters fail to meet Clean

Water Act standards.• 218 million Americans live within ten miles

of polluted water.

The Great Lakes hold 1/5th of the world’s fresh surface water!

Soil Pollution and Remediation

• Is any change in the physical or chemical composition of the soil that adversely affects living organisms.

• Includes salts, petroleum products, metals, fertilizers, and pesticides.

• Salinization of irrigated soils occurs over a long period of time but can lead to very poor soil conditions.

• In the past, the only way to “clean” soil was to incinerate it.

Effects of salt on plant roots

Current methods of cleaning soil

Now, there are other methods of cleaning soil…• Dilution (Rinsing it)• Vapor extraction (Air is pumped in to remove

volatile compounds)• Bioremediation (Use of bacteria to clean soil)• Phytoremediation (Use of plants to clean soil)