Environmental Chp. 18

Cheapest and most effective way to reduce pollution

avoid producing it or releasing it into the environment

Secondary Treatment -

biological degradation of dissolved organic compounds Effluent from primary treatment transferred into trickling bed, or aeration tank Effluent from secondary treatment is usually disinfected (chlorinated) before release into nearby waterway.

Main source of waterborne pathogens

improperly treated human waste

Remaining Problems

About three-quarters of water pollution in the U.S. comes from soil erosion, air pollution fallout, and agricultural and urban runoff.

Methyl tertiary butyl ether (MTBE)

a suspected carcinogen found as a gasoline additive, now commonly contaminates groundwater.

Herbicide atrazine in Great Lakes

- Estimated 600,000 kg of the herbicide atrazine in the Great Lakes

Metals

- Many metals such as mercury, lead, cadmium, tin and nickel are highly toxic. - Highly persistent and tend to bioaccumulate in food chains

Nonmetallic Salts

- Many salts (esp. selenium and arsenic-based) that are non-toxic at low concentrations can be mobilized by irrigation and concentrated by evaporation, reaching levels toxic to plants and animals. - Leaching of road salts has had detrimental effect on many ecosystems. - Arsenic is in northeastern India and western Bangladesh groundwater

Serious sources of metal contamination

- Mine drainage and leaching of mine wastes are serious sources of environmental contamination. - In a Tennessee study, 43% of streams and 50% of groundwater contaminated by metals and acids from mine drainage

Most widespread toxic metal

- Most widespread toxic metal contaminant in North America is mercury (found in fish) - 600,000 American children have mercury levels high enough to cause mental and developmental problems and 1 woman in 6 has blood levels high enough to harm fetus

Acids

- Often released as byproducts of industry or mining -Coal mining is an especially important source of acid water pollution. -Many streams acidified by acid mine drainage are lifeless -Combustion of fossil fuels releases sulfuric and nitric acids that are deposited in water. -Thousands of lakes in northeastern US and Canada are empty of fish due to low pH.

Biochemical Oxygen Demand (BOD)

- amount of dissolved oxygen consumed by aquatic microorganisms. Used as a test for organic waste contamination, e.g., sewage.

Eutrophic

- bodies of water that are rich in organisms and organic material

Oligotrophic

- bodies of water that have clear water and low biological productivity

Atmospheric Deposition

- contaminants carried by air currents and precipitated into watersheds or directly onto surface waters as rain, snow or dry particles - Estimated 600,000 kg of the herbicide atrazine in the Great Lakes -Most thought to have been deposited from the atmosphere -Contaminants can also evaporate from lakes.

Point Sources

- discharge pollution from specific locations- easy to pinpoint and control Factories, power plants, drain pipes

Cultural Eutrophication

- increase in biological productivity caused by human activities Algal "blooms" often result- decomposition of the algae depletes oxygen in the water.

Coliform bacteria

- intestinal bacteria; used to detect water contamination by animal wastes - Drinking water generally disinfected via chlorination

Dissolved Oxygen Content (DO)

- measure of dissolved oxygen in the water Effects of oxygen-demanding wastes on rivers depend on volume, flow, and temperature of river water.

Primary Treatment

- physical separation of large solids from the waste stream- sterilized and put in landfill or used as fertilizer

Eutrophication

- process of increasing nutrient levels and biological productivity, a normal part of successional change in most lakes

Nonpoint Sources

- scattered or diffuse, having no specific location of discharge- hard to control Agricultural fields, feedlots, golf courses, construction sites, pet waste, septic effluent

How many lack adequate sanitation?

-At least 2.5 billion people in poor countries lack adequate sanitation, and about half of these lack access to clean drinking water. -Put another way, clean drinking water could save millions of lives a year!

Oil Pollution

-Few coastlines in the world remain uncontaminated by oil pollution. -3 to 6 million tons of oil are released into ocean each year, about half of which is due to maritime transport. -Major oil spills from transport, military conflict, oil drilling in risky locations such as the North Sea -There are plans to drill in seismically active California and Alaskan coasts.

-Two most important sources of toxic organic chemicals in water are:

-Improper disposal of industrial and household wastes -Runoff of pesticides from fields, roadsides, golf courses, and lawns.

Other Countries Also Have Water Pollution

-Sewage treatment in wealthier countries of Europe generally equals or surpasses the U.S. -In Russia, only about half of the tap water supply is safe to drink and in China 70% of surface waters are unfit for consumption. -The poorest countries of South America, Africa and Asia have disastrous water quality due to poverty, population growth and shift of polluting industries from countries where laws are strict to where they are lax. -The Yamuna River and 2/3 of the other surface waters in India are so polluted that it is dangerous to even have contact with the water.

Organic Chemicals

-Thousands of natural and synthetic organic chemicals are used to make pesticides, plastics, pharmaceuticals, pigments, and many other day to day products.

Surface water reservoirs supply much of our water

2008 EPA data show that 30 million people in the U.S. get water from community systems that don't meet all health-based drinking water standards An estimated 1.5 million Americans fall ill from fecal contamination annually Cryptosporidium outbreaks Milwaukee - in 1993 400,000 became ill and 100 died

Water Pollution

Any physical, biological, or chemical change in water quality that adversely affects living organisms or makes water unsuitable for desired uses can be considered pollution.

There Are Few Controls On Ocean Pollution

Coastal zone (e.g. bays, estuaries, reefs) often overwhelmed by contamination from heavy metals, toxic chemicals, oil, pathogens, sediment. These zones would otherwise be among most productive. Discarded plastics are non-biodegradable, last for years, and are carried by currents around the world. Often ensnare bird and mammals, choking them

Areas of Contention

Draining or filling of wetlands is regulated by Section 404 Farmers and developers consider this the taking of private lands

Natural or Artificial Wetlands

Effluent flows through wetlands where it is filtered and cleaned by aquatic plants and microscopic organisms. Living organisms (e.g. duckweed) can also be used to break down pollution in a process called bioremediation. Chemical processes, oxidation/reduction, chelation, precipitation, can remove toxins.

U.S. Clean Water Act (1972)

Goal was to return all U.S. surface waters to "fishable and swimmable" conditions For point sources, discharge permits and best practicable control technology (BPT) are required. Set goals of best available, economically achievable technology (BAT) for zero discharge of 126 priority toxic pollutants Agricultural runoff and urban nonpoint pollution is the largest source of surface water degradation, but regulation remains a problem.

Sediment

Human activities have accelerated erosion rates in many areas. Human-induced erosion and runoff contribute about 25 billion metric tons of sediment and suspended solids to world surface waters each year. Obstructs shipping channels, clogs hydroelectric turbines, smothers fish eggs, blocks out light needed for photosynthesis Sediment can also be beneficial e.g. building coastal wetlands and nourishing floodplain fields

Watershed-level monitoring

In 1998, EPA switched regulatory approaches. Focus is now on watershed-level monitoring and protection. States are required to identify waters not meeting water quality goals and develop total maximum daily loads for each pollutant and each listed water body.

Human Waste Disposal in many countries

In many countries, especially in Asia, "night soil" (human and animal waste) is spread on fields as fertilizer- can transmit disease. Until about 70 years ago, most rural areas in the U.S. depended on outhouses, which contaminated drinking water supplies. Development of septic fields which clean water by aeration and remove excess nutrients through bacterial action. Solids are pumped out and taken to a treatment plant.

Natural Processes

In many poor countries, outdoor urination and defecation is the norm. When population densities are low, natural processes can quickly eliminate waste, but in cities this is unworkable. A significant proportion of dust in Mexico City is actually dried feces- "brown snow."

thermal plume

Industrial cooling processes often use heat-exchangers to extract excess heat, and then discharge heated water back into original source Disrupts natural ecosystems Die off of heat sensitive organisms Other organisms are attracted to warmth, but die when flow of warm water is interrupted by plant shutdown e.g. manatees in FL. Cooling ponds or towers are required to reduce thermal pollution

bioremediation

Living organisms (e.g. duckweed) can also be used to break down pollution in a process

Infectious Agents

Main source of waterborne pathogens is improperly treated human waste -Animal waste from feedlots and fields is also important source of pathogens.

Human Waste Disposal

More than 500 pathogenic bacteria, viruses, and parasites can travel from human or animal excrement through water.

Low-Cost Waste Treatment

Natural or Artificial Wetlands

Oxygen-Demanding Wastes

Oxygen is added to water by diffusion, from wind and wave and water churning, and by photosynthesis - Oxygen is removed from water by respiration and oxygen-consuming processes.

Thermal Pollution

Raising (or lowering) water temperatures from normal levels can adversely affect water quality and aquatic life. Oxygen solubility in water decreases as temperature increases. Species requiring high oxygen levels are adversely affected by warming water. Humans cause warming by discharging heated water from power plants and other industries.

Vegetation Buffers

Riparian buffers can be used to control nonpoint sources, substantial zone of plants to be left between any development and a stream or lake

How can underground aquifers be contaminated

Septic systems, feedlot animal wastes, pesticides, illegal dumping of toxic waste, etc.

Land Management Controls Nonpoint Sources

Some main causes of nonpoint pollution: Agriculture Urban runoff from paved surfaces Construction sites waste disposal Generally, soil conservation methods also help protect water quality. Vegetation buffers (riparian buffers) near streams & lakes In urban areas, reducing materials carried away by storm runoff is helpful.

Unfunded Mandates

State or local governments must spend monies to comply with regulations but are not repaid by Congress.

Source Reduction

Studies show as much as 90% less road salt can be used without significantly affecting safety. Carefully dispose of oil Recover metals from industrial waste and sell them Elimination of the use of lead in gasoline led to a significant decline of lead in US surface waters

ppm support detritivores and decomposerrs

Water with < 2 ppm oxygen will support mainly detritivores and decomposers.

ppm will support desirable aquatic life

Water with an oxygen content > 6 ppm will support desirable aquatic life.

CERCLA (1980)

created Superfund program to clean up toxic waste sites Amended in 1984 by SARA, which provides immediate response in emergency situations and permanent remedies for abandoned sites

Red Tides

dinoflagellate blooms - have become increasingly common in slow-moving and shallow waters.

Clean Water Act (1972)

established a National Pollution Discharge System which requires a permit for any entity dumping wastes in surface waters and requires disclosure of what is being dumped. "Every water body shall be swimmable and fishable." Improvement in water quality, mostly due to sewage treatment and less industrial effluent But goals have not been fully met; 21,000 water bodies do not meet designated uses

Safe Drinking Water Act

regulates water quality in municipal and commercial systems

Tertiary Treatment -

removal of plant nutrients (nitrates and phosphates) from secondary effluent Chemicals which bind or natural wetlands In many U.S. cities, sanitary sewers are connected to storm sewers. Heavy storms can overload the system, causing by-pass dumping of raw sewage and toxic runoff directly into surface water.

Dinoflagellates

single-celled organisms that swim with 2 whip-like flagella. Can be very toxic to fish, some cases of poisoning in humans eating fish. Found in marine zones that are polluted due to eutrophication