Lecture 8: Water Pollution

Lecture 8: Water Pollution

• Water: hydrologic cycle and watersheds• Types of Water Pollutants

– Pathogens– Organic Waste– Chemical Pollutants– Sediments– Nutrients

• Eutrophication• Anoxic Gulf Coasts Waters (a.k.a. The Dead Zone)• Sewage• Clean Water Act• Safe Drinking Water Act

Water Pollution, Intro• Any “bad” substance on the surface may

contaminate the hydrosphere, whether it is the contamination of lakes, streams, and oceans or whether it is the contamination of ground water.

• Water pollution has several environmental consequences, – Health hazards: many pathogens are waterborne and

are highly correlative to poor water quality..– Loss of biodiversity = polluted water bodies or ones

with excess organic and/or nutrients become anoxic and almost abiotic.

– Loss of aesthetic beauty– Impact on leisure and other outdoor/sporting activities

Hydrologic Cycle

• Water migrates between the atmosphere, the land, underground, and so forth.

• When examining the different types of water pollutants, I would like for you to put them within context of the Hydrologic Cycle.

Review the Hydrologic Cycle

Water on the surface can do one of three (or four) things: a) evaporate back to the atmosphere, b) percolate into the ground to become ground water, or c) run-off downstream (alternatively d. become part of a glacier).

From McKnight, Physical Geography

Watersheds

• Watershed = area that shares a common drainage network.– Fluids (runoff, chemical spills, etc.) on the landscape move

downstream, aggregating in larger and larger channels. – Pollution in one location, especially if released in the upland

areas, may contaminate the entire watershed due to the interconnectivity.

• When examining the different types of water pollutants, their source area, and their effect on the environment I would like for you to keep the watershed concept in mind.

• Please look at the watershed address locator webpage from EPA to find your home watershed:– http://www.epa.gov/win/address.html

Watershed

From McKnight, Physical Geography

Pollution• Pollution = “the presence of a substance in the environment that,

because of its chemical composition or quantity, prevents the functioning of natural processes and produces undesirable environmental and health effects”- EPA definition printed in your textbook.

• Pollution can be further subdivided into two sub-classes based on the source:– Point source = discharges of substances from factories, sewage,

industry, etc.. The source is easy to identify, and thus regulation of point source pollutants is manageable.

– Non-Point source = the sources of this type of pollution is very difficult to identify. Non-point pollution (NPS) often originates from agricultural and urban runoff, rainfall and snowmelt, storm-water drainage, and atmospheric deposition. Because the source regions are unidentifiable, NPS are extremely difficult to manage.

Water Pollution

• Two basic strategies to managing the pollution are:– 1) to reduce or remove the source– 2) to treat or purify the tainted water

Point Source and Non Point Source Pollutants

Types of Water Pollutants

• The water pollutants that we will discuss in this lecture include:– Pathogens– Organic Waste– Chemical Pollutants– Sediments– Nutrients

Pathogens

• “The most serious water pollutants are the infections agents that cause sickness and death” .

• Waterborne diseases kill thousands of people per year. The majority of these pathogens are a result of contaminated water – unsanitary water associate with poor hygiene.

Source: Gleick, P. 2002: Dirty Water: Estimated Deaths from Water-Related Diseases, 2002 – 2020Pacific Institute Research Report

Source: Gleick, P. 2002: Dirty Water: Estimated Deaths from Water-Related Diseases, 2002 – 2020Pacific Institute Research Report

Pathogens (continued)

• Pathogens are related to poor sanitary conditions. In a sense, they are often a result of organic pollution

• Human and animal excrement in water bodies creates a suitable environment for these pathogens– The fluid medium allows for quick transmitting– People bathing or drinking in contaminated streams are exposed

to these pathogens– Improved sanitation and hygiene education have saved more

lives than medicine. That is, the best way to mitigate the spread of infectious waterborne diseases is to improve sanitary conditions.

Proximity of Wells and Outhouses

Organic Waste• Human and animal waste creates “serious problems”• Besides creating a pathogen-friendly environment,

excess organic wastes reduce the availability of dissolved oxygen in water.– aerobic bacteria and other decomposers breakdown organic

materials they consume oxygen through cellular respiration. More organic waste results in more aerobic decomposition, which ultimately lowers available oxygen.

• Biochemical Oxygen Demand (BOD) = measure of the amount of organic material in water in terms of how much oxygen will be required to break it down. The higher the BOD the greater is the likelihood that dissolved oxygen will be depleted.

Organic Waste, Animals

• Animal Feeding Operations, colloquially referred to as “Factory Farms” contain large quantities of livestock.

• The high concentration of animals generates a lot of waste. Some animals, such as hogs, produce substantially more excrement per pound than humans.

• The animal waste poses serious threats to the environment. It is high in organic materials, nutrients, heavy metals, and pathogens

Examples of AFO’s

• Stockyards

• Hog Houses

• Chicken Houses

www.ecohealth101.org/whats_left/eat3.html

http://www.goveg.com/photos_chicken11.asp,

EPA’s ‘Animal Feeding Operations’

• Animal Feeding Operations (AFO) are defined as “a lot or facility (other than an aquatic animal production facility) where the following conditions are met” (epa.gov): – “Animals have been, are, or will be stabled or

confined and fed or maintained for a total of 45 days or more in any 12-month period, and

– Crops, vegetation, forage growth, or post-harvest residues are not sustained in the normal growing season over any portion of the lot or facility” (epa.gov).

• AFO’s are treated as a point source of organic and nutrient pollution

Waste Lagoons

• Waste from the AFO are hosed into waste lagoons.

• Ideally within the lagoons the solids become concentrated as the water evaporates. The manure can then be used as a fertilizer.

• These waste lagoons can leak into the environment contaminating surface and ground water with organic waste, nutrients, heavy metals, and pathogens

Photo Source: Dairy Waste Pictorial, EPA Region 10 and Washington State Dairy Federation

http://lwcd.org/images/MCR_earthen_Waste_lagoon.JPG

Organic Waste and DO

• Typical Oxygen Depleting Properties of Various Materials

• Type of Material Oxygen Demand (mg/l)– Municipal Sewage, treated = 25– Municipal sewage, untreated = 250– Cattle feedlot runoff = 1,000– Milk-house wastes = 1,500– Silage stack leachate = 35,000– Cattle or hog manure = 50,000Cattle or hog manure = 50,000

• Source: Minnesota Pollution Control Agency• Note: cattle and hog waste is 200 times human waste!

Hog Farms in North Carolina• North Carolina is one of

the leading hog-producing States. Most of the hog farms are in the eastern half of the state.

• The heavy rain from Hurricane Floyd (1999) flooded many of the waste lagoons, and the organic pollution washed out across the landscape,

• Getting back to the watershed concept, where did all the flooded waste lagoon materials go?

Source: North Carolina in the Global Economyhttp://www.soc.duke.edu/NC_GlobalEconomy/hog/maps.php#map2b

•Famous photo from AP showingflooded hog farms after Hurricane Floyd. •The waste lagoons were inundated•There is a major concern about the ramifications of this waste polluting the local watershed and the nearby coastal waters.

Human Waste, Hurricane Katrina

• We all remember the images of a flooded New Orleans. The water that inundated the streets was full of waste.

news.nationalgeographic.com/.../photo8.html

news.nationalgeographic.com/.../photo8.html

Fecal Coliform

• Organic material such as excrement is decomposed by Fecal Coliform (FC) bacteria.

• FC (certain strains of E. coli and other bacteria) pass through the digestive tracks of animals.

• Their presence in the water column indicates contamination by excrement.

• The EPA measures FC concentrations as an indicator of water quality.

• Other strains of E.Coli from organic waste are more harmful, such as the recent outbreak of E. coli in spinach.

Recent E.Coli (different strain than the fecal coliform) Outbreak in

Spinach• FDA announced on September 29, 2006 that all spinach implicated in the current

outbreak has traced back to Natural Selection Foods LLC of San Juan Bautista, California. This determination is based on epidemiological and laboratory evidence obtained by multiple states and coordinated by the Centers for Disease Control and Prevention (CDC). Natural Selection Foods issued a recall of all implicated products on September 15, 2006. More specifically, Natural Selection Foods has recalled all spinach products under multiple brand names with a date code of October 1 or earlier. Five other companies have issued secondary recalls because they received the recalled product from Natural Selections. See below for a complete list of brand names that are subject to the recalls. Spinach processed by other manufacturers has not been implicated in the outbreak. Processed spinach (e.g., frozen and canned spinach) is not implicated in this outbreak.

• Although the current outbreak may ultimately trace back to a specific field(s), there has been a long history of E. coli O157:H7 outbreaks involving leafy greens from the central California region. Spinach processed by other manufacturers has not been implicated in this outbreak, however, based on discussions with the industry, and given the past E. coli O157:H7 outbreaks, FDA and the State of California expect the industry to develop a comprehensive plan which is designed to minimize the risk of another outbreak due to E. coli O157:H7 in spinach grown in central California. While this plan is under development, FDA and the State of California reiterate our previous concerns and advise firms to review their current operations utilizing the FDA's guidance for minimizing microbial food safety hazards.

• http://www.cfsan.fda.gov/~dms/spinacqa.html

Chemical Waste• “Water-soluble inorganic chemicals constitute an

important class of pollutants that include”– Heavy metals (lead, mercury, cadmium, nickel, Def

Leppard)– Acids from mine drainage– Road salts– Petroleum– Urban runoff– Pesticides, fungicides, herbicides

Chemical Pollutants

• Any noxious substance spilled on the landscape can contaminate the watershed. Toxic pollutants sometimes have very long residence time and can be very problematic to manage.

• The worst type of contamination is of the groundwater. Groundwater contamination is very difficult to manage.

Groundwater Contamination:What is on the surface that could contaminate the groundwater?

Sediments

• All streams transport some degree of sediments. • Development or construction within the watershed can

increase the amount of sediment in streams.• Excess sediment will “choke the stream”• The environmental effect is loss of biodiversity, change

in hydrology, and ruining the aesthetic beauty of the water body.

• Sediments also act as surface area for other pollutants, like heavy metals. So greater concentrations of sediments will directly result in higher concentration of other pollutants.

Fish are all dead! No light = no vegetation and the whole ecosystem dies.

Nutrients

• Naturally, nutrients are limited within many aquatic ecosystems. Plants often have to compete for nutrients.

• Phosphorus and Nitrogen are two very important nutrients that are usually in high demand by aquatic vegetation. Both these elements are in the building blocks of biological molecules (DNA, Protein, Fatty Acids).

• When there are too many nutrients, however, it throws the entire aquatic ecosystem at of whack.

• Aquatic systems with too many nutrients become eutrophic.

Eutrophication• Phosphorus and nitrogen in many aquatic systems are usually

limiting.• Aquatic vegetation exists in two general forms:

– Benthic = rooted in the substrate, usually multicellular vegetation– Planktonic = free-floating in the water column, often single celled

algae• In nutrient poor environments the benthic organisms have an

advantage over the planktonic. Because they are rooted they can draw upon nutrients within the sediment.

• Nutrient-poor aquatic ecosystems are called oligotrophic, which translates to “poorly fed”. It seems paradoxical that a poorly fed environment is usually the most biologically diverse.

Aquatic Vegetation

Eutrophication• Eutrophication translates to “well fed”, and it refers to

an aquatic or marine ecosystem with too many nutrients.

• The excess nutrients stimulate the growth of the plankton at the expense of the benthic vegetation. Being single-celled and having a quicker lifecycle, planktonic algae can rapidly respond to an influx of nutrients within the water column.

• The algal populations explode (the carrying capacity jumps dramatically).

• The abundance of algae decreases the biological productivity of the aquatic ecosystem

Eutrophication Continued• Planktonic algae can form a thick scum surface that

blocks out light to the benthic species. Aquatic vegetation that is mostly submerged below the water surface (submerged aquatic vegetation, SAV).

• In addition the algae blooms result in lots of dead algae . The dead algae along with the dead fish and other organisms creates an abundance of organic materials. This is broken down aerobically, which depletes the dissolved oxygen in the water.

• Once the dissolved oxygen is reduced very few organisms can survive in this hypoxic environment.

Eutrophic Pond

Eutrophic_pond.JPG (84KB, MIME type: image/jpeg) From Wikipedia

Dead Zone

• The “Dead Zone” is an area of hypoxic water that stretches along the Gulf Coast.

• The Mississippi River drains 31 US states and 2 Canadian provinces. It is one of the largest rivers in the world, and it drains the world’s best agricultural lands. The runoff of fertilizes from along the Mississippi River watershed empties into the Gulf of Mexico where it stimulates an algal bloom.

Dead Zone (hypoxia)

http://daac.gsfc.nasa.gov/CAMPAIGN_DOCS/OCDST/dead_zones.html,

Dead Zone

Sewage• We all know what we flush down the toilet or what we

pour down the drain. What happens to all that stuff?• In answering the above question, keep in mind the first

law of thermodynamics, the bit about neither being created nor destroyed but changing from one form to another.

• Just because you flush it doesn’t mean that it disappears forever.

Historical Context of Sewage

• Important note: prior to the 1970’s most of the raw sewage, the stuff coming out of the houses, was simply dumped into the environment – usually within rivers or oceans. The book mentions that the mistreatment of sewage is one of the main instigators of the Clean Water Act (1972).

• The Clean Water Act (CWA) helped establish modern sewage treatment by appropriating funds to local and state governments to build or revise existing plants.

Sewage Treatment• Modern Sewage Treatment = based on

the filtration and biological decomposition.

• The raw sewage contains at least these four components:– Debris (toilet paper, feminine products, other things that get

flushed)– Particulate organic mater– Colloidal dissolved organic mater (things in solution or partial

solution, like urine – Dissolved inorganic mater– Misc. Chemicals

Sewage Treatment

– Preliminary = the raw sewage flows out of your house to a sewer line, which eventually leads to a municipal treatment plant. In the preliminary stage the raw sewage is filtered through a 1” mesh. The solids and paper that accumulates on the mesh screen is raked off and transported to an incinerator or taken to a landfill.

Sewage Treatment

• Primary Stage = after passing through the preliminary filtration, the raw sewage flows to a circulation chamber. Here the sewage is slowly circulated – the change in the velocity causes the courser materials, such as grit and other bits of organics, to settle out. The stuff that settles at the bottom is referred to as sludge; it is removed and taken to a landfill by dump trucks. In addition, grease, fats, and oils will float on the surface. These fatty materials are siphoned off and merged with the sludge.

Sewage Treatment

• Secondary Treatment = in this stage of sewage treatment the remaining dissolved organics and nutrients are broken down via aerobic decomposition. The sewage is aerated with oxygen and decomposing bacteria are added. The bacteria “feed” on the organic materials left in the water and utilize the remaining nutrients.

• After biological decomposition, the water is then sterilized, by either chlorine or ozone gas. Then it is released back into the environment. Usually municipal treatment facilities pump the treated sewage into a river or pump it out into the ocean. Water exiting the sewage treatment facility (gray water) in many places is cleaner than that which comes out of your tap.

Secondary Treatment

Processing of sludge

Gray Water

• In many cities the water exiting the sewage treatment plant is reused. Some cities use gray water to water lawns.. However in major metropolitan areas where water is scarce – the desert west – gray water might be an option for drinking water?

Septic System

• Waste leaving the home flows through a septic tank. In the tank the solids settle towards the bottom. Here the organics breakdown through aerobic and anaerobic decomposition. The colloidal and dissolved inorganics flow out into the yard via a drain field. The effluent is supposedly filtered naturally by the lawns, gardens, and soil microbes.

Drain Field

Septic Tank Problems• Septic tanks have to be cleaned out about every 5

years depending on usage. If there are more solids than the system can handle, the tank will backflow and the sewage treatment becomes ineffective. Leaking septic systems or poorly working ones can leak too much raw sewage into the environment. If too much water passes through the septic system, it will turn the yard all mushy.

• Also if there are too many septic systems built within too small of an area, the sewage will not be properly filtered or broken down. The excess nutrients and organics will contaminate the groundwater.

Sewage Ponds

• Many newer communities are using sewage ponds to treat their waste. The sewage ponds also employ biological decomposition. In this case the raw sewage is pumped into a containing pond. The solids accumulate at the bottom of the pond. The organic materials are feasted on by decomposers. Aquatic vegetation is also planted. The vegetation uses the organics and nutrients as fertilizers.

Clean Water Act 1972

• The Clean Water Act is the sister of the Clean Air Act. It was the first legislation of its kind to protect the Nation’s waters and to create safe drinking water.

Clean Water Act

• During the Environmental Movement there was a push to clean up polluted water. This was in large part due to:– Accumulating sewage– Factory effluents from the Chemical

Revolution– People getting sick from polluted water (see

the movie A Civil Action).– The Cuyahoga River caught fire in 1967

Clean Water Act 1972• The Clean Water Act:

– Gave the EPA the power to set regulations on sewage effluent

– Appropriated funds to local governments to retool poorly working sewage treatment

– Gave power to the EPA to regulate the amount of pollutants emitted by factories

– Protected the US waterways (“Navigable Waterways”). Under this definition wetlands are designated “navigable waterways”, and the CWA gave power to the Army Corp of Engineers to protect wetlands.

• The Safe Drinking Water Act 1974 (from the same vein as the CWA) authorized EPA to regulate the quality of public drinking water and to set drinking water standards