Lecture 8: Water Pollution

Lecture 8: Water Pollution

• Types of Water Pollutants– Pathogens

–Organic Waste

– Chemical Pollutants

– Sediments

–Nutrients

Water Pollution• 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

• Water pollution sources can be from any component of this 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.

Watershed

From McKnight, Physical Geography

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”

• 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.

Point Source and Non Point Source Pollutants

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

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

• 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.

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.

Organic Waste

• 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

Hog Farms• 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?

•Famous photo from AP showing flooded 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

• 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.

• Other strains of E.Coli from organic waste are more harmful, such as a 2009 outbreak of E. coli in spinach in California. The spinach was shipped all over the U.S.

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.