BI 105AEnvironmental Biology Professor Jill Nissen Montgomery College Fall 2006
Water Pollution Chapter 22
Water Pollution • Any physical or chemical change in water that negatively impacts the health of humans or any other organism.
Categories Of Water Pollution • Sewage • Disease causing agents • Sediment pollution • Inorganic plant and algal nutrients • Organic compounds • Inorganic chemicals • Radioactive substances • Thermal pollution • Mini-glossary, p. 488
Some Types of Water Pollution • Disease Causing Agents • Infectious agents such as viruses and bacteria. • Spread diseases such as typhoid, cholera, dysentery, and hepatitis. • Originate from waste of infected individuals. • Inorganic Plant & Algal Nutrients • Chemicals such as phosphorus and nitrogen. • Stimulate excessive growth of plants and algae, causing enrichment, bad odors, and high BOD. • Originate from animal waste, plant residues, and fertilizer runoff. • Inorganic Chemicals • Acids, salts, and heavy metals such as lead and mercury. • Associated with a variety of health problems specific to each contaminant. • Originate from industries, mines, drilling, and urban runoff.
3 Common Contaminants of the Chesapeake Bay • Bacteria: Sewage systems are one significant source. • Nutrients: Nitrogen and phosphorus from fertilizers. • Toxic Substances: Industries, agriculture, household chemicals and pesticides.
Fish Advisories • In many areas of the Bay, some fish have enough pollutants in their tissue that consumption should be limited or avoided • http://www.mde.state.md.us/CitizensInfoCenter/FishandShellfish/home/index.asp
Biochemical oxygen demand (BOD) • Biochemical oxygen demand (BOD) is the amount of oxygen required by microorganisms to decompose the organic substances in sewage. More sewage means higher BOD.
Anoxia • Dissolved Oxygen (DO) is the amount of oxygen present in the water, measured in milligrams per liter (mg/l). • Healthy Water = 5.0 mg/l or more of dissolved oxygen. • Hypoxia = low levels of dissolved oxygen (2.0 – 5.0 mg/l). • Severe Hypoxia = very low levels of dissolved oxygen (0.2 – 2.0 mg/l). • Anoxia = very little or no oxygen (0 – 0.2 mg/l). During the past two decades, summer-long anoxia has occurred almost yearly in the Chesapeake Bay
The Dead Zone • Just like humans, most living creatures in the Chesapeake Bay need oxygen to survive. • When the dissolved oxygen levels drop too low, many aquatic species die. • The Chesapeake Bay’s “dead zone,” stretches for hundreds of square miles during the summer.
Eutrophic • A body of water that is extremely rich in nutrients and is characterized with high biological productivity & biomass • Characteristics of a eutrophic lake: • Cloudy water. • Poor light penetration. • Often Shallow. • Oxygen deficient. • Can be accelerated by human activity. • Contains large populations of aquatic animals.
Oligotrophic • Lakes, estuaries, and slow flowing streams that have minimal levels of nutrients and lowest levels of biological productivity. • Characteristics of an oligotrophic lake: • Clear water. • Rich with Oxygen. • Low in Nitrogen. • Nutrients are short in supply. • Supports small populations of aquatic organisms. • Less plant debris accumulated on the bottom over the years.
Point Source Pollution is pollution that can be traced to a specific site: Oil spill Thermal pollution from a power plant Discharge from a sewage treatment plant Nonpoint Source Pollution is pollution that enters a body of water over large areas rather than at a single point: Agricultural runoff Mining wastes Sediments from construction Urban runoff Point & Nonpoint Source Pollution
Major Sources ofWater Pollution • Agricultural – Organic or inorganic pollutants in surface waters & groundwater (such as animal waste or sediment from eroded cropland). • Municipal – Waste water from homes and commercial establishments (including urban runoff & combined sewer system overflow). • Industrial – Pollutants in waste water from different industries (such as toxic compounds and sludge from paper mills).
Safe Drinking Water Act, 1974 • Established to have uniform federal standards to protect drinking water. • Requires the EPA to establish the maximum contaminant level, review risks in drinking water, and revise the drinking water standards. • The 1996 amendment requires water suppliers to tell consumers what contaminants are present in their water system.
Clean Water Act, 1977 • Established to eliminate discharge in waterways and achieve water quality safe for fishing, swimming, etc. • Requires the EPA to set and monitor national emission limitations. • Polluters must obtain permits or be fined. • The 1987 amendment expanded the system to include nonpoint sources, but they are more difficult and expensive to regulate.
How you can help • Dispose of household chemicals, medicines, and motor oil properly. • Pick up pet wastes, litter, leaves, and debris to keep them out of street gutters and storm drains. • Apply lawn and garden chemicals sparingly. • Drive less and make sure your car is well-maintained. • Wash your car on a porous surface such as your lawn.
Review Objectives Types of Water Pollution• Define water pollution.• List and briefly define eight categories of water pollutants.• Discuss how sewage is related to eutrophication, biochemical oxygen demand (BOD), and dissolved oxygen.• Describe water quality issues in the Chesapeake Bay.• Distinguish between oligotrophic and eutrophic lakes. Water Quality Today• Contrast point source pollution and nonpoint source pollution. Laws Controlling Water Pollution• Compare the goals of the Safe Drinking Water Act and the Clean Water Act.