I. Water Quality-Overview

1. I. Water Quality-Overview D. Types of Water Pollution

2. Objectives - students should: • Distinguish among major sources and types of potential contaminants of drinking and recreational waters. • List and describe problems associated with contaminated drinking water worldwide.

3. Water Pollution: • Water pollutants can be divided into several categories: • Disease-causing microorganisms. • Oxygen-demanding wastes. • Inorganic chemicals. • Organic chemicals. • Sediments. • Alien species.

4. Disease-causing microorganisms: • A variety of microorganisms found in water are capable of causing disease in humans (pathogens to be discussed later) • The primary source of these microorganisms is animal and human fecal contamination (e.g., feedlot runoff, natural animal wastes, or sewage contamination, combined sewer overflow).

5. Combined Sewer Overflow

6. Oxygen-demanding wastes: • Organic matter in water may be used as a nutrient source by aerobic microorganisms and deplete oxygen in water. • Biochemical Oxygen Demand (BOD) measures changes in oxygen over time due to microbes. • Chemical Oxygen Demand (COD) measures the oxidation of organic compounds by a chemical oxidant.

7. Inorganic chemicals: • Inorganic chemicals like acids, salts, and toxic metals can make water unfit for drinking, decrease crop production, or corrode metal machinery. • Inorganic plant nutrients like nitrates and phosphates can cause eutrophication, and oxygen depletion of water (e.g., in lakes).

8. Organic chemicals: • A variety of carbon-containing chemicals can threaten human or aquatic life. • Volatile Organic Compounds (VOC’s), like oil, gasoline, cleaning solvents, etc. • pesticides, plastics, other Synthetic Organic Compounds (SOC’s),

9. Sediments or suspended matter: • Insoluble particles of soil and other solids become suspended in water (primarily due to erosion). • Suspended solids can reduce photosynthesis in plants, and carry other contaminants, • Settleable solids (sediment) can destroy feeding and spawning grounds of fish, and clog lakes, harbors, streams, etc.

10. Alien species: • Artificially introduced species (whether accidentally or intentionally introduced), can outcompete native species. • This reduces the biodiversity of the aquatic system and can cause severe economic losses.

11. Types of water pollution: • Sources of pollution can be point (PS) or nonpoint (NPS). • Point sources discharge pollutants at specific locations and are easier to locate, regulate, and remediate. • Nonpoint sources cannot be traced to a single discharge point, and are difficult to monitor, regulate, and remediate.

12. River and stream pollution: • Flowing water recovers relatively quickly from oxygen-demanding wastes due to microbial action, dilution, and aeration. • BOD rises quickly, but decreases downstream from the discharge point. • Water quality in 60% of stream length in the U.S. has never been measured.

13. Lake pollution: • Lakes are more susceptible to contam-ination because of slower flow rates. • Stratification (layering) of lakes results in a lack of mixing. • Eutrophication. • Oligotrophic • Mesotrophic • Eutrophic

14. Groundwater pollution: • Groundwater flow generally slow & non-turbulent, so contaminants are not degraded quickly. • 50% of U.S. groundwater systems are contaminated with organic chemicals. • 25 to 75% of groundwater contaminated. • There are an estimated 1 million leaking underground storage tanks in the U.S.

15. Ocean pollution: • Ocean is the ultimate sink for all water. • Coastal estuarine areas (where rivers meet the sea) are especially vulnerable to runoff pollution. • The Chesapeake Bay is an example of how an estuarine area can be damaged by pollution from inland runoff.

16. Contaminated drinking water: • The World Health Organization (WHO) estimates that 1.5 billion people lack safe drinking water supplies. • 1.7 billion people lack adequate sanitation facilities. • 5 million people die each year from water- borne disease, primarily transmitted by oral-fecal route. • Most of the 13,700 people who die each day from waterborne diseases prevent-able by proper sanitation and clean drinking water are children under age 5.

17. Solutions to water pollution: • Prevention of contamination is a more economical and sensible approach: • Control disposal of hazardous waste. • Limit application of pesticides, fertilizers. • Above-ground storage of chemicals, etc. • Physical, chemical, and biological treatments can reduce water pollution (e.g., in natural and municipal systems).

18. Summary: • Sources of water pollution include chemical, physical, and biological contaminants. • Contaminated drinking and bathing waters may transmit infectious diseases through pathogens.