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40 Cards in this Set
- Front
- Back
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Define Maximum Contaminant Level: |
the highest level of contamination allowed in drinking water. MCLs are enforceable. |
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Define Maximum Contaminant Level Goal: |
The level of contaminant in drinking water that is below the level where there is no known health risks. |
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Define Maximum Residual Disinfectant Level: |
The highest level of a disinfectant allowed in drinking water. |
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Define Biochemical Oxygen Demand: |
The amount of oxygen required by microorganisms for the oxidation of an organic substance that's biodegradable.
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Define Chemical Oxygen Demand: |
The amount of oxygen required tooxidize the organic substance by a strong oxidizing chemical. |
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Define Total Oxygen Demand: |
The amount of oxygen required to oxidize organic and inorganic compounds toCO2and H2Oin a platinum-catalyzed combustion chamber.
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Define Total Maximum Daily Load: What must the calculation include? |
The calculation of the max amountof a single pollutant that a water bodycan receive from point and non-point sources and still meet water qualitystandard. –a margin of safety to ensure that the water bodycan be used for the purposes the State has designated. –The calculation must also account forseasonal variation in water quality. |
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Define Reference Dose: |
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Define Reference Concentration: |
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Explain the Hydrologic cycle: |
1. Evaporation of water from the ocean's surface. 2. The water vapor condenses to form clouds - transported around the globe until it falls as precipitation. 3. When the water reaches the ground it either: -evaporate back into atmosphere -penetrate surface to become groundwater 4. Groundwater seeps back into oceans, rivers, streams, or transpires back into the atmosphere. 5. The balance of water that remains in called runoff - empties into lakes, rivers, streams, carried back to the ocean. |
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How much of Earth's water is freshwater? How much of that is surface water? Where do humans get most of their water? |
2.5% is freshwater 1.2% is surface water - serves life's needs. .49% of surface freshwater is in rivers - where humans get a large portion of their water. |
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Explain Point sources of water pollution: |
Occurs when harmful substances are emitted directly into a body of water. (BP oil well in the gulf of Mexico). |
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Explain Nonpoint Sources of water pollution: |
Delivers pollutants indirectly through environmental changes. ex: fertilizer from a field is carried into a stream by rain in the form of run-off. Much harder to control. |
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What % of point discharges is conventional industrial waste? Sewage treatment plants? |
32% of the point discharges. 66% is from sewage and sewer overflows. |
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What are the 6 types of water pollutants? |
Toxic substances - metals, solvents, pesticides, etc. Suspended Solids - enter a water column by turbulence. During construction, soil, rock, fine powder enters rivers and causes it to become turbid (muddy, silted). Suffocates fish. Dams for hydroelectric power reduce sediment and nutrient movement from rivers to seas. Oxygen demanding waste - microorganisms in water feed on biodegradable substances, use all the oxygen and then die. anaerobic microorganisms prosper and produce toxins like ammonia and sulfides. Nutrient waste - Nitrogen and phosphorus needed for plant growth, found in wastewater and fertilizers. Run-off causes excess weed and algae growth and contaminates drinking water. Algae uses all the oxygen. Microbiological Pollution - Natural form of pollution. Cause animals and humans to become ill, need to be filtered out. Can cause cholera. Heat/Thermal pollution - from factories and power plants. Raises the temperature and reduces the amount of oxygen |
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What is Eutrophication? |
When water bodies receive excess nutrients that stimulate excessive plant growth. Nutrients come from fertilizers. Results in hypoxia (low concentration of dissolved oxygen in the water. |
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Explain the eutrophication process: |
1. increased nutrients (primarily phosphorus) 2. increased growth of primary producers (algae) 3. increased O2 use for photosynthesis 4. reduction in water transparency 5. plants and algae die (increased dead organic matter) 6. increased bacteria feeding on the dead matter 7. reduced oxygen concentration - bc bacteria use it. 8. reduced species populations |
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Explain dead zones: |
Algal blooms from excess nitrogen and phophorus produce "dead zones" in water bodies where dissolved oxygen levels are too low for most aquatic life to survive. |
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Define flocculation: |
A gently mixing process which induces particle collision and allows the formation of large particles which then settle out of the water. |
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Define Coagulation: |
Chemical coagulation - the addition of chemicals (coagulant) to water from the reservoir in a mixing tank that causes small and suspended solids to coagulate into large particles. Alum and iron salts, or synthetic organic polymers are used for coagulation. |
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Explain sedimentation and filtration: |
Enters a sedimentation tank - flocs settle by gravity. The clarified water is filtered to removed flocs that fail to settle. The resulting flocs are called sludge and must be collected, treated, dewatered, and disposed of per the clean water act. |
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Explain the disinfection process: |
Chlorination uses chlorine gas, sodium hypochlorite, or calcium hypochlorite - most common method. Reverse osmosis uses a semipermeable membrane to remove ions, molecules, and larger particles from drinking water to purify. |
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What are the 4 disinfection by-products that can be created? |
Trihalomethanes Haloacetic Acids Bromate Chlorite |
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What are the 6 major statutory provisions of the Clean Water Act? |
Title I - includes a declaration of goals and policy Title II - grants for construction of treatment works Title III - standards and enforcement Title IV - permits and licenses Title V - general provisions Title VI - state water pollution control revolving funds |
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What does title III (standards and enforcement) prohibit? |
Prohibits the discharge of any pollutant by any person except in compliance with the act. |
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What does title V (general provisions) work to do? |
Any US citizen may file a citizen suit against anyone that allegedly violated a regulation against the EPA and clean water act. |
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What are the 7 cardinal rules of risk communication? |
1. Accept the public as a partner. 2. listen to the public. 3. Be honest and flexible. 4. Coordinate and cooperate. 5. Meet the needs of the media. 6. Speak clearly with empathy. 7. Plan carefully and assess activities. |
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Define risk assessment and risk: |
Risk assessment - the methodology of estimating qualitative or quantitative risk. Risk - the probability of a given harmful outcome. |
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What is the primary focus of most federal agencies involved in risk assessment? |
Human risk assessment - the impact of pollutants on humans. |
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What does risk assessment include? |
Hazard identification Dose response assessment Exposure assessment Risk characterization |
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What does risk management include? |
Risk characterization Determination of acceptable risk level Control decision Control alternatives |
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Which step is risk characterization and what is its purpose? |
the FINAL step in risk assessment the FIRST step in risk management purpose is to present the risk manager a synopsis of all the data. |
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Define hazard identification: what does it include? |
process of determining if exposure to an agent can cause in increase in adverse health effect. includes characterization of the nature and strength of the evidence of causation. |
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Define weight of the evidence: |
summarizes the highlights of the information from supportive studies. |
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What types of studies can be used for evidence? |
human epidemiology animal bioassays supporting studies - (provides support rather than definitive info) |
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What is a dose response evaluation? |
a quantitative evaluation of toxicity information. |
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What does a dose response evaluation characterize? What does this relationship yield? |
the relationship between chemical and incidence of adverse health effects.
yields toxicity values (reference dose, benchmark dose). |
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What are toxicity values used for?
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to estimate the potential effect as a function of human exposure to the chemical. |
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What is exposure assessment? |
the consideration of the size and nature of the populations exposed AND the magnitude, frequency, duration, and routes of exposure of the target population. |
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What kind of information is needed for exposure assessment? |
level and distribution of contaminate number of people exposed sources apportionment dose at target |
