CPC CPC Environmental Chemistry & Regulations 2 — Questions and Answers
Question 1: Which greenhouse gas has the highest global warming potential (GWP) over a 100-year period on a per-molecule basis?
- Carbon dioxide (CO2)
- Methane (CH4)
- Nitrous oxide (N2O)
- Sulfur hexafluoride (SF6) (Correct answer)
Correct answer: Sulfur hexafluoride (SF6)
SF6 has an extremely high GWP of approximately 23,500 over 100 years due to its strong infrared absorption and long atmospheric lifetime of ~3,200 years.
Question 2: The Superfund program (CERCLA) in the US requires cleanup of:
- Active industrial facilities only
- Contaminated sites where hazardous substances pose public health or environmental risks (Correct answer)
- Municipal solid waste landfills only
- Nuclear power plant waste sites
Correct answer: Contaminated sites where hazardous substances pose public health or environmental risks
CERCLA (Comprehensive Environmental Response, Compensation, and Liability Act) establishes the Superfund to clean up uncontrolled or abandoned hazardous waste sites posing risks to health or the environment.
Question 3: Eutrophication of water bodies is primarily caused by excess inputs of which nutrients?
- Iron and manganese
- Nitrogen and phosphorus (Correct answer)
- Calcium and magnesium
- Potassium and sulfur
Correct answer: Nitrogen and phosphorus
Excess nitrogen and phosphorus from agricultural runoff and wastewater stimulate algal blooms; when algae decompose, bacterial respiration depletes dissolved oxygen, creating hypoxic zones.
Question 4: Which analytical method is preferred for determining volatile organic compounds (VOCs) in drinking water under EPA Method 524?
- High-performance liquid chromatography (HPLC)
- Purge-and-trap GC/MS (Correct answer)
- Atomic absorption spectroscopy (AAS)
- Ion chromatography
Correct answer: Purge-and-trap GC/MS
EPA Method 524 uses purge-and-trap concentration followed by GC/MS analysis to identify and quantify VOCs in drinking water at ppb and sub-ppb levels.
Question 5: The Clean Water Act's NPDES (National Pollutant Discharge Elimination System) permit program regulates:
- Air emissions from industrial stacks
- Discharges of pollutants into navigable waters of the US from point sources (Correct answer)
- Underground injection of hazardous waste
- Solid waste disposal in landfills
Correct answer: Discharges of pollutants into navigable waters of the US from point sources
NPDES permits set effluent limits for point sources (pipes, ditches) discharging pollutants into US waters, establishing technology-based and water quality-based limits.
Question 6: Acid rain is primarily caused by atmospheric reactions of which industrial emissions?
- Carbon monoxide and hydrogen
- Sulfur dioxide and nitrogen oxides (Correct answer)
- Volatile organic compounds and ozone
- Particulate matter and lead
Correct answer: Sulfur dioxide and nitrogen oxides
SO2 (from coal burning) and NOx (from combustion) react with water and oxygen in the atmosphere to form sulfuric and nitric acids, which lower precipitation pH.
CPC CPC Environmental Chemistry & Regulations 2
Which greenhouse gas has the highest global warming potential (GWP) over a 100-year period on a per-molecule basis?