CES Cheat Sheet 2026

The 30 highest-yield CES facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Why is source reduction important in waste management? → It reduces the volume and toxicity of waste produced
2. Which agency enforces federal environmental laws in the U.S.? → Environmental Protection Agency
3. Hydrodynamic dispersion in a groundwater contaminant plume consists of: → Mechanical dispersion caused by velocity variations and molecular diffusion
4. Which law governs hazardous waste management in the U.S.? → Resource Conservation and Recovery Act (RCRA)
5. What is eutrophication and what causes it? → Excessive nutrient enrichment of water bodies causing algal blooms and oxygen depletion
6. Which statistical method is useful for interpreting environmental data? → Regression analysis
7. What is the role of GIS in environmental data analysis? → It performs spatial analysis and mapping
8. What is a biological indicator (bioindicator) species? → An organism whose presence, abundance, or condition reflects environmental quality
9. What is the purpose of a 'scoping' process in EIS preparation? → To identify the significant issues and range of alternatives to be addressed in the EIS
10. What is the primary federal law governing Environmental Impact Assessments in the United States? → National Environmental Policy Act (NEPA)
11. What is the primary driver of permafrost thaw feedback in Arctic regions? → Rising temperatures releasing methane and CO2 from previously frozen organic matter
12. Which of the following is a common method for managing solid waste? → Recycling
13. Which of the following best describes the concept of 'carbon sequestration' in environmental science? → The process of capturing and storing atmospheric CO2 to mitigate climate change
14. Which pollutant is primarily responsible for acid rain? → Sulfur dioxide
15. Under the Clean Air Act, which EPA rule first required large stationary sources to obtain permits for greenhouse gas emissions? → Tailoring Rule
16. Why is a chain of custody important in environmental sampling? → To track sample handling and prevent contamination
17. Which of the following is an example of a 'non-threshold' toxicant, meaning there is no exposure level considered entirely safe? → Ionizing radiation and genotoxic carcinogens
18. What is the Air Quality Index (AQI) used for? → To communicate daily air quality conditions and associated health risks to the public
19. What is the primary goal of environmental sampling? → To assess pollutant levels in environmental media
20. Which process is responsible for the largest natural flux of CO2 from terrestrial ecosystems to the atmosphere? → Soil and ecosystem respiration
21. Which tool is commonly used for collecting air samples? → Air sampling pump
22. What is a composite sample? → A blend of multiple samples to represent average conditions
23. In greenhouse gas accounting, which 'scope' refers to indirect emissions from the generation of purchased electricity consumed by a company? → Scope 2
24. What is the Endangered Species Act (ESA) designed to protect? → Species at risk of extinction and the ecosystems on which they depend
25. Which parameter is typically measured in water quality sampling? → pH level
26. What is considered a best practice for compliance with water quality regulations? → Conducting routine sampling and employee training
27. What is the significance of the LD50 value in toxicology? → The dose lethal to 50% of a test animal population in a specified time period
28. Which metric, expressed in years, describes how long a greenhouse gas remains active in the atmosphere after being emitted? → Residence time
29. Why are wetlands important in ecosystem management? → They provide stormwater control and habitat services
30. What is a nonattainment area under the Clean Air Act? → A geographic area that does not meet one or more NAAQS for a criteria pollutant