CWD Water Quality & Management 2 — Questions and Answers
Question 1: Which parameter is most commonly used to assess the oxygen demand exerted by organic matter decomposition in wetland waters?
- Biochemical Oxygen Demand (BOD) (Correct answer)
- Total Dissolved Solids (TDS)
- Turbidity (NTU)
- Electrical Conductivity (EC)
Correct answer: Biochemical Oxygen Demand (BOD)
BOD measures the oxygen consumed by microorganisms decomposing organic matter and is a key indicator of organic pollution in wetland systems.
Question 2: A wetland exhibits a pH of 4.2. Which water source is most likely contributing to this condition?
- Carbonate-rich groundwater
- Sphagnum moss decomposition and organic acids (Correct answer)
- Agricultural irrigation return flow
- Municipal treated effluent
Correct answer: Sphagnum moss decomposition and organic acids
Sphagnum moss produces organic acids (particularly sphagnic acid) that acidify bog and fen waters, commonly driving pH below 4.5.
Question 3: Under the Clean Water Act Section 404, which agency issues permits for discharge of dredged or fill material into wetlands?
- U.S. Fish and Wildlife Service
- U.S. Army Corps of Engineers (Correct answer)
- U.S. Environmental Protection Agency
- National Marine Fisheries Service
Correct answer: U.S. Army Corps of Engineers
The U.S. Army Corps of Engineers administers Section 404 permits for discharges of dredged or fill material into waters of the U.S., including wetlands.
Question 4: Which wetland type is most effective at removing nitrogen through denitrification?
- Coastal salt marshes with high salinity
- Freshwater emergent marshes with alternating aerobic/anaerobic zones (Correct answer)
- Open-water lacustrine fringes
- Desert playas with ephemeral flooding
Correct answer: Freshwater emergent marshes with alternating aerobic/anaerobic zones
Freshwater emergent marshes with fluctuating water tables create aerobic-anaerobic interfaces that support both nitrification and denitrification, maximizing nitrogen removal.
Question 5: Hydrologic connectivity between a wetland and an adjacent stream primarily affects water quality by:
- Reducing sediment deposition within the wetland
- Transporting dissolved nutrients, sediments, and contaminants between systems (Correct answer)
- Increasing salinity of the wetland water column
- Decreasing biological oxygen demand in the stream
Correct answer: Transporting dissolved nutrients, sediments, and contaminants between systems
Hydrologic connectivity facilitates bidirectional transport of nutrients, sediments, and contaminants, making it a critical pathway for water quality exchange between wetlands and streams.
Question 6: Which of the following best describes eutrophication in a wetland system?
- Decrease in water temperature due to shading by emergent vegetation
- Nutrient enrichment leading to excessive algal and plant growth and reduced dissolved oxygen (Correct answer)
- Increase in salinity from evapotranspiration in arid climates
- Acidification from atmospheric deposition of sulfur compounds
Correct answer: Nutrient enrichment leading to excessive algal and plant growth and reduced dissolved oxygen
Eutrophication is driven by excess nutrients (especially nitrogen and phosphorus) that stimulate algal blooms, and decomposition of the resulting biomass depletes dissolved oxygen.
Question 7: A Rapid Assessment Method (RAM) for wetland water quality typically evaluates which suite of indicators?
- Soil bulk density, organic matter content, and cation exchange capacity
- Vegetation cover, hydrologic indicators, and visual water quality observations (Correct answer)
- Macroinvertebrate richness, fish assemblage, and riparian buffer width only
- Remote sensing NDVI values and LiDAR elevation data
Correct answer: Vegetation cover, hydrologic indicators, and visual water quality observations
RAMs typically combine rapid field observations of vegetation condition, hydrologic function, and visual water quality cues to score overall wetland condition without full laboratory analysis.
CWD Water Quality & Management 2
Which parameter is most commonly used to assess the oxygen demand exerted by organic matter decomposition in wetland waters?