Environmental Monitoring & Instrumentation Flashcards
6 cards from real ETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Environmental Monitoring & Instrumentation flashcards as text
A field technician uses a combustible gas indicator (CGI) and observes a reading of 10% LEL in a utility vault. What action should be taken?
Answer: Ventilate the space and continue monitoring before entry
A 10% LEL reading indicates a measurable combustible gas presence; standard practice requires forced ventilation and continued monitoring to trend whether concentrations are rising or falling before permitting entry.
Which EPA method is the standard for measuring total metals in water samples using inductively coupled plasma mass spectrometry (ICP-MS)?
Answer: EPA Method 200.8
EPA Method 200.8 is the standard aqueous method for determining trace elements in water by ICP-MS, providing low detection limits for metals like arsenic, lead, and mercury.
What is the significance of measuring oxidation-reduction potential (ORP) in a groundwater sample during field monitoring?
Answer: ORP characterizes the redox environment, which determines which contaminant degradation pathways are occurring
ORP (measured in millivolts) indicates whether subsurface conditions are oxidizing or reducing, which directly controls natural attenuation processes such as aerobic biodegradation, sulfate reduction, or methanogenesis.
When collecting a low-flow groundwater sample, what field parameter stability criteria typically indicates the sample is representative of aquifer conditions?
Answer: Three successive readings of pH within ±0.1 unit, conductance within ±3%, DO within ±0.3 mg/L, and ORP within ±10 mV
Low-flow sampling protocols require stabilization of pH (±0.1), specific conductance (±3%), dissolved oxygen (±0.3 mg/L), and ORP (±10 mV) across at least three consecutive readings before sample collection.
A technician uses an XRF (X-ray fluorescence) analyzer on soil at a brownfield site. What primary advantage does XRF offer compared to laboratory analysis?
Answer: XRF gives real-time, non-destructive elemental analysis enabling rapid site-wide screening
Portable XRF provides immediate, non-destructive elemental (metals) analysis in the field, allowing technicians to screen hundreds of locations per day and guide confirmatory sampling without waiting for laboratory turnaround.
What is the purpose of a 'trip blank' in groundwater or soil vapor sampling quality assurance?
Answer: To detect cross-contamination or VOC introduction from sampling equipment or field environment during sample transport
A trip blank (typically a VOC-free water vial prepared in the lab and carried through all sample handling steps) checks for contamination introduced from the field environment, equipment, or transport containers.