Intro to sampling Adapted from “Fundamentals of Environmental Sampling and Analysis” by Chunlong Zhang

Why are you sampling? Comply with regulations! –Determine concentrations or loads Measure background, ambient concentrations –Determine degree of pollution –Identify trends (spatial, temporal) Detect accidental releases or evaluate risk –Risk to humans? Wildlife? Both? Study fate and transport, evaluate effectiveness of control or remediation strategies

Scientifically defensible data Can it stand up in court? Components of legal defensibility include (but are not limited to): –Custody or control (chain of custody forms, to prevent tampering) –Documentation (paper trail) –Traceability (esp standards – certificates of analysis)

Lab notebooks In govt and industry, lab notebooks are LEGAL DOCUMENTS –Date and signature are part of GLP –Do not remove pages or obliterate or erase anything. In academia, the rules are loose. –The lab notebook is your journal, diary, best friend. Make your notes excruciatingly detailed. –Why? To help YOU when you write up your data (sometimes years later)

Sampling issues Where to take samples When to take samples How to take samples How many samples to take How often samples will be taken How much sample is needed How to preserve samples How long the sample will be stable What to take (air, water, soil?) What to analyze (physical, chemical, biological) Who will take samples (sample custody)

Why is environmental sampling unique? Numerous analytes, high cost Many samples Sample matrices are complex, interferences are variable and unpredictable. Concentrations are low Some analyses must be done on site and/or continuously Analysts need to know not just how to analyze, but also be familiar with regulations Huge data sets require knowledge of statistics, data management

Jargon DQO data quality objectives –What are you trying to measure and why? Relative vs. absolute data, operationally defined parameters (i.e. organic carbon), total metals or speciation? QAPP quality assurance project plan QA/QC quality assurance/quality control Representativeness Many agencies (EPA, NIOSH, USGS, ASTM) have standard methods. Often your lab must be certified to produce results that are admissible in court or valid for regulatory purposes.

Hazards during sampling/storage Volatilization Change in speciation (dissolved/particle, metal speciation, degree of sorption) Biodegradation Photolytic degradation Chemical degradation (Cl 2 ?)

Sample containers and preservation Metals –Dangers are sorption to container and precipitation –Use plastic bottles; acidify to pH2 with HNO 3 VOCs –Danger is volatilization—avoid headspace Organics in drinking water –Danger is reaction with Cl 2 ; add Na 2 S 2 O 3 PAHs –Photochemical degradation; use amber glass All organics (some inorganics) –Biodegradation; freeze or refrigerate, add something to kill bacteria

Air sampling “Air” or atmospheric samples may consist of: –Gas phase –Airborne particles (aerosols) –Rain/snow precipitation

Why do air sampling? Comply with regulations –Ex. Ozone, PM2.5 Fate and transport (research) Loadings via atmospheric deposition Locate sources

Sampling for common air analytes High vapor pressure - Gas phase only –Ozone, NOx, VOCs –Continuous monitors (ozone, NOx) –VOC canisters Low vapor pressure - Particle phase and precip –Metals, nutrients (P) –Filters for particles, rain collectors for precip –No need to worry about gas/particle partitioning or gas absorption artifacts Intermediate vapor pressure - Gas, particle, and precip –Semivolatile organics (PCBs, PAHs, etc) –High volume air samplers to separate gas and particle phases Worry about changing gas/particle partitioning –Rain collectors with immediate solid phase extraction

Analyzing air samples VOCs –Purge and trap GC/MS Semivolatiles –Extract, cleanup, analyze by GC/ECD or GC/MS

Factors to consider when choosing a sampling/analysis method Quantity vs quality of data –Quantity may refer to measuring spatial and/or temporal variability –Quality may refer to absolute vs. relative concentrations (accuracy vs precision) Cost – including manpower Detection limits & contamination issues Holding times & other logistics