Mercury Monitoring

1. Mercury Monitoring The FDEP Laboratory Perspective Timothy W. Fitzpatrick (850) 245-8083 timothy.fitzpatrick@dep.state.fl.us

2. Considerations:Compliance versus Environmental Monitoring • Sample Kit Preparation • Sampling Protocols • Laboratory Design • Analytical Rigor • Data Interpretation

3. FDEP’s Experience • Constructed Class 1000/100 in mid-1990s; • Adopted Method 1631 w/ some modifications from initial EPA version (semi-automated the method, investigated aqua regia digestion); • Developed fully automated methylmercury analysis in late 1990s using direct ethylation P&T GCAF; • EPA incorporated semi-automated advances in Method 1631E; Automation of Draft Method 1630 under evaluation by EPA Region IV;

4. FDEP’s Experience • Primary Client Focus: Environmental Monitoring and Research • Detection Limits: THg ~ 100 pg/L (0.10 ng/L) MeHg ~ 20 pg/L (0.02 ng/L) • Initiated Everglades Mercury Round Robins ca. 2000

5. Introduction to Method 1669 • “Clean hands/dirty hands” sampling • Ultra-trace detection levels and methods • Tables listing applicable levels in sampling methods • “Mindset” and technique • Protection of sample against contamination

6. Sampling Kits • Double Bagged, Pre-Cleaned Vessels of Glass, Teflon or Surface Fluorinated P-E Prepared in Laboratory • Prices: Glass < Fluor. PE <<< Teflon • Pre-Cleaned Sampling Equipment May Be Needed (Teflon Tubing, Silicon Pump Tubing, Filtration Devices, etc.) • Laboratories are Sources of Contamination! (Air, DI Water, Reagents, etc.) • Clean Benches or Clean Room Strongly Recommended for Equip. Preparation (Absolute Necessity for Environ. Monitoring)

7. Sampling by Method 1669 • Performance Based Method • Compliance vs. Environmental Monitoring: When is the Full-Blown Method Necessary (or Practical)? • Our Experience w/ Hg – Most Contamination Occurs in the Laboratory • Vessels Need to be Prepared in a ‘Clean’ Laboratory Environment

8. Sample Collection SOP • DEP SOP FS 8200 • http://www.dep.state.fl.us/labs/qa/sops.htm • Adapted from EPA 1669 • “Performance-based” concept • Verify performance with blanks & other QC • Sampling team practice recommended

9. Field Contamination Issues • Source of analyte-free water for field blanks and equipment blanks • Sampling equipment and sample containers • Sampling personnel and clothing • Ambient sampling environment • Sampling techniques

10. Sampling Equipment Decontamination • Minimum amount of pre-cleaned equipment (only) recommended ; • Controlled environment for cleaning; • See FS 8200 cleaning procedures; • Specific cleaning procedure for mercury; • All pre-cleaned items wrapped for field use; • Field-based cleaning not recommended; • Dippers not recommended; Collect directly into sample bottles where possible;

11. On-site Precautions • All equipment and supplies in covered storage until use • Keep hands and equipment away from contamination sources • Adhere to “clean hands/dirty hands” protocols • Change gloves when needed • Collect least contaminated source first Develop a ‘contamination sensitive’ mindset

12. Precautions for Sampling Equipment & Protective Clothing • Caution advised with pigmented materials, bottle labels, ink • See FS 8200 for recommended sampling equipment and materials to avoid • Wrap cleaned pump tubing ends • Don’t contaminate tubing with pump or extension device

13. Sample Preservation & Transport • Add HCl preservative upon return to lab • Max of 48 hours on ice prior to preservative • Protect bagged samples from contamination during transport and storage • Isolate or segregate samples as needed

14. 1669/245.1 - Conventional Preparation @ SFWMD; Analysis using pre-concentration CVAAS; MDL = 50 ng/L

15. Laboratory Design Considerations: Clean Bench vs. Clean Lab • Cost vs. Type of Work Envisioned • Workload Issues Sampling Bottle and Equipment Preparation Sample Preparation and Determinative Steps • Fugitive Vapor Control • Particulate Control • Instrument Location Without proper controls, spurious laboratory contamination can exceed water quality standards!

17. Instrument Schematic

19. Blanks in 1631 • Blanks play a critical role in monitoring contamination, and quantifying the mercury content of samples • Mercury levels in (digested) method blanks may be higher than those present in ambient samples • Even the best de-ionized water has measurable concentrations of mercury • Digested blanks have Hg concentrations between 0.2 and 0.6 ng/L

20. Blanks in 1631E • Confounding of mercury levels in the reagent and the de-ionized water – cannot easily separate mercury content of reagents from mercury in de-ionized water • Assumption: Most of the “background contamination” in method blanks is from the reagents and not from the DI water • No “bubbler blanks” used in the automated method

21. Quantification in 1631E • Analyze 5 method blanks and calculate the blank correction • Subtract this “blank correction term” from all samples

22. Sensitivity Requirements Natural Waters Typical Levels: 0.5 – 2 ng/L THg < 0.02 – 0.2 ng/L MeHg Recommended Quantitation Limits: ~ 0.5 ng/L THg ~0.05 ng/L MeHg Discharge Monitoring Water Quality Standards: 12 ng/L THg Fresh 25 ng/L THg Marine Recommended Quantitation Limits: < 10 ng/L THg Fresh < 25 ng/L THg Marine

23. Data InterpretationDetection and Quantitation Detection Limit and Quantitation Limits are Influenced by: • Sampling vessels, collection and handling techniques • Quality of the laboratory environment – particulate content of laboratory air • Cleanliness of digestion reagents and procedure • Instrumental technique

24. Data InterpretationRecommendations • Conduct on-going, long-term detection limit studies rather than one-time studies; • Confirm all water quality exceedances with a separate analysis; • Use multiple method blanks with each analytical preparation batch; • Use rigorous quality control measures to ensure data integrity;