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MDN Network Operations – HAL Sample Evaporation Study

This study examines the evaporation phenomena associated with MDN ACM samples, focusing on the effects of fan operation during evaporation. Conducted between October 2012 and February 2013, the research analyzed 40 collocated samples, comparing conditions with the fan on versus off. Results showed minimal variation in sample loss, with average losses of 20.8 mL (fan on) and 19.5 mL (fan off). Additionally, there was no significant loss of mercury concentration across conditions. Future studies will explore lower spiked sample volumes to further assess evaporation tendencies.

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MDN Network Operations – HAL Sample Evaporation Study

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  1. MDN Network Operations – HAL Sample Evaporation Study • Follow up study from PO report (Spring/Fall 2012) • PO Data Show MDN ACM Evap With Fan On • Phenomena associated with MDN ACM only Data Courtesy – Mark Rhodes PO

  2. MDN Network Operations – HAL Sample Evaporation Study • HAL Follow up study from PO (Spring/Fall 2012) • Examine If Capillary Tube The Issue or Fan • HAL 4 Month Study Performed Using 2 ACM • October 2012 - Feb 2013 (Collocated MDN ACMs) • 1 MDN ACM Fan Off • 1 MDN ACM Fan On • 200mL NIST Traceable Spiked (22ng Hg/L) • 400mL Spiked Samples (19ng Hg/Liter) • Collector Lid Immobilized

  3. HAL Evaporation StudyHAL Study SiteNOAA Sand Point, Washington (WA18) MDN ACM #1 MDN ACM #3 • Rotated Weekly MDN ACM Fan Off Vs On • 16+ week Study (Oct 2012 – Feb 2013 • 40 Collocated Samples Collected • Sensors Disabled – Spiked Samples Loaded For 7 Days • ~20 Samples = 200mL Spiked @ 22 ng Hg/Liter • ~20 Samples = 400mL Spiked @ 19 ng Hg/Liter

  4. MDN ACM - HAL Evaporation StudyVolume (mL) Loss Per Sample Bottle Ave Loss Fan On = 20.8 mL (+/- 3.5 mL) Ave Loss Fan Off = 19.5 mL (+/- 1.2 mL) 200 mL Samples 500 mL Samples mL Sample Loss

  5. MDN ACM - HAL Evaporation StudyVolume (mL) Loss Per Sample Bottle Ave Actual Con = 20.8 mL (+/- 3.5 mL) Ave Loss Fan Off = 19.5 mL (+/- 1.2 mL) 200 mL 500 mL Samples mL Sample Loss

  6. MDN Network Operations – HAL Sample Evaporation Study

  7. HAL Sample Evaporation StudyFan On – Actual vs Measured Spike Recovery 200 mL 500 mL Samples

  8. HAL Sample Evaporation StudyFan Off – Actual vs Measured Spike Recovery 200 mL 500 mL Samples

  9. % Recovery Of NIST Traceable Spike(Measured/Actual Spike Concentration) Ave % Recovery Fan On = 96.71% (+/- 4.1%) Ave % Recovery Fan Off = 97.20 % (+/- 3.6%)

  10. % Recovery Of NIST Traceable Spike(Measured/Actual Spike Concentration) Ave % Recovery Fan On = 96.71% (+/- 4.1%) Ave % Recovery Fan Off = 97.20 % (+/- 3.6%) 200 mLVol 500 mLVol

  11. MDN Network Operations – HAL Sample Evaporation Study • Initial Results Do Not Point To Excessive Evaporation or Evaporation Associated With Cooling Fan Running In MDN ACM • Measured Same Evaporative Loss Volume Regardless Of Original Sample Volume and Fan Operation • Results Indicate Despite Small Evap Loss No Loss Of Mercury Or Increased Hg Concentration Was Observed • Next Steps: • Lower Spiked Sample Volume Study (50mL, 100mL) • Modified MDN ACM Thistle Tube Study

  12. MDN HAL Capillary Tubes Picture: Courtesy Mark Rhodes HAL Prototype NCON MDN ACM

  13. PO Evaporation Study (2012)

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