Why do we Measure Precipitation Chemistry? Christopher Lehmann CAL Director

1. Why do we Measure Precipitation Chemistry? Christopher Lehmann CAL Director 2007 Field Operations Training Course

2. REMOVAL ATMOSPHERIC TRANSPORT & TRANSFORMATION REACTIONS GAS/PARTICULATE PHASE AEROSOL PARTICLES & GASES AQUEOUS PHASE PRECIPITATION Precipitation volume/time Deposition velocity Atmospheric Deposition EMISSIONS ENVIRONMENTAL IMPACTS

3. Environmental Impacts • Stream and lake acidification • Increased fish mortality (eggs, fry)

4. U.S. EPA, 2002: Response of Surface Water Chemistry to the Clean Air Act Amendments of 1990.

5. pH effects on fish population MO03 5.0 OH49 4.3 Source: HBRF, Acid Rain Revisited, 2001

6. Environmental Impacts • Stream and lake acidification • Increased fish mortality (eggs, fry) • Damage to vegetation

7. Damage to forests Mt. Mitchell, North Carolina

8. Acid deposition effects Source: HBRF, Acid Rain Revisited, 2001

9. Environmental Impacts • Stream and lake acidification • Increased fish mortality (eggs, fry) • Damage to vegetation • Benefits certain agricultural crops (reduces fertilizer needed) • Benefits invasive species

10. Environmental Impacts • Contributes to wetland nutrient loads

11. Nitrogen Effects Nitrogen damage to aquatic systems

12. Environmental Impacts • Contributes to wetland nutrient loads • Bioaccumulates in aquatic environments (Hg)

13. Dry Deposition Wet Deposition Bacterial action (water and sediment) predatory fish The mercury problem? Bioaccumulation Geologic Sources (soil, rock, base flow etc.) Water Body Hg Hg Hg Me-Mercury Concentration Methylation Smaller fish Zooplankton

14. Environmental Impacts • Contributes to wetland nutrient loads • Bioaccumulates in aquatic environments (Hg) • Damage to buildings, structures, and statues • Corrosion of materials

15. Limestone statue of George Washington first put outside in New York City in 1944 Source: ACS, Chemistry in Context, 2006

16. The NADP • 3 Precipitation monitoring networks • National Trends Network (NTN) • Atmospheric Integrated Research Monitoring Network (AIRMoN) • Mercury Deposition Network (MDN) • 2 Analytical Laboratories • Central Analytical Laboratory, ISWS • Frontier Geosciences, Seattle, WA

17. Species Measured by the NADP • acidic species • free acidity (or pH), sulfate, nitrate, chloride • nutrients • nitrate, ammonium, orthophosphate • earth crustal base cations • calcium, magnesium, potassium • salts • sodium and chloride • heavy metals • mercury, trace metals (MDN)

18. Precipitation Acidity: pH pH is the power of hydrogen, ameasurement of the hydrogen ion concentration pH = -log10([H+], mol/L) H2Ol H+aq+ OH-aq pH 7 is NEUTRAL: [H+] = [OH-] acid base

19. Acidic Precipitation Acidic precipitation or acid rain is defined at pH < 5.0 to relfect human-induced pollution Why….. • Carbon dioxide in air • CO2,g + H2Ol = H2CO3,aq(carbonic acid) • PCO2 = 350 ppm pH ~ 5.6 • Naturally occurring acid species also reduce the pH of rain • sulfate from oceans • organic acids

20. Is “Acid Rain” still an issue?

21. Sulfate (SO42-) & Nitrate (NO3-)

22. Atmospheric Reactions: Conversion of Sulfur Dioxide to Sulfate • Sulfur dioxide conversion to sulfite: • Oxidation of sulfite to sulfate: SO2 + H2O ↔ SO2∙H2O SO2∙ H2O↔ H+ + HSO3- HSO3- ↔ H+ + SO32- SO2,g SO42-aq • One pathway by ozone: SO32- + O3 ↔ SO42-+ O2 • can also be oxidized by hydrogen peroxide, OH radicals, nitrogen oxides, formaldehyde, iron, and manganese Seinfeld and Pandis, 1998

25. 100 m 1 ha = 104 m2 1.91 milligrams of sulfate dissolved in 1 liter of water 100 m 17.2 kilograms of sulfate spread over 1 hectare in one year CONCENTRATION = Mass of pollutants per unit volume of water collected DEPOSITION=Mass of pollutant that falls on a fixed unit of area 1.91 mg/L sulfate ion Bondville, IL in 2005 (average) 17.2 kg/ha sulfate ion Bondville, IL in 2005 (total)

26. Atmospheric Reactions: Conversion of Nitrogen Dioxide to Nitrate NO2,g HNO3,g NO2 + OH∙ + M ↔ HNO3 + M HNO3 + H2O ↔ H+ + NO3- HNO3,g NO3-aq Seinfeld and Pandis, 1998

28. Ammonium (NH4+)

29. Atmospheric Reactions: Conversion of Ammonia to Ammonium NH3,g NH3+ H2O ↔ NH3∙H2O NH3∙H2O ↔ NH4+ + OH- NH4+aq Seinfeld and Pandis, 1998

32. Crustal Cations:Calcium (Ca2+), Magnesium (Mg2+) & Potassium (K+)

33. What is the role of base cations in precipitation chemistry? Base cations neutralize the affects of acidic precipitation anion sum(1) cation sum(2) pH MN = 74 88 6.31 NY = 74 22 4.34 (1) anions = sulfate, nitrate, and chloride (2) cations = ammonium, calcium, magnesium, potassium, and sodium

37. Base Cations & Sample Collection Important sampling considerations: • Please ensure that sample is WET ONLY! • Watch the event recorder tracing on the raingage • Ensure that the NTN sampler is operating properly • Note unusual events at site (burning, farm activities, construction, etc.) and record this information in the comments section of the FORF • Large dust particles dry deposit efficiently NY could look like MN due to base cation increases

40. Why Shouldn’t I use Tap Water? NADP/NTN Site in Ohio (microequivalents/liter) Cl- = 7 SO4 2- = 69 NO3- = 32 anion sum = 108(sulfate, nitrate, and chloride) cation sum = 33(ammonium, calcium, magnesium, potassium, sodium) Champaign Urbana Water (microequivalents/liter) Cl- = 234 SO4 2- = 650 NO3- = 3 anion sum = 887 cation sum = 3062 Please use only deionized water and laboratory wipes to clean the NADP collector. Do not re-wash, rise, or otherwise clean the supplies provided by the CAL unless you are instructed to do so.

44. Questions?

45. Please remember to fill out your critique as you complete each section