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

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

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

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

pH effects on fish population Source: HBRF, Acid Rain Revisited, 2001 OH MO03 5.0

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

Damage to forests Mt. Mitchell, North Carolina

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

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

Environmental Impacts Contributes to wetland nutrient loads

Nitrogen damage to aquatic systems Nitrogen Effects

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

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

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

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

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

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) Species Measured by the NADP

Precipitation Acidity: pH pH is the power of hydrogen, a measurement of the hydrogen ion concentration pH = -log 10 ([H + ], mol/L) H 2 O l  H + aq + OH - aq pH 7 is NEUTRAL: [H + ] = [OH - ] acidbase

Acidic Precipitation Acidic precipitation or acid rain is defined at pH < 5.0 to relfect human-induced pollution Why….. Carbon dioxide in air –CO 2,g + H 2 O l = H 2 CO 3,aq (carbonic acid) –P CO2 = 350 ppm  pH ~ 5.6 Naturally occurring acid species also reduce the pH of rain –sulfate from oceans –organic acids

Is “Acid Rain” still an issue?

Sulfate (SO 4 2- ) & Nitrate (NO 3 - )

1.Sulfur dioxide conversion to sulfite: 2.Oxidation of sulfite to sulfate: Atmospheric Reactions: Conversion of Sulfur Dioxide to Sulfate SO 2 + H 2 O ↔ SO 2 ∙ H 2 O SO 2 ∙ H 2 O ↔ H + + HSO 3 - HSO 3 - ↔ H + + SO 3 2- One pathway by ozone: SO O 3 ↔ SO O 2 can also be oxidized by hydrogen peroxide, OH radicals, nitrogen oxides, formaldehyde, iron, and manganese Seinfeld and Pandis, 1998 SO 2,g SO 4 2- aq

CONCENTRATION = Mass of pollutants per unit volume of water collected 1.91 mg/L sulfate ion Bondville, IL in 2005 (average) DEPOSITION = Mass of pollutant that falls on a fixed unit of area 17.2 kg/ha sulfate ion Bondville, IL in 2005 (total) 100 m 1 ha = 10 4 m milligrams of sulfate dissolved in 1 liter of water 17.2 kilograms of sulfate spread over 1 hectare in one year

Atmospheric Reactions: Conversion of Nitrogen Dioxide to Nitrate NO 2 + OH ∙ + M ↔ HNO 3 + M HNO 3 + H 2 O ↔ H + + NO 3 - Seinfeld and Pandis, 1998 HNO 3,g NO 3 - aq NO 2,g  HNO 3,g

Ammonium (NH 4 + )

Atmospheric Reactions: Conversion of Ammonia to Ammonium NH 3 + H 2 O ↔ NH 3 ∙H 2 O NH 3 ∙H 2 O ↔ NH OH - Seinfeld and Pandis, 1998 NH 3,g NH 4 + aq

Crustal Cations: Calcium (Ca 2+ ), Magnesium (Mg 2+ ) & Potassium (K + )

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 = NY = (1) anions = sulfate, nitrate, and chloride (2) cations = ammonium, calcium, magnesium, potassium, and sodium

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

Why Shouldn’t I use Tap Water? NADP/NTN Site in Ohio (microequivalents/liter) Cl - = 7 SO 4 2- = 69 NO 3 - = 32 anion sum = 108 (sulfate, nitrate, and chloride) cation sum = 33 (ammonium, calcium, magnesium, potassium, sodium) Champaign Urbana Water (microequivalents/liter) Cl - = 234 SO 4 2- = 650 NO 3 - = 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.

Questions?

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