Download - Determination of Precipitation Contamination

Determination of Precipitation Contamination

Derek AndersonTeri Wilson

Hypothesis

We believe that snow is purer than rain.

The Six Common Air Pollutants

• Ozone• Particulate Matter• Carbon Monoxide• Nitrogen Oxides• Sulfur Dioxide• Lead

Nitrogen Oxides (NOx)

• Most common are: nitrogen dioxide (NO2) and nitric oxide (NO)

• Primary sources are: kerosene heaters, un-vented gas stoves/heaters, and environmental tobacco smoke

• Causes eye, nose, and throat irritation• National Ambient Air Quality Standard for

Nitrogen Dioxide: <0.053ppm

Lead (Pb)

• A metal found naturally in the environment as well as in manufactured products

• Once taken into the body, lead distributes throughout the body in the blood and accumulates in the bones

• Lead exposure affects the oxygen carrying capacity of the blood

• National Ambient Air Quality Standard for Lead: <0.15μg/m3

Collection Method

• Samples were collected outside of Teri’s garage

• Collected in clean, dry plastic containers

• Poured into sterile glass jars and covered securely

• Stored in the refrigerator until testing

Collection of Precipitation

Sample Type of Precipitation

Date Outside Temperature

Sample 1 Freezing Rain 2-5-11 31.2 F

Sample 2 Rain 2-5-11 35.7 F

Sample 3 Snow 2-5-11 34.8 F

Sample 4 Rain 3-6-11 53.2 F

Sample 5 Rain/Snow Mix 3-30-11 42.9 F

Sample 6 Snow 3-30-11 38.8 F

Testing

• Dionex ICS-90 Ion Chromatography (IC)

• HP 8453 Diode Array UV/Vis Spectrophotometer

• Varian Inductively Coupled Plasma (ICP-OES)

IC Experiment

• Analyte of Interest– Nitrate and Nitrite

• Standards Used– 7 Anion Standard• Standard 1 – 10 ppm• Standard 2 – 15 ppm• Standard 3 – 20 ppm• Standard 4 – 25 ppm• Standard 5 – 100 ppm

IC Parameters

• Pressure: 890 psi

• Flow rate: 1 mL/min

• Pressure Gauge: Slightly above 9

IC Nitrite ResultsType Peak Height (μS)

Standard 1 10 ppm 3.433





Sample 1 Freezing Rain 6.867

Sample 2 Rain 0.465

Sample 3 Snow 0.043

Sample 4 Rain 0.052

Sample 5 Rain/Snow Mix N/A

Sample 6 Snow N/A

Nitrite Calibration Curve

Calculated Nitrite ConcentrationsSample Type Concentration (ppm)

Sample 1 Freezing Rain 24.95451Sample 2 Rain -1.2832Sample 3 Snow -3.0127Sample 4 Rain -2.97582Sample 5 Rain/Snow Mix N/ASample 6 Snow N/A

* Negative numbers denote negligible values

IC Nitrate ResultsType Peak Height (μS)






Sample 1 Freezing Rain 4.792

Sample 2 Rain 0.406

Sample 3 Snow 0.352

Sample 4 Rain 0.320

Sample 5 Rain/Snow Mix 0.472

Sample 6 Snow 0.288

Nitrate Calibration Curve

Calculated Nitrate ConcentrationsSample Type Concentration (ppm)

Sample 1 Freezing Rain 23.62385Sample 2 Rain 2.445678Sample 3 Snow 2.184935Sample 4 Rain 2.03042Sample 5 Rain/Snow Mix 2.764365Sample 6 Snow 1.875905

UV/Vis Experiment

• Analyte of Interest– Nitrate

• Standards Used– Standard 1 – 5 ppm– Standard 2 – 10 ppm– Standard 3 – 15 ppm– Standard 4 – 20 ppm– Standard 5 – 25 ppm

UV/Vis Parameters

• Mode: Standard

• Task: Fixed Wavelength– 224 nm

• Data Type: Absorbance & Second Derivative

• Path Length: 1 cm

UV/Vis Nitrate ResultsType Mean Absorbance

Standard 1 5 ppm 0.500813Standard 2 10 ppm 0.99299Standard 3 15 ppm 1.463267Standard 4 20 ppm 1.773733Standard 5 25 ppm 2.1732Sample 1 Freezing Rain 0.060441Sample 2 Rain 0.031449Sample 3 Snow 0.088468Sample 4 Rain 0.017756Sample 5 Rain/Snow Mix 0.129787Sample 6 Snow 0.050405


Calculated Nitrate ConcentrationsSample Type Concentration (ppm)

Sample 1 Freezing Rain -1.00193Sample 2 Rain -1.35334Sample 3 Snow -0.66221Sample 4 Rain -1.51933Sample 5 Rain/Snow Mix -0.16137Sample 6 Snow -1.12358

* Negative numbers denote negligible values

Results produced indicate method is not compatible and did not work for our purposes.

UV/Vis Nitrate ResultsType Second Derivative

Standard 1 5 ppm 0.002654Standard 2 10 ppm 0.004063Standard 3 15 ppm 0.001349Standard 4 20 ppm -0.00754Standard 5 25 ppm -0.02788Sample 1 Freezing Rain --Sample 2 Rain --Sample 3 Snow --Sample 4 Rain --Sample 5 Rain/Snow Mix --Sample 6 Snow --


Calculated Nitrate Concentrations

Even using the Second DerivativeMode, results indicated the method did not

work and was not compatible for our purposes.

ICP Experiment

• Analyte of Interest– Lead (II)

• Standards Used– Blank – 0 ppm– Standard 2 – 40 ppm– Standard 3 – 60 ppm– Standard 4 – 80 ppm– Standard 5 – 100 ppm

ICP Parameters

• Search for Pb(II) at:– 179.605– 182.143– 220.353

• Used Pb(II) at 220 based upon UV/Vis wavelength obtained

ICP Lead ResultsType Intensity

Blank 0 ppm 80.891Standard 2 40 ppm 152.27Standard 3 60 ppm 205.55Standard 4 80 ppm 241.31Standard 5 100 ppm 295.66Sample 1 Freezing Rain 73.989Sample 2 Rain 73.286Sample 3 Snow 75.383Sample 4 Rain 73.505Sample 5 Rain/Snow Mix 75.403Sample 6 Snow 74.098

Lead Calibration Curve

Calculated Lead ConcentrationsSample Type Concentration (ppm)

Sample 1 Freezing Rain -0.666074185Sample 2 Rain -0.994901539Sample 3 Snow -0.014032462Sample 4 Rain -0.892464568Sample 5 Rain/Snow Mix -0.004677487Sample 6 Snow -0.615089574

Discussion

• UV/Vis data did not provide results of significance

• ICP yielded negligible concentrations of lead in samples

• Overall results support Freezing Rain to contain higher levels of Nitrogen Oxides (NOx)

Troubleshooting

• Sample Nitrite values are below IC sensitivities• IC baseline is below 0.00 • UV/Vis protocol not understood

Summary

• The original hypothesis that snow is purer than rain was rejected based on our findings

• No specific precipitation type yielded more pure results than another

• Only that Freezing Rain contained significantly higher concentrations of Nitrogen Oxides

References

Evaluation of a second derivative UV/visible spectroscopy technique for nitrate and total nitrogen analysis of wastewater samples

Michelle A. Ferree and Robert D. ShannonWater Research 2001 35 (1), p. 327-332.

What Are the Six Common Air Pollutants. http://www.epa.gov/ebtpages/airairpollutants.html. 2 April 2011.