determination of precipitation contamination derek anderson teri wilson
TRANSCRIPT
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
Standard 2 15 ppm 4.497
Standard 3 20 ppm 4.907
Standard 4 25 ppm 7.354
Standard 5 100 ppm 25.178
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)
Standard 1 10 ppm 2.308
Standard 2 15 ppm 3.024
Standard 3 20 ppm 3.552
Standard 4 25 ppm 5.177
Standard 5 100 ppm 20.651
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
Nitrate Calibration Curve
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 --
Nitrate Calibration Curve
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.