sasol presentation fh stenden
TRANSCRIPT
Franske StendenDr. P.G. van ZylProf. J.P. Beukes
SASOL presentation, 14 March 2016North-West University, Potchefstroom
Evaluation of SO2 and NO2 deposition & deposition velocities
Content
1. Introduction
2. Deposition studies in South Africa
3. Quantum Cascade Laser (QCL)
4. Deposition velocities calculations
5. Results
6. Specific objectives
Introduction & Background
• South Africa – more focus on economic growth and less on environmental studies
• Air quality research NB
• Anthropogenic pollutant sources common in SA
• SA one of largest industrialised economies
• SO2 & NO2 - enter atmosphere through anthropogenic & natural sources
Introduction & Background
• SO2 & NO2: Transformed (atmosphere) through chemical reactions Removed through deposition (dry / wet)
• Deposition – reactive S & N enter water, soil & vegetation
• Negative impact on environment (N – could be a nutrient, while S is also a herbicide)
Introduction & Background
N and S deposition:
• Measurements = NB
• Understanding of magnitude, spatial and temporal patterns
• Understanding of impacts
Deposition studies in South Africa
• Derived from passive sampling Eg. Josipovic et al., 2011; Collet et al., 2010; Martins 2008
• Calculated from inferential model:F (Dry deposition) =-Vd (Deposition velocity) x C (Atmospheric concentration)
Deposition studies in South Africa
• Inferential model:F (Dry deposition) = -Vd (Deposition velocity) x C (Atmospheric concentration)
• Constant deposition velocity assumed for inferential model
• Not Accurate (does reflect variability, e.g. different temporal scales) and is an assumption based on land use categories (Zhang et al., 2003)
Quantum Cascade Laser (QCL)
• Acquired QCL instrument from Aerodyne Research Inc.
• Funded by university: R 3 000 000
• Direct measurement of SO2 & NO2 concentration & flux
• Installation not funded
• SASOL funding used - Mark Zahniser from Aerodyne (installation) and supplement of MSc bursary during year 1 of MSc.
Deposition velocity calculations
• Measured values from QCL used to calculate deposition velocities
• Deposition velocity: (SO2)(Vd) = SO2 flux/SO2 avg concentration (=w'SO2'//avg (SO2) [ppm]
• Compare calculated values with literature values (Zhang et al (2003)).
Deposition velocity calculations
Passive sampling vs. QCL:
• Deposition calculated from passive sampling (Fixed deposition velocity)
• Compared with QCL (calculated deposition velocities)
Results
• At present – cleaning the data
• Data – middle February 2016
• Preliminary result of NO2 deposition velocities from 10 - 20 March, 2015
Results
Specific objectives
Specific objectives of this study include:
• Determine SO2 and NO2 deposition velocities from QCL data
• Compare with fixed ranges in literature :
Inferential method specific land use categories (Zhang et al (2003)).
Specific objectives
Specific objectives of this study include:
• Explore the temporal patterns: Seasonal and diurnal patters For diurnal give average and separate for each season
• Measuring SO2 & NO2 deposition from passive sampling
• A comparison of the deposition values from the two methods
