sasol presentation fh stenden

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

Contact details:22702873@nwu.ac.za

THANK YOU