STUDY OF TROPOSPHERE
How lasers will point to the extent of pollution in industrial skies
Scientists will shine a powerful new laser spotlight into the sky above one of SA’s largest industrial cities to get a clearer picture about air pollution, weather and the potential for human-induced climatic change — up to 15km above ground level.
Equipped with a new R2.5m atmospheric laser radar system, researchers from the University of Zululand (Unizulu) hope to gather new data on aerosol particles, chemicals, water vapour and ice crystals in the troposphere above Richards Bay and the neighbouring uMhlathuze region.
The city, once a small fishing village, was transformed in the 1970s when a new deep-water harbour and coal terminal were built, along with several major industries to process paper, heavy minerals, fertilisers, aluminium, woodchips and other goods. Major industries in the region include Mondi, Sappi, Richards Bay Minerals, South32 and Foskor.
The instrument to be used to monitor air quality and atmospheric conditions high above Richards Bay is a light detection and ranging (LiDAR) system, which can emit thousands of laser pulses per second to build up a "map" of clouds, moisture and other almost invisible particles.
Similar laser technology is used by traffic police for vehicle speed trapping, while Nasa astronomers and physicists have used laser pulses to record snow particles falling in the atmosphere of Mars.
The new mobile LiDAR laboratory is housed in a converted shipping container at Unizulu for a series of research projects led by Nkanyiso Mbatha, in collaboration with Prof Sivakumar Venkataraman from the University of KwaZulu-Natal physics department. Mbatha says the uMhlathuze area is a region of high industrial activity, which could lead to changes in local air quality and other environmental issues, so the new mobile equipment at Unizulu could assist the local municipality to monitor air quality in the region.
During previous studies on atmospheric aerosols in Mpumalanga, Venkataraman noted that SA is one of the biggest sources of human-generated aerosols in the region, yet there is a lack of data on the effects of a wide variety of aerosols in regional climatology studies.
Further afield, researchers at Princeton University in the US reported in 2011 that they had found "compelling evidence" that human-influenced aerosol emissions shaped climate change over parts of Southern Asia, including lower rainfall.
The new laser system installed near Richards Bay was designed and built by the Council of Scientific and Industrial Research (CSIR) as part of the council’s National Laser Centre "rental pool programme", which provides laser equipment and technical support to local universities.
Funded by the Department of Science and Technology, the programme also supports research projects by training masters and PhD students.
Due to their short lifetime and strong interactions, global aerosol concentrations and properties are poorly known. For these reasons, information on the large-scale three-dimensional aerosol distribution in the atmosphere should be continuously monitored
Hardus Greyling, national programmes manager for the CSIR National Laser Centre said: "Having a ground-based LiDAR system in Richards Bay will contribute to an already existing network of LiDAR systems and will be used to specifically study the atmosphere above Richards Bay, which could be negatively affected by industrial activity in the region."
An air specialist report published by the KwaZulu-Natal provincial government in 2004 notes that while many greenhouse gases occur naturally, man-made emissions of these gases are also believed to influence the mixing ratios of atmospheric gases and could therefore contribute to an "enhanced" greenhouse gas effect, commonly referred to as global warming.
The report notes that the increasing global volume of human-induced emissions of carbon dioxide is of particular concern. "Air in the atmosphere typically comprises 79% nitrogen, 20% oxygen and a 1% mixture of carbon dioxide, water vapour and small quantities of other gases. This ratio is affected by air pollutants released from a number of anthropogenic activities, and the status of human well-being is directly dependent on the status of air quality."
The Richards Bay Clean Air Association, predominantly funded by local industries, was set up in the mid-1990s following increasing complaints about air pollution by local residents, including several gas leaks from the Foskor fertiliser factory, which led to the temporary evacuation of the central business district and scores of people being sent to hospital for observation.
However, this association only monitors a limited range of air pollutants, including sulphur dioxide, fine-grained particulate matter and odorous sulphides at ground level. While the association’s website contains current data on these pollutants, the last available annual report was published in 2012.
In Europe, several research groups have been collaborating since 2000 as members of the European Aerosol Research Lidar Network, or EARLINET. Network members have established a network of 31 LiDAR stations across Europe to gain a better understanding of the influence of atmospheric aerosols on climate change, human health and environment.
"Due to their short lifetime and strong interactions, global aerosol concentrations and properties are poorly known. For these reasons, information on the large-scale three-dimensional aerosol distribution in the atmosphere should be continuously monitored," the network says.