Determination of the occurrence of toxic trace metals at two sites in the North West Province using size of atmospheric aerosols

Abstract

The concentration levels of atmospheric aerosols of different sizes of particulate matter namely PM 10, PM 2.5, PM 1 and PM <1 were determined in the North West province mining towns of Rustenburg which is a platinum mining town, and Klerksdorp which is a gold mining town. In addition, the presence of the toxic metals lead, chromium, vanadium and nickel in the different particle sizes were determined. At the Rustenburg study site, aerosol data was collected at three hourly intervals on weekdays and weekends during the day. At night time, the data was collected over a period of twelve hours from 18h00 to 06h00 the following morning. At the Klerksdorp site the average sampling time was three hours from 09h00 to 15h00. In addition to aerosol data, meteorological data was also collected continuously and recorded at 3 hourly intervals at the two sites. The determination of the particle size concentration was made using a three stage Dekati PM 10 cascade impactor connected to a pump system which was set to give a flow rate of 30 L/min. The aerosols were collected onto polycarbonate foil filters which had been greased with an Apiezon-toulene mixture and weighed on a Sartorius Analytic A 2005 electronic balance. The chemical analysis of the samples to determine the presence of the toxic elements was done with an FEI Quanta 200 FEG scanning electron microscope.