Assessing fine particulate matter (PM2.5) concentrations at a gold mine tailing facility and adjacent community

Abstract

South Africa is home to some of the world’s largest gold mines and contributes significantly to global gold production. However, gold mining activities generate waste in the form of soil, which is stored at Tailing Storage Facilities (TSFs). Gold mine TSFs are a source of ambient PM_2.5. PM_2.5 is particulate matter with a diameter of 2.5 micrometres or smaller. While many studies have documented the diurnal and seasonal variations of ambient PM_2.5, limited studies have reported these variations at the source and receptor. This study aimed to assess the variations in PM_2.5 at the source (Evander Gold Mine TSF) and at the receptor (eMbalenhle community). Ambient PM_2.5 concentrations were monitored over a one-year period (07 February 2022 to 07 February 2023) using Clarity Node-S Low-Cost Monitors (LCMs). Meteorological data (wind speed, wind direction, solar radiation, atmospheric radiation, rain, relative humidity, and temperature) for the same period were sourced from the South African Air Quality Information System (SAAQIS). Statistical analyses were performed using the Openair packages in R Studio (version 4.0.2) and Stata software (version 18). The results showed that PM_2.5 concentrations were higher in winter and lower in summer at the community site and gold mine TSF. The average 24-hour PM_2.5 concentrations at the community site and gold mine TSF were 19.24 and 9.70 µg/m³, respectively. The daily PM_2.5 concentrations at the community site exceeded the South African National Ambient Air Quality Standard (NAAQS) of 40 µg/m³ 26 times and the WHO guidelines of 15 µg/m³ 181 times. The daily (24-hour) NAAQS was not exceeded at the gold mine TSF; however, the WHO guideline was exceeded 85 times. Diurnal PM_2.5 variations in the community showed a bimodal pattern, with peak concentrations occurring early in the morning (05:00) and late afternoon (16:00). Although the higher PM_2.5 concentrations were recorded in the community compared to the gold mine TSF, local PM_2.5 sources may have contributed to the elevated concentrations. It's recommended that future studies focus on the dispersion and source apportionment of PM_2.5 to quantify the contribution of various sources in eMbalenhle.