Physicochemical properties of PM2.5 emanating from gold mine tailings in the community of eMbalenhle, South Africa

Abstract

Background: Gold mining is a significant contributor to South Africa's economy, but it also poses environmental and health risks, particularly from particulate matter (PM) emissions. Fine particulate matter (PM2.5) from gold mine tailings can be dispersed by wind, reaching nearby communities like eMbalenhle. Due to the particle size and potential toxic composition, PM2.5 is capable of penetrating deep into the lungs and entering the bloodstream, increasing the risk of respiratory and cardiovascular diseases. This study investigates the physicochemical properties of PM2.5 near the Evander gold mine tailings and the adjacent community of eMbalenhle, assessing seasonal variations in PM2.5 concentrations and elemental composition to evaluate potential environmental and health impacts. Aim: This research aims to assess and compare the physicochemical properties of PM2.5 from gold mine tailings at Evander with those observed in the eMbalenhle community. By analysing seasonal patterns, pollutant dispersion, and soil contamination, the study seeks to determine the extent to which PM2.5 properties at the source and receptor locations align, addressing both environmental quality and health risk implications. Methods: Soil and air samples were collected from two sites being Evander (source) and eMbalenhle (receptor). PM2.5 levels were monitored using Clarity Node-S monitors, while soil samples were analyzed for elemental composition using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) and X-ray fluorescence (XRF). Seasonal variations in PM2.5 concentrations were statistically assessed with one-way ANOVA to determine the variance between source and receptor sites. Soil samples were screened against Soil Screening Values (SSV) to evaluate contaminant levels and potential health risks associated with elements like arsenic, lead, chromium, and manganese. Results: The results indicate that PM₂.₅ concentrations fluctuate seasonally, with winter recording the v highest levels at both Evander and eMbalenhle due to meteorological factors such as temperature inversions. Statistical analysis revealed no significant differences (p > 0.05) in most seasonal comparisons, suggesting that while concentrations vary, they do not differ substantially between the two sites. However, the recorded PM₂.₅ levels exceed the WHO annual (5 μg/m³) and 24-hour (15 μg/m³) limits, as well as the South African NAAQS 24-hour standard (40 μg/m³), particularly in eMbalenhle during winter. Elemental analysis confirmed the presence of trace metals associated with mining activities, indicating some contribution from the Evander tailings, though additional sources such as domestic fuel combustion and industrial emissions likely influence air quality at the receptor site. Conclusion: The study assessed the seasonal variations and physicochemical properties of PM₂.₅ concentrations at the source (Evander gold mine tailings) and the receptor site (eMbalenhle). Findings indicate that while PM₂.₅ emissions from the mine tailings contribute to air pollution, seasonal variations are largely influenced by meteorological conditions and local emissions at eMbalenhle, particularly during winter when temperature inversions trap pollutants. Statistical analysis showed no significant differences (p > 0.05) in most seasonal comparisons, leading to a failure to reject the null hypothesis, suggesting that PM₂.₅ levels at the receptor site are not significantly different from those at the source. However, exceedances of WHO and NAAQS air quality standards highlight potential health risks, emphasizing the need for targeted air quality management strategies to mitigate exposure in mining-affected communities.