Fractal Analysis and Interpretation of Temporal Patterns of TSP and PM10 Mass Concentration over Tarkwa, Ghana

Tarkwa doubles as the hub for the extractive industry in Ghana and the single district with the largest concentration of mines on the African continent. Mining activities, such as overburden removal, drilling, blasting, material excavation, hauling, ore crushing and vehicular movement continuously emit particulate matter (PM) into the atmosphere. Thus, PM pollution is of concern in the surrounding communities. This research explored the temporal variation in Total Suspended Particle (TSP) and PM10 (Particulate matter with aerodynamic diameter ≤ 10) concentration in Tarkwa from 2015 to 2019 as well as their relationship with different meteorological parameters. The study further analysed the fractal behaviour of TSP and PM10 by comparing five different Hurst estimation algorithms using data obtained from 15 communities within Tarkwa. The trend analysis revealed an exponential increase in PM10 from 2015 to 2017 with a decreasing trend from 2017 to 2019. TSP concentrations also increased from 2015 to 2018 and then dipped in 2019. TSP and PM10 data exhibited substantial seasonal variation across all the 15 monitoring sites with the highest values recorded in the dry season. TSP and PM10 concentrations positively correlated with temperature (Temp) and sunshine (SS) while inversely correlated to relative humidity (RH), rainfall (RF) and wind speed (WS). Five Hurst exponent estimation methods; namely, Rescale Range (R/S), Aggregated Variance (AV), Absolute Moments (AM), Difference Variance (DV) and Higuchi Method were employed to investigate the existence of dynamic fractal behaviour and long memory. In this study, the AM, AV and Higuchi methods produced results consistent with the observed data. The estimated TSP/PM10 Fractal Dimension (FD) values also depicted a complex multiple time scale behaviour of the data with a high degree of roughness.