Chemical characterisation and health implications of atmospheric particulate matter In Ghana's mining hub of Tarkwa
摘要
It has now been established that the chemical composition of Particulate Matter (PM) is essential for predicting its associated health endpoints. This paper presents a comprehensive study of the chemical composition and associated health risk of atmospheric particulate matter in the mining city of Tarkwa, Ghana. Total suspended particles (TSP) and PM10 were monitored biweekly for one year using miniVol air samplers for three communities within Tarkwa. The exposed filter samples were divided into two parts and chemically characterised using Scanning Electron Microscope – Energy Dispersive X-ray (SEM–EDX) for elemental particle analysis, and ICP-MS for metal analysis. The risk of non-carcinogenic health impact in the exposed population was computed using the Target Hazard Quotient (THQ), while Positive Matrix Factorisation (PMF) was applied for source identification. The recorded mean TSP mass concentrations for monitoring sites Abekoase (AK), Nsuta (NV), and Tarkwa Banso (TN) were 27.74, 157, and 163 µg/m3, respectively. PM10 mean concentrations were 23.8, 70.85 and 78.64 µg/m3 for AK, NV and TN, respectively. The SEM–EDX analysis revealed particles rich in Si, Al, Na, Zn, Fe, Ca, K, F, O, Mn, and C, with varied mass percentage abundance pointing to Aluminosilicates, Aluminosilicates-soot and likely psilomelane for both TSP and PM10. Varied Metal concentrations in decreasing order of Al > Zn > Mg > Fe > Si > Mn were recorded for TN and NV, while a decreasing order of Mg > Al > Zn > Si > Fe > Mn was recorded for AK. The dry season recorded higher PM-bound metal concentration than the wet season. The metallic concentrations of Fe, Si, Mg and Zn corresponded to a THQ of below unity for both children and adults. However, the estimated THQs for Al and Mn ranged from 2.22 to 19.44 and from 2.64 to 21.78, indicating an adverse health impact on the exposed population. The major PM emission sources were identified as crustal dust, traffic sources and industrial/mining activities. This study establishes a baseline for the study area by providing critical insight into PM pollution, its sources, associated health impacts and priority areas for management intervention. Future investigations of PM chemical composition should extend beyond elemental analysis to include water-soluble fractions, mineralogical characteristics and mechanism of action, particularly in relation to human health, to achieve a more comprehensive understanding of PM properties and behaviour.