Trace element profile of TSPM with depth within opencast coal mines for risk assessment and their source apportionment

This study presents source apportionment and toxicity level of trace element concentration in total suspended particulate matter (TSPM) fraction of settled dust at different benches of opencast coal mine. In opencast coal mine, various mining associated activities are responsible for emission of TSPM. It is significant to study these airborne TSPM and associated trace elements as mineworkers and surrounding environment are directly exposed to it. The order of mean concentration of trace elements shows that Pb ranked fourth at bench-2 & 4 and Cr ranked fourth at bench-3 whereas, Fe, Mn and Zn are among the top three at all benches. Whereas trace element concentration in haul road dusts are found higher than other locations. In this study, Spearman correlation and principal component analysis (PCA) is performed to observe the percentage contribution of exhaust & non-exhaust emission due to heavy earthmoving machineries (HEMMs) operation. A source apportionment indicates that possible contributing sources to the trace elements are geogenic (46.68%) > exhaust & non-exhaust emission (28.37%) > coal dust (10.24%). The trace elements associated to the TSPM add to the menace. Therefore, variability in toxicity of the TSPM (< 62 μm) fraction of dust within opencast coal mines was observed using the pollution indicators such as contamination factor, pollution load index, modified degree of contamination, geo-accumulation index and ecological risk index. The TSPM (< 62 μm) fraction of haul road dust is found more toxic in comparison to other locations at different depth.