Distribution, speciation, mobility and ecological risk of potentially toxic elements in dust and PM2.5 from abandoned mining areas.

Environmental context: Dust is a heterogeneous material deposited on the ground surface and is a source and sink for potentially toxic elements (PTEs) originating from the air and soil. Tracking the distribution and effects of PTEs in an abandoned mining area is critical as few studies have quantified the speciation and bioavailability of PTEs contained in dust and PM_2.5. In this paper, we track the distribution of PTEs in an abandoned mining area, quantifying the mobility of PTEs using the speciation of PTEs in dust and PM_2.5 and quantitatively assess the environmental and ecological risks of PTE in a mining area. Rationale: This study aimed to gain a better understanding of the distribution, speciation, mobility and ecological risks of potentially toxic elements (PTEs) in an abandoned mining area by measuring the PTEs in dust (indoor or atmospheric) and particulate matter <2.5 μm (PM_2.5) simultaneously. Methodology: The particle size of dust, PTEs and the speciation of PTEs in dust and PM_2.5 were determined. The risk assessment code (RAC) was used to analyse the mobility of PTEs, and the geo-accumulation index (I _geo), pollution load index (PLI) and potential ecological risk index (RI) were used to assess the ecological risks of PTEs. Results: The results showed that the particle size of dust was mainly distributed in the range of 0–2.5 µm (61–81%). Cd, Mn, Cu and Zn in dust were mainly distributed in the acid extractable fraction, whereas other PTEs were distributed in the residual fraction. Most PTEs in PM_2.5 were distributed in the acid extractable fraction, but V and As were distributed in the reducible fraction. The risk of Cd, Zn and Mn in dust and PM_2.5 was very high (RAC > 50%). I _geo values showed that the dust were practically uncontaminated by most of the PTEs, whereas the PM_2.5 was moderately to highly contaminated by most of the PTEs. The PTE in dust and PM_2.5 with the highest ecological risk was Cd (E _i  >  320). The PLI showed a potential deterioration in environmental quality (1.30 < PLI < 3.17) and the further away from the mining centre, the less environmental degradation. Discussion: There is a potential for PTEs contamination and a high ecological risk in abandoned mining areas, which deserves serious attention. Environmental context. Dust is a heterogeneous material deposited on the ground surface and is a source and sink for potentially toxic elements (PTEs) originating from the air and soil. Tracking the distribution and effects of PTEs in an abandoned mining area is critical as few studies have quantified the speciation and bioavailability of PTEs contained in dust and PM_2.5. In this paper, we track the distribution of PTEs in an abandoned mining area, quantifying the mobility of PTEs using the speciation of PTEs in dust and PM_2.5 and quantitatively assess the environmental and ecological risks of PTE in a mining area. [ABSTRACT FROM AUTHOR]