Pollution index of soils along and against the wind direction within a 40 km distance of Morupule Fly Ash Dumpsite, Botswana

Abstract

AbstractArsenic, chromium, copper, lead, and zinc concentrations were measured in the leeward and windward directions within 40 km of the Morupule power station to assess the long‐term effects of fly ash deposition on the hazardous metal contamination of soils. Based on the quantities of these metals in the soil, the contamination factor, pollution load index, and potential ecological risk index were calculated to determine the potential of these metals will harm the ecosystem and human health. The results showed that areas (0.1–2 km) nearer to the dumpsite, especially in the leeward direction had higher contamination factors, 3.08–3.51 for Cr, 4.28–5.18 for Cu, and 3.10–3.17 for Pb. On the same distance, along the windward direction, the average contamination factor was 1.17× for Cr, 1.31× for Cu, and 1.7×x for Pb, less than that of the leeward direction. On the other hand, the potential ecological risk index was low for all the toxic metals being less than 40 index value independent of the wind direction. Similarly, the comprehensive ecological risk of various toxic metals indicated that the study area had a low ecological exposure as the index value was below 150. Overall, the toxic metal contamination in the soil due to the contamination factor is moderately polluted to unpolluted, especially on the leeward side, and the ecological risk of contamination is low across the study area, but continuous deposition of fly ash without proper management will increase the ecological risk.