Assessment of soil contamination by 210Po and 210Pb around heavy oil and natural gas fired power plants

•Fly ash containing 210Po and 210Pb is the main enhancement factor in surface soil.•210Pb and 210Po in soil are higher inside the campus area than the surrounding areas.•210Pb and 210Po in ash along the combustion path varied with compartment temperature.•Fly-ash contains 210Pb and 210Po much higher than bottom-ash.

Soil contamination by 210Pb and 210Po around heavy oil and natural gas power plants has been investigated; fly and bottom ash containing enhanced levels of 210Pb and 210Po were found to be the main source of surface soil contamination. The results showed that 210Pb and 210Po in fly-ash (economizer, superheater) is highly enriched with 210Pb and 210Po, while bottom-ash (boiler) is depleted. The highest 210Pb and 210Po activity concentrations were found to be in economizer ash, whereas the lowest activity concentration was in the recirculator ash. On the other hand, 210Pb and 210Po activity concentrations in soil samples were found to be higher inside the plant site area than those samples collected from surrounding areas. The highest levels were found in the vicinity of Mhardeh and Tishreen power plants; both plants are operated by heavy oil and natural fuels, while the lowest values were found to be in those samples collected from Nasrieh power plant, which is only operated by one type of fuel, viz. natural gas. In addition, the levels of surface soil contamination have decreased as the distance from the power plant site center increased.