A radiological survey and the impact of the elevated concentrations of 210Pb and 210Po released from the iron- and steel-making plant ILVA Taranto (Italy) on the environment and the public

Abstract

A radiological survey on the iron- and steel-making plant ILVA Taranto (Italy) was mainly focused on contamination source-term investigation and exposure impact evaluation of the volatile radionuclides ²¹⁰Po and ²¹⁰Pb. The activity concentrations of ²¹⁰Po and ²¹⁰Pb in the raw materials, dust particles, surficial soils and atmospheric particulate samples collected in the area of ILVA Taranto were determined. The results showed that the activity concentrations in the raw materials were in the range of 3.46–17.9 Bq kg⁻¹ for ²¹⁰Po and 3.50–16.8 Bq kg⁻¹ for ²¹⁰Pb, which could create maximum annual inventories of 2.64 × 10¹¹ Bq of ²¹⁰Po and 2.71 × 10¹¹ Bq of ²¹⁰Pb if a total quantity of 22 Mt per year raw materials was consumed in the plant. The activity concentrations in dust particles emitted from the chimney of the ILVA Taranto were in the range of 5.91–85.6 kBq kg⁻¹ for ²¹⁰Po and 5.44–34.6 kBq kg⁻¹ for ²¹⁰Pb, releasing more ²¹⁰Po than ²¹⁰Pb. The activity concentrations in surficial soils were in the range of 49.3–140 Bq kg⁻¹ for ²¹⁰Po and 51.6–150 Bq kg⁻¹ for ²¹⁰Pb, a variation of the activity concentrations being observable with distance. The activity concentrations in atmospheric particulate were in the range of 43.1–564 μBq m⁻³ for ²¹⁰Po and 618–1099 μBq m⁻³ for ²¹⁰Pb, and it was observed that the mass specific activity concentrations of ²¹⁰Po and ²¹⁰Pb in the atmospheric particulate are one to three orders of magnitude higher than that found in the top soil. After deduction of the background contribution, about 27.2 μSv per year of the estimated committed effective dose at mean and 49.2 μSv per year at maximum could be attributed to ²¹⁰Po and ²¹⁰Pb emitted from the chimney of the ILVA Taranto and inhaled by the public in the form of atmospheric particulate, of which about 63.5–69.0% was the contribution of ²¹⁰Pb. No specific interventions should be required, as far as only inhalation of ²¹⁰Po and ²¹⁰Pb are concerned.