An application of a phytoremediation technology in Bulgaria-The Kremikovtzi Steel Works experiment

The first in‐field phytoremediation trial in Bulgaria was initiated in the summer of 1998 at two highly polluted heavy‐metal sites within the industrial region of Kremikovtzi Steel Works, near the capital town of Sofia. The experiment targeted phytoextraction of lead, according to the selection of Brassica juncea seed material and technology, generously provided by Phytotech, Inc. The metal concentrations in soil samples were measured before planting and after harvest. Leaf and stem plant samples were investigated by laser mass spectrometry in search of metal accumulation depots. The results of the one‐planting experiment show a very uneven decrease between 0 and 25.9 percent of the initial lead concentration at various sample locations. The trial, which was initially planned for three consecutive years, was unfortunately terminated in the second year because the Steel Works entered a privatization procedure. Nevertheless, the experimental data obtained confirmed the general applicability of phytoremediation to treat soil polluted with heavy metals. The experiment was further successful, because it confirmed the proposal to clean the three‐kilometer ecological zone around the Steel Works with two plantings per year in two years to levels below the maximum permissible level for lead of 25 to 80 g/t for pH 4, according to the Bulgarian Environmental Standards. © 2006 Wiley Periodicals, Inc.