Mercury accumulation in plants from contaminated arable lands in Eastern Slovakia

Contamination of soil by mercury poses several risks to human health through consumption of fruits and vegetables. In Slovakia, a high concentration of mercury is found in the soil of the Central Spiš region. The objective of the study is to measure the mercury concentrations in the parts of selected plant species and trees growing within 100 meters of a former ore processing facility.

A total of 24 samples of plants, 20 samples of parts of needle-leaved trees and 9 samples of parts of broad-leaved trees were collected from soils with a high concentration of mercury. The concentration was measured by atomic absorption spectrometry in different parts of the plants: leaves - 18 species, roots - 15 species, stems - 11 species, flowers - 7 species), and different parts of trees (crust - 8 species, branches - 8 species, needles - 5 species, cones - 5 species, leaves - 3 species).

The concentrations of mercury in the soils taken at a depth of 0.25 m exceeded the maximum allowed levels more than 50-times. Potatoes, parsley and carrots from these soils exceeded the maximum allowed mercury levels 6-times, 5-times and twice, respectively. The average concentrations of mercury in the roots of 2-year onions exceeded the limit more than 50-times. The flowers of cornflower contain 18.20 mg*kg ^-1 , leaves of dandelion 10.61 mg*kg ^-1 and roots of plantain 6.80 mg*kg ^-1 of mercury. Regarding trees, the highest concentrations were found in the branches of juniper and leaves of aspen - more than 1 mg*kg ^-1.

The systematic monitoring of mercury is still very important, since it was found that the end of ore processing does not solve the issue of contamination in the Central Spiš region. Therefore, the consumption of fruits and vegetables from the areas of former ore processing facilities is not recommended.