Mercury in Eisenia fetida and soil in the vicinity of a natural gas treatment plant in northern Croatia during the last ten years

In this study total mercury concentrations in earthworms and in different soil types at the same locations from the surroundings of four boreholes were analyzed by ICP-MS method, as a part of a comprehensive monitoring of the eco-system in the vicinity of the natural gas production and treatment plant Molve in northern Croatia. The aim of this study was to determine the concentration of mercury in the collected samples from 2009 to 2019, monitor its changes over a last ten years period and determine the bioaccumulation of total mercury in earthworms from the soil. During the last ten years total mercury concentrations in earthworms (boreholes Molve 9-12) ranged within 0.118 and 0.675µg gDW-1 depending on the location and time of sampling, while total mercury concentrations in different soil types at the same locations ranged within 0.020 and 0.515 µg Hg g-1 of soil. The calculated mercury bioaccumulation factor ranged between 0.6 and 16.9. Comparing our results with those from the previous research period and also with results published in available literature it can be concluded that investigated area near Molve belongs to low mercury contaminated region.