Spatio-temporal monitoring of mercury and other stable metal(loid)s and radionuclides in a Croatian terrestrial ecosystem around a natural gas treatment plant

The natural gas industry bears a certain contamination risk to human and biota due to, among others, mercury, arsenic, and naturally occurring radioactive material content in gas. We tracked multiple stabile metal(loid)s and radionuclides within the natural gas treatment plant Molve, Croatia, ecosystem during the last decade through a comprehensive monitoring of soil, earthworms, moss, livestock (blood, milk, hair, urine, and feces from cows), and wildlife animals (brain, muscle, liver, and kidney of European hare and pheasant). The level of mercury and other stable metal(loid)s has shown temporal variation, but without an obvious trend. The found spatial differences in soil and earthworms were based on the differing soil characteristics of the sampled locations and exceeded the maximal allowable concentration of arsenic and zinc for agricultural soil. The status of essential copper, selenium, and zinc in cows, hares, and pheasants inclined towards deficiency. The measured stable metal(loid) levels in soil and animal samples were generally in the same range of values reported in earlier decades from the same area or non-polluted areas across Europe. The consumption of local cow and game products (e.g., milk, meat) can be considered safe for human health, although game offal is advised to be avoided as a food item due to the low risk of lead and cadmium's adverse effects. Although the activity concentrations of some radionuclides in moss were higher than reported for pristine areas, transfer from soil to moss was assessed as average (except for lead-210). Radiological risk to human and biota around the gas treatment plant Molve was estimated as negligible.

Automated summary

The natural gas industry may pose a contamination risk to human and biota due to the presence of mercury, arsenic, and naturally occurring radioactive materials in gas. A comprehensive monitoring of soil, animals, and plants in the natural gas treatment plant in Molve, Croatia, revealed temporal variations in the levels of mercury and stable metal(loid)s, but without a clear trend. Spatial differences in soil and earthworms were found, exceeding the maximum allowable concentrations of arsenic and zinc in agricultural soil. There was a deficiency of essential copper, selenium, and zinc in cows, hares, and pheasants. The consumption of local cow and game products was considered safe, except for game offal due to the low risk of lead and cadmium's adverse effects. Radiological risk around the gas treatment plant was estimated as negligible.