The aim of this study was to test the new sampling medum – earthworm casts in a highly contaminated area. The investigation was carried out at the ancient Hg ore roasting site Pšenk in the surroundings of Idrija, where extremely high Hg contents in soils and SOM were determined in previous investigations. 32 earthworm cast samples were collected in the research grid 30 x 30 m in order to compare the Hg contents and spatial distribution in earthworm casts to the values and distributions in SOM and soil (0–15 cm). Extremely elevated Hg concentrations were determined in earthworm casts from the studied area ranging from 5.4 to 4,330 mg/kg with the median of 31 mg/kg. The Hg values in casts are somewhat lower than in soil (6.3–8,600 mg/kg) and slightly higher compared to soil organic matter (SOM) (1.5–4,200 mg/kg). Strong correlation (r²=0.75) between Hg contents in casts and soil was found, while correlation between casts and SOM was positive but weaker (r²=0.35). Spatial distribution of Hg in earthworm casts shows the highest concentrations in the central part of investigated area, similar to the distribution in soil. Hg contents rapidly decrease from the centre towards the margins of the studied area, where they reach values of less than 50 mg/kg. It was shown that Hg contents and dispersion in casts are comparable to those in soil, which indicates that at investigated area soil contamination is strongly reflected in contamination of earthworm casts
COBISS.SI-ID: 2030933
About 19 million tons of Pb-Zn ore were excavated and processed during more than 300 years of mining and metallurgical activities in the Meža Valley, leaving behind huge amounts of mine and ore processing wastes, which were deposited in abandoned mine shafts, in narrow valleys and on steep slopes of small streams at over 30 locations along the upper Meža Valley. After the closure of mine and processing facilities, dumps of poor ore and processing wastes persisted as indirect source of potentially toxic elements in the environment. The results of previous investigations of stream sediments of the Meža River and its tributaries showed high contents of Pb, Zn, As, Cd and Mo and ore minerals in tributary sediments draining large waste deposits, such as the Štopar waste deposit, the Žerjav and Kavšak waste deposits and the Fridrih waste deposit. Detailed chemical and SEM/EDS analyses of the Štopar, Kavšak and Fridrih waste deposits material were carried out with the purpose of determining the influence of waste deposits on high contents of potentially toxic elements in environmental media, determining forms of occurrence of metals in waste deposit material and assessing the stability and availability of potentially toxic elements on basis of solubility data of metal-bearing phases and minerals. Chemical analysis showed the highest contents of Pb, Zn and Cd in the Štopar waste deposit and highest contents of Mo, V and As in material of the Fridrih waste deposit. SEM/EDS analysis revealed that Pb, Zn, V and Mo in the waste deposits material mostly occur as primary ore minerals, such as cerussite, sphalerite, smithsonite, descloizite and wulfenite. A considerable amount of Pb and Zn was found bound to secondary weathering products, such as Fe-oxy-hydroxides, Mn-oxides, Fe-oxy-hydroxy sulphates and Al-silicates. Solubility of primary ore minerals is generally restricted to the pyrite weathering zones, consequently they are relatively stable in the carbonate environment of waste deposits. Secondary weathering products are also very stable and thus represent sustainable trapping and stabilisation media for Pb and Zn in investigated mine waste deposits.
COBISS.SI-ID: 1963605
Presented investigations confirmed that soils in the wider Idrija surroundings are highly enriched with mercury. The most important sources of mercury in soils for wider Idrija area were atmospheric emissions from the roasting plant. Hg gasses and dust particles have spread far into the Idrija environs. Mercury is therefore present in soils at localities far from the outcrops of ore-rich rocks. Some other small but extremely contaminated areas were identified in the woods of the Idrija environs, where ore roasting was performed in the 16th and 17th century. In the Idrija urban area there are mutual mercury impacts on the environment from the atmosphere and the soil parent material. Mercury-rich parent material in the city of Idrija is the bedrock of Pront-area, where ore-bearing rocks containing native mercury and cinnabar crop out. Additionally, mercury is present in soils developed on ore and roasting wastes dumped along the banks of the Idrijca River in the city area. In the lower Idrijca Valley the floodplain soils are contaminated with Hg because most roasted ore residues were dumped into the Idrijca riverbed and washed away because of the torrential nature of the Idrijca River and some of this mercury enriched material was deposited on the floodplains.
COBISS.SI-ID: 2101077
Five centuries of mining and processing of mercury ore in the Idrija area have resulted in widespread contamination of different environmental compartments. Environmental impacts on a regional and local scale, caused by atmospheric emissions from the Idrija ore roasting plant, were established in investigations of mercury spatial distribution in soil and attic dust in 160 km2 area. Very high values were determined in the Idrijca River valley and they decrease exponentially with the distance from Idrija. Mercury concentrations in attic dust are higher than in surrounding soils and the attic dust/soil ratio changes with distance. Measurements of mercury in the air confirmed widespread dispersion of mercury and showed highly elevated mercury concentrations around roasting plant and mine ventilation shaft. Besides, systematic monitoring of mercury contents in the stream sediments have demonstrated that huge amounts of mercury are stored in areas where ancient overbank sediments were deposited and there was no decrease in mercury concentration in active sediments during the last 15 years. Recently, interesting and extremly polluted locations of historical small-scale roasting sites in the Idrija surroundings were discovered. Ongoing geochemical study aims to determine the extreme pollution and significance of these sites for wider contamination of soils and aquatic systems. Presented studies have shown that Hg mining in Idrija caused intense pollution of local and regional environment including the aquatic systems in the Gulf of Trieste, which is seen as the final sink of a major part of the Hg stored in soils and rivers in the Idrija area.
COBISS.SI-ID: 1937493
Metal loads and heavy metal bearing phases were investigated in sediments draining Meža Vally. Sediments in the upper Meža Valley showed significant heavy metal pollution with lead, zinc as a consequence of mining and ore processing. Contents of Cr, Ni, Cu and Co are increased in the lower Meža River Valley, as a result of iron and steel industry. Heavy metal bearing phases identified in stream sediments were assigned to three influential areas, according to their source and genesis.
COBISS.SI-ID: 1931349