Abstract
Pšenk is one out of 21 localities of ancient roasting sites in the woods surrounding Idrija and one of the largest localities of roasting vessels fragments. The most abundant pottery remains are found in the central western part of the area, which is about 60 m long and up to 50 m wide and is supposed to be the location of the roasting process itself. Detailed soil sampling was performed on 210 x 180 m big area. 156 soil (0-15 cm and 15-30 cm) and humus samples were collected from 73 sampling points. 3 soil profiles were sampled to determine vertical distribution of Hg in soil. The prevailing soil types are Cambisols with the typical A-B-C layers sequence. In general soils are rich in organic matter to the depth of 30-40 cm; deeper the clayey loam prevails. The determined Hg contents in soil and humus samples of the investigated area are in the range 1.6-8,600 mg/kg with the median of 62.5 mg/kg. At the area of supposed roasting site the Hg contents range between 20 and 8,600 mg/kg with the median of 580 mg/kg. Spatial distribution of mercury in humus and soils of the investigated area show the highest Hg concentrations at the supposed roasting site area where the largest quantity of pottery fragments were found and to the east of this area, at the narrow tract between the footpath on the north and the bed of Lačna voda brook on the south. Extremely high Hg contents were found in profile P4 where it riches 37,020 mg/kg at the depth of 20-30 cm; in general Hg concentrations in all three studied profiles show a gradual decrease with depth. The soils of the investigated area are enriched with mercury to a high degree. Further investigations on Hg speciation are needed to determine the mobility and bioavailability of Hg in soil.
Highlights
Up to now 21 localities of ancient roasting sites were established on the neighbouring hills and in more distant localities; taking into account their extent and numerousness they represent a constant source of mercury emissions (^AR & TERPIN, 2005; GOSAR & ^AR, 2006)
In certain studies several anomalies were discovered in soils (HESS, 1993; GOSAR & ŠAJN, 2001) and sediments (GOSAR, 2008) where increased mercury contents cannot be the consequence of main Hg sources such as atmospheric emissions, mineralized rock dumps and smelting residues or their use in construction
The Hg contents in soil and humus samples of the investigated area are in the range 1.6– 8,600 mg/kg (N=156) with the median of 62.5 mg/ /kg
Summary
Numerous extensive and detailed investigations on mercury pollution were performed in Idrija region in the last decades (GNAMU{, 1992, 2002; HESS, 1993; PALINKA{ et al, 1995; GOSAR, 1997, 2008; GOSAR et al, 1997, 2006; BIESTER et al, 1999, 2000; HORVAT et al, 2003; GNAMU{ et al, 2000; GOSAR & ŠAJN, 2001, 2003; KOCMAN et al, 2004; GOSAR & ^AR, 2006; HINES et al, 2006; ŽIBRET & GOSAR, 2006). In certain studies several anomalies were discovered in soils (HESS, 1993; GOSAR & ŠAJN, 2001) and sediments (GOSAR, 2008) where increased mercury contents cannot be the consequence of main Hg sources such as atmospheric emissions, mineralized rock dumps and smelting residues or their use in construction.
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