Preliminary results of detailed geochemical study of mercury at the ancient ore roasting site P{enk (Idrija area, Slovenia)
Tamara Teršič, Mateja Gosar
2009
Geologija
P{enk 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
more »
... ints. 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 La~na 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. Izvle~ek P{enk je ena izmed 21 lokacij nekdanjih žgalni{kih mest v gozdovih okrog Idrije in eno ve~jih nahajali{~ drobirja žgalni{kih posod. Najve~je koli~ine lon~enine najdemo na približno 60 m dolgem in do 50 m {irokem predelu v centralnem zahodnem delu obravnavanega obmo~ja, ki domnevno predstavlja ožje obmo~je žgalnice. Na raziskovanem ozemlju v velikosti 210 x 180 m je bilo na 73 vzor~nih lokacijah odvzetih 156 vzorcev tal (0-15 cm and 15-30 cm) in humusa. Za dolo~itev vertikalne razporeditve Hg v tleh so bili vzor~eni 3 talni profili. Prevladujo~i talni tip so kambi~na tla s tipi~nim profilom A-B-C. Tla so v splo{nem bogata z organsko snovjo do globine 30-40 cm, globlje pa prevladuje glinasta ilovica. Vsebnost živega srebra v obravnavanih vzor~nih medijih zna{a v povpre~ju 62,5 mg/kg in niha v razponu od 1,6 do 8.600 mg/kg. Na ožjem obmo~ju žgalnice se vrednosti gibljejo med 20 in 8.600 mg/kg, mediana zna{a 580 mg/kg. Prostorska razporeditev živega srebra v humusu in tleh kaže najvi{je vrednosti na domnevnem ožjem obmo~ju žgalnice in vzhodno od tega obmo~ja, na predelu med gozdno potjo na severu in strugo potoka La~na voda na vzhodu. Ekstremno visoke vsebnosti Hg so bile dolo~ene v profilu P4, kjer dosežejo na globini 20-30 cm vrednost 37.020 mg/kg; v splo{nem vsebnosti Hg v vseh treh obravnavanih profilih postopoma upadajo z globino. Tla na obravnavanem obmo~ju so mo~no obogatena z živim srebrom, zato so potrebne nadaljnje raziskave zvrsti živega srebra, ki bodo omogo~ile dolo~itev mobilnosti in bio-dostopnosti živega srebra v tleh.
doi:10.5474/geologija.2009.009
fatcat:2nccahh46ff2pc7rbcwyob4kcy