The Mississippi Valley-type (MVT) Pb–Zn ore district at Mežica is hosted by Middle to Upper Triassic platform carbonate rocks in the Northern Karavanke/Drau Range geotectonic units of the Eastern ...Alps, northeastern Slovenia. The mineralization at Mežica covers an area of 64 km
2
with more than 350 orebodies and numerous galena and sphalerite occurrences, which formed epigenetically, both conformable and discordant to bedding. While knowledge on the style of mineralization has grown considerably, the origin of discordant mineralization is still debated. Sulfur stable isotope analyses of 149 sulfide samples from the different types of orebodies provide new insights on the genesis of these mineralizations and their relationship. Over the whole mining district, sphalerite and galena have
δ
34
S
values in the range of –24.7 to –1.5‰ VCDT (–13.5 ± 5.0‰) and –24.7 to –1.4‰ (–10.7 ± 5.9‰), respectively. These values are in the range of the main MVT deposits of the Drau Range. All sulfide
δ
34
S
values are negative within a broad range, with
δ
34
S
pyrite
<
δ
34
S
sphalerite
<
δ
34
S
galena
for both conformable and discordant orebodies, indicating isotopically heterogeneous H
2
S in the ore-forming fluids and precipitation of the sulfides at thermodynamic disequilibrium. This clearly supports that the main sulfide sulfur originates from bacterially mediated reduction (BSR) of Middle to Upper Triassic seawater sulfate or evaporite sulfate. Thermochemical sulfate reduction (TSR) by organic compounds contributed a minor amount of
34
S-enriched H
2
S to the ore fluid. The variations of
δ
34
S
values of galena and coarse-grained sphalerite at orefield scale are generally larger than the differences observed in single hand specimens. The progressively more negative
δ
34
S
values with time along the different sphalerite generations are consistent with mixing of different H
2
S sources, with a decreasing contribution of H
2
S from regional TSR, and an increase from a local H
2
S reservoir produced by BSR (i.e., sedimentary biogenic pyrite, organo-sulfur compounds). Galena in discordant ore (–11.9 to –1.7‰; –7.0 ± 2.7‰,
n
= 12) tends to be depleted in
34
S
compared with conformable ore (–24.7 to –2.8‰, –11.7 ± 6.2‰,
n
= 39). A similar trend is observed from fine-crystalline sphalerite I to coarse open-space filling sphalerite II. Some variation of the sulfide
δ
34
S
values is attributed to the inherent variability of bacterial sulfate reduction, including metabolic recycling in a locally partially closed system and contribution of H
2
S from hydrolysis of biogenic pyrite and thermal cracking of organo-sulfur compounds. The results suggest that the conformable orebodies originated by mixing of hydrothermal saline metal-rich fluid with H
2
S-rich pore waters during late burial diagenesis, while the discordant orebodies formed by mobilization of the earlier conformable mineralization.
Two approaches, factor analysis (FA) and self-organising maps (SOM), have been used for the determination of geochemical associations in the two case studies evaluated here. In both case studies, ...different associations of elements, derived from different anthropogenic sources (smelters, ironworks, and chemical industry), are presented, together with natural associations of elements, all representing different geological environments. FA and SOM give similar results, despite some differences. Most similarities were achieved with the group of elements affected by strong pollution caused by smelting activities. The biggest difference between the two is that SOM can combine different groups into one, especially in the case of associations of elements connected with mild pollution (ironworking, chemical industry). The biggest advantage of SOM as opposed to FA is that SOM allow us to process variables, which are not normally distributed, or even of attributive nature. The use of such variables in SOM classification to prove the origins of associations of elements is also demonstrated here.
Extended description:
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V Mežici noč in nad njo teče svinec. Rudarji so nam povedali, da je bil napovedan mežiškemu rudniki in topilnici ...konec že leta 1949, vendar se je produkcija do danes stalno večala. Lani so odkrili nova rudišča pod Uršljo goro in to je kolektiv še bolj prepričalo, da so velika lastna sredstava, ki jih vlagajo v modernizacijo obratov dobro naložena. Velike bobnaste peči so v lanskem letu dale 16.325 ton svinca, kmalu pa bodo dajale letno še 5.000 ton več.
Iz topilnice v žerjavu potiskajo veliki ekshaustorji škodljive pline v bližno dolino, ki jo na pol za šalo domačini imenujejo tudi »Dolina smrti«. Škodljivi vpliv sega 5 km daleč in vso škodo v gozdartvu in poljedeljstvu so ocenili na več kot 10 milijonov dinarjev letno. Če bi jim uspela investicija ene milijarde dinarjev bi tu lahko zgradili donosen obrat za pridobivanje žveplene kisline in natrijevega sulfata.
Information:
The town of Mežica: environmental pollution with noxious gases from the mercury smelting plant; the Žerjav smelting plant, masked workers and destroyed forests in the Mežica Valley.
Original language summary:
Mežica: onesnaževanje okolja s strupenimi plini iz topilnice svinca; topilnica Žerjav, delavci z maskami, gore, uničeni gozdovi v Mežiški dolini.
Extended description:
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Prispevek ob ekološki katastrofi v Mežici, z izjavami Avgusta Osojnika, ribiškega čuvaja, Marte Šisemik, okoljevarstvene inšpektorice in Mateje Vidmar, TAB (Tovarna akumulacijskih baterij) Mežica.
The clip presents the background and some opinions regarding the ecological catastrophe in Mežica, with statements from Avgust Osojnik, head of a fishing watch, Marta Šisemik, the environmental inspector and Mateja Vidmar, representative for TAB Mežica.
Information:
Factory of batteries, Mežica caused an ecological disaster with omissions from production waste acid into the river Meža, causing a massive rate of fish mortality in the river.
Original language summary:
Tovarna akumulatorjev baterij Mežica je ob izpustu kisline v reko Mežo povzročila ekološko katastrofo in pogin rib.
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Večstoletno rudarjenje in predelava svinca je uničilo naravno okolje v Mežiški dolini. Uničeni gozdovi so alpsko dolino spremenili v dolino smrti. O problemih življenja v onesnaženi dolini govorijo prizadeti domačini in strokovnjaki, pevec Marjan Smode pa je o dolini napisal nekaj pesmi (med njimi je v Sloveniji najbolj znana Mrtva reka - Dead River); izjave Andrej Šertel, vodja za gojenje in varstvo gozdov Lesna Slovenj Gradec, Karl Markovič, predsednik lovske družine Bistra, Pavel Srebre, Martin Srebre, Marija Šepul, ing. Peter Sovan, vodja projektne skupine za okolje Rudnik Mežica, dr. Bojan Jezernik, zdravnik ZD Ravne na Koroškem, Filip Šepul, kmet.
The consequences of hundreds of years of lead mining in the valley of the river Meža; destroyed forests and have changed the valley into a valley of death. The affected citizens and experts talk about the issues arising from living in the polluted valley. The singer Marjan Smode wrote several songs about the polluted valley (most recognizable of them entitled, Mrtva reka - Dead River). Statements by Andrej Šertel, head of the section for cultivation and protection of the forest Lesna Slovenj Gradec, continuing with Karl Markovič, head of the hunting family Bistra, and participants of the project group for the preservation of Mežiška dolina, Pavel Srebre, Martin Srebre and Marija Šepul as their project leader, the engineer Peter Sovan, a statement by the medical doctor Bojan Jezernik, ending the clip with a statement by a local farmer Filip Šepul.
Information:
Eliminating the consequences of centuries of mining, saving the natural forest and the heavily polluted environment of Mežiška dolina.
Original language summary:
Odpravljanje posledic večstoletnega rudarjenja, reševanje gozdov in naravnega okolja v močno onesnaženi Mežiški dolini.
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Izjava Božidarja Gomilška, vodje projekta za ekološko sanacijo Mežiške doline, čistilna naprava za SO2, izjava Mirko Kret, direktor MPI-ja (Metalurgija plastika inženiring) s panoramo Mežiške doline - gola pobočja v snegu, posledica 300 letnega rudarjenja v Mežiški dolini.
A statement by Božidar Gomilšek, project leader for the ecological rehabilitation of Mežiška dolina, footage of cleaning system for SO2 releases, a statement by Mirko Kret, Director of MPI (Metallurgy and plastics engineering) with panoramic views of the valley Meža - bare snow slopes, the result of 300 years of continuous mining in Mežiška dolina.
Information:
Ecological restoration of Mežiška dolina, its environmental protection and a prohibition regarding the release of toxic gases into the atmosphere.
Original language summary:
Ekološka sanacija Mežiške doline, zaščita okolja in prepoved izpusta strupenih plinov v ozračje.
Extended description:
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Več stoletij dolga izraba svinčene rude je v Zgornje Mežiški dolini pustila neizbrisen pečat. Rudniki svinca in cinka v Mežici so s pridobivanjem svinčene rude področje zgornje Mežiške doline spremenili v onesnaženo okolje z visoko vsebnostjo svinčenega prahu v zraku in tleh.
Svinec v Mežiški dolini; panorama Mežica - rudnik, voda, okolica, dimniki, proizvodnja, poroča Slavko Bobovnik med otroki v vrtcu, njive, vrtovi, delo v gredi, proizvodnja.
The several centuries practiced use of lead ore in the upper part of Mežiška dolina has left an indelible mark. Lead and zinc ore mining has changed the upper part of the valley and transformed it into a polluted area with high levels of leaden dust in the air and soil. Panoramic view of Mežica - mines, water, surroundings, manufacturing and the reporter Slavko Bobovnik amongst some children in the kindergarten, fields and gardens.
Information:
The impacts of centuries of lead mining on the environment and the adverse consequences for the inhabitants of the valley, including the impact on the health of the children.
Original language summary:
Vpliv večstoletnega izkoriščanja rudnika svinca na okolico in škodljive posledice za prebivalce doline, med njimi tudi vpliv na zdravje otrok v vrtcih.