Naslov
Distribution and behavior of selected elements in soil over a historical Pb-Ag mining site at Sv. Jakob, Croatia

Autori
Durn, Goran ; Čović, Marta ; Barudžija, Uroš ; Namjesnik-Dejanović, Ksenija ; Miko, Slobodan ; Palinkaš, Ladislav

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Geochemical Exploration - Abstracts-book / Fletcher, W.K; Elliot, I.L ; - Vancouver : Venue West Conference Services LTD, 1999, 69-70

Skup
19th International Geochemical Exploration Symposium

Mjesto i datum
Vancouver, Kanada, 10.04.1999. - 16.04.1999

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Pb-Ag historical mining site; soil pollution; sequential extraction; Mt. Medvednica protected park of nature

Sažetak
The purpose of this study was geochemical assessment of soils developed on a historical Pb-Ag mining site (galena with approx. 500 mg/kg of Ag) situated near the chapel of St. Jacob on the crest of Mt. Medvednica near Zagreb. A total of 100 brown forest topsoil (0-25 cm) soil samples was collected on dense regular grid covering an area of approximately 1.5 km2. Ten samples were selected for detailed chemical and mineralogical analyses.Trace metal values were obtained from aqua regia extracts, while their residence sites in soils were identified by sequential extraction. Shallow soils developed above the historic mining site “Sv. Jakob” contain very high concentrations of Pb, Zn and Cd due to oxidation of primary sulphides in near-surface weathering environment. The aqua regia extractable Pb values varied from 9 to 18000 mgg-1, Zn 12-9000 mgg-1, Cd from <0.1 to 180 mgg-1, and total Hg from 10 ngg-1 1800 ngg-1. Distribution patterns of Pb, Zn, Cd and Hg outline both the surface extent of mineralization and the area effected by historical mining activities (tailings, exploration pits and trenches) which are today almost indistinguishable from the natural landscape. Pb and Cd are dominantly enriched in carbonate and Fe-Mn oxide fractions while Zn exhibits enrichment in organic-sulphide and Fe-Mn fractions. This is probably the result of solubility controls for Cd and Pb in carbonates, affinity of Zn for organic material and coprecipitation of these elements with iron oxides. Fe, Cu and Ni are enriched in organic-sulphide fraction, indicating that a part of pyrite has probably not been altered completely (or is recently incorporated in soil as a result of downslope movement and coluviation), and in the residual fraction. For the sequential extraction procedure used in this study, mobility and biological availability are assumed to decrease in the order of the metal extraction sequence. On this basis, the apparent mobility and potential bioavailability of the metals for contaminated soils are: Cd > Pb > Zn > Cu > Ni. Spatial distributions and high contents of Pb, Hg, and Zn in topsoils of the northern lowland residential parts of Zagreb were attributed only to fossil fuel consumption and the flooding of the river Sava. The high contents of these elements in topsoils covering areas of historical mining sites situated within the Mt. Medvednica Protected Park of Nature probably are also sources of observed pollution. Namely the streams that drain these areas are characterised by violent mudflows that flood northwestern parts of the city at least once every three years and deposit high quantities of mud. Studies that aim to determine this link are currently in their initial phases but evidently materials with high bioavailable contents of potentially toxic elements are been regularly supplied to the gardens and orchards of northwestern parts of Zagreb.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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