Page 17 - Osor v fokusu znanosti

Five Millennia of Human Influence Recorded
in the Geochemical Composition of Marine
2025
Sediments from Osor Bay

Slobodan Miko, Dea Brunović, Ozren Hasan, Nives Doneus,
Nikolina Ilijanić, Petra Hus, Filip Šegović, Ivan Razum, Michael Doneus,
and Martina Šparica Miko November
Invited Lecture

4–5

Abstract Holocene sediments from Osor Bay were analyzed to distinguish
between natural and human imprints in sedimentary records. Two dated Koper,
cores from Osor’s northern side were geochemically analysed to obtained
proxies for anthropogenic impact and sediment source identification. The •
distal core (OSOR-1M) spans the entire Holocene, while core OSOR-2M, lo-
cated closer to Osor, spans the last 8000 years. Anthropogenic environmen- Spotlight
tal changes were assessed using calculated enrichment factors (EF) for Cu/Zr,
Pb/Zr, Mo/Zr, and Zn/Zr ratios, along with organic carbon content as an indi-
catorofcharcoalcontent,andtotalPcontent.TheCr/Zr,Rb/Zr,andV/Zrratios
were employed to detect changes in geogenic sources within the sediment Scientific
geochemistry. In the OSOR-2M core, organic carbon content (charcoal), Cu
and Mo concentrations, and total P increased from 3672-3364 cal BCE, peak-
ing between 270–584 cal AD. The Cr/Zr, Rb/Zr, and V/Cr ratios, serving as ge- the
ogenic source proxies, suggest sediment influx from the Lošinj Channel and in
thus the establishment of a marine connection with the Lošinj Channel. This
connection likely occurred between 1500 and 1000 BCE, probably due to sea Osor
level rise and the flooding of a natural morphological low. The increased EF
for Pb is associated with the Roman period and was absent in earlier times.
During the industrial era, Pb and P concentrations rose, while organic carbon,
Cu, and Mo concentrations declined. Although the Osor area was inhabited
during the Neolithic period, no discernible environmental impact is evident
in the sediment geochemistry.

Keywords Osor, Late Holocene, marine sediments, enrichment factors, en-
vironmental change

© 2025 Author(s) 17