Naslov
Holocene environmental record from lake sediments in Bokanjačko blato (Dalmatia, Croatia)

Autori
Ilijanić, Nikolina ; Miko, Slobodan ; Hasan, Ozren ; Bakrač, Koraljka

Izvornik
Quaternary international (1040-6182) 494 (2018); 66-79

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
karst polje, Bokanjačko blato, lake sediments, carbonates, Holocene, environmental changes.

Sažetak
Karst polje Bokanjačko blato is typical karst depression along the Eastern Adriatic coast, filled with lake sediments. It is an important hydrological area since the wells in a southern part of the polje are used for water supply of surrounding towns and villages. However, the evolution of the polje is poorly understood. A 7.8 m long sediment core from the south-eastern part of the polje provides a reconstruction of the depositional processes in the polje over the last 10.3 ka cal BP, using multiproxy approach. Sedimentological, mineralogical and geochemical characteristics indicate that the whole sediment sequence is lake sediment, with a variable amount of carbonates and silicates, thus the lake existed for approximately 10 300 years before it was drained by human intervention in the 1960s, for agricultural purposes. Depositional changes are evident throughout the core. From 10.3 to 7 ka cal BP, higher magnetic susceptibility and concentrations of lithogenic elements indicate increased erosion and input of the material from the catchment and thus wetter climatic condition, but the lake level was lower due to lower sea level. The deposition of the siliciclastic detrital material gradually decreases and after 6 ka cal BP, dominant carbonate sedimentation occurs, with a minimum detrital siliciclastic material. Such conditions in carbonate sandy silt sedimentation remain until present. Lake level gradually increases from 6 to 5.2 ka cal BP, evident by higher carbonate content and lower detrital material, and reaches its maximum between 5.2 and 4.4 ka cal BP. From 4.4 ka cal BP there is possible lowering of the lake level due to higher nutrients and organic compounds (S and P), prior to human intervention and hydro melioration for agriculture. High concentrations of the nutrient element (P) and Pb, Cu and Zn in the upper 40 cm of the sequence, indicate the influence of agricultural activities in the polje and anthropogenic atmospheric pollution. Geochemical and sedimentological proxies illustrate a centennial scale variability in carbonate deposition and erosional run-off processes that could be compared with the role of natural climate and anthropogenic factors in the history of polje during the Holocene in central Mediterranean.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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