engleski

Sedimentary records of Zrmanja River Estuary, eastern Adriatic coast – natural vs. anthropogenic impacts

Investigation of geochemical and sedimentological characteristics of sediments of Zrmanja River estuary was conducted in order to determine the deposition conditions as well as natural and anthropogenic factors of influences on sedimentation in this area. Zrmanja River eastuary is located in the central part of the eastern Adriatic coast, about 20 km from Zadar. It can be divided into three parts: the upper part (downstream part from Jankovic buk to Novigrad Sea), the middle part (Novigrad and Karin Sea) and the lower part (strait that connects the Novigrad Sea and the Velebit Channel) (Viličić et al., 2008). On the right bank of the river canyon, about 8 km upstream from the mouth of Zrmanja River into Novigrad Sea, the ex-alumina factory Jadral is situated. Although the factory had stopped working more than three decades ago, impact of plant activity on the surrounding environment can be seen a few hundred meters from the location of the factory, where the wind and the rain bearable aerosols and particles created infested landscape without vegetation. For purposes of this study, sediment cores were taken at several locations in Zrmanja River, Novigrad Sea, Karin Sea and Velebit Channel. Collected samples were subjected to geochemical and sedimentological analysis and the course of their treatment depended on their final use. The results of the analysis showed that the composition of sediments of Zrmanja River estuary is primarily determined by natural factors: the composition of bedrock, existing hydrodynamic conditions and isolation of studied basin. Nevertheless, antropogenic influence is observed as well. Composition of the Zrmanja River sediments indicates impact of the ex-alumina factory Jadral and transfer by wind of the material from its immediate proximity to the water system of the Zrmanja River. In addition, sedimentation in Zrmanja River was found influenced by the construction of reservoirs and power plant Velebit. The construction of power plant caused the change in the downstream water regime of the river, changing the energy of the water and deposition of finer fraction of sediment more downstream compared to the previous period, which is reflected in the grain size and geochemical characteristics of the sediments. It can be concluded that the composition of sediments of Zrmanja River estuary is still primarily determined by natural factors, although sporadically we find the impact of anthropogenic activities.

sediments; Zrmanja River estuary; Adriatic coast; trace elements

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