Naslov
Rječina River sediments (Croatia): from captured spring to polluted prodelta

Autori
Frančišković-Bilinski, Stanislav ; Juračić, Mladen ; Tibljaš, Darko

Izvornik
Environmental Earth Sciences (1866-6280) 64 (2011), 7; 1755-1761

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

Ključne riječi
Rječina River; prodelta; sediments; mineral composition; chemical composition; pollution

Sažetak
Surface sediments (fraction <63 μm) from source to the mouth of the Rječina, short (18.3 km) karst alogene river in Croatia, which is an important source of drinking water, were studied to investigate their mineral (by XRD) and chemical (by ICP-MS) composition in order to check possible anthropogenic influence at the lower course due to paper industry and mills, and in the prodelta area from untreated municipal sewage and large harbor of Rijeka town. In all analysed sediment samples and in the sandstone source rock quartz is a major mineral, while feldspar and mica group minerals are less abundant. Chlorite is a minor or trace mineral in all samples. Calcite and dolomite are abundant in the river prodelta, reflecting changes in bedrock lithology from flysch to carbonates. In river sediments Fe is the most abundant analyzed element, while Ca is the most abundant in prodelta sediments. Concentrations of Al, Mn, Ni, Cr, Co, La and Nd decrease downstream, while Mg, S, Na, B, Pb, Zn, As, Sn, U, Mo, Hg and Ag have relatively higher concentration in prodelta sediments. The results are compared with sediments of other rivers in the area: the Raša, the Rižana and the Dragonja, as well as with those of the Rosandra Creek (Italy). Sediments in the Raša River showed similar behavior like those in the Rječina, as the highest concentration of metals was found in the restricted upper part of the estuary, characterized by rapid deposition of clay particles and terrestrial sedimentary organic matter. The comparison also showed that the most contaminated were the sediments from the Rižana, followed by those from the Rječina and Rosandra Creek, whose results are similar. Among the studied elements, As is present in all sediment samples at concentrations >6 ppm, that might cause lowest toxic effects. At the lower Rječina and in prodelta sediments Pb is also present at slightly elevated concentrations (>31 ppm) that could cause such effects. Concentrations of Zn in prodelta, corresponds to those occurring in moderately polluted sediments (90-200 ppm). In the prodelta sediments Hg is slightly below toxicity threshold (1 ppm), while Ag is present at toxicity threshold (0.5 ppm) or close to it. Rječina River could act as a good illustrative example for behavior of toxic metals in alogene karstic rivers, in which accumulation of anthropogenically introduced pollutants usually occurs in their estuaries, as result of fine particles transport and deposition.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA