| Popis: |
Lake sediments are considered as a good sample for tracking environmental changes and anthropogenic influence on lake systems and its surroundings and they can serve as an important reservoir of all substances introduced into the environment. Vransko Lake is located in the geographical region of Ravni Kotari (North Dalmatia), Croatia. The objective of the study was to investigate the Vransko Lake sediments and soils from a nearby landfill. Heavy metals concentration can be used as an indicator of possible changes that occurred in the monitored environment. Speciation of selected elements from lake sediment and soil samples was done by applying modified BCR sequential extraction procedure. Inductively coupled plasma atomic emission spectrometry, ICP-AES, was used for determination of metal content in all fractions. Accuracy was determined by analysis of certified reference materials (BCR 701, GBW 07410 and SRM 1646). Recovery was within 100±10%, indicating good quality of the results. Precision of the measurements was 2-5% RSD. An increase of mobile fraction for elements Cr, Co, Mn and Fe obtained from data and distribution maps throughout the lake, for each step of BCR was established. Analysis and distribution maps pointed out zone in which a higher amount of Cd, Cu and Zn were determined. The ecological risk index was defined by the model proposed by Hakanson and it shows a significant difference between a central part of the lake and its shore. |
