Calculation of mercury accumulation in the Idrijca River overbank sediments

摘要

From the historic literature on the Idrija mercury mine it is evident, that part of the smelting and mining waste was dumped into the Idrijca River. This waste was transported downstream during floods. The amount of mercury, which is accumulated in the overbank sediments of the Idrijca River today, was studied. For estimating the volume of overbank sediment we performed the mapping of Holocene river terraces of the Idrijca River. For assessment of mercury concentration we sampled the overbank sediments on the different levels to perform the analysis of variability. The greatest variability is between the different terases inside the same floodplain, regardless with the distance from the source of pollution, with the position inside one terrace or with the depth of a taken sample. Considering this fact, which determined the methodology for calculation, we estimated that about 1500 tons of mercury is stored in the Idrijca River overbank sediments.