Organic and inorganic priority substances in sediments of Ludaš Lake, a cross-border natural resource on the Ramsar list.

For the first time, long-term monitoring (from 2002 to 2014) was carried out of surface sediments in Ludaš Lake, a Ramsar site in northern Serbia. Organic (16 EPA PAHs, mineral oils, selected pesticides and polychlorinated biphenyls (PCBs)) and inorganic substances (eight heavy metals: Ni, Zn, Cd, Cr, Cu, Pb, As and Hg) were continually investigated. Dibenzo[a,h]anthracene (DahA) and fluorene (Flo) were found at levels indicative of causing adverse effects to biota. Diagnostic ratios of specific PAHs were dominated by high molecular weight components, particularly DahA, which contributed 81.78 % of the total high carcinogens, benzo[b]fluoranthene (BbF) and Flo. Potential ecological risk factors (ERi) and the high relative standard deviations (RSD) obtained (up to 245 %) for the parameters monitored confirm the high periodical anthropogenic impact from industry, municipal wastewater and agriculture. The highest concentration of inorganic pollution found was for Cd (440-831 mg/kg) at all sites, Cu (439 mg/kg) in the eastern part of the lake and Cu (388 mg/kg) and Hg (771 mg/kg) in the northern part of the lake. Based on factor analysis of principal component analysis (PCA/FA), As and phenanthrene (Phe) had significant loadings (0.808 and 0.907, respectively). This association of As with organic anthropogenic sources was also confirmed with the sum of PAHs, pyrene (Pyr) and mineral oil by 3D factor plot, corroborating the theory of As mobilization from metal-reducing microbes as organic (methylated) forms, accelerated by phenanthrene. According to EU national and regional data results, this research suggests that Cu, As, dibenzo[a,h]anthracene and Flo should be added to the list of priority pollutants within the context of applying the European Water Framework Directive (WFD).