Milena Horvat

Elements and Persistent Organic Pollutants in the Sediments of the Sava River

Among various stressors, aquatic ecosystems are exposed also to different inorganic and organic pollutants. The pollution of the Sava River is related mainly to the release of industrial wastes, untreated effluents from municipalities, and contaminants arising from agricultural activities. To assess the geographical distribution of sediment pollution, sediments were analysed at selected sites along the Sava River. Total element concentrations were determined and mobile element fractions and anthropogenic inputs of elements assessed. Selected persistent organic pollutants: polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCB), and chlorinated pesticides were also determined. In industrially exposed sites, Hg, Cr, and Ni were found in moderate concentrations (up to 0.6, 380 and 210 mg kg−1, respectively). Since Cr and Ni exist in sparingly soluble forms, they do not represent an environmental burden. Elevated P concentrations up to 1,000 mg kg−1 were found at agricultural areas and big cities. Regarding elements, the environmental status of sediments of the Sava River is comparable to other moderately polluted rivers in Europe, if rivers impacted by mining are not considered. Among the organic pollutants PAH were present in moderate concentrations (sum of 16 PAH up to 2,000 ng g−1 with two exceptions with elevated PAH concentrations up to 4,000 ng g−1 located downstream the oil fields) and their concentrations increased downstream the river. Concentrations of PCB were low (the sum of 7 indicator PCB was below 4 ng g−1). Among selected pesticides, p,p′-DDT were found in moderate concentrations in sediments at two sampling sites in Croatia (up to 3 ng g−1) and HCB in high concentration in the city of Belgrade (91 ng g−1), although the use of these persistent pesticides has been banned for many years. Considering the organic pollutants, Sava is a moderately polluted river. The results of this study contribute to knowledge on the extent of pollution of sediments of European rivers and are important for water management institutes and local authorities, which may use these data for sustainable use, management, and protection of the Sava River water resources.

Chapter 3H:Mercury: Biomarkers of Exposure and Human Biomonitoring

Mercury is one of the most toxic metals and occurs throughout the environment as a consequence of natural sources and human activity. Mercury species are broadly classified into three categories (the metallic form, also called the elemental form, the divalent inorganic forms, and organic mercury compounds), which have different toxicokinetic properties.The selection of biological media to assess human exposure depends on the mercury compounds, exposure pattern (e.g. chronic, acute) and time of sampling after the exposure. Exposure to elemental mercury is well represented by the presence of mercury in urine. Scalp hair has widely been used as a good indicator of methyl mercury exposure through the diet. As a biomarker of prenatal exposure, mercury in umbilical cord blood and not maternal blood is measured preferentially. In the blood, methyl mercury accumulates mainly in the red blood cells, while an exposure to elemental mercury leads to increased concentration of mercury in the plasma. Therefore, through the analysis of total mercury in these blood samples it is possible to differentiate between exposure to elemental and methyl mercury.Although the poisoning nature of mercury is well acknowledged, less known are the effects of mercury on humans as a consequence of long term exposure to low concentrations. In many cases the use of biomarkers, such as mercury concentrations in blood and urine, is not sufficient to assess the internal doses and potential effects on the central nervous system, kidney, the immune system, and other possible effects. Therefore, better scientific understanding of risks to human health, especially to those citizens living close to potentially contaminated sites and those exposed to low levels over a long period of time, is needed.