Purpose: Riparian zone contamination is a growing problem for several European catchments due to high anthropogenic pressures. This study investigates As, Cd, Cr, Cu, Ni, Pb, and Zn concentrations in the Sava River riparian zone, characterized by wide agricultural areas, various geological substrates, and different types of industrial pollution. The accumulation and mobility of these elements were studied because they are listed as priority substances in the Water Framework Directive and environmental objectives for surface waters. Materials and methods: Sampling was performed during the sampling campaign of the EU 7th FW-funded GLOBAQUA project in September 2015 during a low-water event. Soil samples were collected along the Sava River at 12 selected sampling sites, from a depth of 0–30 cm, at a distance of 10–15 m from the river bank. The extent of pollution was estimated by determining total and readily soluble element concentrations in the soils. Potential ecological risk and the source of the selected elements in the soils was determined using the enrichment factor (EF), potential ecological risk index (RI), and statistical methods such as the principal component analysis (PCA) and multiple linear regression analysis (MLRA). Results and discussion: This study showed that concentrations of the selected elements increase along the Sava. In terms of origin, PCA and MLRA indicated that Cr and Ni in soils are predominantly lithogenic, while As, Cd, Pb, and Zn are both lithogenic and anthropogenic (ore deposits, industry, and agriculture). PCA singled out Cu since its origin in soil is most probably from specific point-source pollution. EF was generally minor to moderate for most of the examined elements, apart from Cu, for which the EF was significant at one sampling site. Overall ecological risk (RI) fell within the low-risk category for most sites, apart from Belgrade sampling site (BEO), where high total Cd content affected individual and overall ecological risk indicators, indicating Cd could represent a considerable ecological risk for the downstream riparian zone. Conclusions: At downstream sites, there was a noticeable increase in PTE content, with Cd, Cr, Ni, and Zn exceeding the proposed threshold values for European soils, indicating rising contamination in riparian soils. In terms of the ecological risk, only Cd could pose a potential ecological threat for the downstream riparian zone.

In this study, both seasonal and spatial variations in trace metal uptake, as well as concentration of photosynthetic pigments in Silver birch (Betula pendula Roth.) trees in five urban parks in Pancevo, Smederevo, Obrenovac and Belgrade (Serbia) affected by different anthropogenic activities were studied. The characteristics of soil were assessed in terms of texture, pH and trace element content. Concentrations of boron, strontium and zinc in both leaves and bark showed an increasing temporal trend, however, copper showed an opposite seasonal trend. A higher accumulation of trace elements was noticed in leaves compared to bark. The obtained results for photosynthetic pigments showed low sensitivity of birch to B, Cu, Sr and Zn contamination, indicating that birch tolerates pollution and climate stress by increasing the amount of pigments. Analysis of the effects on soil chemistry of trace element accumulation in plant tissues proved that soil chemistry poorly explains the variability of elements in bark (27.6 %) compared to leaves (82.99 %). Discriminant analysis showed that Belgrade and Smederevo are clearly separated from the other three sites.

This study evaluated the source apportionment and level of contamination with potential toxic elements (PTEs)—As, Cd, Cr, Cu, Ni, Pb and Zn—in a riparian zone of the Sava River by calculating the Enrichment Factor (EF) and the Geo-Accumulation Index (Igeo). The study analysed the non-carcinogenic and carcinogenic health risks to both adults and children in the local population. Soil and sediment samples collected during high and low water events from 12 sites along 945 km of the river were screened. Elevated soil contents of As, Cr, Cu, Ni, and Zn were observed along the middle and lower stretches from Županja (ZUP) to Belgrade (BEO), and an elevated Cu content was detected in the upper stretch Čatež (CAT), highlighting these elements as a potential risk for the human population. Elevated As, Cd Cr, Ni, and Zn levels in the sediment were also detected, with the Ni content three times higher than the Permissible Exposure Limit (PEL) values, indicating high contamination. The study established that As, Cr, and Ni primarily originate from geological sources; Cu, Pb, and Zn are predominantly from anthropogenic sources; and Cd originates from both geological and anthropogenic sources. Although the EF and Igeo varied along the entire river stretch, they were significantly higher for most elements in the lower stretch, indicating intensive anthropogenic contamination and potential health risks. The carcinogenic and non-carcinogenic risks associated with soils and sediments during high and low water events did not imply a potential risk for adults. However, As, Cd, Cr, and Pb potentially pose the greatest non-carcinogenic risk for children in both high and low water events, with ingestion as the main route of exposure. According to our findings, the elevated concentrations of As, Cd, Cr, and Pb in the Sava River basin (SRB) pose a significant potential health risk to the local population based on several factors: the high levels of these elements, their potential contamination risk as determined by the EF and Igeo, and their bioavailability and solubility. Although the cumulative Total Hazard Index (THI) and Total Carcinogenic Risk (TCR) values are low, particularly in the lower stretch of the Sava River, these elements still present a high potential health threat.