Transport of hydrophobic pollutants in rivers such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and heavy metals is often facilitated by suspended sediment particles, which are typically mobilized during high discharge events. Suspended sediments thus represent a means of transport for particle related pollutants within river reaches and may represent a suitable proxy for average pollutant concentrations estimation in a river reach or catchment. In this study, multiple high discharge/turbidity events were sampled at high temporal resolution in the Globaqua River Basins Sava (Slovenia, Serbia), Adige (Italy), and Evrotas (Greece) and analysed for persistent organic pollutants such as PAHs (polycyclic aromatic hydrocarbons) or PCBs (polychlorinated biphenyls) and heavy metals. For comparison, river bed sediment samples were analysed as well. Further, results are compared to previous studies in contrasting catchments in Germany, Iran, Spain, and beyond. Overall results show that loadings of suspended sediments with pollutants are catchment-specific and relatively stable over time at a given location. For PAHs, loadings on suspended particles mainly correlate to urban pressures (potentially diluted by sediment mass fluxes) in the rivers, whereas metal concentrations mainly display a geogenic origin. By cross-comparison with known urban pressure/sediment yield relationships (e.g. for PAHs) or soil background values (for metals) anthropogenic impact - e.g. caused by industrial activities - may be identified. Sampling of suspended sediments gives much more reliable results compared to sediment grab samples which typically show a more heterogeneous contaminant distribution. Based on mean annual suspended sediment concentrations and distribution coefficients of pollutants the fraction of particle facilitated transport versus dissolved fluxes can be calculated.

The majority of the clinically approved iron oxide nanoparticles (IO NPs) used as contrast agents for magnetic resonance imaging (MRI) have been withdrawn from the market either due to safety concerns or lack of profits. To address this challenge, liposomes have been used to prepare IO-based T₂ contrast agents. We studied the influence of different phospholipids on the relaxivity (r₂) values of magneto-liposomes (MLs) containing magnetic NPs in the bilayer, where a strong correlation between the bilayer fluidity and r₂ is clearly shown. Embedding 5-nm IO NPs in the lipid bilayer leads to a significant improvement in their relaxivity, where r₂ values range from 153 ± 5 s⁻¹ mM⁻¹ for DPPC/cholesterol/DSPE-PEG (96/50/4) up to 673 ± 12 s⁻¹ mM⁻¹ for DOPC/DSPE-PEG (96/4), compared to “free” IO NPs with an r₂ value of 16 s⁻¹ mM⁻¹, measured at 9.4 T MRI scanner. In vitro MRI measurements, together with the ICP-MS analysis, revealed MLs as highly selective contrast agents that were preferentially taken up by cancerous T24 cells, which led to an improvement in the contrast and an easier distinction between the healthy and the cancerous cells. A careful selection of the lipid bilayer to prepare MLs could offer efficient MRI contrast agents, even at very low IO NP concentrations.

With the extensive use of silver nanoparticles (AgNPs) in various consumer products their potential toxicity is of great concern especially for highly sensitive population groups such as pregnant women and even the developing fetus. To understand if AgNPs are taken up and cross the human placenta, we studied their translocation and accumulation in the human ex vivo placenta perfusion model by single particle ICP-MS (spICP-MS). The impact of different surface modifications on placental transfer was assessed by AgNPs with two different modifications: polyethylene glycol (AgPEG NPs) and sodium carboxylate (AgCOONa NPs). AgNPs and ionic Ag were detected in the fetal circulation in low but not negligible amounts. Slightly higher Ag translocation across the placental barrier for perfusion with AgPEG NPs and higher AgNP accumulation in placental tissue for perfusion with AgCOONa NPs were observed. Since these AgNPs are soluble in water, we tried to distinguish between the translocation of dissolved and particulate Ag. Perfusion with AgNO₃ revealed the formation of Ag containing NPs in both circulations over time, of which the amount and their size in the fetal circulation were comparable to those from perfusion experiments with both AgNP types. Although we were not able to clarify whether intact AgNPs and/or Ag precipitates from dissolved Ag cross the placental barrier, our study highlights that uptake of Ag ions and/or dissolution of AgNPs in the tissue followed by re-precipitation in the fetal circulation needs to be considered as an important pathway in studies of AgNP translocation across biological barriers.

River ecosystems are exposed to various stressors. Among them, elements may contribute to overall pollution of riverine environments, in particular during the extreme flow events. To evaluate the influence of variable river flow conditions on the mobilization of potentially toxic elements (PTE) (Cr, Ni, Cd, Zn, Pb, As and Cu) from sediments into the overlaying waters of the Sava River, samples were collected in September 2014, during extremely high water discharges and in September 2015, under low water discharge conditions. In water samples the total element concentrations and the dissolved element contents (<0.45μm) were determined. Sediment pollution was estimated by determination of the total element concentrations and mobile element fraction (0.11molL^-1 acetic acid). Anthropogenic inputs of elements to sediments were evaluated by normalizing elemental against Al concentration. The results showed that concentrations of PTE in water were in general higher during high water discharges, while the soluble concentrations were higher during low water level conditions. Concentrations of PTE in the Sava sediments collected in 2015 were lower than those collected in 2014, mainly because during the extreme floods a mixture of bank sediment material and contaminated soil was sampled. Partitioning coefficients between suspended particulate matter (SPM) and soluble content of elements in the water under high and low flow conditions, indicated on different affinity of elements to SPM in relation to different flow regimes. The potential ecological risk posed by the simultaneous presence of PET in sediments was evaluated by Probable Effect Concentration Coefficient (PEC-Q) approach. Under high water level conditions, PEC-Qs were all above critical value 0.34 and derived mostly from anthropogenic inputs of Cr and Ni. Overall sediment toxicity was much lower under low water discharges. The data from this study importantly contribute to the knowledge regarding the behaviour of PTE under extreme flow events.