Heavy metals as environmental pollutants can have natural or anthropogenic origin. To determine the river sediment pollution status, it is crucial to have appropriate reference samples, free of anthropogenic impact, and natural reference samples should be used wherever and whenever possible. The collection of reference samples should be performed in the vicinity of the research area in a place that belongs to the same geological environment and is undisturbed by human activity. The main purpose of this study was to compare concentrations of heavy metals from different rivers with background values to show that the usage of natural background values is the best option when assessing pollution status, but also to underline that the natural background values have to correspond to the analyzed sediments. In this study, 5 river sediments from Sava, 17 from Great War Island (GWI), 11 from Danube, 24 from Tisa, 47 from Tamiš, and 11 from Timok were evaluated relative to reference samples from the Sava and Tisa Rivers. The results indicate that geological origin has a strong influence on the content of heavy metals in river sediments, primarily regarding concentrations of Ni and Co. Furthermore, Tamiš, Tisa, Sava, and Danube sediments are under strong anthropogenic influence.

Conventionally used spectrometric techniques of inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma optical emission spectrometry (ICP-MS) usually involve time-consuming sample preparation procedure of a sample dissolution which requires the usage of aggressive and toxic chemicals. The need for suitable and sustainable analytical methods for direct multi-elemental analysis of plant samples has been increased in recent years. Spectrometric techniques for direct sample analysis, instrumental neutron activation analysis (INAA) and X-ray fluorescence (XRF) have been applied in environmental studies and various fields of screening tests. Nevertheless, these techniques are not commonly used for plant sample analysis and their performances need to be evaluated. This research aimed to assess how reliable non-destructive techniques are in the determination of elements in plants compared to conventionally used spectrometric techniques. A total of 49 plant samples of four conifer species (Pinus nigra, Abies alba, Taxus baccata and Larix decidua) were measured using two conventionally applied (ICP-MS, ICP-OES) and two non-destructive techniques (wavelength dispersive XRF (WD-XRF), INAA). The comparison was performed by investigation of relative ratios of concentrations and by correlation analysis. Moreover, precision of the techniques was examined and compared. The quality control included analysis of NIST pine needles certified reference material (1575a) using all examined techniques. Our results suggest that additional analytical and quality control steps are necessary for reaching the highest accuracy of multi-elemental analysis.