###### Abstract
This study acknowledges that there are no universally true background values [29; 30; 31; 32; 33; 34]. In the authors' opinion, assessing the geochemical influences on a regional level is more valuable and accurate, considering the sediment transport in each major river catchment area. This approach would yield geochemical background values contingent on the superimposition of geochemical characteristics across countries and regions. In exceptional instances, the sediment transported from a geologically significant region to another via major rivers and tributaries may exert an influence on the background values that have to be established for the specific watercourse. A study conducted between 1994 and 2006 by the Geological Institute of Romania (IGR) in collaboration with the Federal Institute for Geosciences and Natural Resources of Hannover, Germany (Bundesanstalt fur Geowissenschaften und Rohstoffe--BGR), had the objective of determining the geochemical background values for chemical elements in Romanian stream water and sediment. The sampling was conducted in areas unaffected by industrial activity or other anthropogenic effects. The specific locations were selected to represent the dominant geological unit in the respective sampling zone. The aforementioned study culminated in creating a geochemical atlas at a scale of 1:3,000,000 [60]. The present study established the geochemical background relevant in Romania for the trace elements As, Cd, Cr, Cu, Ni, Pb, and Zn using data from the 2006 Geochemical Atlas of Romania. The data set comprises analysis results generated by sediment samples from 167 locations distributed relatively uniformly throughout the country and distant from known local contamination sources. Box-plots were constructed and employed from the data set for each selected trace element to facilitate the removal of outliers. Subsequently, the median and its corresponding median absolute deviation (MAD) were extracted from the filtered data sets. The geochemical background for Romania was established as the median \(\pm\) 2 MAD extracted from the data sets after removing outliers for each of the selected trace elements from the Geochemical Atlas of Romania. As mercury was not included in the Geochemical Atlas of Romania, the value measured in 2020 in an excavation located in the Danube River floodplain sampled at 3.3 m below ground surface was considered the geochemical threshold of this element for the present work, in lieu of more relevant data. Except for Cr and Ni, the geochemical threshold obtained was below the quality standard stipulated in Romanian legislation for sediments [42]. This quality standard was based on the Dutch standard, with only two minor modifications. As previously stated, the thresholds used in this study are deemed more suitable for Romania, as they reflect the country's distinctive geology. The pollution indices were calculated for samples collected from the same locations as those used in previous studies [61, 62], although the comparison was made with different reference values, and the analyses were conducted in a different laboratory. The elevated threshold levels of Cr and Ni in Romania, which are higher than the Dutch standard and the country's legislative requirements, have been subjected to detailed scrutiny. This investigation has sought to corroborate information derived from various geochemical prospecting studies. The findings indicate that these elevated threshold levels are consistent with the geology of the Carpathian-Balkan region. Considering these observations, a proposal for updating the reference values in the specific legislation should be submitted to the Romanian Ministry of Environment, which issued Order 161/2006 [42]. The novelty of this study consists of establishing the level of anthropogenic pollution of sediments (evaluated through different indices) by starting from the regional geochemical background and not from a set of normal reference values (sometimes, these are established only considering the toxicological potential of substances).