## 4 Discussion
In this context, as shown in [34], when considering the whole European continent [117], using the threshold values for trace elements established in the legislation of one northern European country (Finland) suggested severe contamination with Cr and Ni in the Balkan peninsula, if the regional geological conditions were not considered in the interpretation. Figure 8: Geological map of SE Europe. Red lines delimit geological provinces: 1103—Dobrogea foreland; 4048—Pannonian Basin; 4051—Alps; 4057—Transylvania; 4061—Carpathian-Balkanian Basin; 4063—Dobrogea Orogen; 4064—West Black Sea Basin; 4071—Dinaric Alps; 4075—Aegegan. Used with permission [[PERSON], Wikimedia Commons user [PERSON], CC BY-SA 3.0, [[https://commons.wikimedia.org/w/index.php?curid=11171117](https://commons.wikimedia.org/w/index.php?curid=11171117)]([https://commons.wikimedia.org/w/index.php?curid=11171117](https://commons.wikimedia.org/w/index.php?curid=11171117)), accessed 4 December 2024]. Moreover, [118] showed that it is impossible to establish a unique threshold value for Ni for the entire European continent due to the actual geological conditions. The GEMAS project, which investigated more than 2000 samples in agricultural plowed soils and grazing land across the European continent (but not including data and maps for Romania), led to similar conclusions; the highest Ni concentrations were found in Greece and Serbia, and the highest Cr concentrations were found in northwestern Italy, the southern Balkans, and Greece due to the nature of soil parental materials made up of detritus originating from ophiolites complexes or sedimentary rocks formed by their weathering [119]. These authors [119] propose that guidelines for managing productive land at the European level should be defined for regions with common geological history and common lithologic settings. Studies performed in Hungary [120] for establishing environmental quality standards in the Danube River sediments were based on the solids-water partition coefficient K\({}_{sw}\), similar to the methodology employed in [121], which was later developed and led to the sets of values [122] that were taken and considered as background values in the Romanian legislation [42]. The study [121] warned, however, that the suspended particles and the sediments in the Netherlands have fractions of lutum and organic matter, which are specific to this region and which could be different for other rivers in Europe. Moreover, a recent report on the state of European soils, which included an analysis of the trace elements concentrations in EU agricultural soils based on the LUCAS 2009 database [123], found that if the European Lower Limit Values for trace elements proposed [124] for the Sewage Sludge Directive were to be used all over Europe, one-third of the European agricultural land would exceed these limit values for at least for one trace element, and no sludge could be spread thereafter. Therefore, care should be taken by European countries, including Romania, to adopt reasonable limit values both for sediments and soils, in line with their geological background and, at the same time, aiming to protect human health and preserve water- and soil-related ecosystem services.