The contamination of the Lower Danube Basin with trace elements has been the subject of intense study in recent years, with several pollution indices being employed for the assessment of water, soil, and sediment quality. Most pollution indices are calculated by comparing the measured concentration to a reference value, with different values from various sources being used. In this study, the threshold values for trace elements (As, Cd, Cu, Hg, Ni, Pb, and Zn) in Romania were selected based on the median of their concentration in stream sediment from 167 locations, which were carefully selected to be far from contamination sources. The threshold values were established based on a calculation starting from the geochemical concentration presented in the Geochemical Atlas of Romania (scale: 1:3,000,000, developed in 2006 by a collaborative Romanian-German team). By using these thresholds, pollution indices were calculated for nine sampling locations, from which suspended sediment, bottom sediment, and active floodplain sediment samples were collected and analyzed in an accredited laboratory. Most of the selected thresholds were found to be below the limits for sediments established by Romanian legislation, except for Cr and Ni, the higher values of which are consistent with the specific geological background of the country and the broader Balkan region.

This paper presents a set of Ground Penetrating Radar (GPR) data obtained from in situ measurements conducted in four ornamental stone quarries located in Italy (Botticino quarry) and Romania (Ruschita, Carpinis, and Pietroasa quarries). The GPR is a Non-Destructive Testing (NDT) technique that enables the detection and localization of fractures without damage to the surface, among other capabilities. In this study, two instruments of ground-coupled GPR were used to detect and locate the fractures, discontinuities, or weakened zones. The GPR data contains radargrams for discontinuities and fracture detection, besides the geographic location of the measures. For each measurement site, a set of radargrams has been acquired in two orthogonal directions, allowing for a 3D reconstruction of the investigated site.