Differences in acquisition of environmental data in strongly impacted marine sediments using gravity and vibro corers: the case-study of Augusta harbor (Eastern Sicily, Italy)

Sediment cores are used to reconstruct the chronological evolution of contamination in impacted areas while deep core levels may be considered as reference conditions for the assessment of environmental status. For this purpose, the collection of undisturbed cores is essential. Vibro and gravity corers are the most used devices for environmental research. In this study, chemical (Ba, Hg and PCBs) and grain size data obtained by means of gravity (SW-104) and vibro (Rossfelder®) corer from 3 stations of the heavily contaminated Augusta harbor (Sicily, Italy) were considered. Their vertical profiles were compared considering the different technical characteristics of corers, in order to highlight differences in data acquisition. Results showed that, for areas characterized by high sedimentation rates, the vibrocorer is the best choice for the higher penetration capacity. No significant differences were recognized for sediment compaction and potential downward drag of the contaminants.</p

A comparison between Laser Granulometer and Sedigraph in grain size analysis of marine sediments

A total of 24 sediment samples with wide dimensional, mineralogical and compositional range were considered, collected from 5 Italian coastal marine sites. The fine fraction (<63 μm) was analyzed using Laser Granulometer (LG) and X-ray Sedigraph (XS) in order to compare data and highlight potential differences. The unexpected variable sandy fraction in nearly all the samples was attributed to clay mineral aggregates. The highest sand percentages detected by XS were attributed to local compositional sediment features. An increase of 15–25% of clay in samples analyzed by XS was attributed to the different working principles of the considered devices. Nevertheless, final results succeeded in characterizing sediment texture and distribution as a function of water depth. In conclusion, it's important to select the analytical instrument according to the characteristics of sediments, to adjust the density of media solution for XS analysis, and to prevent aggregates formation for both XS and LG