"Temporal dynamics of anthropogenic contaminants in sediments of the Kongsfjorden-Krossfjorden system (Svalbard, Norway)"

In this study, four marine sediment cores have been collected from the Kongsfjorden-Krossfjorden system (Svalbard, Norway) to evaluate the occurrence and temporal trends of selected legacy and emerging contaminants, discriminating possible contamination sources. Sampling campaigns took place in 2011, with the collection of one core (NYA11_09); and in 2021, with the collection of three cores (NYA21_01, NYA21_03 and NYA21_04). Selected emerging contaminants included organic UV-Filters (UV-Fs) and synthetic fragrances (SFs) analyzed in the core collected in 2011; whereas among the legacy contaminants, polybrominated diphenyl ethers (PBDEs) were analyzed in the three cores collected in 2021. An age-depth model was developed for each core to evaluate the historical deposition of selected contaminants. To the best of our knowledge, this study is the first to examine historical trends of PBDEs in sediment cores from KKS and to simultaneously investigate the deposition of selected organicUV-Fs and SFs in Arctic marine sediments. Chemical analyses were performed including extraction procedure by Pressurized Liquid Extraction (PLE) for both legacy and emerging contaminants, and determination and quantification of selected compounds by gas chromatography-tandem mass spectrometry (GC-MS/MS) for emerging contaminants and gas chromatography-mass spectrometry (GC-MS) for legacy contaminants. From the analyses, 4 out of 7 UV-Fs, 3 out of 6 SFs and 11 out of 38 PBDEs have been detected in the sediment cores. Among the UV-Fs detected, there were: 4-MBC (Enzacamene), EHMC (Octinoxate), EHS (Octisalate) and HMS (Homosalate). Among the SFs detected, there were: HHCB (Galaxolide), AHTN (Tonalide) and OTNE (Iso-E Super). The total concentration of Σ4UV-Fs and Σ3SFs in the core NYA11_09 ranged from <LOD to 10.4 ng g -1 d.w. and <LOD to 6.4 ng g -1 d.w., respectively. EHMC and OTNE were the most abundant compounds. Among the PBDEs congeners detected, there were: BDE-28, BDE-47, BDE-49, BDE-71, BDE-99, BDE-100, BDE-119, BDE-116, BDE-173+190 and BDE-183. The total concentrations of Σ11PBDEs ranged from <LOD to 15.33, <LOD to 3.30 and 0.12 to 6.01 ng g−1 d.w. in the cores NYA21_01, NYA21_03 and NYA21_04, respectively. Penta- and hepta-BDEs were the most abundant PBDE homologues in all three sediment cores. After dating, historical trends were evaluated. Regarding the legacy contaminants, total PBDEs concentrations in all three sediment cores began to increase noticeably from late 1970s-early 1980s, until a peak concentration around mid-2000s, declining thereafter. This declining trend might reflect the disposal of some technical PBDEs mixtures occurred in the global market in the early 2000s. Regarding the emerging contaminants, total UV-Fs and SFs concentrations showed a general increasing trend from the early 1970s and early 1980s respectively, reaching a peak concentration around late 1990s-early 2000s, declining thereafter. This declining trend could probably be related to the changes in the sewage pipe system that took place in 2006, resulting in the effluents being discharged further out into the fjord and no longer close to the village of Ny-Ålesund. However, different sources are responsible for environmental contamination of the study area, including long- and medium-range transport, anthropogenic activities and climate-change related ‘secondary sources’. Marine sediments constitute an important sink for organic contaminants, largely due to their settling and deposition associated with the presence of organic matter. These results showed consistency with manufacturing and use trends for selected legacy and emerging contaminants, confirming that sediment cores represent valuable natural archives to better understand the sources and reconstruct the historical deposition of substances of anthropogenic origin.