The recent intensification of energy resource exploration and human activities in the Barents Sea (BS) requires a more thorough assessment of the natural and anthropogenic impact of hydrocarbons on ...the environment. We analyzed a wide set of sensitive indicators, including hydrocarbon molecular markers and organic matter (OM) maturity parameters in the Holocene sediments from three regions of the BS: the Kola-Kanin Monocline (KKM), the Svalbard shelf, and the Shtokman gas-condensate field (GCF). An increase in pyrogenic polycyclic aromatic hydrocarbons toward the core surface traces the intensification of anthropogenic contamination in the KKM region during last century. An input of highly mature OM from the eroded coal rocks of Barentsburg were confirmed by comparison of biomarker distribution in sediments and coals. An increase in biogenic hopanes and hopenes content down-core, and a crude-oil stage of OM maturity in surface sediments of the Shtokman GCF attests to hydrocarbons migration from subsurface strata.
•Recent sediments from Svalbard Shelf, Shtokman and Kola-Kanin Monocline areas studied•Significant variation in hydrocarbons genesis in the Barents Sea sediments detected•Svalbard sediments show the highest level of organic matter maturity.•In the Shtokman area, molecular marker distributions indicated hydrocarbon migration•Sediment PAH composition of Kola-Kanin Monocline suggested anthropogenic impact.
Growing anthropogenic activity in the Arctic, especially near regional municipal and transportation hubs, threatens coastal environments with significant changes and contamination. A detailed study ...of a wide set of organic-geochemical proxies in surface and subsurface sediments and soils around the typical urbanized Arctic area (Tromsø, Norway) was performed to investigate natural and anthropogenic input of hydrocarbons. The sites were located close to main areas of human activity and differed in the level of anthropogenic pressure: oil terminal, boat harbor and recreation beach zone in the city center, and a remote, conditionally-clean area. The samples from each site were collected along four subtidal – intertidal – supratidal transects. GC–MS data on the distribution of more than 110 compounds were obtained including n-alkanes, isoprenoids, terpanes, parent polycyclic aromatic hydrocarbons (PAHs), and alkyl PAHs. Organic matter embedded in a mineral matrix was more thermally mature than its fresh non-bound fraction. Biomarker distribution and diagnostic ratios attested to the predominantly local origin of near-shore organic matter formation (phytoplankton, algae, high foliar plants, grass). PAH composition revealed a significant input of pyrogenic components from liquid and solid fuel combustion to the surface coarse-grained sediments. Background bacterial activity was evidenced by the high content of biohopanes and hopenes in less polluted sediments and soils. The presence of an unresolved complex mixture and even n-alkanes in sediment profiles from the most polluted sites attested to the active biodegradation that, together with the erosion of the upper layers by tidal currents, reduces the toxic compound penetration deeper into the sediments.
•Organic matter in intertidal deposits of the urbanized Arctic area was studied.•Organic matter bonded with the mineral matrix is of local origin and highly mature.•Variations in organic-geochemical proxies attest to recent human impact.•Contaminants accumulate predominantly in the surface coarse-grained sediments.•Biomarker composition evidences biodegradation process in polluted sites.
Coastal marine ecosystems in the Arctic are extremely vulnerable to human activities associated with oil and gas exploration, transportation and processing, and with industrial and urban development. ...The effects of complex pollutant mixtures interact with environmental factors. Here we assessed the effects of two anthropogenic and one natural factor on the reproduction, development and adult shell shape of the intertidal ovoviviparous gastropod Littorina saxatilis at 12 sites in the Barents and Norwegian Seas. The stressors studied were toxicity equivalency (TEQ) of the polycyclic aromatic hydrocarbons (PAH), the proximity of the site to urban/industrial locations as a proxy for urban pollution, and salinity. Total fecundity of the snails decreased at sites with low salinity but was not affected by PAH pollution. Allometric relationships of L. saxatilis shell shape varied between sites depending on the proximity of urban/industrial locations; the intrapopulation morphological disparity increased near urban sites. The frequency of abnormal embryos per brood and the incidence of females with abnormal embryos in the brood pouch increased at urban sites, especially under conditions of low salinity, but was unrelated to PAH pollution. Monte Carlo simulation showed that the registered embryotoxic effect of the proximity to urban/industrial locations was unlikely to result in a significant reduction of the population recruitment of L. saxatilis due to the high fecundity of these snails. Elucidation of the mechanisms of low sensitivity of L. saxatilis to PAHs in concentrations registered in our study and identification of the cause of embryotoxic effects associated with the proximity of urban/industrial locations are promising directions of further studies. Our results highlight the importance of considering multiple stressors when assessing anthropogenic impacts on coastal systems. We show that L. saxatilis can be an informative indicator of coastal urban pollution across its wide distribution range.
•Effects of urban proximity, hydrocarbon pollution and salinity are described.•Reproduction, development and shape of Littorina saxatilis snails are used as a model.•Fecundity of L. saxatilis depends on salinity but not on PAH or urban proximity.•Frequency of abnormal embryos depends on salinity and urban proximity but not on PAH.•Adult shell shape morphological disparity is higher at urban sites.
