Study of 10Be in the sediments from the Krossfjorden and Kongsfjorden Fjord System, Svalbard

Exploring bacterial diversity in Arctic fjord sediments: a 16S rRNA-based metabarcoding portrait

The frosty polar environment houses diverse habitats mostly driven by psychrophilic and psychrotolerant microbes. Along with traditional cultivation methods, next-generation sequencing technologies have become common for exploring microbial communities from various extreme environments. Investigations on glaciers, ice sheets, ponds, lakes, etc. have revealed the existence of numerous microorganisms while details of microbial communities in the Arctic fjords remain incomplete. The current study focuses on understanding the bacterial diversity in two Arctic fjord sediments employing the 16S rRNA gene metabarcoding and its comparison with previous studies from various Arctic habitats. The study revealed that Proteobacteria was the dominant phylum from both the fjord samples followed by Bacteroidetes, Planctomycetes, Firmicutes, Actinobacteria, Cyanobacteria, Chloroflexi and Chlamydiae. A significant proportion of unclassified reads derived from bacteria was also detected. Psychrobacter, Pseudomonas, Acinetobacter, Aeromonas, Photobacterium, Flavobacterium, Gramella and Shewanella were the major genera in both the fjord sediments. The above findings were confirmed by the comparative analysis of fjord metadata with the previously reported (secondary metadata) Arctic samples. This study demonstrated the potential of 16S rRNA gene metabarcoding in resolving bacterial composition and diversity thereby providing new in situ insights into Arctic fjord systems.

A sensitive vesicle mediated dispersive liquid-liquid microextraction of parts per quadrillion levels of beryllium from seawater samples prior to graphite furnace atomic absorption spectrometry determination

A rapid and highly sensitive vesicle mediated dispersive liquid-liquid microextraction procedure is developed for the determination of parts per quadrillion level of beryllium in seawater and air filter samples for providing its natural background and contamination levels. In this procedure, dioctylsulfosuccinate, an anionic vesicular surfactant and acetylacetone are used as dispersing and chelating agents, respectively. At pH > 9.5, beryllium forms hydrophobic beryllium-acetylacetonate complex spontaneously at room temperature. This complex is selectively filled into the vesicular cavities of dioctylsulfosuccinate and is extracted into small chloroform phase from bulk aqueous phase. The beryllium present in the chloroform phase is back extracted with dilute nitric acid and is analyzed by graphite furnace atomic absorption spectrometry. This method is applied to groundwater, seawater, coal fly ash, air filter and sea sludge samples. Under the optimized conditions, the limit of detection, limit of quantification and linear dynamic range are 10 fg mL^-1, 33 fg mL^-1 and 40-500 fg mL^-1 for seawater; 0.15 ng g^-1, 0.5 ng g^-1 and 0.4-4 ng g^-1 for air filter and 1.5 ng g^-1, 0.39 ng g^-1 and 0.4-4 ng g^-1 for coal fly ash, respectively. For 1 L seawater sample an enrichment factor of 954 is achieved. Coefficient of determination (R²) is found to be 0.997. The recoveries are in the range of 94-105% at 200-500 fg mL^-1. The relative standard deviations are 20%, 11%, 8% for ppq, ppt and ppb levels of Be, respectively. The accuracy of the procedure is verified by analyzing NIST SRMs 1640 and 1640a trace elements in natural water.

Source, mobility, and bioavailability of metals in fjord sediments of Krossfjord-Kongsfjord system, Arctic, Svalbard

Krossfjord-Kongsfjord system situated on the west coast of Svalbard archipelago is an ideal location to investigate the impacts of climate change on the environment. As a consequence of global warming, metal concentrations in the Arctic region are increasing due to permafrost melting and changes in biological processes. Therefore, the fjord sediments were studied for identification of provenance, mobility, bioavailability, and potential toxicity of metals in the fjord environment. Finer sediments and organic matter were found to be higher away from the glacier outlets, while coarser sediments were found to be higher near the glacier head. Illite, kaolinite, and chlorite constituted the clay mineral assemblage which had slightly influenced the metal distributions. The variations in metal abundance were attributed largely to the glacial activity along with the influence of Atlantic water mass in western Spitsbergen. Fjord system received sediment from the weathering of rocks indicating an input of terrigenous material. Comparison of metals in bulk sediment with Arctic sediment quality guidelines (ASQGs) showed that Zn and Cu were enriched in the sediment. However, to avoid the overestimation of the risk associated, fractionation of the metals was carried out which revealed higher Mn and Co in labile phases that pose a considerable risk to the biota.