Data of polycyclic aromatic hydrocarbons concentration in the Siberian Arctic seas sediments.

Polycyclic Aromatic Hydrocarbons (PAHs) are one of the most dangerous persistent organic pollutants in the Arctic. They have different sources and pathways of entering in to the environment. Because of their lipophilic properties, PAHs can easily accumulate in marine sediments. This work gives a new data about concentration of PAHs in Siberian arctic seas. Sixteen priority PAHs as well as 1- and 2-methylnaphthalenes were analyzed by gas chromatography - tandem mass spectrometry in the twenty-four sediment samples taken from Kara, Laptev and East Siberian Seas in October 2020. The obtained sum concentrations ranged from 31 to 223 ng g-1 with the greatest contribution of phenanthrene, benzo[b]fluoranthene, benzo[k]fluoranthene, as well as naphthalene and its methyl derivatives while the greatest PAH levels were observed in Laptev Sea. The toxic equivalent in benzo[a]pyrene units was from 2.2-18.2 ng g-1. Total organic carbon (TOC) and black carbon (BC) content in arctic were in the ranges of 0.18-1.98 % and 0.03-0.40 %, respectively. The overall PAH level shows negligible harm to the environment.

Polycyclic aromatic hydrocarbons in the Siberian Arctic seas sediments.

Polycyclic Aromatic Hydrocarbons (PAHs) are among the main persistent organic pollutants in the Arcticwhich enter the polar region from lower latitudes by air transport and ocean currents and accumulate in marine sediments. This work represents the first study in 25 years of the least studied and hard-to-reach areas of Siberian arctic seas. Sixteen priority PAHs as well as 1- and 2-methylnaphthalenes were analyzed by gas chromatography - tandem mass spectrometry in the twenty-four sediment samples taken from Kara, Laptev and East Siberian Seas in October 2020. The obtained sum concentrations ranged from 31 to 223 ng/ g with the greatest contribution of phenanthrene, benzo[b]fluoranthene, benzo[k]fluoranthene, as well as naphthalene and its methyl derivatives while the greatest PAH levels were observed in Laptev Sea. No correlations between sum PAH concentration, total organic carbon and black carbon contents were found. The toxic equivalent in benzo[a]pyrene units was from 2.2-18.2 ng/ g that shows the general safe environmental situation in the region. The overall PAH level is comparable with the data obtained in 1990s which indicates a long-term persistence of pollution despite an overall decline in global PAH emissions. The main sources of PAHs involve mainly coal/biomass and liquid fuel combustion with weaker contribution of petroleum sources.

Analysis of the functional group composition of the spruce and birch phloem lignin.

In this article, the functional group composition of the spruce (Pícea ábies) and birch (Bétula péndula) phloem lignin is described. The features of the chemical structure were studied by analyzing dioxane lignin using the elemental analysis, UV-Vis, FT-IR, and 1D NMR spectroscopy. For comparison, samples of xylem dioxane lignin isolated from the corresponding wood species were also analyzed. FT-IR spectroscopy data suggest that the lignins of birch phloem and xylem are similar in chemical structure. However, there are differences in absorption bands in the spectra of spruce dioxane lignin, which indicate the opposite. Quantitative analysis of the functional group composition was performed using 13C and 31P NMR data. It was found that free phenolic hydroxyl groups of catechol and p-hydroxyphenyl types are dominated in the composition of spruce phloem lignin. Birch phloem lignin has a qualitative and quantitative composition of functional groups characteristic of hardwood lignins. However, the content of G-units is greater than S-units, in contrast to the birch xylem lignin, where S-units predominate. The revealed differences are relevant from the point of view of plant physiology. The practical significance of the study is connected with understanding the reactivity of lignins when considering the chemical processing of tree bark.

Comprehensive analysis of the chemical structure of lignin from raspberry stalks (Rubus idaeus L.).

Lignins of non-woody fast-growing plants cause high interest in recent time as a potential source of raw materials for biorefining. Studying of the lignin structure in shrubs will allow obtaining the information about processes of biosynthesis of these plants and developing methods of their delignification for bioprocessing industry. We studied the structure of raspberry dioxane lignin (Rubus idaeus L.) using various spectroscopic methods, including FT-IR and NMR (1D and 2D) for various nuclei. Also, we used gel permeation chromatography and elemental analysis. It is obtained that raspberry dioxane lignin has relatively wide polydispersity, with Mw/Mn = 2.6, and a relatively lower molecular weight (Mw = 5111 g/mol) due to low molecular weight oligolignols. 31P-NMR spectroscopy allowed to obtain that raspberry lignin belongs to GS-type. Due to 13C-NMR we calculated hypothetical empirical formula of the studied lignin and determined the substructures and ether bonds content. S/G ratio of lignin is important parameter for delignification process, and it is equal to 1.19 indicating that lignin rich in S-units will easily degrade even under mild alkaline conditions.

Structural characterization of the lignin from Saxifraga (Saxifraga oppositifolia L.) stems.

As a renewable source of unique aromatic compounds, lignin attracts the attention of many researchers. However, for its successful application, it is necessary to have a clear and accurate idea of its chemical structure. Therefore, it is necessary to expand knowledge about the structure of lignins of various nature using the informative analytical methods. The aim of this study was to characterize the dioxane lignin of the Saxifraga oppositifolia L. - the northernmost angiosperm. The lignin of plants growing in the Arctic zone may differ significantly from other plants, both due to species differences and peculiarities of growing conditions. Studies were conducted on an isolated lignin preparation obtained by the Pepper's method. Analysis of Py-GC/MS data and NMR spectroscopy showed that saxifrage lignin belongs to GH-type. This is evidenced by a significant proportion of p-hydroxyphenyl units (40%), while the content of syringyl units is about 14%. The major substructures of the studied lignin were ß-aryl ether, phenylcoumaran, and resinol. It was found that the γ­carbon of the lignin side chains are partly acetylated, and forms ester bonds with the p-hydroxybenzoate structure. In addition, the NMR spectrum showed a signal of the phenylglycoside evidenced the presence of the lignin-carbohydrate complex.