Polycyclic aromatic hydrocarbons in permafrost peatlands

Alexander Pastukhov,Sergey Loiko,Dmitry Kaverin

doi:10.1038/s41598-021-98384-z

Abstract

The concentrations of 15 individual PAHs in 93 peat cores have been determined by using high-performance liquid chromatography methods. In the profile the qualitative and quantitative composition of PAHs was non-uniform estimated in a wide range: from 112 to 3673 ng/g with mean 1214 ± 794 ng/g. Among 15 identified individual PAHs, the main contribution to their total amount was made by heavy highly condensed PAHs in the Eastern European peat plateaus, in particular, 6-nuclear benzo[ghi]perylene (1021 ± 707 ng/g), whereas in West Siberian permafrost peatlands, light PAHs were dominating, mostly naphthalene and phenanthrene (211 ± 87 and 64 ± 25 ng/g, respectively). The grass-equisetum peat contained the maximum of heavy PAHs and the dwarf shrub-grass—the minimum. In grass-dwarf shrub, grass-moss and moss peat, the share of 2-nuclear PAHs was most significant: naphthalene and fluorene, as well as 6-nuclear benzo[ghi]perylene. The presence of benzo[ghi]perylene in the entire peat strata, including its permafrost layer, was a marker of the anaerobic conditions that persisted throughout the Holocene and they were necessary for the synthesis of this compound.

Highlights

The concentrations of 15 individual Polycyclic aromatic hydrocarbons (PAHs) in 93 peat cores have been determined by using highperformance liquid chromatography methods
The results reported here, based on peat plateaus in European Northeast, confirm our previous findings that the PAH concentration is much lower in the active layer of peat plateaus, than in those in permafrost, which indicates the onset of aerobic conditions and ongoing biodegradation[29]
In East European peat plateaus, the main contribution to the total PAHs is made by 6-nuclear benzo[ghi]perylene, the content of which in some layers exceeds the upper determination limit—2000 ng/g; the concentrations of heavy PAHs are by 4.4 ± 2.8 times higher than those of light polyarenes

Summary

Introduction

The concentrations of 15 individual PAHs in 93 peat cores have been determined by using highperformance liquid chromatography methods. To identify the plant groups that compose peat layers, the analysis of different chemical parameters is widely applied: the composition of humic substances and low molecular weight organic compounds—aliphatic compounds, phenols, n-alkanes, alcohols, carbohydrates, low molecular weight organic a cids[14,15,16,17,18,19,20,21,22,23,24] These markers were used to analyze soil organic carbon of permafrost peatlands in the tundra and forest-tundra, located in zones of continuous and massive island permafrost d istribution[25,26,27,28]. The composition of PAHs is considered as one of the indicators of peat plateaus/thermokarst complexes genesis29. 6-nuclear benz[ghi]perylene as the most immobile and stable in an anaerobic environment, but relatively rapidly decomposed under aerobic conditions, can be a sufficiently reliable bioindicator of the persistence of organic matter during the Holocene and in the future, even under permafrost thawing, because the anaerobic conditions will persist

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Discussion

Conclusion