Abstract

Nickel and vanadyl porphyrins belong to the so-called fossil geo- or sedimentary porphyrins. They occur in different types of organic matter-rich sediments but mostly occur in crude oils and their source rocks, oil shales, coals, and oil sands. In this study, we aimed to understand the process of bacterial transformation of geoporphyrins occurring in the subsurface shale rock (Fore-Sudetic Monocline, SW Poland). We studied these transformations in rock samples directly obtained from the field; in rock samples treated with bacterial strain isolated from shale rock (strain LM27) in the laboratory; and using synthetic nickel and vanadyl porphyrins treated with LM27. Our results demonstrate the following: (i) cleavage and/or degradation of aliphatic and aromatic substituents of porphyrins; (ii) degradation of porphyrin (tetrapyrrole) ring; (iii) formation of organic compounds containing 1, 2, or 3 pyrrole rings; (iv) formation of nickel- or vanadium-containing organic compounds; and (v) mobilization of nickel and vanadium. Our results also showed that the described bacterial processes change the composition and content of geoporphyrins, composition of extractable organic matter, as well as nickel and vanadium content in shale rock.

Highlights

  • Tetrapyrrole pigments such as chlorophyll and bacteriochlorophylls, as well as heme, are the most abundant and evolutionarily amongst the oldest pigments on the earth (Gueneli et al, 2018)

  • We have shown that the community of microorganisms inhabiting the shale rocks were responsible for the oxidation and dehydrogenation of kerogen and for the mobilization of fossil organic carbon in the oxidized form (Stasiuk et al, 2017; Włodarczyk et al, 2018)

  • Further we investigated whether these processes affect the distribution and/or transformation of nickel and vanadyl geoporphyrins, and how these porphyrin transformations is affecting are potentially linked with the composition of the extractable organic matter

Read more

Summary

Introduction

Tetrapyrrole pigments such as chlorophyll and bacteriochlorophylls, as well as heme, are the most abundant and evolutionarily amongst the oldest pigments on the earth (Gueneli et al, 2018). These compounds are the biological precursors of sedimentary porphyrins, which are called geoporphyrins or petroporphyrins. These compounds occur in fossil fuels and asphalts as well as in oil shales and their associated source rocks dominantly as nickel(II) and vanadyl (oxovanadium(IV); VO(IV)) metal complexes.

Objectives
Methods
Results
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call