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Chemical Composition and Potential Environmental Impacts of Water-Soluble Polar Crude Oil Components Inferred from ESI FT-ICR MS.

Liu Y, Kujawinski EB - PLoS ONE (2015)

Bottom Line: Our results show that compounds with higher heteroatom (N, S, O) to carbon ratios (NSO:C) than the parent oil were selectively partitioned into seawater in both fractions, reflecting the influence of polarity on aqueous solubility.WAF and WSF were compositionally distinct, with unique distributions of compounds across a range of hydrophobicity.We use an empirical model to estimate hydrophobicity character for individual molecules within these complex mixtures and provide an estimate of the potential environmental impacts of different crude oil components.

View Article: PubMed Central - PubMed

Affiliation: Department of Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543, United States of America.

ABSTRACT
Polar petroleum components enter marine environments through oil spills and natural seepages each year. Lately, they are receiving increased attention due to their potential toxicity to marine organisms and persistence in the environment. We conducted a laboratory experiment and employed state-of-the-art Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to characterize the polar petroleum components within two operationally-defined seawater fractions: the water-soluble fraction (WSF), which includes only water-soluble molecules, and the water-accommodated fraction (WAF), which includes WSF and microscopic oil droplets. Our results show that compounds with higher heteroatom (N, S, O) to carbon ratios (NSO:C) than the parent oil were selectively partitioned into seawater in both fractions, reflecting the influence of polarity on aqueous solubility. WAF and WSF were compositionally distinct, with unique distributions of compounds across a range of hydrophobicity. These compositional differences will likely result in disparate impacts on environmental health and organismal toxicity, and thus highlight the need to distinguish between these often-interchangeable terminologies in toxicology studies. We use an empirical model to estimate hydrophobicity character for individual molecules within these complex mixtures and provide an estimate of the potential environmental impacts of different crude oil components.

No MeSH data available.


Related in: MedlinePlus

Carbon number vs. nominal mass plot of the DCM 1 extracts of the water-accommodated fraction (WAF; left) and water-soluble fraction (WSF; right) from the VSW treatment.Each m/z value with an assigned elemental formula is represented by a dot on the figure. The size of each dot corresponds to relative peak height. Components in parent oil are plotted in grey to serve as reference. Color bar indicates ratio of total heteroatoms to carbon atoms (NSO:C).
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pone.0136376.g002: Carbon number vs. nominal mass plot of the DCM 1 extracts of the water-accommodated fraction (WAF; left) and water-soluble fraction (WSF; right) from the VSW treatment.Each m/z value with an assigned elemental formula is represented by a dot on the figure. The size of each dot corresponds to relative peak height. Components in parent oil are plotted in grey to serve as reference. Color bar indicates ratio of total heteroatoms to carbon atoms (NSO:C).

Mentions: The DCM 1, DCM 2 and DCM-PPL extracts of the aqueous samples (i.e. WAF and WSF) are compositionally different from the parent crude oil (Fig 1 and S1 Fig). Furthermore, WAF samples are compositionally distinct from their WSF counterparts within the DCM 1 and DCM 2 extracts (Figs 1, 2 and 3; S1 and S3 Figs). We conclude that filter-adsorption, therefore, had a significant impact on oil-derived lipophilic compound composition in the aqueous phase. In contrast, filtration did not noticeably affect the very polar fractions (i.e. DCM-PPL) of WSF due to their hydrophilic nature (Fig 1 and S1 Fig). Between the VSW and VSWE treatments, no significant compositional differences were observed between pairs of extracts (e.g. DCM 1’s), suggesting that lipophilic DOM constituents removed by DCM do not noticeably affect the solubility of crude oil-derived polar compounds (Fig 1; S1 Fig and S1 Table).


Chemical Composition and Potential Environmental Impacts of Water-Soluble Polar Crude Oil Components Inferred from ESI FT-ICR MS.

Liu Y, Kujawinski EB - PLoS ONE (2015)

Carbon number vs. nominal mass plot of the DCM 1 extracts of the water-accommodated fraction (WAF; left) and water-soluble fraction (WSF; right) from the VSW treatment.Each m/z value with an assigned elemental formula is represented by a dot on the figure. The size of each dot corresponds to relative peak height. Components in parent oil are plotted in grey to serve as reference. Color bar indicates ratio of total heteroatoms to carbon atoms (NSO:C).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556654&req=5

pone.0136376.g002: Carbon number vs. nominal mass plot of the DCM 1 extracts of the water-accommodated fraction (WAF; left) and water-soluble fraction (WSF; right) from the VSW treatment.Each m/z value with an assigned elemental formula is represented by a dot on the figure. The size of each dot corresponds to relative peak height. Components in parent oil are plotted in grey to serve as reference. Color bar indicates ratio of total heteroatoms to carbon atoms (NSO:C).
Mentions: The DCM 1, DCM 2 and DCM-PPL extracts of the aqueous samples (i.e. WAF and WSF) are compositionally different from the parent crude oil (Fig 1 and S1 Fig). Furthermore, WAF samples are compositionally distinct from their WSF counterparts within the DCM 1 and DCM 2 extracts (Figs 1, 2 and 3; S1 and S3 Figs). We conclude that filter-adsorption, therefore, had a significant impact on oil-derived lipophilic compound composition in the aqueous phase. In contrast, filtration did not noticeably affect the very polar fractions (i.e. DCM-PPL) of WSF due to their hydrophilic nature (Fig 1 and S1 Fig). Between the VSW and VSWE treatments, no significant compositional differences were observed between pairs of extracts (e.g. DCM 1’s), suggesting that lipophilic DOM constituents removed by DCM do not noticeably affect the solubility of crude oil-derived polar compounds (Fig 1; S1 Fig and S1 Table).

Bottom Line: Our results show that compounds with higher heteroatom (N, S, O) to carbon ratios (NSO:C) than the parent oil were selectively partitioned into seawater in both fractions, reflecting the influence of polarity on aqueous solubility.WAF and WSF were compositionally distinct, with unique distributions of compounds across a range of hydrophobicity.We use an empirical model to estimate hydrophobicity character for individual molecules within these complex mixtures and provide an estimate of the potential environmental impacts of different crude oil components.

View Article: PubMed Central - PubMed

Affiliation: Department of Marine Chemistry & Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, 02543, United States of America.

ABSTRACT
Polar petroleum components enter marine environments through oil spills and natural seepages each year. Lately, they are receiving increased attention due to their potential toxicity to marine organisms and persistence in the environment. We conducted a laboratory experiment and employed state-of-the-art Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to characterize the polar petroleum components within two operationally-defined seawater fractions: the water-soluble fraction (WSF), which includes only water-soluble molecules, and the water-accommodated fraction (WAF), which includes WSF and microscopic oil droplets. Our results show that compounds with higher heteroatom (N, S, O) to carbon ratios (NSO:C) than the parent oil were selectively partitioned into seawater in both fractions, reflecting the influence of polarity on aqueous solubility. WAF and WSF were compositionally distinct, with unique distributions of compounds across a range of hydrophobicity. These compositional differences will likely result in disparate impacts on environmental health and organismal toxicity, and thus highlight the need to distinguish between these often-interchangeable terminologies in toxicology studies. We use an empirical model to estimate hydrophobicity character for individual molecules within these complex mixtures and provide an estimate of the potential environmental impacts of different crude oil components.

No MeSH data available.


Related in: MedlinePlus