Higher plant n-alkane average chain length as an indicator of petrogenic hydrocarbon contamination in marine sediments

Leaf wax n-alkanes are well known higher plant biomarkers. These molecules are widely found in geological archives, where their concentration, average chain length (ACL) and isotopic composition (&#948;13Calkanes and &#948;2Halkanes) serve as proxies for changes in continental vegetation and hydroclimate. While mechanistic relationships of these proxies with climate and vegetation are relatively well understood, little is known about the transport of those biomarkers into geological archives. In marine sedimentary records, leaf wax biomarkers are often interpreted to represent the contiguous continental catchments, but few studies have examined the fidelity with which n-alkanes in marine sediments record the corresponding continental conditions.Here we assess the variability of n-alkane composition in terrestrial and marine sediments from 26&#176;S to 41&#176;S along the Chilean coast. The sample sites are located along a strong vegetation and precipitation gradient, with precipitation ranging from 25 to 2300 mm/yr. We evaluate riverbed sediments from twenty catchments, draining the western slopes of the Andes to the Pacific Ocean and compare the values to the ones of 19 samples from marine surface sediments recovered directly offshore each catchment.The correspondence between terrestrial and marine n-alkanes signals changes along the precipitation gradient. Where precipitation rates range between 100 to 500 mm/yr, ACL and &#948;2Halkanes values agree well between continental and adjacent marine sediments. At precipitation rates below 100 mm/yr, ACL and &#948;2Halkanes values recorded in marine sediments are consistently lower than the ones found in continental sediments. At precipitation rates higher than 500 mm/yr, ACL and &#948;2Halkanes values registered in marine sediments are consistently higher than in the adjacent catchments.Multiple factors, including mixing of sediment from different sources along the transport pathway from continent to ocean or variability in catchment storage capacity, likely cause marine n-alkane composition to be offset from their terrestrial source. Nevertheless, the consistent change in behavior along the gradient suggest that precipitation is the dominant factor on the transmission of n-alkane signals along the sedimentary routing systems of the study area. Moreover, since correspondence decreases at high and low precipitation, our data suggest that the sensitivity of the leaf wax biomarker proxy in marine archives towards hydrological change may be subdued due to sedimentary integration. This may have implications for quantitative interpretations derived from n-alkanes and their isotopes in marine paleorecords.

Download Full-text

Röntgenbeugungsuntersuchung an geschmolzenem Selen und Tellur sowie an Legierungen des Systems Selen—Tellur/ X-ray Diffraction Study of Molten Selenium, and Tellurium and of Molten Selenium — Tellurium-Alloys

Zeitschrift für Naturforschung A ◽

10.1515/zna-1975-1220 ◽

1975 ◽

Vol 30 (12) ◽

pp. 1633-1639 ◽

Cited By ~ 4

Author(s):

W. Hoyer ◽

E. Thomas ◽

M. Wobst

Keyword(s):

Chain Length ◽

Short Range ◽

Short Range Order ◽

Coordination Shell ◽

Range Order ◽

Average Chain Length ◽

X Ray Diffraction ◽

Coordination Numbers ◽

Nearest Neighbours ◽

Increasing Temperature

Abstract At temperatures just above the melting point molten Selenium seems to be a mixture of long chains and eight-membered rings. With increasing temperature the number of rings and the average chain length decrease. At 460 °C the average chain length lies in the range of 10 atoms.In a slightly supercooled Tellurium-melt the number of first neighbours is two. The atoms are arranged in chains. Selenium rich Se-Te-alloy-melts are built up of mixed chains. It seems to be possible, that a smaller part of atoms forms Se6Te2 rings. At Tellurium concentrations higher than approximately 50 at.-% the chainlike structure with two next nearest neighbours changes to a disturbed Arsen-like short range order. The number of electrons in the first coordination shell, the short range order parameter introduced by Cowley and the partial coordination numbers show that Se-Te-alloys are of the "solution system" type, but in the whole concentration range for each atom there is a tendency to have "strange coordination".

Download Full-text

Prenylation of Saccharomyces cerevisiae Chs4p Affects Chitin Synthase III Activity and Chitin Chain Length

Eukaryotic Cell ◽

10.1128/ec.00203-06 ◽

2006 ◽

Vol 6 (2) ◽

pp. 328-336 ◽

Cited By ~ 13

Author(s):

Kariona A. Grabińska ◽

Paula Magnelli ◽

Phillips W. Robbins

Keyword(s):

Saccharomyces Cerevisiae ◽

Chain Length ◽

Attachment Site ◽

Chitin Synthase ◽

Yeast Cells ◽

Average Chain Length ◽

Calcofluor White ◽

Protein Factor

ABSTRACT Chs4p (Cal2/Csd4/Skt5) was identified as a protein factor physically interacting with Chs3p, the catalytic subunit of chitin synthase III (CSIII), and is indispensable for its enzymatic activity in vivo. Chs4p contains a putative farnesyl attachment site at the C-terminal end (CVIM motif) conserved in Chs4p of Saccharomyces cerevisiae and other fungi. Several previous reports questioned the role of Chs4p prenylation in chitin biosynthesis. In this study we reinvestigated the function of Chs4p prenylation. We provide evidence that Chs4p is farnesylated by showing that purified Chs4p is recognized by anti-farnesyl antibody and is a substrate for farnesyl transferase (FTase) in vitro and that inactivation of FTase increases the amount of unmodified Chs4p in yeast cells. We demonstrate that abolition of Chs4p prenylation causes a ∼60% decrease in CSIII activity, which is correlated with a ∼30% decrease in chitin content and with increased resistance to the chitin binding compound calcofluor white. Furthermore, we show that lack of Chs4p prenylation decreases the average chain length of the chitin polymer. Prenylation of Chs4p, however, is not a factor that mediates plasma membrane association of the protein. Our results provide evidence that the prenyl moiety attached to Chs4p is a factor modulating the activity of CSIII both in vivo and in vitro.

Download Full-text

Bacterial Community Response to Hydrocarbon Contamination in Soils and Marine Sediments: A Critical Review of Case Studies

Microbial Ecotoxicology ◽

10.1007/978-3-319-61795-4_9 ◽

2017 ◽

pp. 185-226 ◽

Cited By ~ 1

Author(s):

Elpiniki Vandera ◽

Anna I. Koukkou

Keyword(s):

Bacterial Community ◽

Case Studies ◽

Marine Sediments ◽

Critical Review ◽

Community Response ◽

Hydrocarbon Contamination

Download Full-text

Nonacosan-10-ol and n-Alkanes in Leaves of Pinus pinaster

Natural Product Communications ◽

10.1177/1934578x20926073 ◽

2020 ◽

Vol 15 (5) ◽

pp. 1934578X2092607

Author(s):

Biljana Nikolić ◽

Marina Todosijević ◽

Iris Đorđević ◽

Jovana Stanković ◽

Zorica S. Mitić ◽

...

Keyword(s):

Chain Length ◽

Pinus Pinaster ◽

Cuticular Wax ◽

Short Chain ◽

Average Chain Length ◽

Carbon Preference Index ◽

Preference Index ◽

Long Chain

In leaf cuticular wax of Pinus pinaster, content of nonacosan-10-ol is high (77.1% on average). n-Alkanes ranged from C18 to C35 with the most dominant C29 (24.8%). The carbon preference index (CPItotal) ranged from 3.1 to 5.6 (4.0 on average), while the average chain length (ACLtotal) ranged from 14.0 to 17.0 (14.8 on average). Long-chain n-alkanes ( n-C25-35) strongly dominated (80.1%) over middle-chain ( n-C21-24 = 18.9%) and short-chain ( n -C18-20 = 0.9%) n-alkanes.

Download Full-text

Glycogen with short average chain length enhances bacterial durability

The Science of Nature ◽

10.1007/s00114-011-0832-x ◽

2011 ◽

Vol 98 (9) ◽

pp. 719-729 ◽

Cited By ~ 37

Author(s):

Liang Wang ◽

Michael J. Wise

Keyword(s):

Chain Length ◽

Average Chain Length

Download Full-text

Organic-matter quality of deep permafrost carbon – a study from Arctic Siberia

Biogeosciences ◽

10.5194/bg-12-2227-2015 ◽

2015 ◽

Vol 12 (7) ◽

pp. 2227-2245 ◽

Cited By ~ 46

Author(s):

J. Strauss ◽

L. Schirrmeister ◽

K. Mangelsdorf ◽

L. Eichhorn ◽

S. Wetterich ◽

...

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Stable Carbon Isotopes ◽

Average Chain Length ◽

Frozen Ground ◽

Higher Plant ◽

Organic Matter Quality ◽

Microbial Decomposition ◽

Geochemical Parameters

Abstract. The organic-carbon (OC) pool accumulated in Arctic permafrost (perennially frozen ground) equals the carbon stored in the modern atmosphere. To give an idea of how Yedoma region permafrost could respond under future climatic warming, we conducted a study to quantify the organic-matter quality (here defined as the intrinsic potential to be further transformed, decomposed, and mineralized) of late Pleistocene (Yedoma) and Holocene (thermokarst) deposits on the Buor-Khaya Peninsula, northeast Siberia. The objective of this study was to develop a stratigraphic classified organic-matter quality characterization. For this purpose the degree of organic-matter decomposition was estimated by using a multiproxy approach. We applied sedimentological (grain-size analyses, bulk density, ice content) and geochemical parameters (total OC, stable carbon isotopes (δ13C), total organic carbon : nitrogen (C / N) ratios) as well as lipid biomarkers (n-alkanes, n-fatty acids, hopanes, triterpenoids, and biomarker indices, i.e., average chain length, carbon preference index (CPI), and higher-plant fatty-acid index (HPFA)). Our results show that the Yedoma and thermokarst organic-matter qualities for further decomposition exhibit no obvious degradation–depth trend. Relatively, the C / N and δ13C values and the HPFA index show a significantly better preservation of the organic matter stored in thermokarst deposits compared to Yedoma deposits. The CPI data suggest less degradation of the organic matter from both deposits, with a higher value for Yedoma organic matter. As the interquartile ranges of the proxies mostly overlap, we interpret this as indicating comparable quality for further decomposition for both kinds of deposits with likely better thermokarst organic-matter quality. Supported by principal component analyses, the sediment parameters and quality proxies of Yedoma and thermokarst deposits could not be unambiguously separated from each other. This revealed that the organic-matter vulnerability is heterogeneous and depends on different decomposition trajectories and the previous decomposition and preservation history. Elucidating this was one of the major new contributions of our multiproxy study. With the addition of biomarker data, it was possible to show that permafrost organic-matter degradation likely occurs via a combination of (uncompleted) degradation cycles or a cascade of degradation steps rather than as a linear function of age or sediment facies. We conclude that the amount of organic matter in the studied sediments is high for mineral soils and of good quality and therefore susceptible to future decomposition. The lack of depth trends shows that permafrost acts like a giant freezer, preserving the constant quality of ancient organic matter. When undecomposed Yedoma organic matter is mobilized via thermokarst processes, the fate of this carbon depends largely on the environmental conditions; the carbon could be preserved in an undecomposed state till refreezing occurs. If modern input has occurred, thermokarst organic matter could be of a better quality for future microbial decomposition than that found in Yedoma deposits.

Download Full-text