Production of n-alkyl lipids in living plants and implications for the geologic past

Details Production of n-alkyl lipids in living plants and implications for the geologic past Production of n-alkyl lipids in living plants and implications for the geologic past

Dec 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011gecoa..75.7472d&link_type=abstract

Geochimica et Cosmochimica Acta, Volume 75, Issue 23, p. 7472-7485.

Computer Science

2

Scientific paper

Leaf waxes (i.e., n-alkyl lipids or n-alkanes) are land-plant biomarkers widely used to reconstruct changes in climate and the carbon isotopic composition of the atmosphere. There is little information available, however, on how the production of leaf waxes by different kinds of plants might influence the abundance and isotopic composition of n-alkanes in sedimentary archives. This lack of information increases uncertainty in interpreting n-alkyl lipid abundance and δ13C signals in ancient settings. We provide here n-alkyl abundance distributions and carbon isotope fractionation data for deciduous and evergreen angiosperm and gymnosperm leaves from 46 tree species, representing 24 families. n-Alkane abundances are significantly higher in angiosperms than gymnosperms; many of the gymnosperm species investigated did not produce any n-alkanes. On average, deciduous angiosperms produce 200 times more n-alkanes than deciduous gymnosperms. Although differences between angiosperms and gymnosperms dominate the variance in n-alkane abundance, leaf life-span is also important, with higher n-alkane abundances in longer-lived leaves. n-Alkanol abundances covary with n-alkanes, but n-alkanoic acids have similar abundances across all plant groups. Isotopic fractionation between leaf tissue and individual alkanes (&z.epsiv;lipid) varies by as much as 10‰ among different chain lengths. Overall, &z.epsiv;lipid values are slightly lower (-4.5‰) for angiosperm than for gymnosperm (-2.5‰) n-alkanes. Angiosperms commonly express slightly higher Δleaf (photosynthetic discrimination) relative to gymnosperms under similar growth conditions. As a result, angiosperm n-alkanes are expected to be generally 3-5‰ more depleted in 13C relative to gymnosperm alkanes for the same locality. Differences in n-alkane production indicate the biomarker record will largely (but not exclusively) reflect angiosperms if both groups were present, and also that evergreen plants will likely be overrepresented compared with deciduous ones. We apply our modern lipid abundance patterns and &z.epsiv;lipid results to constrain the magnitude of the carbon isotope excursion (CIE) at the onset of the Paleocene-Eocene Thermal Maximum (55.8 Ma). When Bighorn Basin (WY) sediment n-alkanes are interpreted in context of floral changes and modern n-alkane production estimates for angiosperms and gymnosperms, the CIE is greater in magnitude (-5.6‰) by ˜1‰ compared to previous estimates that do not take into account n-alkane production.

Affiliated with

Also associated with

No associations

Rating

Production of n-alkyl lipids in living plants and implications for the geologic past does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Production of n-alkyl lipids in living plants and implications for the geologic past, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Production of n-alkyl lipids in living plants and implications for the geologic past will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1608054