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

Jeng, Woei‐Lih

doi:10.1016/j.marchem.2006.05.001

Cited by 180 publications

(89 citation statements)

References 41 publications

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“…The range of ACL values for the 18 streambed sediments (28.6 to 29.1) indicates higher plants were 366 the dominant sources of n-alkanes in this river system (Jeng, 2006). In contrast, sediment CPI values 367 ranged from 4.7 to 8.6, putting them at the lower end of the range observed across all source groups.…”

Section: Alkanes For Discriminating Plant Types and Sub-environments 345mentioning

confidence: 94%

Apportioning sources of organic matter in streambed sediments: An integrated molecular and compound-specific stable isotope approach

Cooper

Pedentchouk

Hiscock

et al. 2015

Science of The Total Environment

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12We present a novel application for quantitatively apportioning sources of organic matter in streambed 13 sediments via a coupled δ 2 H and δ 13 C compound-specific isotope analysis (CSIA) of leaf wax n-14 alkane biomarkers using a Bayesian mixing model. Leaf wax extracts of 13 plant species were 15 collected from across three sub-environments (aquatic, bankside and terrestrial) and four plant 16 functional types (trees, herbaceous perennials and C 3 and C 4 graminoids) from the agricultural River 17Blackwater catchment, Norfolk, UK. Nine isotopic ratio and n-alkane chain length fingerprints were 18 derived, which successfully differentiated 93% of individual plant specimens by plant functional type. ranging from -259‰ to -221‰) providing the largest contrasts. The δ 13 C values provided strong 22 distinction between C 3 and C 4 plants, and successfully discriminated between natural and cultivated 23 vegetation. n-Alkane chain length metrics complemented hydrogen and carbon isotope data by 24 2 discriminating between aquatic, bankside and terrestrial sub-environments. Neither δ 2 H nor δ 13 C 25 could uniquely identify plants based on sub-environment, emphasizing a stronger plant 26 physiological/biochemical rather than environmental control over isotopic differences. Bayesian 27 source apportionment results for 18 streambed sediments collected between September 2013 and 28March 2014, revealed considerable temporal variability in organic matter sources. Median organic 29 matter contributions ranged from 22-52% for trees, 29-50% for herbaceous perennials, 17-34% for C 3 30 graminoids and 3-7% for C 4 graminoids. The results presented here clearly demonstrate the 31 effectiveness of an integrated stable isotope and molecular approach for quantitatively apportioning 32 plant specific organic matter contributions to streambed sediments. Future research could investigate 33 whether soils under particular vegetation types are tagged with unique δ 2 H and δ 13 C signatures that 34 would allow these isotopes to be used as direct land-use specific soil erosion tracers. 35 HIGHLIGHTS 36 Organic contributions from trees, herbs and C 3 /C 4 graminoids are apportioned. 37  δ 2 H provides strong discrimination between plant functional types. 38  δ 13 C provides strong contrasts between C 3 and C 4 plants. 39  δ 2 H and δ 13 C values were not influenced by sub-environment. 40  n-Alkane chain length metrics compliment isotopic discrimination. 41

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Section: Alkanes For Discriminating Plant Types and Sub-environments 345mentioning

confidence: 94%

Apportioning sources of organic matter in streambed sediments: An integrated molecular and compound-specific stable isotope approach

Cooper

Pedentchouk

Hiscock

et al. 2015

Science of The Total Environment

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“…6a; Equation 5b; Jeng, 2006) increased with depth in the April 2014 profile, from 27.6 at the surface to 28.6 at 49 m. The increase in ACL with depth in July 2014 was smaller. The stable isotope distribution across even chain-length fatty acids in the depth-specific samples spanned a greater range than bulk δ 13 C POC values in the same samples, -34.2‰ to -27.7‰ (Fig.…”

Section: Lipid Abundances and Isotope Compositionmentioning

confidence: 88%

“…Within each sampling month, the POC-normalized compound abundances measured at the surface were greater than the abundances measured deeper in the water column. Average chain lengths (ACL) for n-alkanes Jeng, 2006) ranged from 29.6 to 30.1 and decreased slightly with depth, but did not vary significantly between the two months (Fig. 6b).…”

Section: Lipid Abundances and Isotope Compositionmentioning

confidence: 99%

Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles

Rosengard¹

2017

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Particulate organic carbon (POC) in the ocean and mobilized by rivers on land transfers ~0.1% of global primary productivity to the deep ocean sediments. This small fraction regulates the long-term carbon cycle by removing carbon dioxide from the atmosphere for centuries to millennia. This thesis investigates mechanisms of POC transfer to the deep ocean by analyzing particles collected in transit through two globally significant carbon reservoirs: the Southern Ocean and the Amazon River Basin. These endeavors test the hypothesis that organic matter composition controls the recycling and transfer efficiency of POC to the deep ocean, and illustrate new applications for ramped pyrolysis/oxidation (RPO), a growing method of POC characterization by thermal stability. By coupling RPO to stable and radiocarbon isotope analyses of riverine POC, I quantify three thermally distinct soil organic carbon pools mobilized by the Amazon River, and evaluate the degradability and fate of these different pools during transport to the coastal Atlantic Ocean. More directly, RPO analyses of marine samples suggest that POC transfer in the water column is in fact selective. Observations of consistent biomolecular changes that accompany transport of phytoplankton-derived organic matter to depth across the Southern Ocean support the argument for preferential degradation of specific POC pools in the water column. Combining discussions of POC recycling and transfer across both marine and terrestrial systems offer new perspectives of thermal stability as a proxy for diagenetic stability and POC degradation state. The challenges of interpreting RPO data in these two environments set the stage for applying the technique to more controlled experiments that trace POC from source to long-term sink.

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“…Higher plants retain water in their leaves by biosynthesis of epicuticular wax with long chain n-alkanes, while algae synthesize short n-alkanes, so CPI values >5 are attributed to a terrigenous source, while those close to unity can be associated with petroleum contamination [38].…”

Section: Discussion N-alkane Distributionmentioning

confidence: 99%

Effect of the Little Ice Age on Climate and Vegetation Recorded by n-Alkanes and Glycerol Dialkyl Glycerol Tetraether Proxies

Machado¹,

Froehnerb²

2015

J Earth Sci Clim Change

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Keywords: Climatic changes; Little ice age; n-Alkane distributions; GDGT proxies IntroductionThe period which was subjected to much colder winters followed by warmer periods is known as the little ice age (LIA). It documented as being between about 1300 and 1870 (Mann, 2002). However, climate change could vary geographically [1]. The period is divided into two phases; the first was around 1300 until the late 1400s and the second warmer period was in in the 1500s [2]. The period between 1600 and 1850 marks its height and was characterized by changes in the hydrological cycle and perturbation of the ecosystem [2-4].Even although there much evidence for the LIA, the causes and mechanism are still under debate. The only certainty is that it was a global event. Most studies have focused on the northern hemisphere [3][4][5], and there are few studies demonstrating the occurrence of the event in the southern hemisphere. For instance, in South America [6,7], advance in glaciers in the Andes was demonstrated [8], as well as aridity in the lowlands of Argentina [9] and Venezuela [8], and there is evidence from mountain glaciers suggesting increasing glaciation in Patagonia [10]. In Brazil, some studies have demonstrated change in vegetation composition during the LIA and sea level regression in northeastern and southeastern Brazil [11][12][13].At present, paleoclimate can be reconstructed due the widespread occurrence of biomarkers multi-proxy data derived from them. The spatial and temporal character of such putative climate epochs revived the discussion and understanding of and mechanism for the LIA, as well as of the implications for climate change in the future.Typically, n-alkanes are derived from different sources (algae, photosynthetic bacteria and higher plants [14]. Different distribution patterns of n-alkanes in sediments provides information about different climatic environments and hence is widely used to understand the evolution of vegetation and reconstruct environmental changes [14,15]. The magnitude of the anthropogenic impact on the climate and the environment was recently measured from biomarker distributions [4,14]. Yet, some biomarkers can be more specific in their information than n-alkanes. For example, increasing attention has been driven to glycerol dialkyl glycerol tetraether (GDGT) compounds, polar basic constituents of the cell membrane and comprising a polar head group bonded to a non-polar hydrocarbon [16]. The structures of GDGTs are temperature dependent. When temperature increases, cyclopentane moieties are formed within the isoprenoid chain [17]. With more cyclopentane rings, the membrane is kept in a liquid crystalline state and, as a consequence, proton permeation is reduced.According to Weijers et al. [18] there are some environmental controls on the distributions of GDGTs, so two indices were proposed for quantifying the degree of methylation (MBT) and cyclization (CBT), both being effective in palaeoenvironmental studies to reconstruct mean annual air temperature (MAAT). Since branche...

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

Cited by 180 publications

References 41 publications

Apportioning sources of organic matter in streambed sediments: An integrated molecular and compound-specific stable isotope approach

Apportioning sources of organic matter in streambed sediments: An integrated molecular and compound-specific stable isotope approach

Novel analytical strategies for tracing the organic carbon cycle in marine and riverine particles

Effect of the Little Ice Age on Climate and Vegetation Recorded by n-Alkanes and Glycerol Dialkyl Glycerol Tetraether Proxies

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