Temporal deconvolution of vascular plant-derived fatty acids exported from terrestrial watersheds

Vonk, Jorien E.; Drenzek, Nicholas J.; Hughen, Konrad A; Stanley, Rachel H. R.; McIntyre, Cameron; Montluçon, Daniel B.; Giosan, Liviu; Southon, John; Santos, Guaciara M.; Druffel, Ellen R. M.; Andersson, August; Sköld, Martin; Eglinton, Timothy I.

doi:10.1016/j.gca.2018.09.034

Cited by 26 publications

(31 citation statements)

References 104 publications

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“…This offset between both biomarker 14 C ages and catchment-weighted soil 14 C ages on one hand and τ soil on the other hand likely reflects the fundamental principles governing organic matter degradation and aging. Natural organic matter is compositionally heterogenous, with age heterogeneity evident even within individual compound populations ( 20 , 35 ). Complex interplay between environmental properties and chemical composition results in widely variable OC degradation rates ( 36 ).…”

Section: Resultsmentioning

confidence: 99%

“…Recently synthesized biospheric carbon then transmits this bomb 14 C signal through river basins, inducing time-variable deviations from natural 14 C levels. We have examined this potential influence on observed signals for selected river systems in two different ways: 1) through comparison of data from samples from the same river system but collected at different times over the last few decades; and 2) through analysis of rapidly accumulating and well-dated fluvially influenced sedimentary sequences with well-defined chronologies that span a time interval encompassing the bomb spike ( 20 , 35 ). Although the influence of the bomb 14 C spike clearly manifests itself in plant-wax fatty acids, the induced variability is small relative to the overall 14 C variability observed within the global dataset presented in this study.…”

Section: Methodsmentioning

confidence: 99%

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Climate control on terrestrial biospheric carbon turnover

Eglinton

Galy

Hemingway

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Terrestrial vegetation and soils hold three times more carbon than the atmosphere. Much debate concerns how anthropogenic activity will perturb these surface reservoirs, potentially exacerbating ongoing changes to the climate system. Uncertainties specifically persist in extrapolating point-source observations to ecosystem-scale budgets and fluxes, which require consideration of vertical and lateral processes on multiple temporal and spatial scales. To explore controls on organic carbon (OC) turnover at the river basin scale, we present radiocarbon (14C) ages on two groups of molecular tracers of plant-derived carbon—leaf-wax lipids and lignin phenols—from a globally distributed suite of rivers. We find significant negative relationships between the 14C age of these biomarkers and mean annual temperature and precipitation. Moreover, riverine biospheric-carbon ages scale proportionally with basin-wide soil carbon turnover times and soil 14C ages, implicating OC cycling within soils as a primary control on exported biomarker ages and revealing a broad distribution of soil OC reactivities. The ubiquitous occurrence of a long-lived soil OC pool suggests soil OC is globally vulnerable to perturbations by future temperature and precipitation increase. Scaling of riverine biospheric-carbon ages with soil OC turnover shows the former can constrain the sensitivity of carbon dynamics to environmental controls on broad spatial scales. Extracting this information from fluvially dominated sedimentary sequences may inform past variations in soil OC turnover in response to anthropogenic and/or climate perturbations. In turn, monitoring riverine OC composition may help detect future climate-change–induced perturbations of soil OC turnover and stocks.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Climate control on terrestrial biospheric carbon turnover

Eglinton

Galy

Hemingway

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…These biomarkers, and associated techniques, have identified that land-based organic material is sometimes a major contributor to marine particulate organic matter flux. While many of these and other tracer studies confirm the terrigenous origin of particulate organic matter and sediments, they do not identify the specific catchment sources unless a single major river inflow is in proximity (Vonk et al, 2019).…”

Section: Introductionmentioning

confidence: 85%

Novel Application of a Compound-Specific Stable Isotope (CSSI) Tracking Technique Demonstrates Connectivity Between Terrestrial and Deep-Sea Ecosystems via Submarine Canyons

et al. 2020

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Studies have shown the importance of submarine canyons as conduits of land-derived organic carbon beyond the coastal shelf into the deep-sea where a single obvious river source can be identified. When there is more than one river source, identifying which rivers contribute to canyon sediment organic matter is technically challenging. Here, we compare two contrasting submarine canyons: the Hokitika Canyon, a long, narrow, and gently sloping canyon on the west coast of New Zealand; and the Kaikōura Canyon, a high productivity, short, steep canyon close to shore on the east coast of New Zealand. Both canyons have multiple potential river sources, so we applied a compound specific stable isotope (CSSI) tracking technique to identify and apportion the contribution from each river at locations along the length of each canyon axis. We found that land-derived organic matter contributed between 74 and 100% of the total organic matter in the sediment of the Hokitika Canyon as far as 200 km from shore and to depths of 2000 m. However, less than 50% of the land-derived organic carbon came from the largest river closest to the canyon head. We hypothesize that longshore drift transported much of the sediment from that river past the Hokitika Canyon, while river inflows farther up-current supplied the bulk of the land-derived organic carbon. In contrast, land-derived organic matter contributed less than 50% of the total organic matter in Kaikōura Canyon sediments with land-derived organic sediment contribution decreasing steeply to less than 15% at about 24 km from shore in 1500 m water depth. Most of the land-derived organic matter (ca. 80%) came from the river with the largest suspended sediment yield, despite another (smaller) river discharging closer to the canyon head. We hypothesize that this difference in carbon source is partly due to

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“…The IIIa/IIa ratio (Xiao et al, 2016;Martin et al, 2019) is 1.6 ± 0.4 for UD-4, 1.5 ± 0.2 for MD-2 and 1.4 ± 0.3 for MD-1, which also points toward a lacustrine in situ production (the reported threshold is > 0.9 for in situ aquatic production, in one soil of the Mackenzie region it is 1.2, Peterse et al, 2014). The Mackenzie River transports large quantities of soil-derived organic matter (Vonk et al, 2019), and is therefore a potential source of soil-derived brGDGTs, especially to the no-closure lakes. However, the distribution of brGDGTs in Mackenzie River SPM differs from that in lakes with IIa (IIa + IIa') and IIIa (IIIa = 15% and IIIa' = 19%) as main brGDGTs (34% each, Peterse et al, 2014) and IIIa/IIa equal to 1.0 ± 0.1 (n = 6; Peterse et al, 2014).…”

Section: Provenance Of Brgdgt Lipidsmentioning

confidence: 81%

Microbial lipid signatures in Arctic deltaic sediments - insights into methane cycling and climate variability

Lattaud

Jonge

Pearson

et al. 2020

Preprint

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Glycerol Dialkyl Glycerol Tetraethers (GDGTs) are ubiquitous biomolecules whose structural diversity or isotopic composition is increasingly used to reconstruct environmental changes such as air temperatures or pCO2. Isoprenoid GDGTs, in particular GDGT-0, are biosynthesized by a large range of Archaea. To assess the potential of GDGT-0 as a tracer of past methane cycle variations, three sediment cores from the Mackenzie River Delta have been studied for iGDGT and diploptene distribution and stable carbon signature. The absence of crenarchaeol, high GDGT-0 vs crenarchaeol ratio, and 13 C-enriched carbon signature of GDGT-0 indicate production by acetoclastic methanogens as well as heterotrophic Archaea. The oxidation of methane seems to be dominated by bacteria as indicated by the high abundance of 13 C-depleted diploptene. Branched GDGTs, thought to be produced by heterotrophic bacteria, are dominated by hexa-and penta-methylated 5-and 6-methyl compounds. The presence of 5,6-methyl isomer IIIa'' points towards in situ production of brGDGTs, with only a minor input from soil branched GDGT brought by the Mackenzie River. Carbon isotopic compositions of brGDGTs are in agreement with heterotrophic producers, likely living during summer. The reconstructed temperatures using a global lake calibration reflect recorded summer air temperature (± 2.14 °C) during the last 60 years, and further highlight the absence of warming in summer in this region during the last 200 years. Oxygen availability and connection time to the Mackenzie River also seem to control the distribution of branched GDGT with an increase in 6-methyl and 5,6-methyl isomers with increased period of anoxia.

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Temporal deconvolution of vascular plant-derived fatty acids exported from terrestrial watersheds

Cited by 26 publications

References 104 publications

Climate control on terrestrial biospheric carbon turnover

Climate control on terrestrial biospheric carbon turnover

Novel Application of a Compound-Specific Stable Isotope (CSSI) Tracking Technique Demonstrates Connectivity Between Terrestrial and Deep-Sea Ecosystems via Submarine Canyons

Microbial lipid signatures in Arctic deltaic sediments - insights into methane cycling and climate variability

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