Evidence for bias in C and N concentrations and δ13C composition of terrestrial and aquatic organic materials due to pre-analysis acid preparation methods

Brodie, Christopher; Leng, Melanie J.; Casford, James S.L.; Kendrick, Christopher P.; Lloyd, Jeremy M.; Zong, Yongqiang; Bird, Michael I.

doi:10.1016/j.chemgeo.2011.01.007

Cited by 219 publications

(241 citation statements)

References 54 publications

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“…One of the common approaches is to use twoor three-end-member mixing models with combined use of TOC to total nitrogen (TN) ratio (C : N) and stable carbon isotope in organic material (δ 13 C org ) (Rumolo et al, 2011;Yu et al, 2010;Liu and Kao, 2007). It is well known that there are large differences in C : N ratio and 13 C org value between exogenous and endogenous organic materials (Brodie et al, 2011;Kaushal and Binford, 1999). For example, aqueous organic matter has low C : N ratios (4-10) (Meyers, 2003) whereas vascular land plants have much higher C : N ratios (> 20) (Rumolo et al, 2011;Lamb et al, 2004;Sifeddine et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

Wang

Zhang

et al. 2015

Biogeosciences

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Abstract. Lake sediment is an important carbon reservoir. However, little is known on the dynamics and sources of sediment organic carbon in Bosten Lake. We collected 13 surface (0-2 cm) sediment samples in Bosten Lake and analyzed total organic carbon (TOC), total nitrogen (TN), stable carbon isotopic composition in TOC (δ 13 C org ), and grain size. We found a large spatial variability in TOC content (1.8-4.4 %) and δ 13 C org value (−26.77 to −23.98 ‰). Using a three-end-member mixing model with measured TOC : TN ratio and δ 13 C org , we estimated that 54-90 % of TOC was from autochthonous sources. Higher TOC content (> 3.7 %) was found in the east and central-north sections and near the mouth of the Kaidu River, which was attributable to allochthonous, autochthonous plus allochthonous, and autochthonous sources, respectively. The lowest TOC content was found in the mid-west section, which might be a result of high kinetic energy levels. Our study indicated that the spatial distribution of sediment TOC in the Bosten Lake was influenced by multiple and complex processes.

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Section: Introductionmentioning

confidence: 99%

Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

Wang

Zhang

et al. 2015

Biogeosciences

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“…For example, %C and %N can be artificially concentrated by weight in the "rinse" method due to a loss a fine colloidal materials in the discarded supernatant; and C/N, δ 13 C and δ 15 N values can be biased due to loss of fine colloidal organic in the supernatant and solubilization of OC (Brodie et al, 2011a). These values can similarly be influenced in the "capsule" and "fumigation" methods due to volatilization of OC and residual IC.…”

Section: Non-linear Unpredictable Bias To Organic Mattermentioning

confidence: 99%

“…This suggests that the measured C/N, δ 13 C and δ 15 N values of OM are not only dependent on environmental process, but also on analytical procedure, reducing the reliability of the data to the point of questioning the strength of the subsequent interpretation. Across all of the materials and pretreatment methods tested, biases in C/N were in the range of 7 -113; δ 13 C in the range of 0.2 - 7.1 ‰; and δ 15 N in the range of 0.2 - 1.5 ‰, resulting directly from bias to sample OM by acid treatment and in some instances residual IC (see Brodie et al, 2011a, b for a detailed discussion). The range and magnitude of these treatmentinduced biases indicate that the assumption that there is negligible or systematic effect from acid pre-treatment is seriously flawed.…”

Section: Non-linear Unpredictable Bias To Organic Mattermentioning

confidence: 99%

“…For example, Figures 1 and 2 show that although broccoli (Brassica oleracea) is a terrestrial C 3 plant, an aquatic or aquatic/terrestrial combination could be concluded from the data, depending upon the method and/or acid reagent (see Brodie et al, 2011a). In addition, C/N values can also vary considerably depending on whether they are calculated with %N from treated or untreated sample aliquots (see Brodie et al, 2011a, b).…”

Section: N Valuesmentioning

confidence: 99%

“…It was therefore also necessary to test whether acid pre-treatment had an effect on δ 15 N results. Hydrochloric (HCl), sulfurous (H 2 SO 3 ) and phosphoric (H 3 PO 4 ) acid, at varying strengths have been compared (e.g., Kennedy et al, 2005;Brodie et al, 2011a).…”

Section: N As Paleoenvironmental Proxiesmentioning

confidence: 99%

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Evidence for bias in C/N, δ13C and δ15N values of aquatic and terrestrial organic materials due to acid pre-treatment methods

Brodie¹

2011

PAGES news

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Influence of provenance and preservation on the carbon isotope variations of dispersed organic matter in ancient floodplain sediments

Bataille

Mastalerz

Tipple

et al. 2013

Geochem. Geophys. Geosyst.

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Carbon isotope ratios of bulk organic matter in sedimentary rocks (δ13CDOM) are a potential source of paleoenvironmental information in terrestrial stratigraphic sequences. However, insufficient understanding of the range of depositional and post‐depositional controls on δ13CDOM values makes interpretations of these data difficult. Here we evaluate the effects of organic matter (OM) provenance and preservation on δ13CDOM using records spanning the Paleocene Eocene Thermal Maximum (PETM) in the Bighorn Basin (Wyoming, USA) as a case study. We sampled sedimentary rocks spanning the PETM in two well‐studied locations—Polecat Bench (PB) and Highway 16 (HW16)—in the Bighorn Basin. Independent carbon isotope records from biomarkers and pedogenic carbonates at these sites suggest that local shifts in plant and soil δ13C values associated with the PETM CIE were broadly similar and were characterized by an abrupt ∼5‰ decrease followed by a plateau and a eventual return to pre‐PETM δ13C values. The δ13CDOM records from both sites differ significantly from these reference curves in both amplitude of change and in preserving high‐frequency isotopic fluctuations and large isotopic anomalies superimposed on the general pattern of isotopic change through the CIE. For each location, we separated organo‐mineral fractions (MOM), concentrated macerals from 20 stratigraphic levels and analyzed the carbon isotope ratio (δ13C) of each fraction. At both sites the δ13C of the fine and coarse MOM differ significantly from each other and from δ13CDOM. Concentration‐weighted mixing of these isotopically distinct OM fractions explains high resolution δ13CDOM fluctuations but does not explain the large isotopic anomalies observed at both sites. At HW16, we identified two thermally and isotopically distinct populations of macerals interpreted as being indigenous and recycled OM. At this site, one over total organic carbon (1/TOC) values correlate with δ13CDOM for pre‐PETM and PETM strata and both relationships converge toward the δ13C of recycled OM for low TOC. At PB, macerals display homogeneous thermal maturity, but the proportion of isotopically distinct vitrinite and liptinite varies between facies. Relationships between 1/TOC and δ13CDOM are also present within specific stratigraphic intervals at PB, but values do not converge on a single isotopic value across the sampled interval. These observations are consistent with variable mixing of OM fractions having different provenance—mixing of exotic recycled OM at HW16 and locally reworked OM at PB with indigenous “fresh” OM at both sites—and explain the large anomalies observed in the δ13CDOM records at both sites. Our findings raise questions about the assumption that OM in ancient sediments is indigenous and dominantly records δ13C variations of local plants.

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Evidence for bias in C and N concentrations and δ13C composition of terrestrial and aquatic organic materials due to pre-analysis acid preparation methods

Cited by 219 publications

References 54 publications

Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

Evidence for bias in C/N, δ13C and δ15N values of aquatic and terrestrial organic materials due to acid pre-treatment methods

Influence of provenance and preservation on the carbon isotope variations of dispersed organic matter in ancient floodplain sediments

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