Separation of total nitrogen from sediments into organic and inorganic forms for isotopic analysis

Li, Zhiyang; Jia, Guodong

doi:10.1016/j.orggeochem.2011.01.004

Cited by 17 publications

(15 citation statements)

References 18 publications

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“…While losses of OM by HF demineralization are often negligible for samples that have undergone some diagenetic alteration (e.g., shales), HF demineralization of soils and immature sediments can cause OM losses as high as 50–90% of total organic C. ,− To overcome the problem of OM losses during HF demineralization, Gélinas et al proposed a procedure to recover OM solubilized in HF involving pH adjustments, precipitation of dissolved metals and chromatographic desalting, which allowed them to increase recoveries of organic C (C org ) from 32 to 95% to 80–95%. Recently, Li and Jia proposed solid-phase extraction (SPE) using Bond Elut PPL sorbent (Agilent Technologies Inc., USA) to recover solubilized organic matter from HF in an attempt to separate organic from inorganic N in a marine sediment sample and reported a C org recovery of 98%. Besides Bond Elut PPL, Oasis HLB sorbent (Waters Corp., USA) has been reported to yield good recoveries of soluble organic compounds. , …”

Section: Introductionmentioning

confidence: 99%

Optimized Demineralization Technique for the Measurement of Stable Isotope Ratios of Nonexchangeable H in Soil Organic Matter

Ruppenthal

Oelmann

Wilcke

2012

Environ. Sci. Technol.

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To make use of the isotope ratio of nonexchangeable hydrogen (δ(2)H(n (nonexchangeable))) of bulk soil organic matter (SOM), the mineral matrix (containing structural water of clay minerals) must be separated from SOM and samples need to be analyzed after H isotope equilibration. We present a novel technique for demineralization of soil samples with HF and dilute HCl and recovery of the SOM fraction solubilized in the HF demineralization solution via solid-phase extraction. Compared with existing techniques, organic C (C(org)) and organic N (N(org)) recovery of demineralized SOM concentrates was significantly increased (C(org) recovery using existing techniques vs new demineralization method: 58% vs 78%; N(org) recovery: 60% vs 78%). Chemicals used for the demineralization treatment did not affect δ(2)H(n) values as revealed by spiking with deuterated water. The new demineralization method minimized organic matter losses and thus artificial H isotope fractionation, opening up the opportunity to use δ(2)H(n) analyses of SOM as a new tool in paleoclimatology or geospatial forensics.

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Section: Introductionmentioning

confidence: 99%

Optimized Demineralization Technique for the Measurement of Stable Isotope Ratios of Nonexchangeable H in Soil Organic Matter

Ruppenthal

Oelmann

Wilcke

2012

Environ. Sci. Technol.

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“…The estimated recovery of SNFs obtained via the sequential extraction method was 95–104%, and their N concentrations varied with the types and concentrations of extraction agents (Table 1). It is interesting that MA‐N accounted for the highest proportion among moderately stable N (Table 1); this is because of the ability of mixed acid to destroy part of the clay minerals and release part of the fixed ammonium (Cheng et al, 1975; Z. Y. Li & Jia, 2011; Sahrawat, 1995). Stable N had the highest contributions among all SNFs (Table 1), suggesting that it is difficult to extract these N fractions with agents such as mixed acid and HCl at 25°C because of the complex combination of soil organic N and clay minerals.…”

Section: Discussionmentioning

confidence: 99%

“…H 2 O, 1 M HCl and 6 M HCl were selected because they are commonly used in the extraction of soil inorganic N and organic N fractions (Bremner, 1965; Jones & Willett, 2006), and CaCl 2 is a common extraction reagent for other soil elements (Alan & Kara, 2019; Blombäck et al, 2021). Mixed acids were introduced because studies have revealed that they destroy part of soil clay minerals (Cheng, Shufeldt, & Stevenson, 1975; Z. Y. Li & Jia, 2011; Sahrawat, 1995). The RES‐N was measured by the same method as TN, through concentrated H 2 SO 4 digestion, which was similar to the residue of other soil elements by sequential extraction method (Alan & Kara, 2019).…”

Section: Methodsmentioning

confidence: 99%

Interaction effects of environmental factors on soil nitrogen fractions based on a novel sequential extraction method

Wang

Zhang

Zhong

et al. 2021

European J Soil Science

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Soil nitrogen (N) is controlled by several environmental factors. However, it is unclear how these factors and their interactions affect soil N fractions (SNFs) because of the lack of systematic N extraction methods. The Harbin–Dali belt, a transect more than 3,300 km long across China covering various climates, topographies, soil parent materials and vegetation types, was taken as the study area, and the interactive effects on SNFs in largely undisturbed woodlands and grasslands were explored using three SNFs: labile N, moderately stable N and stable N. The soil N fractions were obtained through a novel sequential extraction method that used distilled H2O, 0.5 M CaCl2, 1 M HCl, 6 M HCl, mixed acid (1 M HCl and 5 M HF; MA), concentrated HCl (cHCl) and concentrated H2SO4 as extractive agents to successively separate H2O‐, CaCl2‐, 1 M HCl‐, 6 M HCl‐, MA‐, cHCl‐ and RES‐N fractions. The results showed that increasing mean annual temperature (MAT) directly decreased the concentrations of H2O‐, CaCl2‐ and 1 M HCl‐N, suggesting that warming may reduce available N. The interactions between MAT, parent material, aspect and aridity index also contributed to the three SNFs. Vegetation and its interactions with parent material primarily controlled 6 M HCl‐, cHCl‐ and RES‐N, and climate and topography had indirect effects during these processes. Particularly, more cHCl‐ and RES‐N were accumulated in areas with warm humid climates and rich vegetation species than in other environments. Moreover, soil labile N (H2O‐, CaCl2‐ and 1 M HCl‐N) and cHCl‐N exhibited potential as sensitive indicators for reflecting the changes in MAT and vegetation, respectively. Therefore, the various interactions between climate and other environmental factors controlled the changes in most SNFs. This novel sequential extraction method thus offers a reliable analytical approach to measuring SNFs. Highlights Soil nitrogen fractions (SNFs) were fractionated via a novel sequential extraction method. Increasing MAT decreased the H2O‐, CaCl2‐ and 1 M HCl‐N concentrations. Interactions of climate, parent material and vegetation affected 6 M HCl‐, MA‐, cHCl‐ and RES‐N. H2O‐, CaCl2‐, 1 M HCl‐ and cHCl‐N are sensitive SNFs that reflect environmental changes.

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“…Nitrogen isotopic analyses on the kerogen samples were conducted using a modified elemental analysis-isotope ratio mass spectrometry (EA-IRMS) system (CEEA1112 C/N/S Analyser interfaced with a DELTA plus XL mass spectrometer) at Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (Li & Jia 2011). The measurement results were corrected for the procedural N 2 blank and normalized using three-point calibration.…”

Section: Sampling and Methodsmentioning

confidence: 99%

Marine C, S and N biogeochemical processes in the redox-stratified early Cambrian Yangtze ocean

Cai

Xiang

Yuan

et al. 2015

JGS

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The temporal change of redox conditions of the Yangtze ocean has been revealed by investigating the Ediacaran-Cambrian transition section at Zhalagou, South China. During the earliest Cambrian, cherts and shales were deposited under an anoxic and ferruginous bottom water with significantly increasing total organic carbon and P contents, and negative shift in kerogen δ 13 C values in the lowest part of the section. Euxinic bottom water conditions occurred during the earliest Cambrian Stage 2, with the surface water dominated by N 2 utilization by cyanobacteria or sulphur bacteria leading to negative kerogen δ 15 N values. During Stage 3, dissolved oxygen and sulphate concentrations were significantly increased, and thus the oxidized surface water and the redox transition zone overlying a euxinic bottom water may have been expanded, resulting in an increase in kerogen δ 15 N increasing to 2-4‰, a decrease in pyrite δ 34 S decreasing to as low as -24.6‰ and differences in δ 34 S values between kerogen and pyrite as high as 37‰. This period coincided with the abrupt appearance of large-body metazoans. Thus, the expanding oxic surface water may have reinforced the evolution of animals or vice versa. Interestingly, kerogen δ 34 S values show negative relationships to FePy/FeHR ratios and pyrite sulphur contents, indicating that they can be used to reflect redox conditions, with the lightest values being obtained from euxinic environments.

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Separation of total nitrogen from sediments into organic and inorganic forms for isotopic analysis

Cited by 17 publications

References 18 publications

Optimized Demineralization Technique for the Measurement of Stable Isotope Ratios of Nonexchangeable H in Soil Organic Matter

Optimized Demineralization Technique for the Measurement of Stable Isotope Ratios of Nonexchangeable H in Soil Organic Matter

Interaction effects of environmental factors on soil nitrogen fractions based on a novel sequential extraction method

Marine C, S and N biogeochemical processes in the redox-stratified early Cambrian Yangtze ocean

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