scholarly journals Dating Charred Soil Organic Matter: Comparison of Radiocarbon Ages from Macrocharcoals and Chemically Separated Charcoal Carbon

Radiocarbon ◽  
2009 ◽  
Vol 51 (2) ◽  
pp. 437-443 ◽  
Author(s):  
Eileen Eckmeier ◽  
Klaas Van der Borg ◽  
Ursula Tegtmeier ◽  
Michael W I Schmidt ◽  
Renate Gerlach
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Age Differences ◽  
Radiocarbon Dating ◽  
High Energy ◽  
Soil Samples ◽  
Data Sets ◽  
Soil Material ◽  
Photo Oxidation ◽  
Environmental Processes

Radiocarbon dating of charcoal in soils is commonly used to reconstruct past environmental processes. Also microcharcoal that is chemically isolated from soil organic matter by high-energy UV photo-oxidation can be dated with 14C accelerator mass spectrometry (AMS). We compared the 14C AMS ages of 13 pairs of hand-picked macrocharcoals and microcharcoal samples separated via the UV oxidation method; both charcoal fractions were taken from the same soil samples (prehistoric pit fillings). We found that in most cases, the microcharcoal fraction yielded older ages than the single macrocharcoal pieces, and that the differences between the ages are not systematic. A reason for these age differences might be that the microcharcoal fraction consists of more stable components than macrocharcoals and thus yields older ages. Dating of microcharcoal would give a mean age of charred organic matter in soil material and the ages of the more stable compounds. Thus, 14C data obtained from the microcharcoal fraction in soils is not comparable to macrocharcoal ages and should not be used to complement existing macrocharcoal data sets.

scholarly journals Radiocarbon Dating of Soil Organic Matter Fractions in Andosols in Northern Ecuador

Radiocarbon ◽  
2006 ◽  
Vol 48 (3) ◽  
pp. 337-353 ◽  
Author(s):  
Femke H Tonneijck ◽  
Johannes van der Plicht ◽  
Boris Jansen ◽  
Jacobus M Verstraten ◽  
Henry Hooghiemstra
Keyword(s):  
Organic Matter ◽  
Humic Acid ◽  
Soil Organic Matter ◽  
Forest Floor ◽  
Radiocarbon Dating ◽  
Mineral Soil ◽  
Soil Samples ◽  
Acid Extraction ◽  
Independent Evidence ◽  
Organic Horizons

Volcanic ash soils (Andosols) may offer great opportunities for paleoecological studies, as suggested by their characteristic accumulation of organic matter (OM). However, understanding of the chronostratigraphy of soil organic matter (SOM) is required. Therefore, radiocarbon dating of SOM is necessary, but unfortunately not straightforward. Dating of fractions of SOM obtained by alkali-acid extraction is promising, but which fraction (humic acid or humin) renders the most accurate 14C dates is still subject to debate. To determine which fraction should be used for 14C dating of Andosols and to evaluate if the chronostratigraphy of SOM is suitable for paleoecological research, we measured 14C ages of both fractions and related calibrated ages to soil depth for Andosols in northern Ecuador. We compared the time frames covered by the Andosols with those of peat sequences nearby to provide independent evidence. Humic acid (HA) was significantly older than humin, except for the mineral soil samples just beneath a forest floor (organic horizons), where the opposite was true. In peat sections, 14C ages of HA and humin were equally accurate. In the soils, calibrated ages increased significantly with increasing depth. Age inversions and homogenization were not observed at the applied sampling distances. We conclude that in Andosols lacking a thick organic horizon, dating of HA renders the most accurate results, since humin was contaminated by roots. On the other hand, in mineral soil samples just beneath a forest floor, humin ages were more accurate because HA was then contaminated by younger HA illuviated from the organic horizons. Overall, the chronostratigraphy of SOM in the studied Andosols appears to be suitable for paleoecological research.

Radiocarbon Variation in Charcoal/Wood and Soil Fractions from a Loessic Setting in Central Alaska

Radiocarbon ◽  
2016 ◽  
Vol 59 (2) ◽  
pp. 449-464 ◽  
Author(s):  
Joshua D Reuther ◽  
Alexander Cherkinsky ◽  
Sam Coffman
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Residence Time ◽  
Age Differences ◽  
Soil Formation ◽  
Soil Samples ◽  
Small Particles ◽  
Vegetation Development ◽  
Lucky Strike ◽  
Soil Residue

AbstractThe Healy’s Lucky Strike site in central Alaska has an exceptional Holocene loess-paleosol sequence that has afforded us the ability to look at variation in 14C dating of soil organic matter (SOM) fractions in a high-latitude loess setting. Our work has focused on comparing the radiocarbon ages of charcoal and wood to base-soluble humic acids (HA) and base-insoluble soil residue (SR) fractions from bulk soil samples. Charcoal/wood ages were younger than HA ages reflecting the later stages of vegetation development at the surface of the soils prior to being covered by loess accumulation; the HA ages generally reflect the overall timing of soil formation and mean residence time of SOM. Soil residue ages are older than charcoal/wood and HA ages. SOM ages at this location become increasingly older than charcoal/wood ages with depth, reaching 750 to 8070 yr in difference and associated with weakly developed soils at the lowest depths. We suggest the drastic SOM age differences at this site result from the differential incorporation of small particles of coal throughout the sedimentary matrices introduced older contaminants to SR fractions.

Virtual fractionation of charcoal from soil organic matter using solid state 13C NMR spectral editing

Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 665 ◽  
Author(s):  
R. J. Smernik ◽  
J. O. Skjemstad ◽  
J. M. Oades
Keyword(s):  
Organic Matter ◽  
Solid State ◽  
Soil Organic Matter ◽  
13C Nmr ◽  
High Energy ◽  
Proton Spin ◽  
Inversion Recovery ◽  
Spectral Editing ◽  
Photo Oxidation ◽  
Solid State 13C Nmr

The solid state 13C NMR spectral editing technique proton spin relaxation editing (PSRE), which generates subspectra of components that have different proton relaxation rates and are spatially separated by at least 30–100 nm, was applied to hydrofluoric acid treated <53 m soil fractions from 8 Australian surface soils. Most of the aromatic signal was partitioned into the rapidly relaxing subspectrum, especially for the soils known to have high charcoal contents. However, the presence of other rapidly relaxing soil organic matter (SOM) components prevented a clean separation of charcoal from non-charcoal components. PSRE analysis was repeated after the samples had been treated with high energy ultraviolet photo-oxidation, which brings about the mineralisation of most SOM other than char. Excellent separation of the charcoal fraction by PSRE was achieved after photo-oxidation for 5 of the samples with the highest charcoal content. The rapidly relaxing subspectra for these samples also suggested that the charcoal present in soil contains significant carbonyl functionality, possibly as a result of in situ weathering. A new PSRE methodology is described, designed to best suit SOM samples. Data from inversion-recovery experiments were fitted to a model consisting of 2 components with different T1H relaxation rate constants, thus providing an objective best fit to the inversion-recovery data and avoiding the subjective judgements required in other PSRE methodologies.

scholarly journals Hamburg University Radiocarbon Dates I

Radiocarbon ◽  
1976 ◽  
Vol 18 (3) ◽  
pp. 268-289 ◽  
Author(s):  
H W Scharpenseel ◽  
F Pietig ◽  
H Schiffmann
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Radiocarbon Dating ◽  
Soil Samples ◽  
Radiocarbon Dates ◽  
Soil Organic Matter Fractions ◽  
Quartz Vial ◽  
Organic Matter Fractions

Radiocarbon measurements are carried out mainly on soil samples and soil organic matter fractions. Benzene samples are prepared as described earlier (Scharpenseel and Pietig, 1969; 1970). Radioactivity is measured in a single quartz vial, using a Packard Tri Carb Model 3075 as well as a Berthold Betascint BF 5000. Most equipment has been transferred from Bonn University Radiocarbon Dating Lab to Hamburg, where operation of former Bonn Radiocarbon Lab will be continued.

Post-thinning soil organic matter evolution and soil CO2 effluxes in temperate radiata pine plantations: impacts of moderate thinning regimes on the forest C cycle

2012 ◽  
Vol 42 (11) ◽  
pp. 1953-1964 ◽  
Author(s):  
Irene Fernandez ◽  
Juan Gabriel Álvarez-González ◽  
Beatríz Carrasco ◽  
Ana Daría Ruíz-González ◽  
Ana Cabaneiro
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Radiata Pine ◽  
Soil Samples ◽  
Mitigation Strategies ◽  
Change Scenario ◽  
Soil C ◽  
C Storage ◽  
C Cycle ◽  
C And N

Forest ecosystems can act as C sinks, thus absorbing a high percentage of atmospheric CO2. Appropriate silvicultural regimes can therefore be applied as useful tools in climate change mitigation strategies. The present study analyzed the temporal changes in the effects of thinning on soil organic matter (SOM) dynamics and on soil CO2 emissions in radiata pine ( Pinus radiata D. Don) forests. Soil C effluxes were monitored over a period of 2 years in thinned and unthinned plots. In addition, soil samples from the plots were analyzed by solid-state 13C-NMR to determine the post-thinning SOM composition and fresh soil samples were incubated under laboratory conditions to determine their biodegradability. The results indicate that the potential soil C mineralization largely depends on the proportion of alkyl-C and N-alkyl-C functional groups in the SOM and on the microbial accessibility of the recalcitrant organic pool. Soil CO2 effluxes varied widely between seasons and increased exponentially with soil heating. Thinning led to decreased soil respiration and attenuation of the seasonal fluctuations. These effects were observed for up to 20 months after thinning, although they disappeared thereafter. Thus, moderate thinning caused enduring changes to the SOM composition and appeared to have temporary effects on the C storage capacity of forest soils, which is a critical aspect under the current climatic change scenario.

Estimation of soil organic matter using proximal and satellite sensors after a wildfire in Mediterranean Croatia

2021 ◽  
Author(s):  
Iva Hrelja ◽  
Ivana Šestak ◽  
Igor Bogunović
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Spectral Data ◽  
Near Infrared ◽  
Mean Squared Error ◽  
Nir Spectroscopy ◽  
Soil Samples ◽  
Least Squares Regression ◽  
Macro Scale ◽  
Sentinel 2

&lt;p&gt;Spectral data obtained from optical spaceborne sensors are being recognized as a valuable source of data that show promising results in assessing soil properties on medium and macro scale. Combining this technique with laboratory Visible-Near Infrared (VIS-NIR) spectroscopy methods can be an effective approach to perform robust research on plot scale to determine wildfire impact on soil organic matter (SOM) immediately after the fire. Therefore, the objective of this study was to assess the ability of Sentinel-2 superspectral data in estimating post-fire SOM content and comparison with the results acquired with laboratory VIS-NIR spectroscopy.&lt;/p&gt;&lt;p&gt;The study is performed in Mediterranean Croatia (44&amp;#176; 05&amp;#8217; N; 15&amp;#176; 22&amp;#8217; E; 72 m a.s.l.), on approximately 15 ha of fire affected mixed &lt;em&gt;Quercus ssp.&lt;/em&gt; and &lt;em&gt;Juniperus ssp.&lt;/em&gt; forest on Cambisols. A total of 80 soil samples (0-5 cm depth) were collected and geolocated on August 22&lt;sup&gt;nd&lt;/sup&gt; 2019, two days after a medium to high severity wildfire. The samples were taken to the laboratory where soil organic carbon (SOC) content was determined via dry combustion method with a CHNS analyzer. SOM was subsequently calculated by using a conversion factor of 1.724. Laboratory soil spectral measurements were carried out using a portable spectroradiometer (350-1050 nm) on all collected soil samples. Two Sentinel-2 images were downloaded from ESAs Scientific Open Access Hub according to the closest dates of field sampling, namely August 31&lt;sup&gt;st&lt;/sup&gt; and September 5&lt;sup&gt;th &lt;/sup&gt;2019, each containing eight VIS-NIR and two SWIR (Short-Wave Infrared) bands which were extracted from bare soil pixels using SNAP software. Partial least squares regression (PLSR) model based on the pre-processed spectral data was used for SOM estimation on both datasets. Spectral reflectance data were used as predictors and SOM content was used as a response variable. The accuracy of the models was determined via Root Mean Squared Error of Prediction (RMSE&lt;sub&gt;p&lt;/sub&gt;) and Ratio of Performance to Deviation (RPD) after full cross-validation of the calibration datasets.&lt;/p&gt;&lt;p&gt;The average post-fire SOM content was 9.63%, ranging from 5.46% minimum to 23.89% maximum. Models obtained from both datasets showed low RMSE&lt;sub&gt;p &lt;/sub&gt;(Spectroscopy dataset RMSE&lt;sub&gt;p&lt;/sub&gt; = 1.91; Sentinel-2 dataset RMSE&lt;sub&gt;p&lt;/sub&gt; = 0.99). RPD values indicated very good predictions for both datasets (Spectrospcopy dataset RPD = 2.72; Sentinel-2 dataset RPD = 2.22). Laboratory spectroscopy method with higher spectral resolution provided more accurate results. Nonetheless, spaceborne method also showed promising results in the analysis and monitoring of SOM in post-burn period.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Keywords:&lt;/strong&gt; remote sensing, soil spectroscopy, wildfires, soil organic matter&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgment: &lt;/strong&gt;This work was supported by the Croatian Science Foundation through the project &quot;Soil erosion and degradation in Croatia&quot; (UIP-2017-05-7834) (SEDCRO). Aleksandra Per&amp;#269;in is acknowledged for her cooperation during the laboratory work.&lt;/p&gt;

Metal contamination of urban soils in Cork, Ireland

2021 ◽  
Author(s):  
Hannah Binner ◽  
Timothy Sullivan ◽  
Maria E. Mc Namara
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Metal Contamination ◽  
Urban Soils ◽  
Soil Samples ◽  
Ex Situ ◽  
City Centre ◽  
Metal Concentrations ◽  
Ph Values ◽  
Background Levels

&lt;p&gt;Soil contamination is widespread across Europe. In particular, contamination of urban soils by metals is poorly characterised. This is a major environmental concern, especially given that urban recreational amenities may be located on former industrial sites and/or may possess ex situ soils derived from industrial areas. We surveyed soils from nine urban recreational sites (15 samples per site) in Cork city in order to assess the degree of metal contamination. The results show that Pb concentrations exceed national background levels in all soil samples from all sites by a mean of 600 % and at least 140 %. Mn, Fe and Zn are enriched above background levels in all soil samples from three (Mn and Fe) to five (Zn) of the sites and, at the remaining sites, show 7 &amp;#8211; 14 localised hotspots. Similar hotspots characterise Cu, Rb and Sr, which each exceed background levels at eight or more sampling locations at four sites. Co, Ni, As and Sn concentrations exceed background levels in at least three hotspots at each of three to six sites. Overall, metal concentrations are highest in the sites closest to the city centre, reflecting diverse sources that potentially include traffic and current and historical domestic coal burning and industry. At each urban site, the element grouping Zn and Pb recurs in 50 to 80 % of locations and enrichment in the element grouping Mn, Fe, Cu, Zn and Pb recurs in approx. 50 % of locations; Ni and As recur in approx. 10 % of the locations. At three sites, elevated concentrations of Mn, Fe, Cu, Zn and Pb are associated with high LOI (Loss-on-ignition) values &amp;#8211; a proxy for the amount of soil organic matter present &amp;#8211; and near-neutral pH values. Conversely, low LOI and acidic pH values are associated with lower concentrations of these elements. This indicates that soil metal concentrations are influenced by the amount of organic matter present and by pH. &amp;#160;Future analyses and experiments will further investigate links between soil organic matter and metal concentrations.&lt;/p&gt;

scholarly journals Potential relevance of Mortierella alpina as a source of ice nucleating particles in soil

2018 ◽  
Author(s):  
Franz Conen ◽  
Mikhail V. Yakutin
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Fungus ◽  
Soil Samples ◽  
Mortierella Alpina ◽  
Soil Particles ◽  
The Tropics

Abstract. Soil organic matter carries ice nucleating particles (INP) of which the origin is hard to define and that are active at slight supercooling. The discovery and characterisation of INP produced by the widespread soil fungus Mortierella alpina permits a more targeted investigation of the likely origin of INP in soils. We searched for INP with characteristics similar to those reported for M. alpina (INPM-like) in 20 soil samples from four areas in the northern midlatitudes and one area in the tropics. In the 15 samples where we could detect INPM-like, they constituted between 1 and 94 % (median 11 %) of all INP active at −10 °C or warmer associated with soil particles

Compound-specific δ2H using analytical pyrolysis (Py-CSIA) for assessing source and processes of soil organic matter driven by climatic changes within a Mediterranean evergreen oak forest (dehesas)

2021 ◽  
Author(s):  
Layla M. San-Emeterio ◽  
Ignacio Pérez-Ramos ◽  
Maria Teresa Domínguez-Núñez ◽  
Francisco Javier González-Vila ◽  
José Antonio González-Pérez
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Technical Assistance ◽  
Isotope Composition ◽  
Climatic Conditions ◽  
Soil Samples ◽  
Tree Canopy ◽  
Analytical Pyrolysis ◽  
Exchangeable Hydrogen ◽  
Evergreen Oak

&lt;p&gt;Soil organic matter (SOM) is composed of multiple components from the living material, such as phenolic compounds, organic acids, lipids, peptides, polyesters, etc. A relevant part of these compounds forms part of supramolecular structures or mineral associations. Non-exchangeable hydrogen in SOM compounds is worth of study as an approach to estimate dynamic processes such as stabilization, mineralization, or biodegradation. The determination of H isotopes in SOMs faces analytical challenges related with e.g., the strength of the H bond, its exchangeability with ambient H from water or the instability of the isotopic analysis [1]. Nonetheless, along with the study of C isotopes, the study of H isotopes may certainly result in a complementary to give some light in this complex system, estimate the fate of organic compounds, and to better understand the link between hydrogen and carbon cycles in SOM [2].&lt;/p&gt;&lt;p&gt;In this communication, we describe and validate a methodology based on analytical pyrolysis for the direct measure of compound-specific H isotope composition (&amp;#948;&lt;sup&gt;2&lt;/sup&gt;H) in soil samples. The technique combines Py-GC with a high-temperature conversion reactor and a continuous flow isotope ratio mass spectrometer (IRMS) (Py-GC-HTC-IRMS).&lt;/p&gt;&lt;p&gt;Composite &lt;em&gt;dehesa&lt;/em&gt; surface (0-10 cm) soil samples (Pozoblanco, C&amp;#243;rdoba, Spain) were taken from four forced climatic treatment plots representing warming (W), drought (D), its combination (W+D), and control (D), installed in two different habitats: under evergreen oak canopy and in the open pasture. The samples were analysed in triplicate by conventional analytical pyrolysis (Py-GC/MS) and in parallel for &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H Py-CSIA using the same chromatographic conditions and separation column type.&lt;/p&gt;&lt;p&gt;Up to 32 compounds were identified by Py-GC/MS, which H isotope composition corresponded presumably to non-exchangeable H, and with origin mainly from lignin (G- and S- units) and lipids. The H isotope composition showed an estimated average of -55 &amp;#8240; &amp;#177; 7.09 for G-lignin units, -64 &amp;#8240; &amp;#177; 8.64 S-lignin units and lighter -112 &amp;#8240; &amp;#177; 4.32 for fatty acids (-109 &amp;#8240; &amp;#177; 3.65) and the n-alkane series (C-19 to C-31). Significant differences are reportedly driven by the differences in habitat: more depleted &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H values were found in SOM produced in the open pasture than under the tree canopy. In addition, a &amp;#948;&lt;sup&gt;2&lt;/sup&gt;H enrichment is observed for lignin-derived compounds in SOM under the W+D treatment.&lt;/p&gt;&lt;p&gt;The technique used and tested is expected to bring novelty results in relation to the processes affecting the isotopic composition of non-exchangeable hydrogen exerted by climatic treatments on diverse SOM specific compounds. Besides presenting the analytical challenges that are faced, we will discuss the effects of canopy and climatic treatments to tackle potential harsh climatic conditions as predicted, especially in Mediterranean areas.&amp;#160;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgement:&lt;/strong&gt; INTERCARBON project (CGL2016-78937-R), DECAFUN (CGL2015-70123-R). MICIU for funding FPI research grants (BES-2017-07968). Mrs Desir&amp;#233; Monis, Mrs Alba M. Carmona &amp; Mr Eduardo Guti&amp;#233;rrez Gonz&amp;#225;lez are acknowledged for technical assistance.&lt;/p&gt;&lt;p&gt;[1] Paul, A. et al (2016). &lt;em&gt;Biogeosciences, 13&lt;/em&gt;, 6587&amp;#8211;6598.&lt;/p&gt;&lt;p&gt;[2] Seki, O. et al (2010). &lt;em&gt;Geochimica et Cosmochimica Acta,&amp;#160;74&lt;/em&gt;(2), 599-613.&lt;/p&gt;

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