Search

Anthracological analyses of charcoal samples retrieved from Pit 16 of Perdigões (Reguengos de Monsaraz, Portugal), a secondary deposition of cremated human remains dated back to the middle of the 3rd millennium BC, enabled the identification of 7 different taxa: Olea europaea, Quercus spp. (evergreen), Pinus pinaster, Fraxinus cf. angustifolia, Arbutus unedo, Cistus sp. and Fabaceae. All taxa are characteristic of both deciduous and evergreen Mediterranean vegetation, and this data might indicate that the gathering of woods employed for the human cremation/s occurred either on site, or in its vicinity. However, considering both the large distribution of the identified taxa and data about human mobility, it is not possible to conclusively determine the origin of the wood used in the cremation(s). Chemometric analysis were carried out to estimate the absolute burning temperature of woods employed for the human cremation/s. An in-lab charcoal reference collection was created by burning sound wood samples of the three main taxa identified from Pit 16, Olea europaea var. sylvestris, Quercus suber (evergreen type) and Pinus pinaster, at temperatures between 350 and 600 °C. The archaeological charcoal samples and the charcoal reference collection were chemically characterized by using mid-infrared (MIR) spectroscopy in the 1800–400 cm-1 range, and Partial Least Squares (PLS) regression method was used to build calibration models to predict the absolute combustion temperature of the archaeological woods. Results showed successful PLS forecasting of burn temperature for each taxon (significant (P <0.05) cross validation coefficients). The anthracological and chemometric analysis evidenced differences between the taxa coming from the two stratigraphic units within the Pit, SUs 72 and 74, suggesting that they may come from two different pyres or two different depositional moments. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Ciências Agrárias is the property of Sociedade de Ciencias Agrarias de Portugal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The role of laccase SilA produced by Streptomyces ipomoeae CECT 3341 in lignocellulose degradation was investigated. A comparison of the properties and activities of a laccase-negative mutant strain (SilA−) with that of the wild-type was studied in terms of their ability to degrade lignin from grass lignocellulose. The yields of solubilized lignin (acid precipitable polymeric lignin, APPL) obtained from wheat straw by both strains in Solid State Fermentation (SSF) conditions demonstrated the importance of SilA laccase in lignin degradation with the wild-type showing 5-fold more APPL produced compared with the mutant strain (SilA−). Analytical pyrolysis and FT-IR (Fourier Transform Infrared Spectroscopy) confirmed that the APPL obtained from the substrate fermented by wild-type strain was dominated by lignin derived methoxyphenols whereas those from SilA− and control APPLs were composed mainly of polysaccharides. This is the first report highlighting the role of this laccase in lignin degradation. [ABSTRACT FROM AUTHOR]

Forest fires cause immediate and lasting environmental impacts in soil organic matter (SOM) by modifying existing chemical structures, forming new ones, or adding/removing materials such as fresh or charred biomass. In this paper, the information provided by analytical pyrolysis (Py-GC/MS) of whole soil samples and two particle-size fractions (coarse and fine) is analysed in a sandy soil from a typical Mediterranean oak forest close to Doñana National Park (Southwest Spain) that was affected by a severe wildfire. The pyrograms from unburnt whole soil samples show a prevalence of compounds derived from polysaccharides, proteins and lignin, whereas in pyrograms from burnt soils lignin markers prevail followed by proteins, alkylaromatic and polycyclic aromatic hydrocarbons. In fact, it seems clear that fire preferentially removes thermolabile biogenic materials with a concomitant selective preservation of lignin. Concerning particle size fractions, SOM in the unburnt coarse fraction had a major impact on vegetation, whereas the fine fraction consisted of comparatively humified SOM with lignin degradation and microbial-derived compounds. The pyrolysis products from the burnt soil coarse fraction revealed post-fire litter inputs from stressed vegetation, whereas the fine fraction shares chemical characteristics with those from the unburnt soil, with additional signs of fire alteration (less labile carbohydrate structures and higher relative abundance of PAHs). Alkane changes observed in the carbon preference index indicate that fire affected SOM mostly in the fine fraction, whereas the short/long chain ratio points to the cracking of long-chain alkanes. In addition, when plotting O/C and H/C values in a Van Krevelen diagram, additional information about the main chemical modifications produced by fire in SOM are described, including condensation (oxidation and hydrogenation paralleling) and dealkylation (associated with oxidation and dehydrogenation) processes. This is the first time that Py-GC/MS molecular information from soil samples is analysed using a Van Krevelen graphical approach and together with other classic geochemical proxies it proves to be a valuable and intuitive tool in facilitating the interpretation of complex geochemical data. [ABSTRACT FROM AUTHOR]

BACKGROUND Environmental, economic and safety challenges motivate shift towards safer materials for food packaging. New bioactive packaging techniques, i.e. addition of essential plant oils ( EOs), are gaining attention by creating barriers to protect products from spoilage. Analytical pyrolysis gas chromatography-mass spectrometry (Py- GC-MS) was used to fingerprint a bioactive polylactic acid ( PLA) with polybutylene succinate ( PBS) (950 g kg−1:50 g kg−1) film extruded with variable quantities (0, 20, 50 and 100 g kg−1) of Origanum vulgare EO. RESULTS Main PLA: PBS pyrolysis products were lactide enantiomers and monomer units from the major PLA fraction and succinic acid anhydride from the PBS fraction. Oregano EO pyrolysis released cymene, terpinene and thymol/carvacrol peaks as diagnostic peaks for EO. In fact, linear correlation coefficients better than 0.950 R2 value ( P < 0.001) were found between the chromatographic area of the diagnostic peaks and the amount of oregano EO in the bioplastic. CONCLUSION The pyrolytic behaviour of a bio-based active package polymer including EO is studied in detail. Identified diagnostic compounds provide a tool to monitor the quantity of EO incorporated into the PLA:PBS polymeric matrix. Analytical pyrolysis is proposed as a rapid technique for the identification and quantification of additives within bio-based plastic matrices. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The relationship between soil organic matter (SOM) content and organic molecular assemblages ( n-alkane/alkenes pairs and n-fatty acids) with soil water repellency (WR) in different sieve fractions (1-2, 0·25-1, 0·05-0·5 and <0·05 mm) was studied in sandy soils from the Doñana National Park (SW Spain) under four vegetation species: Quercus suber (QS), Pteridium aquilinum (PA), Pinus pinea (PP) and Halimium halimifolium (HH). The severity of soil WR [assessed according to the water drop penetration time (WDPT) test] was ordered according to the sequence QS > PA > PP > HH. A positive correlation was found between soil WR from each sieve fraction and SOM content. Most severe soil WR was detected in QS for all sieve fractions, followed by the finer fractions (<0·05 mm) from PA, PP and HH samples. The finer fraction had the highest SOM content, ranging between 20·9% (PP) and 46·9% (QS). Coarser PA, PP and HH soil fractions (1-2 mm) showed the highest long-chain-even C numbered fatty acids in the order PP > PA > HH. A significant correlation was observed between SOM content and the severity of soil WR in QS samples and finer fractions of soil under other vegetation (PA, PP and HH). Coarser fractions (1-2 mm) from PP, PA and HH 1-2 mm sieve fractions showed high severity of WR and relatively low SOM contents that could be explained by a low degree of evolution of the organic residues as seen by analytical pyrolysis, that is, higher alkane/alkene carbon preference index values and the presence of a higher diversity of fatty acid structures. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

BACKGROUND Pyrolysis-compound specific isotopic analysis (Py- CSIA: Py- GC-( FID)-C- IRMS) is a relatively novel technique that allows on-line quantification of stable isotope proportions in chromatographically separated products released by pyrolysis. Validation of the Py- CSIA technique is compulsory for molecular traceability in basic and applied research. In this work, commercial sucrose from C4 (sugarcane) and C3 (sugarbeet) photosystem plants and admixtures were studied using analytical pyrolysis (Py- GC/ MS), bulk δ 13C IRMS and δ 13C Py- CSIA. RESULTS Major pyrolysis compounds were furfural (F), furfural-5-hydroxymethyl ( HMF) and levoglucosan ( LV). Bulk and main pyrolysis compound δ 13C (‰) values were dependent on plant origin: C3 (F, −24.65 ± 0.89; HMF, −22.07 ± 0.41‰; LV, −21.74 ± 0.17‰) and C4 (F, −14.35 ± 0.89‰; HMF, −11.22 ± 0.54‰; LV, −11.44 ± 1.26‰). Significant regressions were obtained for δ 13C of bulk and pyrolysis compounds in C3 and C4 admixtures. Furfural (F) was found 13C depleted with respect to bulk and HMF and LV, indicating the incorporation of the light carbon atom in position 6 of carbohydrates in the furan ring after pyrolysis. CONCLUSION This is the first detailed report on the δ 13C signature of major pyrolytically generated carbohydrate-derived molecules. The information provided by Py- CSIA is valuable for identifying source marker compounds of use in food science/fraud detection or in environmental research. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Soil water repellency (hydrophobicity) prevents water from wetting or infiltrating soils, triggering changes in the ecosystems. This physical property is directly correlated to the erodibility grade of a soil. Wildfire events may develop, enhance, or destroy soil hydrophobicity, modifying the erodibility grade of a soil and increasing the loss of its most reactive layer (organic matter). To assess the main organic family of compounds (biomarkers) surrogates to fire-induced water repellency, a study was carried out on a fire-affected soil under eucalyptus canopy at two depths (0–2 and 2–5 cm) from Portugal. The potential soil water repellency was measured using the water drop penetration time (WDPT) test. The molecular characterization of hydrophobic biomarkers was carried out using analytical pyrolysis (Py-GC/MS) in combination with multivariate statistical analysis (PCA, MLR). The upper burned soil layer (0–2 cm) displayed a significant contribution of fresh biomass (lignin and polysaccharides), while the deepest (2–5 cm) one showed more humified organic matter (lipids). The soil hydrophobicity was directly correlated to non-polar organic compounds, such as lipids and polycyclic aromatic hydrocarbons (PAHs), and inversely to unspecific aromatic compounds. The combination of mass spectrometry techniques and chemometric analysis allowed obtaining a preliminary forecast model of hydrophobicity degree in fire-affected soil samples under eucalyptus canopy. This analytical approach opens the door to developing more sensitive mathematical models using molecular organic compounds to predict the alteration of hydrophobicity and other soil physical properties induced by fires. [ABSTRACT FROM AUTHOR]

The knowledge of the isotopic composition of virgin olive oil (VOO) allows the evaluation of authenticity and geographical origin, being an important tool against fraud. This study aimed to assess if VOOs produced in three Mediterranean regions could be discriminated on the basis of multivariate statistical analysis of geoclimatic and isotopic data. A total of 138 geo-referenced VOO samples from Portugal, France and Turkey from two different cultivation years were collected. The isotopic composition (δ13C, δ2H and δ18O) of VOOs was obtained using an elemental analyzer coupled to an isotope ratio mass spectrometer (EA-IRMS). One-way analysis of variance for δ13C, δ2H and δ18O showed some significant differences either between crop years or geoclimatic conditions. Based on multiple regression analyses using meteorological and geographical parameters, a meteoric water line for olive oil from Portugal, France and Turkey, in two harvest years, were created to assess the impact of climate change on their δ2H and δ18O values. Principal component analysis and Linear Discriminant Analysis, used to sort samples according to geoclimatic origin, performed best for French and Portuguese olive oils. In light of the results, multivariate isotopic analysis of VOO samples may discriminate not only between geoclimatic regions but also among cultivation years. [ABSTRACT FROM AUTHOR]

Changes in climatic and environmental conditions can affect both, plant chemical and isotope composition. Therefore, biomass carbon isotope composition is frequently used to gain information about the environmental conditions at the time a plant was growing [1]. In this field, the majority of studies use isotope values obtained from bulk samples. However, these values are a weighed mean average of the different plant compounds. The Isotopic characterization of individual biogeochemical compounds represents a relevant analytical advance able to differentiate the isotopic composition of the main plant components i.e. polysaccharides, lignin, polypeptides, lipids and waxes, etc.Here, we investigate the link between molecular and isotope composition of bark from three Eucalyptus species (E. grandis, E. dunni and a hybrid E. grandis x E. dunni) using Py-CSIA. Bulk samples and lignin extracted were analysed by Py-CSIA; this technique, although not widely used, has been previously developed and applied, with different variants [2-7], to characterize plant products including lignin [8], sugars [9] and terpenes [10].Our results support the idea that the pyrolysis compound specific isotope analysis (Py-CSIA) can provide valuable and accurate isotopic fingerprinting of biomass. Despite that wood/bark from different origins provide very similar pyrolysis pattern, isotopic composition of relevant specific compounds can make the difference giving additional valuable information.[1] Michenerand Lajtha (Eds). Stable Isotopes in Ecology and Environmental Science (2nd Ed.) Blackwell Publishing Ltd (2007) 566p.[2] Gonñi and Eglinton, J. High Resol. Chromat. 17 (1994), 476.[3] Pulchan et al., J. Anal. Appl. Pyrolysis 42 (1997), 135.[4] Gleixner and Schmidt. In Nitrogen-containing Macromolecules in the Bio- and Geosphere. Stankiewicz and van Berger (Eds), ACS Symposium Series 707 (1998), pp. 34–46.[5] Gleixner et al. Rapid Commun. Mass Spectrom. 13 (1999) 1278.[6] Schulten and Gleixner Water Res. 33 (1999) 2489.[7] Gleixner et al. Organic Geochemistry 33 (2002) 357.[8] Steinbeiss et al. J. Anal. Appl. Pyrolysis 75 (2006) 19.[9] González-Pérez et al. J. Sci. Food Agric. 96 (2016) 948.[10] Llana-Ruíz-Cabello et al. J. Chrom A 1525 (2017) 145. [ABSTRACT FROM AUTHOR]

The replacement of native European beech forests ( Fagus sylvatica ) with Scots pine ( Pinus sylvestris ) afforestation may exert changes in soil properties, particularly with respect to soil organic matter (SOM). Stable isotope composition of light elements ( δ 13 C, δ 15 N) in soils are known proxies for the characterisation of SOM genesis and dynamics. In this research, C and N isotope composition of organic layers, classified as OL (fresh litter), OF (fragmented litter) and OH (humified litter), and the first mineral horizon (Ah) from what was, originally, a beech domain and from a domain of afforestation with pine were analysed by using EA–IRMS. Additionally, C and N isotope signatures were studied in complete soil profiles that were representative of each forest. Pine OL was found to be 13 C enriched ( δ 13 C = −28.08 ± 0.49‰) compared with beech (−29.87 ± 0.27‰). Along the soil profile, C isotope composition mirrors that of the standing vegetation down to the first mineral Ah horizon, with significantly higher δ 13 C in pine than in beech. Deeper in the soil, from the eluvial E horizon, no significant δ 13 C differences were found between soils, indicating a limited pine influence in depth, years after afforestation. Pine litter tended to be 15 N enriched (δ 15 N = 4.43 ± 2.65‰) compared to beech (1.43 ± 2.80‰). Along the soil profile, a consistent 15 N enrichment was observed with depth in the organic layers (O–layers) down to OH. No significant δ 15 N differences were found in the mineral horizons between soils, except for the E horizon that showed a lower δ 15 N in the beech than in the pine profile. This N trend could be explained by 1) a progressive biomass alteration and a concomitant 15 N–enrichment being, in general, more pronounced in O–layers under alien pine than under beech, and 2) migration of more humified SOM forms from eluvial to deeper Bhs horizons, causing a relative accumulation of 15 N–depleted SOM in the beechwood E horizon. The accumulation of fungal and root biomass in pinewood OF horizons could be reflected in its 15 N–depleted signature. [ABSTRACT FROM AUTHOR]