This work studies carbon (C) and hydrogen (H) isotope composition of plant biomass and soil organic matter (SOM) in an attempt to assess both, changes exerted by fire and possible inputs of charred materials to the soil after a wildfire. Isotope composition of bulk soil, soil particle size fractions and biomass of the dominant standing vegetation in the area (Quercus suber) from Doñana National Park (SW-Spain) were studied by isotope ratio mass spectrometry (IRMS). SOM C isotope composition indicates the occurrence of two SOM pools with different degree of alteration. Coarse soil fractions (>0.5 mm) were found C depleted with δC values close to those in leaf biomass, pointing to a predominance of poorly transformed SOM. Conversely, fine fractions (<0.1 mm) were found enriched in C as corresponds to a more humified SOM. The fire produced no changes in this trend, although a consistent C enrichment (c. 1‰) was observed in all soil fractions with decreasing size. Concerning H isotopes, the coarse fractions (>0.5 mm) displayed significant lower δH values than the intermediate and fine ones (<0.5 mm), again similar to those in leaf biomass (c. -80‰), whereas the fine fractions were found deuterium (H)-enriched with significant higher δH values (c. 50‰), suggesting physical speciation of H depending on soil particle size. The fire produced a significant H depletion (ΔH c. -10‰) in the finer fractions (<0.1 mm). The study of stable isotope analysis added new information and complements the results obtained by other proxies to better understand the effect of fire on SOM.
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http://dx.doi.org/10.1016/j.scitotenv.2020.141417 | DOI Listing |
Sci Rep
December 2024
College of Mining Engineering, Guizhou University of Engineering Science, Bijie, 551700, China.
The Laurani high-sulfidation epithermal deposit, located in the northeastern Altiplano of Bolivia, is a representative gold-polymetallic deposit linked to the late Miocene volcanic rocks that were formed approximately at about 7.5 Ma. At Laurani, four mineralization stages are defined.
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December 2024
Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States.
Added electrons and holes in semiconducting (nano)materials typically occupy "trap states," which often determine their photophysical properties and chemical reactivity. However, trap states are usually ill-defined, with few insights into their stoichiometry or structure. Our laboratory previously reported that aqueous colloidal TiO nanoparticles prepared from TiCl + HO have two classes of electron trap states, termed and .
View Article and Find Full Text PDFFood Chem
December 2024
Food Quality and Design, Wageningen University & Research, P.O. Box 17, 6700, AA, Wageningen, The Netherlands; School of Agriculture and Food Science, University College Dublin, Dublin 4, Ireland. Electronic address:
This study aims to assess the effects of oven heating on the isotopic ratios of eight formulated wheat-processed products with different gluten-to-starch ratios. Two heating treatments were applied: limited heating in an oven with exposure to 100 °C for a specific time (cooking time-dependent) and extended heating in an oven with exposure to 100 °C, 180 °C and 260 °C for 6 min. Results showed limited heating exposure did not alter the δH and δO in the wheat-processed products.
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December 2024
Ocean Sciences Department, University of California, Santa Cruz, Santa Cruz, CA, USA.
Stable isotopes of carbon (δC) and nitrogen (δN) are commonly employed to reconstruct past change in marine ecosystems and nutrient cycling. However, multiple biogeochemical and physical drivers govern spatiotemporal variability of these isotopic signals, particularly in dynamic coastal systems, complicating interpretation. Here, we coupled a modern multi-year (2010-2019) δC and δN isoscape record from intertidal mussels (Mytilus californianus) with high-resolution ocean model output and satellite chlorophyll-a observations in the California Current System (32°-43° N) to identify major drivers of isotopic variability.
View Article and Find Full Text PDFMar Pollut Bull
December 2024
Centre for Marine Living Resources and Ecology (CMLRE), Kochi, Kerala, India; Central University of Kerala (CUK), Kasargod, Kerala, India.
This study investigated major contributors of the particulate organic matter (POM) using stable isotope ratios of particulate organic carbon (δC) and its relationship with phytoplankton composition during three seasons across six coast-offshore transects in the eastern Arabian Sea (EAS). Results revealed significant spatiotemporal variations, with elevated δC in coastal waters during the winter and summer monsoon (-22.40 ± 1.
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