scholarly journals Constraining the role of iron in environmental nitrogen transformations. Dual stable isotope systematics of abiotic NO2- reduction by Fe(II) and its production of N2O

2015 ◽  
Author(s):  
David Johnston ◽  
Scott David Wankel ◽  
Carolyn Buchwald ◽  
Colleen Hansel
Keyword(s):  
Stable Isotope ◽  
Nitrogen Transformations ◽  
Isotope Systematics

scholarly journals More than redox, biological organic ligands control iron isotope fractionation in the riparian wetland

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elaheh Lotfi-Kalahroodi ◽  
Anne-Catherine Pierson-Wickmann ◽  
Olivier Rouxel ◽  
Rémi Marsac ◽  
Martine Bouhnik-Le Coz ◽  
...  
Keyword(s):  
Redox Reactions ◽  
Isotope Fractionation ◽  
Isotopic Fractionation ◽  
Isotopic Signature ◽  
Organic Ligands ◽  
Riparian Wetland ◽  
Fe Isotopes ◽  
Preferential Binding ◽  
Isotope Systematics

AbstractAlthough redox reactions are recognized to fractionate iron (Fe) isotopes, the dominant mechanisms controlling the Fe isotope fractionation and notably the role of organic matter (OM) are still debated. Here, we demonstrate how binding to organic ligands governs Fe isotope fractionation beyond that arising from redox reactions. The reductive biodissolution of soil Fe(III) enriched the solution in light Fe isotopes, whereas, with the extended reduction, the preferential binding of heavy Fe isotopes to large biological organic ligands enriched the solution in heavy Fe isotopes. Under oxic conditions, the aggregation/sedimentation of Fe(III) nano-oxides with OM resulted in an initial enrichment of the solution in light Fe isotopes. However, heavy Fe isotopes progressively dominate the solution composition in response to their binding with large biologically-derived organic ligands. Confronted with field data, these results demonstrate that Fe isotope systematics in wetlands are controlled by the OM flux, masking Fe isotope fractionation arising from redox reactions. This work sheds light on an overseen aspect of Fe isotopic fractionation and calls for a reevaluation of the parameters controlling the Fe isotopes fractionation to clarify the interpretation of the Fe isotopic signature.

Diet of ancient Egyptians inferred from stable isotope systematics

2014 ◽  
Vol 46 ◽  
pp. 114-124 ◽  
Author(s):  
Alexandra Touzeau ◽  
Romain Amiot ◽  
Janne Blichert-Toft ◽  
Jean-Pierre Flandrois ◽  
François Fourel ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Isotope Systematics

scholarly journals Barium stable isotopes as a fingerprint of biological cycling in the Amazon River basin

2020 ◽  
Vol 17 (23) ◽  
pp. 5989-6015
Author(s):  
Quentin Charbonnier ◽  
Julien Bouchez ◽  
Jérôme Gaillardet ◽  
Éric Gayer
Keyword(s):  
Organic Matter ◽  
Stable Isotope ◽  
Trace Element ◽  
Isotope Composition ◽  
Silicate Weathering ◽  
Biological Cycling ◽  
Biological Uptake ◽  
Dissolved Load ◽  
Silicate Rocks

Abstract. The biological cycle of rock-derived nutrients on the continents is a major component of element transfer between the Earth's surface compartments, but its magnitude currently remains elusive. The use of the stable isotope composition of rock-derived nutrients, which can be fractionated during biological uptake, provides a promising path forward with respect to quantifying biological cycling and its overall contribution to global element cycling. In this paper, we rely on the nutrient-like behaviour of the trace element barium (Ba) and use its elemental and stable isotope compositions in dissolved and sediment load river samples to investigate biological cycling in the Amazon Basin. From these measurements, we show that dissolved Ba mainly derives from silicate rocks, and a correlation between dissolved Ba and K abundances suggests that biological cycling plays a role in the Ba river budget. Furthermore, the isotope composition of Ba (δ138Ba) in the dissolved load was found to be significantly different from that of the parent silicate rocks, implying that dissolved Ba isotopic signatures are affected by (i) the precipitation of soil-forming secondary phases as well as (ii) biological uptake and release from dead organic matter. Results from an isotope mass balance method applied to the river dissolved load data indicate that, after its release to solution by rock weathering, Ba is partitioned between the river dissolved load, secondary weathering products (such as those found in soils and river sediments), and the biota. In most sub-catchments of the Amazon, river Ba abundances and isotope compositions are significantly affected by biological cycling. Relationships between estimates of Ba cycled through biota and independent metrics of ecosystem dynamics (such as gross primary production and terrestrial ecosystem respiration) allow us to discuss the role of environmental parameters such as climate or erosion rates on the biological cycling of Ba and, by extension, the role of major rock-derived nutrients. In addition, catchment-scale mass and isotope budgets of Ba show that the measured riverine export of Ba is lower than the estimated delivery of Ba to the Earth surface through rock alteration. This indicates the existence of a missing Ba component, which we attribute to the formation of Ba-bearing particulate organics (possibly accumulating as soil organic matter or currently growing biomass within the catchments) and to organic-bound Ba exported as “unsampled” river particulate organic matter. Given our findings on the trace element Ba, we explore whether the river fluxes of most major rock-derived nutrients (K, Mg, Ca) might also be significantly affected by biological uptake or release. A first-order correction of river-derived silicate weathering fluxes from biological cycling shows that the carbon dioxide (CO2) consumption by silicate weathering at the mouth of the Amazon could be several times higher than the previously reported value of 13 × 109 mol CO2 yr−1 (Gaillardet et al., 1997). Overall, our study clearly shows that the chemical and isotope compositions of rivers in the Amazon – and most likely in other large river basins – bear a biological imprint, thereby challenging common assumptions made in weathering studies.

The Role of Fruits and Insects in the Nutrition of Frugivorous Bats: Evaluating the Use of Stable Isotope Models1

Biotropica ◽  
2001 ◽  
Vol 33 (3) ◽  
pp. 520-528 ◽  
Author(s):  
L. Gerardo Herrera M. ◽  
Keith A. Hobson ◽  
Adriana Manzo A ◽  
Daniel Estrada B ◽  
Victor Sanchez-Cordero ◽  
...  
Keyword(s):  
Stable Isotope

scholarly journals Stable isotope probing of hypoxic toluene degradation at the Siklós aquifer reveals prominent role of Rhodocyclaceae

2018 ◽  
Vol 94 (6) ◽  
Author(s):  
András Táncsics ◽  
Anna Róza Szalay ◽  
Milan Farkas ◽  
Tibor Benedek ◽  
Sándor Szoboszlay ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Probing ◽  
Toluene Degradation

Fate of commercial pellets and role of natural productivity in giant gourami ponds using stable isotope analyses

Aquaculture ◽  
2022 ◽  
Vol 547 ◽  
pp. 737484
Author(s):  
Simon Pouil ◽  
Jean-Michel Mortillaro ◽  
Reza Samsudin ◽  
Domenico Caruso ◽  
Anang Hari Kristanto ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Stable Isotope Analyses ◽  
Natural Productivity ◽  
Isotope Analyses

Stable Isotope Records from Greenland Deep Ice Cores: The Climate Signal and the Role of Diffusion

1999 ◽  
pp. 89-107 ◽  
Author(s):  
Sigfús J. Johnsen ◽  
H. B. Clausen ◽  
Jean Jouzel ◽  
Jakob Schwander ◽  
Árny E. Sveinbjörnsdóttir ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Ice Cores ◽  
Climate Signal
Sign in / Sign up

Export Citation Format

Share Document