nitrogen isotope fractionation
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2021 ◽  
Vol 55 (8) ◽  
pp. 5537-5546
Author(s):  
Ciara K. Asamoto ◽  
Kaitlin R. Rempfert ◽  
Victoria H. Luu ◽  
Adam D. Younkin ◽  
Sebastian H. Kopf

2020 ◽  
Vol 6 (9) ◽  
pp. eaay3440 ◽  
Author(s):  
Eva E. Stüeken ◽  
Christopher Tino ◽  
Gernot Arp ◽  
Dietmar Jung ◽  
Timothy W. Lyons

High-pH alkaline lakes are among the most productive ecosystems on Earth and prime targets in the search for life on Mars; however, a robust proxy for such settings does not yet exist. Nitrogen isotope fractionation resulting from NH3 volatilization at high pH has the potential to fill this gap. To validate this idea, we analyzed samples from the Nördlinger Ries, a Miocene impact crater lake that displayed pH values up to 9.8 as inferred from mineralogy and aqueous modeling. Our data show a peak in δ15N of +17‰ in the most alkaline facies, followed by a gradual decline to around +5‰, concurrent with the proposed decline in pH, highlighting the utility of nitrogen isotopes as a proxy for high-pH conditions. In combination with independent mineralogical indicators for high alkalinity, nitrogen isotopes can provide much-needed quantitative constraints on ancient atmospheric Pco2 (partial pressure of CO2) and thus climatic controls on early Earth and Mars.


2020 ◽  
Vol 150 ◽  
pp. 110745 ◽  
Author(s):  
Richard J. Pruell ◽  
Bryan K. Taplin ◽  
Autumn J. Oczkowski ◽  
Jason S. Grear ◽  
Wilson G. Mendoza ◽  
...  

2020 ◽  
Author(s):  
Yuan Li ◽  
Lanlan Shi ◽  
T Kagoshima ◽  
Y Sano ◽  
Z Gao ◽  
...  

2020 ◽  
Author(s):  
Caterina Melai ◽  
Daniel Frost ◽  
Yoshihiro Furukawa ◽  
Akizumi Ishida ◽  
Akio Suzuki

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Mathieu Sebilo ◽  
Giovanni Aloisi ◽  
Bernhard Mayer ◽  
Emilie Perrin ◽  
Véronique Vaury ◽  
...  

AbstractThe microbial reduction of nitrate, via nitrite into gaseous di-nitrogen (denitrification) plays a major role in nitrogen removal from aquatic ecosystems. Natural abundance stable isotope measurements can reveal insights into the dynamics of production and consumption of nitrite during denitrification. In this study, batch experiments with environmental bacterial communities were used to investigate variations of concentrations and isotope compositions of both nitrite and nitrate under anoxic conditions. To this end, denitrification experiments were carried out with nitrite or nitrate as sole electron acceptors at two substrate levels respectively. For experiments with nitrate as substrate, where the intermediate compound nitrite is both substrate and product of denitrification, calculations of the extent of isotope fractionation were conducted using a non-steady state model capable of tracing chemical and isotope kinetics during denitrification. This study showed that nitrogen isotope fractionation was lower during the use of nitrite as substrate (ε = −4.2 and −4.5‰ for both treatments) as compared to experiments where nitrite was produced as an intermediate during nitrate reduction (ε = −10 and −15‰ for both treatments). This discrepancy might be due to isotopic fractionation within the membrane of denitrifiers. Moreover, our results confirmed previously observed rapid biotic oxygen isotope exchange between nitrite and water.


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