scholarly journals Thawing Yedoma permafrost is a neglected nitrous oxide source

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
M. E. Marushchak ◽  
J. Kerttula ◽  
K. Diáková ◽  
A. Faguet ◽  
J. Gil ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Structural Changes ◽  
N Cycling ◽  
Climate Feedback ◽  
The Arctic ◽  
Substantial Part ◽  
N Availability ◽  
Disturbed Areas ◽  
C And N ◽  
Positive Climate

AbstractIn contrast to the well-recognized permafrost carbon (C) feedback to climate change, the fate of permafrost nitrogen (N) after thaw is poorly understood. According to mounting evidence, part of the N liberated from permafrost may be released to the atmosphere as the strong greenhouse gas (GHG) nitrous oxide (N2O). Here, we report post-thaw N2O release from late Pleistocene permafrost deposits called Yedoma, which store a substantial part of permafrost C and N and are highly vulnerable to thaw. While freshly thawed, unvegetated Yedoma in disturbed areas emit little N2O, emissions increase within few years after stabilization, drying and revegetation with grasses to high rates (548 (133–6286) μg N m−2 day−1; median with (range)), exceeding by 1–2 orders of magnitude the typical rates from permafrost-affected soils. Using targeted metagenomics of key N cycling genes, we link the increase in in situ N2O emissions with structural changes of the microbial community responsible for N cycling. Our results highlight the importance of extra N availability from thawing Yedoma permafrost, causing a positive climate feedback from the Arctic in the form of N2O emissions.

Nitrous oxide emissions from red clover and winter wheat residues depend on interacting effects of distribution, soil N availability and moisture level

2021 ◽  
Author(s):  
Arezoo Taghizadeh-Toosi ◽  
Baldur Janz ◽  
Rodrigo Labouriau ◽  
Jørgen E. Olesen ◽  
Klaus Butterbach-Bahl ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Winter Wheat ◽  
Red Clover ◽  
Moisture Level ◽  
Nitrous Oxide Emissions ◽  
N Availability ◽  
Soil N ◽  
Soil N Availability

Clomazone improves the interactions between soil microbes and affects C and N cycling functions

2021 ◽  
Vol 770 ◽  
pp. 144730
Author(s):  
Lili Rong ◽  
Xiaohu Wu ◽  
Jun Xu ◽  
Fengshou Dong ◽  
Xingang Liu ◽  
...  
Keyword(s):  
Soil Microbes ◽  
N Cycling ◽  
C And N ◽  
C And N Cycling

Comparison of carbon and nitrogen storage in mineral soils of graminoid and shrub tundra sites, western Greenland

2016 ◽  
Vol 2 (4) ◽  
pp. 165-182 ◽  
Author(s):  
Chelsea L. Petrenko ◽  
Julia Bradley-Cook ◽  
Emily M. Lacroix ◽  
Andrew J. Friedland ◽  
Ross A. Virginia
Keyword(s):  
Vegetation Type ◽  
Mineral Soil ◽  
Biotic Interactions ◽  
The Arctic ◽  
Soil C ◽  
N Storage ◽  
C Storage ◽  
Arctic Soils ◽  
C Pools ◽  
C And N

Shrub species are expanding across the Arctic in response to climate change and biotic interactions. Changes in belowground carbon (C) and nitrogen (N) storage are of global importance because Arctic soils store approximately half of global soil C. We collected 10 (60 cm) soil cores each from graminoid- and shrub-dominated soils in western Greenland and determined soil texture, pH, C and N pools, and C:N ratios by depth for the mineral soil. To investigate the relative chemical stability of soil C between vegetation types, we employed a novel sequential extraction method for measuring organo-mineral C pools of increasing bond strength. We found that (i) mineral soil C and N storage was significantly greater under graminoids than shrubs (29.0 ± 1.8 versus 22.5 ± 3.0 kg·C·m−2 and 1.9 ± .12 versus 1.4 ± 1.9 kg·N·m−2), (ii) chemical mechanisms of C storage in the organo-mineral soil fraction did not differ between graminoid and shrub soils, and (iii) weak adsorption to mineral surfaces accounted for 40%–60% of C storage in organo-mineral fractions — a pool that is relatively sensitive to environmental disturbance. Differences in these C pools suggest that rates of C accumulation and retention differ by vegetation type, which could have implications for predicting future soil C pool storage.

Nitrous oxide production in two forested watersheds exhibiting symptoms of nitrogen saturation

1998 ◽  
Vol 28 (11) ◽  
pp. 1723-1732 ◽  
Author(s):  
William T Peterjohn ◽  
Richard J McGervey ◽  
Alan J Sexstone ◽  
Martin J Christ ◽  
Cassie J Foster ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Nitrogen Saturation ◽  
N Cycling ◽  
Woody Vegetation ◽  
N Saturation ◽  
Relative Importance ◽  
Forested Watersheds ◽  
Total N ◽  
Nitrous Oxide Production ◽  
Poorly Drained Soils

A major concern about N saturation is that it may increase the production of a strong greenhouse gas, nitrous oxide (N2O). We measured N2O production in two forested watersheds, a young, fertilized forest (WS 3) and an older, unfertilized forest (WS 4), to (i) assess the importance of N2O production in forests showing symptoms of N saturation; (ii) estimate the contribution of chemoautrophic nitrification to total N2O production; and (iii) examine the relative importance of factors that may control N2O production. During the study period, mean monthly rates of N2O production (3.41-11.42 µ N ·m-2·h-1) were consistent with measurements from other well-drained forest soils but were much lower than measurements from N-rich sites with poorly drained soils. Chemoautotrophic nitrification was important in both watersheds, accounting for 60% (WS 3) and 40% (WS 4) of total N2O production. In WS 3, N2O production was enhanced by additions of CaCO3 and may be constrained by low soil pH. In WS 4, N2O production on south-facing slopes was exceptionally low, constrained by low NO3 availability, and associated with a distinct assemblage of woody vegetation. From this observation, we hypothesize that differences in vegetation can influence N cycling rates and susceptibility to N saturation.

Modelling terrestrial nitrous oxide emissions and implications for climate feedback

2012 ◽  
Vol 196 (2) ◽  
pp. 472-488 ◽  
Author(s):  
Xu‐Ri ◽  
I. Colin Prentice ◽  
Renato Spahni ◽  
Hai Shan Niu
Keyword(s):  
Nitrous Oxide ◽  
Climate Feedback ◽  
Nitrous Oxide Emissions

Relationships between C and N availability, substrate age, and natural abundance 13C and 15N signatures of soil microbial biomass in a semiarid climate

2009 ◽  
Vol 41 (8) ◽  
pp. 1605-1611 ◽  
Author(s):  
Jeff S. Coyle ◽  
Paul Dijkstra ◽  
Richard R. Doucett ◽  
Egbert Schwartz ◽  
Stephen C. Hart ◽  
...  
Keyword(s):  
Microbial Biomass ◽  
Soil Microbial Biomass ◽  
Natural Abundance ◽  
N Availability ◽  
Soil Microbial ◽  
Semiarid Climate ◽  
C And N ◽  
Substrate Age

scholarly journals Implications of carbon saturation model structure for simulated nitrogen mineralization dynamics

2014 ◽  
Vol 11 (6) ◽  
pp. 9667-9695 ◽  
Author(s):  
C. M. White ◽  
A. R. Kemanian ◽  
J. P. Kaye
Keyword(s):  
Soil Properties ◽  
N Mineralization ◽  
Storage Capacity ◽  
Clay Content ◽  
N Cycling ◽  
Transfer Efficiency ◽  
Net N Mineralization ◽  
Saturation Ratio ◽  
Carbon Saturation ◽  
C And N

Abstract. Carbon (C) saturation theory suggests that soils have a~limited capacity to stabilize organic C and that this capacity may be regulated by intrinsic soil properties such as clay content and mineralogy. While C saturation theory has advanced our ability to predict soil C stabilization, we only have a weak understanding of how C saturation affects N cycling. In biogeochemical models, C and N cycling are tightly coupled, with C decomposition and respiration driving N mineralization. Thus, changing model structures from non-saturation to C saturation dynamics can change simulated N dynamics. Carbon saturation models proposed in the literature calculate a theoretical maximum C storage capacity of saturating pools based on intrinsic soil properties, such as clay content. The extent to which current C stocks fill the storage capacity of the pool is termed the C saturation ratio, and this ratio is used to regulate either the efficiency or the rate of C transfer from donor to receiving pools. In this study, we evaluated how the method of implementing C saturation and the number of pools in a model affected net N mineralization from decomposing plant residues. In models that use the C saturation ratio to regulate transfer efficiency, C saturation affected N mineralization, while in those in which the C saturation ratio regulates transfer rates, N mineralization was independent of C saturation. When C saturation ratio regulates transfer efficiency, as the saturation ratio increases, the threshold C : N ratio at which positive net N mineralization occurs also increases because more of the C in the residue is respired. In a single-pool model where C saturation ratio regulated the transfer efficiency, predictions of N mineralization from residue inputs were unrealistically high, missing the cycle of N immobilization and mineralization typically seen after the addition of high C : N inputs to soils. A more realistic simulation of N mineralization was achieved simply by adding a second pool to the model to represent short-term storage and turnover of C and N in microbial biomass. These findings increase our understanding of how to couple C saturation and N mineralization models, while offering new hypotheses about the relationship between C saturation and N mineralization that can be tested empirically.

scholarly journals Temporal Patterns and Intra- and Inter-Cellular Variability in Carbon and Nitrogen Assimilation by the Unicellular Cyanobacterium Cyanothece sp. ATCC 51142

2021 ◽  
Vol 12 ◽  
Author(s):  
Lubos Polerecky ◽  
Takako Masuda ◽  
Meri Eichner ◽  
Sophie Rabouille ◽  
Marie Vancová ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Population Heterogeneity ◽  
N Availability ◽  
Imaging Data ◽  
Turnover Rates ◽  
Unicellular Cyanobacterium ◽  
Phytoplankton Communities ◽  
N Assimilation ◽  
Wide Range ◽  
C And N

Unicellular nitrogen fixing cyanobacteria (UCYN) are abundant members of phytoplankton communities in a wide range of marine environments, including those with rapidly changing nitrogen (N) concentrations. We hypothesized that differences in N availability (N2 vs. combined N) would cause UCYN to shift strategies of intracellular N and C allocation. We used transmission electron microscopy and nanoscale secondary ion mass spectrometry imaging to track assimilation and intracellular allocation of 13C-labeled CO2 and 15N-labeled N2 or NO3 at different periods across a diel cycle in Cyanothece sp. ATCC 51142. We present new ideas on interpreting these imaging data, including the influences of pre-incubation cellular C and N contents and turnover rates of inclusion bodies. Within cultures growing diazotrophically, distinct subpopulations were detected that fixed N2 at night or in the morning. Additional significant within-population heterogeneity was likely caused by differences in the relative amounts of N assimilated into cyanophycin from sources external and internal to the cells. Whether growing on N2 or NO3, cells prioritized cyanophycin synthesis when N assimilation rates were highest. N assimilation in cells growing on NO3 switched from cyanophycin synthesis to protein synthesis, suggesting that once a cyanophycin quota is met, it is bypassed in favor of protein synthesis. Growth on NO3 also revealed that at night, there is a very low level of CO2 assimilation into polysaccharides simultaneous with their catabolism for protein synthesis. This study revealed multiple, detailed mechanisms underlying C and N management in Cyanothece that facilitate its success in dynamic aquatic environments.

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