Permafrost nitrous oxide emissions observed on a landscape scale using the airborne eddy-covariance method

Abstract. The microbial by-product nitrous oxide (N2O), a potent greenhouse gas and ozone depleting substance, has conventionally been assumed to have minimal emissions in permafrost regions. This assumption has been questioned by recent in situ studies which have demonstrated that some geologic features in permafrost may, in fact, have elevated emissions comparable to those of tropical soils. However, these recent studies, along with every known in situ study focused on permafrost N2O fluxes, have used chambers to examine small areas (<50 m2). In late August 2013, we used the airborne eddy-covariance technique to make in situ N2O flux measurements over the North Slope of Alaska from a low-flying aircraft spanning a much larger area: around 310 km2. We observed large variability of N2O fluxes with many areas exhibiting negligible emissions. Still, the daily mean averaged over our flight campaign was 3.8 (2.2–4.7) mg N2O m−2 d−1 with the 90 % confidence interval shown in parentheses. If these measurements are representative of the whole month, then the permafrost areas we observed emitted a total of around 0.04–0.09 g m−2 for August, which is comparable to what is typically assumed to be the upper limit of yearly emissions for these regions.

Download Full-text

Permafrost Nitrous Oxide Emissions Observed on a Landscape Scale Using Airborne Eddy Covariance Method

10.5194/acp-2018-1108 ◽

2018 ◽

Author(s):

Jordan Wilkerson ◽

Ronald Dobosy ◽

David S. Sayres ◽

Claire Healy ◽

Edward Dumas ◽

...

Keyword(s):

Nitrous Oxide ◽

Tropical Soils ◽

Landscape Scale ◽

Nitrous Oxide Emissions ◽

Eddy Covariance Method ◽

Small Areas ◽

In Situ Study ◽

Ozone Depleting Substance ◽

Permafrost Regions

Download Full-text

Comments on “Permafrost Nitrous Oxide Emissions Observed on a Landscape Scale Using Airborne Eddy Covariance Method” by Wilkerson et al.

10.5194/acp-2018-1108-rc2 ◽

2018 ◽

Author(s):

Anonymous

Keyword(s):

Nitrous Oxide ◽

Eddy Covariance ◽

Landscape Scale ◽

Nitrous Oxide Emissions ◽

Eddy Covariance Method

Download Full-text

Nitrous oxide emissions from a beech forest floor measured by eddy covariance and soil enclosure techniques

Biogeosciences ◽

10.5194/bg-2-377-2005 ◽

2005 ◽

Vol 2 (4) ◽

pp. 377-387 ◽

Cited By ~ 49

Author(s):

M. Pihlatie ◽

J. Rinne ◽

P. Ambus ◽

K. Pilegaard ◽

J. R. Dorsey ◽

...

Keyword(s):

Nitrous Oxide ◽

Spatial Variability ◽

Eddy Covariance ◽

Temporal Variability ◽

Nitrous Oxide Emissions ◽

Small Scale ◽

N2o Emissions ◽

Ecosystem Level ◽

N2o Fluxes ◽

Trunk Space

Abstract. Spring time nitrous oxide (N2O) emissions from an old beech (Fagus sylvatica L.) forest were measured with eddy covariance (EC) and chamber techniques. The aim was to obtain information on the spatial and temporal variability in N2O emissions and link the emissions to soil environmental parameters. Mean N2O fluxes over the five week measurement period were 5.6±1.1, 10±1 and 16±11 μg N m−2 h−1 from EC, automatic chamber and manual chambers, respectively. High temporal variability characterized the EC fluxes in the trunk-space. To reduce this variability, resulting mostly from random uncertainty due to measuring fluxes close to the detection limit, we averaged the fluxes over one day periods. The variability in the chamber measurements was much smaller and dominated by high small scale spatial variability. The highest emissions measured by the EC method occurred during the first week of May when the trees were leafing and the soil moisture content was at its highest. If chamber techniques are used to estimate ecosystem level N2O emissions from forest soils, placement of the chambers should be considered carefully to cover the spatial variability in the soil N2O emissions. The EC technique, applied in this study, is a promising alternative tool to measure ecosystem level N2O fluxes in forest ecosystems. To our knowledge, this is the first study to demonstrate that the EC technique can be used to measure N2O fluxes in the trunk-space of a forest.

Download Full-text

Nitrous oxide emissions from maize–wheat field during 4 successive years in the North China Plain

Biogeosciences ◽

10.5194/bg-11-1717-2014 ◽

2014 ◽

Vol 11 (7) ◽

pp. 1717-1726 ◽

Cited By ~ 20

Author(s):

Y. Zhang ◽

Y. Mu ◽

Y. Zhou ◽

J. Liu ◽

C. Zhang

Keyword(s):

Nitrous Oxide ◽

North China Plain ◽

North China ◽

Nitrous Oxide Emissions ◽

Anthropogenic Source ◽

N2o Emissions ◽

Wheat Field ◽

The North ◽

The North China Plain ◽

N2o Fluxes

Abstract. Agricultural soil with fertilization is a main anthropogenic source for atmospheric nitrous oxide (N2O). N2O fluxes from a maize–wheat rotation field in the North China Plain (NCP) were investigated for 4 successive years using the static chamber method. The annual N2O fluxes from the control (without fertilization) and fertilization plots were 1.5 ± 0.2 and 9.4 ± 1.7 kg N ha−1 yr−1 in 2008–2009, 2.0 ± 0.01 and 4.0 ± 0.03 kg N ha−1 yr−1 in 2009–2010, 1.3 ± 0.02 and 5.0 ± 0.3 kg N ha−1 yr−1 in 2010–2011, and 2.7 ± 0.6 and 12.5 ± 0.1 kg N ha−1 yr−1 in 2011–2012, respectively. Annual direct emission factors (EFd's) in the corresponding years were 2.4 ± 0.5%, 0.60 ± 0.01%, 1.1 ± 0.09% and 2.9 ± 0.2%, respectively. Significant linear correlation between fertilized-induced N2O emissions (Y, kg N ha−1) during the periods of 10 days after fertilization and rainfall intensities from 4 days before to 10 days after fertilization (X, mm) in the 4 years was found as Y = 0.048X − 1.1 (N = 4, R2 = 0.99, P < 0.05). Therefore, the remarkable interannual variations of N2O emissions and the EFd's were mainly ascribed to the rainfall.

Download Full-text

Supplementary material to "Permafrost Nitrous Oxide Emissions Observed on a Landscape Scale Using Airborne Eddy Covariance Method"

10.5194/acp-2018-1108-supplement ◽

2018 ◽

Author(s):

Jordan Wilkerson ◽

Ronald Dobosy ◽

David S. Sayres ◽

Claire Healy ◽

Edward Dumas ◽

...

Keyword(s):

Nitrous Oxide ◽

Eddy Covariance ◽

Landscape Scale ◽

Nitrous Oxide Emissions ◽

Eddy Covariance Method ◽

Supplementary Material

Download Full-text

Nitrous oxide emissions from a beech forest floor measured by eddy covariance and soil enclosure techniques

Biogeosciences Discussions ◽

10.5194/bgd-2-581-2005 ◽

2005 ◽

Vol 2 (3) ◽

pp. 581-607

Author(s):

M. Pihlatie ◽

J. Rinne ◽

P. Ambus ◽

K. Pilegaard ◽

J. R. Dorsey ◽

...

Keyword(s):

Nitrous Oxide ◽

Spatial Variability ◽

Eddy Covariance ◽

Hot Spot ◽

Beech Forest ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

The Mean ◽

N2o Fluxes ◽

Trunk Space

Abstract. Spring time soil nitrous oxide (N2O) fluxes were measured in an old beech (Fagus sylvatica L.) forest with eddy covariance (EC) and chamber techniques. The aim was to compare the two techniques and to test whether EC can be used in the trunk-space of the forest to measure N2O. Mean N2O fluxes over the five week measurement period were 5, 10 and 16 μg N m-2h-1 from EC, automatic chamber and manual chambers, respectively. When data from one hot spot chamber was excluded the mean N2O flux of 8 μg N m-2h-1 from the soil chambers nearly equaled to the mean flux of 7 μg N m-2h-1 measured with EC from the direction were soil chambers located. Spatial variability in the N2O emissions was high in soil chamber measurements, while the EC integrated over this spatial variability and suggested that N2O emissions were uniform within the footprint area. The highest emissions measured with the EC occurred during the first week of May when the trees were leafing and when soil moisture content was at its highest. To our knowledge, this is the first study to demonstrate that the EC technique can be used to measure N2O fluxes in the trunk-space of a forest. If chamber techniques are used to estimate ecosystem level N2O emissions from forest soils, placing of the chambers should be considered carefully to cover the heterogeneity in the soil N2O emissions.

Download Full-text

Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark

Biogeosciences ◽

10.5194/bg-9-2989-2012 ◽

2012 ◽

Vol 9 (8) ◽

pp. 2989-3002 ◽

Cited By ~ 18

Author(s):

K. Schelde ◽

P. Cellier ◽

T. Bertolini ◽

T. Dalgaard ◽

T. Weidinger ◽

...

Keyword(s):

Land Use ◽

Nitrous Oxide ◽

Agricultural Land ◽

Nitrous Oxide Emissions ◽

Soil Conditions ◽

Spatial And Temporal Variability ◽

N2o Emissions ◽

N2o Production ◽

Mixed Farming ◽

N2o Fluxes

Abstract. Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were made over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during spring 2009 were relatively low, with maximum values below 20 ng N m−2 s−1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil conditions due to the absence of rain during the four previous weeks. Cumulative annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha−1 yr−1 and 5.5 kg N2O-N ha−1 yr−1) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application. Our findings confirm the importance of weather conditions as well as nitrogen management on N2O fluxes.

Download Full-text

Measurements of nitrogen oxides and ozone fluxes by eddy covariance at a meadow: evidence for an internal leaf resistance to NO<sub>2</sub>

Biogeosciences ◽

10.5194/bg-10-5997-2013 ◽

2013 ◽

Vol 10 (9) ◽

pp. 5997-6017 ◽

Cited By ~ 17

Author(s):

P. Stella ◽

M. Kortner ◽

C. Ammann ◽

T. Foken ◽

F. X. Meixner ◽

...

Keyword(s):

Eddy Covariance ◽

A Priori ◽

Terrestrial Ecosystems ◽

Stomatal Resistance ◽

Internal Resistance ◽

Ozone Production ◽

Deposition Flux ◽

Eddy Covariance Method ◽

Large Variability ◽

Leaf Resistance

Abstract. Nitrogen dioxide (NO2) plays an important role in atmospheric pollution, in particular for tropospheric ozone production. However, the removal processes involved in NO2 deposition to terrestrial ecosystems are still the subject of ongoing discussion. This study reports NO2 flux measurements made over a meadow using the eddy covariance method. The measured NO2 deposition fluxes during daytime were about a factor of two lower than a priori calculated fluxes using the Surfatm model without taking into account an internal (also called mesophyllic or sub-stomatal) resistance. Neither an underestimation of the measured NO2 deposition flux due to chemical divergence or an in-canopy NO2 source nor an underestimation of the resistances used to model the NO2 deposition explained the large difference between measured and modelled NO2 fluxes. Thus, only the existence of the internal resistance could account for this large discrepancy between model and measurements. The median internal resistance was estimated to be 300 s m−1 during daytime, but exhibited a large variability (100–800 s m−1). In comparison, the stomatal resistance was only around 100 s m−1 during daytime. Hence, the internal resistance accounted for 50–90% of the total leaf resistance to NO2. This study presents the first clear evidence and quantification of the internal resistance using the eddy covariance method; i.e. plant functioning was not affected by changes of microclimatological (turbulent) conditions that typically occur when using enclosure methods.

Download Full-text