Ammonia flux measurements above a corn canopy using relaxed eddy accumulation and a flux gradient system

2019 ◽  
Vol 264 ◽  
pp. 104-113 ◽  
Author(s):  
Andrew J. Nelson ◽  
Nebila Lichiheb ◽  
Sotiria Koloutsou-Vakakis ◽  
Mark J. Rood ◽  
Mark Heuer ◽  
...  
Keyword(s):  
Gradient System ◽  
Flux Gradient ◽  
Relaxed Eddy Accumulation ◽  
Flux Measurements ◽  
Ammonia Flux ◽  
Corn Canopy

scholarly journals Season-long ammonia flux measurements above fertilized corn in central Illinois, USA, using relaxed eddy accumulation

2017 ◽  
Vol 239 ◽  
pp. 202-212 ◽  
Author(s):  
Andrew J. Nelson ◽  
Sotiria Koloutsou-Vakakis ◽  
Mark J. Rood ◽  
LaToya Myles ◽  
Christopher Lehmann ◽  
...  
Keyword(s):  
Relaxed Eddy Accumulation ◽  
Flux Measurements ◽  
Central Illinois ◽  
Ammonia Flux

scholarly journals Ecosystem fluxes of hydrogen: a comparison of flux-gradient methods

2014 ◽  
Vol 7 (9) ◽  
pp. 2787-2805 ◽  
Author(s):  
L. K. Meredith ◽  
R. Commane ◽  
J. W. Munger ◽  
A. Dunn ◽  
J. Tang ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Forest Canopy ◽  
Trace Gases ◽  
Gradient Methods ◽  
Net Ecosystem Exchange ◽  
Heat Fluxes ◽  
Sensible Heat ◽  
Flux Gradient ◽  
Harvard Forest ◽  
Flux Measurements

Abstract. Our understanding of biosphere–atmosphere exchange has been considerably enhanced by eddy covariance measurements. However, there remain many trace gases, such as molecular hydrogen (H2), that lack suitable analytical methods to measure their fluxes by eddy covariance. In such cases, flux-gradient methods can be used to calculate ecosystem-scale fluxes from vertical concentration gradients. The budget of atmospheric H2 is poorly constrained by the limited available observations, and thus the ability to quantify and characterize the sources and sinks of H2 by flux-gradient methods in various ecosystems is important. We developed an approach to make nonintrusive, automated measurements of ecosystem-scale H2 fluxes both above and below the forest canopy at the Harvard Forest in Petersham, Massachusetts, for over a year. We used three flux-gradient methods to calculate the fluxes: two similarity methods that do not rely on a micrometeorological determination of the eddy diffusivity, K, based on (1) trace gases or (2) sensible heat, and one flux-gradient method that (3) parameterizes K. We quantitatively assessed the flux-gradient methods using CO2 and H2O by comparison to their simultaneous independent flux measurements via eddy covariance and soil chambers. All three flux-gradient methods performed well in certain locations, seasons, and times of day, and the best methods were trace gas similarity for above the canopy and K parameterization below it. Sensible heat similarity required several independent measurements, and the results were more variable, in part because those data were only available in the winter, when heat fluxes and temperature gradients were small and difficult to measure. Biases were often observed between flux-gradient methods and the independent flux measurements, and there was at least a 26% difference in nocturnal eddy-derived net ecosystem exchange (NEE) and chamber measurements. H2 fluxes calculated in a summer period agreed within their uncertainty and pointed to soil uptake as the main driver of H2 exchange at Harvard Forest, with H2 deposition velocities ranging from 0.04 to 0.10 cm s−1.

A Flux-Gradient System for Simultaneous Measurement of the CH4, CO2, and H2O Fluxes at a Lake–Air Interface

2014 ◽  
Vol 48 (24) ◽  
pp. 14490-14498 ◽  
Author(s):  
Wei Xiao ◽  
Shoudong Liu ◽  
Hanchao Li ◽  
Qitao Xiao ◽  
Wei Wang ◽  
...  
Keyword(s):  
Simultaneous Measurement ◽  
Gradient System ◽  
Flux Gradient ◽  
Air Interface

Accuracy of the relaxed eddy-accumulation technique, evaluated using CO2 flux measurements

1993 ◽  
Vol 66 (4) ◽  
pp. 341-355 ◽  
Author(s):  
E. Pattey ◽  
R. L. Desjardins ◽  
P. Rochette
Keyword(s):  
Co2 Flux ◽  
Relaxed Eddy Accumulation ◽  
Flux Measurements

scholarly journals A Relaxed Eddy Accumulation (REA) LOPAP-System for Flux Measurements of Nitrous Acid (HONO)

2021 ◽  
Author(s):  
Lisa von der Heyden ◽  
Walter Wißdorf ◽  
Ralf Kurtenbach ◽  
Jörg Kleffmann
Keyword(s):  
Nitrous Acid ◽  
Formation Mechanisms ◽  
Minor Importance ◽  
Night Time ◽  
Field Campaign ◽  
Air Masses ◽  
Relaxed Eddy Accumulation ◽  
Photolysis Frequency ◽  
Ultrasonic Anemometer ◽  
Flux Measurements

Abstract. In the present study a Relaxed Eddy Accumulation (REA) system for the quantification of vertical fluxes of nitrous acid (HONO) was developed and tested. The system is based on a three-channel-LOPAP instrument, for which two channels are used for the updrafts and downdrafts, respectively, and a third one for the correction of chemical interferences. The instrument is coupled to a REA gas inlet, for which an ultrasonic anemometer controls two fast magnetic valves to probe the two channels of the LOPAP instrument depending on the vertical wind direction. A software (PyREA) was developed, which controls the valves and measurement cycles, which regularly alternates between REA-, zero- and parallel ambient measurements. In addition, the assignment of the updrafts and downdrafts to the physical LOPAP channels is periodically alternated, to correct for differences in the interferences of the different air masses. During the study, only small differences of the interferences were identified for the updrafts and downdrafts excluding significant errors when using only one interference channel. In laboratory experiments, high precision of the two channels and the independence of the dilution corrected HONO concentrations on the length of the valve switching periods were demonstrated. A field campaign was performed in order to test the new REA-LOPAP system at the TROPOS monitoring station in Melpitz, Germany. HONO fluxes in the range of −4·1013 molecules m−2 s−1 (deposition) to +1.0·1014 molecules m−2 s−1 (emission) were obtained. A typical diurnal variation of the HONO fluxes was observed with low, partly negative fluxes during night-time and higher positive fluxes around noon. After an intensive rain period the positive HONO emissions during daytime were continuously increasing, which was explained by the drying of the upper most ground surfaces. Similar to other campaigns, the highest correlation of the HONO flux was observed with the product of the NO2 photolysis frequency and the NO2 concentration (J(NO2)·[NO2]), which implies a HONO formation by photosensitized conversion of NO2 on organic surfaces, like e.g. humic acids. Other postulated HONO formation mechanisms are also discussed, but are ranked being of minor importance for the present field campaign.

scholarly journals Ecosystem fluxes of hydrogen: a comparison of flux-gradient methods

2014 ◽  
Vol 7 (3) ◽  
pp. 2879-2928 ◽  
Author(s):  
L. K. Meredith ◽  
R. Commane ◽  
J. W. Munger ◽  
A. Dunn ◽  
J. Tang ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Forest Canopy ◽  
Trace Gases ◽  
Gradient Methods ◽  
Net Ecosystem Exchange ◽  
Heat Fluxes ◽  
Sensible Heat ◽  
Flux Gradient ◽  
Harvard Forest ◽  
Flux Measurements

Abstract. Our understanding of biosphere-atmosphere exchange has been considerably enhanced by eddy-covariance measurements, however there remain many trace gases, such as molecular hydrogen (H2), for which there are no suitable analytical methods to measure their fluxes by eddy covariance. In such cases, flux-gradient methods can be used to calculate ecosystem-scale fluxes from vertical concentration gradients. The budget of atmospheric H2 is poorly constrained by the limited available observations, thus the ability to quantify and characterize the sources and sinks of H2 by flux-gradient methods in various ecosystems is important. We developed an approach to make nonintrusive, automated measurements of ecosystem-scale H2 fluxes both above and below the forest canopy at the Harvard Forest in Petersham, MA for over a year. We used three flux-gradient methods to calculate the fluxes: two similarity methods that do not rely on a micrometeorological determination of the eddy diffusivity, K, based on (1) trace gases or (2) sensible heat and one flux-gradient method that (3) parameterizes K. We quantitatively assessed the flux-gradient methods on CO2 and H2O by comparison to their simultaneous independent flux measurements via eddy covariance and chambers. All three flux-gradient methods performed well in certain locations, seasons, and times of day, and the best methods were trace gas similarity above and K parameterization below the canopy. Sensible heat similarity required several independent measurements and the results were more variable, in part because those data were only available in the winter when heat fluxes and temperature gradients were small and difficult to measure. Biases were often observed between flux-gradient methods and the independent flux measurements, including at least a 26% difference in nocturnal eddy-derived Net Ecosystem Exchange (NEE) and soil chamber measurements. All flux-gradient methods used to calculate above and below canopy H2 fluxes pointed to soil uptake as the main driver of H2 exchange at Harvard Forest. H2 fluxes calculated in a summer period agreed within their uncertainty and indicated that H2 deposition velocities ranged from 0.04 to 0.1 cm s−1.

scholarly journals Effect of a New Manure Amendment on Ammonia Emissions from Poultry Litter

Atmosphere ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 257
Author(s):  
Kelsey Anderson ◽  
Philip A. Moore ◽  
Jerry Martin ◽  
Amanda J. Ashworth
Keyword(s):  
Aluminum Sulfate ◽  
Management Practice ◽  
Block Design ◽  
Poultry Litter ◽  
Poultry Production ◽  
Ammonia Emissions ◽  
Best Management ◽  
Randomized Block Design ◽  
Flux Measurements ◽  
Ammonia Flux

Treating manure with aluminum sulfate (alum) is a best management practice (BMP) which reduces ammonia (NH3) emissions and phosphorus (P) runoff from poultry litter. However, the price of alum has increased markedly in recent years, creating a need for less expensive products to control NH3 volatilization. The objective of this study was to evaluate the effects of a new litter amendment made from alum mud, bauxite, and sulfuric acid (alum mud litter amendment or AMLA) on NH3 emissions, litter chemistry, and poultry production in a pen trial. Three separate flocks of 1000 broilers were used for this study. The first flock of birds was used to produce the poultry litter needed for the experiment. The second and third flocks of birds were allocated to 20 pens in a randomized block design with four replicates of five treatments: (1) control, (2) 49 kg AMLA/100 m2 incorporated, (3) 98 kg AMLA/100 m2 incorporated, (4) 98 kg AMLA/100 m2 surface applied, and (5) 98 kg alum/100 m2 incorporated. Ammonia flux measurements and litter samples were collected from each pen at day 0, 7, 14, 21, 28, 35, and 42. The average litter pH for both flocks was higher in untreated litter (7.92) compared to incorporating alum (7.32) or AMLA (7.18). The two flocks’ average NH4-N concentrations at day 42 were 38% and 30% higher for the high rates of incorporated alum and AMLA compared to the untreated litter. Compared with untreated litter, AMLA reduced overall NH3 emissions by 27% to 52% which was not significantly different from reductions in emissions by alum (35%). Alum mud litter amendment reduced cumulative NH3 losses from litter as much as, and in some cases more than, alum applied at the same rate. These data indicate that AMLA, which can be manufactured for lower price than alum, is an effective alternative litter amendment for reducing NH3 emissions from poultry litter.

scholarly journals Areal-averaged trace gas emission rates from long-range open-path measurements in stable boundary layer conditions

2012 ◽  
Vol 5 (1) ◽  
pp. 1459-1496 ◽  
Author(s):  
K. Schäfer ◽  
R. H. Grant ◽  
S. Emeis ◽  
A. Raabe ◽  
C. von der Heide ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Land Surface ◽  
Stable Boundary Layer ◽  
Gradient Methods ◽  
Trace Gas ◽  
Emission Rates ◽  
Stable Boundary ◽  
Flux Gradient ◽  
Surface Emission ◽  
Flux Measurements

Abstract. Measurements of land-surface emission rates of greenhouse and other gases at large spatial scales (10 000 m2) are needed to assess the spatial distribution of emissions. This can be more readily done using spatial-integrating micro-meteorological methods than the widely-utilized small chamber measurements. Several micro-meteorological flux-gradient methods utilizing a non-intrusive path-averaging measurement method were evaluated for determining land-surface emission rates of trace gases under stable boundary layers. Successful application of a flux-gradient method requires confidence in the gradients of trace gas concentration and wind and in the applicability of boundary-layer turbulence theory. While there is relatively high confidence in flux measurements made under unstable atmospheres with mean winds greater than 1 m s−1, there is greater uncertainty in flux measurements made under free convective or stable conditions. The study involved quality-assured determinations of fluxes under low wind, stable or night-time atmospheric conditions when the continuous "steady-state" turbulence of the surface boundary layer breaks down and the layer has intermittent turbulence. Results indicate that the Monin-Obukhov similarity theory (MOST) flux-gradient methods that assume a log-linear profile of the wind speed and concentration gradient incorrectly determine vertical profiles and thus fluxes in the stable boundary layer.

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