The author is grateful to Dr. Marco Roelcke, Dr. Dirk Niekisch, Dr. Robert Quakernack, Dr. Kang Ni for their effort in developing and further development of this approach. Many thanks also to the field technicians Doris Ziermann and Jun Yang. The underlying investigations were supported by Deutsche Forschungsgemeinschaft, the Federal State Schleswig Holstein, EFRE grants of the European Union and SKW Piesteritz corp. as indicated in detail in the cited publications.

<ol>
	<li>Erisman, J. W., Bleeker, A., Hensen, A., Vermeulen, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Agricultural+air+quality+in+Europe+and+the+future+perspectives.">Agricultural air quality in Europe and the future perspectives.</a> Atmos. Environ. 42, 3209-3217 (2008).</li><li>Bremner, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+research+on+problems+in+the+use+of+urea+as+a+nitrogen+fertilizer.">Recent research on problems in the use of urea as a nitrogen fertilizer.</a> Fert. Res. 42, 321-329 (1995).</li><li>Sutton, M. A., Oenema, O., Erisman, J. W., Leip, A., van Grinsven, H., Winiwarter, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Too+much+of+a+good+thing.">Too much of a good thing.</a> Nature. 472, 159-161 (2011).</li><li>Glibert, P. M., Harrison, J., Heil, C., Seitzinger, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Escalating+worldwide+use+of+urea+-+a+global+change+contributing+to+coastal+eutrophication.">Escalating worldwide use of urea - a global change contributing to coastal eutrophication.</a> Biogeochemistry. 77, 441-463 (2006).</li><li>Sommer, S. G., Schjoerring, J. K., Denmead, O. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+emission+from+mineral+fertilizers+and+fertilized+crops.">Ammonia emission from mineral fertilizers and fertilized crops.</a> Adv. Agron. 82, 557-622 (2004).</li><li>Jensen, L. S., et al., Sutton, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Benefits+of+nitrogen+for+food,+fibre+and+industrial+production.">Benefits of nitrogen for food, fibre and industrial production.</a> The European Nitrogen Assessment. , (2011).</li><li>Sommer, S. G., Hutchings, N. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+emission+from+field+applied+manure+and+its+reduction+-+invited+paper.">Ammonia emission from field applied manure and its reduction - invited paper.</a> Eur. J. Agron. 15, 1-15 (2001).</li><li>Shah, S. B., Westerman, P. W., Arogo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+ammonia+concentrations+and+emissions+from+agricultural+land+and+liquid+surfaces:+A+review.">Measuring ammonia concentrations and emissions from agricultural land and liquid surfaces: A review.</a> J. Air Waste Manage. 56, 945-960 (2006).</li><li>Loubet, B., Cellier, P., Flura, D., Genermont, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+evaluation+of+the+wind-tunnel+technique+for+estimating+ammonia+volatilization+from+land:+Part+1.+Analysis+and+improvement+of+accuracy.">An evaluation of the wind-tunnel technique for estimating ammonia volatilization from land: Part 1. Analysis and improvement of accuracy.</a> J. Agr. Eng. Res. 72, 71-81 (1999).</li><li>Vandr&#233;, R., Kaupenjohann, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+Situ+Measurements+of+Ammonia+Emissions+from+Organic+Fertilizers+in+Plot+Experiments.">In Situ Measurements of Ammonia Emissions from Organic Fertilizers in Plot Experiments.</a> Soil Sci. Soc. Am. J. 62, 467-473 (1998).</li><li>Roelcke, M., Li, S. X., Tian, X. H., Gao, Y. J., Richter, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+comparisons+of+ammonia+volatilization+from+N+fertilizers+in+Chinese+loess+soils.">In situ comparisons of ammonia volatilization from N fertilizers in Chinese loess soils.</a> Nutr. Cycling Agroecosyst. 62 (1), 73-88 (2002).</li><li>Pacholski, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calibration+of+a+simple+method+for+determining+ammonia+volatilization+in+the+field+-+comparative+measurements+in+Henan+Province,+China.">Calibration of a simple method for determining ammonia volatilization in the field - comparative measurements in Henan Province, China.</a> Nutr. Cycling Agroecosyst. 74, 259-273 (2006).</li><li>Flesch, T. K., Harper, L. A., Powell, J. M., Wilson, J. 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ASABE. 52, 253-265 (2009).</li><li>Gericke, D., Pacholski, A., Kage, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+ammonia+emissions+in+multi-plot+field+experiments.">Measurement of ammonia emissions in multi-plot field experiments.</a> Biosystems Eng. 108 (2), 164-173 (2011).</li><li>Quakernack, R., Pacholski, A., Techow, A., Herrmann, A., Taube, F., Kage, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+volatilization+and+yield+response+after+application+of+biogas+residues+to+energy+crops+in+a+coastal+marsh+of+Northern+Germany.">Ammonia volatilization and yield response after application of biogas residues to energy crops in a coastal marsh of Northern Germany.</a> Agric., Ecosyst. Environ. 160, 66-74 (2012).</li><li>Ni, K., Pacholski, A., Gericke, D., Kage, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+duration+required+for+determining+total+ammonia+losses+after+field+application+of+slurries+by+trail+hoses.">Measurement duration required for determining total ammonia losses after field application of slurries by trail hoses.</a> J. Agr. Sci. 151 (1), 34-43 (2013).</li><li>von Bobrutzki, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Field+inter-comparison+of+eleven+atmospheric+ammonia+measurement+techniques.">Field inter-comparison of eleven atmospheric ammonia measurement techniques.</a> Atmos. Meas. Tech. 3, 91-112 (2010).</li><li>Ni, K., Pacholski, A., Kage, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ammonia+volatilization+after+application+of+urea+to+winter+wheat+over+3+years+affected+by+novel+urease+and+nitrification+inhibitors.">Ammonia volatilization after application of urea to winter wheat over 3 years affected by novel urease and nitrification inhibitors.</a> Agric. Ecosyst. Environ. 197, 184-194 (2014).</li><li>Sintermann, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Are+ammonia+emissions+from+field-applied+slurry+substantially+over-estimated+in+European+emission+inventories.">Are ammonia emissions from field-applied slurry substantially over-estimated in European emission inventories.</a> Biogeosciences. 9, 1611-1632 (2012).</li><li>Mannheim, T., Braschkat, J., Marschner, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+ammonia+emission+after+liquid+manure+application.+2.+Comparison+of+the+wind+tunnel+and+the+IHF+method+under+field+conditions.">Measurement of ammonia emission after liquid manure application. 2. Comparison of the wind tunnel and the IHF method under field conditions.</a> J. Plant Nutr. Soil Sci. 158, 215-219 (1995).</li><li>Puchalski, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Passive+ammonia+monitoring+in+the+United+States:+Comparing+three+different+sampling+devices.">Passive ammonia monitoring in the United States: Comparing three different sampling devices.</a> Environ. Monit. 13 (11), 3156-3167 (2011).</li><li>Tang, Y. S., Cape, J. N., Sutton, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+and+types+of+passive+samplers+for+monitoring+atmospheric+NO2+and+NH3+concentrations.">Development and types of passive samplers for monitoring atmospheric NO2 and NH3 concentrations.</a> ScientificWorldJournal. 1, 513-529 (2001).</li></ol>

The author declares that he has no competing financial interests.

It was shown that the proposed method can be used to compare ammonia emissions from different fertilizer treatments in replicated field trials and to use the obtained statistically significant information from these measurements to improve management of N fertilizers. The quantity of emissions obtained by this approach has been validated in earlier studies by comparison with micrometeorological measurements13,15,16. In this paper, the quantitative validity of this approach was indirectly demonstrated by a clos...

Ammonia (NH3) is the only atmospheric trace gas predominantly (90%) emitted from agricultural sources in the EU. Although agriculture is also a major source (&#62;50% of EU emissions), these contribute only to about ~5% to the total of EU15 anthropogenic greenhouse gas emissions. In contrast, agricultural NH3 emissions are responsible for about 45% of emission-derived eutrophication, 31% of acidification and 12% fine dust formation within the EU151. In addition to detrimental effects to ecosystems and human health, nitrogen (N) loss by NH3 emission is an economic loss to farmers2. Nitrogen fertilizer is essential for the high rate of food production delivered by modern agriculture. Apart of the environmental damage, NH3 emissions thus, mean a considerable loss of nutrients, as NH3 is derived from fertilizer ammonium, in addition to nitrate the key mineral nitrogen species directly available to the plant governing crop growth processes and yield. Application of N fertilizers contributes &#8364;20-80 billion of profit per year for EU farmers but in turn it was estimated that NH3 released into the air from agriculture causes ~&#8364;50 billion in annual damage in the EU3. Therefore, reduction of NH3 emissions is essential for both decreasing the environmental effects and increasing the efficiency of the applied N.
In agriculture, NH3 is mainly emitted from animal houses, manure (slurries, anaerobic digestates (AD), solid manure) storage and management as well as manure field application. The propensity to emit NH3 differs depending on manure composition, e.g. dry matter content and manure pH. To some extent ammonium and amine based synthetic nitrogen fertilizers as urea and diammonium phosphate also contribute to NH3 emissions. Although calcareous ammonium nitrate (CAN) is the principal N fertilizer in many European countries, the use of granular urea has increased, and was second to CAN in Central and Western Europe in 20124. Urea is particularly popular in developing countries due to its advantages of a high N content, safety, and easy transportation and is the world&#39;s most important synthetic nitrogen fertilizer5. However, the increase of pH and surface soil NH4+-concentrations resulting from urea hydrolysis can result in high NH3 emissions. This can cause low N use efficiency, especially in alkaline soil or soil with low sorption capacity, which limits the use of urea fertilizer in Europe6,7.
Many studies on NH3 emission from organic and mineral fertilizer application and livestock housing have been performed in recent decades6, 8. Nevertheless, the research related to NH3 emissions after application of ammonia emitting fertilizers is still limited. This in particular applies to the relationship between ammonia emissions, fertilizer type used, site conditions and crop growth. Under ideal conditions this requires replicated field trials due to the variable response of crops to treatments which can only be validated in an experimental design including field replication for statistical testing.
Ammonia losses should therefore also be determined in replicated multi-plot field trials9, but the dominating ammonia loss methods yielding quantitative emissions (i.e. kg N/(ha*h)) require large field areas (micrometeorological methods), expensive equipment (wind tunnels) or in-field electrical power supply which make their application in replicated field trials difficult or impossible. In addition, specific settings of wind tunnels have been criticized with respect to the accuracy of obtained emission values10. Therefore, there is a strong need for an ammonia loss method to determine ammonia emissions in replicated field trials. This method could be used to help improve agricultural measures to reduce ammonia emissions based on statistically validated effects of site conditions, fertilizer type, application methods and crop development.
The basic idea of the new methodology, calibrated passive sampling, is to link a simple semi-quantitative measuring method for the measurement on many plots, with a quantitative method by simultaneous measurements with both methods on a few plots. Passive samplers modified compared to the design in the original publication11 are used as a semi-quantitative measurement method. The Dynamic-Tube Method (DTM)12, a calibrated dynamic chamber method, is employed to obtain a transfer coefficient, which converts the semi-quantitative losses of the passive sampler to quantitative losses (kg N ha-1). Due to the low air exchange rate in the chamber system uncalibrated emissions obtained from the DTM are about one order of magnitude lower than true emissions. However, this problem was overcome by a calibration equation which corrects the chamber fluxes depending on in-situ wind conditions13. These calibration equations can only be applied when chambers have the same internal headspace volume and design as those used in the calibration trials. Chambers can be directly inserted in soil or placed on soil rings. The latter prevent excessive disturbance of the soil and allows an almost airtight introduction of the chambers on dense grass swards or compacted soil. Moreover, the exact amount of fertilizer to be tested can be applied inside the soil rings. However, soil clods on the soil rings can also entail clamping between the chamber and the soil ring.
<img alt="Figure 1" src="/files/ftp_upload/53273/53273fig1.jpg" /> 
Figure 1: Simultaneous measurement with passive samplers and chamber method (DTM) in field plot. Passive sampler is located in the center of a square plot 0.15 m above soil/canopy. Measurements with DTM are made at least 2 locations within a plot per measurement date. Areas dedicated for harvest should not be affected by chamber and passive sampler measurement operations.
To derive the transfer coefficients measurements are carried out simultaneously on a small number of plots with both methods (Figure 1). It is important that they are applied with the same total measurement duration and that measurements are carried out at the same time (within 1 hr). The principle facilitating the application of a transfer coefficient for many plots is based on the fact that passive samplers placed in a homogeneous experimental field, with appropriate distance to obstacles disturbing the wind field as hedges, buildings etc. (at least 10 times, ideally 20 times of obstacle height)14, have the same NH3 absorption behavior under identical environmental conditions. So, for example, 50% lower emission on a plot would directly translate to 50% reduced ammonia uptake by a sampler solution. Therefore, a transfer coefficient used for scaling of acid trap values on a single plot can be used to scale the values of all acid traps used in the same field trial. Due to effects of varying environmental conditions (temperature, wind speed, surface roughness) on ammonia uptake efficiency of passive samplers11 the transfer coefficient has to be derived for each measurement campaign, respectively.
The general features of the two methods applied and the required design of field trials include 4 dynamic chambers placed onto the soil connected with Polytetrafluoroethylene (PTFE) tubing and ventilated by a bellows pump (DTM), passive samplers and large quadratic experimental plots with large buffer spaces for reducing the effect of NH3 drift between plots on the emission measurement on the actual plot.
The passive samplers are filled with dilute sulfuric acid (0.05 M H2SO4) and are placed in the center of the plots. The solution in the passive samplers continuously absorbs ammonia, and is replaced regularly depending on the expected intensity of the emissions. Simultaneously, NH3 fluxes are measured with the DTM on two treatment plots and a control plot at specific points in time. In contrast to wind tunnels, both methods combined in calibrated passive sampling have only very limited effects on soil moisture, soil temperature and rainfall which can affect ammonia emission losses very strongly6,8. While passive samplers are mounted 0.15 m above soil and canopy surface, without any effect on those variables, measurements with DTM chambers last only for about 5 min reducing potential chamber effects to a minimum.
Accurate results for NH4+ concentrations in the sampling solution can be obtained by measurements with ammonium-sensitive electrodes. Measurements with Continuous-Flow Auto Analyzers can be problematic as pH sensitive color reaction applied in these instruments can by hampered by the acidic pH of the sampling solution and chemicals used require modification. NH3 concentrations in the air passed through the chamber system of the DTM are instantaneously measured with indicator tubes. The measured NH3 concentrations are recorded on a data sheet after each measurement.
For DTM, NH3 fluxes (mg N/(m&#178; *h)) are calculated from measured NH3 concentrations and air flow rate through the 4 chamber system and the area covered by the chambers (Eq. 1, paragraph 2.5.1). The resulting un-calibrated fluxes (which underestimate the true emissions) are scaled to quantitative losses with a calibration equation (Eq. 2 and 3, see paragraph 2.5.1). Scaled cumulative NH3 losses (kg N/ha) of the DTM are calculated by averaging the fluxes between two subsequent measurement dates, multiplying this average flux with the duration of each interval, and adding-up all losses from all measurement intervals of a measurement campaign. Cumulative qualitative NH3 losses (ppm sum) from passive samplers are calculated by adding up collected NH4+-concentrations (ppm) on a plot within an experimental campaign. This is feasible because under identical volume and measurement temperatures, ppm values directly translate into captured amounts of ammonia. To scale these qualitative losses to quantitative losses the transfer coefficient (kg N/(ha *ppm)) is derived by relating cumulative final loss of the DTM (kg N ha-1) to the total sum of concentrations in the samplers measured on the same plots. This transfer coefficient is then used to convert semi-quantitative emissions from passive sampling to quantitative fluxes (e.g. kg N/ha) by multiplying the cumulative concentrations with the transfer coefficient.
Loss of water from the collectors through evaporation does not affect the absorption capacity but has to be corrected later for data analysis. Spilling of solution due to during strong winds has not been observed even in the coastal marshes of northern Germany. Decisive for a successful application of this approach is the identical design of all passive samplers applied in the field including identical position and height of placement within a plot. Several designs of passive samplers have been successfully applied in the past. This paper suggests one particular design which has proved reliable and easy to operate in field measurements. The presented approach has been extensively tested by comparison to standard ammonia loss methods (micrometeorological methods) in about 15 field trials confirming the quantitative validity of the procedure15,16 and an unbiased representation of the emissions dynamics17. The coefficient of determination (r&#178;) of calibrated fluxes compared to the micrometeorological measurements in the calibration study13 was 0.84, quite similar to the coefficient obtained by comparing ammonia sensors for measured atmospheric ammonia concentrations in a recent study18. The relative root-mean-square error of cumulative ammonia losses was 17%, also quite close to values obtained in other studies comparing micrometeorological measurements13. In the second validation where the proposed method was compared to micrometeorological measurements of ammonia emissions from organic slurries (5 separate trials), an r&#178; of 0.96 (slope of curve &#8776; 1) and a relative root-mean-square error of 5% was obtained for final cumulated ammonia emissions15. The method has proved sensitive in a 3 year field trial using different synthetic N fertilizers19. The application of this approach is restricted to average wind speeds &#8804;4 m/sec at 2 m height as the chamber method was only validated under those conditions 13,15,16.
A measurement campaign is defined as an experiment testing ammonia emissions after application of fertilizers on several plots lasting for several days, up to weeks. Each measurement campaign on a plot consists of several subsequent sampling intervals (passive sampler) or measurement dates (DTM). Sampling interval is defined as sequential duration of absorbance of emitted ammonia by a sampling solution. Measurement date is defined as sequential point in time at which DTM measurements are done on different plots used for deriving the transfer coefficient.

<table><tbody><tr><td>stainless steel Dr&amp;auml;ger chamber + soil rings</td><td>Fa. Hofmann GmbH, Metallindustriewerk, Kiel, Germany</td><td>no number</td><td></td></tr><tr><td>roofs and stainless steel rod for passive sampler</td><td>Fa. Hofmann GmbH, Metallindustriewerk, Kiel, Germany</td><td>no number</td><td></td></tr><tr><td>ammonia electrode + bench</td><td>Thermo scientific</td><td>Cat. No. 9512BNWP or 951201</td><td></td></tr><tr><td>ammonia electrode filling solution</td><td>Thermo scientific</td><td>Cat. No. 951202</td><td></td></tr><tr><td>Ammonia calibration standards; 0.1&amp;nbsp;M ammonia chloride standard</td><td>Thermo scientific</td><td>Cat. No. 951006&amp;nbsp;</td><td></td></tr><tr><td>Dr&amp;auml;ger pumps</td><td>Draeger Safety AG&amp;amp; Co Kg</td><td></td><td></td></tr><tr><td>Dr&amp;auml;ger tubes</td><td>Draeger Safety AG&amp;amp; Co Kg</td><td>types: 0.25/a; 2/a; 5/a</td><td></td></tr><tr><td>acid resistant passive sampling bottles (Azlon bottle, HDPE)</td><td>Dunn Labortechnik GmbH</td><td>Cat.No.: BGE230P</td><td></td></tr><tr><td>small vials (scintillation bottles PE 60 mm x 27&amp;nbsp;mm)</td><td>any laboratory store</td><td></td><td></td></tr><tr><td>PTFE tubing 7 mm x 1&amp;nbsp;mm WDG</td><td>any laboratory store</td><td></td><td></td></tr><tr><td>connectors PP Y-Form 6-7 mm</td><td>any laboratory store</td><td></td><td></td></tr></tbody></table>

calibrated passive sampling - multi-plot field measurements of nh3 emissions with a combination of dynamic tube method and passive samplers

Agricultural ammonia (NH3) emissions (90% of total EU emissions) are responsible for about 45% airborne eutrophication, 31% soil acidification and 12% fine dust formation within the EU15. But NH3 emissions also mean a considerable loss of nutrients. Many studies on NH3 emission from organic and mineral fertilizer application have been performed in recent decades. Nevertheless, research related to NH3 emissions after application fertilizers is still limited in particular with respect to relationships to emissions, fertilizer type, site conditions and crop growth. Due to the variable response of crops to treatments, effects can only be validated in experimental designs including field replication for statistical testing. The dominating ammonia loss methods yielding quantitative emissions require large field areas, expensive equipment or current supply, which restricts their application in replicated field trials. This protocol describes a new methodology for the measurement of NH3 emissions on many plots linking a simple semi-quantitative measuring method used in all plots, with a quantitative method by simultaneous measurements using both methods on selected plots. As a semi-quantitative measurement method passive samplers are used. The second method is a dynamic chamber method (Dynamic Tube Method) to obtain a transfer quotient, which converts the semi-quantitative losses of the passive sampler to quantitative losses (kg nitrogen ha-1). The principle underlying this approach is that passive samplers placed in a homogeneous experimental field have the same NH3 absorption behavior under identical environmental conditions. Therefore, a transfer co-efficient obtained from single passive samplers can be used to scale the values of all passive samplers used in the same field trial. The method proved valid under a wide range of experimental conditions and is recommended to be used under conditions with bare soil or small canopies (&#60;0.3 m). Results obtained from experiments with taller plants should be treated more carefully.

In year 2014, a field trial was set up in the center of Denmark for testing the effects of several methods to reduce ammonia emissions after application of cattle slurry: incorporation with a rotary tiller, incorporation of acidified slurry and closed slot injection (injection of slurry in soil with subsequent coverage with soil). As a comparison with a high emission application technique and in particular for proper application of the chamber method trail hose application of slurry was also included. Altogether 24 plots were included in thi...

Watch this Scientific Journal Video about Calibrated Passive Sampling - Multi-plot Field Measurements of NH3 Emissions with a Combination of Dynamic Tube Method and Passive Samplers at JoVE.com

Calibrated Passive Sampling - Multi-plot Field Measurements of NH3 Emissions with a Combination of Dynamic Tube Method and Passive Samplers

Ammonia emissions are a major threat to the environment by eutrophication, soil acidification and fine particle formation and stem mainly from agricultural sources. This method allows ammonia loss measurements in replicated field trials enabling statistical analysis of emissions and of relationships between crop development and emissions.

Calibrated Passive Sampling - Multi-plot Field Measurements of NH3 Emissions with a Combination of Dynamic Tube Method and Passive Samplers

Agricultural ammonia (NH3) emissions (90% of total EU emissions) are responsible for about 45% airborne eutrophication, 31% soil acidification and 12% ...

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12.3K Views.  Leuphana University.  Ammoniakemissie zijn een grote bedreiging voor het milieu door vermesting, verzuring van de bodem en fijne deeltjesvorming en vloeien voornamelijk voort uit agrarische bronnen. Deze methode maakt het mogelijk ammoniak verlies metingen in gerepliceerd veldproeven op statistische analyse van de emissies en van de relaties tussen ontwikkeling en emissies gewas. 

Video: Calibrated Passive Sampling - Multi-plot Field Measurements of NH3 Emissions with a Combination of Dynamic Tube Method and Passive Samplers

Measurement of Greenhouse Gas Flux from Agricultural Soils Using Static Chambers

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the biogeochemical drivers of climate change and to the development and evaluation of GHG mitigation strategies based on modulation of landscape management practices. The static chamber-based method described here is based on trapping gases emitted from the soil surface within a chamber and collecting samples from the chamber headspace at regular intervals for analysis by gas chromatography. Change in gas concentration over time is used to calculate flux. This method can be utilized to measure landscape-based flux of carbon dioxide, nitrous oxide, and methane, and to estimate differences between treatments or explore system dynamics over seasons or years. Infrastructure requirements are modest, but a comprehensive experimental design is essential. This method is easily deployed in the field, conforms to established guidelines, and produces data suitable to large-scale GHG emissions studies.

This article showcases the static chamber-based method for measurement of greenhouse gas flux from soil systems. With relatively modest infrastructure investments, measurements may be obtained from multiple treatments/locations and over timeframes ranging from hours to years.

Measurement of greenhouse gas (GHG) fluxes between the soil and the atmosphere, in both managed and unmanaged ecosystems, is critical to understanding the ...

Quantitative Detection of Trace Explosive Vapors by Programmed Temperature Desorption Gas Chromatography-Electron Capture Detector

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive vapor samples. The direct liquid deposition method yields a higher fidelity between the analysis of vapor samples and the analysis of solution standards than using separate injection methods for vapors and solutions, i.e., samples collected on vapor collection tubes and standards prepared in solution vials. Additionally, the method can account for instrumentation losses, which makes it ideal for minimizing variability and quantitative trace chemical detection. Gas chromatography with an electron capture detector is an instrumentation configuration sensitive to nitro-energetics, such as TNT and RDX, due to their relatively high electron affinity. However, vapor quantitation of these compounds is difficult without viable vapor standards. Thus, we eliminate the requirement for vapor standards by combining the sensitivity of the instrumentation with a direct liquid deposition protocol to analyze trace explosive vapor samples.

Trace explosive vapors of TNT and RDX collected on sorbent-filled thermal desorption tubes were analyzed using a programmed temperature desorption system coupled to GC with an electron capture detector. The instrumental analysis is combined with direct liquid deposition method to reduce sample variability and account for instrumentation drift and losses.

The direct liquid deposition of solution standards onto sorbent-filled thermal desorption tubes is used for the quantitative analysis of trace explosive ...

Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx

Nitrogen oxides (NOx = NO + NO2) are a family of atmospheric trace gases that have great impact on the environment. NOx concentrations directly influence the oxidizing capacity of the atmosphere through interactions with ozone and hydroxyl radicals. The main sink of NOx is the formation and deposition of nitric acid, a component of acid rain and a bioavailable nutrient. NOx is emitted from a mixture of natural and anthropogenic sources, which vary in space and time. The collocation of multiple sources and the short lifetime of NOx make it challenging to quantitatively constrain the influence of different emission sources and their impacts on the environment. Nitrogen isotopes of NOx have been suggested to vary amongst different sources, representing a potentially powerful tool to understand the sources and transport of NOx. However, previous methods of collecting atmospheric NOx integrate over long (week to month) time spans and are not validated for the efficient collection of NOx in relevant, diverse field conditions. We report on a new, highly efficient field-based system that collects atmospheric NOx for isotope analysis at a time resolution between 30 min and 2 hr. This method collects gaseous NOx in solution as nitrate with 100% efficiency under a variety of conditions. Protocols are presented for collecting air in urban settings under both stationary and mobile conditions. We detail the advantages and limitations of the method and demonstrate its application in the field. Data from several deployments are shown to 1) evaluate field-based collection efficiency by comparisons with in situ NOx concentration measurements, 2) test the stability of stored solutions before processing, 3) quantify in situ reproducibility in a variety of urban settings, and 4) demonstrate the range of N isotopes of NOx detected in ambient urban air and on heavily traveled roadways.

Automated, High-resolution Mobile Collection System for the Nitrogen Isotopic Analysis of NOx

Previous work suggests that the nitrogen isotopic composition of atmospheric nitrogen oxides might distinguish the influence of different sources in the environment. We report on an automated, mobile, field-based method for the high collection efficiency of atmospheric NOx for N isotopic analysis at an hourly time resolution.

Nitrogen oxides (NOx = NO + NO2) are a family of atmospheric trace gases that have great impact on the environment. NOx concentrations directly influence ...

Production and Measurement of Organic Particulate Matter in a Flow Tube Reactor

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the production of synthetic PM for laboratory studies have become a widespread necessity. Herein, experimental protocols demonstrate approaches to produce aerosolized organic PM by &#945;-pinene ozonolysis in a flow tube reactor. Methods are described for measuring the size distributions and morphology of the aerosol particles. The video demonstrates basic operations of the flow tube reactor and related instrumentation. The first part of the video shows the procedure for preparing gas-phase reactants, ozonolysis, and production of organic PM. The second part of the video shows the procedures for determining the properties of the produced particle population. The particle number-diameter distributions show different stages of particle growth, namely condensation, coagulation, or a combination of both, depending on reaction conditions. The particle morphology is characterized by an aerosol particle mass analyzer (APM) and a scanning electron microscope (SEM). The results confirm the existence of non-spherical particles that have grown from coagulation for specific reaction conditions. The experimental results also indicate that the flow tube reactor can be used to study the physical and chemical properties of organic PM for relatively high concentrations and short time frames.

This paper describes the operation procedure for the flow tube reactor and related data collection. It shows the protocols for setting the experiments, recording data and generating the number-diameter distribution as well as the particle mass information, which gives useful information about chemical and physical properties of the organic aerosols.

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the ...

Assessment of Methane and Nitrous Oxide Fluxes from Paddy Field by Means of Static Closed Chambers Maintaining Plants Within Headspace

This protocol describes the measurement of greenhouse gas (GHG) emissions from paddy soils using the static closed chamber technique. This method is based on the diffusion theory. A known volume of air overlaying a defined soil area is enclosed within a parallelepiped cover (named &#34;chamber&#34;), for a defined period of time. During this enclosure period, gases (methane (CH4) and nitrous oxide (N2O)) move from soil pore air near their microbial source (i.e., methanogens, nitrifiers, denitrifiers) to the chamber headspace, following a natural concentration gradient. Fluxes are then estimated from chamber headspace concentration variations sampled at regular intervals throughout the enclosure and then analyzed with gas chromatography. Among the techniques available for GHG measurement, the static closed chamber method is suitable for plot experiments, as it does not require large homogenously treated soil areas. Furthermore, it is manageable with limited resources and can identify relationships among ecosystem properties, processes, and fluxes, especially when combined with GHG driving force measurements. Nevertheless, with respect to the micrometeorological method, it causes a minimal but still unavoidable soil disturbance, and allows a minor temporal resolution. Several phases are key to the method implementation: i) chamber design and deployment, ii) sample handling and analyses, and iii) flux estimation. Technique implementation success in paddy fields demands adjustments for field flooding during much of the cropping cycle, and for rice plant maintenance within the chamber headspace during measurements. Therefore, the additional elements to be considered with respect to the usual application of non-flooded agricultural soils consist of devices for: i) avoiding any unintended water disturbance that could overestimate fluxes, and ii) including rice plants within the chamber headspace to fully consider gases emitted through aerenchyma transportation.

The overall goal of this protocol is to measure greenhouse gas emissions from paddy fields using the static closed chamber technique. The measurement system needs specific adjustments due to the presence of both a permanent water layer in the field and of the plants within the chamber headspace.

This protocol describes the measurement of greenhouse gas (GHG) emissions from paddy soils using the static closed chamber technique. This method is based ...

Lab-Scale Model to Evaluate Odor and Gas Concentrations Emitted by Deep Bedded Pack Manure

A lab-scaled simulated bedded pack model was developed to study air quality and nutrient composition of deep-bedded packs used in cattle mono-slope facilities. This protocol has been used to effectively evaluate many different bedding materials, environmental variables (temperature, humidity), and potential mitigation treatments that can improve air quality in commercial deep-bedded mono-slope facilities. The model is dynamic and allows researchers to easily collect many chemical and physical measurements from the bedded pack. Weekly measurements, collected over the course of six to seven weeks, allows sufficient time to see changes in air quality measurements over time as the bedded pack matures. The data collected from the simulated bedded packs is within the range of concentrations previously measured in commercial deep-bedded mono-slope facilities. Past studies have demonstrated that 8 - 10 experimental units per treatment are sufficient to detect statistical differences among the simulated bedded packs. The bedded packs are easy to maintain, requiring less than 10 minutes of labor per bedded packs per week to add urine, feces, and bedding. Sample collection using the gas sampling system requires 20 - 30 minutes per bedded pack, depending on the measurements that are being collected. The use of lab-scaled bedded packs allows the researcher to control variables such as temperature, humidity, and bedding source that are difficult or impossible to control in a research or commercial facility. While not a perfect simulation of &#34;real-world&#34; conditions, the simulated bedded packs serve as a good model for researchers to use to examine treatment differences among bedded packs. Several lab-scale studies can be conducted to eliminate possible treatments before trying them in a research or commercial-sized facility.

A protocol has been developed to measure gases, odors, and nutrient composition in lab-scaled bedded manure packs, which can be used to study ways to improve air quality in commercial cattle facilities using deep-bedded manure packs.

A lab-scaled simulated bedded pack model was developed to study air quality and nutrient composition of deep-bedded packs used in cattle mono-slope ...

Design and Use of a Full Flow Sampling System (FFS) for the Quantification of Methane Emissions

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas industry faces continued scrutiny for methane emissions from across the supply chain, due to methane&#39;s relatively high global warming potential (25-84x that of carbon dioxide, according to the Energy Information Administration). Currently, a variety of techniques of varied uncertainties exists to measure or estimate methane emissions from components or facilities. Currently, only one commercial system is available for quantification of component level emissions and recent reports have highlighted its weaknesses.
In order to improve accuracy and increase measurement flexibility, we have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases based on transportation emissions measurement principles. The FFS is a modular system that consists of an explosive-proof blower(s), mass airflow sensor(s) (MAF), thermocouple, sample probe, constant volume sampling pump, laser based greenhouse gas sensor, data acquisition device, and analysis software. Dependent upon the blower and hose configuration employed, the current FFS is able to achieve a flow rate ranging from 40 to 1,500 standard cubic feet per minute (SCFM). Utilization of laser-based sensors mitigates interference from higher hydrocarbons (C2+). Co-measurement of water vapor allows for humidity correction. The system is portable, with multiple configurations for a variety of applications ranging from being carried by a person to being mounted in a hand drawn cart, on-road vehicle bed, or from the bed of utility terrain vehicles (UTVs). The FFS is able to quantify methane emission rates with a relative uncertainty of &#177; 4.4%. The FFS has proven, real world operation for the quantification of methane emissions occurring in conventional and remote facilities.

Design and Use of a Full Flow Sampling System FFS for the Quantification of Methane Emissions

We have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases from across the natural gas supply chain.

The use of natural gas continues to grow with increased discovery and production of unconventional shale resources. At the same time, the natural gas ...

Engineering

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O

The importance of understanding the fate of nitrate (NO3&#8722;), which is the dominant N species transferred from terrestrial to aquatic ecosystems, has been increasing because global nitrogen loads have dramatically increased following industrialization. Dissimilatory nitrate reduction to ammonium (DNRA) and denitrification are both microbial processes that use NO3&#8722; for respiration. Compared to denitrification, quantitative determinations of the DNRA activity have been carried out only to a limited extent. This has led to an insufficient understanding of the importance of DNRA in NO3&#8722; transformations and the regulating factors of this process. The objective of this paper is to provide a detailed procedure for the measurement of the potential DNRA rate in environmental samples. In brief, the potential DNRA rate can be calculated from the 15N-labeled ammonium (15NH4+) accumulation rate in 15NO3&#8722; added incubation. The determination of the 14NH4+ and 15NH4+ concentrations described in this paper is comprised of the following steps. First, the NH4+ in the sample is extracted and trapped on an acidified glass filter as ammonium salt. Second, the trapped ammonium is eluted and oxidized to NO3&#8722; via persulfate oxidation. Third, the NO3&#8722; is converted to N2O via an N2O reductase deficient denitrifier. Finally, the converted N2O is analyzed using a previously developed quadrupole gas chromatography&#8211;mass spectrometry system. We applied this method to salt marsh sediments and calculated their potential DNRA rates, demonstrating that the proposed procedures allow a simple and more rapid determination compared to previously described methods.

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O

A series of methods to determine the potential DNRA rate based on 14NH4+/15NH4+ analyses is provided in detail. NH4+ is converted into N2O via several steps and analyzed using quadrupole gas chromatography&#8211;mass spectrometry.

The importance of understanding the fate of nitrate (NO3&#8722;), which is the dominant N species transferred from terrestrial to aquatic ecosystems, has ...

A Practical and Low-Cost Setup to Measure Methane in Aqueous Samples

Measuring Dissolved Methane in Aquatic Ecosystems Using An Optical Spectroscopy Gas Analyzer

Measuring greenhouse gas (GHG) fluxes and pools in ecosystems are becoming increasingly common in ecological studies due to their relevance to climate change. With it, the need for analytical platforms adaptable to measuring different pools and fluxes within research groups also grows. This study aims to develop a procedure to use portable optical spectroscopy-based gas analyzers, originally designed and marketed for gas flux measurements, to measure GHG concentrations in aqueous samples. The protocol involves the traditional headspace equilibration technique followed by the injection of a headspace gas subsample into a chamber connected through a closed loop to the inlet and outlet ports of the gas analyzer. The chamber is fabricated from a generic mason jar and simple laboratory supplies, and it is an ideal solution for samples that may require pre-injection dilution. Methane concentrations measured with the chamber are tightly correlated (r2 &#62; 0.98) with concentrations determined separately through gas chromatography-flame ionization detection (GC-FID) on subsamples from the same vials. The procedure is particularly relevant for field studies in remote areas where chromatography equipment and supplies are not readily available, offering a practical, cheaper, and more efficient solution for measuring methane and other dissolved greenhouse gas concentrations in aquatic systems.

This study demonstrates an approach to measure methane gas concentrations in aqueous samples using portable optical analyzers coupled to an injection chamber in a closed loop. The results are similar to conventional gas chromatography, presenting a practical and low-cost alternative particularly suitable for remote field studies.

Measuring greenhouse gas (GHG) fluxes and pools in ecosystems are becoming increasingly common in ecological studies due to their relevance to climate ...

Fast and Accurate Exhaled Breath Ammonia Measurement

This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that uses a quantum cascade based laser. The monitor is coupled to a sampler that measures mouth pressure and carbon dioxide. The system is temperature controlled and specifically designed to address the reactivity of this compound. The sampler provides immediate feedback to the subject and the technician on the quality of the breath effort. Together with the quick response time of the monitor, this system is capable of accurately measuring exhaled breath ammonia representative of deep lung systemic levels. 
Because the system is easy to use and produces real time results, it has enabled experiments to identify factors that influence measurements. For example, mouth rinse and oral pH reproducibly and significantly affect results and therefore must be controlled. Temperature and mode of breathing are other examples. As our understanding of these factors evolves, error is reduced, and clinical studies become more meaningful. This system is very reliable and individual measurements are inexpensive. 
The sampler is relatively inexpensive and quite portable, but the monitor is neither. This limits options for some clinical studies and provides rational for future innovations.

Ammonia is an important physiologic metabolite relevant to various disease and wellness states. It is also a difficult molecule to measure in breath, which demands particular precautions be taken to obtain accurate results. Not all factors influencing ammonia are known, but progress can be difficult without accounting for these factors.

This exhaled breath ammonia method uses a fast and highly sensitive spectroscopic method known as quartz enhanced photoacoustic spectroscopy (QEPAS) that ...

Calibrated Passive Sampling - Multi-plot Field Measurements of NH₃ Emissions with a Combination of Dynamic Tube Method and Passive Samplers

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