Development of a low-cost system for measuring conditional time-averaged gradients of SO2 and NH3

Famulari, D.; Fowler, D.; Nemitz, Eiko; Hargreaves, K. J.; Storeton-West, Robert; Rutherford, G. H.; Tang, Y. S.; Sutton, Mark A.; Weston, Keith

doi:10.1007/s10661-008-0723-6

Cited by 37 publications

(29 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To obtain local, field-scale estimates of R c , two COTAG systems (conditional time-averaged gradient systems; Famulari et al, 2010) were operated at the centre of the grazed field for 1.5 years, allowing R c to be estimated from calculations of R a and R b and time-integrated measurements of NH 3 concentration (C), flux (−F ) and v d (Eq. 3).…”

Section: Modelling Of Dry Deposition Within the Source Areamentioning

confidence: 99%

Ammonia emissions from a grazed field estimated by miniDOAS measurements and inverse dispersion modelling

et al. 2017

View full text Add to dashboard Cite

Abstract. Ammonia (NH 3 ) fluxes were estimated from a field being grazed by dairy cattle during spring by applying a backward Lagrangian stochastic model (bLS) model combined with horizontal concentration gradients measured across the field. Continuous concentration measurements at field boundaries were made by open-path miniDOAS (differential optical absorption spectroscopy) instruments while the cattle were present and for 6 subsequent days. The deposition of emitted NH 3 to "clean" patches on the field was also simulated, allowing both "net" and "gross" emission estimates, where the dry deposition velocity (v d ) was predicted by a canopy resistance (R c ) model developed from local NH 3 flux and meteorological measurements. Estimated emissions peaked during grazing and decreased after the cattle had left the field, while control on emissions was observed from covariance with temperature, wind speed and humidity and wetness measurements made on the field, revealing a diurnal emission profile. Large concentration differences were observed between downwind receptors, due to spatially heterogeneous emission patterns. This was likely caused by uneven cattle distribution and a low grazing density, where "hotspots" of emissions would arise as the cattle grouped in certain areas, such as around the water trough. The spatial complexity was accounted for by separating the model source area into sub-sections and optimising individual source area coefficients to measured concentrations. The background concentration was the greatest source of uncertainty, and based on a sensitivity/uncertainty analysis the overall uncertainty associated with derived emission factors from this study is at least 30-40 %.Emission factors can be expressed as 6 ± 2 g NH 3 cow −1 day −1 , or 9 ± 3 % of excreted urine-N emitted as NH 3 , when deposition is not simulated and 7 ± 2 g NH 3 cow −1 day −1 , or 10 ± 3 % of excreted urine-N emitted as NH 3 , when deposition is included in the gross emission model. The results suggest that around 14 ± 4 % of emitted NH 3 was deposited to patches within the field that were not affected by urine or dung.

show abstract

Section: Modelling Of Dry Deposition Within the Source Areamentioning

confidence: 99%

Ammonia emissions from a grazed field estimated by miniDOAS measurements and inverse dispersion modelling

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Long-term concentration measurements of NH 3 are now well handled by the use of short-path passive samplers developed by , or active denuders, which have both been used for concentration monitoring for years (Tang et al, , 2009). These active denuders can be adapted for measuring fluxes based on conditional sampling like the conditional time-averaged gradient method (COTAG) (Famulari et al, 2010), which is a useful method but only adapted for large fields (≥ 0.5 ha). The passive samplers have also been shown to be adapted for inverse modelling estimations of NH 3 sources for large fields (Carozzi et al, 2013b;Ferrara et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a new inference method for estimating ammonia volatilisation from multiple agronomic plots

Loubet¹,

Carozzi²,

Voylokov³

et al. 2018

Biogeosciences

View full text Add to dashboard Cite

Abstract. Tropospheric ammonia (NH 3 ) is a threat to the environment and human health and is mainly emitted by agriculture. Ammonia volatilisation following application of nitrogen in the field accounts for more than 40 % of the total NH 3 emissions in France. This represents a major loss of nitrogen use efficiency which needs to be reduced by appropriate agricultural practices. In this study we evaluate a novel method to infer NH 3 volatilisation from small agronomic plots consisting of multiple treatments with repetition. The method is based on the combination of a set of NH 3 diffusion sensors exposed for durations of 3 h to 1 week and a shortrange atmospheric dispersion model, used to retrieve the emissions from each plot. The method is evaluated by mimicking NH 3 emissions from an ensemble of nine plots with a resistance analogue-compensation point-surface exchange scheme over a yearly meteorological database separated into 28-day periods. A multifactorial simulation scheme is used to test the effects of sensor numbers and heights, plot dimensions, source strengths, and background concentrations on the quality of the inference method. We further demonstrate by theoretical considerations in the case of an isolated plot that inferring emissions with diffusion sensors integrating over daily periods will always lead to underestimations due to correlations between emissions and atmospheric transfer. We evaluated these underestimations as −8 % ± 6 % of the emissions for a typical western European climate. For multiple plots, we find that this method would lead to median underestimations of −16 % with an interquartile [−8-22 %] for two treatments differing by a factor of up to 20 and a control treatment with no emissions. We further evaluate the methodology for varying background concentrations and NH 3 emissions patterns and demonstrate the low sensitivity of the method to these factors. The method was also tested in a real case and proved to provide sound evaluations of NH 3 losses from surface applied and incorporated slurry. We hence showed that this novel method should be robust and suitable for estimating NH 3 emissions from agronomic plots. We believe that the method could be further improved by using Bayesian inference and inferring surface concentrations rather than surface fluxes. Validating against controlled source is also a remaining challenge.

show abstract

“…Various analytical techniques and different flux measurement methods have been applied simultaneously often requiring expensive and maintenance-intensive systems. For some reactive species, simpler integral monitoring systems are also used (Famulari et al, 2009;Flechard et al, 2011), but they yield only a low time resolution of one month.…”

Section: Introductionmentioning

confidence: 99%

Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance

Ammann

Wolff

Marx³

et al. 2012

Biogeosciences

View full text Add to dashboard Cite

Abstract. The (net) exchange of reactive nitrogen (N r ) with the atmosphere is an important driver for ecosystem productivity and greenhouse gas exchange. The exchange of airborne N r includes various trace compounds that usually require different specific measurement techniques, and up to now fast response instruments suitable for eddy covariance measurements are only available for few of these compounds.Here we present eddy covariance flux measurements with a recently introduced converter (TRANC) for the sum of all N r compounds ( N r ). Measurements were performed over a managed grassland field with phases of net emission and net deposition of N r and alternating dominance of oxidized (NO X ) and reduced species (NH 3 ). Spectral analysis of the eddy covariance data exhibited the existence of covariance function peaks at a reasonable time lag related to the sampling tube residence time under stationary conditions. Using ogive analysis, the high-frequency damping was quantified to 19 %-26 % for a low measurement height of 1.2 m and to about 10 % for 4.8 m measurement height.N r concentrations and fluxes were compared to parallel NO and NO 2 measurements by dynamic chambers and NH 3 measurements by the aerodynamic gradient technique. The average concentration results indicate that the main compounds NO 2 and NH 3 were converted by the TRANC system with an efficiency of near 100 %. With an optimised sample inlet also the fluxes of these compounds were recovered reasonably well including net deposition and net emission phases. The study shows that the TRANC system is suitable for fast response measurements of oxidized and reduced nitrogen compounds and can be used for continuous eddy covariance flux measurements of total reactive nitrogen.

show abstract

Development of a low-cost system for measuring conditional time-averaged gradients of SO2 and NH3

Cited by 37 publications

References 28 publications

Ammonia emissions from a grazed field estimated by miniDOAS measurements and inverse dispersion modelling

Ammonia emissions from a grazed field estimated by miniDOAS measurements and inverse dispersion modelling

Evaluation of a new inference method for estimating ammonia volatilisation from multiple agronomic plots

Measuring the biosphere-atmosphere exchange of total reactive nitrogen by eddy covariance

Contact Info

Product

Resources

About