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International Workshop on Ammonia Measurements (IWAM)
Hensen, A.; Neftel, A.; Famulari, D.; Carozzi, M.; Jonker, H.; Erisman, J.W.; Huijsmans, J.; Mosquera, J.; Lantinga, E.; Berkhout, A.J.C.; Haan, B. de
Gepubliceerd door: Publicatie datum:
ECN Environment & Energy Engineering 13-4-2015
ECN publicatienummer: Publicatie type:
ECN-E--14-052 ECN rapport
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In 2011 Sintermann et al published a paper on NH3 emissions after manure application. The paper provided an overview of emission measurements and concluded that the choice of measurement setup could have an effect on the estimated emission level. Furthermore the different measurements options were compared and an assessment was made on potential biases for the different methods. This paper triggered a discussion in Switzerland and in the Netherlands on this issue. In June 2014 a workshop was organised in Schagen, the Netherlands, to assess the current state of knowledge on NH3 emission of different application techniques for manure in the fields. The workshop was organised to evaluate several hypotheses that might lead to systematic bias in emission estimates from measurements. At the workshop the hypotheses were introduced and addressed with a set of presentations after which a discussion on the state of knowledge was held. The findings of the workshop are documented in this report. Apart from the workshop report, post workshop comments are included to address the issues that were discussed with new information and or measurements available since the Schagen meeting. The workshop addressed the following issues: • The effect of turbulent transport over a manured plot. • The oasis effect that might cause different parts of the plot to emit differently. • The effect of time integrated measurements. • The effect of wind speed reduction within the vegetation (displacement height). • The effect of persistent spatial structures in turbulence over a manured field. • Effect of vertical dispersion and consequences for height of measurement. Apart from these potential biases, new techniques that could be helpful with interpretation of measurements were presented and discussed: • The use of numerical simulations to better understand transport of gas. • The use of dispersion models for data evaluation purposes. Main conclusions were that turbulent transport and the displacement height should be accounted for since these generate a systematic bias in the data. To precisely quantify the corrections extra research is needed. At the workshop it was concluded that turbulent transport systematically overestimates emissions (between 0-20%). Numerical simulations and preliminary experiments in suggest an overestimation > 10%. Published data thus far suggests that this effect will be below 10%. Based on preliminary calculations not taking into account the displacement height will lead to an overestimation of between 1-2% on the measured ammonia emissions. This should be further evaluated using all available datasets. The effect of time integration has not been quantified yet, it is not clear whether this will lead to a systematic (bias) effect, and in case of systematic how much this will be. The oasis effect was concluded to be insignificant compared to other effects that create non uniform spatial emission from a field.

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