scholarly journals A dual tracer ratio method for comparative emission measurements in an experimental dairy housing

2018 ◽  
Vol 179 ◽  
pp. 12-22 ◽  
Author(s):  
Joachim Mohn ◽  
Kerstin Zeyer ◽  
Margret Keck ◽  
Markus Keller ◽  
Michael Zähner ◽  
...  
Keyword(s):  
Ratio Method ◽  
Tracer Ratio ◽  
Dual Tracer

Quantifying NH3 and CH4 emissions from a dairy housing using backward Lagrangian stochastic modelling

2020 ◽  
Author(s):  
Christoph Häni ◽  
Marcel Bühler ◽  
Sabine Schrade ◽  
Michael Zähner ◽  
Simon Wyss ◽  
...  
Keyword(s):  
Dry Deposition ◽  
Dispersion Model ◽  
Stochastic Modelling ◽  
Calculation Model ◽  
Atmospheric Environment ◽  
Ratio Method ◽  
Dispersion Modelling ◽  
Deposition Mechanism ◽  
Field Campaign ◽  
Tracer Ratio

<p>Inverse dispersion modelling (IDM) using a backward Lagrangian stochastic (bLS) dispersion model has been successfully applied to quantify emissions from confined ground sources e.g. as for ammonia (NH<sub>3</sub>) loss after manure spreading. The most widely used bLS model for emission measurements of NH<sub>3</sub> and methane (CH<sub>4</sub>) from agricultural sources such as lagoons and livestock buildings is based on Flesch et al. (2004). For such applications, the model assumptions of a diffusive ground source within a homogeneous turbulence field, which implies absence of obstacles as e.g. buildings disturbing the flow, is clearly not fulfilled. It remains unclear to what extend these violations introduce bias into the emission estimates. Further, the model by Flesch et al. does not include deposition removal, which for NH<sub>3</sub>, can induce an underestimation of the emission from the source (Häni et al., 2018). Häni et al. extended the standard bLS calculation model with an optional dry deposition mechanism.</p><p>In a field campaign between mid-September and mid-December 2018, CH<sub>4</sub> and NH<sub>3</sub> emissions from a natural ventilated dairy housing with 40 cows were quantified using the IDM method with the bLS model by Häni et al. (2018). From the three-month period, results for 63 measurement days at 30-minute resolution were evaluated and thereof 71% of the data points were discarded from the emission calculation due to inapplicable turbulence conditions or instrument failure.</p><p>NH<sub>3</sub> and CH<sub>4</sub> concentrations were analysed with open-path instruments (NH<sub>3</sub>: miniDOAS,; CH<sub>4</sub>: GasFinder, Boreal Laser, Inc., Edmonton, Alberta, Canada) (aligned in parallel) with 50 m path lengths (distance between sensor and reflector). During part of the field campaign (24 days), simultaneous in-house measurements of CH<sub>4</sub> and NH<sub>3</sub> emissions using the tracer ratio method (iTM) (SF<sub>6</sub> and SF<sub>5</sub>CF<sub>3</sub>, Mohn et al., 2018) were conducted and results compared with the estimates retrieved by the IDM method. Overall, the results from the IDM method compare well to the results of the in-house measurements, with mean daily emissions of 18.3 kg CH<sub>4</sub>/d (IDM) and 17.9 kg CH<sub>4</sub>/d (iTM) and 1.08 kg NH<sub>3</sub>/d (IDM) and 1.56 kg NH<sub>3</sub>/d (iTM), respectively. Regarding NH<sub>3</sub>, the IDM method was run without the inclusion of a dry deposition mechanism. First results from IDM calculations with the inclusion of dry deposition indicate, that dry deposition modelling may explain the difference in NH<sub>3</sub> emissions between the IDM method and the iTM.</p><p><strong>References</strong></p><p>Flesch, T. K., Wilson, J. D., Harper, L. A., Crenna, B. P., and Sharpe, R. R.: Deducing ground-to-air emissions from observed trace gas concentrations: A field trial, J. Appl. Meteorol., 43, 487–502, 2004.</p><p>Häni, C., Flechard, C., Neftel, A., Sintermann, J., and Kupper, T.: Accounting for Field-Scale Dry Deposition in Backward Lagrangian Stochastic Dispersion Modelling of NH3 Emissions, Atmosphere, 9, 146, 2018.</p><p>Mohn, J., Zeyer, K., Keck, M., Keller, M., Zähner, M., Poteko, J., Emmenegger, L., and Schrade, S.: A dual tracer ratio method for comparative emission measurements in an experimental dairy housing, Atmospheric Environment, 179, 12–22, 2018.</p>

Determination of anthropogenic emissions in the Augsburg area by the source–tracer-ratio method

2002 ◽  
Vol 36 ◽  
pp. 95-107 ◽  
Author(s):  
Michael Möllmann-Coers ◽  
Dieter Klemp ◽  
Katja Mannschreck ◽  
Franz Slemr
Keyword(s):  
Ratio Method ◽  
Anthropogenic Emissions ◽  
Tracer Ratio

scholarly journals On the use of satellite derived CH<sub>4</sub> / CO<sub>2</sub> columns in CH<sub>4</sub> flux inversions

2015 ◽  
Vol 15 (6) ◽  
pp. 8801-8838
Author(s):  
S. Pandey ◽  
S. Houweling ◽  
M. Krol ◽  
I. Aben ◽  
T. Röckmann
Keyword(s):  
Inverse Modeling ◽  
Surface Fluxes ◽  
Surface Measurement ◽  
Ratio Method ◽  
Co2 Fluxes ◽  
Hard Constraints ◽  
Surface Measurements ◽  
Ratio Approach ◽  
Dual Tracer ◽  
Better Than

Abstract. We present a new method for assimilating CH4 measurements from satellites, which have been retrieved using the proxy-ratio approach, for inverse modeling of CH4 fluxes. Unlike conventional approaches, in which retrieved CH4 / CO2 ratios are multiplied by model derived total column CO2 and only the resulting CH4 is assimilated, our method assimilates the ratio of CH4 and CO2 directly and is therefore called the ratio method. It is a dual tracer inversion, in which surface fluxes of CH4 and CO2 are optimized simultaneously. The optimization of CO2 fluxes turns the hard constraint of prescribing model derived CO2 fields into a weak constraint on CO2, which allows us to account for uncertainties in CO2. The method has been successfully tested in a synthetic inversion setup using the TM5-4DVAR inverse modeling system. We show that the ratio method is able to reproduce assumed true CH4 and CO2 fluxes starting from a prior, which is derived by perturbing the true fluxes randomly. We compare the performance of the ratio method with that of the traditional proxy approach and the use of only surface measurements for estimating CH4 fluxes. Our results confirm that the optimized CH4 fluxes are sensitive to the treatment of CO2, and that hard constraints on CO2 may significantly compromise results that are obtained for CH4. We see that the relative performance of ratio and proxy methods have a regional dependence. The ratio method performs better than the proxy method in regions where the CO2 fluxes are most uncertain. However, both ratio and proxy methods perform better than the surface measurement-only inversion confirming the potential of space borne measurements for accurately determining fluxes of CH4 and other GHGs.

scholarly journals On the use of satellite-derived CH<sub>4</sub> : CO<sub>2</sub> columns in a joint inversion of CH<sub>4</sub> and CO<sub>2</sub> fluxes

2015 ◽  
Vol 15 (15) ◽  
pp. 8615-8629 ◽  
Author(s):  
S. Pandey ◽  
S. Houweling ◽  
M. Krol ◽  
I. Aben ◽  
T. Röckmann
Keyword(s):  
Joint Inversion ◽  
Surface Fluxes ◽  
Surface Measurement ◽  
Ratio Method ◽  
Co2 Fluxes ◽  
Hard Constraints ◽  
Surface Measurements ◽  
Total Column ◽  
Dual Tracer ◽  
Better Than

Abstract. We present a method for assimilating total column CH4 : CO2 ratio measurements from satellites for inverse modeling of CH4 and CO2 fluxes using the variational approach. Unlike conventional approaches, in which retrieved CH4 : CO2 are multiplied by model-derived total column CO2 and only the resulting CH4 is assimilated, our method assimilates the ratio of CH4 and CO2 directly and is therefore called the ratio method. It is a dual tracer inversion, in which surface fluxes of CH4 and CO2 are optimized simultaneously. The optimization of CO2 fluxes turns the hard constraint of prescribing model-derived CO2 fields into a weak constraint on CO2, which allows us to account for uncertainties in CO2. The method has been successfully tested in a synthetic inversion setup. We show that the ratio method is able to reproduce assumed true CH4 and CO2 fluxes starting from a prior, which is derived by perturbing the true fluxes randomly. We compare the performance of the ratio method with that of the traditional proxy approach and the use of only surface measurements for estimating CH4 fluxes. Our results confirm that the optimized CH4 fluxes are sensitive to the treatment of CO2, and that hard constraints on CO2 may significantly compromise results that are obtained for CH4. We find that the relative performance of ratio and proxy methods have a regional dependence. The ratio method performs better than the proxy method in regions where the CO2 fluxes are most uncertain. However, both ratio and proxy methods perform better than the surface-measurement-only inversion, confirming the potential of spaceborne measurements for accurately determining fluxes of CH4 and other greenhouse gases (GHGs).

scholarly journals In-situ measurements of atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) at the Shangdianzi regional background station, China

2012 ◽  
Vol 12 (21) ◽  
pp. 10181-10193 ◽  
Author(s):  
B. Yao ◽  
M. K. Vollmer ◽  
L. X. Zhou ◽  
S. Henne ◽  
S. Reimann ◽  
...  
Keyword(s):  
Ratio Method ◽  
High Concentration ◽  
Urban Sector ◽  
Mixing Ratios ◽  
Regional Background ◽  
Hfc 134A ◽  
The Mean ◽  
Hfc 152A ◽  
Tracer Ratio

Abstract. Atmospheric hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) were measured in-situ at the Shangdianzi (SDZ) Global Atmosphere Watch (GAW) regional background station, China, from May 2010 to May 2011. The time series for five HFCs and three PFCs showed occasionally high-concentration events while background conditions occurred for 36% (HFC-32) to 83% (PFC-218) of all measurements. The mean mixing ratios during background conditions were 24.5 ppt (parts per trillion, 10−12, molar) for HFC-23, 5.86 ppt for HFC-32, 9.97 ppt for HFC-125, 66.0 ppt for HFC-134a, 9.77 ppt for HFC-152a, 79.1 ppt for CF4, 4.22 ppt for PFC-116, and 0.56 ppt for PFC-218. The background mixing ratios for the compounds at SDZ are consistent with those obtained at mid to high latitude sites in the Northern Hemisphere. North-easterly winds were associated with negative contributions to atmospheric HFC and PFC loadings (mixing ratio anomalies weighted by time associated with winds in a given sector), whereas south-westerly advection (urban sector) showed positive loadings. Chinese emissions estimated by a tracer ratio method using carbon monoxide as tracer were 3.6 ± 3.2 kt yr−1 for HFC-23, 4.3 ± 3.6 kt yr−1 for HFC-32, 2.7 ± 2.3 kt yr−1 for HFC-125, 6.0 ± 5.6 kt yr−1 for HFC-134a, 2.0 ± 1.8 kt yr−1 for HFC-152a, 2.4 ± 2.1 kt yr−1 for CF4, 0.27 ± 0.26 kt yr−1 for PFC-116, and 0.061 ± 0.095 kt yr−1 for PFC-218. The lower HFC-23 emissions compared to earlier studies may be a result of the HFC-23 abatement measures taken as part of Clean Development Mechanism (CDM) projects that started in 2005.

scholarly journals Zinc Absorption From Agronomically Biofortified Wheat Is Similar to Post-Harvest Fortified Wheat and Is a Substantial Source of Bioavailable Zinc in Humans

2019 ◽  
Vol 149 (5) ◽  
pp. 840-846 ◽  
Author(s):  
Coralie Signorell ◽  
Michael B Zimmermann ◽  
Ismail Cakmak ◽  
Rita Wegmüller ◽  
Christophe Zeder ◽  
...  
Keyword(s):  
Mixed Models ◽  
Extraction Rate ◽  
Ratio Method ◽  
Zinc Absorption ◽  
Limited Data ◽  
Men And Women ◽  
Labeling Method ◽  
Foliar Zinc Application ◽  
Zinc Application ◽  
Tracer Ratio

ABSTRACT Background Limited data exist on human zinc absorption from wheat biofortified via foliar (FBW) or root (hydroponically fortified wheat, HBW) zinc application. Stable isotope labels added at point of consumption (extrinsic labeling) might not reflect absorption from native zinc obtained by intrinsic labeling. Objectives We measured fractional and total zinc absorption (FAZ, TAZ) in FBW and HBW wheat, compared with control wheat (CW) and fortified wheat (FW). The effect of labeling method was assessed in HBW (study 1), and the effect of milling extraction rate (EXR, 80% and 100%) in FBW (studies 2 and 3). Methods Generally healthy adults (n = 71, age: 18–45 y, body mass index: 18.5–25 kg/m2) were allocated to 1 of the studies, in which they served as their own controls. In study 1, men and women consumed wheat porridges colabeled intrinsically and extrinsically with 67Zn and 70Zn. In studies 2 and 3, women consumed wheat flatbreads (chapatis) labeled extrinsically. Zinc absorption was measured with the oral to intravenous tracer ratio method with a 4-wk wash-out period between meals. Data were analyzed with linear mixed models. Results In study 1 there were no differences in zinc absorption from extrinsic versus intrinsic labels in either FW or HBW. Similarly, FAZ and TAZ from FW and HBW did not differ. TAZ was 70–76% higher in FW and HBW compared with CW (P < 0.01). In studies 2 and 3, TAZ from FW and FBW did not differ but was 20–48% higher compared with CW (P < 0.001). Extraction rate had no effect on TAZ. Conclusions Colabeling demonstrates that extrinsic zinc isotopic labels can be used to accurately quantify zinc absorption from wheat in humans. Biofortification through foliar zinc application, root zinc application, or fortification provides higher TAZ compared with unfortified wheat. In biofortified wheat, extraction rate (100–80%) has a limited impact on total zinc absorption. These studies were registered on clinicaltrials.gov (NCT01775319).

X-Ray Analysis of Frozen Hydrated Sections:The Unconventional Approach

1982 ◽  
Vol 40 ◽  
pp. 754-757
Author(s):  
R. Beeuwkes ◽  
A. Saubermann ◽  
P. Echlin ◽  
S. Churchill
Keyword(s):  
Ratio Method ◽  
Frozen Sections ◽  
Technical Problems ◽  
Sample Handling ◽  
X Ray ◽  
Common Group ◽  
Ideal Method ◽  
Classic Paper ◽  
Physical Principles ◽  
The Ideal

Fifteen years ago, Hall described clearly the advantages of the thin section approach to biological x-ray microanalysis, and described clearly the ratio method for quantitive analysis in such preparations. In this now classic paper, he also made it clear that the ideal method of sample preparation would involve only freezing and sectioning at low temperature. Subsequently, Hall and his coworkers, as well as others, have applied themselves to the task of direct x-ray microanalysis of frozen sections. To achieve this goal, different methodological approachs have been developed as different groups sought solutions to a common group of technical problems. This report describes some of these problems and indicates the specific approaches and procedures developed by our group in order to overcome them. We acknowledge that the techniques evolved by our group are quite different from earlier approaches to cryomicrotomy and sample handling, hence the title of our paper. However, such departures from tradition have been based upon our attempt to apply basic physical principles to the processes involved. We feel we have demonstrated that such a break with tradition has valuable consequences.

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