Factors affecting nitric oxide and nitrous oxide emissions from ...

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Plate 3.1 Schematic of the reaction vessel inside LMA-3D and picture of LMA-3D (Images from: http://www.unisearch-associates.com/luminox.htm) Detection Limits: 0.1-ppbv (O3) 50 pptv (NO2, NOx). Time Response: _0.1 sec Figure 3.1 Schematic of the internal structure of the LMA-3D. The LMA-3D also has a chrome oxide converter unit in line, which oxidises NO in the sampled air to NO2. The measured amount of NO2 is then equal to NO + NO2. By analysing the air samples for (NO + NO2) and for NO2 only, the proportion of NO gas can be derived by 16
difference. The LMA-3D was also able to be used in the laboratory or in the field by using the internal battery or an external 12V DC power supply (Fig. 3.1). 3.3 Calibration procedure Calibration of the LMA-3D was critical and undertaken after consultation and personal correspondence with internationally recognized experts with considerable experience in NOx analysis i.e. Dr Rodney Venterea (University of Minnesota); Dr Pamela Matson (Stanford University)); a trace gas supplier with over 30 years of experience in the manufacture of environmental gas mixtures (Scott-Marrin Inc. (Riverside, CA)), and the instrument manufacturer (Unisearch Associates Inc.). Standard gases (NIST certified) in 22 L aluminium bottles were imported from Scott-Marrin Inc., USA. These comprised of an NO standard (1.02 ± 2% L L -1 ) in O2-free N2 containing < 0.005 L L -1 NO2 and a NO2 standard (5.07 ± 2% L L -1 ) in O2-free N2. To construct an NO standard curve the NO standard (1.02 L L -1 ) was diluted with ambient air that had passed through a Purafil ® scrubber (Purafil Inc.) to remove ambient NOx. The NO standard gas flow into the LMA-3D was varied from 2 to 30 mL min -1 and the purified ambient air flow was adjusted so that the total gas flow at the LMA-3D outlet was 1 L min -1 . This resulted in a maximum 500-fold dilution of the standard gas and produced data used in the standard curve. A mass flow controller (SIERRA Instruments, Inc. California)) was used to regulate the NO standard gas flow and a mass flow meter was used to measure the total gas flow at the LMA-3D outlet. Fig. 3.2 provides a schematic of the calibration procedure. During the construction of the standard curves the known NO standard gas mixture entering the LMA-3D created an absorbance reading which was output as a concentration in units of nL L -1 (ppbV). This concentration reading was adjusted using the span potentiometer on the LMA-3D so, that the reading (ppbV) matched the concentration of the standard gas mixture. This adjustment was made for the lowest standard only and then the other standard gas mixtures were run. Then the standard curve of the concentration reading versus the theoretical concentrations of the standard gas mixture was constructed (for both NO and NO2) (Fig. 3.3 & 3.4). These standard curves had a linear form (y = ax + b), where y was the concentration reading and x the standard gas concentration of NO or NO2. To calculate an unknown concentration (x) the linear equation was rearranged to solve for x. The LMA-3D was calibrated prior to each set of measurements. When an NO flux was determined 17
Page 1 and 2: Factors affecting nitric oxide and
Page 3 and 4: In experiment two (chapter 5) the o
Page 5 and 6: Acknowledgements I am deeply thankf
Page 7 and 8: Table of Contents Abstract.........
Page 9 and 10: 6.3.7 NOx fluxes...................
Page 11 and 12: List of Tables Table 2-1 Global Inv
Page 13 and 14: Table 7-1 Mean and S.E.M of soil pH
Page 15 and 16: Figure 4.16 Initial soil pH and NH4
Page 17 and 18: Figure 5.29 Q10(5-15 o C) values fo
Page 19 and 20: Figure 7.13 Soil N2O-N fluxes over
Page 21 and 22: Chapter 1 Introduction Managed past
Page 23 and 24: 2.1 Introduction Chapter 2 Review o
Page 25 and 26: As noted in the introduction N2O is
Page 27 and 28: Figure 2.3 Transformation of minera
Page 29 and 30: 2.5 NOx emissions from urine patche
Page 31 and 32: emissions but not NO. This at odds
Page 33 and 34: 2.6.4 Temperature Soil temperature
Page 35: 3.1 Introduction Chapter 3 Material
Page 39 and 40: NO 2 reading on LMA-3D (ppbV) 60 50
Page 41 and 42: Concentration (NO-N g m -3 ) 20 18
Page 43 and 44: depth of 7 cm and drying them in th
Page 45: 3.9 Laboratory experiments A Paparu
Page 48 and 49: 4.2 Materials and Methods 4.2.1 Soi
Page 50 and 51: 4.3 Results 4.3.1 Soil NH4 + -N con
Page 52 and 53: NO 2 - -N (g g -1 dry soil) 5 4 3 2
Page 54 and 55: NO x-N Soil pH N 2O-N NH 4 + -N NO
Page 56 and 57: 4.3.3 Soil NO3 - -N concentrations
Page 58 and 59: Table 4-7 Net NH4 + -N depletion an
Page 60 and 61: 4.3.6 Soil surface pH After urine a
Page 62 and 63: When data were pooled over all samp
Page 64 and 65: The NO-N flux was influenced by a s
Page 66 and 67: 4.3.8.1 Net NH4 + -N depletion and
Page 68 and 69: When the mean NO-N flux rate betwee
Page 70 and 71: 4.3.9 N2O fluxes In the absence of
Page 72 and 73: The cumulative N2O emissions as a p
Page 74 and 75: µg N 2O-N g -1 soil h -1 0.025 0.0
Page 76 and 77: concentrations (Tables, 4-2 - 4-5),
Page 78 and 79: 4.4 Regression analysis 4.4.1 Predi
Page 80 and 81: 4.4.2 Prediction of N2O-N When log1
Page 82 and 83: Soil surface pH increases occurred
Page 84 and 85: Unlike the NO-N fluxes, which were
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optimum pH was observed for net NO-
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Future work could further examine t
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5.2 Materials and Methods 5.2.1 Tre
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NH 4 + -N (g g -1 dry soil) 1000 80
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NH 4 + -N (g g -1 dry soil) NH 4 +
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NO 2 - -N (g g -1 dry soil) 14 12 1
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NO 2 - -N (g g-1 dry soil) NO 2 - -
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Table 5-3 Pearson correlation betwe
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5.3.3 Soil NO3 - -N concentrations
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NO 3 - -N (g g -1 dry soil) NO 3 -
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Rate of depletion/accumulation (ng
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NH4 + -N:NO 3 - -N ratio 180 160 14
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Surface soil pH 8.0 7.5 7.0 6.5 6.0
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HNO 2 (ng g -1 dry soil) 60 50 40 3
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g NO-N m -2 h -1 140 120 100 80 60
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g NO-N m -2 h -1 50 40 30 20 10 0 2
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Q 10 (15-22 o C) 80 60 40 20 0 11%
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Table 5-9 Mean NO-N flux as a perce
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These treatment effects led to a si
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g N 2O-N m -2 h -1 g N 2 O-N m -2 h
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Temperature Moisture NO-N NH 4 + -N
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Temperature Moisture NO-N NH 4 + -N
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Q 10 (15-22 o C) 100 80 60 40 20 0
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N 2O-N: NO-N 500 400 300 200 100 0
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WFPS (%) 100 80 60 40 20 0 5 10 15
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Table 5-18 The results of multiple
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Table 5-19 The significance of vari
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Table 5-22 The results of multiple
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pool. For example, when averaged ov
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depletion rate, was the soil pH. It
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0.20 g H2O g -1 soil, and temperatu
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the current experimental results. U
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134
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collected from cows at the Lincoln
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NH 4 + -N (g g -1 dry soil) 1200 10
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concentrations increasing at differ
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6.3.4 Net NH4 + -N depletion and NO
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Soil pH 8.0 7.5 7.0 6.5 6.0 5.5 5.0
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6.3.7 NOx fluxes Urine-N applicatio
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Cumulative NO-N (% of urine-N appli
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6.3.7.1 NO-N flux rate as a percent
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6.3.8 N2O fluxes The mean N2O-N flu
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Cumulative N 2 O-N ( % of uine-N ap
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6.3.10 Soil WFPS Soil moisture cont
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Table 6-6 Correlation of log10NO-N
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log 10 NO-N predicted log 10 NO-N p
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6.5 Discussion 6.5.1 Soil inorganic
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The concentrations of HNO2 were thu
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% of NO 2 - -N pool beings turnedov
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6.6 Conclusions Urine-N application
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7.2 Materials and Methods 7.2.1 Fie
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7.2.4 Meteorological data and soil
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7.3.5 Soil ammonium: nitrate ratio
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treatments showed a significant eff
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7.3.7 Theoretical HNO2 concentratio
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7.3.8 Rainfall and Water Filled Por
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7.3.10 NOx fluxes The only gas dete
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7.3.12 N2O-N: NO-N ratio There were
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Table 7-3 Results of multiple regre
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Measured/Predicted NO-N flux 400 30
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The predicted NO-N fluxes were inte
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Table 7-7 Regression coefficients d
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logN 2 O-N 4 3 2 1 0 logN 2 O-N vs
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lowering of the net NH4 + -N deplet
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approximately 6 degrees , NO3 - -N
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204
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8.2 Materials and Method Materials
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8.3.4 Net NH4 + -N depletion rates
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8.3.6 Theoretical HNO2 concentratio
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8.3.8 Soil temperature Mean soil te
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8.3.10 N2O fluxes The N2O-N fluxes
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8.4 Regression analysis 8.4.1 Predi
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The rainfall was regular (after day
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days. This was considerably higher
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to be proportional to the rate of N
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9.7 Future studies The relationshi
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Bronson, K. F., Sparling, G. P., &
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Galbally, I. E. (1989). Factor cont
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Maljanen, M., Martikkala, M., Kopon
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Scholes, M. C., Martin, R., Scholes
Page 256 and 257:
Van Slyke, D. D. (1911). A method f
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