Binnen het project Klimaat voor Ruimte is gekeken of de broeikasgasemissies in het landelijke geb... more Binnen het project Klimaat voor Ruimte is gekeken of de broeikasgasemissies in het landelijke gebied beinvloed kunnen worden. Onderzocht is of mitigatie mogelijk is door emissies terug te dringen in de veenweidegebieden en door de vastlegging van koolstof in bossen te verhogen. Daarnaast is bepaald wat de effecten zijn van het Nederlandse landgebruik in de toekomst (scenario’s) op de broeikasgasemissies.
Onderzocht is of mitigatie mogelijk terug te dringen is in de veenweidegebieden en of het door de... more Onderzocht is of mitigatie mogelijk terug te dringen is in de veenweidegebieden en of het door de vastlegging van koolstof in bossen te verhogen is. Daarnaast is bepaald wat de effecten zijn van het Nederlandse landgebruik in de toekomst (scenario's) op de broeikasemissies
Measuring ammonia emissions from manured fields The Dutch National Institute for Public Health an... more Measuring ammonia emissions from manured fields The Dutch National Institute for Public Health and the Environment (RIVM)and the Energy Research Centre of the Netherlands (ECN) have developed two novel instruments to measure atmospheric ammonia emissions from manured fields-a lidar (light detection and ranging) and a TDL (tuneable diode laser). Insight into ammonia emissions is necessary in order to comply with European Union policy that current emission levels be reduced by 2010. Ammonia causes the eutrophication and acidification of nature reserves and contributes to the formation of particulate matter. The measurements obtained using the lidar and TDL are in good agreement. On grassland, both instruments measured relatively high levels of emissions relative to those obtained in the past using other instruments, but the values fell within the range of those past measurements. On arable land, the measurements obtained using the new methods did not differ from average emission levels based on previous measurements. The new instruments revealed that ammonia emissions from a manured field peak later than expected: not directly after the manure is applied, but 1-2 hours later. Consequently, with the aim to improve national emission numbers, the use of a model that explicitly takes into account the most important environmental variables is recommended.
Closed (non-steady state) chamber measurements are often used to determine the gas exchange of N ... more Closed (non-steady state) chamber measurements are often used to determine the gas exchange of N 2 O. Many researchers have addressed the underestimation of the emission estimates obtained from closed chamber measurements when using linear regression methods. However, the linear regression method is still usually applied to derive the flux. The importance of using non-linear regression methods is demonstrated with data from four fertilizing events each consisting of 1 month of automatic chamber measurements at Cabauw in the Netherlands in the period from July 2005 to July 2006. It is presented that the cumulative emission estimates with the exponential regression method are close to the cumulative emissions estimates with the intercept method. The linear estimates differ by up to 60% of the estimates with the exponential method. The performance of each method is validated using a C 2 H 6 tracer and a goodness-of-fit analysis. The goodness-of-fit is much better for the exponential than the linear regression method. The systematic error due to linear regression is of the same order as the estimated uncertainty due to temporal variation. Therefore, closed-chamber data should be tested for non-linearity and an appropriate method should be used to calculate the flux.
Journal of Integrative Environmental Sciences, 2010
This article describes two different visualisation instruments that can be used for awareness rai... more This article describes two different visualisation instruments that can be used for awareness raising and educational purposes: Nitrogenius and the N-visualisation tool. Both instruments aim to convey the complex interactions that occur in the nitrogen (N) cycle and the need for integrated measures when aiming to reduce Nrelated environmental problems such as eutrophication, acidification or global warming. Nitrogenius was developed in the year 2000. This four-player computer ''game'' focuses on the Dutch N problems caused by N 2 O, NH 3 and NO x emissions as well as nitrate in surface and ground water. Underlying the glossy user interface is a set of comprehensive models and a database with potential measures that were considered to be feasible at the time. Since 2000, the model has been used for educational purposes annually at Wageningen University. About 150 MSc students played the game, with the aim to solve the N-related problems in the Netherlands. This article analyses these games, and presents the surprising correlation for the period 2000-2007 with the actual environmental trends in the Netherlands. The second tool is an N-visualisation tool that was developed in 2007. This tool provides both a historic overview of the nitrogen issue and demonstrates the effect of seven potential measures on the world wide N cycle. The effects of increased biomass use and intensification of agriculture are examples of included measures. The net effect on global warming, food availability and biodiversity are output parameters of this instrument. The calculations and assumptions underlying this tool are easily accessible through an open source spreadsheet. This tool was used in 2008 and 2009 at Wageningen University for educational purposes. The pros and cons of both games for awareness raising and educational purposes will be discussed.
In the marine atmosphere, small ions are produced mainly by cosmic radiation. The production rate... more In the marine atmosphere, small ions are produced mainly by cosmic radiation. The production rate q of small ion pairs at sea level is modulated in time by the 11-year sunspot cycle. Cosmic radiation is deflected in the magnetosphere by Lorentz forces and, consequently, q is also modulated with respect to geomagnetic latitude. Comparing empirical values of q, observed on different locations at different times, only makes sense when both the solar and the latitude modulations are accounted for. A review of the literature on cosmic radiation at sea level has resulted in a most probable parameterization of both of these modulations in the present study. 1.
This paper addresses two hypothesis that try to explain the difference observed between the estim... more This paper addresses two hypothesis that try to explain the difference observed between the estimated NH 3 emission levels in The Netherlands and those indicated by atmospheric measurements, the so called 'ammonia gap': the role of SO 2 emissions regulating ambient NH 3 concentrations through co-deposition, and long-term NH 3 emissions after slurry injection. It was found that throughfall measurements of NH 4 + could not be used as indicator for changes in NH 3 emissions. The throughfall deposition of NH 4 + is in close equilibrium to SO 4 2 − and NO 3 − and is thus regulated by the equilibrium of ambient NH 3 and NH 4 + in wet deposition and canopy water layers. When SO 2 emissions decrease, the amount of available SO 4 2 − decreases, which imposes a limit on the deposition of (NH 4) 2 SO 4. Long-term emissions of NH 3 after application of manure were monitored using a new technique, which continuously measures the concentration of NH 3 in a cross-section of the emission plume downwind of the source. The emissions could be registered for 3 weeks after application of manure. The results indicate that the long-term emissions only contribute 1-2% to the total emission level. Both the effect of SO 2 on the NH 3 deposition levels and the long-term emission fluxes are not enough to explain the observed ammonia gap. It seems that several counteracting effects, some of them emerging from the new emission reduction regulations, contribute to the ammonia gap. An integrated approach to abate ammonia emissions is, therefore, needed. The implementation and regulation of production ceilings for reactive nitrogen might be a good option.
Methane emissions of large parts of NW-Europe are derived from continuous concentration measureme... more Methane emissions of large parts of NW-Europe are derived from continuous concentration measurements at one sample site (Cabauw tower, The Netherlands) using the COMET transport model. This approach can be used as an independent check of emission estimates based on statistical information. COMET is a two-layer Lagrangian atmospheric transport model that describes the uptake of methane emissions in the mixing layer along a backward trajectory path and the exchange with a reservoir layer during mixing layer height changes. In inverse mode a Singular Value Decomposition (SVD) matrix inversion technique is used to calculate the emissions of a limited number of source areas using four years of 6-hourly concentration data (1993±1996) at Cabauw. The calculated emissions compare well with the current emission inventory data for the Netherlands and the surrounding countries. For the Netherlands a yearly emission of 757 Gg of methane is calculated, excluding the emissions from oil and gas mining at the North Sea continental shelf.
In-canopy turbulence is a required input to study pollutant cycling and chemistry within plant ca... more In-canopy turbulence is a required input to study pollutant cycling and chemistry within plant canopies and to link concentrations and sources. Despite the importance of grasslands worldwide, most previous work has focused on forests and crops. Here, turbulence parameters in a mature agricultural grassland canopy were measured with a combination of a small ultrasonic anemometer, hotwire anemometry and a radon (Rn) tracer technique, as part of a measurement to study ammonia (NH 3) exchange with grassland. The measurements are used to derive vertical profiles of basic turbulent parameters, for quadrant-hole analysis of the two-parametric frequency distributions of u-w and to derive in-canopy eddy diffusivities as input for models of incanopy tracer transport. The results are in line with previous measurements on taller canopies, but shows increased decoupling between in-canopy flow and above-canopy turbulence. The comparison of sonic anemometry and Rn measurements implies that Lagrangian timescales must decrease sharply at the ground, with important implications for estimating the magnitude of ground-level and soil emissions from concentration measurements. Atmospheric stability above and within the canopy has little influence on the standard deviation of vertical wind component inside the canopy. Use of the turbulence parameters in an analytical Lagrangian frame
Commonly, the micrometeorological parameters that underline the calculations of surface atmospher... more Commonly, the micrometeorological parameters that underline the calculations of surface atmosphere exchange fluxes (e.g. friction velocity and sensible heat flux) and parameters used to model exchange fluxes with SVATtype parameterisations (e.g. latent heat flux and canopy temperature) are measured with a single set of instrumentation and are analysed with a single methodology. This paper evaluates uncertainties in these measurements with a single instrument, by comparing the independent results from nine different institutes during the international GRAMINAE integrated field experiment over agricultural grassland near Braunschweig, Lower Saxony, Germany. The paper discusses uncertainties in measuring friction velocity, sensible and latent heat fluxes, canopy temperature and investigates the energy balance closure at this site. Although individual 15-min flux calculations show a large variability between the instruments, when averaged over the campaign, fluxes agree within 2% for momentum and 11% for sensible heat. However, the spread in estimates of latent heat flux (λE) is
Improved data on biosphere-atmosphere exchange are fundamental to understanding the production an... more Improved data on biosphere-atmosphere exchange are fundamental to understanding the production and fate of ammonia (NH 3) in the atmosphere. The GRAMINAE Integrated Experiment combined novel measurement and modelling approaches to provide the most comprehensive analysis of the interactions to date. Major intercomparisons of micrometeorological parameters and NH 3 flux measurements using the aerodynamic gradient method and relaxed eddy accumulation (REA) were conducted. These showed close agreement, though the REA systems proved insufficiently precise to investigate vertical flux
During recent years, it has become clear that ammonia is an important gas in relation to di!erent... more During recent years, it has become clear that ammonia is an important gas in relation to di!erent environmental issues, such as acidi"cation, eutrophication, human health and climate change (through particle formation). Therefore, there is a growing need to develop and apply instrumentation suitable for research into emission, dispersion, conversion and deposition of ammonia and ammonium. Recently, several instruments were developed suitable for measuring concentrations in ambient conditions even at very low levels, such as ammonia sensors suitable for monitoring and research, deposition measuring systems and aerosol samplers for on-line measurement of aerosol composition. These instruments have been tested and applied in a number of "eld studies. These studies include dry deposition measurements, ammonium nitrate studies in relation to the (in)direct aerosol e!ect, emission studies and policy evaluation with concentration and deposition monitoring data. The policy evaluation study showed that the measures to reduce ammonia emissions were not as successful as projected beforehand by statistical studies.
Binnen het project Klimaat voor Ruimte is gekeken of de broeikasgasemissies in het landelijke geb... more Binnen het project Klimaat voor Ruimte is gekeken of de broeikasgasemissies in het landelijke gebied beinvloed kunnen worden. Onderzocht is of mitigatie mogelijk is door emissies terug te dringen in de veenweidegebieden en door de vastlegging van koolstof in bossen te verhogen. Daarnaast is bepaald wat de effecten zijn van het Nederlandse landgebruik in de toekomst (scenario’s) op de broeikasgasemissies.
Onderzocht is of mitigatie mogelijk terug te dringen is in de veenweidegebieden en of het door de... more Onderzocht is of mitigatie mogelijk terug te dringen is in de veenweidegebieden en of het door de vastlegging van koolstof in bossen te verhogen is. Daarnaast is bepaald wat de effecten zijn van het Nederlandse landgebruik in de toekomst (scenario's) op de broeikasemissies
Measuring ammonia emissions from manured fields The Dutch National Institute for Public Health an... more Measuring ammonia emissions from manured fields The Dutch National Institute for Public Health and the Environment (RIVM)and the Energy Research Centre of the Netherlands (ECN) have developed two novel instruments to measure atmospheric ammonia emissions from manured fields-a lidar (light detection and ranging) and a TDL (tuneable diode laser). Insight into ammonia emissions is necessary in order to comply with European Union policy that current emission levels be reduced by 2010. Ammonia causes the eutrophication and acidification of nature reserves and contributes to the formation of particulate matter. The measurements obtained using the lidar and TDL are in good agreement. On grassland, both instruments measured relatively high levels of emissions relative to those obtained in the past using other instruments, but the values fell within the range of those past measurements. On arable land, the measurements obtained using the new methods did not differ from average emission levels based on previous measurements. The new instruments revealed that ammonia emissions from a manured field peak later than expected: not directly after the manure is applied, but 1-2 hours later. Consequently, with the aim to improve national emission numbers, the use of a model that explicitly takes into account the most important environmental variables is recommended.
Closed (non-steady state) chamber measurements are often used to determine the gas exchange of N ... more Closed (non-steady state) chamber measurements are often used to determine the gas exchange of N 2 O. Many researchers have addressed the underestimation of the emission estimates obtained from closed chamber measurements when using linear regression methods. However, the linear regression method is still usually applied to derive the flux. The importance of using non-linear regression methods is demonstrated with data from four fertilizing events each consisting of 1 month of automatic chamber measurements at Cabauw in the Netherlands in the period from July 2005 to July 2006. It is presented that the cumulative emission estimates with the exponential regression method are close to the cumulative emissions estimates with the intercept method. The linear estimates differ by up to 60% of the estimates with the exponential method. The performance of each method is validated using a C 2 H 6 tracer and a goodness-of-fit analysis. The goodness-of-fit is much better for the exponential than the linear regression method. The systematic error due to linear regression is of the same order as the estimated uncertainty due to temporal variation. Therefore, closed-chamber data should be tested for non-linearity and an appropriate method should be used to calculate the flux.
Journal of Integrative Environmental Sciences, 2010
This article describes two different visualisation instruments that can be used for awareness rai... more This article describes two different visualisation instruments that can be used for awareness raising and educational purposes: Nitrogenius and the N-visualisation tool. Both instruments aim to convey the complex interactions that occur in the nitrogen (N) cycle and the need for integrated measures when aiming to reduce Nrelated environmental problems such as eutrophication, acidification or global warming. Nitrogenius was developed in the year 2000. This four-player computer ''game'' focuses on the Dutch N problems caused by N 2 O, NH 3 and NO x emissions as well as nitrate in surface and ground water. Underlying the glossy user interface is a set of comprehensive models and a database with potential measures that were considered to be feasible at the time. Since 2000, the model has been used for educational purposes annually at Wageningen University. About 150 MSc students played the game, with the aim to solve the N-related problems in the Netherlands. This article analyses these games, and presents the surprising correlation for the period 2000-2007 with the actual environmental trends in the Netherlands. The second tool is an N-visualisation tool that was developed in 2007. This tool provides both a historic overview of the nitrogen issue and demonstrates the effect of seven potential measures on the world wide N cycle. The effects of increased biomass use and intensification of agriculture are examples of included measures. The net effect on global warming, food availability and biodiversity are output parameters of this instrument. The calculations and assumptions underlying this tool are easily accessible through an open source spreadsheet. This tool was used in 2008 and 2009 at Wageningen University for educational purposes. The pros and cons of both games for awareness raising and educational purposes will be discussed.
In the marine atmosphere, small ions are produced mainly by cosmic radiation. The production rate... more In the marine atmosphere, small ions are produced mainly by cosmic radiation. The production rate q of small ion pairs at sea level is modulated in time by the 11-year sunspot cycle. Cosmic radiation is deflected in the magnetosphere by Lorentz forces and, consequently, q is also modulated with respect to geomagnetic latitude. Comparing empirical values of q, observed on different locations at different times, only makes sense when both the solar and the latitude modulations are accounted for. A review of the literature on cosmic radiation at sea level has resulted in a most probable parameterization of both of these modulations in the present study. 1.
This paper addresses two hypothesis that try to explain the difference observed between the estim... more This paper addresses two hypothesis that try to explain the difference observed between the estimated NH 3 emission levels in The Netherlands and those indicated by atmospheric measurements, the so called 'ammonia gap': the role of SO 2 emissions regulating ambient NH 3 concentrations through co-deposition, and long-term NH 3 emissions after slurry injection. It was found that throughfall measurements of NH 4 + could not be used as indicator for changes in NH 3 emissions. The throughfall deposition of NH 4 + is in close equilibrium to SO 4 2 − and NO 3 − and is thus regulated by the equilibrium of ambient NH 3 and NH 4 + in wet deposition and canopy water layers. When SO 2 emissions decrease, the amount of available SO 4 2 − decreases, which imposes a limit on the deposition of (NH 4) 2 SO 4. Long-term emissions of NH 3 after application of manure were monitored using a new technique, which continuously measures the concentration of NH 3 in a cross-section of the emission plume downwind of the source. The emissions could be registered for 3 weeks after application of manure. The results indicate that the long-term emissions only contribute 1-2% to the total emission level. Both the effect of SO 2 on the NH 3 deposition levels and the long-term emission fluxes are not enough to explain the observed ammonia gap. It seems that several counteracting effects, some of them emerging from the new emission reduction regulations, contribute to the ammonia gap. An integrated approach to abate ammonia emissions is, therefore, needed. The implementation and regulation of production ceilings for reactive nitrogen might be a good option.
Methane emissions of large parts of NW-Europe are derived from continuous concentration measureme... more Methane emissions of large parts of NW-Europe are derived from continuous concentration measurements at one sample site (Cabauw tower, The Netherlands) using the COMET transport model. This approach can be used as an independent check of emission estimates based on statistical information. COMET is a two-layer Lagrangian atmospheric transport model that describes the uptake of methane emissions in the mixing layer along a backward trajectory path and the exchange with a reservoir layer during mixing layer height changes. In inverse mode a Singular Value Decomposition (SVD) matrix inversion technique is used to calculate the emissions of a limited number of source areas using four years of 6-hourly concentration data (1993±1996) at Cabauw. The calculated emissions compare well with the current emission inventory data for the Netherlands and the surrounding countries. For the Netherlands a yearly emission of 757 Gg of methane is calculated, excluding the emissions from oil and gas mining at the North Sea continental shelf.
In-canopy turbulence is a required input to study pollutant cycling and chemistry within plant ca... more In-canopy turbulence is a required input to study pollutant cycling and chemistry within plant canopies and to link concentrations and sources. Despite the importance of grasslands worldwide, most previous work has focused on forests and crops. Here, turbulence parameters in a mature agricultural grassland canopy were measured with a combination of a small ultrasonic anemometer, hotwire anemometry and a radon (Rn) tracer technique, as part of a measurement to study ammonia (NH 3) exchange with grassland. The measurements are used to derive vertical profiles of basic turbulent parameters, for quadrant-hole analysis of the two-parametric frequency distributions of u-w and to derive in-canopy eddy diffusivities as input for models of incanopy tracer transport. The results are in line with previous measurements on taller canopies, but shows increased decoupling between in-canopy flow and above-canopy turbulence. The comparison of sonic anemometry and Rn measurements implies that Lagrangian timescales must decrease sharply at the ground, with important implications for estimating the magnitude of ground-level and soil emissions from concentration measurements. Atmospheric stability above and within the canopy has little influence on the standard deviation of vertical wind component inside the canopy. Use of the turbulence parameters in an analytical Lagrangian frame
Commonly, the micrometeorological parameters that underline the calculations of surface atmospher... more Commonly, the micrometeorological parameters that underline the calculations of surface atmosphere exchange fluxes (e.g. friction velocity and sensible heat flux) and parameters used to model exchange fluxes with SVATtype parameterisations (e.g. latent heat flux and canopy temperature) are measured with a single set of instrumentation and are analysed with a single methodology. This paper evaluates uncertainties in these measurements with a single instrument, by comparing the independent results from nine different institutes during the international GRAMINAE integrated field experiment over agricultural grassland near Braunschweig, Lower Saxony, Germany. The paper discusses uncertainties in measuring friction velocity, sensible and latent heat fluxes, canopy temperature and investigates the energy balance closure at this site. Although individual 15-min flux calculations show a large variability between the instruments, when averaged over the campaign, fluxes agree within 2% for momentum and 11% for sensible heat. However, the spread in estimates of latent heat flux (λE) is
Improved data on biosphere-atmosphere exchange are fundamental to understanding the production an... more Improved data on biosphere-atmosphere exchange are fundamental to understanding the production and fate of ammonia (NH 3) in the atmosphere. The GRAMINAE Integrated Experiment combined novel measurement and modelling approaches to provide the most comprehensive analysis of the interactions to date. Major intercomparisons of micrometeorological parameters and NH 3 flux measurements using the aerodynamic gradient method and relaxed eddy accumulation (REA) were conducted. These showed close agreement, though the REA systems proved insufficiently precise to investigate vertical flux
During recent years, it has become clear that ammonia is an important gas in relation to di!erent... more During recent years, it has become clear that ammonia is an important gas in relation to di!erent environmental issues, such as acidi"cation, eutrophication, human health and climate change (through particle formation). Therefore, there is a growing need to develop and apply instrumentation suitable for research into emission, dispersion, conversion and deposition of ammonia and ammonium. Recently, several instruments were developed suitable for measuring concentrations in ambient conditions even at very low levels, such as ammonia sensors suitable for monitoring and research, deposition measuring systems and aerosol samplers for on-line measurement of aerosol composition. These instruments have been tested and applied in a number of "eld studies. These studies include dry deposition measurements, ammonium nitrate studies in relation to the (in)direct aerosol e!ect, emission studies and policy evaluation with concentration and deposition monitoring data. The policy evaluation study showed that the measures to reduce ammonia emissions were not as successful as projected beforehand by statistical studies.
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