The amount and timing of reactive nitrogen exchange between agricultural land and the atmosphere play a key role in evaluating ecosystem productivity and in addressing atmospheric nitrogen budgets and transport. With the recent development of the Total Reactive Atmospheric Nitrogen Converter (TRANC) apparatus, a methodology has been provided for continuous measurement of the sum of all airborne nitrogen containing species (ΣNr) allowing for diurnal and seasonal investigations. We present ΣNr concentration and net flux data from an 11-month field campaign conducted at an arable field using the TRANC system within an eddy-covariance setup. Clear diurnal patterns of both ΣNr concentrations and fluxes with significant dependencies on atmospheric stability and stomatal regulation were observed in the growing season. TRANC data were compared with monthly-averaged concentrations and dry deposition rates of selected Nr compounds using DELTA denuders and ensemble-averages of four inferential models, respectively. Similar seasonal trends were found for Nr concentrations from DELTA and TRANC measurements with values from the latter being considerably higher than those of DELTA denuders. The variability of the difference between these two systems could be explained by seasonally changing source locations of NOx contributions to the TRANC signal. As soil and vegetation Nr emissions to the atmosphere are generally not treated by inferential (dry deposition) models, TRANC data showed lower monthly deposition rates than those obtained from inferential modelling. Net ΣNr exchange was almost neutral (~0.072 kg N ha−1) at the end of the observation period. However, during most parts of the year, slight but permanent net ΣNr deposition was found. Our measurements demonstrate that fertilizer addition followed by substantial ΣNr emissions plays a crucial role in a site's annual atmospheric nitrogen budget. As long-term Nr measurements with high temporal resolution are usually cost and labour-intensive, field application of the TRANC helps improve the understanding of ecosystem functioning, atmospheric transport and revising definitions of ecosystem-specific critical loads at a relatively moderate operational cost level
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.
Abstract. The input and loss of plant available nitrogen (reactive nitrogen: N r ) from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter), which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds ( N r ) in high time resolution. The basic concept of the TRANC is the full conversion of all N r to nitrogen monoxide (NO) within two reaction steps. Initially, reduced N r compounds are being oxidised, and oxidised N r compounds are thermally converted to lower oxidation states. Particulate N r is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD) for NO analysis and its performance was tested for the most relevant gaseous and particulate N r species under both laboratory and field conditions. Recovery rates during laboratory tests for NH 3 and NO 2 were found to be 95 and 99 %, respectively, and 97 % when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91 % for NO 2 . Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient N r was tested against the sum of individual measurements of NH 3 , HNO 3 , HONO, NH + 4 , NO − 3 , and NO x using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in N r concentrations and also matches the sum of all individual N r compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (e-folding times of 0.30 to 0.35 s were found during concentration step changes) and high accuracy in capturing the dominant N r species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific N r compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net N r flux between ecosystem and atmosphere at a relatively low maintenance and reasonable cost level allowing for diurnal, seasonal and annual investigations.
We assessed long-term effects of cardiac contractility modulation delivered by the Optimizer Smart system on quality of life, left ventricular ejection fraction (LVEF), mortality and heart failure and cardiovascular hospitalizations.
The input and loss of plant available nitrogen (N) from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for the measurement of total reactive nitrogen (TRANC: <B>T</B>otal <B>R</B>eactive <B>A</B>tmospheric <B>N</B>itrogen <B>C</B>onverter), which offers the opportunity to quantify the sum of all airborne reactive nitrogen (N<sub>r</sub>) compounds in high time resolution. The basic concept of the TRANC is the full conversion of total N<sub>r</sub> to nitrogen monoxide (NO) within two reaction steps. Initially, reduced N compounds are being oxidised, and oxidised N compounds are thermally converted to lower oxidation states. Particulate N is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher N oxides or those originated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD) for NO analysis and its performance was tested for the most relevant gaseous and particulate N<sub>r</sub> species under both laboratory and field conditions. Recovery rates during laboratory tests for NH<sub>3</sub> and NO<sub>2</sub> were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO<sub>2</sub>. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient N<sub>r</sub> was tested against the sum of individual measurements of NH<sub>3</sub>, HNO<sub>3</sub>, HONO, NH<sub>4</sub><sup>+</sup>, NO<sub>3</sub><sup>−</sup>, and NO<sub>x</sub> using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in N<sub>r</sub> concentrations and also matches the sum of all N<sub>r</sub> compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal and catalytic conversions to NO occur. This assures a short residence time of the sample air inside the instrument, and minimises wall sorption problems of water soluble compounds. The fast response time (half-value periods of 0.30 s were found during concentration step changes) and high accuracy in capturing the dominant N<sub>r</sub> species enables the converter to be used in an eddy covariance setup. Although a source attribution of specific N<sub>r</sub> compounds is not possible, the TRANC is a new reliable tool for permanent measurements of the net N<sub>r</sub> flux between ecosyst...
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