An assessment of the potential for atmospheric emission verification in The Netherlands

Doel van dit project was het ontwikkelen van een systeem voor het kwantificeren van het broeikasgasbudget op landelijke en regionale schaal. Het ME2 consortium heeft een ‘protocol’ ontwikkeld om een referentieschatting te maken ten behoeve van de verificatie van nationale emissies. Daarmee is het op termijn mogelijk de nauwkeurigheid en geloofwaardigheid van aan UNFCCC en Kyoto gerapporteerde emissies, en reducties daarvan, te verifiëren. Met verschillende inversie methoden, van data tot model gedreven, zijn emissieschattingen gemaakt. De data gedreven methoden kunnen schattingen maken voor alle drie de broeikasgassen voor NL als geheel en zijn representatief voor meerdere jaren. Met de meer model gedreven inversies zijn meer ruimtelijk en temporeel gedistribueerde schattingen te maken

Cross contamination in dual inlet isotope ratio mass spectrometers

Since the early days of geochemical isotope ratio mass spectrometry there has always been the problem of cross contamination, i.e. the contamination of the sample gas with traces of reference gas (and vice versa) in a dual inlet system and the analyzer itself. This was attributable to valve leakages and could be corrected for. In modern leak-free machines this problem still influences the measurements by scale contraction. It limits the interlaboratory comparability to values unacceptable for, e.g. global carbon cycle investigations on atmospheric δ13CO2, with the need to integrate global datasets at a 0.01‰ precision level. No matter what the reason of apparent cross contamination (physical leakage, low pump efficiency, gas–wall interactions), we present a method to measure the actual cross contamination as well as algorithms to correct for it. By using isotopically enriched sample gas the effect on the reference gas is directly shown. Especially for biomedical applications, employing highly enriched materials, the nonlinear correction has to be applied. A long-time record of two machines shows the influence of vacuum breakage and the inlet system setup. We present a survey of cross contamination in some of the frequently used machines. The relatively poor raw results of two recent interlaboratory comparison experiments are explained in terms of cross contamination. Whereas the linear two-point normalization procedure considered by itself may be appropriate for some routine applications at natural isotope abundances, it always relies on relative δ values of two reference materials. There is an urgent need to establish absolute values for all scale-determining reference materials. We recommend the use of cross contamination measurements to at least determine the isotopic composition of all normalization materials as long as absolute measurements are not available. In principle, the cross contamination measurements should be used as a diagnostic tool on a regular basis.

Atmospheric oxygen and carbon dioxide observations from two European coastal stations 2000–2005: continental influence, trend changes and APO climatology

Seeking for baseline conditions has biased the atmospheric carbon dioxide (CO2) and later on also oxygen (O2) monitoring networks towards remote marine stations, missing part of the variability that is due to regional anthropogenic as well as land biotic activity. We present here a five-year record of atmospheric CO2 concentrations and oxygen/nitrogen (O2/N2) ratio measurements from the coastal stations Lutjewad (LUT), The Netherlands and Mace Head (MHD), Ireland, derived from flask samples. O2/N2 ratios, a proxy for O2 concentrations, concurrently measured with CO2 concentrations, help determine regional CO2 fluxes by separating land fluxes from sea fluxes. Mace Head is the closest marine baseline station to Lutjewad, located at the same latitude, and therefore is taken as a reference. During the studied period, from 2000 until 2005, we observed an average increase of CO2 in the atmosphere of (1.7±0.2) ppm y−1, and a change of the O2/N2 ratio of (−20±1) per meg y−1. The difference between the CO2 summer minimum and the winter maximum is 14.4 ppm and 16.1 ppm at Mace Head and Lutjewad, respectively, while the paraphase variation in the O2 signal equals 113 per meg and 153 per meg, respectively. We also studied the atmospheric potential oxygen (APO) tracer at both stations. By this analysis, evidence has been found that we need to be careful when using APO close to anthropogenic CO2 sources. It could be biased by combustion-derived CO2, and models need to take into account daily and seasonal variations in the anthropogenic CO2 production in order to be able to simulate APO over the continents.

Methane and nitrous oxide emissions in The Netherlands: ambient measurements support the national inventories

We present net emission estimates of CH4 and N2O of The Netherlands based on measurements conducted during the period of May 2006 to April 2009 at station Lutjewad, The Netherlands (6°21' E, 53°24' N, 1 m a.s.l.). 222Radon mixing ratios were applied as an indicator for vertical mixing and long-range air mass transport and used to calculate the net surface fluxes from atmospheric mixing ratios of CH4 and N2O. Our study shows that our measurement site Lutjewad is well-suited to measure emissions from The Netherlands and validation of the national inventories using the 222Radon flux method. Since this study is purely observation-based it is independent from inventories or atmospheric models. Our results are compared to the national inventories as reported to the UNFCCC. We found net emissions of: (15.2±5.3) t km−2 a−1 for CH4 and (0.9±0.3) t km−2 a−1 for N2O. These values are lower than the inventory-based emissions (2006-2008 averages) of (18.3±3.3) t km−2 a−1 for CH4, and (1.3±0.6) t km−2 a−1 for N2O, but the differences are insignificant.