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The fuel sulfur content (FSC) of ocean-going and inland vessels was measured simultaneously by eight different state-of-the-art and novel monitoring systems during a 6-week campaign at the Elbe River, at a distance of about 10 km to the port of Hamburg, Germany. Both stationary and airborne systems on unoccupied aerial vehicles (UAVs) were operated by four participating partners in a side-by-side measurement setup to measure the emission factors of the same emission sources. A novel laser spectrometer, with significantly better-precision specifications as compared with the other instruments, was used for the first time for emission monitoring regarding the International Convention for the Prevention of Pollution from Ships (MARPOL) Annex VI regulations. The comparison took place in the North Sea sulfur emission control area (SECA), where the allowed FSC is limited to 0.10 %Sm/m. The unit %Sm/m relates to the percentage of mass sulfur per mass combusted fuel. In total, 966 plumes that originated from 436 different vessels were analysed in this study. At the same time, fuel samples obtained from 34 different vessels and bunker delivery notes (BDNs) from five frequently monitored vessels were used as a reference to assess the uncertainties of the different systems. Seven of the eight measurement systems tended to underestimate the FSC found from fuel samples and BDNs. A possible relation between underestimation and high relative humidities (above 80 %) was observed. The lowest systematic deviations were observed for the airborne systems and the novel laser spectrometer. The two UAV-borne systems showed total uncertainties of 0.07 %Sm/m and 0.09 %Sm/m (confidence level: 95 %). The novel laser spectrometer showed the lowest total uncertainty of 0.05 %Sm/m compared with other stationary sniffer systems, whose total uncertainties range from 0.08 %Sm/m to 0.09 %Sm/m. It was concluded that non-compliant vessels, with an actual FSC of the combusted fuel above 0.15 %Sm/m to 0.19 %Sm/m, can be detected by the compared systems with 95 % confidence.

Methods for the determination of ship fuel sulphur content and NOx emission factors based on remote measurements have been compared in the harbour of Rotterdam and compared to direct stack emission measurements on the ferry Stena Hollandica. The methods were selected based on a review of the available literature on ship emission measurements. They were either optical (LIDAR, Differential Optical Absorption Spectroscopy (DOAS), UV camera), combined with model-based estimates of fuel consumption, or based on the so called "sniffer" principle, where SO2 or NOx emission factors are determined from simultaneous measurement of the increase of CO2 and SO2 or NOx concentrations in the plume of the ship compared to the background. The measurements were performed from stations at land, from a boat and from a helicopter. Mobile measurement platforms were found to have important advantages compared to the land-based ones because they allow optimizing the sampling conditions and sampling from ships on the open sea. Although optical methods can provide reliable results it was found that at the state of the art level, the "sniffer" approach is the most convenient technique for determining both SO2 and NOx emission factors remotely. The average random error on the determination of SO2 emission factors comparing two identical instrumental set-ups was 6%. However, it was found that apparently minor differences in the instrumental characteristics, such as response time, could cause significant differences between the emission factors determined. Direct stack measurements showed that about 14% of the fuel sulphur content was not emitted as SO2. This was supported by the remote measurements and is in agreement with the results of other field studies.

The chemical composition of the plumes of seagoing ships was measured during a two week long measurement campaign in the port of Rotterdam, Hoek van Holland The Netherlands, in September 2009. Altogether, 497 ships were monitored and a statistical evaluation of emission factors (g kg−1 fuel) was provided. The concerned main atmospheric components were SO2, NO2, NOx and the aerosol particle number. In addition, the elemental and water-soluble ionic composition of the emitted particulate matter was determined. Emission factors were expressed as a function of ship type, power and crankshaft rotational speed. The average SO2 emission factor was found to be roughly half of what is allowed in sulphur emission control areas (16 vs. 30 g kg−1 fuel), and exceedances of this limit were rarely registered. A significant linear relationship was observed between the SO2 and particle number emission factors. The intercept of the regression line, 4.8 × 1015 (kg fuel)−1, gives the average number of particles formed during the burning of 1 kg zero sulphur content fuel, while the slope, 2 × 1018, provides the average number of particles formed with 1 kg sulphur burnt with the fuel. Water-soluble ionic composition analysis of the aerosol samples from the plumes showed that ~144 g of particulate sulphate was emitted from 1 kg sulphur burnt with the fuel. The mass median diameter of sulphate particles estimated from the measurements was ~42 nm.

Soil emissions of NO and N2O were measured continuously at high frequency for more than one year at 15 European forest sites as part of the EU-funded project NOFRETETE. The locations represent different forest types (coniferous/deciduous) and different nitrogen loads. Geographically they range from Finland in the north to Italy in the south and from Hungary in the east to Scotland in the west. The highest NO emissions were observed from coniferous forests, whereas the lowest NO emissions were observed from deciduous forests. The NO emissions from coniferous forests were highly correlated with N-deposition. The site with the highest average annual emission (82 μg NO-N m−2 h−1) was a spruce forest in South-Germany (Höglwald) receiving an annual N-deposition of 2.9 g m−2. NO emissions close to the detection limit were observed from a pine forest in Finland where the N-deposition was 0.2 g N m−2 a−1. No significant correlation between N2O emission and N-deposition was found. The highest average annual N2O emission (20 μg N2O-N m−2 h−1) was found in an oak forest in the Mátra mountains (Hungary) receiving an annual N-deposition of 1.6 g m−2. N2O emission was significantly negatively correlated with the C/N ratio. The difference in N-oxide emissions from soils of coniferous and deciduous forests may partly be explained by differences in N-deposition rates and partly by differences in characteristics of the litter layer and soil. NO was mainly derived from nitrification whereas N2O was mainly derived from denitrification. In general, soil moisture is lower at coniferous sites (at least during spring time) and the litter layer of coniferous forests is thick and well aerated favouring nitrification and thus release of NO. Conversely, the higher rates of denitrification in deciduous forests due to a compact and moist litter layer lead to N2O production and NO consumption in the soil. The two factors soil moisture and soil temperature are often explaining most of the temporal variation within a site. When comparing annual emissions on a regional scale, however, factors such as nitrogen deposition and forest and soil type become much more important.

Forest soils are a significant source for the primary and secondary greenhouse gases N2O and NO. However, current estimates are still uncertain due to the still limited number of field measurements and the herein observed pronounced variability of N trace gas fluxes in space and time, which are due to the variation of environmental factors such as soil and vegetation properties or meteorological conditions. To overcome these problems we further developed a process-oriented model, the PnET-N-DNDC model, which simulates the N trace gas exchange on the basis of the processes involved in production, consumption and emission of N trace gases. This model was validated against field observations of N trace gas fluxes from 19 sites obtained within the EU project NOFRETETE, and shown to perform well for N2O (r2=0.68, slope=0.76) and NO (r2=0.78, slope=0.73). For the calculation of a European-wide emission inventory we linked the model to a detailed, regionally and temporally resolved database, comprising climatic properties (daily resolution), and soil parameters, and information on forest areas and types for the years 1990, 1995 and 2000. Our calculations show that N trace gas fluxes from forest soils may vary substantial from year to year and that distinct regional patterns can be observed. Our central estimate of NO emissions from forest soils in the EU amounts to 98.4, 84.9 and 99.2 kt N yr−1, using meteorology from 1990, 1995 and year 2000, respectively. This is x emissions. For N2O emissions the central estimates were 86.8, 77.6 and 81.6 kt N yr−1, respectively, which is approx. 14.5% of the source strength coming from agricultural soils. An extensive sensitivity analysis was conducted which showed a range in emissions from 44.4 to 254.0 kt N yr−1 for NO and 50.7 to 96.9 kt N yr−1 for N2O, for year 2000 meteorology. The results show that process-oriented models coupled to a GIS are useful tools for the calculation of regional, national, or global inventories of biogenic N trace gas emissions from soils. This work represents the most comprehensive effort to date to simulate NO and N2O emissions from European forest soils.

Simulation of emissions of the greenhouse gas N2O from agricultural land is still a challenge. This is mainly due to its high temporal variability, with low background emissions and a few transient peaks. In this study, a first attempt was made to simulate observations of N2O fluxes with a daily time step from managed peat soils. We used a new N2O module added to the extensively tested hydrological-biogeochemical model combination SWAP-ANIMO, hypothesizing that accurate simulation of the controlling factors would imply accurate simulation of the dynamics of the N2O emissions as well. We used daily N2O emission data from three sites in the Netherlands, with complementary data on soil moisture, mineral N content, and soil N2O concentration. Simulation of soil moisture, mineral N, and N2O concentration was reasonable to good. Still, simulation of the daily N2O emissions was poor, with model efficiencies <0, mainly due to overestimation of N2O emission from denitrification in the topsoil. We expect that the model overestimated diffusion of N2O from the topsoil to the atmosphere, thereby underestimating further reductions of N2O to N2 This was probably linked to the complex peat pore geometry. We concluded that the description of the N2O processes in our model was insufficient to accurately simulate daily N2O emissions from peat soils, even when the main controlling factors are accurately simulated. Improvement is expected from incorporation of the effects of (peat) pore geometry on soil moisture and consequently on N2O production, reduction, storage, and transport. [ABSTRACT FROM AUTHOR]