Abstract

For years, RIVM has been measuring various nitrogen compounds, including ammonia and nitrogen oxides. The concentrations of these substances are measured in the air together with the amount of nitrogen that is deposited on the soil via rain (wet deposition) and via the air (dry deposition). In the coming years, the number of measuring points will be expanded in order to reduce the uncertainties in the determination of the nitrogen deposition. This will make it possible to map the nitrogen deposition even more accurately.

This report explains the reasoning behind the choice of locations for the expansion. RIVM describes the goals of the measurements in general and of the expansion of the measuring points in particular. The four most important goals are: validating the models, monitoring developments over time, studying nitrogen related processes, and evaluating the quality of measurements. In addition, we describe the criteria for determining where the new measuring points will be located. In order to validate models, for example, the measuring points must be well distributed throughout the Netherlands and be representative of the spatial scale on which calculations are made.

This study is a first step in the expansion of the measurement network and contributes to a more detailed and refined measurement network. As a result of ongoing developments in scientific insights and techniques, RIVM will regularly revise the measurement strategy. Science develops further, for example, due to new measurement techniques evolving over time. Future research will focus on how the calculation of deposition can be improved with the help of measurements from satellites and sensors (from citizen science projects). In addition, the present scientific uncertainties could possibly be reduced by using multiple models. In each case, an assessment will be made as to which combination of model calculations and measurements can best be used for each individual nitrogen component.