The aim of the ArNO groundwater project is to test and evaluate methods used to assess nitrate pollution in groundwater. To this end, literature research as well as practical investigations in the field and laboratory are carried out.
At the second project meeting of "ArNO groundwater project: Nitrate contamination of catchment areas - Suitability of used groundwater measuring points for determining nitrate contamination, with consideration of historical nitrate inputs", the current status of the research and the first project results were presented and discussed with the project advisory group on 19 February 2025. The project (funding code 02WGW1720) started on 1 March 2024 and will run for two years. It is funded by the German Federal Ministry of Education and Research (BMBF) as part of the federal programme "Water: N". Water: N is part of the BMBF's "Research for Sustainability" (FONA) strategy.
The scientists are particularly focussed on determining minimum requirements for groundwater measuring points to determine the nitrate concentration in groundwater and to quantify nitrate degradation in groundwater. Although nitrate degradation only occurs in groundwater under certain conditions, it makes it difficult to determine the original nitrate inputs, for example from agriculture. For this purpose, the so-called nitrogen/argon method (N2/Ar method) is used in the project. The project acronym "ArNO" is derived from this method and from the sum formula of nitrate (NO3-).
The research work is carried out by TZW: DVGW-Technologiezentrum Wasser (German Water Centre) in Karlsruhe and Dresden (Germany). The project receives support from the environmental agencies of four federal states and two water supply companies as well as two engineering firms and the TU Bergakademie Freiberg, which together form the project advisory group. The project advisory group provides counselling to the researchers of the ArNO project, discusses the research results with them at project meetings and helps to accelerate the implementation of the findings in practice. The project advisory group furthermore supports the project by providing access to groundwater measuring points and making analysis data or samples available to the researchers.
Method evaluation on the basis of scientific, practical investigations
According to the current nitrate report from 2024, 26% of the total of approx. 13,500 measuring points in the nationwide measuring network for designating nitrate vulnerable zones exceed the nitrate limit of 50 mg nitrate per litre and consequently have a poor chemical status in accordance with the EU Water Framework Directive (as of 2022). As the leaching of nitrogenous fertilisers is a major source of nitrate entering the groundwater, strict regulations apply to agriculture in nitrate-polluted, so-called "red areas". The red areas designated are sometimes difficult for farmers and water suppliers to retrace, which is why the underlying measuring points and methods are in part being questioned. The ArNO groundwater project aims to achieve the following work objectives through technical, practical analyses:
- Development of minimum requirements for groundwater measuring points for analysing nitrate pollution.
- Development of a decision aid for the selection of a suitable interpolation method in order to obtain representative area information from nitrate values measured at various points.
- Determination of the requirements for sampling to determine the nitrate input masked by nitrate degradation.
- Increasing process and system understanding of nitrate degradation in groundwater through extensive field investigations.
Further information is available here on the ArNO project site
