In a citizen science project, volunteers analysed nitrogen pollution in water bodies. The team presented the results yesterday.
The 800 participants in a citizen science project coordinated by the universities of Oldenburg and Osnabrück collected exactly 8,754 water samples from September 2019 to March 2021. At more than 540 locations in the districts of Osnabrück, Vechta, Emsland and Cloppenburg as well as the city of Osnabrück, the volunteers used special test strips to examine well water, spring water, running water, standing water and rainwater in order to get an overview of the nitrate content based on colour shades.
The project team reported at an event at the Catholic Academy Stapelfeld in Cloppenburg that a large proportion of the watercourses sampled showed excessive nitrate levels. The scientists from the University of Osnabrück categorised three quarters of the watercourses sampled as highly or very highly polluted, confirming the results of previous studies.
"High nitrate pollution is a concern for both aquatic ecology and human health," says Melanie Vogelpohl, advisor for environmental information at the German Federal Environmental Foundation (DBU). "The issue has become more prominent thanks to the high level of citizen involvement."
Citizens make an important contribution
The foundation-funded project focussed on the citizen science approach: the researchers involved citizens in scientific research. "The results show that volunteers can make an important contribution to research into water protection," emphasised Prof. Dr Marco Beeken from the University of Osnabrück. The chemistry didactics expert led the project together with Prof Dr Verena Pietzner - a chemistry didactics expert at the University of Oldenburg until the end of last year and now President of the University of Vechta. The approach of involving volunteers has proved successful, emphasised Pietzner: "The high number of 800 participants shows that there is a great deal of interest in environmental topics in the region."
Within the project, interested parties were not only able to contribute measured values, but also take advantage of other offers such as school labs, an online exhibition or a nitrogen box with experiments designed by the University of Oldenburg to gain insights into the topic of nitrogen pollution. In an accompanying study, Osnabrück University is currently investigating the extent to which participation in the Citizen Science project changes attitudes and knowledge on the subject of water pollution control.
Great commitment
Among the volunteers involved in the project were 200 pupils and their teachers. "Without the great commitment and so many participants, we would not have been able to collect this amount of data or carry out the project so successfully," says research assistant Mientje Lüsse from the University of Oldenburg. The citizen science approach can play an innovative role in scientific research and at the same time impart education.
The measurement results showed a high level of agreement with the results of other measurement initiatives such as the well water measurements of the VSR-Gewässerschutz environmental organisation. Beeken was satisfied with the quality of the results: "The test strips used are reliable enough to gain an overview of the nitrate pollution and to track spatial and temporal developments. We are currently developing a measurement method with a colour sensor and elements from the 3D printer in order to carry out more precise measurements at the end of projects."
High pollution levels, especially in flowing waters
The team used the data to analyse which factors influence nitrate pollution. "The measurements taken by citizens show that narrow streams such as the Bornbach near Damme are particularly at risk, as even a low nitrate input leads to high concentrations," explains project team member and doctoral student Frauke Brockhage from the University of Osnabrück. According to the analysis, stagnant waters such as lakes are less polluted than flowing waters, but even here almost a quarter of the measuring points showed high or very high nitrate levels. Of the wells sampled, around one sixth exceeded the legal limit of 50 milligrams per litre. According to the analysis, the composition of the soil in particular plays a major role in groundwater pollution: particularly high nitrate concentrations were found in geest areas with sandy soils.
According to Brockhage, the nitrate contamination of the watercourses sampled is higher in urban and agricultural areas than in forests and near-natural areas. However, the researchers are unable to make any statements about the specific causes of this based on the data. It is known that agricultural fertilisers are a major source of nitrate in water bodies. However, industry, transport and wastewater also contribute to pollution. High nitrate levels lead to over-fertilisation of water bodies with algae blooms and oxygen deficiency and increase the costs of drinking water production and treatment. In follow-up projects, the team wants to investigate the causes in more detail.
The project was supported by an advisory board, which included representatives from the Lower Saxony Water Management, Coastal Defence and Nature Conservation Agency (NLWKN) and the Cloppenburg District Farmers' Association.
