Gridded dataset of nitrogen and phosphorus point sources from wastewater in Germany (1950–2019)

Abstract. Knowledge about the long history of the anthropogenic inputs of nitrogen (N) and phosphorus (P) is crucial to capture long-term N and P processes (legacies) and to investigate water quality and ecosystem health. These inputs include N and P point sources, which mainly originate from wastewater and which are directly discharged into surface waters, thus having an immediate impact on ecosystem functioning. However, N and P point sources are challenging to estimate, due to the scarcity of and uncertainty in observational data. Here, we contribute towards improved characterisation of N and P point sources from wastewater by providing a long-term (1950–2019), high-resolution (0.015625° ≈1.4 km on average) dataset for Germany. The dataset includes both domestic and industrial emissions treated in wastewater treatment plants and untreated domestic emissions that are collected in the sewer system. We adopt a modelling approach that relies on a large range of data collected from different sources. Importantly, we account for the uncertainties arising from different modelling choices (i.e. coefficients and downscaling approach). We provide 200 gridded N and P point source realisations, which are constrained and evaluated using available (recent) observations of wastewater treatment plants' outgoing loads. We discuss the uncertainties in our reconstructed dataset over a large sample of river basins in Germany and provide guidance for future uses. Overall, by capturing the long-term spatial and temporal variations in N and P point sources and accounting for uncertainties, our dataset can facilitate long-term and large-scale robust water quality studies. The dataset is available at https://doi.org/10.5281/zenodo.10500535 (Sarrazin et al., 2024).