During her PhD studies, Sofie Gyritia Madsen van’t Veen investigated the application of high-frequency (HF) sensors for monitoring nutrients in Danish headwater streams. These sensors have the potential to revolutionize national nutrient monitoring by enabling frequent measurements, which can contribute to more accurate load estimates to coastal areas and lakes, and lower costs for the environment and society. Sofie Gyritia Madsen van’t Veen tested HF Nitratax and Solitax sensors (HACH, Düsseldorf, Germany) in Danish headwater streams, measuring NO3-N and turbidity. The SentemQC method was developed and tested as one step in a quality assurance and quality control (QA-QC) approach of sensor data to ensure reliable data.

Results showed that HF sensors can improve the accuracy of nutrient load estimates in streams, particularly monthly load estimates, which is crucial for future regulation, catchment management, and the Danish government’s “Grøn Trepart” agreement.

The PhD study was completed at Department of Ecoscience, Faculty of Technical Sciences, Aarhus University and Envidan A/S

This summary was prepared by the PhD student.

Time: Tuesday, April 1, 2025 at 12.30-15.30
Place: Building no. 1427/246, room no. M2, Aarhus University, Fredrik Nielsens Vej 4, 8000 Aarhus C
Title of PhD thesis: Sensor application for high temporal resolution monitoring in Danish headwater streams (SENTEM)
Contact information: Sofie Gyritia Madsen van’t Veen, e-mail: svv@ecos.au.dk / smv@envidan.dk, tel.: +45 28257578
Members of the assessment committee:
Development Director, PhD, Morten Lauge Fejerskov, NIRAS A/S, Denmark
Research scientist, UMR SAS Remi Dupas, French National Research Institute for Agriculture, Food and Environment (INRAE), France
Professor Christian Frølund Damgaard (chair), Department of Ecoscience, Aarhus University, Denmark
Main supervisor:
Professor Brian Kronvang, Department of Ecoscience, Aarhus University, Denmark
Co-supervisor:
Marketing Manager, Nature and Aquatic Environment, PhD, Esben Astrup Kristensen, Envidan A/S, Denmark
Team leader, Nature and Aquatic Environment, PhD, Jane Rosenstand Laugesen, Envidan A/S, Denmark
Language: The PhD dissertation will be defended in English

The defence is public.
The PhD thesis is available for reading at the Graduate School of Technical Sciences/GSTS, Ny Munkegade 120, building 1521, 8000 Aarhus C.