The UCD expert behind a new gassy test for water quality

Dr. Alan Seltzer, a hydrogeology expert at University College Dublin (UCD), has co-authored a paper proposing a novel method for testing water quality using a rare form of nitrogen gas. The quantity of nitrogen in water is a crucial indicator of its quality, with excessive concentrations leading to harmful algal blooms that can cause aquatic life to die. Microbes in water can mitigate nitrogen levels by converting it into gas, but determining the extent of this removal has been a challenge for researchers.

Seltzer's study, published in the journal Science, highlights that a rare isotopologue of nitrogen gas known as 15N15N acts as a natural fingerprint for microbial nitrogen conversion. With over a decade of experience specializing in water geochemistry, Seltzer's research is rooted in the study of dissolved noble gases, which are chemically unreactive and serve as natural tracers to reconstruct the history of groundwater and the oceans.

Currently based at UCD's School of Earth Sciences since 2025, Seltzer has a PhD in Earth Science from the University of California San Diego and previously worked at Woods Hole Oceanographic Institution as a postdoctoral researcher. His work aims to build upon existing techniques and apply them in innovative ways to enhance understanding of nitrogen contamination in groundwater and the natural processes that can help remove it.

Seltzer's recent European Research Council (ERC) Starting Grant, Tracing Anthropogenic Biogeochemical and Physical Influences on Subsurface Hydrogeology (TABPHISH), combines laboratory-based geochemical tracer development with field-based research across six global study areas. This project targets a significant challenge in groundwater science: determining the original amount and source of nitrate in groundwater systems, particularly when microbial consumption of nitrate results in the conversion of nitrate into nitrogen gas.

Groundwater is a vital source of drinking water for billions of people and a primary water source for agriculture and industry worldwide. In Ireland, nitrogen pollution poses a significant environmental challenge, with crucial implications for water quality and ecosystem health. Seltzer's research focuses on developing geochemical techniques to measure aspects of groundwater systems that are otherwise difficult to observe and has the potential to be applied globally, aiding in the understanding and management of critical water resources.

Seltzer believes that recent geopolitical events haven't fundamentally altered his perspective on the importance of his research. He emphasizes that science's underlying objectivity, achieved through careful experimentation, analysis, and statistical treatment, allows for answers grounded in scientific merit, independent of political considerations.

While research funding, international collaborations, and the use of scientific findings can be influenced by politics, Seltzer remains committed to rigorous scientific inquiry to inform responsible interaction with the natural world.