Aquifer breathing: how a rising water table controls nitrogen transport

Shallow aquifers experience water table fluctuations, which we term “aquifer breathing” as they push and pull air through the vadose zone, affecting redox state site (full study: https://doi.org/10.1007/s10040-026-03068-5). We investigated the fate of nitrogen at a meter-long column with soil and aquifer materials from a forested mountain stream We used local groundwater to create water level fluctuations. The organic topsoil remained aerobic, acting as nitrate source, when dry, but switched to reducing conditions, favoring denitrification, when saturated. Flooding with river water flushed accumulated nitrate toward the aquifer. The experiment captures the wide span of redox conditions that develop in floodplains that turn the soils into nitrate sinks or sources as the water table rises and falls.

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