Hydrological control on groundwater electrical conductivity, pH, dissolved oxygen and oxidation reduction potential in a forested Critical Zone observatory: the Weierbach Experimental Catchment, Luxembourg.

The critical zone (CZ) serves as the Earth's skin where rock, water, air, and life interact, playing a pivotal role in sustaining ecological processes and life-supporting resources. Understanding these interactions, especially in forested headwater catchments, is crucial for managing water resources, predicting environmental responses, and assessing human impacts. This study presents a novel dataset from the Weierbach Experimental Catchment in Luxembourg, derived from a year-long high-frequency monitoring campaign focused on groundwater physico-chemical parameters. Through meticulous data collection and rigorous quality control, additional physicochemical parameters such as electrical conductivity (EC), dissolved oxygen (DO), oxidation-reduction potential (ORP), and pH were measured to complement the chemical suite already analyzed (major cations and anions), offering new insights into the CZ's hydrological and biogeochemical dynamics.The results highlight the intricate interplay between redox reactions, pH, and ion exchange processes, as well as the influence of seasonal variability on solute transport within the catchment. By providing a detailed view of the catchment's response to hydrological changes, we fill a significant gap in CZ research, offering a valuable resource for advancing our understanding of hydro-biogeochemical catchment processes. This contribution is not only a step forward in CZ science but also serves as a critical tool for researchers and practitioners aiming to refine models, inform land management practices, and foster a more holistic understanding of catchment biogeochemistry.