Summary: Compound-specific isotope analysis (CSIA) is a powerful tool for investigating the sources, fate, and transformation of organic contaminants in environmental systems. By providing isotope information at the compound level, CSIA can help distinguish contaminant sources, identify degradation pathways, evaluate reaction mechanisms, and assess the performance of natural and engineered remediation processes. This session will focus on recent advances and applications of CSIA in environmental forensics, contaminant transformation, and remediation monitoring. Contributions are invited on chlorinated solvents, petroleum hydrocarbons, pesticides, industrial chemicals, emerging contaminants, and other organic compounds of environmental concern. Studies using carbon, hydrogen, chlorine, bromine, nitrogen, sulfur, or multi-element isotope approaches are welcome. Topics may include biodegradation, abiotic transformation, monitored natural attenuation, enhanced bioremediation, in situ chemical oxidation or reduction, thermal treatment, and treatment performance assessment. The session also welcomes methodological developments, low-concentration applications, inter-laboratory comparability, and integration of CSIA with concentration data, geochemistry, molecular biology, and reactive transport modelling. The goal of this session is to highlight how CSIA can provide direct evidence of contaminant transformation and support more reliable decisions in environmental assessment and remediation.

Summary: Reactive solute transport is a fundamental process controlling the movement, transformation, and fate of chemical components in subsurface and surface environments. From pore-scale mineral–fluid interactions to catchment-scale hydrogeological systems, solute migration is governed by complex coupling among physical transport processes, geochemical reactions, and biological activities. Advancing our understanding of reactive transport across multiple spatial and temporal scales is essential for predicting groundwater quality evolution, contaminant migration, nutrient cycling, resource formation, and environmental responses to natural and anthropogenic disturbances. However, scaling heterogeneous geological structures, reaction mechanisms, and coupled processes from laboratory observations to field-scale predictions remains a major scientific challenge.
This session welcomes contributions that investigate: (i) theoretical developments and conceptual frameworks for reactive solute transport across different scales; (ii) coupled processes involving advection, diffusion, dispersion, mineral reactions, sorption, precipitation, dissolution, and biogeochemical transformations; (iii) advanced numerical models, data-driven approaches, and multi-scale simulation techniques for predicting reactive transport in complex environmental systems. We encourage submissions integrating hydrogeology, geochemistry, microbiology, and computational methods to advance the understanding and prediction of reactive solute transport from pore to planetary scales.

Summary: Understanding WRI in complex natural systems requires integrated approaches that combine observations across multiple disciplines and spatial–temporal scales. Advances in geophysics, geochemistry, geographic information systems (GIS), remote sensing, and data science have provided powerful tools for characterizing subsurface structures, tracing fluid pathways, quantifying geochemical processes, and predicting the evolution of water–rock systems. 

This session welcomes contributions that investigate: (i) innovative applications of geophysical methods for imaging geological structures, groundwater systems, and fluid–rock interactions; (ii) GIS, remote sensing, artificial intelligence, and big-data techniques for mapping, modeling, and predicting WRI processes; (iii) interdisciplinary frameworks combining multiple datasets and analytical approaches to address complex hydrogeological and environmental challenges. We encourage submissions that demonstrate how integrated technologies can advance the characterization, monitoring, and prediction of water–rock interactions across diverse geological settings.

Summary: Groundwater systems are increasingly affected by multiple pressures related to climate variability, abstraction, land-use change, contamination and changes in recharge conditions. Hydrogeochemical and isotopic data provide critical evidence for interpreting aquifer functioning, but their full value depends on how they are integrated into hydrogeological conceptual models, monitoring strategies and management-oriented assessments.

This session focuses on the use of hydrogeochemical and isotope-based evidence to build, test and refine conceptual models of groundwater systems. Contributions are invited on approaches that combine chemical and isotopic datasets with hydrogeological observations, geophysical information, spatial analysis, time-series data and modelling tools. The emphasis will be on the integration of multiple lines of evidence to improve the interpretation of complex aquifers and to support robust assessment of groundwater vulnerability, pressures and system response.
Particular attention will be given to studies that translate scientific interpretation into operational applications. Relevant topics include conceptual-model uncertainty, monitoring-network design, early-warning indicators, model-supported scenario analysis, mitigation planning, management thresholds, and decision-support tools for groundwater protection. Case studies from different hydrogeological settings are welcome, especially where hydrogeochemistry and isotopes are used as part of an integrated framework for sustainable groundwater management.