Characterizing Local Effects on Arsenic Risk through Quantification of Geochemical Controls on Arsenic Mobilization and Speciation

Objective

Groundwater contamination by arsenic (As) is a major global health challenge, threatening millions of people. In Southeast Asia, particularly Vietnam’s Mekong and Red River Deltas, groundwater As concentrations often exceed WHO limits by 10–100 times. In Europe, legacy mining has caused elevated As levels in floodplain soils along rivers such as the Ogosta (Bulgaria) and Mulde (Germany). Predicting to what extent As is released under specific soil and groundwater conditions remains extremely difficult because existing studies are mainly observation-based and site-specific. What is missing are quantitative relationships that link soil geochemical parameters (iron and manganese oxides, organic carbon, texture, and sulfate) to As mobilization and transformation. To address this gap, CLEAR-As will: (1) establish a baseline of geochemical parameters for Mekong soil; (2) systematically quantify the individual and combined effects of these parameters on As mobilization and chemical form, and identify the controlling parameter(s); and (3) testing whether these controls show consistent effects across soils from Red, Ogosta, and Mulde River area. CLEAR-As will be hosted at the Environmental Chemistry Group at the University of Neuchâtel, with expertise in laboratory soil incubations and synchrotron-based spectroscopy analyses, and will be supported by collaborators with expertise in As speciation (METAS, Switzerland), microbial analysis (EKUT, Germany), and field sampling (HCMUT, Vietnam). Through an interdisciplinary approach, the project will generate the first quantitative relationships between soil geochemical parameters and As mobilization and transformation. CLEAR-As will support Horizon Europe priorities and the UN Sustainable Development Goals on clean water and health, while equipping the Researcher with advanced skills in soil biogeochemistry and analytical techniques, strengthening the path to scientific independence.