Arsenic Speciation as a tool for groundwater quality assessment and sustainable water management: Evidence from the Almopia Basin, Northern Greece

Arsenic (As) is referred as a potentially toxic element (PTE) and is commonly present in rocks, soils, and water. Bioaccumulation of As poses significant risks to human health. The World Health Organization (WHO) and the European Union have established a maximum guideline value of 10 μg·L−1 for As in drinking water. Elevated As concentrations have been reported in thermal spring- and ground- waters globally. The distribution of arsenic species, specifically trivalent arsenite [As(III)] and pentavalent arsenate [As(V)], in natural waters is primarily influenced by geochemical conditions such as redox and pH [1]. Under oxidizing conditions, such as those found in surface waters, As(V) predominates and is mainly present as oxyanions (H2AsO4−, HAsO42−). In mildly reducing environments, As(III) is the dominant species and remains mostly as neutral arsenious acid (H3AsO3) at typical natural water pH levels (