<![CDATA[The Jaboi Sabang Geothermal Area in Aceh, Indonesia, comprises four active craters that release geothermal fluids and gases into surrounding water sources used by local communities for daily activities. Despite the known toxicity of arsenic (As) and mercury (Hg) in geothermal environments, baseline data on their occurrence and distribution in local water and sediment remain limited. This study assessed As and Hg contamination in water and sediment samples using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES). Water samples were collected from hot springs, bathing pools, rivers, boreholes, dug wells, and treated water, while sediment samples were obtained from craters and stream beds. Method validation showed good linearity (R² > 0.99), with limits of detection (LoD) of 10.49 µg/L for As and 1.98 µg/L for Hg, and acceptable recovery values (70–125%). The highest As and Hg instrument responses in water were observed in hot-spring sample J1, at 11.268 and 6.861 µg/L, respectively. However, the As result for J1 was above the LoD but below the limit of quantification (LoQ), indicating detection without reliable quantification, while As in J2–J7 was below the LoD. For Hg, only J1 exceeded the LoQ, whereas J3 and J6 produced responses between the LoD and LoQ. The remaining samples were below the Hg LoD. Because the applicable Hg benchmark was lower than the method LoD, compliance could not be established for samples other than J1. These findings highlight the need for improved analytical sensitivity and continued monitoring to assess potential environmental and public health risks.]]>
