<p>Groundwater Arsenic contamination is a critical environmental and public health concern in reducing aquifers, including the shale gas-bearing regions of Sindh, Pakistan. This study investigates the geochemical controls on arsenic mobilization in groundwater, emphasizing how shale gas exploration may induce methane-rich, reducing conditions that enhance the release of arsenic from aquifer sediments. For the present study, two active gas extraction sites (Qadirpur, Ghotki, and Kunnar, Hyderabad District) in the lower Indus basin were selected. A total of 81 groundwater samples were analyzed for cations, anions, trace elements, and dissolved light hydrocarbons. The groundwater analyzed at Site Q (Qadirpur) showed that Ca²⁺ (27%), K⁺ (10.8%), Fe (67.6%), Mn (91.8%), and As (100%) exceeded the WHO limits of drinking water. High dissolved CH₄ (0.31 to 11.25&#xa0;mg/L) was also detected at site Q. Whereas groundwater at Site K (Kunnar) showed that 50% of the samples exceeded the WHO limit for Ca²⁺, 28.8% for Mg²⁺, 33.3% for Na⁺, 13.9% for K⁺, 27.8% for Cl⁻, 75% for SO₄²⁻, 100% for Fe²⁺, 77.7% for Mn²,⁺ and 88.9% for As exceeded the WHO limits, with low CH₄ (0.11 to 0.71&#xa0;mg/L) concentrations. Methane in the study area is likely of biogenic or mixed biogenic-thermogenic origin. Its presence reflects reducing conditions that can facilitate As mobilization through the reductive dissolution of iron and manganese minerals. Our findings indicate that hydraulic fracturing fluids interacting with shale formations may trigger various geochemical reactions, including pyrite oxidation, carbonate dissolution, clay transformation, and trace element desorption and complexation. These processes may exacerbate the contamination pattern and enhance arsenic release in the region.</p>