Composition and Origin of Mine Water at Zlatna Gold Mining Area (Apuseni Mountains, Romania)

Hydrochemical and isotopic characterization of mine water having connections with groundwater and surface water at Zlatna gold mining area (Apuseni Mountains, Romania) was performed to provide insights on mine site emissions with the surrounding environment after the cessation of mining operations. The mine water coming into direct contact with mineralization is more acidic than the mine water that only interacts with the host rock. Light isotopic composition of most mine water suggests snowmelt and high altitude precipitations as the main source of recharge. Linear correlation between δD and δ18O values indicates that all water sources belong to the meteoric cycle. For most mine water sources no significant seasonal variations of the δD, δ18O, pH and TDS values was recorded, indicating well-mixed underground systems and slow flow recharge pathways. Other mine water sources show seasonal variations of these parameters suggesting continuous recharge of mine water and a fast underground circulation. No relevant contamination of springs and phreatic water by mine water could be revealed, suggesting different underground pathways for the two types of water. On the contrary, running water is contaminated by mine water and the negative effects of acid mine drainage occur mainly in the summer months when the debit of the running water decreases.