Details

Autor(en) / Beteiligte

• Jiménez Beltrán, Jon
• Marazuela, Miguel Ángel
• Baquedano, Carlos
• Martínez-León, Jorge
• Sanchez Navarro, Jose Ángel
• Cruz-Pérez, Noelia
• Santamarta, Juan C.
• García-Gil, Alejandro

Titel

The genesis of an extremely acidic perched aquifer within roasted pyrite waste in a fully urbanized area (Zaragoza, Spain)

Ist Teil von

• The Science of the total environment, 2023-10, Vol.896, p.165293-165293, Article 165293

Ort / Verlag

Netherlands: Elsevier B.V

Erscheinungsjahr

2023

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Contaminated groundwater is a serious problem in developed countries. The abandonment of industrial waste may lead to acid drainage affecting groundwater and severely impacting the environment and urban infrastructure. We examined the hydrogeology and hydrochemistry of an urban area in Almozara (Zaragoza, Spain); built over an old industrial zone, with pyrite roasting waste deposits, there were acid drainage problems in underground car parks. Drilling and piezometer construction, and groundwater samples revealed the existence of a perched aquifer within old sulfide mill tailings, where the building basements interrupted groundwater flow, leading to a water stagnation zone that reached extreme acidity values (pH < 2). A groundwater flow reactive transport model was developed using PHAST to reproduce flow and groundwater chemistry, in order to be used as a predictive tool for guiding remediation actions. The model reproduced the measured groundwater chemistry by simulating the kinetically controlled pyrite and portlandite dissolution. The model predicts that an extreme acidity front (pH < 2), coincident with the Fe (III) pyrite oxidation mechanism taking dominance, is propagating by 30 m/year if constant flow is assumed. The incomplete dissolution of residual pyrite (up to 18 % dissolved) predicted by the model indicates that the acid drainage is limited by the flow regime rather than sulfide availability. The installation of additional water collectors between the recharge source and the stagnation zone has been proposed, together with periodic pumping of the stagnation zone. The study findings are expected to serve as a useful background for the assessment of acid drainage in urban areas, since urbanization of old industrial land is rapidly increasing worldwide. [Display omitted] •Water stagnation due to concrete barriers enhances acid drainage problems in urban areas.•Acid drainage from pyrite oxidation leading to SO4-rich waters increases concrete dissolution.•Water residence time may control acid drainage development in urban areas.•An extreme acidity (pH < 2) front propagates due to differential residence times.•Water collectors and restriction of recharge can prevent acid drainage in urban areas.