1. Causes and impacts of a mine water spill from an acidic pit lake (Iberian Pyrite Belt).
- Author
-
Olías, M., Cánovas, C.R., Basallote, M.D., Macías, F., Pérez-López, R., González, R. Moreno, Millán-Becerro, R., and Nieto, J.M.
- Subjects
TRACE elements ,MINE water ,BODIES of water ,ACID mine drainage ,WATER quality ,LAKES - Abstract
In May 2017, a spill from La Zarza pit lake (SW Spain) resulted in the release of approximately 270,000 m
3 of extremely acidic waters to the Odiel River. Around 780 × 103 kg of Fe, 170 × 103 kg of Al, 2.15 × 103 kg of As and high amounts of other trace metals and metalloids were spilled. The purpose of this study is to explain the causes, consequences and impacts of the mine spill on the receiving water bodies. To this end, an extensive sampling along the mine site, river and estuary as well as a hydrological model of the pit lake was performed. Around 53 km of the Odiel River's main course, which was already contaminated by acid mine drainage (AMD), were affected. The mine spill resulted in an incremental impact on the Odiel River water quality. Thus, dissolved concentrations of some elements increased in the river up to 450 times; e.g. 435 mg/L of Fe and 0.41 mg/L of As. Due to low pH values (around 2.5), most metals (e.g., Cu, Zn, Mn, Cd) were transported in the dissolved phase to the estuary, exhibiting a conservative behavior and decreasing their concentration only due to dilution. However, dissolved concentrations of Fe, Cr, Pb, Se, Sb, Ti, V and especially As decreased significantly along the river due to Fe precipitation and sorption/coprecipitation processes. At the upper zone of the estuary, a noticeable increment of metal concentrations (up to 77 times) was also recorded. The water balance illustrates the existence of groundwater inputs (at least 16% of total) to the pit lake, due probably to local infiltration of rainwater at the mining zone. The probable existence of an ancient adit connected to the pit lake indicates that potential releases could occur again if adequate prevention measures are not adopted. Image 1 • Around 270,000 m3 of extremely acidic waters were spilled from a pit lake. • An incremental impact after the spill on the already polluted Odiel River and estuary was observed. • Al, Cd, Co, Cu, Mn, Ni, Sc, U and Zn were conservatively transported to the estuary. • Cr, Fe, Se, Pb, Ti, Sb, V and As were removed from water by precipitation/sorption. • The pit lake has not yet reached equilibrium, a new spill could occur in the future. "An accidental discharge (270,000 m3 of acidic and metal-rich waters) from an abandoned pit lake to the Odiel River and its estuary caused a significant additional increase in the contaminant levels". [ABSTRACT FROM AUTHOR]- Published
- 2019
- Full Text
- View/download PDF