Impacts on water, soil and plants from the abandoned Miguel Vacas copper mine, Portugal

Abstract

Soil, water and plant geochemistry was studied around the Miguel Vacas copper mine (Alentejo, SE Portugal), which stopped its exploitation and processing activities in 1991. After closure waste-rock piles remained exposed to weathering. The copper ore was mainly composed of copper phosphates and carbonates. Remediation actions were insufficient to prevent the spreading of waste-rock materials to surrounding farmed fields. The latter caused contamination of soils and water. Based on overall characteristics water from wells and surface stream water mostly can be classified as of the sulphate magnesium type. The application of a chemical equilibrium model to the sampled water showed that copper, phosphate and sulphate concentrations are controlled by copper(II) secondary minerals (pseudomalachite, libethenite and malachite) and gypsum. Nevertheless, groundwater can be used for irrigation and cattle based on quality parameters. Soils and plants (Prunus domestica L., Olea europaea L. spp. europaea and Quercus ilex L.) were collected southeast of the open pit and the exploitation substructures. The soils located in the influence of drainage water that percolated through waste material or exploitation substructures were contaminated with Cu, and Ni was close to the maximum value allowed by Portuguese legislation. These soils, however, did not show elevated Zn and Mn concentrations. The trace element content in plants was within the normal range, with Q. ilex being able to accumulate Mn and to some extent also Ni. Dispersion of trace elements seemed to be limited to a distance 1500 m down from the waste dumps in southeastern direction.

Geochemical background of potentially toxic trace elements in soils of the historic copper mining area: a case study from Miedzianka Mt., Holy Cross Mountains, south-central Poland

“…The similar Ni contents (37-106 mg kg -1 ) were also reported in the surface post-mining soils from the abandoned Miguel Vacas copper mine in SE Portugal (Abreu et al 2008b). Somewhat higher Ni levels (5-353 mg kg -1 ) were found in soils from the former Cu ore mines in the Sudetes Mts, SW Poland (Karczewska et al 2006).…”

“…The raised levels of Mn, 1446-4153 mg kg -1 , were found in surface soils (A-horizon) in the abandoned Miguel Vacas copper mine in SE Portugal (Abreu et al 2008b). Similarly, high Mn concentrations in post-mining soils (400-4520 mg kg -1 ) were reported from the High Moulouya Valley, Morocco (Iavazzo et al 2012).…”

“…Similarly, the contents of this metal ranged from 13 to (Iavazzo et al 2012). Much higher Cu levels in surface soils (70-2231 mg kg -1 ) were reported from the abandoned Miguel Vacas copper mine in SE Portugal (Abreu et al 2008b) or other post-mining areas, where Cu ores were extracted, e.g. 15-7200 mg kg -1 in Mexico (Razo et al 2004) and 7-3430 mg kg -1 in the Sudetes Mts, SW Poland (Karczewska et al 2006).…”

“…A relatively low number of Zn anomalies in soils of the study area occurs in the southern part of the study area. Likewise, high Zn levels (53-211 mg kg -1 ) were found in surface soils (horizon-A) of the abandoned Miguel Vacas Cu mine in SE Portugal (Abreu et al 2008b) and soils of different post-mining areas, for example, 31-835 mg kg -1 in France (Camizuli et al 2014), 46-215 mg kg -1 in northern Spain (Loredo et al 2006) or 28-3660 mg kg -1 in the abandoned Cu mines in the Sudetes Mts SW Poland (Karczewska et al 2006). Extremely high Zn concentrations (46-182,000 mg kg -1 ) were reported in soils from the High Moulouya Valley in Morocco (Iavazzo et al 2012) and from San Luis Potosi in Mexico (26-6270 mg kg -1 ) (Razo et al 2004).…”

The use of FPXRF in the determinations of selected trace elements in historic mining soils in the Holy Cross Mts., south-central Poland

“…Even in soils that are de pleted in Zn, namely light sandy soils, con centra tions of this metal are in the range of 31-61 mg/kg (Kabata-Pendias, 2011). High Zn lev els in soils were also reported from dif fer ent his toric min ing ar eas, for ex am ple, from the aban doned Miguel Vacas Cu mine in SE Por tu gal (Abreu et al, 2008), where Zn con cen tra tions were in the range of 53-211 mg/kg.…”