Geochemical characterisation of surface waters, topsoils and efflorescences in a historic metal-mining area in Spain

Abstract

Purpose Mining activities generate large amounts of wastes that may contain potentially toxic elements (PTE), which, if released into the environment, may cause air, water and soil pollution long after mining operations have ceased. This paper describes the environmental relevance of efflorescences, topsoils and surface waters from the abandoned mine of Sierra Minera of Cartagena-La Unión, SE Spain. The exposure of the population to arsenic and the associated risk were also assessed. Materials and methods A total of 10 topsoils and surface waters and 11 efflorescences affected at varying degrees by mining activities were studied. The total potentially toxic element content (As, Cd, Cu, Fe, Pb and Zn) was determined in all samples. In addition, the mineralogical composition of solid samples was determined by X-ray diffraction and some efflorescences were also analysed using a scanning electron microscopy-energy dispersive X-ray spectrometer. Finally, an arsenic-intake risk assessment was carried out, both as regards carcinogenic and non-carcinogenic effects and considering the total and the bioaccesible As content. Results and discussionThe study area is heavily polluted as a result of historical mining and processing activities, during which time great amounts of wastes were produced, characterised by a high PTE content, acidic pH and minerals resulting from supergene alteration. The supergene mineralogical assemblages include soluble metal salts, mainly sulphates, iron hydroxysulphates and iron oxyhydroxides, all of which form ochreous precipitates. Topsoil samples showed risk values and hazard quotients higher than the reference levels, particularly for children. In the efflorescences, these values were lower but still unacceptable. Conclusions The efflorescences are of significance for monitoring purposes because they are involved in cycles of retention release of hydrogen ions, sulphate and potentially toxic elements. In addition, in a semi-arid climate, such as the study area, these minerals contribute to our understanding of the response of the system to episodic rainfall events. In general, it was observed that the arsenic in collected samples represent a potential risk for human health through ingestion.

Electrical Resistivity Tomography as a Support Tool to Estimate Physicochemical Properties of Mining Tailings Pond

“…Finally, Cu was 4-fold higher than its NGR (30 mg kg -1 ). Similar concentrations of Zn, Pb and Cd were found in tailings ponds from the Cartagena-La Unión mining district [11,57,58].…”

Integrated Management of Pig Residues and Copper Mine Tailings for Aided Phytostabilization

“…Ryegrass productivity is restricted on mine tailings due to limiting nutritional (N, P, K), chemical (acidity, salinity, metal toxicity), and physical (low OM content, compaction) factors (Ye et al, 2002; Verdugo et al, 2010; Pérez‐Sirvent et al, 2016). The present study showed that incorporation of selected pig residues into Cauquenes tailings resulted in significantly increased ryegrass productivity.…”

Why do people continue to live near polluted sites? Empirical evidence from Southwestern Europe

“…Using cadastral data, a random selection of housings was employed to guarantee the representativeness of study areas regarding demographic and socioeconomic characteristics. We (Sivry et al 2010, Patinha et al 2014, Pérez-Sirvent et al 2016. Pollution is spread in the polluted municipalities but does not spill over to the control areas.…”