Abstract
The abandoned mining district of Linares (South Spain) is marked with waste from the mining and the processing of metal ores that pose an environmental hazard to watercourses. A combined analysis of waste, sediments and water was carried out to analyse the impact of a smelter on Baños Creek. The composition of the facility waste was determined using X-ray diffractometry and scanning electron microscopy. The total contents of the metal(loid)s in the waters and sediments of the watercourse were analysed, and sequential metal(loid) extraction of solid samples was carried out. The facility wastes consisted mainly of secondary minerals, such as natropharmacosiderite and spertiniite, as well as rare metal salts, such as mopungite and NaPb2(CO3)2(OH). The leachates generated by these wastes were highly alkaline, with a pH of 10 and a total dissolved solids concentration of approximately 9 g L−1. This Na-bicarbonate-type water had an As concentration above 200 mg L−1 and elevated levels of Pb, Sb and Zn (5029 µg L−1, 841 µg L−1 and 525 µg L−1, respectively). This highly contaminated lixiviate had a significant effect on the chemical quality of the waters and the bioavailability of metal(loid)s in the creek sediments, especially in the headwaters. In this zone, the As, Pb, Sb and Zn concentrations in the most mobile fraction of the sediments reached 1035 mg kg−1, 261 mg kg−1, 45 mg kg−1 and 30 mg kg−1, respectively. By comparison, smelter slag and mining waste have a much lower impact on the waters and the mobile fraction of the sediments, while significantly increasing the total concentration of these potentially toxic elements in creek sediments.
Highlights
Metal mining and the associated industries are one of the main sources of metal(loid) emissions worldwide [1,2,3,4,5], largely because of the enormous quantity of waste generated during metal smelting and the elevated concentrations of potentially toxic metal(loid)s, such as As and Pb, which are produced by refining processes [6,7,8,9]
The Zn content was high at the foot of the smelter slags (L-3) and near the San Luis smelter (Ch-5 and Ch-6, Table 3). These results indicate that the facility wastes, smelter slags and tailings ponds had significantly different effects on the creek sediments
Geochemical analyses were performed on the sediments and waters of Baños Creek and combined with a mineralogical characterisation of the facility wastes of the La Cruz smelter to reveal dispersal mechanisms of metal(loid)s for this watercourse
Summary
Metal mining and the associated industries are one of the main sources of metal(loid) emissions worldwide [1,2,3,4,5], largely because of the enormous quantity of waste generated during metal smelting and the elevated concentrations of potentially toxic metal(loid)s, such as As and Pb, which are produced by refining processes [6,7,8,9]. Notable are studies on the mineralogy and leaching potential of different types of smelter waste [18,19,20], as well as a review of the latest studies on the composition and potential environmental impact of slags [21] They revealed a remarkably large heterogeneity in metallurgical wastes in terms of the variety of trace elements and mineralogical composition
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