Heavy metal contamination of soils from abandoned mines: The case of Aouli-Mibladen-Zeïda mines in Morocco

Abstract

Contamination des sols par les métaux lourds à partir de mines abandonnées : le cas des mines Aouli-Mibladen-Zeïda au Maroc Résumé Cette étude évalue la contamination métallique des sols au voisinage des mines Aouli, Mibladen et Zeïda abandonnées dans la Haute Moulouya à l'est du Maroc, et s'attache en particulier à l'estimation de la variabilité spatiale de cette contamination et de l'étendue de l'aire contaminée. Les résultats révèlent que les sols proches des sites miniers étudiés et même très éloignés sont fortement contaminés par les métaux lourdsplomb (Pb), zinc (Zn), cuivre (Cu) et cadmium (Cd) ; ils soulignent également une grande variabilité des concentrations non seulement entre les trois sites miniers mais aussi dans un même site minier. L'index de pollution des sols étudiés est généralement élevé même pour les sols échantillonnés en aval à plus de 130 km des sites miniers, alors qu'il est extrêmement élevé en surface des verses de résidus miniers soulignant que ces dernières constituent en l'état des sources pérennes de contamination par les métaux lourds. L'aire insalubre touchée par la pollution métallique issue des sites miniers abandonnés dans la Haute Moulouya est très vaste suite à la dispersion, par les transports éoliens et hydriques, des polluants résiduels des rejets miniers abandonnés sur place. Des mesures de remédiation doivent être prises afin d'immobiliser les polluants et limiter leur transport vers l'environnement. AbstractHeavy metal contamination of soils from abandoned mines: The case of Aouli- Mibladen-Zeïda mines in MoroccoThis study assesses the metal contamination of soils in the vicinities of Aouli, Mibladen and Zeïda mines abandoned in the High Moulouya in eastern Morocco focusing in particular on its spatial variability as well as on the extent of the contaminated area. The results show that the studied soils close to mining sites and even very remote are highly contaminated with heavy metals: Pb, Zn, Cu and Cd. The results also highlight great variability in concentrations between soils of the three mining sites as well as at the same mining site. The index of soil pollution is generally high even for soils sampled downstream located at more than 130 km from the mining sites, while surface levels on tailings are extremely high, indicating that they are perennial sources of contamination by heavy metals. The insalubrious area affected by metallic pollution derived from the abandoned mining sites in the high Moulouya is very large due to dispersal by wind and water transport of metallic pollutants of mine tailings. Remedial measures must be taken to immobilize pollutants and limit their transport to the environment.

Diversity and Antimicrobial Activities of Actinobacteria Isolated from Mining Soils in Midelt Region, Morocco

“…In line with prior research on the assessment of trace metal contamination levels in sediments and water from these mining sites [ 16 , 35 , 36 ], we have been exploring extreme environments (the Dead Sea in Jordan and hypersaline sites in the Pre-Rif region in Morocco) [ 22 , 37 ] for the isolation of bacteria of biotechnological potential. We were the first group searching for Actinobacteria from Ahouli-Mibladen-Zaida mining areas and determining their potential to produce antimicrobial agents.…”

“… (a) Map of sampling sites of Actinobacteria isolation from the region of Midelt, between the Middle and High Atlas mountain ranges, in Morocco. (b) Positioning of the sampling sites of this study on the map drawn by El Hachimi et al [ 16 ]. (c) Pictures of the sampling sites related to the present study.…”

“…Morocco, with its distinctive climate and geographical position, represents a multitude of diverse ecological niches, many of which are considered extremes, such as saline biotopes, arid deserts, thermophilic sources, and polymetallic mines [15][16][17]. However, scarce data are available on the diversity and ecological roles of microorganisms and, more precisely, Actinobacteria living in the such ecosystems [18][19][20][21][22][23].…”

The canary in the mine: Mediterranean mines as indicators of the hold on territories and resources: French Pyrenees, Moroccan Middle Atlas, and Tunisian coastal mountains

“…The three sites were chosen according to their dispersion along Western Mediterranean shores, including the fact that they belong to mountainous locations. They were also considered the most important abandoned mines within their region and within the expertise of the co-authors of the article, having extensively worked on one or several selected sites (EL El Hachimi et al, 2014;Hamrita et al, 2017;Saqalli et al, 2020). It appears that the direct links between these mines, the fact, for instance, that some private companies were involved in more than one site, were not initially anticipated.…”

Heavy Metal(oid)s Contamination and Potential Ecological Risk Assessment in Agricultural Soils

“…Heavy metal(oid)s usually enter into the soils from lithogenic and anthropogenic sources [ 13 ]. Industrial activities, mining and smelting activities, electroplating, petrochemical activities, fossil fuel burning, waste disposal, agriculture activities, construction activities, irrigation water, vehicular exhausts, atmospheric deposition, etc., are potential anthropogenic sources of the heavy metal(oid)s in soils [ 12 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. High levels of heavy metal(oid)s in soils are associated with a number of effects, such as changing the physicochemical properties of soil, affecting the human health (both directly and indirectly) and impacting animal life.…”