The purpose of this study is to evaluate the level of heavy metal contamination in the spoil heaps of the former Ain Aouda mine (Taza). In this regard, solid samples of the study area were sampled. The set of analyses carried out have detected the presence of zinc (Zn), lead (Pb), copper (Cu), arsenic (As) and nickel (Ni) that remain in these metal discharges. The calculation of contamination/pollution indices: the Geo Accumulation Index (Igeo), the Enrichment Factor (EF) and the Pollution Index (IP) were used to predict the extent of heavy metal contamination. The results of this study suggest that the spoil heaps reveal polymetallic contaminations allowing the trace metal elements to be classified in the following order Zn ˃ Pb ˃ As ˃ Cu > Ni. Knowing well that the alteration and erosion of this stock of mine waste could contribute to the degradation of the natural environment by these elements that are present.

The exploitation of the Ain Aouda zinc lead mine in the Tazekka massif (Morocco) has abandoned spoil heaps stored directly on a karstified carbonated ground, without any means of precaution. The heaps were exposed to the weather agents, such as water infiltration and air circulation, which would generate a real source of pollution for the ecosystem. This pollution will inevitably produce effluents that can be loaded with metals and metalloids, which will have a significant negative influence on the soil and the environment. In this regard, the objective of this study was to confirm the existence of contamination of soils by using the technique of atomic emission spectrometry with inductively coupled plasma, and of spoil heaps by X-ray diffractometry, which confirmed the contamination by zinc, arsenic, lead and copper. Their maximum concentrations are 19858.800 (ppm), 1280.700 (ppm), 495.750 (ppm), and 328.65 (ppm), respectively. Nevertheless, it was noted that the pH of the majority of soils always remains basic, due to the significant presence of carbonates, the majority of soils are calcareous (15% to 30%) to very calcareous (> 30%). It was noticed that the phenomenon of neutralization occurs.

Acid mine drainage (AMD) threats the soils and water bodies in the territories of the sulfide mining activities all over the world. Bouaazza's mine (NE Morocco) lead and sulfides exploitation resulted in the surface exposure of large superficies of acid discharges. The results of physicochemical and geochemical analysis indicate an acidic pH (3.0-7.0) of water samples, with concentrations of lead exceeding Moroccan standards (50 µg/L). The pH in soils is considered from slight up to moderate acidic (< 6.5), with low limestone content (< 6% of CaCO 3 ), and high lead and zinc values exceeding international standards (300 mg/kg). These results indicate the high health risk generated by the absence of environmental monitoring of the mining operations which threaten the water quality in the surrounding area.