Contamination impact and human health risk in surface soils surrounding the abandoned mine of Zeïda, High Moulouya, Northeastern Morocco

Abstract

The study assesses the levels of 16 heavy metals (HMs) in soils around the Zeida mine to provide information on the extent of contamination, the ecological risk of these HMs in soils, and the health risk to the residents of the Zeida village. Total metal concentrations were determined by inductively coupled plasma-mass spectrometry (ICP-MS) for 20 sampling stations around the mining area. The average concentrations of HMs (mg/kg) in the study area were as follows: Ag (2.3), As (90.4), Ba (1605.1), Be (3.1), Co (11.2), Cr (57.6), Cu (33.9), Mn (499.6), Mo (6.1), Ni (23.4), Pb (1338.7), Sb (7.4), Se (1.3), Sn (11.3), Sr (596.5), and Zn (87.9). They were higher than those at the control sites. Twelve single and integrated ecological risk indices, namely Nemerow Pollution Index (PINemerow), Contamination degree (Cd), and Potential Ecological Risk (RI), were used and suggested that tailings and their nearby soils had a moderate to high contamination potential. Based on the US Environmental Protection Agency (USEPA), the carcinogenic risk, non-carcinogenic, hazard quotient (HQ), and hazard index (HI) were calculated with three routes: ingestion, inhalation, and dermal for children and adults. For both children and adults, HI for HMs was in the order: Mn > As > Co > Pb > 1 > other HMs. Mn, As, and Co were hazardous at 90% of soil sampling stations, while Pb was hazardous in tailings samples. The inhalation and dermal carcinogenic risks presented negligible to acceptable levels. The ingestion carcinogenic risk posed a significant issue for As, which tended to be serious for children at the majority of sampling sites.