Heavy Metals Analysis and Quality Evaluation in Drinking Groundwater around an Abandoned Mine Area of Ouichane (Nador’s Province, Morocco)

Abstract

The eventual polluting of the Ouichane region's groundwater by heavy metals around an abandoned iron mine was investigated. To reach this aim, the research began with a questionnaire survey to assess local people's use of and appreciation for well and spring water, followed by measurement of spatial pollution load of heavy metals: Al, Ag, Fe, Cd, As, Cr, Co, Zn, Pb and Cu for water samples collected from twelve wells and three spring drinks of water using inductively coupled plasma-atomic emission spectrometry method (ICP). Determining the overall quality of spring and well water for human use was also performed by calculating the heavy metal pollution index (HPI). As result, the survey revealed that 44.90% of the households are not connected to the drinking water network, 97.3% of them use well water, which is highly appreciated, and 88.1% of the population consider its quality to be good to excellent. Meanwhile, the ICP analysis showed that all the water samples contain heavy metals. In fact, the maximum concentrations (expressed in 10-5g/l) recorded per element were 9.7 for (Ag), 15 for (Al), 6.9 for (As), 4.5 for (Cd), 5.6 for (Co), 31 for (Cr), 14 for (Cu), 858 for (Fe), 7 for (Pb) and 2.9*10-5g/l for (Zn). Moreover, most of the water samples recorded heavy metal values above World Health Organization (WHO) limits, for at least one metal among the ten tested, with high concentrations of iron observed in all samples. The HPI values for the three explored sources (S1, S2 and S3) and for 8 out of 12 wells (P3, P4, P5, P6, P7, P8, P9 and P10) exceed the critical pollution value and identify non-potable water with a high potential of contamination. Consequently, the results of this study raise the question about groundwater around this abandoned mining area, especially in the long term, the use of groundwater could increase because of the succession of years of drought on Moroccan territory and hence may constitute a significant health risk for most of the inhabitants.