Assessment of drinking water quality based on trace elements concentrations in the semi-arid region, Morocco

Abstract

Human health and sustainable socio-economic growth are closely linked to water quality. Due to increasingly intense human activity, pollutants, and in particular trace elements, are entering the aquatic system and harming humans. The main objective of this study is to analyse and compare the impact of the trace elements on the water quality of natural springs. The concentrations of ten trace elements in 12 spring water samples collected in 2022 were analyzed using ICP-MS to determine the spatial variability of natural water quality in the Ouislane watershed. Nine major trace elements (boron, cobalt, chromium, copper, manganese, nickel, lead, zinc, and vanadium) were measured using the inductively coupled plasma mass spectrometry (ICP-MS) technique. The average values of these elements followed the descending trend: B > Ni > Cr > Co > Zn > Mn > V > Cu > Pb in spring water samples. Some trace elements measured in certain water samples exceed the upper limits set by Moroccan drinking water quality standards (NM) and the World Health Organization (WHO). From the principal components analysis (PCA), 83% of the variation is explained by the first three main components. B, Co, Cr and Ni have a strongly impact on water quality explain by their strong correlation with CP1 (R² > 0.70). The calculated water quality index (WQI) values ranged from 61.18 to 95.11, with an average of 78.47. Approximately 17% of the water samples were categorized as excellent quality water (WQI < 50), with the remaining 83% classified as good quality water (50 < WQI < 100). According to the WQI index, all the natural spring waters investigated are deemed suitable for human consumption.