SEASONAL VARIATION OF HEAVY METAL POLLUTION OF GROUNDWATER AND SOIL IN THE M’NASRA REGION (GHARB, MOROCCO)

Serine  OMRANIA; Najib EL  KHODRANI; Mbark  LAHMAR; Ahmed   DOUAIK; Hamza   IAAICH; Souad EL  HAJJAJI; Abdelmjid  ZOUAHRI

doi:10.18006/2021.9(6).813.822

Authors

Serine OMRANIA Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Waters and Environment, CERNE2D, Faculty of Sciences, Mohammed V University, Rabat, Morocco
Najib EL KHODRANI Research Unit on Environment and Conservation of Natural Resources, Regional Center of Rabat, National Institute of Agricultural Research (INRA), Rabat, Morocco
Mbark LAHMAR Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Waters and Environment, CERNE2D, Faculty of Sciences, Mohammed V University, Rabat, Morocco
Ahmed DOUAIK Research Unit on Environment and Conservation of Natural Resources, Regional Center of Rabat, National Institute of Agricultural Research (INRA), Rabat, Morocco
Hamza IAAICH Research Unit on Environment and Conservation of Natural Resources, Regional Center of Rabat, National Institute of Agricultural Research (INRA), Rabat, Morocco
Souad EL HAJJAJI Laboratory of Spectroscopy, Molecular Modeling, Materials, Nanomaterials, Waters and Environment, CERNE2D, Faculty of Sciences, Mohammed V University, Rabat, Morocco
Abdelmjid ZOUAHRI Research Unit on Environment and Conservation of Natural Resources, Regional Center of Rabat, National Institute of Agricultural Research (INRA), Rabat, Morocco

DOI:

https://doi.org/10.18006/2021.9(6).813.822

Keywords:

Groundwater, Heavy Metal, Hierarchical cluster analysis, Nemerow index, Soil, Vertical transfer

Abstract

M’nasra region is well known for increasing levels of heavy metal pollution in the environment, mainly due to waste discharge of Ouled Berjal, the irrational use of fertilizers, and the discharge of waste from several industries. The objective of this study was to access the seasonal variations in the groundwater and soil quality with respect to heavy metal pollution. Water samples from wells and samples from soil near them were taken during wet (January - March 2017) and dry (July 2017) seasons and concentrations of Cd, Cu, Cr, Mn, Ni, Pb, and Zn were determined using an Atomic Absorption Spectrophotometer (AAS). Contamination factor for each heavy metal and Nemerow pollution index was calculated. Results of the study revealed a decrease in pollution degree from wet to dry for soil and an increase in the case of groundwater. Cu had the lowest and Ni had the highest concentration in irrigation water whereas, for soil, Cd had the lowest and Zn had the highest concentration. During the wet season, all the concentrations of heavy metals decreased compared to the dry season, this can be explained by the dilution of these concentrations by precipitation water and therefore to lower absorption of these heavy metals in the water of irrigations and/or soil. Vertical transfer of pollutants from topsoil to groundwater was assessed using Hierarchical Cluster Analysis to identify associations between heavy metals and soil texture. In the case of Ni and Cr, the variables corresponding to the concentrations from soil and groundwater were part of the same cluster, in both seasons, the distribution maps of concentrations confirmed the pattern of transfer. This study can be considered as a baseline for the seasonal variation of heavy metal pollution of groundwater and soil. This study can be used not only for monitoring the study area but also as a tool for the implementation of environmental protection policies.