Recharge and contamination sources of shallow and deep groundwater of pleistocene aquifer in El-Sadat industrial city: isotope and hydrochemical approaches

Abstract

Hydrochemical and isotopic researches were conducted in El-Sadat City groundwater system to identify groundwater alteration, recharge, residence time and extent of pollution. The groundwater salinity gradually increases as the groundwater moves from northeastern to southwestern parts of the city. Groundwater generally shows mineralization decreasing with depth, indicating that the possibility of recent water penetration far below the surface is limited. Shallow groundwater has an elevated level of nitrate, which is attributed to anthropogenic sources due to intensive agricultural activity. The limit of high nitrate water may mark the maximum penetration of groundwater from the surface, which is found in depths \100 m. The northeastern and southwestern industrial areas are highly contaminated by some heavy metals, which may originate from some local industrial effluents. The sewage oxidation ponds seem to show no effect on groundwater; hence, these ponds are not a point source for these heavy metals. Dissolved ions depict five different hydrochemical facies, and stable isotopes define the recharge mechanisms, the origin of groundwater and the hydraulic confinement of deep groundwater. The deep groundwater is untritiated and has long residence times (in the order of thousands of years). Three different hydrochemical groups have been recognized and mapped in El-Sadat City, based on the chemical and isotopic information of the groundwater. These groups have different levels of contamination. The deep groundwater samples are significantly less impacted by surface activities and it appears that these important water resources have very low recharge rates and would, therefore, be severely impacted by overabstraction. The extensive exploitation of groundwater for drinking water supply would shortly be reflected by a gradual decline of the groundwater table in El-Sadat City. Amelioration of groundwater quality requires further management strategies and efforts in the forthcoming years.

Global Isotope Hydrogeology―Review

“…Precipitation δ 18 O values plotted in panel b are ‘amount‐weighted’ over the entire period of record, meaning time‐steps during which more precipitation fell are weighted more than those during which less precipitation fell. Groundwater δ 18 O data presented here are derived from the United States' National Water Information System (data downloaded May 2018 from www.waterqualitydata.us) and from data sets compiled from the following n = 435 references (Al Faitouri & Sanford, ; Abid et al, ; Abid et al, ; Abid et al, ; Abouelmagd et al, ; Abu‐Jaber & Kharabsheh, ; Adams et al, ; Adiaffi et al, ; Adomako et al, ; Aeschbach‐Hertig et al, ; Aggarwal et al, ; Ahmad & Green, ; Ahmed et al, ; Ako Ako et al, ; Al‐Charideh & Abou‐Zakhem, ; Al‐Charideh, ; Al‐Charideh & Kattan, ; Al‐Charideh & Hasan, ; Alemayehu et al, ; Al‐Katheeri et al, ; Allen, ; Al‐Mashaikhi et al, ; Alpers & Whittemore, ; Al‐Ruwaih & Shehata, ; Alsaaran, ; Alyamani, ; Amer et al, ; Andre et al, ; Andrews et al, ; Andrews, Edmunds, et al, ; Andrews, Fontes, et al, ; Aravena et al, ; Arslan et al, ; Atkinson et al, ; Awad, ; Awad et al, ; Awad et al, ; Awad, ; Back et al, ; Bahati et al, ; Bajjali & Abu‐Jaber, ; Bajjali, ; Bakari, Aagaard, Vogt, Ruden, Brennwald, et al, ; Baker, ; Barbecot et al, ; Batista, Santiago, Frischkorn, Filho, & Forster, ; Bayari et al, ; Bennetts et al, ; Berg & Pearson, ; Beyerle et al, ; Beyerle et al, ; Bhatia et al, ; Bhattacharya et al, ; Blomqvist, ; Böhlke et al, ; Bouchaou e...…”

Seasonal Groundwater Quality Status and Nitrogen Contamination in the Shallow Aquifer System of the Kathmandu Valley, Nepal

“…These concerns are more severe in areas in which groundwater is the primary source of fresh water [5,6], as well as in the densely populated areas of developing countries due to improper infrastructure [7][8][9]. The groundwater beneath such areas may contain various organic and inorganic compounds that readily affect the groundwater environment [10,11].…”