In the last few years, the northwestern coastal zone of Egypt has been affected by many stresses that impact its water resources, leading to undesirable consequences related to water quantity and quality. This paper aims to evaluate the possible contamination sources of shallow aquifers in the El‐Omayed area, Egypt, that are causing its deterioration; this was achieved through an integration of hydrochemical and isotopic techniques, an assessment of the undesirable consequences of potential toxic metals (PTMs) on human health risk as a result of direct water consumption, and finally, the application of biological treatment in the remediation of some metal contamination. The chemical composition, environmental isotopes (δ18O and δ2H), and microbial analyses were analyzed from 13 collected water samples. Approximately 20% of the groundwater samples were classified as fresh water, and the rest were classified as slightly saline to moderately saline. Stable isotopes proved the contribution of the El Sheikh Zoied canal (which is mainly recharged from the Nile system) as a recharge source. The toxicity of PTMs (Cd, Cu, Co, Cr, Pb, Zn, B, and Fe) was evaluated on the basis of their exceedance values. It was proven that the majority of the groundwater samples were contaminated, which might be attributed to natural and anthropogenic actions in the study area; however, according to human health risk exposure assessment calculations, there is no human cancer risk posed via ingestion of drinking groundwater. The total bacterial count was determined for all water samples; autochthonous microorganisms were capable of removing heavy metals in the polluted water sample. The bacterial strain M52, which was identified by 16S rRNA sequencing as Stenotrophomonas rhizophila, showed the best results, by removing 75% and 65% of the initial concentrations of Fe and B, respectively. The results indicate that this bacterial strain may be useful and represents an environmentally friendly method to remove pollutants and heavy metals from contaminated water. Integr Environ Assess Manag 2020;16:461–471. © 2020 SETAC

The interaction of Nucleon-Nucleon (N N ) has certain physical characteristics, which indicated by nucleon, and meson degrees of freedom. The main purpose of this work is calculating the ground state energies of 2 1 H and 4 2 He through the two-body system with the exchange of mesons (π, σ, ω) that mediated between two nucleons. This paper investigates NN interaction based on the quasirelativistic decoupled Dirac equation and self-consistent Hartree-Fock formulation. We construct one-boson exchange potential (OBEP) model, where each nucleon is treated as a Dirac particle and acts as a source of pseudoscalar, scalar, and vector fields. The potential in the present work is analytically derived with two static functions of meson, the single particle energy dependent(SPED) and generalized Yukawa (GY) functions, the parameters used in meson functions are just published ones (mass, coupling constant,and cut off parameters). The theoretical results are compared to other theoretical models and their corresponding experimental data, one can see that the SPED function gives more satisfied agreement than the GY function in case of the considered nuclei.

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This research aims to assign the specific and potential sources that control migration and transformation mechanisms of ammonium/nitrate contaminants of surface and groundwater systems in the southwestern Nile Delta, Egypt. To achieve that, an integration of hydrogeochemistry, multiple environmental stable isotopes (δ2H-H2O, δ18O-H2O, δ15N-NH4, and δ15N-NO3) coupled with three-dimensional nitrogen transport numerical model (MODFLOW-MT3D) was done. A set of representative water samples (20 canals and drainage water) and 14 groundwater samples were collected and analyzed for physical, chemical, and stable isotope analysis. NH4+ and NO3− concentrations in surface water samples varied from 0.29 to 124 mg/l and 0.52 to 39.67 mg/l, respectively. For groundwater samples, NH4+ and NO3− concentrations varied from 0.21 to 1.75 mg/l and 0.33 to 32.8 mg/l, respectively. Total risk quotient (THQ) level of nitrate (oral and dermal effects) from drinking water exceeds unity for all water samples indicating a potential noncancer risk for the southwestern Nile Delta residents. The potential sources of nitrogen compound pollution are water from sewage treatment plants used for irrigation, sludge and animal manure, septic tanks, soil nitrogen, and artificial fertilizers according to results of δ15N values. Results of ammonium/nitrate modeling in shallow groundwater aquifers are compared with observed concentrations and are found to be in good agreement. Some recommendations are given to decrease nitrogen loads in the study area through suggested a need for adoption of N-fertilizer management practices and treatment of sewage water before to application in agricultural activities.

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Sustainable groundwater resources are a critical issue for national development in developing countries like Egypt, which is characterized by a semi-arid to arid climate and low per capita share of fresh water as a result of progressive population increase and especially after the construction of the Great Ethiopian Renaissance Dam. It is mandatory to adopt and modify methods suitable for preserving and efficient use of available water resources. The Eocene carbonate aquifer in the desert area under study (West El-Minia, Mid-Upper Egypt) is partially renewable; its sustainable development in irrigation is explored in this work. The (recharge–withdraw–exploit) regimes have been optimized by keeping the well abstraction below the fraction of renewable recharge and maximizing the exploit by selecting low water -consuming crops of high economic value. A novel approach is introduced in this work by integrating isotope hydrology techniques with numerical modeling; environmental isotopes (18O and D) contents of 62 groundwater samples have been used to determine and map the contribution of recent recharge in the study area (from 10 to 95%) and to constrain the acceptable reduction in hydraulic head allowed under an optimized withdraw and usage regime. Different scenarios were proposed by changing (rate of pumping, number of wells, wells distribution and irrigated crops) and simulating aquifer behavior to achieve the sustainable yield goals and the best plan for groundwater management in the study area. Graphical abstract