Graphene oxide-based nanocomposites (GO-chitosan and GO-EDTA) for outstanding antimicrobial potential against some Candida species and pathogenic bacteria.

To obtain the synergistic antimicrobial potential of nano-composites conjugated with graphene oxide (GO), an alternative approach was developed throughout the hybridization of chitosan (CS) or ethylene diamine tetraacetic acid (EDTA) with GO. The synthesized GO-nanocomposites were identified by XRD, HRTEM, SEM, FTIR, Zeta potential, and Raman spectroscopy. The antimicrobial activity of GO, GO-CS, and GO-EDTA was investigated against some pathogenic bacteria and Candida sp. Results showed that nano-composites looked flattened and clear, with some lines and folds on the exterior part. SEM images show the basic morphology of GO which owns remarkable holes, crevasses, and indeclinable internal structure. GO-EDTA and GO-CS possess a promising antimicrobial activity against all pathogenic microbes. In-vitro ZOI result verified that they exhibited activity against Escherichia coli (22.0 mm for GO-EDTA and 11.0 mm for GO-CS), Staphylococcus aureus (15.0 mm for GO-EDTA and 10.0 mm for GO-CS) and Candida albicans (22.0 mm for GO-EDTA and 16.0 mm for GO-CS). Microbial cells may be ultimately-damaged when they interact with GO-based nanocomposites due to different mechanisms such as oxidative and membrane stress and wrapping isolation. This work provides revolutionary GO-nanocomposites for increasing the antimicrobial activity against some pathogenic microbes with a cost-effective and eco-friendly approach.

Use of isotope hydrology in groundwater conceptualization for modeling flow and contaminant transport at northwestern Sinai, Egypt.

The study area extends along northwestern Sinai coastal plain, which is considered an integral part of the Mediterranean Sea. It depends mainly on the groundwater resource for different type of human activities such as agricultural and drinking. Many programs and policies should be implemented in this area to concurrently improve the sustainability of groundwater use and manage the risks of its degradation. Leakage from some factories in Bir El-Abd might be a contamination source that would threaten groundwater. In this paper, an attempt was made using an integrated approach of the hydrogeological setting and the conjugation of the hydrogeochemical data with the stable isotope hydrology for representation of the conceptual model of the study area. Those tools give more insights on the characterization of the groundwater system with all relevant boundaries and main recharge sources of the aquifer; which is considered to be the key components of a groundwater modeling. A particular focus is placed on modeling a hypothetical accident for contaminant transport in the groundwater system, using both lead and chromium as a typical contaminant component. Further predication of the concentration of those elements has been estimated, and the safety distances of their plume have been determined. This study would be helpful in dealing with water management issues related to contaminant hydrogeology. As well, it introduces some finding for reducing the environmental risk form the industrial development at the study area.

Hydrochemical and multivariate analysis of groundwater quality in the northwest of Sinai, Egypt.

The northwestern coast of Sinai is home to many economic activities and development programs, thus evaluation of the potentiality and vulnerability of water resources is important. The present work has been conducted on the groundwater resources of this area for describing the major features of groundwater quality and the principal factors that control salinity evolution. The major ionic content of 39 groundwater samples collected from the Quaternary aquifer shows high coefficients of variation reflecting asymmetry of aquifer recharge. The groundwater samples have been classified into four clusters (using hierarchical cluster analysis), these match the variety of total dissolvable solids, water types and ionic orders. The principal component analysis combined the ionic parameters of the studied groundwater samples into two principal components. The first represents about 56% of the whole sample variance reflecting a salinization due to evaporation, leaching, dissolution of marine salts and/or seawater intrusion. The second represents about 15.8% reflecting dilution with rain water and the El-Salam Canal. Most groundwater samples were not suitable for human consumption and about 41% are suitable for irrigation. However, all groundwater samples are suitable for cattle, about 69% and 15% are suitable for horses and poultry, respectively.

Assessment of groundwater quality using geographical information system (GIS), at north-east Cairo, Egypt.

The present investigation has been conducted to delineate the hydrogeochemical and environmental factors that control the water quality of the groundwater resources in the north-east of Cairo. A complementary approach based on hydrogeochemistry and a geographical information system (GIS) based protectability index has been employed for conducting this work. The results from the chemical analysis revealed that the groundwater of the Quaternary aquifer is less saline than that of the Miocene aquifer and the main factors that control the groundwater salinity in the studied area are primarily related to the genesis of the original recharging water modified after by leaching, dissolution, cation exchange, and fertilizer leachate. The computed groundwater quality index (WQI) falls into two categories: fair for almost all the Miocene groundwater samples, while the Quaternary groundwater samples are all have a good quality. The retarded flow and non-replenishment of the Miocene aquifer compared to the renewable active recharge of the Quaternary aquifer can explain this variation of WQI. The index and overlay approach exemplified by the DUPIT index has been used to investigate the protectability of the study aquifers against diffuse pollutants. Three categories (highly protectable less vulnerable, moderately protectable moderately vulnerable and less protectable highly vulnerable) have been determined and areally mapped.

Use of environmental isotopes and hydrochemistry as indicators for the origin of groundwater resources in El Dabaa area, northwestern coastal zone of Egypt.

The EI-Dabaa area is located on the northwestern coastal zone of Egypt and is considered to be one of the most important regions for land reclamation and agriculture. In addition, it has been selected as a potential site for constructing Egypt's first nuclear power plant.In April 1989, 14 groundwater samples were collected from the area as well as collecting samples from the Mediterranean sea and from local rainwater. These samples were subjected to chemical and environmental isotope analyses. The results of the analyses for stable isotopes (oxygen-18 and deuterium) indicate that the main recharge source of the groundwater in El-Dabaa is the local precipitation during the rainy season. Variation of the environmental tritium content as well as in the chemical composition of both major cations (Na,K,Ca,Mg) and major anions (Cl,SO4,HCO3) between different groundwaters in the studied area reflect the high degree of inhomogeneity of the aquifer and different recharging conditions due to permeability of the water bearing formation.The chemical water type of the El-Dabaa groundwater is sodium sulphate (Na2SO4) and the SAR values illustrate the suitability of these groundwaters for agricultural purposes.