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2.
Environ Monit Assess ; 193(11): 703, 2021 Oct 08.
Artículo en Inglés | MEDLINE | ID: mdl-34623531

RESUMEN

The Nile River is the soul of Egypt, providing more than 95% of its freshwater demand. However, it receives different pollutants discharged into the water body along its stretch from Aswan (downstream of the High Dam) to Cairo, which is approximately 950 km. Alternatively, sediments play an important role in the dynamics of the entire aquatic environment and act as a sink or a source of pollution in the overlying water under various conditions. This study assessed sediment quality and its heavy metal levels. Several indices and human health risks were determined to assess the potential ecological risk of the Nile River sediment. On the basis of the index results, Cd registered the highest pollution ranking, whereas Fe, Mn, Zn, Cu, and Ni had the lowest effect. In another context, southern sites represented the lowest ecological risk relative to the central and northern sectors. The results of the noncarcinogenic hazard indices, hazard quotient, and hazard index in addition to the lifetime cancer risk were below the acceptable international limits, confirming that there are no adverse effects on the exposed population due to the Nile sediment.


Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , Egipto , Monitoreo del Ambiente , Sedimentos Geológicos , Humanos , Metales Pesados/análisis , Medición de Riesgo , Contaminantes Químicos del Agua/análisis
3.
Environ Sci Pollut Res Int ; 27(16): 18985-19003, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-30280341

RESUMEN

Ni-Al-CO3-layered double hydroxide (LDH) with Ni:Al ratio (3:1) and their nanocomposites with alginate and chitosan beads were prepared and examined for their efficiency in removal of Cd2+ and Cu2+ ions from wastewater. Different parameters such as contact time, pH value, adsorbent weight, and heavy metal ion concentration on the removal efficiency were examined and reported. The prepared beads were examined using X-ray diffraction (XRD), TEM, SEM, and FTIR. Our results revealed a successful preparation of the LDH in rhombohedral hexognal crystal form and the alginate-LDH-chitosan beads. The optimized batch experiment conditions in ambient room temperature were found to be 2 g/L adsorbent dose, 50 mg/L initial concentration of meal, contact time of 2 h, and pH ~ 5 and 6 for removal of Cu2+ and Cd2+, respectively. The adsorption process was well fitted with Langmuir and Freundlich isotherm models (higher R2), with trivial advantage for Freundlich approach. Kinetic studies showed that the adsorption of both Cd2+ and Cu2+ followed the pseudo-second-order. The current study demonstrated that the Ni-Al-CO3 LDH and their novel alginate-chitosan-based nanocomposite could be further tailored and used as efficient adsorbents for the uptake of heavy metals from wastewater.


Asunto(s)
Quitosano , Nanocompuestos , Contaminantes Químicos del Agua , Purificación del Agua , Adsorción , Descontaminación , Concentración de Iones de Hidrógeno , Hidróxidos , Cinética , Agua
4.
Environ Monit Assess ; 187(6): 346, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-25968553

RESUMEN

This study establishes a baseline for trace metal speciation in Qarun and Wadi El-Rayan lakes. A five-step sequential extraction procedure was applied for the speciation of the Fe, Mn, Zn, and Cu in sediment samples collected at Qarun and Wadi El-Rayan lakes. Mn and Cu were the most mobile metals, whereas the residue fraction maintained the highest concentrations of Zn and Fe (≈ 60 %). No significant differences in metal concentrations were detected in the sediments of each lake sites, despite of the large distance between them (P > 0.05). Hazardous discharge sources are responsible for the high accumulation of metals in the nonresidual fractions. Qarun Lake showed high mobility factor for all studied metals than Wadi El-Rayan lakes; as such, all the humans, plants, animals and the general biota within the vicinity of this aquatic system are quite vulnerable to the trace metal exposure. According to geoaccumulation index (I-geo), the studied sediments were practically uncontaminated by Fe and Mn and classified as uncontaminated to moderately contaminated with Cu in Qarun and Zn in Wadi El-Rayan lakes. The low values of load pollution index (<1), confirmed the unpolluted condition of the lakes' superficial sediments.


Asunto(s)
Sedimentos Geológicos/química , Lagos/química , Metales Pesados/análisis , Contaminantes Químicos del Agua/análisis , Fraccionamiento Químico , Egipto , Monitoreo del Ambiente/métodos , Medición de Riesgo
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