Risk Assessment and Hazardous Effects of Metal Contamination in O. niloticus and S. galilaeus from Four Islands of the River Nile.

The Nile River islands are recognized as the most productive lands in Egypt. Although, these islands are vulnerable to several natural and man-made crises. The present study was aimed to evaluate the consequences of different anthropogenic activities on the heavy metals load and histological alterations in O. niloticus and S. galilaeus collected from four different Nile River islands along the Great Cairo sector (Egypt), and the possible health risks for human consumers. Metals were accumulated in both fish muscles in the following order: Fe > Zn > Cu > Mn > Pb. S. galilaeus was recorded higher metal pollution index than O. niloticus, while El-Warrak Island was documented the highest MPI and hazard quotient among all sampling sites. All sampled tissues were recorded histopathological lesions in both fish. The present study may be considered as an early alert for habitual consumers, particularly at high consumption rates of some fish species.

Heavy metal pollution in Manzala Lake sediments, Egypt: sources, variability, and assessment.

The environmental pollution of lake systems due to anthropogenic factors is of growing concern worldwide. Manzala Lake is the largest northern coastal-deltaic lakes of Egypt and has socioeconomic impacts. In this study, the concentrations and origins of seven heavy metals (HMs) and the organic content in the Manzala Lake sediments were explored during the winter and summer. The concentration of the HMs and the organic content were quantified using inductively coupled plasma and loss-on-ignition techniques. Pearson's correlation coefficient (PCC) and principal component analysis (PCA) were applied to evaluate the sources of the metals in the sediments. The HMs and organic matter were enriched during the winter season. The average concentrations of the HMs in the sediments conformed to the following sequence: Fe (14.13) > Mn (0.8) > Cu (0.11) > Zn (0.11) > Ni (0.06) > Pb (0.5) > Cd (0.002) (mg/kg). Sediment quality protocols showed that Mn, Cd, Cu, and Ni pose a significant threat to the aquatic environment in Manzala Lake. The geoaccumulation index (Igeo) values indicated pollution of the sediments with most metals, excluding Fe and Ni. The periodic mean Igeo pollution level followed the sequence Cd > Cu > Zn > Mn > Pb > Ni > Fe. The greatest pollution load index noted during the winter season was principally induced by Cd and Cu. The overall ecological risk index was moderate, with Cd being the most prominent HM. PCA combined with PCC showed that the HM enrichments in the southern (Bahr Al-Baqar Drain [S1], Bashteer [S3], Legan [S5], and Al-Ginka [S8]) and the extreme northeastern (El-Qapouti [S6]) parts of Manzala Lake sediments were mainly due to the discharge from different drains (industrial, agricultural, and municipal wastes) and the industrial region in Port Said, respectively. The lower HM concentrations from the extreme northern parts (Al-Boghaz [S2], Al-Temsah [S4], Al-Hamra [S7], and Al-Kowar [S9]) were due to their isolation from urban areas compared with the other localities. Extensive waste disposal was responsible for the HM pollution in the Manzala Lake sediments. Advanced treatment technologies and monitoring of the pollution in the water and sediments of Manzala Lake are required to decrease the accumulation of the heavy metals.

Evaluation of the ecological health and food chain on the shores of four River Nile Islands, Egypt.

This study was conducted to evaluate the impact of human activities on the ecological health and food chain at the shores of four Nile Islands in Great Cairo including El-Qeratten, El-Waraq, El-Zamalek, and El-Manial. Water quality, bacteria, phytoplankton, benthic algae, zooplankton, macrobenthic invertebrates, and bony fishes were examined at each island shore over two seasons including the lowest and the highest flow (February and July 2020, respectively). The obtained results showed that the average values of most of the chemicals in Nile Island's water were within the Egyptian water quality limits. Discriminant analysis of physicochemical factors revealed a similarity between El-Waraq and El-Qerateen and between El-Manial and El-Zamalek. El-Qeratten was the most polluted island. It has the highest total and fecal coliform bacteria count (3.155 and 3.050 Log MPN/100 mL, respectively). El-Zamalek shores have the highest phytoplankton (33,582 cells × 104 L-1) and zooplankton count (310,891 organisms × m-3) and phyto-biochemical values. Biochemical analysis of phytoplankton demonstrated the richness of the bulk by protein (> 85% of biomass), indicating that phytoplankton has a high nutritional value. Elevated zooplankton count was recorded at El-Zamalek, which coincided with the peak of phytoplankton abundance. Mollusca were the dominant macrobenthic invertebrates on most of the island's shores. Bony fishes were represented by 27 species and two crustaceans. The levels of the metals in fish samples were compared with the food safety guideline endorsed by the World Health Organization and Food and Agriculture Organization (WHO/FAO) to evaluate the toxicity level.

The Chronic Exposure to Discharges of Sabal Drain Induces Oxidative Stress and Histopathological Alterations in Oreochromis niloticus.

To study whether the effluents of Sabal drain could affect the health status of Oreochromis niloticus; site2 (south part of main canal), site3 (at the canal outlet), site4 (north part of main canal) and site1 (reference site) were selected. Compared to the reference fish, activities of superoxide dismutase and glutathione peroxidase in addition to glutathione reduced and thiobarbituric acid reactive substances concentrations of the gills showed significant (p < 0.05) increase with different levels in all studied sites. Whereas, catalase activities revealed significant (p < 0.05) decrease in all studied sites with maximum decrease in site3. The recorded histopathological lesions were correlated with the distance from discharge point. Gills, liver and kidney of site3 had the worst histopathological conditions based on the frequency of alterations appearance and size of the affected areas. While, the regressive alterations that recorded in site2 and site4 suggest the onset of adaptive histological mechanisms.

Seasonal variation and enrichment of metals in sediments of Rosetta branch, Nile River, Egypt.

This study investigated heavy metal pollution in sediments of the Rosetta branch of the River Nile of Egypt to quantify the toxic distribution potential of metals into the surrounding environment. Sediment samples were collected at 9 sites during in four seasons. Organic matter and total metal concentrations were determined using loss on ignition and inductively coupled plasma spectrometry, respectively. Principal component analysis has been applied to evaluate the metal sources and the relationships between metals in sediments. Metal concentrations showed the following order: winter > autumn > spring > summer. Mean concentrations of Cu, Zn, Cd, and Pb in sediments were above the average background value of metals in shale. Pb and Cd showed higher enrichment during all seasons at stations N3/N4, Zn at stations N1 to N4, and Cu at stations N6/N8. The variations in heavy metal total concentration and organic matter are due to different input sources, physico-chemical conditions, and adsorption/precipitation/redox conditions in sediments. Mean values of Geo-accumulation index (Igeo) for Fe, Mn, and Cu were below 0 which were classified as unpolluted during spring, summer, and autumn, except Cu increased from unpolluted to moderately polluted during winter. Igeo values for Cd, Pb, and Zn increased from unpolluted-moderately polluted to highly-very highly polluted during autumn and winter. Pollution Load Index was recorded in highest values during winter, especially at Fuwwah/Basioun and in lowest values during summer at after the Edfina Barrage/before Kafer El-Zayat due to industrial/human activities. Both natural and anthropogenic sources contributed to the metal accumulations in sediments, and industrial, agricultural, and municipal sewage effluents discharged from non-point sources may be the main anthropogenic sources for metals in the Rosetta branch.