Physicochemical characteristics and distribution of some metals in the ecosystem of Lake Nasser, Egypt

Environmental assessment of physical-chemical features of Lake Nasser, Egypt

Lake Nasser is one of the largest man-made lakes on earth. It has a vital importance to Egypt for several decades because of the safe water supply of the country. Therefore, the water quality of the Lake Nasser must be profoundly investigated, and physico-chemical parameter changes of the water of the Lake Nasser should be continuously monitored and assessed. This work describes the present state of the physico-chemical (nitrate-nitrogen, nitrite-nitrogen, orthophosphate, total phosphate content, dissolved oxygen content, chemical oxygen demand, and biological oxygen demand) water parameters of Lake Nasser in Egypt at nine measurement sites along the Lake Nasser. The algorithm was devised at the University of Pannonia, Hungary, for the evaluation of the water quality. The aquatic environmental indices determined alongside the Lake Nasser fall into the category of "good" water quality at seven sampling sites and exhibited "excellent" water quality at two sampling sites according to Egyptian Governmental Decree No. 92/2013. In light of the tremendous demand for safe and healthy water supply in Egypt and international requirements, the water quality assessment is a very important tool for providing reliable information on the water quality. The protocol for water quality assessment could significantly contribute to the provision of high-quality water supply in Egypt. In conclusion, it can be stated that the parameters under investigation in different regions of Lake Nasser fall within the permissible ranges and the water of the Lake has good quality for drinking, irrigation, and fish cultures according to Egyptian standards; however, according to European specifications, there are steps to be accomplished for future water quality improvement.

Contamination and Ecological Hazard Assessment of Heavy Metals in Freshwater Sediments and Oreochromis niloticus (Linnaeus, 1758) Fish Muscles in a Nile River Canal in Egypt

Heavy metal residues in sediment and Oreochromis niloticus fish muscles, collected from a Nile River Canal (Bahr Shebeen Canal), Egypt, were investigated from September 2014 to December 2015. The spatial and seasonal distributions of Cd, Cu, Fe, Pb, and Zn are described and discussed. Relative abundance of these metals in sediment was found as follows: Fe > Zn > Cu > Pb > Cd. Indices of pollution were used to detect the degree of sediment contamination and indicated elevated concentrations likely to adversely affect benthic and benthic-associated organisms. Anthropogenic activities strongly influenced metal occurrence in sediments. Accumulation of heavy metals in fish muscular tissue was found to be nearly comparable to the sediment. Relative abundance of metals in fish tissue followed the trend of Fe > Zn > Pb > Cu > Cd. Fish can be used as a surrogate for heavy metals pollution. The bioaccumulation factor (BAF) in fish muscle showed the following trend: Pb > Zn > Cu > Fe > Cd. Levels of most selected heavy metals detected in muscular tissue of fish were below admissible limits set by different organizations. However, HI (hazard index) showed that the cumulative risk effects are of considerable concern, especially where fish consumption is high. Consequently, it is recommended that discharged water containing pollutants should be prioritized to include continuous monitoring, and adequate public awareness.

Assessment of metal contamination in water, sediment, and tissues of Arius thalassinus fish from the Red Sea coast of Yemen and the potential human risk assessment

Heavy metal pollution is one of the most serious environmental issues globally. To evaluate the metal pollution in the Red Sea coast of Hodeida, Yemen Republic, the concentrations of Fe, Cu, Ni, Pb, and Cd in water, sediment, and some vital organs of sea catfish, Arius thalassinus collected from polluted and unpolluted sites, were determined. The risk of these metals to humans through fish consumption was then assessed. The results showed that the concentration order of metals in water, sediment, and fish tissues were Fe > Cu > Ni > Pb > Cd. The levels of studied metals in water, sediment, and fish tissues were significantly higher in the polluted site than those of the unpolluted site, with few exceptions. Linear correlation incorporating paired variables (water-sediment, water-fish, and fish-fish) exhibited several significant correlations indicating a common metal pollution. The risk assessment performed revealed that fish consumption was safe for consumers. This field investigation provides a baseline data on metal pollution in this region.

Occurrence, distribution, and ecological risk assessment of potentially toxic elements in surface sediments of Lake Awassa and Lake Ziway, Ethiopia

Microwave-assisted acid digestion and modified aqua regia (HNO3:HCl:HF:H3BO3) leaching techniques were used for the determination of 15 potentially toxic elements (V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Ag, Cd, Sn, Hg and Pb) in sediment samples from Lake Awassa and Lake Ziway, Ethiopia. The digests were subsequently analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES). Mercury was directly determined in the solid samples using an elemental mercury analyzer. The precision and accuracy of the digestion procedures were verified using certified reference materials. The experimental results were in good agreement with the certified values (P < 0.05) and the recoveries were quantitative (>90%). The average relative standard deviations were below 10%. There is significant correlation between the two lakes at the 0.01 level (2-tailed). Using the sediment quality guidelines, both lakes are heavily polluted with Zn and some of the sites are heavily polluted with Cu, Ni and Pb. Based on effect range low (ERL) - effect range medium (ERM), in both lakes for Ag were greater than the ERM, indicating that the areas could be toxic to aquatic organisms, while for Cr, Cu, As and Hg the values were less than ERL.

Seasonal variability in cadmium, lead, copper, zinc and iron concentrations in the three major fish species, Oreochromis niloticus, Lates niloticus and Rastrineobola argentea in Winam Gulf, Lake Victoria: impact of wash-off into the lake

Trace metals Cadmium (Cd), Lead (Pb), Copper (Cu), Zinc (Zn) and Iron (Fe) were analyzed in edible portions of three main finfish species namely Lates niloticus, Oreochromis niloticus and Rastrineobola argentea sampled from various beaches of Winam Gulf, Lake Victoria, Kenya, in order to determine any seasonal and site variations and the results showed significantly (p < 0.05) higher mean concentrations of Cd, Cu, Zn and Fe during the wet season compared to the dry season for all the three species indicating the impact of wash-off into the lake during the rainy periods. The overall mean concentrations of the heavy metals (in μg/g dry weight) in all combined samples ranged from 0.17-0.40 (Cd), 0.47-2.53 (Pb), 2.13-8.74 (Cu), 28.9-409.3 (Zn) and 31.4-208.1 (Fe), respectively. It was found that consumption of Rastrineobola argentea can be a significant source of heavy metals especially Zn, to humans, compared with Lates niloticus and Oreochromis niloticus, if only the muscle parts of the latter two are consumed.

Distribution and partitioning of iron, zinc, and arsenic in surface sediments in the Grande River mouth to Cuitzeo Lake, Mexico

Cuitzeo Lake is one of the largest and most important lakes in Mexico. It receives different types of pollutants through its main tributary, the Grande River of Morelia. The aim of this work was to determine if high concentrations of iron, zinc, and arsenic are present in sediments in an area near the river mouth to the lake, as well as to estimate the partitioning of these metals using a sequential extraction procedure in order to obtain information of their potential bioavailability. Sediment samples were collected from three different sites in Cuitzeo Lake and two sites in Grande River in both dry and wet seasons. A sequential extraction procedure was carried out to determine the concentrations of these elements in different geochemical phases of the sediments. Total metal concentrations were evaluated by using the enrichment factor and the geoaccumulation index. A comparison with sediment quality guidelines and shale values has also been made. The results indicate that sediments are considered unpolluted by iron and moderately polluted by zinc and arsenic. However, fractionation studies showed that significant amounts of Zn and As could be released to the lake ecosystem depending on the environmental conditions, representing a medium risk potential of bioavailability to the biota.