Chemical compositions and heavy metal contents of Oreochromis niloticus from the main irrigated canals (rayahs) of Nile Delta

AbstractThe present study aimed to assess the seasonal variations of the proximate chemical composition, physicochemical, microbiological aspects and heavy metal concentrations of Oreochromis niloticus muscles collected from The Nile rayahs from spring 2014 to winter 2015. Rayahs are the main irrigated canals of Nile Delta, Egypt and represent El Tawfiki, El Menoufy, El Behery, and El Nasery rayahs. Results showed a spatial and temporal significant difference (p<0.01) in the proximate composition and Physicochemical aspects of O. niloticus muscles. The moisture, protein, fat, ash, carbohydrates and calorific values varied between (78.55–80.77%), (16.10–17.88%), (1.10–1.95%), (0.55–1.50%), (0.10–0.94%) and (78.37–89.73%), respectively. Heavy metal accumulation in the O. niloticus muscles showed irregular distributions with descending order of: Fe>Zn>Mn>Cu>Pb>Cd. Generally, heavy metals, TVB-N, TMA, TBA and TVC did not exceed the maximum permissible limits in the tissues of O. niloticus. The values of Hazard Index (HI) and Hazard Quotient (HQ) are lower than the acceptable limits, which indicate that the metals in O. niloticus in the Nile rayahs, Egypt, do not pose any particular human health risk concern. Therefore, O. niloticus muscles collected from four rayahs are safe for human consumption and could be used as a source of healthy diet for humans

Comprehensive Insight into Lake Nasser Environment: Water Quality and Biotic Communities—A Case Study before Operating the Renaissance Dam

This study focused on the monitoring and assessment of aquatic ecosystem functioning based on the abiotic and biotic features of Lake Nasser in the post-flood and pre-flood periods as the last ones before water storing behind the Grand Ethiopian Renaissance Dam. The physicochemical parameters, distribution and structure of biotic communities, including bacteria, phytoplankton, zooplankton, macrophytes, epiphytes and fish were analyzed at 15 sites. The values of most parameters (primarily temperature, total suspended solids, pH, orthophosphates, carbonates, sulphates and some cations) were higher in the pre-flood period, whereas higher values of conductivity, total dissolved solids, total solids, nitrites, nitrates, chemical oxygen demand, bicarbonates and chlorophyll a were recorded in the post-flood period. Cyanobacteria-dominated phytoplankton and total coliform bacteria were more abundant in the pre-flood period, and especially at sites 10–15, whereas higher abundances of zooplankton were recorded in the post-flood period. All these changes in parameters were significantly differentiated, and only the concentrations of dissolved oxygen, biochemical oxygen demand, ammonium and silicates were at similar level in both periods. The study also indicated that environmental factors had affected the macrophyte distribution and the adaptation of the invasive species Myriophyllum spicatum to thrive under different environmental factors in the lake. Besides, macrophytes provided the habitat to other aquatic organisms, especially epiphytes, and also helped maintaining the good water quality, nutrient cycling and stabilizing rivers’ and lakes’ banks. Generally, these conditions were rather favorable for biological processes and fish production

Selective genotyping using genome wide association studies for mapping loci associated to fiber diameter in Merino sheep

The objective of this study was to investigate methods and statistical power for mapping quantitative trait loci (QTL) using selective genotyping and Illumina's 50K BeadChip. A large unrelated population is recorded for a phenotypic trait. Animals with extreme phenotypes are used for genotyping with Illumina's arrays and QTL are mapped by linkage disequilibrium (LD). We carried out computer simulations to compute statistical power using this approach after varying QTL allele frequency, proportion selected in the extremes, and population size. For example, power for a population of 1,000 animals after genotyping the top and bottom 5% (QTL effect of 0.5 phenotypic standard deviations, alpha of 0.01 and allele frequency of 0.1) and assuming maximum LD, was 0.95. The method was tested in a Merino flock with 979 ewes in which fiber diameter (FD) was recorded. Illumina's 50K Bead Chip was used for simultaneous genotyping of 54,241 SNPs in selected animals (24 in each extreme) but only within a year class and breed. A total of 208 tests were significant out of 18,214 SNPs tested at significance level of 0.01. There were more significant tests than expected by chance. The highest significant results were obtained in Chromosomes 1, 14, 15, 21 and 26. Validation of the results must be confirmed in the unselected population

Novel Combined Toxicity Indices (CTI) to assess the ecological risk of metals in sediments dependent on fractions and total metal content, application on Qarun Lake sediment, case study

Fractions and total contents of 21 heavy metals were evaluated in Qarun Lake sediment, a closed and shallow turbid saline lake. The metal contents in the sediments were in the following order: Fe > Al > Ti > Mn > Sr > Zn > Cr > Pb > Ba > Ni > B > Cu > Li > Co > As > Ga > Cd > Se > Bi > Ag > Hg. Several indices based on the total content (T-indices) or the fraction ratios (F-indices) assessed the pollution degree of the sediment. All the indices used revealed that the sediment of Qarun Lake suffers from different degrees of metal pollution. The T-indices evaluate the pollution or potential risk depending on the total content of metals, regardless of the species of these metals (hazardous mobile or non-mobile forms). Also, the F-indices evaluate pollution depending on the fraction ratios of metals, regardless of their metal content (even if at a deficient level). This study suggested a new combined toxicity index (CTI) and mean CTI (m-CTI) to combine T-indices and F-indices to assess the potential toxicity of metals and the pollution levels of sites, respectively. Based on integrated T-indices, all selected sites in Qarun Lake were extremely or highly polluted. Also, the GCF (as F-index) revealed that the investigated metals highly contaminated all sites. In contrast, according to the m-CTI, sites 1, 3, and 4 were highly polluted, while sites 2, 5, and 6 were moderately polluted. The present study's findings indicate that using CTI and m-CTI may be more favorable and accurate in assessing the metal pollution status of sediment than using T-indices or F-indices separately

Nutrient status and Phosphorus speciation of Manzalah Lake sediment, Egypt

EnManzalah Lake is largest brackish water ecosystem (~1071 km2) in the Mediterranean delta coast of Egypt. This study aims to determine the spatial and temporal distribution of nutrient, nitrogen (N) and phosphorus (P) and their forms, in the sediment of Manzalah Lake. Ammonia was the dominant nitrogen forms (188.57 ± 82.62 μg g-1) followed by nitrate (5.51 ± 4.30 μg g-1). The total P concentrations ranged from 817.2 μg g-1 to 1912.6 μg g-1 with a mean value of 1134.9 ± 240.86 μg g-1. The rank order of P fractions in Manzalah Lake sediment was different among seasons, where the most abundant form was NaOH-P that participated with high percentage (average: 48.39%). Inorganic-P participated with a major fraction in formation of sedimentary phosphorus, amounting to 56.25 %. The order of inorganic P fractions was: Al-P> Ca-P > Fe-P > available-P with their average relative abundances of 8.60: 3.62: 1.93: 1.00. The sediments play an important role in the dynamic sink-source of nutrients, modifying the nutrient availability in water column. Abiotic factors such as salinity, pH and temperature, and functional ecosystem processes such as primary production and decomposition, can affect significantly the phosphorus concentration in the surface lake sediment more than external factors such as the sewage inputs in the transitional water ecosystems

Preparation and characterization of graphene – TiO2 nanocomposite for enhanced photodegradation of Rhodamine-B dye

The synthesizing of TiO2@rGO nanocomposites using an efficient method has been carried out to enhance the photodegradation activities of TiO2. Reduced graphene oxide (rGO) synthesis has been illustrated as a key step. The preparation of TiO2@rGO is highly needed and recommended to develop an effective way for the reduction of GO. Our study illustrated an environmentally simple method for TiO2@rGO preparation and demonstrated its efficiency for photocatalytic process by utilizing rhodamine-B dye as an organic pollutant. Synthesized nanoparticles of reduced TiO2@rGO have an observable increase in photo-energy adsorption leading to the increase of the photodegradation reactions. From the obtained results, TiO2@rGO nanocomposites showed great ability to absorb photo-energy and enhance the photodegradation reactions. Moreover, the results revealed that the 3% TiO2@rGO have the best performance than 1% TiO2@rGO at pH = 9.0, 30 mg/l initial dye concentration and 60 min irradiation duration. The reduced graphene oxide production was considered as an influential co-catalyst for improving the TiO2 photocatalytic activities mainly owing to; the fast separation of h+/e− and the adsorption improvement. Our study affirms the production of promising applicable particles using the environmental photocatalysis process in particular with regard to wastewater purification. Keywords: Photocatalysis, TiO2, Graphene oxide, Nanocomposite, XRD, Rh-B dye, TE

Indices of water quality and metal pollution of Nile River, Egypt

Nile River is the valued natural and exclusive source of fresh water in Egypt, where the drinking water supply is limited to the river. The water quality of 24 sites between Aswan and Cairo along the Nile was investigated. To evaluate the suitability of water for aquatic life and drinking purposes, the indices of water quality (WQI), heavy metal pollution (HPI) and contamination (Cd) were computed. The water quality variations were mainly related to inorganic nutrients and heavy metals, where, the sites affected by intensive load of urban, agricultural and industrial wastewater showed serious deterioration of water quality compared with other sites. The anthropogenic impact sites showed high HPI and Cd values and associated with high risks, where, most of the studied metals often exceeded the drinking water and aquatic life limits. The aquatic WQI indicated that the Nile water quality deteriorated and extended from poor to marginal, while drinking WQI varied from marginal to good. Accordingly, the river becoming unfit for aquatic life and the situation is getting worse by decreases in the water budget from the Nile in Egypt by building of the Grand Ethiopian Renaissance Dam, where the dilution strength of the Nile system will reduce

Metal pollution assessment in the surface sediment of Lake Nasser, Egypt

Eight heavy metals were measured seasonally in the sediment of Lake Nasser during 2013. 27 sites were chosen through 9 sectors across the main channel of the lake from Abu-Simbel to Aswan High Dam to assess the levels of the selected metals. The abundance of these metals was in the order of Fe > Mn > Zn > Cr > Ni > Cu > Pb > Cd, with mean concentrations of 12.41 mg/g, 279.56, 35.38, 30.79, 27.56, 21.78, 11.21 and 0.183 μg/g, respectively. Heavy metals are positively correlated with fine particles (mud fractions) and organic matter accumulation. The results showed perspicuous spatial high significant differences (P < 0.01) for all the measured metals. Fe, Cr, Ni, Pb and Cd exhibited temporally high significant differences (P < 0.01) before and after the flood period. Four Pollution Indices were used for the environmental assessment of Lake Nasser sediment. The indices included three single indices, Enrichment Factor (EF), Index of Geo-accumulation (Igeo) and Contamination Factor (CF). While the fourth, Pollution Load Index (PLI) was an integrated index. The pollution indexes confirmed that the Lake Nasser sediment was not contaminated with these elements. Sediments of Lake Nasser may be represented as a reference for the pre-industrial background of River Nile Sediments downstream Aswan High Dam

Assessment of heavy metal pollution in water and its effect on Nile tilapia (Oreochromis niloticus) in Mediterranean Lakes: a case study at Mariout Lake

Abstract Mariout Lake is one of the Northern Nile-Delta Lakes in Egypt that receives agricultural, industrial and domestic effluents through several drains. The present study aims to evaluate the levels of some heavy metals (HMs) in water and edible parts of Oreochromis niloticus in Mariout Lake, in addition to studying several pollution indices and potential human health risks. The levels of the studied HMs in water were in the order of Fe > Zn > Mn > Pb > Cu > Ni > Cd. However, results of the pollution index, that concerns the effect of individual metal, concluded that Cd and Pb in water had serious pollution effects for aquatic life, while Cu, Fe, Mn, Ni, and Zn had not any pollution effects at different locations in the lake. The indices of the composite effects of all HMs (Metal Index and Heavy Metal Pollution Index) indicated the high pollution of Mariout Lake water, which may cause adverse effects on fish and different aquatic organisms. On the other side, the bioaccumulation factors of HMs in edible parts of O. niloticus were in the order of Zn > Cd > Cu > Ni > Pb > Mn > Fe. Although the target hazard quotient for all metals was less than the non-hazardous limit (THQ < 1), the non-carcinogenic hazard index (HI = 1.24) was classified in the moderate hazard risk level (1 < HI < 10) indicating low potential adverse effects on the exposed population due to consumption of O. niloticus caught from Mariout Lake

Removal of aluminum, iron and manganese ions from industrial wastes using granular activated carbon and Amberlite IR-120H

The removal of aluminum, iron and manganese from some pollution sources that drain into Ismailia Canal has been investigated using two different sorbents; granular activated carbon (GAC) and Amberlite IR-120H (AIR-120H). Batch equilibrium experiments showed that the two sorbents have maximum removal efficiency for aluminum and iron pH 5 and 10 min contact time in ambient room temperature, while pH 7 and 30 min were the most appropriate for manganese removal. Dosage of 2 g/l for both GAC and AIR-120H was established to give the maximum removal capacity. At optimum conditions, the removal trend was in order of Al+3 > Fe+2 > Mn+2 with 99.2, 99.02 and 79.05 and 99.55, 99.42 and 96.65% of metal removal with GAC and AIR-120H, respectively. For the three metals, Langmuir and Freundlich isotherms showed higher R2 values, with a slightly better fitting for the Langmuir model. In addition, separation factors (RL) and exponent (n) values indicated favorable Langmuir (0 < RL < 1) and Freundlich (1 < n < 10) approach. GAC and AIR-120H can be used as excellent alternative, effective and inexpensive materials to remove high amounts of heavy metals from waste water