Ecological risk assessment of metal pollution in the surface sediments of delta region, Egypt.

The surface sediments from eleven sectors perpendicular to the Egyptian Mediterranean Sea coast, along the delta region, have been assessed. These sectors cover areas of Eastern Harbour, Abu Qir Bay, Rosetta, Abo Khashaba, Burullus, Baltim, Damietta, and Manzala. The assessment process is based on determining the eight metals' (Fe, Cu, Zn, Mn, Ni, Co, Pb, and Cd) content, followed by applying different pollution and ecological risk indices such as enrichment factor (EF), geoaccumulation factor (Igeo), contamination factor (CF), Pollution Load Index (PLI), degree of contamination (Cdeg.), Nemerow Integrated Pollution Index (NIPI), and Potential Ecological Risk Index (PERI). The results indicate the average concentrations of metals (µg/g) were Fe (18,000), Mn (213), Zn (120), Ni (26), Co (13), Cu (12), Pb (10), and Cd (2). The single-pollution indices reveal that most metals were depleted to metal levels, the sediments were moderately polluted with Cd and unpolluted with other metals, and the CF values confirmed that the sediments were highly polluted with Cd and low contaminated with the rest of the metals. According to the integrated pollution indices, the Eastern Harbour, Damietta, Manzalah, and Bardawil (eastern Inlet) are the most polluted sectors relative to the rest, subjected to various point sources of pollution. Drainage management system is recommended to enhance water conservation and improve fish stocks.

Spatiotemporal distribution of some dissolved salts and minerals in Lake Edku connected to Mediterranean Sea: in relation to different pollutant inputs.

Regarding the generally accepted view of the minerals formed in solving the problem of ecosystem pollution, this research aims to track the role of seasonal minerals in overcoming widespread pollution problems in Lake Edku. At eleven locations inside Lake Edku and three locations in the outside the water inlets, some physical and chemical parameters that affect the formation of minerals and salts were detected seasonally. As a result of human activities from 1972 to 2020, the applied remote sensing technology showed a decrease in the area of Edku Lake by 13.3%. The saturation index (SI) of twelve minerals formed in fifty-six seasonal water samples collected from fourteen locations inside and outside the lake was estimated. The saturation index (SI) of anhydrite (ANH), gypsum (GYP), calcium phosphate (CP), magnesium phosphate (MP), calcite (CAL), aragonite (ARG), dolomite (DOL), magnesite (MGS), fluorapatite (FAP), hydroxyapatite (HAP), octacalcium phosphate (OCP), and carbonate-fluorapatite (CFAP) was calculated. The presented SI values of apatite and phosphate minerals including FAP (SI 30.63-65.65), CFAP (SI 28.14-40.02), HAP (SI 24.83-31.81), Ca3(PO4)2 (SI 23.99-25.95), OCP (SI 19.96-25.47), and Mg3(PO4)2 (SI 15.80-17.46) were high. Palmer-Roger's diagram and piper ternary diagram models reflected the abundance of NaCl in lake water with 30, 40, 46, and 75% in winter, spring, summer, and autumn, respectively. Using correlation matrix, multiple stepwise regression and cluster analysis for statistical analysis, the relationship between sedimentary minerals and outflow and drainage, as well as the role of sedimentary minerals in reducing pollution in the lake area, was outlined.

Desalination using modified configuration of supported liquid membrane with enhancement of mass transfer of NaCl.

Supported liquid membranes (SLM) suffer from very slow mass transfer of the solute from the donor phase (DP) to the receptor phase (RP) through the liquid membrane (LM). In the present work, an attempt was made to accelerate the mass transfer in SLM by creating a modified configuration in which the DP and RP are made to flow either co- or counter-currently to each other. Variables, which could affect the removal of NaCl, were the volume ratio of DP to RP, type and quantity of sequestering agent (SA), presence of mobile carrier (MC), type of LM, and flow rate of DP and RP. The results showed that the higher the flow rate of DP and RP, the higher the mass transfer of NaCl. Quantity and type of SA and type of LM were prime important factors. Remarkably, the time required for transfer of NaCl from DP to RP was reduced from several hours in the case of stagnant SLM to several minutes in the present work. The mass transfer of NaCl was analysed based on kinetic laws of two consecutive irreversible first-order reactions. The values achieved establish the process is diffusion controlled, and the membrane entrance rate constants increase directly with initial concentration (Ci) and inversely with quantity of SA.

Modeling adsorption kinetic of crystal violet removal by electrocoagulation technique using bipolar iron electrodes.

This paper studies the removal of crystal violet (CV) dye by electrocoagulation (EC) process using bipolar iron electrodes. Numerous operating parameters such as initial CV solution concentration, speed of agitation, number of electrodes, type and quantity of supporting electrolyte, temperature- and initial pH were investigated. A complete removal of 10 mg/L CV was achieved within 10 min at pH 7, 0.5 g NaCl, 1 LCV, 750 rpm, 9 sheets, 17.36 mAcm2, and 25 °C. The performed energy-dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) analyses confirmed the adsorption of CV onto the insoluble iron hydroxide flocs. Amongst the studied adsorption isotherms models, Langmuir and Dubinin-Radushkevich were the most applicable. The kinetic of adsorption of CV onto flocs during the EC operation was studied using the pseudo-first-order, pseudo-second-order, and intraparticulate diffusion models, with results affirming that the adsorption process proceeded according to the pseudo-second-order model. The study of thermodynamic parameters (ΔG0, ΔH0, and ΔS0,) of the CV removal at different temperatures reflected the feasibility of the spontaneous randomness of endothermic adsorption, especially at lower temperatures. The multiple regression equation of the removal of CV by EC technique under the different studied conditions was predicted.

Sedimentology, geochemistry, pollution status and ecological risk assessment of some heavy metals in surficial sediments of an Egyptian lagoon connecting to the Mediterranean Sea.

Spatial distribution of heavy metals (Co, Cu, Ni, Cr, Mn, Zn and Fe) was studied on Lake Edku's surface sediments in relation to sedimentology and geochemistry characteristics and their contamination status on the ecological system. Lake Edku's sediments were dominated by sandy silt and silty sand textures and were enriched with carbonate content (9.83-58.46%). Iron and manganese were the most abundant heavy metals with ranges of 1.69 to 8.06 mg g(-1) and 0.88 to 3.27 mg g(-1), respectively. Cobalt and nickel showed a harmonic distribution along the studied sediments. The results were interpreted by the statistical means. The heavy metal pollution status and their ecological risk in Lake Edku was evaluated using the sediment quality guidelines and the contamination assessment methods (geoaccumulation, pollution load and potential ecological risk indices, enrichment factor, contamination degree as well as effect range median (ERM) and probable effect level (PEL) quotients). Amongst the determined heavy metals, zinc had the most ecological risk. Overall, the heavy metals in surface sediments showed ecological effect range from moderate to considerable risk, specially, in the stations in front of the seawater and in drain sources that had the highest toxic priority.

Levels, distribution, and risk assessment of organochlorines in surficial sediments of the Red Sea coast, Egypt.

The analyses of environmentally persistent pollutants like polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH) isomers, and dichlorodiphenyltrichloroethane (DDT) and its metabolites in surficial sediment samples collected from 17 locations along with the coast of the Red Sea in Egypt were carried out using gas chromatography-mass spectrometry. Several potential organic contaminants from agricultural (e.g., DDT and its breakdown products, lindane, endrin, dieldrin, and endosulfan) and industrial (PCBs) sources were measured. The levels of 20 organochlorine pesticides (OCPs) and ten PCB congeners in sediment collected from 17 stations along ~1,200 km were investigated. Concentrations of PCBs, HCHs, DDTs, and cyclodienes ranged from 0.40 to 6.17, 0.01 to 0.09, n.d. to 0.46, and 0.08 to 0.90 ppb dry weight. Two statistical programs were applied on the data (principal component analysis, PCA, and cluster analysis, CA), and it was concluded that it is impossible to predict the distribution patterns of the OCPs in a contaminated area. Risk assessment of the organochlorines contaminated in the sediments of the studied area was investigated.