Utilization of aquatic biomass as biosorbent for sustainable production of high surface area, nano- microporous, for removing two dyes from wastewater.

The majority of environmental researchers are becoming increasingly concerned with the manufacture of inexpensive adsorbents for the detoxification of industrial effluents. To address one of the significant and well-known pollution issues with certain drains that act as hotspots and contribute to coastal pollution in Alexandria, this study aims to develop an economical, ecologically friendly sorbent. This study assessed the efficacy of a biomass-coated magnetic composite and a magnetic active adsorbent for the removal of two dyes from an industrially contaminated sewer using a wetland plant (Phragmites australis). Using magnetic biosorbent, the biosorption of Xylenol orange and Congo red ions from polluted drain discharge in Abu Qir Bay was evaluated in the current study. Using scanning electron microscopy imaging and Fourier transform infra-red analysis; the surface function and morphology of the nano-biosorbent were examined. At room temperature, the effects of initial dye concentration, pH, contact time, and nano-biosorbent concentration have all been investigated. The greatest percentages that nano-biosorbent can remove from Congo red and Xylenol orange are 97% and 47%, respectively. The removal of the initial Congo red concentration varied from 42 to 97%, while the removal of the initial Xylenol orange concentration varied from 30 to 47%. The adsorption capacity was shown to be strongly pH-dependent; capacity dose as pH value increased, with pH 10 being the ideal pH for Congo red and pH 6 being the ideal pH value for Xylenol orange. The adsorption capacity for Congo red varied between 0.96 and 3.36 and the adsorption capacity for Xylenol orange varied between 0.18 and 17.58. The removal capacity decreased from 3.36 to 0.96 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L for Congo red, in case of Xylenol orange, the removal capacity increased from 0.18 to 17.58 mg/g when the biosorbent dosage was increased from 0.05 to 0.5 g/L. The removal capacity of Congo red increases quickly with time and varied from 1.66 to 1.88 of contact time; while the removal capacity of Xylenol orange varied between 3.08 and 4.62 of contact time. For the dyes under study, kinetics and adsorption equilibrium were examined. Within 180 min, the equilibrium was attained because to the quick adsorption process. For Congo red and Xylenol orange, the highest adsorption capacities were 3.36 and 17.58 mg g-1, respectively. The equilibrium data were assessed using a number of isotherm models, including Langmuir, Freundlich, BET, and Tempkin, while the kinetic data were examined using a variety of kinetic models, including pseudo-first- and pseudo-second-order equations. The pseudo-second-order equation provides the greatest accuracy for the kinetic data and Langmuir model is the closest fit for the equilibrium data.

Bioaccumulation and biomagnifications of toxic metals in tissues of loggerhead turtles (Caretta caretta) from the Mediterranean Sea coast, Egypt.

Heavy metal concentrations in the different tissues of marine turtles are presented; the most frequently monitored elements are mercury, cadmium, and lead. Concentrations of Hg, Cd, Pb, and As in different organs and tissues (liver, kidney, muscle tissue, fat tissue, and blood) of loggerhead turtle Caretta caretta from the southeastern Mediterranean Sea were determined using Atomic Absorption Spectrophotometer, Shimadzu and mercury vapor unite (MVu 1A) for Hg measurements. The highest levels of cadmium and arsenic were found in the kidney (Cd: 61.17 µg g-1; As: 0.051 µg g-1 dry weight). For lead, the highest level was found in muscle tissue (35.80 µg g-1). Mercury tended to be higher in the liver than in other tissues and organs (0.253 µg g-1 dry weight) which showed a higher accumulation of this element. Fat tissue generally displays the lowest trace element burdens. The concentrations of As remained low in all the considered tissues, possibly the result of low trophic levels in sea turtles. In contrast, the diet of loggerhead turtles would result in significant exposure to Pb. This is the first study into metal accumulation in the tissues of a loggerhead turtle from the Egyptian Mediterranean coastline.

Persistent organochlorine pollutants and metals residues in sediment and freshwater fish species cultured in a shallow lagoon, Egypt.

Six freshwater fish species cultured in Lake Edku fish farm, one of the northern Nile Delta lakes in Egypt that receives input from numerous anthropogenic activities in addition to agriculture wastes through several huge drains, were collected for the detection and evaluation of residues of the persistent organochlorine (OC) pollutants polychlorinated biphenyls (PCBs), 1,1,1 -trichloro-2,2-di(4-chlorophenyl)ethane (DDT), total cyclodienes (TC), hexachlorocyclohexanes (HCHs) and heavy metals (Cu, Cd and Pb) in their edible parts. In all fish and sediment samples, PCBs were found in higher concentrations than pesticides; the edible parts of Mugil capito, Tilapia galilaeus, Tilapia zilli and Clarias lazera had the highest PCBs (3.49, 0.83, 1.06 and 4.29 ng/g wet weight respectively), PCB 28 being most prevalent in Mugilcapito and Clarias lazera with ratios 86 and 62%, respectively, of the total PCBs. PCB 180 was most prevalent in Tilapia zilli (about 56% of the total PCBs). In these four fish species OCs were found in the order: PCBs > DDTs > HCHs > TC. The other two species (Tilapia nilotica and Tilapia aureus) had the highest concentrations of pesticides (7.58 and 1.13 ng/g wet weight, respectively) with HCHs being most prevalent (96% and 74% of the total pesticides, respectively). OCs were found in the order: HCHs >> PCBs > DDTs > TC in the edible Tilapia nilotica, and in the order: PCBs > HCHs > DDTs > TC in the other species. The mean concentrations of PCBs and pesticides in sediments are 539.66 +/- 48.8 and 259.17 +/- 81.2 ng/g dry weight, respectively. Among the studied metals in the edible parts of the fish samples, about 67% of the samples contained marginally higher Pb content in the edible parts, above the European Community's legal limit. About 50% of the samples contained marginally higher Cd content (N.D to 0.88 microg/g) above the permissible level of Cd in fish edible parts; the Cu content ranged from 0.37-2.36 microg/g, with a marginally higher content in the fish but below the maximum permissible limits. As for the concentration of the studied metals in sediments of Edku lagoon, results showed that copper had the highest concentration (2.2 +/- 0.37 microg/g) in the lake sediment.

Bioaccumulation of heavy metals in mollusca species and assessment of potential risks to human health.

Along the Alexandria coast of the Egyptian Mediterranean Sea, five edible species of bivalve molluscs and one gastropoda species (Mactra coralline, Ruditapes decussates, Paphia undulate, Venerupis rhomboids, Crista pectinata and Coralliophila meyendorffi) were analyzed for content of metals (Cadmium, Chromium, Lead, Cobalt and Nickel) in the muscle and in the sediments where they live. The potential health risks of metals to humans via consumption of seafood were assessed by estimated daily intake and target hazard quotient. Significant positive correlations (p < 0.05) were obtained between tissue concentrations for all pairs of metals, with the exception of Cadmium. Significant positive correlations were also obtained for the concentrations of Cd and Ni in tissues of all studied species relative to their concentrations in surface sediments. However, correlations between tissue and sediment concentrations for Chromium, Lead and Cobalt were negative. Ruditapes decussates and C. meyendorffi had the highest values for the summed target hazard quotient and may pose a potential risk to local inhabitants through their consumption in the diet. The potential risk would arise from exposure to high tissue concentrations of Cd and Pb, which exceeded published guidelines for safety of seafood products in some cases. Chromium contributed a considerable fraction of the total target hazard quotient for all metals combined, but did not exceed the published guidelines. Cobalt and Ni did not contribute greatly overall to the target hazard quotient, except in the case of Ni in V. rhomboids.

The potential of different bio adsorbents for removing phenol from its aqueous solution.

The use of natural resources for the removal of phenol and phenolic compounds is being looked upon by researchers in preference to other prevailing methods. In the present study, different biosorbents, brown algae (Padina pavonia), fresh water macrophyta (Ceratophyllum demersum), and black tea residue, were tested as adsorbent for the removal of phenol from aqueous solutions. The optimum conditions for maximum adsorption in terms of concentration of the adsorbate and pH were identified. The results show that the initial concentration increases as the removal of phenol increases in C. demersum; in the case of the other two adsorbents, the initial concentration increases as the removal of phenol decreases, especially for an initial concentration lower than 100 and 1,000 µg/L for P. pavonia and black tea residue, respectively. Maximum percentage removal of phenol by each adsorbent is 77, 50.8, and 29 % for C. demersum, P. pavonia, and black tea residue, respectively. Also, the biosorption capacity was strongly influenced by the pH of the aqueous solution with an observed maximum phenol removal at pH of around 6-10. The first biosorbent (black tea residue) displays the maximum adsorption capacity at a pH of 10 with a percentage sorption capacity of 84 %; P. pavonia revealed a greater adsorption percentage at pH 10, reaching 30 %, while for C. demersum, the removal of phenol increases with the increase in initial pH up to 6.0 and decreases drastically with further increase in initial pH. The Freundlich, Langmuir, and Brauner-Emmet-Teller adsorption models were applied to describe the equilibrium isotherms. The results reveal that the equilibrium data for all phenol adsorbents fitted the Freundlich model which seemed to be the best-fitting model for the experimental results with similar values of coefficient of determination.

Phytoremediation of heavy metals from aqueous solutions by two aquatic macrophytes, Ceratophyllum demersum and Lemna gibba L.

Wetland plants are being used successfully for the phytoremediation of trace elements in natural and constructed wetlands. Under the present investigation, two aquatic macrophytes, Ceratophyllum demersum and Lemna gibba, were tested for their effectiveness at removing two toxic metals (Pb and Cr). These plants were grown at four different concentrations in single-metal solutions of the two metals and were separately harvested after 2, 4, 6, 9 and 12 days in a laboratory experiment. These plants performed extremely well at removing the chromium and lead from their solutions and were capable of removing up to 95% of lead and 84% of chromium during the 12-day incubation period. The removal continued through the 12 days and up to the highest value on the 12th day of the experiment. The results revealed that, of the two species, L. gibba was the most efficient for the removal of selected heavy metals. The plants accumulated heavy metals without the production of any toxicity or reduction in growth.

Ecological risk assessment of heavy metals from the surficial sediments of a shallow coastal lagoon, Egypt.

Sediment quality of Lake Maryout (one of the four Nile Delta shallow brackish water lakes on the south-eastern coast of the Mediterranean Sea) is of concern as this lake is used for land reclamation and aquaculture and is an important fishing source. The magnitude and ecological relevance of metal pollution in Lake Maryout Main Basin was investigated by applying different sediment quality assessment approaches. The aim of this study was to estimate ecological risk of trace elements (Cd, Ni, Pb, Cr, Cu and Zn) in the surficial sediments (<63 jtm fraction) of Lake Maryout. Heavily contaminated sediments were evaluated by the Sediment Quality Guideline (SQG) of the US Environmental Protection Agency. The degree of contamination (Cd) was estimated as very high for each site. Two sets of SQGs effect range-low/effect range-median values and threshold effect concentration (TEC) and probable effect concentration (PEC) values were used in this study. Sediments from each site were judged toxic when more of the PEC values exceeded EPA guidelines. Based on the geoaccumulation index (Ieo) of target trace elements, the Main Basin of Lake Maryout has to be considered as extremely polluted with Cd (Igeo > or =5), strongly polluted with Zn (2 < or = Igeo < or =3), moderately polluted with Cu (1 < or = Igeo < or = 2), unpolluted to moderately polluted with Cr and Pb (0 < or = Igeo < or = 1 for each) and unpolluted with Ni (Igeo < or = 0). Lake Maryout sediments had heavy accumulations of Cd, which apparently come from drains that include industrial and raw domestic wastes. Therefore, a sequential extraction technique was applied to assess the five fractions (exchangeable, metals bound to carbonate, acid-reducible, oxidizable-organic and residual) of Cd in surface sediments. The Cd concentration in most sampling stations was dominated by the non-resistant fraction (anthropogenic). The result showed that those stations located in the vicinity of municipal and mixed waste drains posed a high potential risk to fauna and flora of Maryout Lake.

Potential for internal loading by phosphorus based on sequential extraction of surficial sediment in a shallow Egyptian Lake.

The fractionation of phosphorus (P) in shallow Lake Maryout surficial sediments was investigated in order to understand its potential availability in relation to the eutrophication status of this lake. The rank order of P fractions was NaOH-P > HCl-P > NH(4)Cl-P > BD-P. The metal oxide-bound P (NaOH-P) averaged 43% in this hypereutrophic lake and would be potentially available under low oxygen conditions. The highly available, loosely sorbed P (NH(4)Cl-P) represented 20% of the sedimentary inorganic P on average, while the reductant P (BD-P) averaged 15% and is also considered highly available under low oxygen conditions. The less available calcium-bound P (HCl-P) represented 22% of sedimentary inorganic P. Lake Maryout exhibits high potential for release of P from sediment in forms available to algae, which is undesirable for eutrophication control. The range of potentially available P in tested sediments was 1,541 to 3,990 mg/kg (ppm), a very high quantity capable of supporting algal blooms independent of external loading.

Speciation of trace metals in coastal sediments of El-Mex Bay south Mediterranean Sea-west of Alexandria (Egypt).

Sediments of El-Mex Bay estuary on the southern Mediterranean Sea have been analyzed for trace metals after sediment fractionation by sequential leaching. A sequential extraction procedure was applied to identify forms of Mn, Cu, Cd, Cr, Zn and Fe. The five steps of the sequential extraction procedure partitioned metals into: CH3COONH(4) extractable (F1); NaOAC carbonate extractable (F2); NH(2)OH.HCl/CH(3)COOH reducible extractable (F3); H(2)O(2)-HNO3 organic extractable (F4) and NHO3/HClO4/HF acid soluble residue (F5). Extracted concentrations of trace metals analyzed after all five steps, were found to be (mug/g) for Mn: 1930.2, Cu: 165.3, Cd: 60.9, Cr: 386.3, Zn: 2351.3 and Fe: 10895. Most of elements were found in reducible fraction except Fe found in acid soluble residue, characterizing stable compounds in sediments. Labile (non-residual) fractions of trace elements (sum of the first four fractions) were analyzed because they are more bioavailable than the residual amount. Correlation analysis was used to understand and visualize the associations between the labile fractions of trace metals and certain forms, since Fe-and Mn-oxides play an important role in trace metals sorption within aquatic systems, especially within El-Mex Bay sediments that characterized by varying metal bioavailability.