Ecological structure of aquatic macroinvertebrate communities in the Hauts Plateaux of Northeast Algeria

Abstract Aquatic macroinvertebrates are integral parts of functioning wetlands, inhabiting a diversity of aquatic ecosystems where communities are spatially structured. Macroinvertebrates of some Mediterranean regions such as North Africa are still not well studied. Here, we study the community structure of benthic macroinvertebrates in four different types of lotic and lentic wetlands in the semiarid Haut Plateaux of Northeast Algeria. Macroinvertebrates and 06 physicochemical parameters were sampled in 12 sites belonging to four types of habitats (lotic river, lentic river, dams, and sebkha [saline lentic water body]) during January-December 2021. Eventually, the character lentic-lotic was the most important variable affecting the affecting invertebrate communities in the Mediterranean region. The results revealed that sebkha and dams had a lower Shannon index than lentic and lotic rivers. Non-metric multidimensional scaling analysis showed a strong overlap between the community composition in lotic and lentic sites . Howeverin the three types of aquatic groups lentic river, dam and lotic habitats showed a strong overlap between the community whereas sebkha was markedly separated. Redundancy analysis showed that water velocity and pH, were the main drivers of community structure of macroinvertebrates, revealed a strong effect with pH (F1,8=4.15, P = 0.001) and water velocity (F1,8= 3.22, P = 0.002) , separating lotic communities from those that inhabited dams, lentic rivers, and sebkhas. As conclusion, this study contributes to the better understanding of the community structure of macroinvertebrates in semiarid North Africa where wetlands have been experiencing high anthropogenic disturbance

Characterization of CoCr2O4 semiconductor: A prominent photocatalyst in the degradation of basic blue 41 from wastewater

International audienceThe hazards of dyes on the water have driven researchers to develop strategies to remove them. Our choice for this study was photocatalysis. In view of this, semiconductor CoCr2O4 (CCO) by the co-precipitation method was synthesized and explored for its photo-catalytic efficiency by the possible elimination of basic blue 41 (BB41) by degradation in the visible light irradiation. The phase of synthesized CCO was refined and characterized structurally using X-ray diffraction (XRD) associated with the Rietveld method to illustrate the structural form of this spinel. The characteristic bands of CCO were identified for the vibrational groups using the FT-IR spectrum. Using the diffused reflectance data, an optical gap band of 1.65 eV was determined. The energy diagram resulting after the electrochemical study confirmed that the catalyst adopts the nature of n-type semiconductors. The photocatalytic degradation of BB41 by CCO as a function of time of irradiation, pH of BB41 solution, CCO dose and initial BB41 concentration was determined. The degradation percentage of 99% was studied for. 300 min but the efficiency decreased as the initial dye concentration was decreased. The photo-degradation mechanism and the compliance of pseudo-first-order models are discussed in this contribution. © 2021 Elsevier B.V

Photocatalytic performances of ZnCr2O4 nanoparticles for cephalosporins removal: Structural, optical and electrochemical properties

International audienceThe present contribution is about the synthesis of a composite photo-catalyst with remarkable activity and a narrow gap band to explore the possibility of using it for the removal of antibiotics in water. The synthesis of spinel ZnCr2O4 (ZCO) nanoparticles in pure phase by the combination of sol-gel methodology at 700 °C was achieved. The identification and characterization were done using characterization studies such as X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and UV–Visible spectroscopy techniques. The illustration of spinel structure was done with the help of lattice constants using XRD data. The optical and dielectric properties of ZCO were measured using the UV–Visible data. The photo-electrochemical property revealed the flat band potential value of 0.3 VSCE which ascribes the n-type semiconductor. The photocatalytic activity of ZCO nanoparticles under visible light source in degrading the three pharmaceutical products such as Cefaclor (CFR), Cefuroxime (CFRM) and Cefixime (CFX) of 66.9%, 55.2% and 80.1% was also successfully studied. © 2021 Elsevier B.V

Bismuth Sillenite Crystals as Recent Photocatalysts for Water Treatment and Energy Generation: A Critical Review

International audiencePhotocatalysis has been widely studied for environmental applications and water treatment as one of the advanced oxidation processes (AOPs). Among semiconductors that have been employed as catalysts in photocatalytic applications, bismuth sillenite crystals have gained a great deal of interest in recent years due to their exceptional characteristics, and to date, several sillenite material systems have been developed and their applications in photoactivity are under study. In this review paper, recent studies on the use of Bi-based sillenites for water treatment have been compiled and discussed. This review also describes the properties of Bi-based sillenite crystals and their advantages in the photocatalytic process. Various strategies used to improve photocatalytic performance are also reviewed and discussed, focusing on the specific advantages and challenges presented by sillenite-based photocatalysts. Furthermore, a critical point of certain bismuth catalysts in the literature that were found to be different from that reported and correspond to the sillenite form has also been reviewed. The effectiveness of some sillenites for environmental applications has been compared, and it has demonstrated that the activity of sillenites varies depending on the metal from which they were produced. Based on the reviewed literature, this review summarizes the current status of work with binary sillenite and provides useful insights for its future development, and it can be suggested that Bismuth sillenite crystals can be promising photocatalysts for water treatment, especially for degrading and reducing organic and inorganic contaminants. Our final review focus will emphasize the prospects and challenges of using those photocatalysts for environmental remediation and renewable energy applications. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

A review of the use of semiconductors as catalysts in the photocatalytic inactivation of microorganisms

International audienceObtaining clean and high-quality water free of pathogenic microorganisms is a worldwide challenge. Various techniques have been investigated for achieving an effective removal or inacti-vation of these pathogenic microorganisms. One of those promising techniques is photocatalysis. In recent years, photocatalytic processes used semiconductors as photocatalysts. They were widely studied as a green and safe technology for water disinfection due to their high efficiency, being non-toxic and inexpensive, and their ability to disinfect a wide range of microorganisms under UV or visible light. In this review, we summarized the inactivation mechanisms of different waterborne pathogenic microorganisms by semiconductor photocatalysts. However, the photocatalytic efficiency of semiconductors photocatalysts, especially titanium dioxide, under visible light is limited and hence needs further improvements. Several strategies have been studied to improve their efficiencies which are briefly discussed in this review. With the developing of nanotechnology, doping with nanomaterials can increase and promote the semiconductor’s photocatalytic efficiency, which can enhance the deactivation or damage of a large number of waterborne pathogenic microorganisms. Here, we present an overview of antimicrobial effects for a wide range of nano-photocatalysts, in-cluding titanium dioxide-based, other metal-containing, and metal-free photocatalysts. Promising future directions and challenges for materials research in photocatalytic water disinfection are also concluded in this review. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Superior removal of dyes by mesoporous MgO/g-C(3)N(4) fabricated through ultrasound method: Adsorption mechanism and process modeling

International audienceThe present research concerns the synthesis of a mesoporous composite characterized with high surface area and superior adsorption capacity in order to investigate its efficacity in removing hazardous and harmful dyes molecules from water. The synthesized mesoporous composite, MgO/g-C(3)N(4) (MGCN), was successfully prepared through the sonication method in a methanolic solution followed by an evaporation and a calcination process. The configuration, crystalline phase, surface properties, chemical bonding, and morphological study of the fabricated nanomaterials were investigated via XRD, BET, FESEM, HRTEM, XPS, and FTIR instrumentation. The obtained nanomaterials were used as sorbents of Congo Red (CR) and Basic Fuchsin (BF) dyes from aqueous solutions. Batch elimination experimental studies reveal that the elimination of CR and BF dyes from an aqueous solution onto the MGCN surface was pH-dependent. The highest removal of CR and BF pollutants occurs, respectively, at pH 5 and 7. The absorptive elimination of CR and BF dyes into the MGCN surface was well-fitted with a pseudo-second-order kinetics and Langmuir model. In this concern, the maximum nanocomposite elimination capacity for CR and BF was observed to be 1250 and 1791 mg g(-1), respectively. This investigation confirms that MGCN composite is an obvious and efficient adsorbent of CR, BF, and other organic dyes from wastewater

Circulation of a Meaban-like virus in yellow-legged gulls and seabird ticks in the western Mediterranean Basin

In recent years, a number of zoonotic flaviviruses have emerged worldwide, and wild birds serve as their major reservoirs. Epidemiological surveys of bird populations at various geographical scales can clarify key aspects of the eco-epidemiology of these viruses. In this study, we aimed at exploring the presence of flaviviruses in the western Mediterranean by sampling breeding populations of the yellow-legged gull (Larus michahellis), a widely distributed, anthropophilic, and abundant seabird species. For 3 years, we sampled eggs from 19 breeding colonies in Spain, France, Algeria, and Tunisia. First, ELISAs were used to determine if the eggs contained antibodies against flaviviruses. Second, neutralization assays were used to identify the specific flaviviruses present. Finally, for colonies in which ELISA-positive eggs had been found, chick serum samples and potential vectors, culicid mosquitoes and soft ticks (Ornithodoros maritimus), were collected and analyzed using serology and PCR, respectively. The prevalence of flavivirus-specific antibodies in eggs was highly spatially heterogeneous. In northeastern Spain, on the Medes Islands and in the nearby village of L'Escala, 56% of eggs had antibodies against the flavivirus envelope protein, but were negative for neutralizing antibodies against three common flaviviruses: West Nile, Usutu, and tick-borne encephalitis viruses. Furthermore, little evidence of past flavivirus exposure was obtained for the other colonies. A subset of the Ornithodoros ticks from Medes screened for flaviviral RNA tested positive for a virus whose NS5 gene was 95% similar to that of Meaban virus, a flavivirus previously isolated from ticks of Larus argentatus in western France. All ELISA-positive samples subsequently tested positive for Meaban virus neutralizing antibodies. This study shows that gulls in the western Mediterranean Basin are exposed to a tick-borne Meaban-like virus, which underscores the need of exploring the spatial and temporal distribution of this flavivirus as well as its potential pathogenicity for animals and humans