Marine health of the Arabian Gulf: Drivers of pollution and assessment approaches focusing on desalination activities

The Arabian Gulf is one of the most adversely affected marine environments worldwide, which results from combined pollution drivers including climate change, oil and gas activities, and coastal anthropogenic disturbances. Desalination activities are one of the major marine pollution drivers regionally and internationally. Arabian Gulf countries represent a hotspot of desalination activities as they are responsible for nearly 50% of the global desalination capacity. Building desalination plants, up-taking seawater, and discharging untreated brine back into the sea adversely affects the biodiversity of the marine ecosystems. The present review attempted to reveal the potential negative effects of desalination plants on the Gulf's marine environments. We emphasised different conventional and innovative assessment tools used to assess the health of marine environments and evaluate the damage exerted by desalination activity in the Gulf. Finally, we suggested effective management approaches to tackle the issue including the significance of national regulations and regional cooperation

Potential of novel desert microalgae and cyanobacteria for commercial applications and CO2 sequestration

CO2 fixation by phototrophic microalgae and cyanobacteria is seen as a possible global carbon emissions reducer; however, novel microalgae and cyanobacterial strains with tolerance to elevated temperatures and CO2 concentrations are essential for further development of algae-based carbon capture. Four novel strains isolated from the Arabian Gulf were investigated for their thermotolerance and CO2-tolerance, as well as their carbon capture capability. Two strains, Leptolyngbya sp. and Picochlorum sp., grew well at 40 °C, with productivities of 106.6 ± 10.0 and 87.5 ± 2.1 mg biomass L−1 d−1, respectively. Tetraselmis sp. isolate showed the highest biomass productivity and carbon capture rate of 157.7 ± 10.3 mg biomass L−1 d−1 and 270.8 ± 23.9 mg CO2 L−1 d−1, respectively, both at 30 °C. Under 20% CO2, the biomass productivity increased over 2-fold for both Tetraselmis and Picochlorum isolates, to 333.8 ± 41.1 and 244.7 ± 29.5 mg biomass L−1 d−1. These two isolates also presented significant amounts of lipids, up to 25.6 ± 0.9% and 28.0 ± 2.0% (w/w), as well as presence of EPA and DHA. Picochlorum sp. was found to have a suitable FAME profile for biodiesel production. Both Tetraselmis and Picochlorum isolates showed promising characteristics, making them valuable strains for further investigation towards commercial applications and CO2 capture.The authors would like to thank Mahroof Eroth, Dr. Ahmed Easa, and Dr. Abdulrahman Al Muftah from Qatar University, Andy Selwood from Cawthron Institute, and the QDVC team for their support. This work was supported by QDVC and Qatar University [Project QUEX-CAS-QDVC-14/15-7]

Local Magnetic Properties of a Monolayer of Mn12 Single Molecule Magnets

The magnetic properties of a monolayer of Mn12 single molecule magnets grafted onto a Si substrate have been investigated using depth-controlled $\beta$-detected nuclear magnetic resonance. A low energy beam of spin polarized radioactive 8Li was used to probe the local static magnetic field distribution near the Mn12 monolayer in the Si substrate. The resonance linewidth varies strongly as a function of implantation depth as a result of the magnetic dipolar fields generated by the Mn12 electronic magnetic moments. The temperature dependence of the linewidth indicates that the magnetic properties of the Mn12 moments in this low dimensional configuration differ from bulk Mn12.Comment: 6 pages, 4 figure

Giant Vortices Below the Surface of NbSe2_2 Detected Using Low Energy β\beta-NMR

A low energy radioactive beam of polarized $^8$Li has been used to observe the vortex lattice near the surface of superconducting NbSe$_2$. The inhomogeneous magnetic field distribution associated with the vortex lattice was measured using depth-resolved $\beta$-detected NMR. Below $T_c$ one observes the characteristic lineshape for a triangular vortex lattice which depends on the magnetic penetration depth and vortex core radius. The size of the vortex core varies strongly with magnetic field. In particular in a low field of 10.8 mT the core radius is much larger than the coherence length. The possible origin of these giant vortices is discussed.Comment: 5 pages, 3 figures. Submitted to Phys. Rev. Let

Vortex lattice disorder in YBCO probed using Beta-NMR

Beta-NMR has been used to study vortex lattice disorder near the surface of the high-Tc superconductor YBCO. The magnetic field distribution from the vortex lattice was detected by implanting a low energy beam of highly polarized 8Li into a thin overlayer of silver on optimally doped, twinned and detwinned YBCO samples. The resonance in Ag broadens significantly below the transition temperature Tc as expected from the emerging field lines of the vortex lattice in YBCO. However, the lineshape is more symmetric and the dependence on the applied magnetic field is much weaker than expected from an ideal vortex lattice, indicating that the vortex density varies across the face of the sample, likely due to pinning at twin boundaries. At low temperatures the broadening from such disorder does not scale with the superfluid density.Comment: 10 pages, 6 figure

Techno-economic modelling of high-value metabolites and secondary products from microalgae cultivated in closed photobioreactors with supplementary lighting

The purpose of this study is to develop an initial computational model to evaluate the techno-economic viability of high-value and secondary resources from microalgae. The isolation of high-value metabolites is the driving product to improve the overall economics. This approach will allow marketing secondary compounds at more competitive rates for applications such as biofuel, biomaterials, food or animal feed supplements. In this assessment, we consider cultivations in flat-panel, airlift and tubular closed photobioreactor [PBR] systems to avoid possible contamination and limit environmental exposures. The facilities are also equipped with supplementary LED lightings and temperature control to improve productivity. Based on the methodology described in this work, we evaluate the techno-economic viability of the suggested systems. A probable productivity range is selected based on the logistic growth with a recovery rate between 60% and 80%. The sensitivity analysis shows that the ratio of high-value metabolites is the most crucial factor determining the economics. Microalgae prices and productivities gain more importance at higher ratios. The sensitivity analyses indicate a low-level impact of productivity and cultivation costs on high priced metabolites

PMSM DTC drive system fed by fault-tolerant inverter connected to a photovoltaic source

International audienc

Algal-algal bioflocculation enhances the recovery efficiency of Picochlorum sp. QUCCCM130 with low auto-settling capacity

Large-scale production of microalgal biomass is still considered non-viable due to the high cost and energy required for harvesting. A fast, cost-effective, and successful harvesting technique has become widely sought after in microalgal biotechnology applications. Algal-algal bioflocculation was adopted for the current study, pH and the ratio between species were selected as two parameters to be optimised. Picochlorum sp. QUCCCM130, Nannochloris sp. QUCCCM31 and Tetraselmis sp. QUCCCM50 presenting a cell size of ∼2 μm, ∼5 μm, and ∼15 μm, respectively, were selected to be subjected to the harvesting optimisation experiments. Results showed that self-settlement capacity increased with cell size and can be indirectly related to a decreased zeta potential of larger cells which enhances the Van der Waals attractive forces. Furthermore, it was noted that pH enhanced the self-settlement capacity of small-sized cells as well that are unable to self-settle. Algal-algal bioflocculation efficiency is dependent on the ratio between species with different sizes, increasing with a higher proportion of larger size microalgal cells. Mixing three microalgae together at pH 10 led to the appearance of large flocs in which the larger cells surrounded the smaller cells. Microscopic observation confirmed that Tetraselmis sp. held the small cells inside the flocs using their flagella. Thus, we can conclude that mixing microalgal cells in a specific ratio and at a specific pH increases the recovery efficiency of small-sized microalgae that can be difficult to harvest, such as Picochlorum sp. QUCCCM130. © 2023 The AuthorsThis publication was made possible by the NPRP grant # [ NPRP8-1087-1-207 ] from the Qatar National Research Fund (a member of Qatar Foundation). Open Access funding provided by the Qatar National Library.Scopu

Assessment of SnO2 nanoparticles' impact on the growth of Picochlorum maculatum algae

To determine the effect of SnO2 nanoparticles on Picochlorum maculatum - isolated from a Qatar marine environment, algal growth media are amended with different nanoparticle concentrations (1, 5, 25, 50, and 100 mg L−1) and the culture was observed for 72 h. Algal growth, morphology, photosynthetic pigments and the potential for producing highly valuable biocompounds (including pigments, lipids, carbohydrates, etc.) are investigated. The data obtained show that the SnO2 nanoparticles have a toxicity effect on the algae growth, with lower doses presenting more negative impacts than higher doses. The results of SEM observations highlight that the slow growth observed at 1-5 mg L−1 is triggered by the attachment of SnO2 nanoparticles to algal cells which caused dramatic damage to the cell morphology, cell shape, and size. However, at high concentrations of SnO2 (50-100 mg L−1), agglomeration of nanoparticles around the cells leads to a reduced effect on cell morphology and appearance. These data are supported by the energy dispersive X-ray spectroscopy (EDX) analysis of the cells after exposure to SnO2. Moreover, the effects of nanoparticles on algae composition are dose specific. Lipids and carbohydrates are stimulated by the decrease in nanoparticle concentrations, while an inhibition in protein production is observed. Besides, the presence of SnO2 at low concentrations stimulates the synthesis of protective molecules such as carotenoids. Hence, exposure to SnO2 nanoparticles can be one of the methods to induce the synthesis of highly valuable products in the local microalgae, which can be used for many applications in different industries