Atmospheric Science Cluster
http://hdl.handle.net/10576/3405
2024-03-28T18:16:48ZIn-site and ex-site date palm exposure to heavy metals involved infra-individual biomarkers upregulation
http://hdl.handle.net/10576/48083
In-site and ex-site date palm exposure to heavy metals involved infra-individual biomarkers upregulation
Chaâbene, Zayneb; Rorat, Agnieszka; Kriaa, Walid; Rekik, Imen; Mejdoub, Hafedh; Vandenbulcke, Franck; Elleuch, Amine
As a tree of considerable importance in arid regions—date palm, Phoenix dactylifera L. survival in contaminated areas of Sfax city has drawn our attention. Leaf samples of the plants grown in the study area showed high levels of cadmium (Cd), copper (Cu), and chromium (Cr). On the basis of this finding, the cellular mechanisms that explain these metal accumulations were investigated in controlled conditions. After four months of exposure to Cd, Cr, or Cu, high bioconcentra-tion and translocation factor (TF>1) have been shown for date palm plantlets exposed to Cd and low TF values were obtained for plantlets treated with Cr and Cu. Moreover, accumulation of oxidants and antioxidant enzyme activities occurred in exposed roots to Cu and Cd. Secondary metabolites, such as polyphenols and flavonoids, were enhanced in plants exposed at low metal concentrations and declined thereafter. Accumulation of flavonoids in cells may be correlated with the expression of the gene encoding Pdmate5, responsible for the transport of secondary metabolites, especially flavonoids. Other transporter genes responded positively to metal incorporation, especially Pdhma2, but also Pdabcc and Pdnramp6. The latter would be a new candidate gene sensitive to metallic stress in plants. Expressions of gene coding metal chelators were also investigated. Pdpcs1 and Pdmt3 exhibited a strong induction in plants exposed to Cr. These modifications of the expression of some biochemical and molecular based-markers in date palm helped to better understand the ability of the plant to tolerate metals. They could be useful in assessing heavy metal contaminations in polluted soils and may improve accumulation capacity of other plants.
2021-01-12T00:00:00ZLong-term assessment of onshore and offshore wind energy potentials of Qatar
http://hdl.handle.net/10576/47340
Long-term assessment of onshore and offshore wind energy potentials of Qatar
Aboobacker, Valliyil Mohammed; Shanas, Puthuveetil Razak; Veerasingam, Subramanian; Al-Ansari, Ebrahim M.A.S.; Sadooni, Fadhil N.; Vethamony, Ponnumony
Exploitation of conventional energy resources has caused a deliberate increase in the emitted carbon in the atmosphere, which catalyzes global warming trends. This is a matter of concern, especially in Qatar, where fossil fuels (oil and gas) are largely relied upon for power production. The dependency on such resources could be gradually reduced by utilizing clean and renewable energy. Resource characterization is an important step to evaluate the potentiality of available renewable energy sources. Wind energy is one among them, which has not been assessed reliably so far in Qatar. We analyzed the wind energy potential along the onshore and offshore areas of Qatar using 40 years (1979–2018) of hourly wind data extracted from the ECMWF Reanalysis v5 (ERA5) database. Monthly, seasonal, annual, and decadal mean wind power densities have been derived. Reliability tests have been carried out at select onshore and offshore locations. Trends and inter-annual variability have been assessed. The study reveals that the available wind resources are generally moderate but consistent with no intense trends during the 40 year period. An inter-annual variability in wind power has been identified, which has secured links with the El Niño–Southern Oscillation (ENSO).
2021-02-02T00:00:00ZHuman health risks associated with trace metals in dust of residential arid areas
http://hdl.handle.net/10576/43525
Human health risks associated with trace metals in dust of residential arid areas
Basem, Shomar; Rashkeev, Sergey N.
Composite dust samples were collected on a monthly basis over a full year from Doha, Qatar. Inductively Coupled Plasma Mass Spectrometry (ICPMS) was used for the determination of total concentrations of Na, K, Mg, Ca, Li, Be, B, V, Cr, Fe, Mn, Co, Ni, Cu, Zn, As, Se, Sr, Cd, Ba, Al, Pb, Ag, TI, U, Sb, Si, Sn, Mo and Bi. A combined approach, merging conventional sampling and analysis with subsequent numerical calculations of the risk of exposure to toxic elements, was employed. For assessment of the health risks associated with the regular exposure to dust, the exposure routes related to the dermal contact and inhalation were considered. Our results indicate that the total non-carcinogenic health risk through exposure to different elements (Hazardous Quotients, HQ's) that are contained in the dust are quite low (well below unity) for both dermal contact and inhalation routes in all months of the year, i.e., there is no risk to the human health. There is no clear explanation for the seasonal variation of metals in the dust in the Qatar area. Several elements in the dust collected in the summertime have higher concentration than in the wintertime. This could be due to the weather conditions and natural depositions. However, the content of several elements (Pb, Zn, Cu, Sn and Li) showed elevation in the wintertime. For dermal exposure, the dominant contribution to the Hazardous Index (HI) comes from thallium (Tl) while for inhalation exposure several comparable contributions are related to Mn, Sb, Si, Ni, and Co. Long-term monitoring strategies are still needed for detailed research on dust pollutants and potential risks.
2023-04-07T00:00:00ZImpact of alternate Mn doping in ternary nanocomposites on their structural, optical and antimicrobial properties: Comparative analysis of photocatalytic degradation and antibacterial activity
http://hdl.handle.net/10576/42813
Impact of alternate Mn doping in ternary nanocomposites on their structural, optical and antimicrobial properties: Comparative analysis of photocatalytic degradation and antibacterial activity
Tahir, Noor; Zahid, Muhammad; Jillani, Asim; Tahir, Suman; Yaseen, Muhammad; Abbas, Qamar; Abdul Shakoor, Rana; Hussain, Syed Zajif; Shahid, Imran
The present study was done to investigate and compare the photocatalytic and antibacterial activity of two in situ Manganese doped ternary nanocomposites. The dual ternary hybrid systems comprised Mn-doped Ag2WO4 coupled with MoS2-GO and Mn-doped MoS2 coupled with Ag2WO4-GO. Both hierarchical alternate Mn-doped ternary heterojunctions formed efficient plasmonic catalysts for wastewater treatment. The novel nanocomposites were well-characterized using XRD, FTIR, SEM-EDS, HR-TEM, XPS, UV-VIS DRS, and PL techniques confirming the successful insertion of Mn+2 ions in respective host substrates. The bandgap of the ternary nanocomposites evaluated by the tauc plot showed them visible light-active nanocomposites. The photocatalytic ability of both Mn-doped coupled nanocomposites was investigated against the dye methylene blue. Both ternary nanocomposites showed excellent sunlight harvesting ability for dye degradation in 60 min. The maximum catalytic efficiency of both photocatalysts was obtained at a solution pH value of 8, photocatalyst dose and oxidant dose of 30 mg/100 mL and 1 mM for Mn-Ag2WO4/MoS2-GO, 50 mg/100 mL, 3 mM for Mn-MoS2/Ag2WO4-GO keeping IDC of 10 ppm for all photocatalysts. The nanocomposites showed excellent photocatalytic stability after five successive cycles. The response surface methodology was used as a statistical tool for the evaluation of the photocatalytic response of several interacting parameters for dye degradation by ternary composites. The antibacterial activity was determined by the inactivation of gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria by support-based doped ternary hybrids. 2023 Elsevier Ltd
2023-01-01T00:00:00Z