Detecting nitrogen oxide emissions in Qatar and quantifying emission factors of gas-fired power plants : a 4-year study

Nitrogen oxides (NOx = NO + NO2), produced in urban areas and industrial facilities (particularly in fossil-fuel-fired power plants), are major sources of air pollutants, with implications for human health, leading local and national authorities to estimate their emissions using inventories. In Qatar, these inventories are not regularly updated, while the country is experiencing fast economic growth. Here, we use spaceborne retrievals of nitrogen dioxide (NO2) columns at high spatial resolution from the TROPOspheric Monitoring Instrument (TROPOMI) to estimate NOx emissions in Qatar from 2019 to 2022 with a flux-divergence scheme, according to which emissions are calculated as the sum of a transport term and a sink term representing the three-body reaction comprising NO2 and hydroxyl radical (OH). Our results highlight emissions from gas power plants in the northeast of the country and from the urban area of the capital, Doha. The emissions from cement plants in the west and different industrial facilities in the southeast are underestimated due to frequent low-quality measurements of NO2 columns in these areas. Our top-down model estimates a weekly cycle, with lower emissions on Fridays compared to the rest of the week, which is consistent with social norms in the country, and an annual cycle, with mean emissions of 9.56 kt per month for the 4-year period. These monthly emissions differ from the Copernicus Atmospheric Monitoring Service global anthropogenic emissions (CAMS-GLOB-ANT_v5.3) and the Emissions Database for Global Atmospheric Research (EDGARv6.1) global inventories, for which the annual cycle is less marked and the average emissions are respectively 1.67 and 1.68 times higher. Our emission estimates are correlated with local electricity generation and allow us to infer a mean NOx emission factor of 0.557 t NOx GWh−1 for the three gas power plants in the Ras Laffan area

Stability after dilution of an oral L-glutamine preparation

Objective: Glutamine is a conditionally essential amino acid. Attention has been focusing recently on the potential non-nutritional effects of Glutamine including gut protection, enhancement of cell-mediated immunity, cell-volume regulation, synthesis of heat-shock proteins, and incretinsecretagogue action, which may play a crucial role in the regulation of glucose metabolism. However, the relative instability of Glutamine in water may reduce the effectiveness of oral preparations of Glutamine and/or decrease patient compliance. Design: The aim of this study was to investigate the stability of an oral L-Glutamine preparation. Materials and methods: An oral Glutamine powder preparation (Adamin-G, SHS International Ltd, UK, kindly provided by Nutricia Italy) was tested. One sachet (containing 5 g of L-Glutamine, as indicated by the producer) was diluted in 200 mL of water to obtain a solution with a nominal concentration of 170 μmol/mL. Samples were obtained at 0, 2, 6, 12, and 24 hours after dilution and analyzed by highperformance liquid chromatography. Results: The mean measured concentrations of Glutamine (g/200 mL) in the samples were as follows: 0h: 5.095±0.17; 2h: 5.098±0.06; 6h: 5.090±0.09; 12h: 5.103±0.07; 24h: 5.007±0.01 (p=ns at ANOVA). Conclusion: These results show that a commercially available oral L-Glutamine preparation is stable for at least 24 hours after dilution in water. This may have critical clinical relevance in patients unable to comply with fast oral intake of supplements, allowing day-long administration and improving patient compliance. Oral L-Glutamine supplements may prove beneficial in a number of clinical conditions and thus represent an emerging tool for metabolic support. © 2010 SINPE-GASAPE