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Under the harsh environmental conditions characterized by intense ultraviolet radiation and elevated ozone (O3) background, the temporal dynamics of atmospheric O3 concentrations and their associated environmental ramifications in the densely populated and emission-concentrated urban regions of the Tibetan Plateau have garnered considerable scientific interest. This comprehensive study meticulously compiles O3 concentration data spanning 2015 to 2023 from 7 cities of Xizang, conducting rigorous trend analyses and employing a robust suite of 13 risk assessment indicators to gauge the implications for human health and ecological vegetation. It shows that O3 concentrations of these cities demonstrate significant geographical variations, with the central city of Lhasa recording the highest O3 mass concentration, while those in the southern cities of Shannan and Rikaze are relatively lower. O3 concentrations of Nagqu, located in the north, are comparable to those of Lhasa and are significantly higher than those of Ali in the west, as well as those of Linzhi and Changdu in the east Plateau. O3 concentrations of Changdu and Linzhi peak in June and March-April, respectively, while the other cities reach their peaks in May. Since 2015, interannual variations in O3 concentrations of Ali, Nagqu, Lhasa, and Linzhi do not show statistically significant trends. In contrast, Shannan, Rikaze, and Changdu experience significant increases in concentration. Specifically, AMDA8_max and AMDA8_4th in Rikaze and Changdu increase significantly, whereas the other cities show decreasing trends. Similarly, both NDGT90 and NDGT70 exhibit comparable trends. SOMO35 indicator, which indicates human health risks, and AOT40 and W126 indicators, which are closely related to ecological vegetation and crop growth, show a high degree of consistency in their trends relative to diurnal O3 concentration changes. In Lhasa, values of these indicators exceed safety thresholds, particularly during spring and summer, highlighting the combined effect of high background O3 concentrations in the Plateau and intensified O3 photochemical formation due to anthropogenic emissions, posing potential threats to human health and ecosystems. Although the current O3-related risk indicators of Rikaze and Changdu have not yet reached critical levels, their significant upward trends should not be overlooked. With the continuous rise in anthropogenic pollutant emissions in the region, adverse effects of O3 photochemical formation are anticipated to intensify. Therefore, there is an urgent need to enhance monitoring and assessment in these cities and to implement effective measures to mitigate or control O3 pollution, thereby safeguarding regional environmental security and promoting sustainable development.

This note gives a classification for the spectral measures of CMV matrices, which are special unitary five-diagonal matrices related to orthogonal polynomials on the unit circle, with respect to packing measures. [ABSTRACT FROM AUTHOR]

Oxygenated volatile organic compounds (OVOCs) are reactive species and the primary precursors of free radicals; thus, OVOCs play important roles in tropospheric chemistry. @Tibet field campaigns 2021 discovered surprisingly high levels and activity contributions of OVOCs at Lulang, a site with high vegetation cover and strong solar ultraviolet radiation on the southeast of the Tibetan Plateau (TP). The 13 OVOCs detected accounted for 49 % of the total VOCs (TVOCs; average level of 11.7 ± 4.4 ppb), and the levels of these OVOCs exhibited typical diurnal variation, with high values in the daytime and a peak at approximately 12:00. OVOCs contributed 65 % and 63 % to VOC- k OH and the ozone formation potential, respectively, and thus had a strong influence on atmospheric chemical processes. Two independent methods were used to determine the contributions of various sources and revealed consistent conclusions regarding the importance of biological sources there. The source apportionment results obtained through positive matrix factorization indicated that sunlight-impacted and direct plant emission sources both related to plant sources contributed 47 % of the TVOCs and 65 % of the OVOCs. OVOC source fitting through the photochemical age parameterization method also indicated that biogenic sources made the largest contribution (67 %) to OVOCs and revealed a clear peak at noon. In addition, biomass burning sources were found to be closely related to the VOC background because biomass burning is highly prevalent across the whole TP; these sources made the second greatest contribution (33 %) to the TVOCs and contributed more than 23 % of OVOCs. [ABSTRACT FROM AUTHOR]

Hypoxia and adverse health outcomes might be affected by O 3 pollution in the highland city of Lhasa. NO x emissions can amplify the role of volatile organic compounds (VOCs) in the secondary production of O 3 under the conditions of high ultraviolet (UV) radiation levels and unfavourable dispersion patterns in the Lhasa River valley. Here, online C 2 –C 11 VOC measurements, accompanied by other parameters concerning the O 3 chemical budget, were first obtained and employed to identify the key VOC species and key sources of VOCs in terms of the loss rate against OH radicals (LOH), ozone formation potential (OFP), secondary organic aerosol potential (SOAP), and toxicity. Oxygenated VOCs (OVOCs) not only were the most abundant VOCs but also dominated LOH , OFP, and toxicity. Isoprene and anthropogenic VOCs were further identified as precursors of these OVOCs. Aromatics accounted for 5 % of the total VOCs (TVOCs) but contributed 88 % to the SOAP and 10 % to the toxicity. As the primary oxidative intermediates of aromatics were not well characterized by our measurements, the environmental impact of aromatics could be underestimated by our data. Source appointment and ternary analysis of benzene, toluene, and ethylbenzene confirmed the combined contribution of traffic emissions, solvent usage, and biomass burning. This suggests that O 3 precursors are mainly from sources associated with residents' lives, except for solvent usage emissions which contribute to aromatics. Preliminary comparisons between source spectrums of transport sector emissions with positive matrix factorization (PMF)-decomposed ones and our measured ones suggest that vehicle emission patterns of VOCs at high altitude generally follow the ground-level impression. More quantitative data are required to further confirm this point though. Emission reduction strategy analysis for O 3 pollution control highlighted multiple benefits of the simultaneous reduction in NO x originating from diesel vehicle emissions, biomass burning, and background sources (possibly dominated by incense burning). The notable biogenic emission contribution to the OFP was also first confirmed in our study, and this highlights the side effects of the government's pursuit of a greener city. [ABSTRACT FROM AUTHOR]

Hypoxia and adverse health outcomes might be complexed with O3 pollution in the highland city of Lhasa. NOx emissions can amplify the role of volatile organic compounds (VOCs) in the secondary production of O3 under the conditions of high ultraviolet (UV) radiation levels and unfavourable dispersion patterns in the Lhasa River valley. Here, online C2-C11 VOC measurements, accompanied by other parameters concerning the O3 chemical budget, were first obtained and employed to identify the key VOC species and key sources of VOCs in terms of the loss rate against OH radicals (LOH), ozone formation potential (OFP), secondary organic aerosol potential (SOAP) and toxicity. Oxygenated VOCs (OVOCs) were not only the most abundant VOCs but also dominated LOH, OFP and toxicity. Isoprene and anthropogenic VOCs were further identified as precursors of these OVOCs. Aromatics accounted for 5 % of the total VOCs (TVOCs) but contributed 88 % to the SOAP and 10 % to the toxicity. As the primary oxidative intermediates of aromatics were not well characterized by our measurements, the environmental impact of aromatics could be underestimated by our data. Source appointment and ternary analysis of benzene, toluene, and ethylbenzene confirmed the combined contribution of traffic emissions, solvent usage and biomass burning. This suggests that O3 precursors are mainly from residents' life associated sources, except for solvent usage emissions which contribute to aromatic. Preliminary comparisons between source spectrums of transport sector emissions with PMF decomposed ones and our measured ones suggest that vehicle emission patterns of VOCs at high altitude generally follows the ground-level impression. More quantitative data is required to further confirm this point though. Emission reduction strategy analysis for O3 pollution control highlighted multiple benefits of the simultaneous reduction in NOx originating from diesel vehicle emissions and biomass burning and background sources (possibly dominated by incense burning). The notable biogenic emission contribution to the OFP was also first confirmed in our study, and this highlights the side effects of the government's pursuit of a greener city. [ABSTRACT FROM AUTHOR]

The charcoal trap adsorption device was designed and used to adsorb the volatile organic compounds (VOCs) emitted from Ginkgo leaves and Lima beans. The adsorbed VOCs were determined using gas chromatography-mass spectrometry (GC-MS). Compared to solid phase microextraction (SPME), the self-made charcoal trap adsorption device was more advantageous to the enrichment of VOCs from Ginkgo leaves. Additionally, the quantitative analysis of the collected VOCs released from Lima beans was carried out through the addition of internal standard, and the results of the two parallel experiments showed good repeatability. Because the eluent of the charcoal trap can be stored and used in the quantitative analysis as well as parallel experiments, the self-made charcoal trap adsorption device coupled with GC-MS is suitable for laboratory studies of plant volatile organic compounds.