Characteristics of environmentally persistent free radicals in PM2.5: Concentrations, species and sources in Xi'an, Northwestern China

Chen, Qingcai; Sun, Haoyao; Mu, Zhen; Wang, Yuqin; Li, Yanguang; Zhang, Lixin; Wang, Mamin; Zhang, Zimeng

doi:10.1016/j.envpol.2019.01.015

Cited by 70 publications

(77 citation statements)

References 42 publications

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“…7, the averaged decayable amount of EPFRs in PM 2.5 under such conditions would be amounted to 21.7%. This value is quite similar to the averaged values during fall (20-25%) and winter (10-15%) reported by Chen et al [34].…”

Section: Lifetime and Decay Of Epfrssupporting

confidence: 92%

“…Thus far, we have reported data of EPFRs in airborne PM in six countries, i.e., China, Germany, Greece, India, Saudi Arabia and the USA. As listed in Table 1, there are various forms of sampling media for airborne PM, including a glass fiber filter (GFF) [21,31], quartz fiber filter (QFF) [32][33][34][35], Teflon membrane filter (TMF) [24,36,37], polytetrafluoroethylene (PTFE) [35,38,39], polycarbonate filter (PCF) [40], and even a leaf [41].…”

Section: Samplingmentioning

confidence: 99%

“…It is apparent that the majority (16 out of 23) of the studies show an average g-value between 2.003 and 2.004, which were mostly attributed to semiquinone radicals (Table 4). The three datasets with a g-value greater than 2.004 were all from the research conducted in Memphis [41], while those with the mean g-value less than 2.003 were from Jinan (2.0029) [33] and Xi'an during the fall season (2.0029) [34]; the latter were mostly assigned as carbon-centered radical or carbon-centered radical with adjacent heteroatoms. Overall, an averaged g-value of 2.0035 ± 0.0056 was obtained for all 23 investigations.…”

Section: Types Of Epfrsmentioning

confidence: 99%

“…In comparison, the lifetime of EPFRs in airborne PM is generally much longer, on average, ranging from 6.2 [39] to 81 days [46] for fast decay and from 142 [39] to 694 days [46] for the slow decay (Table 5). A total of five decay processes were reported in the literature for the EPFRs in PM 2.5 , i.e., single slow decay (SD) [32,39], single no decay (ND) [34,39], fast decay followed by slow decay (FD-SD) [34,39,46], fast decay followed by no decay (FD-ND) [34,39,46] and slow decay followed by no decay (SD-ND) [32,34]. Among all the investigations, only one study observed the fast growth (FG) of EPFRs in an extractable WISM sample proceeding the SD and FD-SD/ND [46].…”

Section: Lifetime and Decay Of Epfrsmentioning

confidence: 99%

“…The remaining process (4.5% of the cohort) is the SD-ND, where the SD mode has a 1/e lifetime of 362 ± 58.7 days. As listed in Table 5, the decayable EPFRs in PM 2.5 only account or 20-25% and 10-15% of the total EPFRs present in the PM 2.5 samples collected in fall and winter in Xi'an in 2017, respectively [34], indicating that the majority of the EPFRs in PM 2.5 are not degradable.…”

Section: Lifetime and Decay Of Epfrsmentioning

confidence: 99%

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Environmentally persistent free radicals in PM2.5: a review

Tang

et al. 2019

Waste Dispos. Sustain. Energy

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Environmentally persistent free radicals (EPFRs) are a new class of pollutants that are long-lived in fine particles (PM 2.5), i.e., their 1/e lifetime ranges from days to months (or even infinite). They are capable of producing harmful reactive oxygen species such as hydroxyl radicals. The redox cycling of EPFRs is considered as an important pathway for PM 2.5 to induce oxidative stress inside the humans, causing adverse health effects such as respiratory and cardiovascular diseases. Consequently, research regarding their toxicity, formation and environmental occurrences in PM 2.5 has attracted increasing attentions globally during the past two decades. However, literature data in this field remain quite limited and discrete. Hence, an extensive review is urgently needed to summarize the current understanding of this topic. In this work, we systematically reviewed the analytical methods and environmental occurrences, e.g., types, concentrations, and decay behaviors, as well as possible sources of EPFRs in PM 2.5. The types of pretreatment methods, g-values of common EPFRs and categories of decay processes were discussed in detail. Moreover, great efforts were made to revisit the original data of the published works of EPFRs in airborne particulate matter and provided additional useful information for comparison where possible, e.g., their mean and standard deviation of g-values, line widths (∆H p-p), and concentrations. Finally, possible research opportunities were highlighted to further advance our knowledge of this emerging issue.

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Section: Lifetime and Decay Of Epfrssupporting

confidence: 92%