Elucidating the responses of highly time-resolved PM2.5 related elements to extreme emission reductions

Abstract

China's unprecedented lockdown to contain the spread of the novel coronavirus disease (COVID-19) in early 2020, provided a tragic natural experiment to investigate the responses of atmospheric pollution to emission reduction at regional scale. Primarily driven by primary emissions, particulate trace elements is vitally important due to their disproportionally adverse impacts on human health and ecosystem. Here 14 trace elements in PM 2.5 were selected for continuous measurement hourly in urban representative site of Shanghai, for three different phases: pre-control period (1–23 January 2020), control period (24 January-10 February 2020; overlapped with Chinese Lunar New Year holiday) and post control period (11–26 February 2020) the city's lockdown measures. The results show that all meteorological parameters (including temperature, RH, mixing layer height et al.) were generally consistent among different periods. Throughout the study period, the concentrations of most species displayed a “V-shaped” trend, suggesting significant effects by the restriction measures imposed during the lockdown period. While this is not the case for species like K, Cu and Ba, indicating their unusual origins. As a case study, the geographical origins of Cu were explored. Seven major sources, i.e., Vehicle-related emission (including road dust; indicative of Ca, Fe, Ba, Mn, Zn, Cu; accounting for 30.1%), shipping (Ni; 5.0%), coal combustion (As, Pb; 4.2%), Se and Cr industry (24.9%), nonferrous metal smelting (Au, Hg; 7.5%) and fireworks burning (K, Cu, Ba; 28.3%) were successfully pinpointed based on positive matrix factorization (PMF) analysis. Our source apportionment results also highlight fireworks burning was one of the dominant source of trace elements during the Chinese Lunar New Year holiday. It is worth noting that 56% of the total mass vehicular emissions are affiliated with non-exhaust sources (tire wear, brake wear, and road surface abrasion).

Source apportionment of PM2.5 before and after COVID-19 lockdown in an urban-industrial area of the Lisbon metropolitan area, Portugal

“…These results are in line with other works that have shown significant reductions in PM 2.5 primary components concentrations (e.g. K, Fe, Zn, Ba, Mn, Pb, Cu, As, Ni, Se and Cr, in Cheng et al (2022) ; Cr, Fe, Na + , Cl − , Pb, Ca, Cr, Cu, Fe, Zn and EC, in Li et al (2021) ; Zn, Pb, Mn, As, Cu, Ni, V, Cr, Cd and Co, in Wang et al (2021b) ; Cd, Se, As, Sr, Ba, Cu, Mn, Pb, K, Zn, Ca, Al, and Mg, in Nguyen et al (2022) ), attributed as an effect of the measures imposed by the COVID-19 lockdown. Soil elements Al and Si, did not vary significantly, since being of natural origin, were less affected by the reduction of anthropogenic activities.…”

“…Globally, these results are in line with other works, where PMF source apportionment generally revealed decreased contributions of vehicle emissions ( Cui et al, 2020 ; Cheng et al, 2022 ; Wang et al, 2021a ) and in some cases, also increased contributions of secondary inorganic aerosol ( Chang et al, 2022 ; Hong et al, 2021 ; Massimi et al, 2022 ).…”

“…There are some studies that report the comparison of PM 2.5 chemical composition and source contributions in the pre- and post-confinement periods ( Hong et al (2021) ; Cheng et al (2022) ; Cui et al (2020) ; Fatima et al (2022) ; Li et al (2021) ; Zheng et al (2020) ; Nguyen et al (2022) ; Wang et al (2021a) and Chang et al (2020) ), but only few are relative to European urban-industrial areas ( Massimi et al (2022) ; Hicks et al (2021) ) and none to Portugal, to the best of our knowledge.…”

The Atmospheric Environment Effects of the COVID-19 Pandemic: A Metrological Study

“…In 2020, the meteorological data of Shanghai during the lockdown period and before and after the lockdown were consistent. The comparison of 14 trace elements in PM 2.5 found that the concentration of trace elements in most fine particles showed a “V” shape trend, indicating that the lockdown measures had a significant impact [ 34 ]. Comparing the air quality index (AQI) results before and after the impact of COVID-19 across India shows that most pollutant concentrations (PM 10 , PM 2.5 , CO, SO 2 , NO x ) show different patterns of gradual to rapid decreases [ 35 , 36 ].…”

Life-Course Health Risk Assessment of PM2.5 Elements in China: Exposure Disparities by Species, Source, Age, Gender, and Location

“…PM 2.5 -bound elements have long been considered trace components (“trace elements”) and are mainly used to infer particulate sources. − Recently, in addition to toxicological studies, there has been increasing interest in linking human health risks with PM 2.5 -bound element measurements to inform mitigation policies. − This is particularly true in China, where haze pollution featuring high PM 2.5 loadings continued to be a severe environmental and health concern in North China Plain, the Yangtze River Delta region, and the Pearl River Delta region . For example, Huang et al characterized the concentration and fractionation of 14 elements in Beijing and concluded that traffic-related emission dominated the carcinogenic risk (CR) and noncarcinogenic risk (NCR) by PM 2.5 -bound elements during low pollution days, while coal combustion becomes equally or even more important during moderate and severe pollution days.…”