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• Systemic measured the effectiveness of LDAR surveys addressed fugitive VOCs emissions. • Reported an obvious reduction of the fugitive VOCs leaks after LDAR implementation. • Quantified and characterized the process-based fugitive VOC emissions from a local petroleum refinery. • Emphasized the contribution of the LDAR technology in economic and environmental benefits. Fugitive volatile organic compound (VOC) emissions from the petroleum-refining industry constitute a complex issue in China. This problem has a wide range of implications that require comprehensive measures, including a series of critical policing and legal injunctions in response to regional atmospheric pollution and the resulting safety hazards. In particular, process-based leak detection and repair (LDAR) surveys commonly used in developed countries should be vigorously promoted for fugitive VOC emission reduction. In this study, a campaign was conducted to measure the effectiveness of LDAR surveys by quantifying fugitive VOC emissions caused by equipment leaks in a local petroleum refinery in the Pearl River Delta (PRD) region of China. The leakage points detected in the initial survey accounted for 0.63 % of all the components within the refinery, among which open-ended pipes and valve packing had the highest ratio. After the procedure, the leakage rate was reduced to 0.23 %, suggesting a satisfactory repair performance. The process-based fugitive emission characteristics of each refining unit, storage tank, and loading area were investigated, and the corresponding composite profiles were estimated using the correlation equation method and data from the LDAR survey. Results demonstrated that the total emission of the refinery was 12,595.83 kg/a, with dominant VOC species of alkanes being emitted in nearly all units. Finally, the secondary organic aerosol formation potential (SOAP) and ozone formation potential (OFP) were estimated. All the above results were process-oriented and demonstrated that establishing a local LDAR system that considers the differences in VOC emissions from various manufacturing facilities should be the key strategy for future VOC emission reduction from the entire petroleum refining industry in China. [ABSTRACT FROM AUTHOR]

Over the past decade, secondary pollution characterized by active photochemistry has sharply increased and become the major contributor to air pollution in China, despite the great reduction of primary emissions. Peroxyacetyl nitrate (PAN) is an excellent indicator of photochemical pollution. Observation of PAN in high-elevation atmosphere offers a rare opportunity to understand the degree of photochemical activity in a wide region. In this study, we conducted a field campaign at a high-altitude (1690 m a.s.l.) national background site on the border of South and Central China during photochemically polluted seasons (Sep–Nov 2018). PAN showed significantly higher concentrations than other high-elevation sites worldwide, with hourly mean and maximum values of 0.52 ± 0.45 ppbv and 2.33 ppbv, respectively. Episodes with much higher PAN levels (1.03 ± 0.40 ppbv) than backgrounds (0.24 ± 0.13 ppbv) were captured. Nighttime peaks suggested mixed impacts of regional transport and VOCs oxidation by nitrate radical and O 3. High background O 3 (44.30 ± 0.44 ppbv) was derived from the significant positive correlation of O 3 with PAN. Contributions of downward transported PAN from upper troposphere were found to be non-negligible. Further analyses revealed that regional transport from Central China contributed substantially to the high levels of PAN, with only a minor contribution coming from the south where the Pearl River Delta (PRD) metropolitan region is located. Our results might indicate the great achievement in air quality improvement in the PRD, and also suggest that a strategic shift of control focus from metropolitan to developing areas is urgently needed for mitigating the severe photochemical pollution in China. [Display omitted] • First observations of PAN in the high-elevation background atmosphere of South-Central China. • Higher PAN concentrations than those at other high-elevation sites worldwide were observed. • Relatively high background O 3 was obtained from linear regression of O 3 and PAN. • Air masses coming from Central China significantly enhance the PAN levels. • Strategic shift of control focus from metropolitan to developing areas in China is suggested. [ABSTRACT FROM AUTHOR]