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Based on the analysis of air quality data in Yunnan Province from 2015 to 2020, combined with spatial interpolation analysis and geographic detector factor analysis, the spatial–temporal evolution characteristics of air quality in Yunnan Province have been studied, and the main driving factors, the mechanisms, and the impact of regional COVID-19 control measures affecting air quality have been discussed. The results show that the air quality in Yunnan Province was generally good (superior rate > 98%) from 2015 to 2020, that the Air Quality Index (AQI) value is better in the wet season than in the dry season, and that the concentration of major pollutants shows a decreasing trend. AQI values are spatially high in the east and low in the west. The relative humidity, precipitation, population density, building construction area, and civil vehicles have a greater degree of explanation for the spatial differentiation of AQI, whereas the synergistic influence (maximum value 0.92) of socio-economic factors and meteorological factors is significantly greater than that of a single factor (maximum value 0.80) by the geographic detector model. The control measures for COVID-19 in 2020 reduced the concentration of major pollutants in the atmosphere to a certain extent. Controlling regional air pollution in urban agglomerations in low-latitude plateau areas can improve their air quality by reducing human activities. However, the control of O3 concentration is more complex, and more restrictive factors need to be considered. The results will provide a scientific basis for the prevention and control of air pollution in plateau cities. [ABSTRACT FROM AUTHOR]

• The LRCE model can quantitatively applied to correct the element results of lake sediment by XRF. • The human activity and soil erosion have been reconstructed by geochemical indicators. • The major influence factors of soil erosion in ISM region have certain differences at different periods. Climate and human activities have changed land use patterns and the surrounding environment since the mid-late Holocene. X-ray Fluorescence (XRF) can provide a fast, non-destructive and high-resolution method for elemental analysis in these studies. However, the semi-quantitative results of XRF element scanning are difficult to compare with other regional environmental proxies in different regions. Here, we investigated the geochemical and other environmental proxies of Fuxian Lake sediments using the elemental log-ratio calibration equation (LRCE) and wavelet analysis, reconstructing a comprehensive historical account of soil erosion and human activity in the lake catchment area over the past 5000 years. The results revealed that elemental log-ratios, such as ln(Rb/Sr), ln(Ti/Sr), ln(Zr/Sr), and ln(Fe/Mn), reliably indicate soil erosion in the Fuxian Lake catchment. Moreover, the results of wavelet transform coherence analysis (WTC) indicate that there is a 1000-year periodic signal in the geochemical records of lake sediments since 5000 cal. a BP. This suggests that soil erosion processes in the lake catchment on a millennial scale were predominantly controlled by climatic changes in the mid-Holocene, and a distinct 20 ∼ 50-year periodic signal emerged after 2200 cal. a BP., indicating enhanced erosion within the lake catchment. It has been confirmed by the records of intensified human activity and the rapid expansion of agricultural cultivation after 2200 cal. a BP., and supported by regional archaeological data. Meanwhile, human activities have had a lasting impact on the sedimentary characteristics and land-use patterns of the lake catchment over the past ∼ 2000 years. This research will enhance our understanding of how land-use and soil erosion within lake catchments respond to human activities, thus affecting long-term environmental transformations in the southeastern Tibetan Plateau margin. [ABSTRACT FROM AUTHOR]