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The Xiahe Ms5.7 earthquake occurred in Xiahe county, Gannan prefecture, China (35.10°N, 102.69°E) on October 28, 2019, with a source depth of 10 km. This study investigates the spatial and temporal evolution characteristics of cross-fault soil gas concentrations prior to the Xiahe Ms5.7 earthquake by analyzing Rn, Hg, H2, and CO 2 data collected from 11 profiles across the northern margin of the West Qinling fault zone from 2016 to 2019. The spatial distribution of these gases showed varying trends, with Rn concentration intensity decreasing from the Wushan segment to the east and west sections, while Hg, H 2 , and CO 2 all broke the trend in the West Qinling fault zone's northern margin. The soil gas concentration intensity demonstrated a significant response to the Xiahe Ms5.7 earthquake, particularly in the west Ganjia sections. By integrating the seismogenic model and numerical simulation results, we explored the physical mechanism underlying these abnormal trends. Our findings suggest that the continuous decline characteristic of fault gas could be a valuable indicator of fracture tectonic activity, while an upward trend after continuous decline may signal a medium and short-term seismogenic event in the source area. These results provide a foundation for improved tracking of earthquake location and timing in a fault zone through cross-fault soil gas methods, highlighting the importance of enhancing deep fluid flow monitoring and seismogenic model research in fault zones., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people ororganizations that can in appropriately influence our work, there is no professional or otherpersonal interest of any nature or kind in any product, service and/or company that could beconstrued as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2023. Published by Elsevier Ltd.)

(1) Background: Recognising the full spatial and temporal distribution of PM 2.5 is important in order to understand the formation, evolution and impact of pollutants. The high temporal resolution satellite, Himawari-8, providing an hourly AOD dataset, has been used to predict real-time hourly PM 2.5 concentrations in China in previous studies. However, the low observation frequency of the AOD due to long-term cloud/snow cover or high surface reflectance may produce high uncertainty in characterizing diurnal variation in PM 2.5 . (2) Methods: We fill the missing Himawari-8 AOD with MERRA-2 AOD, and drive the random forest model with the gap-filled AOD (AOD H+M ) and Himawari-8 AOD (AOD H ) to estimate hourly PM 2.5 concentrations, respectively. Then we compare AOD H+M -derived PM 2.5 with AOD H -derived PM 2.5 in detail. (3) Results: Overall, the non-random missing information of the Himawari-8 AOD will bring large biases to the diurnal variations in regions with both a high polluted level and a low polluted level. (4) Conclusions: Filling the gap with the MERRA-2 AOD can provide reliable, full spatial and temporal PM 2.5 predictions, and greatly reduce errors in PM 2.5 estimation. This is very useful for dynamic monitoring of the evolution of PM 2.5 in China.

Risk assessment and minimisation of environmental hazards are critical issues to consider in the geotechnical engineering projects. A case of highway pavement seepage induced by groundwater, at a locality along the section of Hua-Qing Highway of Guangdong Province, China, is presented for environmental hazard analysis and effective remediation. The environmental hazard analyses were based on in situ hydrogeologic investigation, rock-soil testing and integrated environmental understanding. The analyses indicate that the highway seepage was caused by elevation of groundwater hydraulic pressure in low permeable strata near the highway pavement, which was controlled by landform, hydrology, weather and road structure. The risk source of groundwater 'flooding' was the groundwater and surface water in the ring-like valley around Fenshui Village. A blind-ditch system for effective remediation of the pavement seepage hazard was proposed and successfully implemented by declining groundwater table near the highway based on the comprehensive assessment of various conditions. This geotechnical accident shows that the role of groundwater is an essential factor to consider in the geotechnical and environmental engineering studies and multidisciplinary effort for risk assessment of environmental hazards is important under current global climate change condition.