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The spatio-temporal distribution of geological hazards, including collapses, landslides, and debris flows, in Shaanxi province, China was studied based on data from 1951 to 2018. The potential impact factors, including the geomorphologic types, rivers, roads, rainfall, and earthquakes, were analyzed using Random Forests. The results indicated that most hazards occurred in summer (i.e., July–September) and were triggered by rainstorms. The freeze–thaw effect had a considerable contribution to hazards in the north. Spatially, most hazards in the north occurred in valley terraces of the Loess Plateau, while medium-relief terrane (relief ranged from 500 to 1000 m) in the southern Qinling Mountains were hazard-prone areas. The collapses and landslides were mainly affected by human factors in Northern Shaanxi, whereas in Southern Shaanxi geomorphology was the primary factor. Permeability was a dominant factor for debris flows. In addition, the 2008 Wenchuan earthquake had a remarkable influence on the spatial distribution of hazards. In contrast, for the situation in the Sichuan province, which was close to the earthquake epicenter, the Wenchuan earthquake triggered many collapse and landslide events in the southwest regions of Shaanxi province only on 12 May 2008. The thresholds for the three hazard types in the north and south regions were almost the same despite their distinctly different geologic characteristics. Through a sensitivity analysis, we found an appropriate dry period of 12 h for the area. [ABSTRACT FROM AUTHOR]

China continues to suffer from severe acid deposition, despite the government implying a series of policies to control air pollution. In this study, rainwater samples were collected from 2011 to 2016 in Sichuan province to measure the pH values and the concentrations of nine inorganic ions (SO 4 2−, NO 3 −, NH 4 +, Cl−, Na+, Ca2+, K+, Mg2+, and F−), and then to investigate their spatiotemporal variations. Besides, the dominant sources for the acidic ions in the precipitation were also revealed by statistical model. The results showed that the rainwater continued to be highly acidic, and the Volume-Weighted Mean (VWM) pH value was calculated to be 5.18 during 2011 and 2016. NH 4 +, Ca2+, NO 3 −, and SO 4 2− were the dominant water-soluble inorganic ions, accounting for 79.2% of the total ions on average. The remarkable decrease in NO 3 − and SO 4 2− concentrations (from 75.9 to 54.3 μeq L−1 and from 285 to 145 μeq L−1, respectively) resulted in an increase in the pH value of rainwater from 5.24 in 2011 to 5.70 in 2016. The concentrations of SO 4 2−, NO 3 −, F−, Na+, and K+ showed remarkably seasonal variation, with the highest value observed in winter, followed by spring and autumn, and the lowest value observed in summer. High VWM concentration of these ions in winter were mainly due to adverse meteorological conditions (e.g., rare rainfall, lower planetary boundary height, and stagnant air) and intensive anthropogenic emissions. SO 4 2−, NO 3 −, and F− ions peaked in the southeastern Sichuan province, which is a typical industrial region. NH 4 + concentrations decreased from 268 μeq L−1 in the east to 10.4 μeq L−1 in the western Sichuan province, which could be related to the development of agriculture in the eastern Sichuan province. Ca2+ peaked in southeastern Sichuan province due to intensive construction activities and severe stone desertification. On the basis of Positive Matrix Factorization (PMF) analysis, four sources of inorganic ions in rainwater were identified, including anthropogenic source, crust, biomass burning, and aging sea salt aerosol. Geographically Weighted Regression (GWR) was used to find the spatial correlations between the socio-economic factors and ions in the rainwater. At the regional scale, the influence of fertilizer consumption and Gross Agricultural Production (GAP) on NH 4 + increased from east to west; moreover the influence of Gross Industrial Production (GIP) on SO 4 2− and NO 3 − also increased. Image 1 • SO 4 2− and NO 3 − ions concentrations decreased during 2014–2016. • Rainwater acidity was neutralized by high concentrations of Ca2+ and NH 4 +. • SO 4 2−, NO 3 − and F− ions peaked in the southeastern of Sichuan province. • The influence of Total Energy Consumption on SO 4 2− increased from east to west. Remarkable decreases of SO 4 2− and NO 3 − in the rainwater in Sichuan province was related to decreasing SO 2 and NO 2 emissions caused by implementation of pollutant control strategies. [ABSTRACT FROM AUTHOR]