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Over exploitation of groundwater in Changping District of Beijing city has caused serious land subsidence in the past decades. In recent years, the operation of the South-to-North Water Transfer Project has reduced the land subsidence rate. In this paper, Experimental tests are performed using the GDS Consolidation Testing System to characterize the compression and rebound of soils at depths of less than 100 m caused by groundwater withdrawal and recharge in Changping District. The results indicate that the compressible layers are the main contributors to land subsidence. The first compressible layer experiences greater deformation and more considerable hysteresis than the other compressible layers with the same decrease in the pore water pressure. Therefore, the exploitation of the adjacent aquifer should be controlled in the future. The deformation in the second and third compressible layers is a gradual and long-term process with little rebound; therefore, the subsidence should be seriously addressed when the groundwater in the two compressible layers is exploited on a large scale. In the same compressible layer, silty clay is more compressible and hysteretic than silt. For the same soil sample, the deformation rate decreases gradually as the pore water pressure decreases, whereas the creep deformation shows an overall increasing trend. A parameter named the subsidence index Cw is proposed in this paper to describe the soil compressibility during groundwater withdrawal. All the soil samples are characterized by elastic-plastic deformation, and the shallow soil samples with less pore water pressure decrease are more likely to rebound. [ABSTRACT FROM AUTHOR]

As a top ambient pollutant in urban area, fine particulate matter (PM 2·5) has been associated with the occurrence and deterioration of many medical conditions, while few studies have observed the association with psychiatric conditions. We aimed to investigate the association between short-term PM 2·5 exposure and psychiatric emergency events, and further explored the variation by age, sex, and seasonal patterns, which have been suggested to be associated with both psychiatric risk and pollutant toxicity. We used time-series analysis to investigate the association between short-time exposure (0–3 days) of PM 2·5 and emergency ambulance dispatches for psychiatric emergencies in Beijing, one of the most polluted cities in China during the study period. We did stratified analyses to examine the effects of age, sex, and seasonal pattern. Between 2008 and 2014, 158 634 psychiatric emergencies were recorded. Every 10 μg/m3 increase of the PM 2·5 concentration was associated with a 0·12% increase of the same-day overall psychiatric emergencies (95% CI 0·03–0·22; p=0·013) and a 0·12% increase of the suicide-related psychiatric emergencies at lag 2 (2 days after PM 2·5 exposure; 0·01–0·24; p=0·041). The associations remained when adjusted for sunlight duration. The age effect that children (<18 years) were more likely to be involved in suicide-related psychiatric emergencies after PM 2·5 exposure than adults (18–64 years) was significant (percentage change for children vs adults of 0·84% vs 0·07% at lag 3; p=0·013). No significant association was found among the older population (≥65 years; p=0·050–0·825). However, sex and seasonal effects were not statistically significant on the PM 2·5 and psychiatric emergencies association (p=0·052–0·999). We found a positive association between acute PM 2·5 exposure and increased psychiatric emergency presentations as indicated by emergency ambulance dispatches data. Children were more vulnerable to acute PM 2·5 elevation and developed psychiatric problems, especially suicide. We suggest that preventive attention for psychiatric emergencies should be paid after acute PM 2·5 elevation, particularly to children. National Natural Science Foundation of China (81801344), China Postdoctoral Science Foundation (189826), Postdoctoral Fellowship of Peking-Tsinghua Center for Life Sciences, and the Swedish Research Council (2015-06372). [ABSTRACT FROM AUTHOR]

As a top ambient pollutant in urban area, fine particulate matter (PM 2.5) has been associated with the occurrence and deterioration of many medical conditions, while limited studies have observed the association with psychiatric conditions. This study aimed to investigate the association between short-term PM 2.5 exposure and psychiatric emergency events, and further explored the variation by age, sex and seasonal patterns, which have been suggested to be associated with both psychiatric risk and pollutant toxicity. We used time-series analysis to investigate the association between short-term exposure of PM 2.5 and emergency ambulance dispatches for psychiatric emergencies (EPE) (n = 158634) in Beijing, one of the top polluted cities in China during the study period between 2008 and 2014. Stratified analyses were conducted to examine the effects of age, sex and seasonal pattern. Every 10 μg/m3 increase of the PM 2.5 concentration was associated with a 0.12% increase of the same-day overall EPE (95% CI: 0.03–0.22%, p = 0.013) and a 0.12% increase of the suicide-related EPE at lag 2 (95%CI: 0.01–0.24%, p = 0.041). The associations remained when adjusted for sunlight duration. An age effect was observed where children (age <18) showed a higher risk of suicide-related EPE after PM 2.5 exposure compared to adults (18 ≤ age≤64). We did not observe evidence of effect modification by sex and season based on the results of stratified analysis. We found a positive association between acute PM 2.5 exposure and increased psychiatric emergency presentations indicated by emergency ambulance dispatches data. Children were more vulnerable and might develop psychiatric problems including those leading to suicide. Public awareness of the health risks of PM 2.5 is important to strengthen current efforts to reduce emissions. • Increased PM 2.5 is associated with increased number of ambulance dispatches for psychiatric emergencies. • Children showed a higher risk of suicide-related emergency associated with PM 2.5 concentration compared to adults. • Intervention strategy should be developed to reduce PM 2.5 level and exposure particularly in the younger population. [ABSTRACT FROM AUTHOR]