The Variation in Chemical Composition and Source Apportionment of PM before, during, and after COVID-19 Restrictions in Zhengzhou, China.

Despite significant improvements in air quality during and after COVID-19 restrictions, haze continued to occur in Zhengzhou afterwards. This paper compares ionic compositions and sources of PM before (2019), during (2020), and after (2021) the restrictions to explore the reasons for the haze. The average concentration of PM decreased by 28.

Environmental risk-based hydroeconomic evaluation for alluvial aquifer management in arid river basin.

Groundwater has resource, ecology, economy and society attributes. In recent years, ecological degradation caused by intensive groundwater exploitation to support socio-economic development has been of growing concern in arid and semiarid regions. To protect the groundwater sustained ecosystem, this paper developed a novel environmental risk-based hydroeconomic model to evaluate the tradeoff between groundwater utilization and ecological environmental protection in Golmud river catchment of Qaidam basin, a typical inland river watershed and alluvial aquifer, in northwestern China.