Study on the Characteristics of Atmospheric Dry and Wet Deposition in the Upper Reaches of Baiyangdian

To study the characteristics of atmospheric dry and wet deposition in the upper reaches of Baiyangdian,two sampling sites in Baoding City were monitored for 1 year from September 2018 to August 2019.The results showed that the dry and wet deposition fluxes of total nitrogen(TN)during the monitoring period were 6.87 and 6.46 kg/(hm^(2)·a),respectively.The ratio of wet to dry deposition of TN was approximately 1∶1,with wet deposition being dominated by ammonium nitrogen deposition.The dry and wet deposition fluxes of total phosphorus(TP)were 0.228 and 0.125 kg/(hm^(2)·a),and it was dominated by dry deposition.The average concentration of TN in wet deposition exceeded the standard threshold for eutrophic waters,and its ecological effects on the Baiyangdian basin should be concerned.Wet deposition fluxes of nitrogen and phosphorus had a significantly positive correlation with rainfall,while their deposition concentrations were negatively correlated with rainfall.The dry deposition of atmospheric nitrogen and phosphorus was influenced by the amount of dustfall and climatic factors such as rainfall,temperature,and humidity,which mainly occurred from April to August.

Droplet Deposition Pattern Affected by Different Heating Directions

The coffee ring effect commonly exists in droplet deposition patterns,which fundamentally affects scientific research and industrial applications,like pharmaceutical purification,salt manufacturing,etc.Some researchers have tried different solutions to control the distributions of droplet deposition patterns,but most control deposits by adjusting droplet characteristics.In this work,droplet deposition patterns with different wettability are investigated by both localized and substrate heating.A whole process of droplet evaporation is recorded.The droplet generally evaporates from Constant Contact Radius(CCR)mode to Constant Contact Angle(CCA)mode,and CCR stage occupies the most of time.Experimental results show that,without any chemicals,laser induced local heating transitions particle deposition patterns from ring-like structure to dot-like patterns on a hydrophilic surface,driving most saline solvent to the center.Meanwhile,a hydrophobic surface is also investigated showing that the particles tend to assemble at the central area,but the pattern is slightly different compared to that on hydrophilic surface.In addition,physical mechanisms of local heating and heating from substrate are also explored.