Dew formation takes place when atmospheric water vapor condenses on the surface which cools down due to radiation deficit. As it is a local phenomenon, its study gives information about the pollutants present in the atmosphere. Also, since dew formation is a natural phenomenon, and involves passive cooling, this can be a potential method for atmospheric water harvesting. The main intention of this present research work was the collection of dew samples and their analysis for yield and chemical composition. Dew samples were collected on a self-fabricated dew collection set up during the winter season. In total 30 dew samples were collected and analyzed for ionic constituents. The results were then compared to those of rain samples. The pH of dew was found to be in the range of 7-8.7, showing the neutral to alkaline nature of dew. Ionic compositions were higher in dew than in rain. While sulfate largely contributed to the ion composition of dew, nitrate was the least contributing ion. The average concentration for sulfate and nitrate in dew were found to be 0.55 and 0.03 meq/L, respectively. The average yield of dew was found to be 0.13L/m2. This yield value from the simplest of collection set-up ensures that dew can be considered as the potential water source with advanced condensing material and passive/active cooling in arid and semi-arid regions.
Keywords: Dew; atmospheric water; chemical composition; dry deposition; regional air pollution.