What's the difference between uptake and adsorption of gas into aerosols
Adsorption is adhesion of thin film of liquid or gas on solid substance and the host solid substance does not form chemical bond with deposited material. Uptake is entering of material into substance, end product of which is a solution. Uptake generally happens in liquid host substances but it is also possible for solid host substance to uptake the gas or liquid. 

In context of aerosols, the term adsorption is used when solid aerosol particles like dust, soot, ice, etc. are interacting with gases. The term uptake is used when liquid aerosol particle are interacting with gases. 

Reference
http://glossary.ametsoc.org/wiki/Adsorption