Tangible usually means you can touch something. For example, Air is not tangible, but is still part of the physical environment. 

If you're wondering about using English words, the website StackExchange/English would be useful for you, more so than ResearchGate. 

http://english.stackexchange.com/

Hello Dear, like mention before for John about Tangible mean you can be touch it, Also is use for countable purpose.  " Physical is more  relating to that which is material:

the physical universe; the physical sciences."(from Dictionary.com). for that reason you are writing about Physical Environment .   From my point of view Physical is more deep relate to material and Tangible to monetary purpose.

Hi,

Physical environment is related to the resources of the three spheres (hydrosphere, atmosphere, lithosphere), however, tangible environment is related to the quality of the environmental system (air quality, water quality, soil quality etc). Thus, tangible environemt implies the bio effect (poitive or negative) on any physical system (3-spheres).