The present study reports plasma temperatures and electron number densities for a Microwave Induced Plasma (MIP) source produced in an axially-varied bore discharge tube. Observed temperatures and electron number densities exhibit significant increase, but decrease of argon emission intensity, upon the aqueous sample introduction. Experimental results suggest that local thermodynamic equilibrium is not consistent and excitation and ionization of atomicspecies due to collision with high energy electron is dominant under the operating conditions employed for the measurements.