In order to study the influence of the impurity sources on line emissions, gas fuelling experiment were performed with controlled CD4 gas inlet into the inner and outer Private Flux Region (PFR) as well into the outer Scrape-Off Layer (SOL). Comparison discharges were performed with D2 injection into the outer SOL, with the same deuterium source rate as for the CD4 pulse. Changes in the divertor spectroscopic signals have been analysed and show a similar behaviour for CD, CII and CIII emission during the inner divertor fuelling into either SOL or PFR, indicating that these signals are independent of the location of methane sources. In contrast to the inner divertor puffing, CD4 fuelling into the PFR of the outer divertor shows the strong dependence of CD-emission on the magnetic field configuration. The evolution of carbon impurity profiles in L-mode discharges will be discussed, with respect to its dependence on the location of methane fuelling (inner/outer divertor leg) and on the position of the strike points.