  The Cherenkov Telescope Array (CTA) will provide very-high-energy (VHE; >~30
GeV) gamma-ray spectra of unprecedented resolution over a large energy range.
It is likely that, at least for bright sources, spectral features will be
revealed that cannot be distinguished with the current generation of Cherenkov
telescopes. We are investigating the capability of the CTA to detect spectral
signatures in TeV bright BL Lac objects that could reveal the emission from a
population of relativistic protons in those sources. Such a detection would be
crucial for the long-standing question of the origin of extragalactic cosmic
rays. As a first step, the expected VHE emission from hadronic scenarios is
compared to the spectral features that might arise in the more commonly assumed
leptonic scenarios for a given source. We also evaluate the impact of different
array configurations on the detectability of such features.
