  Aims. In the context of black-hole accretion disks, we aim to compute the
plasma-environment effects on the atomic parameters used to model the decay of
K-vacancy states in moderately charged iron ions, namely Fe ix - Fe xvi.
Methods. We used the fully relativistic multiconfiguration Dirac-Fock (MCDF)
method approximating the plasma electron-nucleus and electron-electron
screenings with a time-averaged Debye-Huckel potential. Results. We report
modified ionization potentials, K-threshold energies, wavelengths, radiative
emission rates, and Auger widths for plasmas characterized by electron
temperatures and densities in the ranges $10^5$ - $10^7$ K and $10^{18}$ -
$10^{22}$ cm$^{-3}$. Conclusions. This study confirms that the high-resolution
X-ray spectrometers onboard the future XRISM and ATHENA space missions will be
capable of detecting the lowering of the K edges of these ions due to the
extreme plasma conditions occurring in accretion disks around compact objects.
