We discuss preliminary results of a comparison study of so-called stack-spectra calculated for Lyman-alpha forest within a redshift interval 2.04 ≤ z ≤ 3.43 and a radial distribution of C IV absorption systems calculated within an interval 1.56 ≤ z ≤ 2.25. A few samples of quasar (QSO) spectra from Sloan Digital Sky Survey were used for this analysis. We found that the stack-spectra, or Lyman-alpha absorption spectra averaged over a sample of 54,468 QSOs, incorporate a few quasi-periodical components relative to the comoving radial distance calculated for the ΛCDM cosmological model. Significant peaks in the power spectra correspond to the spatial comoving scale (104 ± 5) h^-1 Mpc (h=H₀/100 km s^-1 Mpc^-1, H₀ is the Hubble constant) and a few several-fold scales with respect to the first one. The radial distribution of 9,454 C IV absorption systems exhibits only one moderately significant (∼ 3σ) quasi-periodical component with a spatial comoving scale (113 ± 9) h^-1 Mpc, which is close to the basic quasi-period of the Lyman-alpha stack-spectra. Definite cross-correlation of both the radial distributions is also obtained. Possible relation between the quasi-periodical components revealed in this analysis and the phenomenon of the baryon acoustic oscillations is discussed.

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