Abstract Making use of quasar spectra from LAMOST, in the spectral data around the Mg II emission lines, research described in this paper has detected 217 Mg II narrow absorption lines (NALs) with \(W^{λ2796}_r \ge 3σ_w\) and \(W^{λ2803}_r \ge 2σ_w\) in a redshift range of \(0.4554 \le z_{\rm abs} \le 2.1110\). For quasars observed by both LAMOST and SDSS, we find that 135 Mg II NALs were obviously observed in the LAMOST spectra, 347 Mg II NALs were were apparent in the SDSS spectra, and 132 Mg II NALs were clearly present in both the SDSS and LAMOST spectra. The missed Mg II NALs are likely ascribed to low signal-to-noise ratios of corresponding spectra. Among the Mg II NALs obviously observed in SDSS or LAMOST spectra, eight Mg II NALs were significantly changed with \(|\Delta W^{λ2796}_r| \ge 3σ_w\) in time intervals of \(\Delta {\rm MJD}/(1 + z_{\rm em}) = 359 - 2819 \) d.
Keywords line: identification — quasars: absorption lines — quasars: general
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