  The abundances of alkali elements (Li, Na, and K) were determined from the Li
I 6708, Na I 5682/5688, and K I 7699 lines by taking into account the non-LTE
effect for 24 sharp-lined A-type stars v sin i < 50 km/s, 7000 K < Teff <10000
K, many showing Am peculiarities to different degrees), based on
high-dispersion and high-S/N spectral data secured at BOAO (Korea) and OAO
(Japan). We found a significant trend that A(Na) tightly scales with A(Fe)
irrespective of Teff, which means that Na becomes enriched similarly to Fe in
accordance with the degree of Am peculiarity. Regarding lithium, A(Li) mostly
ranges between ~3 and ~3.5 (i.e., almost the same as or slightly less than the
solar system abundance of 3.3) with a weak decreasing tendency with a lowering
of Teff at Teff < 8000 K, though several stars exceptionally show distinctly
larger depletion. The abundances of potassium also revealed an apparent
Teff-dependence in the sense that A(K) in late-A stars tends to be mildly
subsolar (possibly with a weak anti-correlation with A(Fe)) systematically
decreasing from ~5.0 (Teff ~ 8500 K) to ~4.6 (Teff ~ 7500 K), while those for
early-A stars remain near-solar around ~5.0-5.2. These observational facts may
serve as important constraints for any theory aiming to explain chemical
anomalies of A-type stars.
