All Figures

	Figure 1: Comparison between EWs measured from the spectrum of HD 180711 and those from Boyarchuk et al. (1996). Upper panel: EWs from Boyarchuk et al. (1996); lower panel: our determinations.
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In the text

	Figure 2: Comparison between the temperatures derived in the present work and those derived by Gray & Brown (2001) - open squares, Blackwell & Lynas-Gray (1998) - solid circles, Alonso et al. (1999) - solid triangles, Strassmeier & Schordan (2000) - open circles, and Soubiran et al. (1998) - solid squares.
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In the text

	Figure 3: Derivation of from the Ca I 6162 Å  profile for HD 180711.
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In the text

	Figure 4: Comparison between the observed spectrum for HD 90633 and the synthetic one with the Li abundances log A(Li) = 1.0, 1.85, and 2.1.
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In the text

	Figure 5: Comparison between the observed spectrum for HD 94084 and the synthetic one with the C abundances log A(C) = 8.36, 8.46, and 8.56.
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In the text

	Figure 6: NLTE profile fitting for HD 162076 (for the line Na I 5683 Å) and the LTE profile (dashed line).
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In the text

	Figure 7: Same as Fig. 6, but for the lines Na I 6164, 6160.
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In the text

	Figure 8: Same as Fig. 6, but for the lines Mg I 4703.
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In the text

	Figure 9: Same as Fig. 6, but for the lines Mg I 5173, 5184.
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In the text

	Figure 10: Carbon abundance [C/Fe] vs. [Fe/H].
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In the text

	Figure 11: Nitrogen abundance [N/Fe] vs. [Fe/H].
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In the text

	Figure 12: Comparison of our carbon abundances (open circles) and those of Kjrgaard et al. (1982) (asterisks) and Lambert & Ries (1981) (filled circles).
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In the text

	Figure 13: Oxygen abundance [O/Fe] vs. [Fe/H].
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In the text

	Figure 14: Sodium abundance [Na/Fe] vs. [Fe/H].
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In the text

	Figure 15: Sodium abundance [Na/Fe] vs. .
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In the text

	Figure 16: Sodium abundance [Na/Fe] vs. nitrogen abundance [N/Fe].
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In the text

	Figure 17: Magnesium abundance [Mg/Fe] vs. [Fe/H].
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In the text

	Figure 18: Calcium abundance [Ca/Fe] vs. [Fe/H].
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In the text

	Figure 19: Silicon abundance [Si/Fe] vs. [Fe/H].
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In the text

	Figure 20: Nickel abundance [Ni/Fe] vs. [Fe/H].
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In the text

	Figure 21: Comparison of the theoretical tracks and predictions for surface abundance variations with observations. Position of our target stars with [Fe/H]<-0.15 in the H-R diagram.
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In the text

	Figure 22: Same as Fig. 21 for [Fe/H]=0. Top right panel: the solid lines are those assuming an initial [C/Fe] equal to solar, while the dotted lines are obtained by simply shifting the previous ones by -0.15.
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In the text

	Figure 23: Same as Fig. 22 for [Fe/H]=0.252 and [C/Fe]=-0.20.
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In the text

	Figure 24: Predictions for surface abundance variations of O during the first dredge-up for the [Fe/H]=0 models, and comparison with the observations.
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In the text

	Figure 25: Li abundance log A(Li) vs.   for our sample stars compared with the theoretical predictions for the tracks at [Fe/H]=0. The line with the strongest Li depletion corresponds to the 1.0 model.
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In the text