THE EFFECTS OF CLUSTER ENVIRONMENT ON THE CHEMICAL EVOLUTION OF GALAXIES .2. NGC4254

We present new long-slit spectrophotometric measurements of 10 giant H II regions located in the Virgo spiral NGC 4254. Gradients in the emi ssion-line ratios log R(23), log[N II]/[O II] and log[S II]/[O II] are observed and provide the constraints fora photoionization analysis to determine disc abundance patterns for O/H, N/H and SIH. We find that log O/H + 12 = 9.52( +/- 0.1)- 0.27( +/- 0.05) p/p(eff); log NIH = 8.6 2(+/-0.1)-0.38(+/-0.05)p/p(eff); and log S/H=7.70(+/-0.1)-0.27(+/-0.05 )p/p(eff). Adopting a distance of 18 Mpc to NGC 4254, the slopes becom e -0.06, -0.08 and -0.06 dex kpc(-1), respectively. The value of log O /H at the nucleus indicates that the disc of NGC 4254 has a very high metallicity relative to other spirals in its morphological class. We o bserve a rapid rise in metallicity as the gas fraction decreases near the nucleus, perhaps providing evidence for metallicity-sensitive nucl eosynthesis. In addition, our models indicate that the stellar effecti ve temperature and the log of the ionization parameter are constant ac ross the disc at 35 500+/-3000 K and -2.9+/-0.3, respectively. Combina tion of information on gas distribution with our abundance results sug gests that the O and S abundance patterns are best described by a simp le model of chemical evolution with relatively constant yields near th e solar mass fractions for these elements. The results for N imply som e secondary contribution to its build-up.