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We measured the metallicity Z in the broad emission line regions (BELRs) of43 SDSS quasars with the strongest N IV] and N III] emission lines. TheseN-Loud QSOs have unusually low black hole masses. We used the intensity ratioof N lines to collisionally-excited emission lines of other heavy elements tofind metallicities in their BELR regions. We found that 7 of the 8line-intensity ratios that we employed give roughly consistent metallicities asmeasured, but that for each individual QSO their differences from the mean ofall metallicity measurements depends on the ionization potential of the ionsthat form the emission lines. After correcting for this effect, the differentline-intensity ratios give metallicities that generally agree to within the0.24 dex uncertainty in the measurements of the line-intensity ratios. Themetallicities are very high, with mean log Z for the whole sample of 5.5 Z_sunand a maximum of 18 Z_sun. Our results argue against the possibility that thestrong N lines represent an overabundance only of N but not of all heavyelements. They are compatible with either (1) the BELR gas has been chemicallyenriched by the general stellar population in the central bulge of the hostgalaxy but the Locally Optimally-emitting Cloud model used in the analysisneeds some fine tuning, or (2) that instead this gas has been enriched byintense star formation on the very local scale of the active nucleus that hasresulted in an abundance gradient within the BELR.

The Metallicities of the Broad Emission Line Regions in the Nitrogen-Loudest Quasars