Map of the log([N II]/Hα) ratio in the central areas of ESO 338, highlighting the features showing the increase in the [N II]/Hα ratio. A v-shaped feature (B) as well as a circular blob (A) are seen north of the starburst clusters, while a fainter elongated feature (C) can be seen extending to the south. Overlayed in blue (−30, −20, −10, 0 km s⁻¹) and red (10, 20, 30 km s⁻¹) contours is the velocity field of the [N II] 6583 Å line. The eastern leg of feature B shows a strong blue shifted emission, which is not seen in Hα. The white asterisk is the possible location of the responsible cluster for the nitrogen enrichment.