There is no single standard of title abbreviations. Some site translators may put alternative abbreviations in the short journal field. Zotero does not use ISI abbreviations for the auto-shortening feature, but rather NLM (this standard permits reuse).
https://www.zotero.org/support/kb/journal_abbreviations
and many title words are in:
http://www.issn.org/services/online-services/access-to-the-ltwa
including ionic->ion.