You can use Zotero on the iPad browser by installing a "Bookmarklet," a special link that saves items directly to your Zotero account on the web.
You must have a Zotero account, and your iPad must be online, to use Zotero.
When you're on a page with a citation, select the Save to Zotero bookmark. The iPad browser will save the citation directly to your Zotero library online.
For more information, see the Zotero for Mobile documentation page.