What is it you’re trying to block? Your original post spoke of links to your website, it’s impossible to prevent sites from linking to you. IP blocks will achieve nothing. You might not have expected to see inbound links or traffic from those URLs, but they’re doing no harm to you at all.
The titles of the pages linking to you are stored in the Google search cache too, it’s a Turkish storage tank manufacturer which at some point was compromised and held a bunch of Korean pages about call girls:
Akismet deals with spam on your Discourse installation, this isn’t a Discourse problem though, it’s not really a problem in any sense of the word. The data exists in search engines like Google. You’re objecting to words which appear on another site, spotted by a crawler service, nobody else will ever see them.