How do I get Riddler trophies blocked by steam jets?

I'm exploring the Steel Mill zone, and I've found 2 Riddler trophies behind steam jets that I can't seem to deactivate. One is in the Assembly Line area, near some bumper cars, and the other is in the Loading Bay, in an area beneath an arena where I fought some of Joker's thugs.

How can I get past this steam, or retrieve the trophies without turning it off?

Use a freeze blast to stop the steam. That should allow you to get past both of the mentioned areas.

You need to get the freeze grenade from Mr Freeze before you can stop the steam jets. This is obtained during the course of the game, so if you can't get past them yet, come back later.

Source: GameFAQs page, not linked to a single FAQ but there should be enough info in any of them.