Blue curacao is orange-flavored and would taste super-awful with salt, kelp, and...whatever it is sea prunes taste like. Unless you meant for air? I was thinking some of the lighter, flowerier-tasting liqueurs, like St. Germain, mixed with something very clean to cut the sweetness (tonic? club soda? definitely gotta be bubbles), and served over ice with a lime garnish.

For fire: Cinnamon (which is what Fireball is), horseradish, or chili infusion. I have no idea what would necessarily go with any of those because I am a huge wimp about things that hurt to consume.

Earth: Served on the rocks, of course. :P Something like almond and anise mixed, maybe with a bit of a cinnamon liqueur. Lemon garnish? Beef it up with vodka for that "I just got hit by a boulder" feeling.