@topical_island et al: Look at the cards and identify the (1) activated abilities and (2) triggered abilities. You can tell two abilities are different because the text will be formatted into different lines or paragraphs. Moreover activated abilities are templated in the form "Cost: Effect" and triggered ability will start with "When, "Whenever," or "If."
Ex: Forbidden Orchard
T: Add one mana of any color to your mana pool.
Whenever you tap Forbidden Orchard for mana, target opponent creates a 1/1 colorless Spirit creature token.
Two lines, two abilities, one of them activated and one triggered.
Ex: City of Brass
Whenever City of Brass becomes tapped, it deals 1 damage to you.
Tap: Add one mana of any color to your mana pool.
Two lines, two abilities, one of them activated and one triggered. The order of the abilities is swapped for Reasons, but don't be fooled, these are still two distinct abilities.
Ex: Ancient Tomb
Tap: Add CC to your mana pool. Ancient Tomb deals 2 damage to you.
One line, one (activated) ability. The damage is part of the effect of activating the ability, and not a separate triggered ability.
Now, once you've identified the activated abilities, check if they're mana abilities. This means making sure (1) the ability could hypothetically produce mana (even if no mana would be produced in the current board state; Tolarian Academy's activated ability is a mana ability even if no artifacts are currently in play), (2) the ability doesn't target (so Deathrite Shaman's land exile ability is not a mana ability), and (3) it's not a loyalty ability (this is safe bet, unless you somehow turned Koth of the Hammer into a land.) Unless it's a mana ability, Blood Sun removes it.
Next, look at the triggered abilities. Triggered abilities can sometimes be mana abilities (Wild Growth) but I can't think of a single land that naturally comes with a triggered mana ability. Like with activated abilities, a triggered ability is only a mana ability if it (1) could generate mana and (2) doesn't target; in addition, the triggered ability must trigger off of activating another mana ability (Wild Growth), or adding mana to your mana pool (Caged Sun). Not a triggered mana ability? Blood Sun removes it.
Finally, not an activated or triggered ability? Blood Sun removes it. This includes replacement effects that modify how the land enters play (tapped, with counters, with a required sacrifice, etc), and as of the Ixalan rules changes, the removed replacement effects have no effect on the land entering play.