Identify a chemical that is used to counteract the effects of acid precipitation on aquatic ecosystems.

Calcium carbonate

Explanation:

The chemical most commonly used to counteract the effects of acid precipitation on aquatic ecosystems is calcium carbonate.

Acid rain or acid deposition or acid precipitation is any form of precipitation with an elevated level of hydrogen ion concentration in them.

To nullify this acidic precipitation in aquatic ecosystem, we need to use an environmentally friendly alkaline agent.

The most desired is calcium carbonate. The carbonate neutralizes the acid by producing carbon dioxide, water and calcium salts.