What is breathable air and its connection with lakes?

Answer 1

For human beings breathable air consists of a ratio of oxygen to some inert gas (on earth it is nitrogen). The typical concentration is about 1/5th oxygen and 3/4 nitrogen.

Where does oxygen come from? Oxygen readily combines with so many different elements. Hydrogen + oxygen makes water. Carbon plus oxygen makes carbon dioxide. Iron plus oxygen makes rust. Silicon combines with oxygen to make sand. So free atmospheric oxygen is an oddity. Why do we have such an abundance of it?

This question brings us to lakes. More particularly, oceans. Earth's early oceans teemed with single celled organisms that absorbed carbon dioxide from the atmosphere or that was dissolved in sea water, and using sunlight broke that molecule apart, releasing the oxygen. After eons these photosynthetic creatures tore apart most of the atmospheric CO2, rendering it into carbon, which they absorbed and used, and releasing the oxygen.

After several billion years photosynthetic plants evolved, first in the oceans, and then migrating into the terrestrial sphere (land). But even today most new oxygen come from marine cyanobacteria, mostly in the ocean, but also in lakes and rivers, and to some extent pine needles, leaves on trees and bushes, blades of grass, and ferns.

Answer 2

Breathable air is air that contains enough oxygen for humans to breathe comfortably. Lakes play a vital role in producing breathable air through a process called photosynthesis, where aquatic plants in the lake absorb carbon dioxide and release oxygen. This oxygen then gets transferred into the surrounding air, contributing to the overall air quality.