The total quantity or weight of organisms in a given area or volume 

The using up of a resource

The strength and vitality required for sustained physical or mental activity 

a device that produces a continuous electric directly from the oxidation of a fuel, as that of hydrogen by oxygen. 

Of, relating to, or produced by the internal heat of the earth 

Of or relating to the nucleus of an atom 

The presence in or introduction into the environment of a substance or thing that has harmful or poisonous effects 

The ability to do something or act in a particular way, esp. as a faculty or quality 

Of, relating to, or determined by the sun