heavy industry is manufactured goods such as machinery,mining equipment, and steel

In economics, to simplify, labor and capital. Light industry is labor intensive industry while heavy industry is focused on capital investment.

Because the heavy industry is polluting the water and air.

heavy water plant should be near to fertilizer industry because heavy water is also used in manufacturing fertilizers and pesticides.

The opposite of heavy industry would be light industry, which typically involves the production of small goods or consumer products that require less raw materials and energy to manufacture.