Nonbiodegradable pollutants, such as certain chlorinated hydrocarbon pesticides (e.g.DDT) and heavy metals, such as lead, copper, and zinc in some industrial effluents, accumulate in the environment.
Casinghead gas is wet gas containing liquid hydrocarbons that can be removed from the gas by reducing the temperature or pressure on the gas with an absorption plant.
Its high-pressure steam drove the engine pistons in virtual silence, in contrast to clattering gas engines which emitted the aroma of burned hydrocarbons.