Learn Hardcore Portuguese (Portugal): O plástico reciclado ajuda a manter o ambiente limpo. - Recycled plastic helps keep the environment clean.

In European Portuguese you normally use the definite article before nouns even when speaking in general. So o plástico here means “plastic” as a material, not one specific piece. English often drops the article in such contexts, but Portuguese keeps it.

Why is reciclado placed after plástico, and why does it end in -ado?

Reciclado is a past participle used as an adjective, so it follows the noun it describes: plástico reciclado (“plastic that has been recycled”).
It ends in -ado because it agrees in gender and number with plástico (masculine singular). If you were talking about “recycled bottles” (garrafas), you’d say garrafas recicladas.

Why does the sentence say ajuda a manter instead of just ajuda manter?

In European Portuguese the verb ajudar when followed by another verb generally requires the preposition a plus the infinitive.
• Correct: ajuda a manter (“helps to keep”)
• Incorrect (in EP): ajuda manter
Some learners see English “helps keep” and try to drop a, but in Portugal you need it.

Why is there an o before ambiente? In English we say “keep the environment clean” or “keep environment clean.”

Just as with o plástico, Portuguese uses the definite article before ambiente when speaking of the environment in general: o ambiente = “the environment.” If you said manter ambiente limpo without the article, it would sound unnatural.

Why is ambiente singular here? Couldn’t we say ambientes limpos?

Ambiente in this phrase refers to the global environment (a mass/abstract concept), so it stays singular. Using the plural ambientes limpos would imply talking about several distinct “environments” (e.g., different rooms or ecosystems), which changes the meaning.

Why is limpo after ambiente, and why is it in the masculine singular form?

Limpo is an adjective that agrees in gender and number with ambiente (masculine singular).
When an adjective follows the noun as part of an object complement (here “keep the environment clean”), it remains in its matching form: ambiente limpo.

How do you pronounce plástico reciclado, and where is the stress?

In European Portuguese:
• plástico is [ˈplaʃ.ti.ku], stress on the first syllable PLÁ- (marked by the acute accent). The s before t is pronounced like [ʃ].
• reciclado is [ʁe.siˈkla.du], stress on -cla- (second syllable from the end). The initial r is a guttural [ʁ], typical of Portugal.

Could we use a different verb or structure, like contribui para manter?

Yes. Portuguese offers alternatives:
• O plástico reciclado contribui para manter o ambiente limpo.
Here contribuir para + infinitive means “contributes to keeping,” similar in meaning to ajudar a manter, but slightly more formal.