Learn Hardcore Spanish (Latin America): En una charla ecológica explicaron que la contaminación también afecta la economía local. - In an environmental talk they explained that pollution also affects the local economy.

It is less formal than conferencia or discurso, but in context (a school, community center, NGO, etc.) it can still be a prepared, serious presentation.
In Latin America, charla is widely understood.
- In Mexico and some areas, you may also hear plática with a very similar meaning.
So en una charla ecológica is like saying “in an environmental talk / in a talk about ecology.”

Why is it en una charla and not a una charla or durante una charla?

En here is close to “in / at / during” in English.

En una charla = in a talk / at a talk (a general, very common way to set the scene).
You could also say:
- Durante una charla ecológica… = During an ecological talk… (slightly more explicit about time).
But a una charla would usually mean “to a talk” (movement or direction), as in:
- Fuimos a una charla ecológica. = We went to an ecological talk.

So en una charla is the natural choice for “In an ecological talk, they explained that…”

Who is explicaron referring to? There’s no subject pronoun like ellos or ellas.

Explicaron is the third person plural preterite of explicar (to explain).

(Ellos / ellas / ustedes) explicaron = they explained / you (plural) explained.
In Spanish, subject pronouns are often dropped because the verb ending already tells you the person and number.
So:
- En una charla ecológica explicaron…
  = In an ecological talk they explained…
  (we infer “they” from context: the speakers, organizers, experts, etc.)

You don’t need to say ellos explicaron unless you want to emphasize they, or contrast with someone else.

Why is explicaron in the past tense but afecta in the present tense?

This is very typical in Spanish reported speech.

Explicaron (preterite) refers to a finished event in the past:
- They explained (at that talk).
Afecta (simple present) expresses a general truth that is still valid now:
- Pollution affects the local economy (in general, as a fact).

So the structure is:

They explained (in the past) that pollution (still, in general) affects the local economy.

If you said afectaba (imperfect) instead, it would sound more like “was affecting” or talk about a situation specifically in the past, not necessarily a timeless fact.

Why do we need que after explicaron? In English we can often drop “that” (“they explained (that) pollution…”).

In Spanish, que here is obligatory.

Explicaron que la contaminación también afecta la economía local.
= They explained that pollution also affects the local economy.

You cannot omit que in this kind of noun clause:

❌ Explicaron la contaminación también afecta… (incorrect)
✅ Explicaron que la contaminación también afecta… (correct)

So think of que as the linking word that introduces what they explained.

Why is it la contaminación and not just contaminación without the article, like English “pollution”?

Spanish uses the definite article (el, la, los, las) much more often than English when talking about things in a general or abstract way.

La contaminación = pollution in general (not a specific instance).
English usually drops “the” for generic, uncountable nouns:
- Pollution affects the local economy.
  but Spanish prefers:
- La contaminación afecta la economía local.

Similarly:

La educación es importante. = Education is important.
La música me relaja. = Music relaxes me.

So la contaminación is the normal, natural choice for “pollution (in general).”

What does charla ecológica literally mean? Why is ecológica after charla, not before?

Literally:

charla = talk
ecológica = ecological / related to ecology

So charla ecológica = “ecological talk”, more naturally “an environmental talk”.

In Spanish, adjectives usually come after the noun:

charla ecológica (talk ecological)
economía local (economy local)
café caliente (coffee hot)

Putting the adjective before the noun is possible but changes style, nuance, or meaning, so the neutral, default order is noun + adjective.

Could we also say una charla sobre ecología instead of una charla ecológica? Is there a difference?

Yes, you can say both, and both are natural:

una charla ecológica
– Focus on the type of talk (an “ecological” talk, environmentally themed).
una charla sobre ecología
– Literally “a talk about ecology”, more explicit about the content/topic.

In most contexts, they are interchangeable; sobre ecología simply spells out the subject a bit more clearly.

What does también do in the sentence, and can it go in other positions?

También means “also / too / as well.”

Here:

…explicaron que la contaminación también afecta la economía local.

It suggests that pollution has other effects already known or mentioned, and in addition it affects the local economy.

Possible positions:

La contaminación también afecta la economía local. (most common)
También la contaminación afecta la economía local. (emphasizes “even pollution / pollution too”)
La contaminación afecta también la economía local. (slight shift in rhythm; still “also affects”)

The sentence given La contaminación también afecta la economía local is the most neutral, natural word order.

Why is it afecta la economía local and not afecta a la economía local?

Afectar usually takes a direct object without the preposition a:

afectar algo / a alguien
- La contaminación afecta la economía. (thing → no a)
- La contaminación afecta a las personas. (people → a appears because of the “personal a” rule)

General pattern:

For things:
- Esta decisión afecta el presupuesto.
For people/living beings that are specific:
- Esta decisión afecta a los empleados.
- El ruido afecta a los perros.

So afecta la economía local is correct and natural, with no a because la economía local is not a person.

What does economía local mean, and why is local after economía?

economía = economy
local = local

So la economía local = “the local economy.”

As with charla ecológica, Spanish generally uses noun + adjective:

economía local (economy local)
mercado local (market local)
cultura local (culture local)

English adjectives usually go before the noun; Spanish adjectives generally follow it.

Why are contaminación and economía spelled with accents (contaminación, economía)? What do those accents indicate?

The written accents (tildes) show where the stress (spoken emphasis) goes and also follow spelling rules:

contaminación
- Ends in -n, so normally stress would fall on the second-to-last syllable (contamina-).
- But the real stress is on the last syllable -ción: con-ta-mi-na-CIÓN.
- The accent mark on ó shows that final syllable stress.
economía
- Ends in a vowel, so normal stress would be on the second-to-last syllable: eco-no-*MI-a* (actually this one matches the rule if we count syllables correctly?).
- In fact, it’s four syllables: e-co-no-MÍ-a; the accent on í marks the stressed syllable explicitly.

In practice, you just need to learn that many nouns ending in -ción (contaminación, educación, información) and -ía (economía, energía, biología) carry an accent to show the correct stress.

Why are contaminación, charla, and economía all feminine (with la)? How do I know their gender?

Grammatical gender in Spanish is largely lexical: you must learn it with the noun.

In this sentence:

la contaminación – feminine
una charla – feminine
la economía – feminine

Common patterns (not 100% but helpful):

Words ending in -ción / -sión are almost always feminine:
- la contaminación, la educación, la información
Many nouns ending in -a are feminine:
- la charla, la casa, la mesa
Many nouns ending in -ía are feminine:
- la economía, la biología, la energía

Because they are feminine, adjectives and articles must agree:

la contaminación ecológica
una charla ecológica
la economía local