Fosfatul este un parametru al apei.

-ul is the definite article attached to the end of the noun. Romanian usually puts the at the end of the word, not before it.

• fosfat = phosphate
• fosfatul = the phosphate

In this sentence, fosfatul can also be understood in a generic/scientific sense, not necessarily one specific sample of phosphate. Romanian often uses the definite form for general statements like this, where English might simply say phosphate.

So Fosfatul este... can mean something like:

• Phosphate is...
• or more literally The phosphate is...

depending on context.

Este means is. It is the 3rd person singular present form of a fi (to be).

So:

• eu sunt = I am
• tu ești = you are
• el/ea este = he/she/it is

In everyday Romanian, you may also hear e instead of este:

• Fosfatul este un parametru al apei.
• Fosfatul e un parametru al apei.

Both are correct; e is just shorter and more common in speech.

Because the sentence is classifying phosphate as one parameter among others, not identifying it as a unique, already-known parameter.

• un parametru = a parameter
• parametrul = the parameter

So:

• Fosfatul este un parametru al apei. = Phosphate is a parameter of water / a water parameter.

If you said parametrul, it would sound like:

• Phosphate is the parameter of the water

which suggests one specific parameter and would usually not fit the intended meaning.

Al is part of a Romanian structure used to show a relationship like of.

In un parametru al apei, it links parametru and apei, giving the meaning:

• a parameter of the water

This is called the genitival/possessive article. Its form changes depending on the noun it refers to:

• al – masculine/neuter singular
• a – feminine singular
• ai – masculine plural
• ale – feminine/neuter plural

Because parametru is masculine singular, Romanian uses al:

• un parametru al apei

Because after al, Romanian normally uses the genitive form.

Here are the relevant forms:

• apă = water (basic form)
• apa = the water (nominative/accusative)
• apei = of the water / to the water (genitive/dative)

So:

• al apei = of the water

That is why the sentence has apei.

Romanian can use de in many expressions, but here the structure is specifically noun + al/a/ai/ale + genitive noun.

So the natural phrasing is:

• un parametru al apei

not normally:

• un parametru de apă

The version with al apei expresses belonging or relation: a parameter of water / a water-related parameter.

In technical language, this is a normal and natural structure.

In a sentence like this, it often refers to phosphate in general, especially in a scientific, technical, or definitional context.

Romanian often uses the definite singular to talk about a whole class or concept:

• Leul este un animal puternic. = The lion is a strong animal / Lions are strong animals.
• Fosfatul este un parametru al apei. = Phosphate is a water parameter.

So even though fosfatul is formally the phosphate, the practical meaning can be more general than in English.

Yes. In technical or environmental contexts, it is natural.

It means something like:

• a parameter of water
• a water parameter
• a water-quality parameter

Depending on context, English may translate it less literally. Romanian often keeps the of the water structure where English might prefer an adjective-like noun phrase such as water parameter.

Yes, but the original order is the most neutral:

• Fosfatul este un parametru al apei.

Romanian word order is fairly flexible, and changing it usually changes the focus or emphasis.

For example:

• Un parametru al apei este fosfatul.

This still makes sense, but now the sentence emphasizes fosfatul as the thing being identified.

So both are possible, but the original version is the straightforward, standard way to say it.

A simple English-friendly approximation is:

• fos-FA-tul ES-te un pa-ra-ME-tru al a-PEY

A few helpful notes:

• fosfatul → stress on fat
• este → usually like ES-te
• parametru → stress on me
• apei → sounds roughly like a-PEY

Romanian spelling is fairly phonetic, so once you know the sound rules, pronunciation is usually predictable.