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Re: nutrients in natural waters (was random question)


D0NxD0N wrote:

> i was talking to someone on aol yesterday and he had this to
> say about having a nitrate of 10 ppm-
>
> <<<<Also, the nitrate levels in natural eco-systems (be it the Amazon River or
> the tropical reef) are near 0 ppm.  A well-balanced ecological system will use
> nearly all of the available nutrients.  Excess nutrients is an indication of
> an out of balanced biological system.  10 ppm of nitrate would only be found
> in polluted waters.>>>>
>
> is this true?? ive heard some people say that zero nitrates in a planted tank
> isnt necessarily a good thing and a nitrate level of 10 ppm or less is good
> for the plants.
>

He's right.

In well-lit open water environments the competition for nutrients usually
keeps nitrate levels down to very low numbers.  I have in front of me a
large table of water quality data for selected rivers.  Not suprisingly,
the selected rivers are mostly in Europe, the US and Canada - certainly
the list includes polluted rivers.

There are no values on the table over 10.  The highest is 9.6 for the Rio
Guadalquivir (Spain) in 1980.  Streams in largely undeveloped areas have
very low nitrate levels; e.g. the Mackenzie in Canada is listed with an
average nitrate of 0.10 mg/l.  More typically, the values are around 2
mg/l.

The table doesn't indicate that the values are nitrate as N, so I believe
from the title that it is cited as nitrate.

You shouldn't be too surprised to find out that (by the standards applied
to natural waters) aquarium water is usually polluted.  In unpolluted
water that supports good plant growth, plant nutrients are either common
solutes (e.g. sulfate, magnesium, potassium) or available at low
concentrations (but steady supplies) as part of the natural nutrient
cycles in a biologically active substrate (e.g. nitrogen, phosphorus,
iron).

You would have a hard time maintaining a heavily planted aquarium under
near natural conditions.  Our usual aquarium methods are very unnatural
but when they're done right, they work.


Roger Miller