"P van Rijckevorsel" wrote in message .. .
Jelena schreef
Besides, in a surface layer of lake sometimes
I got negative values of concentration of chl a (?) and I am wondering
how it is possible to get negative value, minimal concentration should
be zero, not less then zero.

+ + +
Obviously, if you are measuring negative concentrations you are doing
something wrong. More likely in your calculations than in your measurements,
but who knows ...
PvR

That is first what I had in my mind - wrong calculation, but formula
is OK actually, it is ISO method that I use. Unbelivable things
sometimes can happen in science, isn't it? Thanks anyway, if you have
more sugestions you are very welcome, I really need help!

"Jelena" skrev i en meddelelse
om...
I am making investigation of Scadar Lake phytoplankton (Balcan region)
and in a lot of samples for chlorophyll analyzes I got results that I
am not able to explain. For example, I got increasing of chlorophyll
concentration with depth and I don't know how to explain that, because
I expected the opposite. Besides, in a surface layer of lake sometimes
I got negative values of concentration of chl a (?) and I am wondering
how it is possible to get negative value, minimal concentration should
be zero, not less then zero. I am newcomer in this field, so please if
someone can help me about this subject, I will be very grateful!

When the algae and cyano bacteries die they sink to the bottom, but the
chlorophyll remains and is mesureable several days after. Therefore the
increasing concentration of chlorophyll under certain circumstances.

Poul Evald Hansen