Chukchi Borderland Project

Daily Updates from

our Teacher at Sea


August 27

Nutrient Data Analysis

What does a "Nutrient Analyzer" do?  Good question.   This question was posed to Susan Becker from Scripps Institution of Oceanography.

Susan looks at four types of nutrients found in seawater: nitrate, nitrite, phosphate and silica.  These nutrients are used by phytoplankton.

Bacterosira Fragilis - an example
of phytoplankton found in the Arctic.


An example zooplankton, Copepod Calanus hyperboreus 
length ca. 20 mm, from Antarctica

Phytoplankton have two sources of energy for growth and survival, nutrients and the sun.  Phytoplankton are the primary producers of the ocean the world over, and are eaten by zooplankton.

Fish or even whales then eat zooplankton.

Susan gets to play with a Nutrient Analyzer everyday and it works something like this.  Once the samples are collected from the CTD Rosette, we give them to her.

These samples are then placed on a machine called a

Samples in tubes on rack.


The seawater is then split into four separate channels.  Certain chemicals are mixed with the seawater for each nutrient being tested. 

Chemicals stored for mixing with samples.

Paristaltic pump mixes analytical chemicals
and samples.

The pump draws in the sample and the chemicals to the glass coils.  The samples and chemicals then move through the coils for the purpose of mixing.


One way to check that everything is working properly is to make sure the
bubbles in the coils are equally spaced.


In this picture, you can see the four sets of glass mixing coils with the chemicals and the samples mixing. The chemical reactions that occur in the coils produce a color.  The amount of color that is produced is proportional to the amount of nutrient in the samples.   If you were testing for phosphate, you would take the seawater, mix certain chemicals into it, run it through the machine and see how much blue color is produced.

These data are then compared to a standard for accuracy.  Susan runs that standard before she begins the whole process.  These data are then compiled with other data (like temperature and salinity) to determine where this particular seawater came from in the Arctic Ocean, or from which ocean in the world for that matter.