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In April 2008 the ANIMATE network Observatories became part of the EuroSITES European Ocean Observatory Network.
Data shown here and subsequent data are available through the EuroSITES website www.eurosites.info
The ANIMATE site will not be updated further.

NAS2 Data Summary
 
Deployment CIS ESTOC PAP
1      Serial No 2399
Instrument lost 		2364
Instrument lost 		2400
Good data
sampling every 8h
2      Serial No 2400
Good data
sampling every 10h 40m 		2398
Invalid standards so
Data invalid 		2404
Data problems
sampling every 8h
3      Serial No Not Deployed 2398 Not deployed due to late
delivery after repair 		2404
Data problems
sampling every 8h
4      Serial No 2400
Still deployed 		2264
Recovered but not yet available 		2398
Data problems
sampling every 8h
5      Serial No   2404
Still deployed 		 
Two standard solutions of Nitrate (NO3)were used for each deployment to regularly calibrate the instrument. The standards were chosen taking in to account the range of levels of nitrate expected at each site.

The 2 standards used were

Site Standards (micromol/l)
CIS 15   25
ESTOC 2   5
PAP 5   15
 

Data Processing

The full calibration document may be downloaded from the ftp site ftp://ftp.noc.soton.ac.uk/pub/animate/, in the animate_documents directory or may be downloaded here (2.6Mb word doc).
Below is a summary of the conversion of sensor output to combined nitrate and nitrite concentration values.

Two measurements are made for all sample points, both standards and samples. These are shown in the data set as two lines; the first is the blank reading and the second is the reading for the reacted sample.

The absorbance is then calculated as ln (blank volts / reacted volts).

The absorbance is then used to calculate the concentration of nitrate as
Absorbance of sample * concentration of standard / Absorbance of standard

 

Example:

Using this fragment from a data file

Type 84=standard, 83=sample,
DateTimeTypeNo.Sample VoltageBattery VoltageComment
12:02:04 12:53:02 84 1 3.689 12.992 blank volts standard 5NO3
12:02.04 12:58:15 84 2 3.212 12.992 reacted volts standard 5NO3
12:02:04 12:59:13 84 3 3.693 12.992 blank volts standard 15NO3
12:02.04 13:04:35 84 4 2.432 12.992 reacted volts standard 15NO3
12:02:04 13:05:02 83 5 3.695 12.992 blank volts SW SAMPLE
12:02.04 13:13:15 83 6 2.798 12.992 reacted volts SW sample

Absorbance standard1: log (3.689/3.212)= 0.0601,conc. put in standard: 5NO3

Absorbance standard2: log (3.693/2.432)= 0.1814,conc. put in standard 15NO3

sample1: ln (3.695/2.798)= 0.1207

[NO3] of samples according to standard 1= 0.1207 * 5/ 0.0601= 10.042

[NO3] of samples according to standard 2= 0.1207 * 15/ 0.1814= 9.9807

The units for nitrate are micromols/l

For each sample two concentrations are calculated, one for each standard. The two concentrations should be similar. Quality control procedures will be developed to mark values as suspect when the two values are not close enough. The absorbance of the standards should stay near constant through the deployment period with only a slight decrease over time.

Data may be found at the ftp site ftp://ftp.noc.soton.ac.uk/pub/animate/, or on the CD, in the animate_data directory

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