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SOP6 – Water Quality Analysis
43
After all flasks are filled, use a 200 µl pipette to feed each sample with 175 µl each of the
following nutrients:
a.
Sodium nitrate (NaNO
3
)
b.
Sodium dihydrogen phosphate (NaH
2
PO
4
- H
2
O)
c.
Sodium metasilicate (Na
2
SiO
3
– H
2
O)
See section 7.4.5 for nutrient composition.
Immediately recover the flask with the paper/foil cap. Use a new pipette tip for each different
nutrient to reduce contamination. Replace the tip if it touches the flask or the sample water.
Note the general time of feeding. When all of the flasks are fed, remove the foil and use a rubber
band to secure the blue Bio-Shield paper. Swirl each flask gently but thoroughly to mix nutrients
in with the sample. Time the grow-lights to roughly match day and night hours (check sunrise
and sunset).
7.4.3. During Regrowth Experiments
Swirl each flask a few times each day (do not splash up on the sides), noting the time. Also at
those times, switch their positions under the light array.
7.4.4. End of Regrowth
– after 5.5 – 6 days
Filter for chlorophyll
Set up filtering rig, label, wear gloves, etc. Swirl the flask well, and pour all 350 mls from each
flask into the filtering cup using the correct filter rig (one is labeled “T” and one is labeled “C”)
Do not have to use a to-deliver graduated cylinder. Rinse the sides and bottom of the flask with
0.2 µm filtered, autoclaved seawater,
NOT distilled water.
Note filter time and amount (always 350 mls). Place each filter into its own labeled foil packet
and freeze in a labeled 1-qt. freezer bag and place in the freezer. Turn off both power strip
switches. As soon as possible, take frozen filtered samples (in a small cooler with ice pack) and
original data sheet(s) to NASL. A MERC and NASL employee must co-sign each one. Make a
darkened copy of the data sheet. Leave the original with NASL and file the copy in data
manager’s office.
7.4.5. Regrowth Stock Solution
Based on Guillard’s f/2 enrichment (Guillard 1975)
Five working stock solutions are prepared:
1.
NaNO
3
2.
NaH
2
PO
4
* H
2
O
3.
Na
2
SiO
3
* 9H
2
O – required for diatoms only
4.
Trace metal
5.
Vitamins