These methods, instrumentation and/or protocols apply to all data in this dataset:| Methods and protocols used in the collection of this data package |
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| Description: |
Dissolved gas samples were collected at 0.5, 3, 5 and 7 m using the
headspace method. From January to March 2020, water at each discrete depth
was pumped directly into the bottom of a 1-L Nalgene bottle and flushed with
at least three times the volume before being capped with a rubber stopper.
60 mL of ambient air was added while 60 mL of sample water was removed from
the bottle and equilibrated by shaking for 90 seconds. From May 2020
onwards, water was pumped into a closed bottle system, and using syringe,
105mL of water was extracted and 35mL of ambient air was added. The
headspace was then equilibrated for 2 minutes by shaking and 10 mL of
equilibrated gas sample was then removed from the bottle and injected into a
5.9 mL Labco Exetainer vial that had been previously vacuumed. While in the
field, samples were stored in pouches within a survival suit to prevent
extreme temperature change. We analyzed the gas samples for CO2 and CH4 with
a gas chromatograph (GC-2014; Shimadzu Scientific Instruments) equipped with
a methanizer and flame ionization detector. Greenhouse gas concentrations
were calculated according to Henry’s law and corrected by measured ambient
air.
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| | Description: |
Water temperature and dissolved oxygen profiles were taken using a YSI
meter.
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| | Description: |
Inorganic and organic carbon: Samples for inorganic and organic carbon are
collected together with a peristaltic pump and tubing and in-line filtered,
if necessary, (through a 0.40 micron polycarbonate filter) into glass, 24 ml
vials (that are compatible with the carbon analyzer autosampler), and capped
with septa, leaving no head space. The samples are stored refrigerated at 4
degrees Celsius until analysis, which should occur within 2-3 weeks. The
detection limit for inorganic carbon is 0.15 ppm, and the analytical range
for the method is 60 ppm. The detection limit for organic carbon is 0.30 ppm
and the analytical range for the method is 30 ppm.
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