Gschwend%20thesis.pdf

APPENDIX I ANALYTICAL METHODS USED FOR THE DETERMINATION OF
VOLATILE ORGANIC COMPOUNDS IN SEAWATER
Introduction
This appendix describes the methods used for the analysis of volatile
organic compounds in seawater. These stripping methods have been adapted
from others reported in the literature ("Tenax": Zlatkis et aL., 1973;
Novotny et al., 1974; Bellar and Lichtenberg, 1974; Bertsch et al., 1975;
May et al., 1975; "Grob": Grob, 1973; Grob and ZUrcher, 1976). Experiments
performed to evaluate the methods will also be described. Finally, a
brief discussion of the relative merits of these methodological approaches
will be provided.
Sampling
PVC Niskins (5- and 30-liter) with stainless steel or Teflon-coated
springs were used to collect seawater samples. The bottles were flushed
with tapwater and then extensively rinsed at sea before use. Bottles
were stored closed on deck.
A comparison of the volatile organic compounds in surface seawater
samples collected with a 5-liter glass round bottom flask and a PVC Niskin
did not reveal any differences. This was also seen for coastal seawater
samples (Schwarzenbach et al., 1978).
Sampling was always performed with the winds blowing off the sea
and onto the side of the ship with the hydroplatform.
On the Sargasso Sea cruise, water samples were transferred through
the air into round bottom flRsks. For the western Equatorial Atlantic
samples, water was transferred from the Niskin samplers through glass
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