18
GOItDON A. RILEY
of Antarctic origin. Thus there were definite indications of water mass
effects in his profiles.
2 . Discussion of results
(a) Methods. The various investigators who contributed to present
knowledge about the distribution of particulate organic carbon have
used a variety of methods in almost every phase of the work. Thus
the question naturally arises as to whether the results really are comparable. This problem has largely been dealt with in the methods
section in connection with the intercomparisons made by Gordon
(1969) of various pore sizes of filters and of plastic versus glass Sampling bottles. I n no cases were there significant differences. His
carbon analyses were carried out in part on an F. & M. Model 185
CHN analyser and partly in an apparatus assembled by P. J. Wangersky,
which involved dry combustion and determination of the CO, in a
Beckman infra-red analyser. He also arranged with D. IV. Menzel for
an intercomparison of determinations by the method of Menzel and
Vaccaro (1964). Again no significant differences resulted from differences in methods.
This removes much of the uncertainty from regional comparisons
of the type that is intended here. To be sure, great care must be
exercised in maintaining cleanliness in sampling bottles and filtration
techniques, and corrections for the carbon content of filters are always
troublesome. Some investigations, and particularly the early ones, may
be in error due to failure to recognize all of these problems. However,
there are no indications of gross error that warrant discarding any of
the early data.
But there is no simple solution to the problem of analysing particulate organic matter. Ranging in size from macroscopic particles t o
colloids, it cannot be sampled quantitatively by any filter now in use,
nor is there any present filter that effects a precise size fractionation.
Further study of size spectra is needed, but for routine examination of
regional variations the prime requirement is for general agreement on
a standard method, and as is usual in such cases, some compromise is
necessary. A fairly large quantity of water must be filtered in order
to minimize errors in blank determinations, and this is inconsistent
with the use of filters with very fine pores, which would be desirable
in order to retain small particles. I n practice, silver filters of 0.8 or
1.2 p pore size appear to be a good compromise.
Menzel (1967) assumed that dissolved organic matter is adsorbed on
filters and attempted to correct this. Subsequent papers by Menzel and
Ryther (1968a and b) did not provide details as to whether similar
GOItDON A. RILEY
of Antarctic origin. Thus there were definite indications of water mass
effects in his profiles.
2 . Discussion of results
(a) Methods. The various investigators who contributed to present
knowledge about the distribution of particulate organic carbon have
used a variety of methods in almost every phase of the work. Thus
the question naturally arises as to whether the results really are comparable. This problem has largely been dealt with in the methods
section in connection with the intercomparisons made by Gordon
(1969) of various pore sizes of filters and of plastic versus glass Sampling bottles. I n no cases were there significant differences. His
carbon analyses were carried out in part on an F. & M. Model 185
CHN analyser and partly in an apparatus assembled by P. J. Wangersky,
which involved dry combustion and determination of the CO, in a
Beckman infra-red analyser. He also arranged with D. IV. Menzel for
an intercomparison of determinations by the method of Menzel and
Vaccaro (1964). Again no significant differences resulted from differences in methods.
This removes much of the uncertainty from regional comparisons
of the type that is intended here. To be sure, great care must be
exercised in maintaining cleanliness in sampling bottles and filtration
techniques, and corrections for the carbon content of filters are always
troublesome. Some investigations, and particularly the early ones, may
be in error due to failure to recognize all of these problems. However,
there are no indications of gross error that warrant discarding any of
the early data.
But there is no simple solution to the problem of analysing particulate organic matter. Ranging in size from macroscopic particles t o
colloids, it cannot be sampled quantitatively by any filter now in use,
nor is there any present filter that effects a precise size fractionation.
Further study of size spectra is needed, but for routine examination of
regional variations the prime requirement is for general agreement on
a standard method, and as is usual in such cases, some compromise is
necessary. A fairly large quantity of water must be filtered in order
to minimize errors in blank determinations, and this is inconsistent
with the use of filters with very fine pores, which would be desirable
in order to retain small particles. I n practice, silver filters of 0.8 or
1.2 p pore size appear to be a good compromise.
Menzel (1967) assumed that dissolved organic matter is adsorbed on
filters and attempted to correct this. Subsequent papers by Menzel and
Ryther (1968a and b) did not provide details as to whether similar