PARTICULATE ORGANIC MATTER IN SEA \VATER
3 7
Chemical oceanographers have paid some attention to a few of the
inorganic constituents, but as yet there is no clear picture of the overall
composition of the inorganic component.
Riley (1959) used the relatively crude technique of measuring dry
weight and difference on ignition of samples of particulate matter
filtered from Long Island Sound waters. The difference on ignition
averaged less than half of the dry weight.
Riley et al. (1965) measured the dry weight of samples of surface
and deep water from the Sargasso Sea and then proceeded to carbon
analysis. Deep water carbon averaged only about 2% of total seston
dry weight.
These collections from relatively unproductive waters probably
represent minimum limits for organic content. Gordon (1970b) used
similar methods on a broader regional scale and concluded that the
organic content, estimated as twice the carbon, averages about onethird of the total dry weight.
Hobson (1967) used a Coulter counter to measure the volume of
particulate matter at his North Pacific stations and then estimated
the weight of particulate matter by assuming a specific gravity of unity.
His results indicated that organic carbon averaged 20% of the total
particulate matter or more in most of his groups of deep water samples.
The method of Krey et al. (1957) and a subsequent series of papers
by Krey and his associates had been mentioned earlier. A good general
summary of their work is given by Krey (1967). Tabular data are given
for a series of stations in the North Atlantic in the general latitudinal
range of 45-55"N. Groups of stations were averaged, and deep water
values for total particulate matter ranged from 25-141 pgllitre. The
protein fraction was 15-45 pgllitre. Krey regarded this latter fraction
as living substance, but biochemical studies cited above would suggest
that some non-living protein also is involved. The results do not give
a clear separation between organic and inorganic materials, but they
suggest that the total organic matter would be at least 30% of the
total and probably more.
Wangersky and Gordon (1965) found that calcium carbonate in
their open ocean collections was about equal to the organic carbon,
with the majority of deep water samples falling between 30 and 80
pg/litre. Chave (1965, 1968) has found that naturally occurring flakes
commonly have crystals of calcite embedded in them. Moreover,
particles of calcium carbonate adsorbed a coating of organic matter
which was sufficiently impermeable to protect them from re-solution
in undersaturated water. Suess (1968) has presented further studies of
the physical chemistry of this process.
3 7
Chemical oceanographers have paid some attention to a few of the
inorganic constituents, but as yet there is no clear picture of the overall
composition of the inorganic component.
Riley (1959) used the relatively crude technique of measuring dry
weight and difference on ignition of samples of particulate matter
filtered from Long Island Sound waters. The difference on ignition
averaged less than half of the dry weight.
Riley et al. (1965) measured the dry weight of samples of surface
and deep water from the Sargasso Sea and then proceeded to carbon
analysis. Deep water carbon averaged only about 2% of total seston
dry weight.
These collections from relatively unproductive waters probably
represent minimum limits for organic content. Gordon (1970b) used
similar methods on a broader regional scale and concluded that the
organic content, estimated as twice the carbon, averages about onethird of the total dry weight.
Hobson (1967) used a Coulter counter to measure the volume of
particulate matter at his North Pacific stations and then estimated
the weight of particulate matter by assuming a specific gravity of unity.
His results indicated that organic carbon averaged 20% of the total
particulate matter or more in most of his groups of deep water samples.
The method of Krey et al. (1957) and a subsequent series of papers
by Krey and his associates had been mentioned earlier. A good general
summary of their work is given by Krey (1967). Tabular data are given
for a series of stations in the North Atlantic in the general latitudinal
range of 45-55"N. Groups of stations were averaged, and deep water
values for total particulate matter ranged from 25-141 pgllitre. The
protein fraction was 15-45 pgllitre. Krey regarded this latter fraction
as living substance, but biochemical studies cited above would suggest
that some non-living protein also is involved. The results do not give
a clear separation between organic and inorganic materials, but they
suggest that the total organic matter would be at least 30% of the
total and probably more.
Wangersky and Gordon (1965) found that calcium carbonate in
their open ocean collections was about equal to the organic carbon,
with the majority of deep water samples falling between 30 and 80
pg/litre. Chave (1965, 1968) has found that naturally occurring flakes
commonly have crystals of calcite embedded in them. Moreover,
particles of calcium carbonate adsorbed a coating of organic matter
which was sufficiently impermeable to protect them from re-solution
in undersaturated water. Suess (1968) has presented further studies of
the physical chemistry of this process.