14
GORDON A. RILEY
order of 53-330 pg C/litre, with about two-thirds of the observations
between about 110 and 220 pg.
Riley et al. (1965) took about 20 near surface sampIm in the vicinity
of Bermuda. The average of March-April samples, which probably
represented spring flowering conditions, was 168 pg C/litre, and averages obtained during other seasons ranged from 46 to 111 pg C.
Gordon (1970b) compiled data for some 60 surface layer analyses in
various parts of the N. Atlantic. In the Irminger Sea in April-May
1966, the mean of 11 samples was 44 pg C/litre. In April-May 1967,
a line of stations across the temperate N. Atlantic at approximately
40"N averaged 87 pg. Three cruises were made to Nova Scotia and
Newfoundland shelf and slope waters, and cruise averages ranged from
41 to 176 pgllitre, the largest values being obtained in April 1968.
Five cruises to the Sargasso Sea yielded averages of 29-142pg, and
again the largest values were in April.
A few surface water values have been reported for other oceans.
I n general they fall within the same range and are similarly variable.
One report of considerable interest is that of Szekielda (1967), whose
study of the Somali Current off the east coast of Africa revealed a
series of bands of high and low carbon content running parallel with
the coast. These were believed to be associated with localized upwelling. I n areas where the temperature and salinity structure were
indicative of vertical water movement there was an upward thrusting
of mid-depth water of relatively low carbon content. I n the immediate
surface layer the situation was less clear cut. Theoretically there wilI
be a low particle content in newly upwelled water, but this will give
way to high values as phytoplankton develops in the new water.
Szekielda's data suggest that both phenomena may have been present
in different parts of his profiles. This is clearly a case where one needs
to know something about relative proportions of living and non-living
matter in order to understand the data on total carbon.
Below the immediate surface layer there is almost invariably a
decrease in total particulate carbon. The gradient may be quite sharp
and of limited vertical extent or it may continue more gradually
through most of the main thermocline, but at some depth of the order
of 200-800 m an essentially deep water situation is reached in which
carbon concentrations generally are low and relatively uniform,
although in some cases pronounced increases have been noted in
association with particular water masses. However, there is little or
no systematic decrease with depth.
I n deep water a large proportion of the total organic carbon is
non-living, so that quantitative assessment of that fraction is simpler
GORDON A. RILEY
order of 53-330 pg C/litre, with about two-thirds of the observations
between about 110 and 220 pg.
Riley et al. (1965) took about 20 near surface sampIm in the vicinity
of Bermuda. The average of March-April samples, which probably
represented spring flowering conditions, was 168 pg C/litre, and averages obtained during other seasons ranged from 46 to 111 pg C.
Gordon (1970b) compiled data for some 60 surface layer analyses in
various parts of the N. Atlantic. In the Irminger Sea in April-May
1966, the mean of 11 samples was 44 pg C/litre. In April-May 1967,
a line of stations across the temperate N. Atlantic at approximately
40"N averaged 87 pg. Three cruises were made to Nova Scotia and
Newfoundland shelf and slope waters, and cruise averages ranged from
41 to 176 pgllitre, the largest values being obtained in April 1968.
Five cruises to the Sargasso Sea yielded averages of 29-142pg, and
again the largest values were in April.
A few surface water values have been reported for other oceans.
I n general they fall within the same range and are similarly variable.
One report of considerable interest is that of Szekielda (1967), whose
study of the Somali Current off the east coast of Africa revealed a
series of bands of high and low carbon content running parallel with
the coast. These were believed to be associated with localized upwelling. I n areas where the temperature and salinity structure were
indicative of vertical water movement there was an upward thrusting
of mid-depth water of relatively low carbon content. I n the immediate
surface layer the situation was less clear cut. Theoretically there wilI
be a low particle content in newly upwelled water, but this will give
way to high values as phytoplankton develops in the new water.
Szekielda's data suggest that both phenomena may have been present
in different parts of his profiles. This is clearly a case where one needs
to know something about relative proportions of living and non-living
matter in order to understand the data on total carbon.
Below the immediate surface layer there is almost invariably a
decrease in total particulate carbon. The gradient may be quite sharp
and of limited vertical extent or it may continue more gradually
through most of the main thermocline, but at some depth of the order
of 200-800 m an essentially deep water situation is reached in which
carbon concentrations generally are low and relatively uniform,
although in some cases pronounced increases have been noted in
association with particular water masses. However, there is little or
no systematic decrease with depth.
I n deep water a large proportion of the total organic carbon is
non-living, so that quantitative assessment of that fraction is simpler