72
GORDON A. RILE1
at a rate of 7 % on alternate days, and the test was done at the time
when the experiment was terminated after a period of about five weeks.
The following rates were obtained : 15-30 p, 0.82 m/day ; 6-15 p, 0.50 ;
2-6 p, 0-20. These are in general higher than the rates for natural
particles of comparable size, but the difference is not marked.
4. Discussion
Observed sinking rates of different kinds of particles vary by more
than an order of magnitude, and within any particular size category
there is some variation from one experiment to another. Further
variation is introduced by size-frequency differences between one
sample and another, so that there is no simple answer to the question
of what the sinking rate of non-living particulate matter in the sea
may be. The largest particles measured here could sink from the surface to the deep ocean bottom in a little more than two years if they
maintained their integrity that long. The smallest ones would require
fifty years or more.
I n general the largest particles in these counts are volumetrically
the most important constituents. The large volume of individual
particles in the upper size ranges more than compensates for the fact
that they are minor elements numerically. This is illustrated by a
volume computation based upon data obtained in Exp. 1, Table VI.
Particles larger than 60 p are assumed to have a mean volume equivalent to a spherical particle with a diameter of 80 p. The other aggregates are calculated as spheres with mean volumes equivalent to the
size ranges listed. Most of the aggregates appear to be more or less
spherical in the free floating condition, so that this is not a serious
over-simplification. Flakes are calculated as disks with a diameter of
25 p and a thickness of 5 p. The latter is a guess, for they are seldom
oriented in a position that permits measurement of their thickness
with any degree of accuracy.
TABLE VIII. VOLUME COMPUTATIONS BASED UPON DATA FROM E X P . 1
Vol. /particle
Total
103 p 3
Volume
Amorphous aggregates
Number
(X 103 p 3 )
Size range >60 p
6
270
I 6 2 0
30-60
16
63
1008
15-30
38
7.9
300
6-15
58
0.96
56
Misc. particles 2-6
420
0.058
24
Flakes
75
2.4
180
GORDON A. RILE1
at a rate of 7 % on alternate days, and the test was done at the time
when the experiment was terminated after a period of about five weeks.
The following rates were obtained : 15-30 p, 0.82 m/day ; 6-15 p, 0.50 ;
2-6 p, 0-20. These are in general higher than the rates for natural
particles of comparable size, but the difference is not marked.
4. Discussion
Observed sinking rates of different kinds of particles vary by more
than an order of magnitude, and within any particular size category
there is some variation from one experiment to another. Further
variation is introduced by size-frequency differences between one
sample and another, so that there is no simple answer to the question
of what the sinking rate of non-living particulate matter in the sea
may be. The largest particles measured here could sink from the surface to the deep ocean bottom in a little more than two years if they
maintained their integrity that long. The smallest ones would require
fifty years or more.
I n general the largest particles in these counts are volumetrically
the most important constituents. The large volume of individual
particles in the upper size ranges more than compensates for the fact
that they are minor elements numerically. This is illustrated by a
volume computation based upon data obtained in Exp. 1, Table VI.
Particles larger than 60 p are assumed to have a mean volume equivalent to a spherical particle with a diameter of 80 p. The other aggregates are calculated as spheres with mean volumes equivalent to the
size ranges listed. Most of the aggregates appear to be more or less
spherical in the free floating condition, so that this is not a serious
over-simplification. Flakes are calculated as disks with a diameter of
25 p and a thickness of 5 p. The latter is a guess, for they are seldom
oriented in a position that permits measurement of their thickness
with any degree of accuracy.
TABLE VIII. VOLUME COMPUTATIONS BASED UPON DATA FROM E X P . 1
Vol. /particle
Total
103 p 3
Volume
Amorphous aggregates
Number
(X 103 p 3 )
Size range >60 p
6
270
I 6 2 0
30-60
16
63
1008
15-30
38
7.9
300
6-15
58
0.96
56
Misc. particles 2-6
420
0.058
24
Flakes
75
2.4
180