PARTICULATE ORGANIC MATTER I N SEA WATER
79
of preparing artificial sea water that is sufficiently pure for the purpose ;
however, basic studies of this type are essential for further progress.
B. Dynamics of production and consumption of non-living
particulate matter in the sea
1. Physical process of movement and dispersal
(a) The surface layer. The fact that particulate matter is concentrated in the immediate surface layer of the sea and in convective
downdrafts is sufficient evidence that production of particles at the
surface is effective ; but we know very little about actual rates of production. Batoosingh et al. (1969) found that when unfiltered sea water
was bubbled, the yield was not significant. This was presumably due
to the same phenomenon that is observed in any other bubbling experiment ; the accumulation of particles inhibits further formation, and
natural sea water contains a large enough concentration of particles to be
inhibiting. One would suppose then tha,t the rate of formation is just
sufficient under ordinary circumstances to replace losses, although
seasonal variation in the non-living fraction indicates some degree of
imbalance between production and removal.
The sea surface presents some of the features of a continuous yield
experiment, and this is primarily responsible for continued production
of flakes. Vertical turbulence in the surface layer tends to counteract
upward flux on bubbles: and convective processes drain off the surface
water and transfer it to a deeper level, in some cases all the way to the
bottom of the mixed layer.
The discussion would profit from a better knowledge of the rate of
convective overturn. As indicated earlier there is some doubt as to
whether Langmuir convection cells are as simple and well organized as
has been indicated in some of the literature, and there is little real
knowledge of either volume transport or depth of penetration of the
downdrafts. However, the mere fact that downdrafts exist, removing
surface materials to a deeper level, is biologically significant, and with
some possible over-simplifications an order of magnitude estimate
should be attempted.
Sutcliffe et al. (1963) measured the sinking speed in convective
downdrafts associated with Langmuir cells by measuring the vertical
displacement of a slightly buoyant disk 20 cm in diameter. They obtained values of the order of 3-6 cmisec. The sinking speed was correlated with wind speed, the higher values being obtained with winds of
about 6 m/sec.
The width of the downdrafts is somewhat variable but commonly
79
of preparing artificial sea water that is sufficiently pure for the purpose ;
however, basic studies of this type are essential for further progress.
B. Dynamics of production and consumption of non-living
particulate matter in the sea
1. Physical process of movement and dispersal
(a) The surface layer. The fact that particulate matter is concentrated in the immediate surface layer of the sea and in convective
downdrafts is sufficient evidence that production of particles at the
surface is effective ; but we know very little about actual rates of production. Batoosingh et al. (1969) found that when unfiltered sea water
was bubbled, the yield was not significant. This was presumably due
to the same phenomenon that is observed in any other bubbling experiment ; the accumulation of particles inhibits further formation, and
natural sea water contains a large enough concentration of particles to be
inhibiting. One would suppose then tha,t the rate of formation is just
sufficient under ordinary circumstances to replace losses, although
seasonal variation in the non-living fraction indicates some degree of
imbalance between production and removal.
The sea surface presents some of the features of a continuous yield
experiment, and this is primarily responsible for continued production
of flakes. Vertical turbulence in the surface layer tends to counteract
upward flux on bubbles: and convective processes drain off the surface
water and transfer it to a deeper level, in some cases all the way to the
bottom of the mixed layer.
The discussion would profit from a better knowledge of the rate of
convective overturn. As indicated earlier there is some doubt as to
whether Langmuir convection cells are as simple and well organized as
has been indicated in some of the literature, and there is little real
knowledge of either volume transport or depth of penetration of the
downdrafts. However, the mere fact that downdrafts exist, removing
surface materials to a deeper level, is biologically significant, and with
some possible over-simplifications an order of magnitude estimate
should be attempted.
Sutcliffe et al. (1963) measured the sinking speed in convective
downdrafts associated with Langmuir cells by measuring the vertical
displacement of a slightly buoyant disk 20 cm in diameter. They obtained values of the order of 3-6 cmisec. The sinking speed was correlated with wind speed, the higher values being obtained with winds of
about 6 m/sec.
The width of the downdrafts is somewhat variable but commonly