PARTICULATE ORGANIC MATTER IN SEA WATER
29
the main thermocline concentrates particulate food into micro-habitats
which are favourable for filter feeding animals. The evidence is less
clear for the deep ocean. Some thermal structure certainly exists. In
boundaries between water masses of markedly different T-S characteristics, as in the Mediterranean water mass described by Tait and Howe
(1968), considerable vertical variation may occur in the deep ocean.
This is a matter that deserves further attention, for, as will be seen
later, the concentrations of particulate organic matter that have been
observed in routine sampling programmes are minimal for the support
of bathypelagic organisms.
111. CHEMICAL COMPOSITION
There have been excellent and well documented reviews (Provasoli,
1963; Parsons, 1963; Degens, 1968) of the chemical composition of
particulate and dissolved organic matter. The present account will not
repeat the whole story but will merely summarize the salient facts.
Collecting methods have involved centrifugation or accumulation
011 filters of moderate pore size, and the discussion centres on particles
of the order of 0-5 to 1 p or larger. The so-called dissolved fraction
obviously contains smaller particles, including colloids. Little is known
of their composition or even of the quantity of such substances, as
compared with materials in true solution. Fox et al. (1952) examined
the properties of various filters and effected a reasonable separation
of colloids and dissolved materials. The quantity of organic carbon
retained on their ultra-fine filters ranged from 0.16-0.47 mg C/litre in
a series of samples taken at depths of 100-600m off the California
coast. By way of comparison, Holm-Hansen et al. (1966) found that
the particulate carbon removed by ordinary glass fibre filters was 30100 pg C/litre at comparable depths at their station in the California
offing, and the dissolved organic carbon was about 0.45-0.60 mg/litre.
This type of comparison is crude, but the results suggest that a considerable fraction of the so-called dissolved component may actually
be filter-passing particles and colloids. Thus the section that follows
deals with only a fraction of the total particulate matter, and possibly
a minor part of it. However, it is the part that is most immediately
concerned with animals and bacteria.
A. Elementary composition
Parsons and Strickland (1962b) measured carbon and nitrogen in
samples obtained from surface and deep waters at several stations in
the temperate North Pacific (about 19-50°N, 132-145OW). The mean
29
the main thermocline concentrates particulate food into micro-habitats
which are favourable for filter feeding animals. The evidence is less
clear for the deep ocean. Some thermal structure certainly exists. In
boundaries between water masses of markedly different T-S characteristics, as in the Mediterranean water mass described by Tait and Howe
(1968), considerable vertical variation may occur in the deep ocean.
This is a matter that deserves further attention, for, as will be seen
later, the concentrations of particulate organic matter that have been
observed in routine sampling programmes are minimal for the support
of bathypelagic organisms.
111. CHEMICAL COMPOSITION
There have been excellent and well documented reviews (Provasoli,
1963; Parsons, 1963; Degens, 1968) of the chemical composition of
particulate and dissolved organic matter. The present account will not
repeat the whole story but will merely summarize the salient facts.
Collecting methods have involved centrifugation or accumulation
011 filters of moderate pore size, and the discussion centres on particles
of the order of 0-5 to 1 p or larger. The so-called dissolved fraction
obviously contains smaller particles, including colloids. Little is known
of their composition or even of the quantity of such substances, as
compared with materials in true solution. Fox et al. (1952) examined
the properties of various filters and effected a reasonable separation
of colloids and dissolved materials. The quantity of organic carbon
retained on their ultra-fine filters ranged from 0.16-0.47 mg C/litre in
a series of samples taken at depths of 100-600m off the California
coast. By way of comparison, Holm-Hansen et al. (1966) found that
the particulate carbon removed by ordinary glass fibre filters was 30100 pg C/litre at comparable depths at their station in the California
offing, and the dissolved organic carbon was about 0.45-0.60 mg/litre.
This type of comparison is crude, but the results suggest that a considerable fraction of the so-called dissolved component may actually
be filter-passing particles and colloids. Thus the section that follows
deals with only a fraction of the total particulate matter, and possibly
a minor part of it. However, it is the part that is most immediately
concerned with animals and bacteria.
A. Elementary composition
Parsons and Strickland (1962b) measured carbon and nitrogen in
samples obtained from surface and deep waters at several stations in
the temperate North Pacific (about 19-50°N, 132-145OW). The mean