464
The production, transport and preservation of organic matter is part of the global carbon cycle. The
quantification of the entire carbon cycle, including
exchange rates between the atmosphere, the land surface and the ocean, is a complex topic which is not
discussed further in this book.
10.3.2 Primary Production (Overview)
The primary production of organic matter (here described in a broader sense than defined in Sect. 10.4)
is controlled by several factors. Light (for photosynthesis), temperature, and the availability of certain
nutrients all playa large role. On the continents, climate and precipitation are of eminent importance.
The most significant production per unit area on land
is accomplished by tropical rain forests, while desert
regions permit only very limited plant growth. In
aquatic systems, of course, water is not the limiting
factor. Here, primary production is a function of the
amount of light received by the autotrophic community. Sun light also affects the surface temperature of
the water body and thus prornotes life processes.
Many swamps, lakes, estuaries, reefs, and nearshore
zones with inflowing water rich in nutrients have
high primary production rates (Table 10.1). The
growth rate· of primary producers may be limited
when nutrient supply (e.g., nitrate, phosphate, and
so-called micro-nutrients such as vitamins, soluble
organometallic compounds) is insufficient. Therefore, some lakes and low latitude oceanic regions
enable only low growth rates.
Fig. 10.5. aGlobai terrestrial OC fluxes to the ocean,
subdivided into contributions from various climatic
zones which together comprise about 70% of the
entire land surface. Values in parentheses indicate
percentages of global fluxes. (Modified from Ludwig
et al. 1998). b Primary production (iri 10 12 gC/a or
10 6 tC/a) in various regions of the ocean as well as
plant-derived riverine and eolian influxes. Values of
export production to the sea floor are given in percent of primary production. OC burial rates indicate
percentages of total marine burial rate (140-160 x
10 12 gC/a) of which ~50% are of marine, 30% of
terrestrial, and (?) 20% of eolian (thus terrestrial)
Chapter 10 Sedimentation Rates and Organic Matter
Table 10.1. Primary production in various Recent
environments, dry organic matter" in g/m 2 per year or
t!km 2 /a. (Mainly after Huc 1980; for additional data
see Romankevich 1984)
Continents Short grasslands, deserts
Temperate forests
Tropical rain forests
Fresh-water lakes
Salt marshes, mangroves
Marine
Open oceans
Continental shelves
Zones of upwelling
Estuaries
Algal beds
Reefs
50- 20
1300-3200
4000-9000
3000-6000
3300-6000
10- 400
200- 600
400-1200
200-4000
1300-2500
3500-9000
a Conversion factor for organic carbon/organic matter: 0.31
Another term to be considered in mass balances of
organic matter is the "standing crop". This is the biomass present in a given area at a certain time. The
primary net production of plants, for example, can be
estimated by multiplying the average standing crop of
a population by its rate of generation (doubling time).
If the average standing crop doubles once every 2
months, the net production per year will be six times
greater than the standing crop. Thus, the productivity
of a population can be high even though its standing
crop or biomass is small (e.g., in the oceans); similarly, the biomass or standing crop of an ecosystem
can be considerably greater than the annual net productivity (e.g., in forests).
origin. (Based mainly on Hedges and Keil 1995;
Schlünz 1998). c Hydrocarbon index values (from
Rock-Eval pyrolysis and maceral analysis) as a
means of discriminating between marine and terrestrial organic matter. DSDP sampies, vitrinite reflection Ru ::;0.5. (After Stein et al. 1986). d Generalized
relationship between primary net production PP and
new production NP in the present-day oceans.
e Downward C flux, Fe (export production), as a
function of new production NP and water depth z.
(Based on Martin et al. 1987; Berger et al. 1989). See
text for further explanation
The production, transport and preservation of organic matter is part of the global carbon cycle. The
quantification of the entire carbon cycle, including
exchange rates between the atmosphere, the land surface and the ocean, is a complex topic which is not
discussed further in this book.
10.3.2 Primary Production (Overview)
The primary production of organic matter (here described in a broader sense than defined in Sect. 10.4)
is controlled by several factors. Light (for photosynthesis), temperature, and the availability of certain
nutrients all playa large role. On the continents, climate and precipitation are of eminent importance.
The most significant production per unit area on land
is accomplished by tropical rain forests, while desert
regions permit only very limited plant growth. In
aquatic systems, of course, water is not the limiting
factor. Here, primary production is a function of the
amount of light received by the autotrophic community. Sun light also affects the surface temperature of
the water body and thus prornotes life processes.
Many swamps, lakes, estuaries, reefs, and nearshore
zones with inflowing water rich in nutrients have
high primary production rates (Table 10.1). The
growth rate· of primary producers may be limited
when nutrient supply (e.g., nitrate, phosphate, and
so-called micro-nutrients such as vitamins, soluble
organometallic compounds) is insufficient. Therefore, some lakes and low latitude oceanic regions
enable only low growth rates.
Fig. 10.5. aGlobai terrestrial OC fluxes to the ocean,
subdivided into contributions from various climatic
zones which together comprise about 70% of the
entire land surface. Values in parentheses indicate
percentages of global fluxes. (Modified from Ludwig
et al. 1998). b Primary production (iri 10 12 gC/a or
10 6 tC/a) in various regions of the ocean as well as
plant-derived riverine and eolian influxes. Values of
export production to the sea floor are given in percent of primary production. OC burial rates indicate
percentages of total marine burial rate (140-160 x
10 12 gC/a) of which ~50% are of marine, 30% of
terrestrial, and (?) 20% of eolian (thus terrestrial)
Chapter 10 Sedimentation Rates and Organic Matter
Table 10.1. Primary production in various Recent
environments, dry organic matter" in g/m 2 per year or
t!km 2 /a. (Mainly after Huc 1980; for additional data
see Romankevich 1984)
Continents Short grasslands, deserts
Temperate forests
Tropical rain forests
Fresh-water lakes
Salt marshes, mangroves
Marine
Open oceans
Continental shelves
Zones of upwelling
Estuaries
Algal beds
Reefs
50- 20
1300-3200
4000-9000
3000-6000
3300-6000
10- 400
200- 600
400-1200
200-4000
1300-2500
3500-9000
a Conversion factor for organic carbon/organic matter: 0.31
Another term to be considered in mass balances of
organic matter is the "standing crop". This is the biomass present in a given area at a certain time. The
primary net production of plants, for example, can be
estimated by multiplying the average standing crop of
a population by its rate of generation (doubling time).
If the average standing crop doubles once every 2
months, the net production per year will be six times
greater than the standing crop. Thus, the productivity
of a population can be high even though its standing
crop or biomass is small (e.g., in the oceans); similarly, the biomass or standing crop of an ecosystem
can be considerably greater than the annual net productivity (e.g., in forests).
origin. (Based mainly on Hedges and Keil 1995;
Schlünz 1998). c Hydrocarbon index values (from
Rock-Eval pyrolysis and maceral analysis) as a
means of discriminating between marine and terrestrial organic matter. DSDP sampies, vitrinite reflection Ru ::;0.5. (After Stein et al. 1986). d Generalized
relationship between primary net production PP and
new production NP in the present-day oceans.
e Downward C flux, Fe (export production), as a
function of new production NP and water depth z.
(Based on Martin et al. 1987; Berger et al. 1989). See
text for further explanation