CHAPTER 1 • The Carbonate System in Marine Environments
13
Fig. , .4. The biological pump
-,
r
1
hv
CO2 + H 2 0 - - . CH 2 0 + 0 2
N03' P04' Si02
Thermocline
A sketch of the biological pump is shown in Fig. 1.4. The biological pump is primed
in surface waters by the formation of plant material. This can be represented by the
reaction (Redfield et al. 1963)
The plants need nitrate, phosphate and silicate to grow, as well as some metals such
as Fe and Mn (Millero 1997). When the plants die or are eaten by zooplankton, they
can be removed from the surface and transported to deep waters below the thermocline. Bacteria can oxidize this material back to the starting material
This returns the CO2 back to the waters that will not return to the surface for 500
to 1000 years. Over short periods of time (100 years) the biological pump is thought
to be in a steady state. Over geological periods, it is thought to be the cause of the
changes in CO2 that have occurred in the atmosphere and thus changed the temperature of the earth. It should be pointed out that the composition of phytoplankton given
above (Redfield et al. 1963) has been shown by a number of workers to vary somewhat
on location and species (Takahashi et al. 1985; Anderson and Sarmiento 1994; Steinberg
et al. 1998).
Before we examine the distribution of CO2 in the oceans, we will discuss the chemical concepts which were needed to understand the carbonate system in the oceans.
13
Fig. , .4. The biological pump
-,
r
1
hv
CO2 + H 2 0 - - . CH 2 0 + 0 2
N03' P04' Si02
Thermocline
A sketch of the biological pump is shown in Fig. 1.4. The biological pump is primed
in surface waters by the formation of plant material. This can be represented by the
reaction (Redfield et al. 1963)
The plants need nitrate, phosphate and silicate to grow, as well as some metals such
as Fe and Mn (Millero 1997). When the plants die or are eaten by zooplankton, they
can be removed from the surface and transported to deep waters below the thermocline. Bacteria can oxidize this material back to the starting material
This returns the CO2 back to the waters that will not return to the surface for 500
to 1000 years. Over short periods of time (100 years) the biological pump is thought
to be in a steady state. Over geological periods, it is thought to be the cause of the
changes in CO2 that have occurred in the atmosphere and thus changed the temperature of the earth. It should be pointed out that the composition of phytoplankton given
above (Redfield et al. 1963) has been shown by a number of workers to vary somewhat
on location and species (Takahashi et al. 1985; Anderson and Sarmiento 1994; Steinberg
et al. 1998).
Before we examine the distribution of CO2 in the oceans, we will discuss the chemical concepts which were needed to understand the carbonate system in the oceans.