Environmental Engineering Reference
In-Depth Information
carbon (DIC) sequestration through photosyn-
thetic processes. Carbon dioxide required for
photosynthesis diffuses through the cell mem-
brane of most phytoplankton species, while both
carbon dioxide and HCO
−
can be incorporated
through adenosine triphosphate (ATP)-dependent
mechanisms called carbon dioxide-concentrating
mechanisms (CCMs) (Raven
1997
). It is expec-
ted that long-term elevation of carbon dioxide
would downregulate the activity of CCMs,
increasing the energy available for other cellular
processes and resulting in increased carbon
from the database that the distribution of these
two groups of phytoplankton is controlled by the
rate of nutrient input to the system. If nutrients
enter the upper oceans (through continental run-
off), diatoms dominate in the system, but
if
nutrients are supplied slowly,
the coccolitho-
phorids are selected. Tasio
ect
the view that the relative distribution of diatoms
and coccolithophorids is strongly dependent on
the mechanisms that supply nutrients into the
upper mixed layer of the ocean. The project
suggests that this mechanistic connection is the
major factor responsible for the succession and
domain shifts of these two phytoplankton func-
tional groups in the ocean.
Laboratory analysis also con
'
s results thus re
fl
x-
ation and growth rates (Raven
1991
). However,
the effect of elevated carbon dioxide on growth
and photosynthesis differs among studies, and
more work is still needed to understand phyto-
plankton response to a rise in carbon dioxide
concentrations (Riebesell et al.
1993
; Hein and
Sand-Jensen
1997
; Tortell et al.
2000
). A proper
evaluation of future carbon dioxide concentra-
tions depends not only on estimates of the carbon
emitted from anthropogenic activities and stored
in the atmosphere, but also on our knowledge of
the physical and biological processes affecting
ocean
rmed that the
distribution of phytoplankton is correlated with
the injection of nutrients into the upper ocean. In
nature, high latitude, temperate and upwelling
systems receive substantial amounts of nutrients
from deep-waters via wind-driven vertical mix-
ing, leading to the dominancy of diatoms. In
contrast, phytoplankton inhabiting low-latitude
environments largely rely on slow nutrient dif-
fusion from deep-waters to sustain their standing
stocks, and coccolithophorids dominate. The
discussion thus throws light on the standing
stock and taxonomic diversity of phytoplankton
that mainly govern the magnitude and direction
of carbon dioxide exchange in the ocean
atmosphere feedback. Recent results have
suggested that variation among experiments can
be related to both interspeci
-
c differences in the
mechanisms responsible for carbon incorporation
and the dependence of DIC uptake on other
factors, such as nutrients and light availability
(Leonardos and Richard
2005
). The salinity level
of the aquatic phase also regulates the phyto-
plankton volume in marine and estuarine envi-
ronment (Mitra et al.
2012
; Mitra
2013
), which
subsequently in
atmo-
sphere matrix. The role of salinity is also vital as
this variable not only in
-
fl
uences the phyto-
plankton diversity, but also controls the cell
volume and subsequently the carbon storage
capacity (Mitra et al.
2012
).
Carbon
fl
uences the carbon content in the
phytoplankton.
The Tasio project
xation by photoautotrophic algae has
the potential to diminish the release of carbon
dioxide into the atmosphere and help alleviate
the trend towards global warming. Primary pro-
ducers of coastal and marine ecosystems such as
phytoplankton, seaweed and seagrass are excel-
lent carbon-sequestering agents than their ter-
restrial counterparts (Zou
2005
). More than
36.5 Gt of carbon dioxide is captured each year
by planktonic algae through photosynthesis in
the oceans (Gonzalez et al.
2008
). Zooplankton
dynamics are a major controlling factor in the
sedimentation of particulate carbon in open
o et al.
2008
) analysed phytoplankton community com-
position across four latitudinal transects in the
Atlantic Ocean to look at the processes control-
ling the biogeographical distributions of phyto-
plankton and their role in the carbon cycle. The
project team members applied a diagnostic
analysis to a coupled atmosphere
'
s research (Cerme
ñ
ocean general
circulation model to make projections about the
response of diatoms and coccolithophorids in the
next century and their potential impact on the
sequestration of atmospheric carbon. They stated
-
