system of interest can be analyzed through numerical solutions. Moreover, the model outputs of a numerical simulation can be displayed in a biogeochemical field showing
the distribution of species of interest in three dimensions
with temporal variability, which can be used for the diagnostic analysis of biogeochemical cycles and perspective
scenarios of system behavior in the background of climate
change (Sarmiento and Gruber, 2006).
Based on the synthesis of data from the Joint Global
Ocean Flux Study (JGOFS Web-site: http//ijgofs.whoi.
edu/) in the 1990s, it has been indicated that primary production amounts to 0.5 Â 10
15 mol year
À1 of organic carbon for the global continental marginal seas; though
continental margins occupy only 5–10 % of ocean surface, ca. 15 % of total primary production of global ocean
takes place in the coastal oceans (Chen et al., 2003).
Whereas seasonal cycles and interannual to decadal variability in a given latitudinal area are similar in the marginal
seas and the open ocean at surface, it should be noted,
however, that owing to the proximity to the landmass,
the coastal biogeochemical cycles have a stronger character of seasonality as well as interannual variability; the
dimensions of spatial nature differ considerably between
these two realms, revealed, for example, by the change
in biogeochemical budgets (Zhang et al., 2007). For
instance, in the coastal region of the tropical East Pacific
Ocean, the upwelling affects the dissolved iron profiles
in the water column, with elevated Chl-a in the wide shelf
corresponding to high Fe concentrations in surface waters
and depletion of dissolved Fe in the narrow shelf inducing
low Chl-a values (Bruland et al., 2005).
Feedbacks to the earth system and human society
In the coastal as well as the open oceans, there exist close
interactions between biogeochemical cycles and ecosystems from end to end (i.e., from microbial to top predators)
(IMBER, 2005), with profound impact on the human society, such as the water quality (GEOHAB, 2001) and fishery (GLOBEC, 1997).
As the coastal ocean covers a transitional area from an
often more heterotrophic system with large addition of
allochthonous organic matter in coast to a more autotrophic system with dominance of autochthonous organic
matter at open boundary, the nearshore waters are usually
regarded as a CO 2 source to atmosphere, while the offshore waters become the sink of atmospheric CO 2
(Thomas et al., 2004). Hence coastal and marginal seas
can play an important role in the global and oceanic carbon cycles by bridging the land, ocean, and atmospheric
carbon reservoirs.
Humans are part of the global ecosystem, and hence the
future of human society is affected by the interactions
between land, ocean, and atmosphere. Human activities
on land have a profound impact on the coastal biogeochemical cycles and thus on the interactions between biogeochemistry and ecosystem from end to end, which can
change the composition of material fluxes from the coastal
environment to the open ocean and to the atmosphere.
This in turn feeds back on the sustainability of human
society as well as on the marine life (Bauer and Druffel,
1998; Fasham et al., 2001). For instance, coastal eutrophication can induce a change in phytoplankton community
structure (e.g., diatoms relative to dinoflagellates), which
in turn affects the food web structure as well as fish-catch
through transfer of organic matter and chemical energy
between trophic levels. It has been indicated that the emission of some of greenhouse gas species (e.g., CH 4 and
N 2 O) from the coastal ocean accounts for an important
part of global budgets considering its relatively small spatial proportion of world ocean (Bange et al., 2005; Naqvi
et al., 2010). The predicted impacts of climate change in
the future (e.g., global warming and ocean acidification)
have been shown to have irreversible negative impacts
on the marine ecosystems in low (e.g., coral reefs) as well
as in high latitudes (Hoegh-Guldberg et al., 2007; Arrigo
et al., 2008).
Summary and concluding remarks
Coastal biogeochemical cycles exhibit interlinks of different mechanisms that regulate the transfer of chemical elements in the marine ecosystem (e.g., food web) and
encompass rapid and complicated processes that bridge
the material transport between the various compartments
of the Earth system, land, ocean, and atmosphere as well
as human society. The external forcing factors on coastal
biogeochemical cycles can be either natural or anthropogenic, as well as the combination of these two.
Biogeochemistry in the coastal ocean is composed of
cycles of macronutrients and trace elements between
biotic and abiotic compartments driven by formation of
organic matter fueled by solar energy and the metabolisms
(i.e., anabolic and catabolic processes) based on the chemical energy stored in the organisms.
Since the late 1970s, it has been recognized that the
microbial loop can be an important component of biogeochemical cycles in the ocean, which is an integral part of
the entire food web and affects considerably the pathways
of biogeochemical cycles in the coastal ocean. It is known
that coastal biogeochemical cycles have strong feedbacks
to the atmosphere (e.g., emission of greenhouse gases) as
well as the open ocean (e.g., lateral export of particulate
and dissolved organic carbon) through change in material
fluxes.
Acknowledgments
The author expresses gratitude to Profs. Jan Harff and
Bodo von Bodungen for their review comments to
improve the original manuscript of this work.
Bibliography
Arrigo, K. R., van Dijken, G., and Pabi, S., 2008. Impact of a shrinking Arctic ice cover on marine primary production. Geophysical
Research Letters, 35, L19603, doi:10.1029/2008GL035028.
98
COASTAL BIO-GEOCHEMICAL CYCLES
the distribution of species of interest in three dimensions
with temporal variability, which can be used for the diagnostic analysis of biogeochemical cycles and perspective
scenarios of system behavior in the background of climate
change (Sarmiento and Gruber, 2006).
Based on the synthesis of data from the Joint Global
Ocean Flux Study (JGOFS Web-site: http//ijgofs.whoi.
edu/) in the 1990s, it has been indicated that primary production amounts to 0.5 Â 10
15 mol year
À1 of organic carbon for the global continental marginal seas; though
continental margins occupy only 5–10 % of ocean surface, ca. 15 % of total primary production of global ocean
takes place in the coastal oceans (Chen et al., 2003).
Whereas seasonal cycles and interannual to decadal variability in a given latitudinal area are similar in the marginal
seas and the open ocean at surface, it should be noted,
however, that owing to the proximity to the landmass,
the coastal biogeochemical cycles have a stronger character of seasonality as well as interannual variability; the
dimensions of spatial nature differ considerably between
these two realms, revealed, for example, by the change
in biogeochemical budgets (Zhang et al., 2007). For
instance, in the coastal region of the tropical East Pacific
Ocean, the upwelling affects the dissolved iron profiles
in the water column, with elevated Chl-a in the wide shelf
corresponding to high Fe concentrations in surface waters
and depletion of dissolved Fe in the narrow shelf inducing
low Chl-a values (Bruland et al., 2005).
Feedbacks to the earth system and human society
In the coastal as well as the open oceans, there exist close
interactions between biogeochemical cycles and ecosystems from end to end (i.e., from microbial to top predators)
(IMBER, 2005), with profound impact on the human society, such as the water quality (GEOHAB, 2001) and fishery (GLOBEC, 1997).
As the coastal ocean covers a transitional area from an
often more heterotrophic system with large addition of
allochthonous organic matter in coast to a more autotrophic system with dominance of autochthonous organic
matter at open boundary, the nearshore waters are usually
regarded as a CO 2 source to atmosphere, while the offshore waters become the sink of atmospheric CO 2
(Thomas et al., 2004). Hence coastal and marginal seas
can play an important role in the global and oceanic carbon cycles by bridging the land, ocean, and atmospheric
carbon reservoirs.
Humans are part of the global ecosystem, and hence the
future of human society is affected by the interactions
between land, ocean, and atmosphere. Human activities
on land have a profound impact on the coastal biogeochemical cycles and thus on the interactions between biogeochemistry and ecosystem from end to end, which can
change the composition of material fluxes from the coastal
environment to the open ocean and to the atmosphere.
This in turn feeds back on the sustainability of human
society as well as on the marine life (Bauer and Druffel,
1998; Fasham et al., 2001). For instance, coastal eutrophication can induce a change in phytoplankton community
structure (e.g., diatoms relative to dinoflagellates), which
in turn affects the food web structure as well as fish-catch
through transfer of organic matter and chemical energy
between trophic levels. It has been indicated that the emission of some of greenhouse gas species (e.g., CH 4 and
N 2 O) from the coastal ocean accounts for an important
part of global budgets considering its relatively small spatial proportion of world ocean (Bange et al., 2005; Naqvi
et al., 2010). The predicted impacts of climate change in
the future (e.g., global warming and ocean acidification)
have been shown to have irreversible negative impacts
on the marine ecosystems in low (e.g., coral reefs) as well
as in high latitudes (Hoegh-Guldberg et al., 2007; Arrigo
et al., 2008).
Summary and concluding remarks
Coastal biogeochemical cycles exhibit interlinks of different mechanisms that regulate the transfer of chemical elements in the marine ecosystem (e.g., food web) and
encompass rapid and complicated processes that bridge
the material transport between the various compartments
of the Earth system, land, ocean, and atmosphere as well
as human society. The external forcing factors on coastal
biogeochemical cycles can be either natural or anthropogenic, as well as the combination of these two.
Biogeochemistry in the coastal ocean is composed of
cycles of macronutrients and trace elements between
biotic and abiotic compartments driven by formation of
organic matter fueled by solar energy and the metabolisms
(i.e., anabolic and catabolic processes) based on the chemical energy stored in the organisms.
Since the late 1970s, it has been recognized that the
microbial loop can be an important component of biogeochemical cycles in the ocean, which is an integral part of
the entire food web and affects considerably the pathways
of biogeochemical cycles in the coastal ocean. It is known
that coastal biogeochemical cycles have strong feedbacks
to the atmosphere (e.g., emission of greenhouse gases) as
well as the open ocean (e.g., lateral export of particulate
and dissolved organic carbon) through change in material
fluxes.
Acknowledgments
The author expresses gratitude to Profs. Jan Harff and
Bodo von Bodungen for their review comments to
improve the original manuscript of this work.
Bibliography
Arrigo, K. R., van Dijken, G., and Pabi, S., 2008. Impact of a shrinking Arctic ice cover on marine primary production. Geophysical
Research Letters, 35, L19603, doi:10.1029/2008GL035028.
98
COASTAL BIO-GEOCHEMICAL CYCLES