『Abstract
The reaction of Ca derived from silicate weathering with CO2 in the world's oceans to form carbonate minerals
is critical step in long-term climate moderation. Ca is delivered
to the oceans primarily via rivers, where it is transported either
as dissolved species or within suspended material. The relative
importance for climate moderation of riverine dissolved Ca vs.
suspended Ca transport stems from the total Ca flux and its climate
dependence. Data in the literature suggest that, within uncertainty,
global riverine dissolved Ca flux is equal to suspended material
Ca flux. To determine how these fluxes depend on temperature and
rainfall, a 40 yr field study was performed on 4 catchments in
northeastern Iceland: Jokulsa(oの頭に¨、aの頭に´)
a(頭に´) Fjollum(oの頭に¨)
at Grimsstadir(iの頭に´), Jokulsa(oの頭に¨、aの頭に´)
a(頭に´) Dal at Bru(uの頭に´)
Jokulsa(oの頭に¨、aの頭に´) a(頭に´)
Dal at Hjardarhagi, and Jokulsa(oの頭に¨、aの頭に´)
i(頭に´) Fljotsdal(oの頭に´)
at Holl(oの頭に´). Suspended material Ca flux
depends more on seasonal and annual temperatures and rainfall
variation than does dissolved Ca flux in all four catchments.
For example, the average difference between the annual maximum
and minimum daily suspended Ca flux for the Jokulsa(oの頭に¨、aの頭に´)
a(頭に´) Dal at Bru(uの頭に´)
is four orders of magnitude, whereas the difference for dissolved
Ca flux is only approximately one order of magnitude. Similarly,
the annual dissolved Ca flux for this river varies by a factor
of 2.6, whereas its annual suspended Ca flux varies by a factor
of 7.1. Because suspended material Ca flux is more dependent on
climate, it provides a stronger negative feedback for stabilizing
Earth's temperature through the greenhouse effect.
Keywords: weathering; dissolved flux; suspended flux; climate
control; atmospheric CO2』
Introduction
Material transport
Ion exchange
Diffusive flux
Suspended material dissolution in the oceans
Results and discussion
Implications
Acknowledgments
References cited