IPCC Fourth Assessment Report: Climate Change 2007 Climate
Change 2007: Working Group I: The Physical Science Basis Carbon
Cycle Feedbacks Induced by Nutrient Cycling and Land Ocean
Coupling  Rivers deliver carbon (DIC, DOC) and nutrients to the
ocean. Rising CO2 levels in the atmosphere and land use may lead
to increased chemical and physical weathering, resulting in
increased carbon and alkalinity loads in rivers (Clair et al.,
1999; Hejzlar et al., 2003; Raymond and Cole, 2003; Freeman et
al., 2004). Depending on the lithology and soil composition of
the catchment areas, increased levels of alkalinity, DIC or DOC
can lead to local positive or negative feedbacks. Mobilisation
of silicate carbonates from soils and transfer to the ocean
would lead to a negative feedback to atmospheric CO2 on long
time scales (Dupre et al., 2003). Variations in nutrient supply
can lead to species shifts and to deviations from the large-
scale average Redfield ratios mainly in coastal waters, but also
in the open ocean (Pahlow a