Biogeochemical Impacts of Dust on the Global Carbon Cycle - Mineral Dust: A Key Player in the Earth System - page 353

Chapter 14
Biogeochemical Impacts of Dust on the Global
Carbon Cycle
Tim Jickells, Philip Boyd, and Keith A. Hunter
Abstract Dust supply can directly affect primary production in terrestrial and
marine ecosystems and thereby affect local and planetary biogeochemistry. The
impact on land appears to be primarily in terms of dust providing a supply of
phosphorus to phosphorus-limited ecosystems, thereby increasing primary produc-
tion directly, and to also relieve phosphorus limitation of nitrogen fixation, which
then also allows increased primary production. The impact of dust as a phosphorus
source seems to have the biggest impacts in terrestrial tropical systems, reflecting
both the global dust supply pattern as well as the fundamental biogeochemistry of
soil development and biogeochemical cycling in these environments. Dust supply
can also in some environments, particularly Caribbean islands, provide a significant
part of the soil itself. In marine ecosystems, the most important role of dust appears
to be a source of iron. This dust-derived iron supply acts to directly increase
primary production in surface waters of high-nitrate low-chlorophyll regions where
primary production is iron limited. These areas are predominantly at high latitudes
and include the vast Southern Ocean. The dust-derived iron supply also plays an
important role in relieving iron limitation of nitrogen fixation in tropical surface
ocean waters and thereby increases primary production in these areas.