Background on the Ocean Carbon Cycle and Sequestration

• Ocean Fertilization and Direct CO₂ Injection
• Oceanography and Ocean Carbon Sequestration
• Some Basic Ocean Carbon Cycle Facts

Ocean Fertilization and Direct CO2 Injection
	Ocean Fertilization is a sequestration strategy aimed at enhancing the transport of carbon through the base of the euphotic zone into the deep sea. A possible useful by product is increased fish yields. Research is required to avoid bad side effects such as toxic blooms. Direct Injection of CO2 into the mid-water column seeks to short circuit the natural delivery of CO2 into the deep sea and minimize environmental impacts by avoiding the biologically rich upper 1000 m.
Oceanography and Ocean Carbon Sequestration
	Oceanographic features relevant to carbon sequestration and some basic research questions: Does enhancement of natural cycle by fertilization lead to desirable changes in the efficiency of carbon export to the deep ocean? Does direct CO2 injection succeed in sequestering carbon in deep waters so that it remains isolated from the atmosphere for hundreds of years? Are either of these options environmentally acceptable?
Some Basic Ocean Carbon Cycle Facts
Although plant biomass in the ocean is less than 0.05% of that on land,ocean biota cycle almost the same amount of carbon per year.
Where the Carbon is: in major reservoirs on Earth Reservoir Quantity 1 Pg C=1015g C Reservoir component breakdown Total Atmosphere CO2 720 720 Oceans Total inorganic Total organic 37,400 1,000 38,400 Lithosphere Carbonates Kerogen 60,000,000 15,000,000 75,000,000 Terrestrial Biosphere Living biomass Other 600 to 1,000 1,200 ~ 2,000 Aquatic Biosphere marine organisms 1 to 2 1 to 2 Fossil Fuels (from conventional sources) Coal Oil Gas Other (peat) 3,510 230 140 250 4,130	Annual Net Primary Productivity of major biosphere units (in Pg C/y) (adapted from Falkowski et al., 1998) Biogeographic Unit NPP Terrestrial Unit NPP Mesotrophic 27.4 Tropical rain forests 17.8 Oligotrophic >11.0 Savannas 16.8 Eutrophic 9.1 Cultivation 8.0 Macrophytes 1.0 Broadleaf and needleleaf forests 3.1     Needleleaf evergreen forests 3.1     Perrennial grasslands 2.4     1.5     Needleleaf deciduous forests 1.4     Broadleaf shrubs with bare soil 1.0     Tundra 0.8     Desert 0.5 TOTAL OCEAN 48.5 TOTAL LAND 56.4