Emissions From The Oceans To The AtmosphereDeposition From The Atmosphere To The Oceans

AndThe Interactions Between Them

Tim Jickells

Laboratory for Global Marine and Atmospheric Chemistry

School of Environmental Sciences University of East Anglia

Norwich UK

Outline

CO2 Exchange

Atmospheric Inputs of Nitrogen and Dust to the Oceans

Emissions of Salt and Biogenic Gases from the Ocean

Atmosphere Ocean Feedback Cycles

Global Ocean Colour Composite Image from CZCS scanner

Global Carbon Cycle from IPCCReservoirs in GtC and fluxes in GtC/yr

Nitrate Concentrations In Surface Ocean Waters

Deposition to the Ocean

Current Fixed Nitrogen Inputs to the World Oceans 1012mol yr -1

• Source

• Biological N2 Fixation

• Lightning• Rivers• Atmospheric

• Flux• 5.7• 0.6• 5.4• 3.1-7.9

Organic Nitrogen

• About a third, and perhaps more, of the atmospheric N input is

organic.

• The sources and role of aerosol organic material is very uncertain.

Human Activity has

• had little effect on Biological N2 Fixation and Lightning

• approximately doubled Riverine Inputs

• approximately doubled Inorganic Atmospheric Inputs (NOx and

NH3)

Global Ocean Colour Composite Image from CZCS scanner

Fixed Nitrogen Inputs• Source

• Biological N2 Fixation

• Lightning

• Rivers

• Atmospheric

• Flux

• 5.7

• 0.6

• 5.4

• 3.1-7.9

Atmospheric Inputs of Fixed Nitrogen may be increasing algal growth rates by only a few percent globally because of the large reservoirs of nitrate in deep water but if we consider only “export” production the impact rises to more than 10% in some areas.

Map of the North Sea

Nitrate and ammonium concentrations measured in air at the North Sea coast illustrating the magnitude of pollution events

0

50

100

150

200

250

300

350

16-Aug-99 23-Aug-99 30-Aug-99

aero

sol nit

rate

nm

ol m

-3

coarse nitratefine nitrate

highly polluted southeasterly

winds

0

50

100

150

200

250

300

350

400

450

500

16-Aug-99 23-Aug-99 30-Aug-99 06-Sep-99

aero

sol am

moniu

m n

mol m

-3

coarse ammoniumfine ammonium

unpollutednortherly air

06-Sep-99

Chlorophyll concentrations in the North Sea based on CZCS Images

Composite satellite image of aerosols over the oceans

Nitrate Concentrations In Surface Ocean Waters

Chlorophyll measurements during the SOIREE experiment in the Southern Ocean showing dramatic increases in chlorophyll in the iron fertilised area (open circles) compared to the unfertilised area (dark circles).

Days since beginning of the experiment

Nitrate Concentrations In Surface Ocean Waters

Fixed Nitrogen Inputs

• Source

• Biological N2 Fixation

• Lightning

• Rivers

• Atmospheric

• Flux

• 5.7

• 0.6

• 5.4

• 3.1-7.9

Nitrogen Fixation Requires Iron

Emissions From The Oceans

Schematic illustrating the biogeochemical cycle of iodine including the role of iodine-accumulating macroalgae.

CH2I2

O3O2

CH3I

Precipitation(rain & aerosol)

Reactive IodinePool

h

VOI

I.

I-

IO3- Iodine-Accumulating

Macroalgae

Bacteria /Phytoplankton

IPCC estimates of the magnitude and uncertainties of radiative forcing on the climate system.

Chlorophyll measurements during the SOIREE experiment in the Southern Ocean showing dramatic increases in chlorophyll in the iron fertilised area (open circles) compared to the unfertilised area (dark circles).

Days since beginning of the experiment

Dimethyl Sulphide (DMS) measurements during the SOIREE experiment in the Southern Ocean showing dramatic increases in DMS in the iron fertilised area (open circles) compared to the unfertilised area (dark circles).

Algae

DMSDegradation/Loss

DMS

SO2

Sulphate Aerosol H2SO4 Radiation

Budget

Algae

DMS Degradation/Loss

DMS

SO2

Sulphate AerosolAmmoniun Sulphate Radiation

Budget

NitrateNH3/NH4+

NH3

NH4+

Fe

Algae

DMS Degradation/Loss

DMS

SO2

Sulphate AerosolAmmonium Sulphate Radiation

Budget

NitrateNH3/NH4+

NH3

NH4+

DUSTFeIIIs FeIId+OHSO2 +OH H2SO4

SeaSalt

Cl

Ozone

Conclusions

• Inputs of material from the continents to the Oceans can significantly modify ocean biogeochemical processes.

• Emissions of trace gases and salt from the oceans have a major impact on atmospheric chemistry.

• These emission and deposition processes interact and may play an important role in climate regulation.