The Role of Fungi in the Production of Biogenic Aerosols

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The Role of Fungi in the Production of Biogenic Aerosols

CO2 Science Magazine - Tempe,AZ*

http://www.co2science.org/scripts/CO2ScienceB2C/articles/V10/N50/B2.j

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Reference

Elbert, W., , P.E., e, M.O. and Poschl, U. 2007.

Contribution of fungi to primary biogenic aerosols in the

atmosphere: wet and dry discharged spores, carbohydrates, and

inorganic ions. Atmospheric Chemistry and Physics 7: 4569-4588.

Background

Citing multiple references as authority for their statements, the

authors note that primary biogenic aerosols (PBA) are " ubiquitous

over land and oceans, " can " influence the Earth's energy budget by

scattering and absorbing radiation, " and can " initiate the formation

of clouds and precipitation as cloud condensation and ice nuclei. "

What was done

Focusing on actively-wet-spore-discharging Ascomycota (AAM) and

actively-wet-spore-discharging Basidiomycota (ABM), Elbert et

al. " address the active (forcible) discharge of fungal spores, which

is accompanied by the emission of aqueous droplets containing

carbohydrates and inorganic ions, ... summarize the information on

the atmospheric abundance of wet and dry discharged fungal spores

that is available from earlier scientific studies made at various

locations around the world, ... and present new measurement results

and budget calculations for aerosol samples from tropical

rainforests in Amazonia. "

What was learned

The four researchers confirmed that AAM and ABM are major sources of

PBA, finding from their own work that " in pristine tropical

rainforest air, fungal spores indeed account for a major fraction of

coarse particulate matter (up to ~45%). " They also calculate that

the emission rate of total fungal spores (~50 Tg yr-1) " is of

similar magnitude as current estimates of the rates of emission and

formation of other types of continental air particulate matter

(primary and secondary organic aerosols). "

What it means

Of particular interest within the context of rising near-surface air

temperatures and atmospheric CO2 concentrations, Elbert et al. write

that " global warming and increasing CO2 concentrations may enhance

the spread of fungi and emission of fungal spores, " citing the works

of Klironomos et al. (1997), Hoye et al. (2007) and Raupach et al.

(2007), while further concluding that " an increase of fungal spores

acting as cloud condensation and ice nuclei may influence the

hydrological cycle and provide either positive or negative feedbacks

to climate change. " We would only add, in this regard, that the

evidence for negative feedbacks of this nature far outweighs the

evidence for positive feedbacks (see the many items archived under

Climate Change (Feedback Factors - Biophysical) in our Subject

Index). This most recent example of a hitherto unappreciated

biological phenomenon thus provides yet another example of how

various life-forms act to maintain earth's near-surface air

temperature within bounds conducive to their own continued existence.

References

Hoye, T.T., Post, E., Meltofte, H., Schmidt, N.M. and Forchhammer,

M.C. 2007. Rapid advancement of spring in the High Arctic. Current

Biology 17: R449-R451.

Klironomos, J.N., Rillig, M.C., , M.F., Zak, D.R., Pregitzer,

K.S. and Kubiske, M.E. 1997. Increased levels of airborne fungal

spores in response to Populus tremuloides grown under elevated

atmospheric CO2. Canadian Journal of Botany 75: 1670-1673.

Raupach, M.R., Marland, G., Ciais, P., Le Quere, C., Canadell, J.G.,

Klepper, G. and Field, C.B. 2007. Global and regional drivers of

accelerating CO2 emissions. Proceedings of the National Academy of

Sciences, USA 104: 10,288-10,293.

Reviewed 12 December 2007