~ ) Pergamon J. Aerosol Sci., Vol. 28, Suppl. 1, pp. S3-$4, 1997 ©1997 Elsevier Science Ltd. All rights reserved

Printed in Great Britain PH:S0021-8502(97)00049-9 0021-8502/97 s17.00+o.oo

A CONTRIBUTION OF PRIMARY BIOLOGICAL AEROSOL PARTICLES AS INSOLUBLE COMPONENT TO THE

ATMOSPHERIC AEROSOL OVER THE SOUTH ATLANTIC OCEAN

Sabine Matthias-Maser, Martina KrOner, Jut ta Brinkmann, Wilhelm Schneider Institute of Physics of the Atmosphere, University Mainz

Becherweg 21, 55099 Mainz, Germany

K e y w o r d s

Primary biological aerosol particles, biologically contaminated particles, insoluble particles, size distribution.

I n t r o d u c t i o n

The atmospheric aerosol consists of different gases, ice nuclei, waterdroplets and of the aerosol particles. These include mineral dust, sea salt, vulcanic dust, soot, particles which are produced by chemical and physical reactions of trace gases, and the primary biological aerosol particles. Primary biological aerosol particles (PBAP), i.e. pollen, spores, plant debris, epithelial cells, bacteria, algae, protozoa and viruses, are an ubiquitous component of the atmospheric aerosol, they are present in all size ranges and they are thought to be insoluble. Besides their effects on air hygiene and health biological particles play an important role in cloud physics, for example some bacteria are able to accumulate water and act as ice nuclei.

Over half of the earth is covered with water so the marine atmosphere supplies an impor- tant contribution to the total atmospheric aerosol and their influence on atmospheric processes. Besides crust and cryosphere, gas to particles conversion and clouds, the ocean and fresh water bodies belong to the 4 major sources of aerosol particles (Jaenicke and Matthias-Maser, 1992), they contribute with 1000-2000 Tg/year. Marine atmosphere is characterized by particles which originate from the ocean and by those which reached the air by advection from the continent. The major component of the marine aerosol particles is the sea salt. But the ocean is also an important source for microorganisms. The bubble - burst mechanism produces both sea salt as well as biological particles The microbes are collected in a microlayer around the rising bubble and are ejected with the jet-drops into the air (Blanchard 1972). This mechanism also produces seasalt particles which are biologically contaminated. The following article is occupied with the determination of the size distribution of the marine aerosol particles with special respect on the biological particles.

M e t h o d s

For sampling aerosols a two-stage-slit-impactor and a wing-impactor are used. The coarse particles are sampled on coloured glycerol jelly (Matthias, 1987). The biological particles get stained and can be distinguished in opposite to the non-dyed particles using a light microscope. In this size range some particles can be detected, which have stained areas, they are biological contaminated. The small particles are examined in a scanning-electron-microscope (SEM) equipped with an energy dispersive x-ray spectrometer (EDX) after sampling on graphitic foils (Matthias-Maser, 1992).

$3

$4 Abstracts of the 1997 European Aerosol Conference

Three criteria were used to characterize the particles: the morphology, the elemental composition and the behaviour during EDX. The literature (McCrone and Delly, 1973) and own experiments show, that the biological particles have special morphology (spheres, rods, characteristic forms) together with a special elemental composition (P, S, K, Ca, sometimes Si, Cl) and some of them change their form during EDX (shrinking). Based on above mentioned criteria a scheme was developed dividing the atmospheric aerosol in 6 groups each of them represents biological or non- biological particles.

Results

The data were won on three cruises with the gernm~ Research vessel "METEOR" crossing the South Atlantic Ocean at 15 ° northern latitude, around the equator, at 10 ° and at 30 ° southern latitude. As a first result, the biological percentage decreases within a distance of 200-300 seamiles from the continent. Looking at the individual size distribution itself we found out that the vari- ation of the biological particles with r > 0.2/~m is about one order of magnitude whereas the particles larger 2pro alternate within 3 orders of magnitude. Here the single components vary be- tween alternaria spores, needles (perhaps cilia of some microorganisms), clusters of microbes and sometimes some kinds of pollen (we found coniferous pollen whose air bags are a good support for long range transport).

Excluding the continentally influenced measurements mean concentrations for number and volume for pure marine atmosphere were calculated. The measurements showed that the biological particles come to a percentage of 17% in number and 10% in volume concentration for particles with radius larger than 0.2/~m. In comparison to that the biological percentage in an urban/rural influenced region was 24% in number and 22% in volume (Matthias-Maser, 1996).

Another kind of particles became obvious in marine atmosphere, the biologically contaminated particles, i.e. particles which consists partly (approximately untill a third) of biological matter. Their concentration in the evaluated size class (r> 2/~m) is higher than the concentration of the pure biological ones.

As a result the measurements show that the marine aerosol particles consists to at least 17% in number and 10% in volume of unsoluble (biological) particles and this value does not contain the biologically contaminated particles, so the insoluble mass of the giant particles could be even a third or a forth higher.

R e f e r e n c e s

Blanchard D.C., Syzdek L.D.(1972) J.o~ Geoph~s.P~s. Vol. 77, No.27, p.5087-5099. Jaenicke R., Matthias-Maser S. (1992) in: Schwartz S.E., Slinn W.G.N. (eds) Precipitation Scavenging and Atmosphere-Suffa~ Exchange, Vol.3. Washington, 1992. Matthias, S. (1987) Masters Thesis University of Malnz. Matthia~Maser S. (1992) Ph.D. Thesis University of Mainz. Matthias-Maser S., (1996) submitted to Harrison R.M., Van Grieken R.E. (eds) Environmental Particles Vol IV, Wiley & Sons. McCrone W., Delly H.A. (1973) Particle Atlas, Edition two, Ann Arbor Science Publisher, Ann Arbor Michigan.