PART X — ENVIRONMENTAL CONTAMINANTS 



in some instances transmitting plant 

 viruses they brought with them. The 

 U.S. Department of Agriculture has 

 worked out many of the disease- 

 transmission possibilities, but we do 

 not yet have enough coordinated ob- 

 servations to be able to assess the 

 significance of such insect transport. 



In the tropics, vectors such as the 

 tsetse fly generally show patterns of 

 narrower endemism, and this should 

 be studied against the possibility of 

 human activity inadvertently creating 

 favorable conditions for a dangerous 

 vector in a new area. There is clearly 

 need for assessment of existing 

 knowledge in this area and an effort 

 to determine efficient courses for 

 further action. 



"Aerial Plankton" in Relation to 

 Genecology and Phytogeography 



A neglected but obvious functional 

 aspect of the aerial transport of pol- 

 len and spores, and of all other par- 

 ticles that are propagules, is that this 

 process represents transfer of genetic 

 material from one geographic area to 

 another and, in the event of germi- 

 nation on the new site, injection of 

 more or less different genetic material 

 into a population. If we are to under- 

 stand the ecological genetics, or "gen- 

 ecology," of populations, quantitative 

 as well as qualitative aspects of at- 

 mospheric dispersal of viable prop- 

 agules and pollen must be studied. 

 Applications having considerable eco- 

 nomic importance will follow closely 

 in such activities as breeding of hy- 

 brid crop plants and forest trees. 



In the course of observing aerial 

 transport of viable propagules, we 

 should be on the lookout for those 

 that would have come from a distant 

 source. This evidence would help to 

 resolve many old arguments for or 

 against long-distance transport as ex- 

 planations of wide disjunctions of 

 range. 



Wind transport of humus and 

 other organic material out of one eco- 



system unit and into another has 

 become a matter of concern to ecol- 

 ogists studying productivity in detail. 

 They find this export and import of 

 materials and energy attaining sig- 

 nificance in the production budgets 

 of climates that are dry and windy, 

 at least for seasonal periods. Aero- 

 biologists are currently trying to help 

 the ecologists of the IBP Grassland 

 Biome Project in Colorado to obtain 

 reliable measurements of amounts of 

 material in transit at given times and 

 accumulating on different sites over 

 specific time intervals. 



Historical Studies — "Microfossil" 

 pollen grains, spores, diatoms, and 

 other small and identifiable organic 

 particles in sediment have been used 

 for over half a century to obtain 

 stratigraphic correlations and paleo- 

 ecological reconstructions. The most 

 detailed and refined uses are made 

 of late Quaternary microfossils be- 

 cause they are so nearly like the 

 living forms of which we have first- 

 hand knowledge. Several aerobiolo- 

 gists are endeavoring to identify 

 strategically located sedimentation 

 sites and airborne biological forms 

 accumulating in them today in order 

 that the older sediments might, in 

 effect, extend the baseline for envi- 

 ronmental monitoring back in time 

 some hundreds or thousands of years. 

 Opportunities may present them- 

 selves for linking in time the changes 

 indicated by airborne particles with 

 changes indicated by aquatic-system 

 elements. Some inland lakes are 

 known to have sediments that are 

 annually banded, so that precise dates 

 can be obtained for the record of the 

 past. One such lake in Minnesota 

 has nearly 10,000 annual bands in 

 its sediments. 



Prospects for Aerobiology 



In his book Microbiology of the 

 Atmosphere, Gregory stated: 



Our knowledge of the terrestrial 

 air-spora is fragmentary in the 



extreme. The air has never been 

 systematically explored simultane- 

 ously in different parts of the 

 world by comparable methods. 

 There is a heap of accumulated 

 data. . . . Here and there are in- 

 triguing suggestions of phenomena; 

 but many of the data are unin- 

 terpretable, and we need a fresh 

 study of aerobiology as part of a 

 vast terrestrial process. 



The IBP Aerobiology Program is ini- 

 tiating just such efforts as a transient, 

 first step. It has sponsored, jointly 

 with the Environmental Protection 

 Agency, a conference entitled "Aero- 

 biology Objectives in Atmospheric 

 Monitoring," at which meteorologists 

 and aerobiologists drew up the first 

 lists of priorities for information ac- 

 quisition and assessed the practicali- 

 ties of sampling and data processing. 

 These people will look ahead to inte- 

 grating these activities into the pro- 

 posed GNEM (Global Network for 

 Environmental Monitoring). The 

 prospects are that support for world- 

 wide environmental monitoring, in 

 aerobiology at least, will be well re- 

 paid by the benefits realized. 



The Secretary-General of the 

 United Nations is calling for an inter- 

 national body that will supervise 

 sentinel and warning stations for 

 detrimental changes in environments 

 and biota all over the earth, and the 

 plans for the GNEM constitute the 

 preliminary blueprint. ICSU (Inter- 

 national Council of Scientific Unions) 

 and its member organizations — IUBS 

 (International Union of Biological 

 Sciences), in particular — are ready- 

 ing a larger scheme, called the "Man 

 and the Biosphere" program, designed 

 to interpret the changing conditions 

 for man and the organisms sharing 

 the earth and supporting him, and to 

 plan for improvement of conditions 

 for human life in the future. 



For at least the decade of the 

 1970's, organizations serving aerobio- 

 logical needs must be kept adaptable 

 and responsive to widely different 



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