Objective   To observe the effect of solar radiation on the survival of the francisella tularensis, B271 phage and B anthracis, which would provide the reference for the prevention and the control of the pollution of biological enviroment.

  Methods   Round stainless stell flakes and thin sand were taken as sample whose surface were polluted.A certain concentration of bacterial suspensions were added to each sample.These samples were put into the box covered with quartz coveres and exposed.Samples were collected by different time and the survival were analyzed.The direct solar radiation and diffuse solar radiation were measured by a pyranometer.

  Results   The direct solar radiation had the most important effect on the survival of three kind of microorganisms.The diffuse solar radiation did secondly.On the same condition, the death rate of francisella trlarensis were 99.65%(direct solar radiation, 20 min)amd 78%(diffuse solar radiation, 20 min).The death rate of B271 phage were 95.45% and 82.70% when the time odirect solar radiation was 2 hours and the time of diffuse solar radiation was 8 hours respectively.The death rate in the controlled group was on more than 1%.The resistance of B anthracis on the stainless stell flake was less than that of in the sur face of thin sand.The former survival was 0 and the later was 11.81% when the time of direct solar radiation was 16 days.Meanwhile, the former was 0 and the later was 34.49% when the time of diffuse solar radiation was 60 days.The former survival was 5.38% and the later was 25.51% in the tenth month in the controlled group.

  Conclusion   The resistance of the three kinds of microorganisms to natural enviroment was B anthracis, B271 phage and francisella tularensis in turn.