The Study Of Distribution Characteristics Of Negative Air Ions And Radon And Its Correlations With Environmental Factors

Naturally, the decay of 222 Rn results in the release of rays, such as α、β and γ. As the ionization energy of these rays is high, especially the α-ray, so they can promote the surrounding air ionized to produce air ions, including the negative and positive ions. On one hand, the higher of the concentration of negative air ions, the greater of the air cleanliness. On the other hand, the increasing of radon concentration can accelerate the occurrence of body diseases, especially lung cancer. It can be seen that air ions and radon are two atmospheric trace constituents which have opposite effects on human health. Therefore, the domestic and foreign scholars focus on the relationship between them gradually.In this study, the concentrations of negative air ions and 222 Rn were measured at three monitoring points on Chang`an University with DLY-2G air ion monitor and Radon Detector-RAD7,respectively. Simultaneously,the environmental factors, such as temperature, relative humidity and average wind speed were also measured. The temporal-spatial distribution characteristics of negative air ions and 222 Rn were studied, and the inner reasons were further analyzed. Then the relationships between negative air ions, 222 Rn and environmental factors were performed a deeper analysis. Finally, a preliminary exploration of the relationship between negative air ion and 222 Rn was conducted in this paper.The results show that the temporal distributions of negative air ions and 222 Rn concentration are obviously heterogeneity. The daily variation of negative air ions presents a double-peak phenomenon clearly, that is, the maximum values are 530 and 319 cm-3, at 04:30 am and 14:30 pm, whereas the minimum are 357 and 337 cm-3, at 08:30 am and 17:30 pm, respectively. As for the diurnal variation of 222 Rn, it lags behind the change of negative air ions and is similar to the tendency of sine curve. The maximum with obvious peak is 18.7Bq/m3 at 06:30 am, and the minimum is 11.1Bq/m3 at 16:30 pm, where the curve is more gentle. Significant seasonal variation of negative air ions is observed with highest level in summer, followed by in autumn and spring, and lowest in winter, but the variation of 222 Rn is completely opposite with that of negative air ions, in other words, the concentration of 222 Rn in order is winter, spring, autumn and summer.Secondly, the concentrations of negative air ions and 222 Rn in play ground(PG) are both higher than that of in Luoma square(LMS) in spatial distribution. There is no significant difference in the negative air ions concentration between the two monitoring points(p=0.092>0.05), but the significant difference is found in the concentration of 222Rn(p=0.00<0.05). Then, the negative air ions and 222 Rn concentrations in roof of school(ROS) and Luoma square(LMS) were used to study the variations of concentrations with height. The results show that the negative air ions concentration increases with the increase of height, but the difference is not significant(p=0.112>0.05). Instead, the height is lower, the concentration of 222 Rn is higher, and the difference is significant(p=0.023<0.05).Finally, the relationships between the negative air ions and 222 Rn concentrations and environmental factors were studied. It is obtained that there is a positive correlation between the concentration of negative air ions and temperature and relative humidity, while the average wind speed is negatively correlated with negative air ions concentration. Besides, the influence of relative humidity on negative air ions concentration is strongest, followed by the temperature, the average wind speed is the weakest. As for radon in the atmosphere, it is negatively correlated with temperature and average wind speed, but the positively correlated with relative humidity. In order of effect degree, it goes: temperature, average wind speed and relative humidity.