| With the develop of the city, there are more and more buildings, the range of the human activities gradually rise to the near surface layer. It’s increasingly important to research variation of the surface nitrogen oxides and sulfur dioxide concentrations. Understanding the change law of nitrogen oxides and sulfur dioxide has scientific significance. Study on the nitrogen oxides and sulfur dioxide in urban area has practical significance to control nitrogen oxides and sulfur dioxide pollutions.In April and May 2014, nitrogen oxides and sulfur dioxide concentrations and meteorological factors in a range of 70 m of the eastern suburbs of Xi’an were observed in six days and nights.(1) The concentration of nitrogen oxides circadian variation of the eastern suburb of Xi’an showed four stages of variation characteristics in April and May.The average concentration of nitrogen oxides in April was 0.075 mg/m3. The average concentration was 0.023-0.142 mg/m3.The average concentration of the first stage (0:00-6:00) was 0.066 mg/m3, the variation range was 0.036-0.111 mg/m3. The average concentration of the second stage (8:00～12:00) was 0.091 mg/m3, the variation range was 0.049-0.142 mg/m3. The average concentration of the third stage (14:00～16:00) was 0.059 mg/m3, the variation range was 0.023～0.095 mg/m3. The average concentration of the fourth stage (18:00～22:00) was 0.080 mg/m3, the variation range was 0.044～0.127 mg/m3.In May, the average concentration of nitrogen oxides was 0.072 mg/m3,the variation range was0.019～0.123 mg/m3. The average concentration of the first stage (0:00-6:00)was 0.076 mg/m3, the variation range was 0.047～0.109 mg/m3. The average concentration of the second stage (8:00～12:00) was 0.083 mg/m3, the variation range was 0.055～0.122 mg/m3. The average concentration of the third stage (14:00～16:00) was 0.053 mg/m3, the variation range was 0.019～0.084 mg/m3. The average concentration of the fourth (18:00～22:00) stage was 0.078 mg/m3, the variation range was 0.046～0.123 mg/m3.(2) The concentration of sulfur dioxide circadian variation of the eastern suburb of Xi’an showed four stages of variation characteristics in April and May.The average concentration of sulfur dioxide in April was 0.034 mg/m3. The average concentration was 0.017～0.051 mg/m3.The average concentration of the first stage (0:00～4:00) was 0.035 mg/m3, the variation range was 0.021～0.051 mg/m3. The average concentration of the second stage (6:00～12:00) was 0.036 mg/m3, the variation range was 0.020～0.051 mg/m3. The average concentration of the third stage (14:00～18:00) was 0.029 mg/m3, the variation range was 0.017～0.041 mg/m3. The average concentration of the fourth stage (20:00～22:00)was 0.032 mg/m3, the variation range was 0.019～0.045 mg/m3.In May, the average concentration of sulfur dioxide was 0.031 mg/m3, the variation range was 0.014～0.049 mg/m3. The average concentration of the first stage (0:00～4:00) was 0.033 mg/m3, the variation range was 0.017～0.045 mg/m3. The average concentration of the second stage (6:00～12:00) was 0.035 mg/m3, the variation range was 0.018～0.049 mg/m3. The average concentration of the third stage (14:00～18:00) was 0.025 mg/m3, the variation range was 0.014～0.035 mg/m3. The average concentration of the fourth stage (20:00～22:00)was 0.031 mg/m3, the variation range was 0.019～0.044 mg/m3. nitrogen oxides and sulfur dioxide concentrations at night (20:00pm～next day 6:00am) was higher than day (8:00am～18:00pm), nitrogen oxides and sulfur dioxide concentrations at morning (8:00am～12:00am) was higher than Afternoon (14:00pm～18:00pm), It found that the mean concentrations of nitrogen oxides and sulfur dioxide in April were higher than May, and the change range in April was larger.(3)With the increase of altitude, nitrogen oxidesconcentrations increased in April and May. There was significant positive correlation between nitrogen oxides concentrations and altitude. In three stage of 0～19m、22～55m and 58～70m, The average concentration of the first stage was 0.063 mg/m3, the variation range was 0.028～0.113 mg/m3. The average concentration of the second stage was 0.077 mg/m3, the variation range was 0.041～0.131 mg/m3. The average concentration of the third stagewas 0.068 mg/m3, the variation range was 0.034～0.105 mg/m3.With the increase of altitude, sulfur dioxide concentrations increased in April and May. There was significant positive correlation between sulfur dioxideconcentrations and altitude. In three stage of 0～19m、22～49m and 52～70m, The average concentration of the first stage was 0.025 mg/m3, the variation range was 0.014～0.034 mg/m3. The average concentration of the second stage was 0.037 mg/m3, the variation range was 0.022-0.054 mg/m3. The average concentration of the third stage was0.032 mg/m3, the variation range was 0.018～0.048 mg/m3.(4) In April, nitrogen oxides concentrations of the eastern suburb of Xi’an usually at the variationrange of 0.023～0.142 mg/m3, the first over standard rate of nitrogen oxides was 8%. In May, nitrogen oxides concentrations of the eastern suburb of Xi’an usually at the variation range of 0.019～0.123 mg/m3, the first over standard rate of nitrogen oxides was 0%. In April, sulfur dioxide concentrations of the eastern suburb of Xi’an usually at the variationrange of 0.017～0.051 mg/m3, the first over standard rate of sulfur dioxide was 0%. In May, sulfur dioxide concentrations of the eastern suburb of Xi’an usually at the variationrange of 0.014～0.049 mg/m3, the first over standard rate of sulfur dioxide was 0%.(5) The eastern suburb of Xi’an in the Spring, a positive correlation could be found between nitrogen oxides andsulfur dioxide concentrations and temperature,correlation coefficient were 0.83 and 0.67.The eastern suburb of Xi’an in the Spring, There was negative correlation between nitrogen oxides and sulfur dioxide concentrations and relative humidity, correlation coefficient were -0.75 and -0.48.(6) It is found that the mean concentrations of nitrogen oxides were higher than sulfur dioxide, and the change range nitrogen oxides was larger. There was Positive correlation between nitrogen oxides concentrations and sulfur dioxide. |
PDF Full Text Request