Spatial And Temporal Variation Of Air PM 10 And SO 2 In Baoji City From April To May 2015

In order to study the temporal and spatial variation characteristics, rules and influence factors of PM₁₀, SO₂ concentration in Baoji city, we observed PM₁₀, SO₂ concentration in 46m height range in day and night for six times in April and May 2015 with the help of intelligent multi-function pocket LD-3C（L） dust meter and JSA8 portable SO₂ concentration detector, and used weather observation instrument to observe air temperature, relative humidity, wind speed and air pressure simultaneously. According to the observation data, professional theory analysis, correlation analysis, we researched the temporal and spatial variation characteristics, rules and reasons of PM₁₀, SO₂ concentration in Baoji city, and evaluated the air quality of PM₁₀ and SO₂.The main conclusions were as follows:（l）In April and May 2015, the day and night variation trend of PM₁₀ concentration from the ground to 46m height was consistent, which totally indicated bimodal distribution, and two highest values appear at 12:00 and 22:00, the lowest values appear at 16:00 and 18:00.Diurnal variation of PM₁₀ concentration could be divided into four periods in April 2015.The first period was 8:00-14:00, PM₁₀ concentration’s range was 40.0-132.Oμg/m3. the average concentration was 84.9μg/m3, this is the average concentration relatively high period. The second period was 16:00-18:00, PM₁₀ concentration’s range was 50.0-90.7μg/m3, the average concentration was 69.8μg/m3, this is the average concentration relatively low period. The third period was 20:00-0:00, PM₁₀ concentration’s range was 76.0-133.7μg/m3. the average concentration was 105.8μg/m3, this is the average concentration highest period. The fourth period was 2:00-6:00, PM₁₀ concentration’s range was 45.7-86.3μg/m3, the average concentration was 65.0μg/m3, this is the average concentration lowest period.Diurnal variation of PM₁₀ concentration could be divided into four periods in May 2015.The first period was 8:00-14:00, PM₁₀ concentration’s range was 47.3-120.Oμg/m3, the average concentration was 78.6μg/m3, this is the average concentration relatively high period. The second period was 16:00-18:00, concentration’s range was 51.7-87.3 μg/m3, the average concentration was 70.0μg/m3, this is the average concentration relatively low period. The third period was 20:00-0:00, concentration’s range was 69.0-123.3μg/m3, the average concentration was 94.8μg/m3, this is the average concentration highest period. The fourth period was 2:00-6:00, PM₁₀ concentration’s range was 38.3-75.7μg/m3,the average concentration was 56.9μg/m3, this is the average concentration lowest period.（2） Vertical variation of PM₁₀ concentration could be divided into three types in April 2015. The first type appeared in 10:00-14:00, the main characteristic is PMio concentration increased with altitude increased, the average increasing rate was 1.54μg/m3. The second type appeared in 8:00 and 18:00-20:00, the main characteristic is PM₁₀ concentration declined with altitude increased, the average declining rate was 1.27μg/m3. The third type appeared in 16:00 and 4:00-6:00, the main characteristic was PM₁₀ concentration emerged a very weak decrease trend with altitude increased, the average declining rate was 0.007μg/m3,it isfar less than the second type.Vertical variation of PM₁₀ concentration could be divided into three types in May 2015. The first type appeared in 12:00-14:00 and 18:00-20:00, the main characteristic is PM₁₀ concentration increased with altitude increased, the average increasing rate was 1.45μg/m3. The second type appeared in 22:00-6:00, the main characteristic is PM₁₀ concentration declined with altitude increased, the average declining rate was 1.21 μg/m3. The third type appeared in 8:00-10:00 and 16:00, the main characteristic was PM₁₀ concentration emerged a weak decrease trend with altitude increased, the average declining rate was 0.13μg/m3,it isfar less than the second type, and also present a large fluctuation.（3）In April and May 2015, the day and night variation trend of SO₂ concentration from the ground to 46m height was consistent, which totally indicated bimodal distribution, and two highest values appear at 12:00 and 18:00, the lowest values appear at 14:00.Diurnal variation of SO₂ concentration could be divided into third periods in April 2015.The first period was 8:00-10:00, SO₂ concentration’s range was 6.0-14.7μg/m3, the average concentration was 10.3μg/m3, this is the average concentration middle period. The second period was 12:00-18:00, SO₂ concentration’s range was 10.7-34.7μg/m3, the average concentration was 20.2μg/m3, this is the average concentration highest period. The third period was 20:00-6:00, SO₂ concentration’s range was 6.0-14.7μg/m3, the average concentration was 9.9μg/m3, this is the average concentration lowest period.Diurnal variation of SO₂ concentration could be divided into three periods in May 2015.The first period was 8:00-10:00, SO₂ concentration’s range was 4.0-19.0μg/m3, the average concentration was 11.0μg/m3, this is the average concentration middle period. The second period was 12:00-20:00, SO₂ concentration’s range was 8.0-30.7μg/m3, the average concentration was 17.3μg/m3, this is the average concentration highest period. The third period was 22:00-6:00, SO₂ concentration’s range was 3.3-14.3μg/m3, the average concentration was 8.0μg/m3, this is the average concentration lowest period.（4） Vertical variation of SO₂ concentration could be divided into three types in April 2015. The first type appeared in 8:00,14:00,20:00 and 0:00, the main characteristic is SO₂ concentration increased with altitude increased, the average increasing rate was 0.3μg/m3. The second type appeared in 12:00,16:00-18:00 and 6:00, the main characteristic is SO₂ concentration declined with altitude increased, the average declining rate was 0.39μg/m3. The third type appeared in 10:00,22:00 and 2:00-4:00, the main characteristic was SO₂ concentration emerged a very weak decrease trend with altitude increased, the average declining rate was 0.01μg/m3.Vertical variation of SO₂ concentration could be divided into three types in May 2015. The first type appeared in 16:00-22:00, the main characteristic is SO₂ concentration increased with altitude increased, the average increasing rate was 0.33μg/m3. The second type appeared in 8:00-14:00, the main characteristic is SO₂ concentration declined with altitude increased, the average declining rate was 0.39μg/m3. The third type appeared in 0:00-6:00, the main characteristic was SO₂ concentration emerged a very weak increase trend with altitude increased, the average increasing rate was 0.06μg/m3,concentration is almost unchanged as a whole.（5） PM₁₀ concentration had a negative relationship with temperature and wind speed in April and May 2015, at the same time it showed a positive relationship with relative humidity and air pressure, and SO₂ concentration had a negative relationship with temperature, relative humidity and wind speed in April and May 2015, but it showed a positive relationship with air pressure（6） PM₁₀ daily concentration and SO₂ daily concentration of Baoji City is 79.2μg/m3 and 12.9μg/m3 respectively,match less thandaily concentration of 《Ambient air quality standards》, so air quality was good in Baoji City during the observation period.（7）Though using multivariate linear regression model to predicted PM₁₀ concentration and SO₂ concentration, we got the regression equations, the regression equations of PM₁₀ was y=4576.68-9.26x1-0.84x2-0.94x3-44.93x4, the regression equations of SO₂ was y=-455.05+0.65x1-0.09x2-1.70x3+4.83x4 , These two equations can be used well to response concentration change, can be used to predict PM₁₀ concentration and SO₂ concentration of Baoji City.