Studies On Soil And Atmosphere Environment In Different Green Land In Beijing

Urbanization is the necessary trend of the development of human society and economy, and it is also a necessary phase that a country tends towards modernization. It brings the human society with great progress and substantial civilization as well as a series of severe environment problems at the same time. The article studied the soil and atmosphere environment through surveying and sampling, and analyzed physicochemical properties and microelements of different greenbelt soils, as well as air pollution, heat island effect and urban microclimate in Beijing, which has provided scientific basis and guidance for a good ecological environment.As a result of human influence, the physicochemical properties of greenbelt soil in Beijing are obviously not as good as that of natural mountain soil, Urban soil has lost some characteristics of natural soil, such as soil density, PH value, calcium and phosphorus content increasing significantly, soil alkalized more seriously and nutrient shortage, From the physical properties, the porosity and permeability of urban soil has decreased significantly, from acidity and alkalescence of the Soil , the pH value of various Greenbelt types of soil In Beijing is more than 8.0, the soil is alkaline, but natural mountain soil is neutral soil, therefore the soil in Beijing alkalized more seriously. The organic matter content and total nitrogen content in urban soil has decreased significantly by comparing with the nutrient of the mountainous soil, But the quick result phosphorus and calcium content of soil have been significantly increased, there were little difference of the quick result K, soluble salt and magnesium content in different types of greenbelt soil.We can see from the change of microelement in soil, that there was obvious difference of the microelement content between the urban oil and natural mountain soil, which has gradually influenced by human factors and caused pollutions. The chromium content of the urban soil is significantly lower than natural mountain soil, the nickel and cobalt in green area for environmental protection are significantly higher than that in the scenic mountain forest soil, and other types of greenbelt soil have not noticeably changed, Greenbelt protection arsenic and boron content is also higher. In all types of greenbelts, the mercury and cadmium content in public green soil is relatively higher, but in scenic mountain soil the presence of the two kinds of heavy metals have not detected. As for iron, manganese, copper, zinc, lead, and aluminum and other microelements, there are not significant differences between urban soils and the natural mountain soils, which has showed a lesser influences by human, and yet has not changed significantly.Because of the influence of the atmospheric environmental, the changes of the elements of climate between seasons in different types of urban greenbelt trends were the same. Compare with the square, temperature in boulevard is more suitable, and changes gently. The high-temperature persists during a short time, The adjustment of the air temperature and humidity increased significantly, and its effect on sunny and cloudy days are quite apparent. At night it is difficult to ventilate for place with boulevard, so it can preserve heat. As the lawn can not keep out solar radiation, its regulation on temperature is not apparent, and its effect of cooling and humidifier gradually emerge with intensity of radiation reducing, but it has a strong humidifying effect in the evening.With the development of the city, the average temperature in Beijing is rising gradually. The average of urbanization in low-speed (1985 years ago), fast urbanization (1986～1993), accelerated urbanization (1994-2000) and developed period of the city (after 2000) is 12.01 ℃, 12.66 ℃, 13.11 ℃ and 13.14 ℃, and the temperature in Beijing has strong positive correlation with Beijing's population. At the same time by comparing the city and the suburbs, the temperature contrast in daytime is 0.67～0.70 ℃, and at night is up to 1.52～1.79 ℃. The heat island intensity variation has a strong performance at night, and weak at noon in the daytime, which is similar with relevant research results.Beijing's primary pollutant is particles of pollutants, the content of SO2, CO, and PM₁₀ decrease gradually, which is below the second grade of the national standard. The daily average levels of PM₁₀ and TSP are higher than the national standard two, and it need further improvability, but the other major pollutants is lower than the second grade of the national standard currently. Surveying the air pollution index 2001 - 2006, the air quality in 2003 and 2005 is good, but the API in the other years is 102.99～113.2, the air quality is III 1, and is in low pollution. From the seasonal changes, there is abundant rainfall in summer, the air quality is good, but there are more sandstorms in Spring and Autumn, the air quality is rather poor.