Influence Mechanism And Effectiveness Of The Plants Semi-arid On Detaining Dust In Beijing

Along with the rapidly economic development, ecological environment deteriorates day by day. The dust in air threats the people's physical fitness, especially in urban. Analysis of the averages of the dust pollution in four different regions in China, we can see that the pollution average is lower in southern city than in the northern. The dust pollution is serious in northern city, the representative weather is dust storm.The greenery species can detain dust in the air. Take the northern city Beijing to study the influence mechanism and effectiveness about the detaining dust of the greenery species for example. Sixteen kinds of representative plants were chosen to be studied in Beijing, which were divided into three classes along to the blade feature of leaf. The first are the evergreen trees that can excrete mucous substance, including Pinus bungeana Zucc.ex Enll. , P. tabulae formis Carr.,Platycladus orientalis (L.) Franco and Sabina chinensis cv. 'Globosa'. The second is Platanus occidentalis L., the broad-leafed plants that there is fuzz in the blade. The third are the broad-leafed plants that the blade is smooth, including Fraxinus bungeana DC, Buxus microphylla Sieb, Syringa reticulata var. mandshuica, Sophora japonica L. Ginkgo biloba L., Rosa multiflora Thunb., R. chinensis Jacq, Weigela florida (Bunge) A. DC., Cercis chinensis Bunge, Berberis thunbergii DC and Lonicera maackii (Rupr.) Maxim. We choose the Beijing forestry university as the sampling place which locates in the Haidian Qu of Beijing city. In order to research on the dust detaining capability and its rule of different leaves in different plants, some representative greenery species in Beijing were chosen to systematically study the accumulation of dust on the leaves of different plants in opening and enclosure surroundings by direct sampling and measurement, and statistical analysis as well, The results show that: 1) the amount detaining dust per square meter of leaves vary significantly at large contributing to the strong disturbance of external environment; 2) for the same species dust detained on the leaves in the enclosed surroundings was obviously less than that in the open ones; illustrating that the amount detaining dust of leaves increase with increment of the particles in the environment. 3) In the open surroundings, the amount detaining dust of leaves at lower parts of the plants is evidently larger than that of the 'Middle' and 'High' parts of the same plant according to the comparison of dust detaining of different leaves vertically in the same plant, because, the dust that had landed down to the road was churned up by cars and people and dropped down to the leaves at the 'Low' parts of the plant again. 4) The cumulative dust detained on different plant leaves in one day period shows no linear relation with time, implying that thedust detaining process is complicated and dynamic. The leaves detain the dust and shake-out of it simultaneously. Understanding the dust detaining capability and its influence mechanism systematically can be of guidance to urban landscapingGarden plants can detain the dust in the air, which cleans the air. The purifying function can be assessed by the quantification data. So the function of garden plants decreasing pollution in the air can be reacted by perceptual intuition. By the health benefit assessment of the garden plants adsorbing PM₁₀, it can be seen the garden plants in Beijing adsorbed 30,389,901 kg PM₁₀ in 2003. Because the garden plants adsorbed the PM₁₀, there were 2.81 persons can be free from death and 2.75 persons suffering respiratory system disease can be free from hospital. According to saving RMB ï¿¥892,960 one person who was free from death, saving RMB ï¿¥5,810 one person who was free from respiratory system disease, and there are 365 days one year. So it would save RMB ï¿¥917,055,650 one year for decreasing death persons, and save RMB ï¿¥5,832,683 one year for decreasing respiratory system disease persons. For the garden plants adsorbing PM₁₀ it saved RMB ï¿¥9.23 billion which is 2.56‰ of National gross product in 2003.The garden plants detaining dust is a new field, and a significant field, we can make a deep study by the methods of biology, chemical and so on. In summation, there is a wide area worthy of studying about the plants detaining dust.