The Application of Pinus tabulaeformis Tree Rings in Revealing the Pollution History of Chengde City
Chin J Plan Ecolo. 1994, 18 (4):
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The historical, air pollution of S and heavy metals since 1800 in the Chengde city was studied by analyzing the concentrations of S and heavy metals in the growth rings of Pinus tabulaeformis Carr. in the Summer Villa estate. The results showed that the S concentrations in the tree rings have elevated since the beginning of the 1900s (1900—1920). The S concentrations in the tree rings of 1810--1820, 1970—1980, and 1980—1990 have increased 1—2, 3—5 , and 10 times, respectively, of those in the tree rings of 1810--1920. At Bifengmen site, S increased significantly, from 40—50 μg· g-1 to 572.9μg·g-1. Such elevation indicated that the concentration of aerial SO2 of the City has increased from the very beginning of the urbanization. It is estimated that the aerial S concentration has increased from the pre-industrial background of less than 0.1 mg·m-3 up to the present>30 mg·m-3. This is ascribed to the result of urbanization especially the appearance and aggravation of industrialization in the city of Chengde since the 1950s. Fe appeared to have increased since 1927—1945, possibly due to the opening of Damiao Iron Mine by the Japanese; Mn increased throughout the whole history, from 4.1 μg·g-1(1840—1850)to 10.4μg·g-1 (1980—1990); Pb did not increase until 1980 but sharply elevated during the last 10 years; by 560%. It appears that the concentrations of Cu, Zn, and Ni have changed little. The concentrations of S and heavy metals in the tree rings at the beginning of 1800 were the lowest, and could be regarded as the background concentrations. It is calculated that S, Fe, Pb, Mn, Ni, Zn in the tree rings have increased 10, 2.4, 1.8, 1.5, 1.0 and 0.8 times, respectively, during the past 110 years or so. The svere air pollution, especially SO2, has resulted in air quality degradation, and also led to diebacks of the ancient pine trees in the Summer Villa estate.