Study On Dynamic Of δ¹³C And The Lead Content In Annual Rings Of 65-year Old Tree Of Ailanthus Altissima In Hefei City

Stable carbon isotopes of Environmental Science is the world's hot spots and areas of a frontier,China's forestry is the further development of a direction.Based on the growth in Hefei area targeted Ailanthus aitissima tree rings,from tree rings start of stable carbon isotopes,application of stable carbon isotope fractionation principle,the basis of Ailanthus altissima tree rings in theδ13 C at that time may reflect the concentration of atmospheric carbon dioxide.Lead content and precipitation in the study of lead content is accumulated principle applied to the basis of practice.According to the annual precipitation of lead content and the relevance of the results,you can determine the lead content of the accumulated scientific principles applied in practice;according to the annual precipitation of lead content and the relationship between modeling,and can lead content in the return of precipitation Analysis in order to achieve the objective of improving the model.Therefore,the study of lead content and the relationship between the annual precipitation from the lead content in the first year of precipitation and the analysis of the correlation.China's research in this area in less than,as part of the global environmental system is necessary to conduct further study.Lead content and precipitation in the study of lead content is accumulated principle applied to the basis of practice.According to the annual precipitation of lead content and the relevance of the results,you can determine the lead content of the accumulated scientific principles applied in practice;according to the annual precipitation of lead content and the relationship between modeling,and can lead content in the return of precipitation Analysis in order to achieve the objective of improving the model.Therefore,the study of lead content and the relationship between the annual precipitation from the lead content in the first year of precipitation and the analysis of the correlation.Based on chemical analysis of heavy metal Pb in 60-year ring set of Ailanthus altissima growing in the center of downtown of Hefei city,the study on dynamic characteristics of Pb concentration in ring set was done.The results showed that the average concentration of Pb in ring set reached 0.668 mg.kg^-1,which was obviously higher than that in Huangshan pine tree growing in nature site,it also indicated that Hefei city has more metal pollution problem,Pb accumulation in ring of the tree is fluctuation with years,it ranged from 0.098 rag.kg^-1 to 1.42;Pb contents in 47%of total rings is less than 6 mg.kg^-1:Pb contents in rings in the periods of 1951-1960,1973-1978 and 1985-1990 was higher than the average,which just in the period of more rapidly development of economy and city scale;However Pb accumulation in the whole ring set had a downward trend,it follows that Pb pollution has been improved;there is no relationship between Pb concentration in rings and tree age or ring growing width;but it was found that there is significance relation between Pb concentration in rings and annual precipitation.At the same time based on the old growing up in Hefei city Ailanthus altissima 60-year rings of trees in the sequenceδ¹³C value of the analysis,researchδ¹³C ring in the value of the dynamic features.The tree-ringδ¹³C in the average -22.85,and the majority ofδ¹³C in the average value,a peak of the ring for the 1965-1972 and 1977-1988,respectively, happens to be the city an economic recession,urban development and even slow production Retrogression in the historical period,show that urban economic development is the productionδ¹³C -ring led to an increase in value,butδ¹³C value increases with age show the trend very clearly,only a very weak performance of the decreasing trend,almost Excluding overlooked that in urban areasδ¹³C values not only by the impact of atmospheric carbon dioxide concentration and other factors,reflecting the city's unique local environment.δ¹³C values in the ring with the old,ring width and the local annual average precipitation,but some obvious peaks and trough ofδ¹³C values and the corresponding growth rings of the ring width and the local annual average precipitation even Pb content,according to stable carbon isotope fractionation model principle,can be analyzed to have a certain link,and some do not meet the general needs of the local provide a reasonable explanation,and worthy of further study.This article is the first time a key measure of the Hefei City Ailanthus altissima tree-ring width of the ring,and in accordance with the definition of ring index calculated index of the ring,after further study for the work of accumulated data.