The Heavy Metal Accumulated Sequence Of Typical Vegetation Tree-rings And Environment Significance And EKC Analysis From Southeast Chongqing In Decades

The paper choose three common tree species from different growth environment of You Yang county, pick off the tree-rings since2000-2012and the corresponding bark as the research object. On the basis of field investigation, sampling and laboratory analysis, the author investigated the content level, dynamic change, the relationship between heavy metal (Cu, Cr, Cd, As, Fe, Al, Zn, Pb) of tree-rings and climate records in decades, Environments Kuznets Curve of the heavy metals of tree-rings of three typical vegetation from different environment in Southeast Chongqing.The author made following research in this paper. The author mainly introduced the background, significance, the current situation and developmental trend of the dendrochemistry analysis, and put forward the content and meaning of this paper. Mainly introduced the background of the study areas, including the natural environment characteristics, socioeconomic status and the developing situation of the city. The sampling selection and site, collecting tree-rings, samples pretreatment, experimental projects and determination methods were also introduced in this paper. Comprehensively discuss and analyze the heavy metal content accumulated sequence, time-series analysis, climate record response in recent years, Environmental Kuznets Curve of the tree-rings from different environment areas.The main conclusions can be drawn from what has been discussed above:(1)The variability of heavy metal of tree-rings in the different environmental areas of You yang county in recent ten years was divided into two types, one type is moderate intensity variation and strength variation (Cr, As, Cd, Fe, Al), the other type is moderate intensity variation(Zn,Pb),of which Al show the samples in half as moderate intensity variation and half as strength variation. Cr,As,Fe maximum value of tree-rings is near the road tree wheel samples, while the maximum value of Cd,Al,Zn,Pb of tree-rings is near rural settlement samples..In the context of different environment of different tree species, Cr, As, Fe of tree-ring samples near the road showed strength variation, the variability of Cd,Al elements near the near rural settlement were strength., moreover the variability of Zn and Pb from the two different growth environment were moderate intensity; In terms of average, the contents of Cr,As,Al of tree-ring samples near the road is greater than the rural settlement, on the contrary, the contents of Cd,Fe,Zn,Pb of tree-ring samples near the rural settlement is greater than the samples near the road. The average order of heavy metal elements in different tree species were:Cr, As: Fir>Cypress>Pinus massoniana;Cd,Fe,Al,Zn:Fir>>Pinus massoniana>Cypress; Pb: Fir=Pinus massoniana>Cypress. We can find that heavy metal element of Fir is stronger enrichment than the other two species. Heavy metals of tree-rings mainly comes from traffic pollution, agricultural chemical pollution, people’s daily life waste, pollution of rural construction and mining exploration pollution.(2)By analyzing the time series of heavy metal of tree-rings from You Yang County in recent ten years. The author come to the conclusion that the maximum value heavy metal elements of most tree-rings are in the barks or near the rings of tree bark. This suggests that the bark is one of the main channels of heavy metals into the trees. Test of sever heavy metals are presented in the fluctuation changes in recent years. In recent ten years, the value of Fe, Zn, and Pb vary strongly and present the change trend of ups of downs.(3)The correlation and historical trend diagram analysis of heavy metal element of tree-rings and climate records of all tree-ring samples, the result showed that the correlation relationship of heavy metals of tree-rings and the temperature is very complicated, besides Cd has good corresponding relation with the temperature, the other heavy metal elements and temperature appear different changes between positive and negative correlation in different stages. Most of samples have1-2a lag period changes between heavy metals and temperature, and a temperature trough and the heavy metal element content peak appeared at the same time more years, that illustrate that low temperature can contribute to the enrichment of heavy metals. There was an inverse correlation between Cd and precipitation in the vicinity of residential areas, while it’s has a good corresponding relationship in the vicinity of road. Between Al, Zn and precipitation have good corresponding relation, Pb on the contrary, give priority to with negative correlations. The first and last of Fe is negative changes, and change the middle to good corresponding. Cr as appeared negative and positive correlation in multiple stages. Precipitation has inhibitory effect on heavy metal enrichment, for more years appear trough with peak at the same time.(4)The Environmental Kuznets Curve between the variation in heavy metal elements contents of the tree-rings and per capita GDP of You yang showed that there was a significant cubic polynomial correlation between the elements (Cr, Cd, Zn, Pb) variation of tree-rings in content and per capita GDP, the curves displayed obviously characteristics of environmental Kuznets curve. The regression curve (Cd, Pb) was on the left part of the inverted "U" type curve. The fitting curve between Zn, Cr and per capita GDP were inverted" and "N" type, it is belong to a variation form of the EKC.