| مستخلص: |
The annual tree rings are used to reconstruct the history of the past climate and the impact of climatic and environmental changes on tree growth. Several conifer and broad leaf tree species (e,g. Abies densa, Larix griffithiana, Pinus merkusii, P. kesiya, P. wallichiana, Quercus serrata, Toona ciliata, and Tectona grandis) have been used for diverse dendrochrological studies in Northeast India (NEI). Tree rings act as bio-indicator of changes in soil chemistry due to anthropogenic activities in urban and peri-urban areas because of rapid population growth, agricultural intensification, and industrialization. Most of the earlier studies in NEI are available with respect to the climate-tree growth relationship, however, aspects like tree ring relations with pollution history have not been attempted so far. Considering this gap, the present study has been carried out to investigate the concentration of toxic elements in tree rings. Particularly in this study, we used Magnolia champaca (Champak) tree rings to reconstruct the temporal distribution of 7 elements (Zn, Pb, Fe, Cu, Ni, Ca, and Mn) at the Tuirial dumping site in Aizawl, Mizoram. A total of 20 trees were sampled by taking two cores from each, and the dated samples covered a period of two decades from 1999 to 2019. We used an Atomic Absorption Spectrometer (AAS) to quantify concentrations of toxic elements in the tree-rings over different years. The findings indicated a rising pattern of elements in conjunction with increasing tree age, for example, the largest concentration of harmful elements was located in recent year ring growths. The range of element accumulations was: 20.46 to 30.10 mg/kg for Fe, 16.19 to 28.24 mg/kg for Mn, 13.86 to 27.4 mg/kg for Zn, 9.02 to 17.08 mg/kg for Ni, 6.08 to 14.69 mg/kg for Cu, 7.33 to 14.35 mg/kg for Ca, and 6.92 to 14.26 mg/kg for Pb. The present study indicated that Pb, Fe, Ni, and Cu exceeded the acceptable thresholds set by the World Health Organization (WHO) for harmful components in the plant. Based on the findings, we recommend Magnolia champaca as a suitable species for plantation in degraded/polluted areas as an efficient biocontrol agent for the removal of toxic elements. [ABSTRACT FROM AUTHOR] |
