Document Type : Research Paper
Author
Associate Prof., Dept. of Wood and Paper Science and Technology, Islamic Azad University of Chalous, Chalous, Iran
Abstract
Background and aim: Every year, large amounts of species adapted to the semi-arid environment of Tehran planted. Meanwhile, planted plane tree (Platanus orientalis) and eldar pine (Pinus Halepensis var. Eldarica) tree in Tehran, in addition to creating a green and lively urban space, can also play a big role in absorbing heavy metals and components in the polluted air of Tehran. This study and it aim was accomplished on identification and comparison of the heavy metals in the wood, bark and leaves of planted plane tree and eldar pine tree by using flame atomic absorption method.
Materials and methods: In this study, 20 separate test samples of leaves, wood, and bark of planted elder pine and plane tree were randomly selected from the 4th district of Tehran. According to the TAPPI standard tests, the leaf flour, wood and bark of the samples and their ash percentage were measured. Then with the help of 63% nitric acid and for one hour, the solution containing heavy metal was separated from the ash. In this research, atomic absorption spectrophotometer was used to determine the type and percentage of metal ions absorbed in the wood, bark and leaves of plane tree and eldar pine tree.
Results: The results showed that the most ash was found in plane tree bark and the least in plane tree wood. The highest amount of iron ion absorption was found in plane tree leaves, while the lowest amount of iron ion absorption was found in plane tree wood. The amount of iron ion absorption in eldar pine bark is more than its wood and leaves and in oriental plane leaves is more than its wood and bark. The highest amount of potassium ion absorption was observed in eldar pine leaves and the lowest was in eldar pine bark. The amount of potassium ion absorption in eldar pine leaves was higher than its wood and bark, and in plane tree, bark is higher than its wood and leaves. In addition, the absorption of potassium ion is more in plane tree than in eldar pine. The highest amount of copper ion absorption was observed in eldar pine leaves and the lowest amount was observed in plane tree wood. The rate of absorption of copper ions in leaves is higher than the bark and wood of both species. In addition, the absorption of copper ions in eldar pine is more than that of plane tree. The highest amount of lead ion absorption was observed in the bark of eldar pine and the lowest amount was observed in plane tree and eldar pine wood. The amount of lead ion absorption in the bark was more than in the leaves of both species and in eldar pine was more than in plane tree. The highest amount of zinc ion absorption was found in oriental plant leaves and the least in oriental plant wood. The rate of absorption of zinc ions in the bark of eldar pine is more than its leaves and wood and in oriental plant leaves is more than its bark and wood. The highest amount of nickel ion absorption was found in plane tree and elder pine leaves and the lowest in oriental plant wood. The rate of absorption of nickel ions in oriental plant and eldar pine leaves is higher than in their bark and wood. In addition, between the two species, the rate of absorption of nickel ions in eldar pine is higher than that of plane tree.
Conclusion: So that, the results showed that the leaves and bark of both species have a great role in the absorption of heavy metal in the air. In addition, the importance of the eldar pine species in absorbing heavy metal such as nickel, zinc, lead, iron and copper is more than the plantain species due to its evergreen nature. Eldar pine and plane tree wood showed the least importance in absorbing heavy metal. While the importance of bark in absorbing lead is the highest. In other words, in urban areas like Tehran, where air pollution is very important, planting eldar pine species seems to be more effective than plane tree.
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