Document Type : Research Paper
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Abstract
Background and aim: Every year, large amounts of species adapted to the semi-arid environment of Tehran planted. Meanwhile, planted oriental plane and eldar pine trees 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 oriental plane 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 oriented plane trees were randomly cut down in planted forest region from District 4 of Tehran city. 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 orient plant and aldar pine tree.
Results: The results showed that the most ash was found in oriental plane bark and the least in oriental plane wood. The highest amount of iron ion absorption was found in oriental plane leaves, while the lowest amount of iron ion absorption was found in oriental plane 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 in eldar pine bark. The amount of potassium ion absorption in eldar pine leaves was higher than its wood and bark, and in oriental plant, bark is higher than its wood and leaves. In addition, the absorption of potassium ion is more in oriental plant than in eldar pine. The highest amount of copper ion absorption was observed in eldar pine leaves and the lowest amount was observed in oriental plant 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 oriental plant. The highest amount of lead ion absorption was observed in the bark of eldar pine and the lowest amount was observed in oriental plant 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 oriental plant. 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 oriental plant 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 oriental plant.
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 wood and oriental plant tree 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 oriental plant.
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