Investigate the effect of distance from source and species type on the absorption ability of heavy metals by tree species around Nahavand cement factory

This study aims at investigating the effect of distance from source, species type and soil physical chemical properties on the absorption ability of heavy metals by tree species around the Nahavand cement factory. In the present research, soil and tree leaf (Pseudoacacia L, Populus nigra L, Elaeagnus angustifolia L, Fraxinus excelsior and Thuja orientalis L) samples were taken from 300, 500, 800, 1000 and 2000 m distances from Nahavand cement factory and after preparation and digestion of samples, the concentration of heavy metals (Cd, Mn, Ni and Zn) were measured using atomic absorption spectrometry. Also for soil samples; pH, EC and organic matter were calculated. The effect of distance, species, and soil physical and chemical properties on the heavy metals accumulation was investigated using Kruskal-Wallis test. In order to determination the species with the highest accumulation, the Metal Accumulation Index and Bio Concentration Factor indices were used. The results showed, that there is significant differences among the heavy metals in the leaf in various tree species (p <0.05). Based on the results, the effect of distance on heavy metal accumulation in the studied species was significant for some heavy metals. According to the metal accumulation index, the Thuja orientalis L species had a higher accumulation for all of  the heavy metals, and according to the Bio Concentration Factor index values, the studied species are considered as moderate accumulator for Cd, Mn and Zn. Considering being significant the effect of distance and species type and also the relationship between soil physical and chemical properties and heavy metals in the tree leaves, these factors should be considered when control systems for designing and planting were used for polluted areas. Due to the high capacity of the Thuja orientalis L, is recommended for pollution control in contaminated areas with several heavy metals.