Identifying and measuring the amount of heavy metals in soil and ornamental plants in high-traffic squares of Mashhad (Case study: Squares of Revolution, Anti, Flake Ab, Taghi Abad)

Soil is the main source of organic and mineral substances in the earth and the natural environment for the growth and development of plants, and in addition, it is an important platform for other developmental activities. Heavy metals are a group of metals that are highly toxic to the health of human societies and the environment. Heavy metals can be said to exist naturally in the soil because they are brought into the dry environment by geological processes such as volcanoes, erosion of underground materials, etc. Heavy metals accumulate in soil and plants at different times and can have a negative effect on the physiological activities of plants (such as photosynthesis, gas exchange and absorption of nutrients), plant growth and its yield. Heavy metals accumulate in soil and plants at different times and can have a negative effect on the physiological activities of plants. Lead, arsenic and cadmium are examples of heavy metals. This substance is one of the metals that exist in nature in a very large amount. Lead is known as a potential poison of the nervous system due to its major effect on different parts of the central nervous system. Arsenic is one of the heavy metals that has a high level of toxicity, this metal leads to disorders such as blood circulation, nervous system, acute poisoning and death. Heavy metals are a group of metals that are highly toxic to the health of human societies and the environment The biological availability of the total amount of heavy metals as well as the man-made amount of these metals gives information about environmental pollution, but what is more worrying is the amount of metals that enter the food cycle and body of organisms, especially humans, through water, soil and sediment.. Although these metals exist naturally in different environments, but various natural and anthropogenic factors lead to their excessive increase in air, water and soil environments all over the world. The industrialization of cities, the increase in traffic in metropolises, etc. are among the effective factors in increasing the amount of pollution from different sources. Metropolises such as Mashhad located in Razavi Khorasan province are among the cities that face high levels of pollution due to various reasons such as high traffic. In this research, the heavy metals cadmium, lead and arsenic were measured in the root organs, stems and petals of the rose ornamental plant, as well as the soil, in 4 high-traffic square of Zed, Taghi Abad, Flake Ab and enghelab.

The statistical population of selected soil and plants was selected from 4 high-traffic squares of Mashhad city and Shahid station in low-traffic areas. Sampling was done in compound form and by plastic shovel. The soil samples were dried in the open air and after 24 hours at 40 degrees Celsius and passed through a 63 micron sieve and used for complete analysis and chemical separation. For Preparation of plant samples, the samples were immediately transferred to the laboratory after harvesting. First, they were washed with ordinary water, then they were washed with 0.1 M Hcl or some ordinary detergents (dishwashing liquid), then they were drained again with ordinary water and distilled water. After drying in air in an oven at 70°C for 48 hours, the samples were then ground. The amount of heavy metals was measured with an atomic absorption device.

The results of the investigations showed that among the 4 high-traffic squares, Falakeh Ab Square, Enghelab Square, Zed Square, and Dr. Ali Shariati Square, also known as Taghiabad Square in Mashhad, the soil of Enghelab Square has the highest amount of lead, and the soil of Taghiabad Square has the lowest amount of lead. Considering that the control sample was taken from the soil of the plains around Mashhad, the contamination was much lower. Soil lead has a traffic origin and is caused by car fuel, with the removal of lead from fuel, its amount has decreased significantly, but it is still accumulated in the soil. The results of the investigations showed that among the 4 high-traffic squares, Falakeh Ab Square, El Enghelab Square, Zed Square, and Dr. Ali Shariati Square, that is, Taghi Abad Square had the highest amount of lead accumulation in the stem of rose plants, and seen that lead accumulation in Enghelab Square, and the lowest is in Taghi Square. In the case of cadmium metal, the highest accumulation is related to Zed Square and the lowest is related to the roses of Taqi Abad Square. The highest accumulation of the heavy metal arsenic is related to the roses of Falakeh Ab and the lowest is related to the roses of the Revolution Square. The results of the investigations showed that among the 4 high-traffic squares of Falakeh Ab Square Enghelab Square, Zed Square and Dr. Ali Shariati Square, that is, Taghi Abad Square, Mashhad, the highest concentration of lead is related to rose petals in Enghelab Square, and the lowest is related to the rose petals of Taghi Abad.The results showed that the highest concentration of these metals after the soil is in the root of the rose plant. Transfer coefficient is the ability to move a heavy metal from one environment to another environment. The transfer coefficient was calculated for lead: stem < petal < root, for cadmium petal < stem < root and for arsenic: petal < stem < root. Rose plant could use as an accumulators of heavy metals in high traffic area.The results of statistical tests show that the significance level for the accumulation in the soil is less than 0.05, so the assumption of the equality of the average in the two control and experimental groups can be rejected, that is, traffic has a significant effect on the accumulation of metals in the soil of plants, considering that the test statistic is positive, so Traffic increases the accumulation of metals in the soil of plants. The significance level for the accumulation in the roots is less than 0.05, so we can reject the assumption of the equality of the averages in the two control and experimental groups, that is, traffic has a significant effect on the accumulation of metals in the roots of plants, considering that the test statistic is positive, so Traffic increases the accumulation of metals in the roots of plants.