Volume 14, Issue 1 (3-2023)                   2023, 14(1): 19-30 | Back to browse issues page


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Department of Biology, Payame-Noor University, Tehran, Iran.
Abstract:   (748 Views)
Abstract
Accumulation of heavy metals in medicinal plants can have dangerous consequences for human health. This study investigates the concentration of heavy metals including zinc, lead, copper, and cadmium in the soil, aerial parts (shoot), and roots of the medicinal plants Phlomis olivieri Benth. and Stachys inflata Benth. around the Zeh-Abad lead and zinc mine in Qazvin province. The soil and plant samples were collected and prepared, and the total concentrations of heavy metals in the samples were measured by an atomic absorption spectroscopy in three replicates. The results showed that, unlike copper and cadmium, the concentrations of lead and zinc in the soil, shoot, and roots of the studied plants were several times greater than the standards (i.e., EPA and WHO). The average concentrations of zinc and lead in the contaminated soil were 1791 and 2855 mg/kg, respectively. The average concentrations of zinc and lead in the roots of Ph. olivieri were 394 and 56 mg/kg, respectively, and in the shoot of this plant were 442 and 76 mg/kg, in the roots of S. inflata, were 452 and 38 mg/kg, and in the shoot of this plant were 501 and 68 mg/kg, respectively. The highest concentration of zinc was measured in the root of S. inflata (i.e. 694 mg/kg) and the highest concentration of lead was determined in the shoot of Ph. olivieri (i.e. 140 mg/kg). The transfer factor values for the lead and zinc in both plants were higher than one; in the case of the copper and cadmium, its values were lower than one. Considering the harvesting of these two medicinal plants by the native people in the region, the results of this study can be a warning for the health of these people.

Background and Objective: These days, releasing heavy metals in the biosphere is one of the most critical environmental concerns. The accumulation of heavy metals in plants, animals, and the environment, directly and indirectly, affects human health. Plants absorb these heavy metals from soil and polluted environments and accumulate them in their edible parts (1). If medicinal plants are collected and consumed from areas contaminated with heavy metals, they can be one of the essential sources of transfer of the heavy metals to humans. With the increase of mining activities in different parts of the country, plants are at risk of heavy metals accumulation (2). Two plants, Ph. olivieri and S. inflata, grow naturally in the area of the lead and zinc mine of Zeh-Abad in Qazvin province. Considering the medicinal value of these plants, this study aims to determine the accumulation of heavy metals in their different organs.

Methods: Soil samples were collected from four plant-growing areas around the Zeh-abad lead and zinc mine in 3 replicates. Soil samples were collected and prepared and, the total concentrations of heavy metals including zinc, lead, copper, and cadmium were measured by an atomic absorption spectroscopy. Two medicinal plants, Ph. olivieri and S. inflata, were sampled from four regions around the lead and zinc mine with three replicates. The total concentrations of lead, zinc, copper, and cadmium in the root and shoot of the studied plants were measured by the atomic absorption spectroscopy. The transfer factor (TF) was calculated by dividing the element concentration in the shoot by its concentration in the root. Statistical data analysis was done using SPSS 16.0 software and one-way analysis of variance followed by Duncan's multiple range test at a significance level of 0.05.

Results: The results showed that the concentrations of lead and zinc in the soil of the mining area were significantly higher than control. According to EPA standard, the concentrations of copper and cadmium were within the allowable range. However, the concentrations of zinc and lead in the root and shoot of the contaminated plants were much higher than the control. The highest concentrations of zinc were found in the root and shoot of S. inflata and the lowest values were recorded in the root and shoot of Ph. oliveri. Unlike zinc, the concentration of lead in the root of S. inflata was greater than that of Ph. oliveri. The concentrations of copper and cadmium in the root and shoot of both plants in the contaminated areas were not significantly different from the control plant. The TF values calculated for the studied heavy metals showed that Ph. oliveri and S. inflata tend to accumulate lead and zinc in the shoot than in the root, so that the TF values for these two elements were higher than one. However, the TF values for copper and cadmium in both investigated plants were less than one in all habitats.

Conclusions: The results of this study showed that the release of heavy metals due to years of mining activity has led to soil and plant pollution in the area. One of the critical issues that need more attention is the harvesting of broad medicinal plants by people without knowing the possibility of their contamination with heavy metals. Such harvests, while reducing plant biodiversity, lead to pollution transmission to humans. Such studies can be a warning for the use of medicinal plants from their natural habitats.

References:
1. Abrham, F., Gholap, A., 2021. Analysis of heavy metal concentration in some vegetables using atomic absorption spectroscopy. Pollution 7(1): 205–216.
2. Haiyan, W., Stuanes, A., 2003. Heavy metal pollution in air-water-soil-plant system of Zhuzhou City, Hunan Province, China. Water Air and Soil Pollution 147: 79–107.
 
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Type of Study: Research | Subject: Soil health association with soil-plant interactions
Received: 2023/01/14 | Accepted: 2023/03/30 | Published: 2023/06/18

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