نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 عضو هیات علمی مرکز تحقیقات کشاورزی و منابع طبیعی استان یزد
2 مدیرعامل بازار آب یزد
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objective: Heavy metals in agricultural soils may be naturally present in the soil under the influence of the soil parent materials (geogenetic) or may be added to the soil as a result of human activities (anthropogenic). Heavy metal pollution not only reduces the physical and chemical quality of the soil, reduces biological activity and biological availability of soil nutrients, but also poses a serious threat to human health and environmental security through entry into the food chain and penetration into groundwater which lead to the entry of these materials into the soil and its accumulation through irrigation with contaminated water and through atmospheric deposition. As well as their entry into the human food chain, double their risks. Therefore, industries can respond to society's expectations of responsibility and reduce concerns about human health through social and environmental initiatives.
Materials and Methods: A completely randomized experimental design was conducted in three replications and three depths (0-20, 20-40, and 40-60 cm) and three areas ( control (Hamaneh), semi-polluted (Khazarabad), and polluted (Shahneh)) in the west of Yazd. The fields in question were planted with pistachio, pomegranate, and walnut, respectively. All fields were irrigated by flooding. One kilogram of soil samples were collected from each field from three points and at each point of three depths, and a total of 27 samples were transferred to the laboratory. After preparing the samples according to the instructions for measuring heavy metals in soil, the total concentrations of heavy metals lead, cadmium, arsenic, nickel, selenium, mercury, beryllium, chromium, and thallium were measured at all three depths with an atomic spectrometer ,and then the land accumulation indices and enrichment factor were measured, and the data were statistically analyzed.
Results: The concentrations of mercury, beryllium, chromium, and thallium were not significant in any sample. In all three areas and at all three depths, lead and selenium contamination was within the permissible limits. Cadmium contamination was recorded only in the contaminated area of Shahneh, and arsenic and nickel contamination was recorded in the contaminated area of Shahneh and the semi-contaminated area of Khezrabad. The interaction effect of the level of contamination and soil depth was significant, and the 40-60 cm depth of the soil of Shahneh (contaminated) area had the highest concentrations of cadmium, lead, arsenic, nickel and selenium compared to Khezrabad (semi-contaminated) and Hamaneh (clean) areas. The concentrations of mercury, beryllium, chromium and thallium were not significant in any sample. The results showed that heavy metal contamination, especially in flood irrigation, has the ability to move in depth. Thus, in the contaminated area (Shehneh), with increasing depth, the cadmium concentration increased by 92.63% compared to the soil surface, the lead concentration increased by 44.48% compared to the soil surface, the arsenic concentration increased by 97.14% compared to the soil surface, the nickel concentration increased by 71.72% compared to the soil surface, and the selenium concentration increased by 91.75% compared to the soil surface. According to the two measured indicators, the concentrations of cadmium, lead, and selenium were in severe and dangerous conditions in all three regions. Arsenic was in a dangerous state in the Khezrabad and Shahneh areas, and nickel was only in the Shahneh area.
Conclusion: These results could be a warning sign that these pollutants may reach groundwater and canals. Also, following soil contamination, the absorption of these substances by plant roots increases, causing toxicity in the plant and subsequent entry into the food chain, which requires prevention of this process. The social responsibility of industries requires that any pollution they release into nature be minimal or in accordance with international standards and limits.
کلیدواژهها [English]
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