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PILOT SURVEY OF THREE SOIL HEAVY METALS AT ABANDONED INDUSTRIAL FARMLAND, AND DETERMINATION OF ITS POTENTIAL HEALTH RISK
M.K. Tsegay, Postgraduate Student
L.T. Sukhenko, Doctor of Biological Sciences, Associate Professor Astrakhan State University named after V.N. Tatishchev (Russia, Astrakhan)
DOI:10.24412/2500-1000-2023-10-1-23-30
Abstract. Food production near major consumer centers provides numerous economic benefits. However, there are numerous potential sources of contamination with hazardous substances, including heavy metals, in urban and industrial regions. Heavy metals adulteration in agricultural soil is an international issue. It is thought that fertilizers and atmospheric deposition together account for the majority of the trace element burden in farmed soils. Public concern over the possible buildup of heavy metals in agricultural soil has intensified because of the rapid development of various sectors, growth of urbanization, and increased discharge of agrochemicals into the environment. Heavy metal effects may imperil the natural processes of soil, directly or indirectly, via bioaccumulation and inclusion in the food chain. Metals accumulate in soil and living organisms' tissues because they are not vulnerable to metabolic degradation like the bulk of organic compounds. Normally, healthy plants can collect heavy metals in proportions that are harmful to human health if consumed; worsen the problem of heavy metal poisoning. The aim of this research is to assess the existence and concentration of selected heavy metals in a plot of garden site. The study tested the amounts of three specific heavy metals-copper (Cu), lead (Pb), and cadmium (Cd)- on a farming land, which about 24*104 m2 of topsoil from nine quadrats. According to the findings, the average values of Cd, Pb, and Cu were 2.02, 62.47, and 85.88 mg/kgcorrespondingly, and were over the standard allowed level except for Lead.
Keywords: heavy metal, soil, contamination, toxicity, atomic absorption spectrophotometer.
A significant non-renewable natural resource is agricultural soil. It may contain harmful HM elements like Cd, Pb, Cr, As, Hg, Cu, Ni, Zn, and a number of other elements because of both natural and anthropogenic processes. Agricultural soil has a significant impact on public health in both direct and indirect ways through the production of food, hence it is crucial to safeguard this resource and assure its sustainability. Public concern over the potential building of heavy metals in agricultural soil has intensified because of the rapid development of various sectors, the spread of urbanization, and the increased discharge of agrochemicals into the environment. Today, heavy metal agricultural soil pollution from industries like smelting, mining (metalliferous), pesticides, fertilizers, and equally from municipal dumps, etc. has spread to a global level and is posing both direct and indirect risks to public health through food production and the safety of
foods grown on farmland [17, 19]. As a result, it is vital to find, manage, and conserve this resource in order to insure its sustainabil-ity [10, 11].
Numerous substances are categorized as vital mineral nutrients for plant development and productivity. Cu, Zn, Fe, Mn, Mo, Ni, Mg, Ca, and B are a few examples. These elements can improve some cellular processes in plants, such as ion homeostasis, pigment biosynthesis, photosynthesis, respiration, enzyme activity, gene regulation, sugar metabolism, nitrogen fixation, etc., at relatively low concentrations. However, these same critical components can negatively affect plant growth, development, and reproduction when they are accumulated at concentrations over their optimal levels. Conversely, they also cause signs of mineral insufficiency in plants if the concentration falls below specific threshold values. A "heavy metal" is any metal that is usually dangerous or risky. Accord-
ing to William Azuka Iyama (2021) "heavy metals" are transition metals with defined high densities higher than 5 g/cm3 and harmful effects on ecosystems and living beings. The UN Environmental Program (UNEP) later investigated seven other heavy metals, including Cu, Sn, V, Cr, Mo, Co, and Ni, as well as three metalloids, Sb, As, and Se. Three heavy metals, Pb, Cd, and Hg, were first regarded the most harmful elements in the Global Monitoring Program authorized by the UN in 1973[16]. Today, there is increased focus on the presence of excessive amounts of heavy metals in agricultural goods [4]. After entering the food chain in the ecosystem through agricultural products, heavy metal toxicity complicates human health by affecting biological functions like the immunologi-cal, reproductive, and neurological systems, among others [3]. Although some heavy metals are considered micronutrients and should not be depleted, heavy metals are typically thought of as pollutants. Their buildup in soil may result in greater plant uptake and groundwater leaching.
The ability of food plants to collect metals and pass them to the next trophic level in the food chain is the main source of the health risk. Numerous food plants, crops, vegetables, fruits, etc., may hold extraordinarily high metal concentrations in their tissues without revealing dangerous effects [1].
The influence of organic matter amendments on heavy metal bioavailability is determined by the nature of the organic matter, its microbial degradability, salt content, and effects on soil pH and redox potential, as well as the soil type and metals involved. Heavy metal buildup in soil and plants can be modified by pH, organic matter content, heavy metal type or activity, plant species, soil type, climate, and other factors [5]. Because high-PH soil is electronegative, it can aid in both metal cation adsorptions to soil particles and heavy metal precipitation, which can alter how much heavy metal plants absorb [15, 18]. The majority of highland soils have soil organic matter levels between 1 and 6 percent of the topsoil bulk. The presence of organic matter in the soil combines with heavy metal ions to form organic complexes, which can
reduce heavy metal availability and mobility [8], but some research studies have found that some heavy metals exhibit increased activity as soil organic matter content increases [2, 13]. As a result, whether soil organic matter might boost heavy metal uptake by plants remains disputed [12, 14].
The area's intensive urbanization has resulted in unusually good agricultural soils, particularly for vegetable agriculture, becoming trapped within urban and suburban regions. Considering only agricultural soils, heavy metal buildup can have numerous effects, either directly harming natural soil processes or indirectly affecting the biosphere through bioaccumulation and inclusion in food [17].
Because heavy metal contamination in agricultural soil has a direct impact on the safety of food and public health, identifying and effectively controlling pollution sources in farmland is essential. Although household garbage, industrial effluent, and waste gas are significant sources of heavy metal pollutants in soil, there has been little research on how they can affect nearby agricultural land. The goal of this study is to evaluate three toxic heavy metals in the farmland soil of an abandoned factory and compare their concentrations to the maximum permissible limits for heavy metal-contaminated soil, thereby providing data to support future assessments of human health risks associated with HMP for future use of this farmland.
Materials and methods
Study Area: We carried out the research agricultural site at "Nachalo" district, Astrakhan, Russian Federation, in June 2022. The plot of land for the sampling area is shown in Figure 1, whose locations were determined using the google maps (GMS). The site has the following coordinates: 46°17'33.7"N 48°13'07.6"E .The research included about 225 m2 of topsoil and a total surface area of about 75,000 m2 plot of land .The study area was partly covered with herbaceous plants and partly bare. The area was also characterized by marked geomorphological heterogeneity, resulting in substantial pedological diversity: clay soils, salty soils, carbonated
shell-like soils, and irregular land shapes (fig. 1)
Materials: Soil, auger, 2 mm sieve, plastic bags, hand gloves, wipes marker, distilled water, deionized water, oven, aquaria, conical flask, filter papers, thermometer, pH meter, digital weighing balance, and atomic absorption spectrophotometer.
Collection of soil samples:
The three main kinds of soil sampling techniques are random, systematic, and stratified sample approaches. The simplest sampling approach is random sampling, when soil samples are randomly and stochastically gathered over the study location. It can serve as an efficient pilot research sampling program. This sampling method has a significant drawback in that soil samples could not be representative of the entire study location. Because of this, this sampling approach is typically used in generally homogeneous areas and is appropriate for investigations where the main goal is to ascertain whether soil heavy metal concentrations are raised above background levels or legal criteria [23].
According to the soil sample procedures, natural soil sampling was taken on farmland plot. Forty-five soil samples with varied soil depths were collected from nine soil sites for this experiment. For the detailed investigation, 30m*30m grid points were used for the preliminary soil exceedance zone, and 15 m*15 m grid points were used for the isolated exceedance locations and anomalous depths in the results. On agricultural land, soil Samples of soil were gathered randomly from a depth of 10-15 cm using the stainless-steel auger from nine locations (quadrats). Each soil sample was obtained by first collecting five sub-soil samples around each sampling quadrat, followed by thorough mixing of the samples to form the composite sample. The sample was then wrapped in a clean plastic bag and transported to the laboratory, Astrakhan State University, educational campus number 4 (Fig. 2). After oven drying (at 105 °C) for six hours, the soil samples were pulverized mechanically, passed through a 2 mm filter, and kept at temperatures below 4° C [6].
Figurel. Soil sampling future farmland area (sample)
Heavy metals Soil determination
Because of their profound impact on ecological quality, heavy metals are regarded as one of the primary contributors of environmental contamination. The main causes of heavy metal contamination in the environment are human activities, such as waste disposal, the burning of fossil fuels, mining, and wastewater discharges from manufacturing companies. High concentrations of heavy metals in sediments and soils have the potential to transfer to the aquatic environment, groundwater, and plants, as well as to animals and people, through transfer processes. There-
fore, among environmental studies, the use of straightforward and reliable methodologies for heavy metal monitoring is crucial. This method for determining the presence of heavy metals in soil was created to offer instructions on how to prepare sediment, sludge, and soil samples for atomic absorption spectrometry (AAS) examination.
To assess the total amount of heavy metals in the soil, soil sample was oven-dried at 70 °C for 48 hours. The material was crushed using mortar and pestle, a gram of the soil sample from each sampler was measured and deposited in a conical digestion flask. 10 ml
of strong nitric acid was added to the flask and the sample was maintained at 95 °C for 15 minutes without boiling. After cooling for 5 minutes at room temperature the sample was heated again at 95 °C for 30 minutes and then another 5 ml of concentrated HNO3 was added [7]. Up until no brown fumes were emitted, more intense HNO3 was added. The solution was allowed to evaporate until it was less than 5 ml in volume. After cooling, 3 ml of H2O2 and 2 ml of deionized water (DI)was added to the mixture, which was then heated below the boiling point until the effervescence diminished and 10 ml additional H2O2 was added until the effervescence stopped. This stage was continued for 2 hours at a temperature below the boiling point. The fluid was then allowed to evaporate until there was less than 5 ml left. After cooling, 10 ml of concentrated HCl was added, and the solution was heated at 95 °C for 15 minutes [9]. After cooling, the sample was filtered using WhatMan filter paper into a 50-ml volumetric flask, brought up to the mark with DI , and analyzed by AAS.
Result and Discussion Heavy metals in the soil An international problem is heavy metal poisoning of agricultural land. In addition to specific geogenic and climatic conditions, current environmental HM pollution appears to be mostly caused by situations like growing urbanization and rising industrial, municipal, agricultural, residential, and technical applications. However, the issue is more severe in many underdeveloped nations for the reasons listed above as well as probably because there is little knowledge about the hazardous effects of these elements on both agricultural and human health.
Comparing the element concentrations in the agricultural topsoil of the Nachalo district with the median value of element concentrations of soils worldwide[16] and the average element concentrations of the upper continental crust, the determined element concentrations are generally low (Table 1) and close to referent values.
This is particularly important because it pertains to agricultural topsoils inside or near a sizable urban area. Copper and cadmium are the two main trace metals that are deposited by immission from other sources as well as by cultivation techniques including adding fertilizer, both organic and artificial, using pesticides, using irrigation water, etc. [19]. Even if they are not initially present in substances provided to soil or plants in fatal quantities, critical levels of trace metals can be reached by applying them repeatedly. Agricultural topsoils differ in their element concentrations due to a variety of natural and synthetic variables.
Based on the results obtained, the order of average heavy metal concentration in the study region was Cu > Pb > Cd in natural settings. Moreover, the concentration of the target components varied along the different quadrants; this was presumably owing to the topography (relatively low or high level), soil organic and inorganic contents, moisture contents, or presence of plants on the farms. Such characteristics result in an unequal distribution of the target heavy metals since processes of mobility through the soil are quite diverse and significantly related to its physical-chemical nature, soil-water retention, fluid transmission, etc. For example, quadrats two, five, and six revealed considerably reduced Cu and Pb concentration than the rest of the quadrats (graph 1).
Table 1. Summary of heavy metal content in selected quadrats of study site (mg/kg-1).
Quadrats Heavy metals
Cd Cu Pb
1 2.76 106 98.8
2 1.1 45 21.28
3 3.59 104 117
4 4.32 128 89.33
5 0.63 40.04 11.75
6 2.83 40.43 12.4
7 1.51 99.38 89.01
8 0.27 87.1 42.75
9 1.21 123 80.39
Mean 2.02 85.88 62.47
Statistical analysis Max 4.32 128 117
Min 0.27 40.04 11.75
Std. 1.4 35.19 40.57
Table 2. Comparison of heavy metal concentration mean results with some heavy metal standards in soil
No Elements Mean results *Expected normal values **Intervention Values ***Permissible Value in plants ****Maximum Permissible addition (MPA)
1 Cd 2.02 0.80 12.00 0.02 00.76
2 Cu 85.88 36.00 190.00 10.00 3.50
3 Pb 62.47 85.00 530.00 2.00 55.00
*expected values specified to indicate desirable maximum levels of elements in unpolluted soils. * *Intervention when remedial action is necessary;
*** Permissible Value in plants Source: Denneman and Robberse 1990 and Ministry of Housing, Netherland 1994, WHO (1996). ****MPA maximal concentration exerting no significant influence on the growth and reproduction of the test organisms soil fauna (esp. Arthropods and earthworms), Dutch ecologists.
4 5 6
Sampling Quadrats Graph. 1.Concenteration of target elements against sampling quadrats
Cadmium, Cd
The research area was historically an industrial location; therefore, the presence of heavy metals was unavoidable. Generally, cadmium exists and stays in the environment because of anthropogenic actions that are not
simply restricted to metal ore burning and incineration. In comparison to the usually accepted value (2.02. > 0.8) and MPA, 0.76, the average Cd contents in the topsoil of the agricultural (study area) were normally high. Additionally, the research found that 88.89% of
sample values were above the flame AAS detection limit (0.5 mg kg-1). Quadrat 4 had the highest concentration of Cd, whereas quadrat 6 had the lowest value. As a result, Cd pollution on the intended farms could be problematic. In such urban environment, Cd emissions may come from a variety of sources, including coal burning, vehicle traffic, and tire wear and tear. The city officials can reduce the future health impact of poor air quality by monitoring it at the emission station.
Lead, Pb
Many people perished because of lead poisoning brought on by mining dust and contaminated soil. Pb exposure causes long-term harm in both adults and pregnant women, raising their risk of high blood pressure and congenital abnormalities, respectively. The planned farmland's topsoil had an average lead concentration of 62.47 mg kg-1, which is lower than the general standard value for natural soils and much lower than the remediation intervention threshold (530 mg kg-1). However, 44.44% of the research area's quadrats had lead concentrations that are greater than the general standard norm for natural soils, so still there will be a chance of lead poisoning. Although it often only affects the top few centimeters of the soil surface, airborne deposition of lead is thought to be the principal cause of its emission. Strong Pb2+ adsorption in organic and colloidal clays as well as the formation of insoluble lead che-lates with organic matter are the two factors responsible for this retention in the upper half of the profile.
Copper, Cu
Although copper is a trace element important for human cells, too much can harm mitochondria and other cell membranes. Toxic copper levels can cause mortality, liver damage, and coma. The average copper concentration in the examined area is 85.8 mg kg-1. Most European countries utilize standard values of 60-100 mg kg-1. There are no visible marks in the inspected region. Cu buildup was determined in agricultural topsoil from urban emitters or from pesticide application. Copper, on the other hand, is characterized by point sources of contamination, mainly uncontrolled, active, or untended trash
dumps. Such locations pose significant pollution threats to both soil and groundwater. The average copper concentration was is greater than Maximum Permissible addition (MPA and normal natural soil values. However, it is still far smaller than the intervention value for remediation urgency.
Conclusions
Environmental contaminants include heavy metals and metalloids (HMs). They are also agricultural soil pollutants since HMs have the potential to harm crop health and productivity if they are present in the soil at high concentrations. HMs are resistant to degradation, and if they are not absorbed by plants or eliminated through leaching, they can build up in the soil and last a very long time. Cd, Pb, Cr, As, Hg, Ni, Cu, and Zn are among the elements that are regularly discovered to pollute agricultural soils and have hazardous effects on plants at high concentrations. They include the very toxic elements Cd, Pb, As, Hg, and Cr, which are harmful to plant health at practically all levels of exposure.
It is vital to conserve, manage, and sustain this resource since agricultural soil has both direct and indirect effects on public health through the production of food. The public is becoming increasingly concerned about the potential buildup of heavy metals in agricultural soil because of the industry's speedy development and the increase of pesticide release into the environment. These farmlands put both human and environmental health in peril due to the accumulation of heavy metals. According to the pilot survey, using farmland without adopting any protective measures could result in health concerns from a few heavy metals (Cd, Cu, and Pb). The food plants that grow on this farmland for eating may facilitate the passage of hazardous contaminants into the human body. Governments should encourage coordinated data collecting, research, law, and regulation, as well as the usage of indicators. Regular environmental monitoring and repair are therefore important to ensure that soils used for agricultural are not contaminated by heavy metals.
Acknowledgement
We thanks to Andrey Tryasuchev for his department) for their transportation and labor atomic absorption spectrophotometer skills, assistance. as well as Astrakhan State University (soil
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ПИЛОТНОЕ ИССЛЕДОВАНИЕ ТРЕХ ТЯЖЕЛЫХ МЕТАЛЛОВ В ПОЧВЕ ЗАБРОШЕННЫХ ПРОМЫШЛЕННЫХ ЗЕМЕЛЬ И ОПРЕДЕЛЕНИЕ ЕГО ПОТЕНЦИАЛЬНОГО РИСКА ДЛЯ ЗДОРОВЬЯ
М.К. Тсегай, аспирант
Л.Т. Сухенко, д-р биол. наук, доцент
Астраханский государственный университет имени В.Н. Татищев (Россия, г. Астрахань)
Аннотация. Производство продуктов питания вблизи крупных потребительских центров дает многочисленные экономические выгоды. Однако в городских и промышленных регионах существуют многочисленные потенциальные источники загрязнения опасными веществами, в том числе тяжелыми металлами. Фальсификация тяжелых металлов в сельскохозяйственных почвах является международной проблемой. Считается, что удобрения и атмосферные выпадения вместе составляют большую часть содержания микроэлементов в обрабатываемых почвах. Обеспокоенность общественности по поводу возможного накопления тяжелых металлов в сельскохозяйственных почвах усилилась из-за быстрого развития различных отраслей, роста урбанизации и увеличения выбросов агро-химикатов в окружающую среду. Воздействие тяжелых металлов может прямо или косвенно поставить под угрозу естественные процессы в почве посредством биоаккумуляции и включения в пищевую цепь. Металлы накапливаются в почве и тканях живых организмов, поскольку они не подвержены метаболическому разложению, как основная часть органических соединений. Обычно здоровые растения могут собирать тяжелые металлы в пропорциях, вредных для здоровья человека при употреблении в пищу; усугубляют проблему отравления тяжелыми металлами. Целью исследования является оценка наличия и концентрации отдельных тяжелых металлов на участке садового участка. В ходе исследования было проверено количество трех конкретных тяжелых металлов - меди (Си), свинца (РЬ) и кадмия (Cd) - на сельскохозяйственной земле, площадь которой составляет около 24*104 м2 верхнего слоя почвы из девяти квадратов. Согласно полученным данным, средние значения Cd, РЬ и Си составили 2,02, 62,47 и 85,88 мг/кг-1 соответственно и превышали нормативно-допустимый уровень, за исключением свинца.
Ключевые слова: тяжелый металл, почва, загрязнение, токсичность, атомно-абсорбционный спектрофотометр.
