Analysis of Heavy Metals and Other Elements in Soil Samples for its Physicochemical Parameters Using Energy Dispersive X-Ray Fluorescence (EDXRF) Techniques

Research Article

Austin J Environ Toxico. 2023; 9(1): 1045.

Analysis of Heavy Metals and Other Elements in Soil Samples for its Physicochemical Parameters Using Energy Dispersive X-Ray Fluorescence (EDXRF) Techniques

Shirin Akter*; Jolly YN; Kabir MJ; Mamun KM

Atmospheric and Environmental Chemistry Laboratory, Atomic Energy Centre, Bangladesh

*Corresponding author: Shirin Akter Atmospheric and Environmental Chemistry Laboratory, Atomic Energy Centre, Dhaka, PO Box 164, Dhaka-1000, Bangladesh. Email: [email protected]

Received: September 19, 2023 Accepted: November 04, 2023 Published: November 11, 2023

Abstract

The present study was conducted to determine the physicochemical properties and the composition of trace elements of soil samples in agriculture lands. This study has been designed to analyze heavy metal contaminations in 12 soil samples collected at a depth 0-20 cm from the agriculture areas of Munshiganj using Energy Dispersive X-Ray Fluorescence (EDXRF) spectroscopy. This study revealed that the maximum Ca, Ti, Mn, Fe, Cu, Zn, Rb, Sr, and Pb contents in soil samples were 76293, 3911, 534, 44652, 57.50, 532, 101.45, 242.11 and 39.31 mg/ kg respectively. A physicochemical study of soil is based on various parameters like soil PH, electrical conductivity (EC), TDS mg/L, Salinity. The value of soil PH found to be 7.53 to 9.24, conductivity was ranging from 22.4-66.5 μs, Total Dissolved Solid (TDS) was ranging from 13.39-37.70mg/L and salinity was ranging 22.40-66.50 μs. Along with the experimental data, several environmental indices (Contamination factor, geo-accumulation index, enrichment factor, pollution load index, Quantification of Anthropogenic Concentration of Metal (QoC) have been identified for comprehensive assessment of our study site, which suggesting that these heavy metals Ca, Ti, Mn, Fe, Cu, Zn, Rb, Sr, and Pb might come in the samples due to anthropogenic activities.

Keywords: EDXRF; Heavy metal; Physico-chemical parameter; Pollution degree

Introduction

Bangladesh is a developing country which is largely depended on its modernization and enhanced industrial activities in many ways. As a result, it leads to the increased use of different fossil fuel in a large scale. This gives rise to air pollution in the city. So, concern about atmospheric particulate pollution in urban region is receiving growing importance worldwide [1]. The effect of soil contamination depends on soil properties since this control the mobility, bioavailability and residence time of contaminants [2]. The main anthropogenic sources of heavy metals are industrials areas, mine tailings, disposal of high metal wastes, leaded gasoline and paints, application of fertilizers, animal manures, sewage sludge, pesticides, waste water irrigation, coal combustion residues and atmospheric deposition from varied sources [3]. Industrialization, wars, mining and intensification in agriculture have aleft a legacy of contaminated soils around the world [4-8]. Since urban expansion, soil has been used as a sink for dumping solid and liquid wastes. It was considered that once buried and out of sight, the contaminants would not pose any risk to human health or the environment and that they would somehow disappear [9]. The main sources of soil pollution are anthropogenic, resulting in the accumulation of contaminants in soils that may reach levels of concern [10].

Heavy metals are the most persistent and complex kind of pollutants to remediate in nature. They not only degrade the quality of the atmosphere, water bodies, and food crops, but also threaten the health and well-being of animals and human beings. Metals accumulate in the tissues of living organisms because unlike most organic compounds they are not subject to metabolic breakdown. Among the heavy metals Zn, Ni, Co and Cu are relatively more toxic to plants and As, Cd, Pb, Cr and Hg are relatively more toxic to higher animals [11].

The soil profile refers to a vertical section of the soil down to and including the geological parent material. The nature of the profile is important in many aspects; plant growth including root development, moisture storage and nutrient supply. The profile is, therefore, the basic unit of study in assessing the true character of a soil. It usually displays a succession of layers that may differ in properties such as color, texture, structure, consistence, porosity, chemical constitution, organic matter content and biological composition. These layers, known as soil horizons, occur approximately parallel to the land surface. Each one of these layers has a designation called genetic horizons which express a qualitative judgement about development of the soil over time. Agricultural land and vegetables in sewage-irrigated areas were also found to be heavy metal and metalloid contaminated. Heavy metals are important from the viewpoint of their toxicity and essentiality and have been widely studied for their toxic effects and bio-accumulation in food chains. In addition to their essentiality for human nutrition, some micronutrients (e.g., Cu, Cr, and Ni) might be toxic at elevated concentrations [12]. Such activities have great impact on the ecology and agriculture as well as health and safety effects.

Materials and Methods

Study Area

Munshiganj Sadar is an upazila of Munshiganj District in the Division of Dhaka, Bangladesh. It is a part of the Dhaka Division and borders Dhaka District. Total land area is 235974 acres (954 km2), out of which 138472 acres (560 km2) are cultivable and 5609 acres (23 km2) are fallow land. 40277 acres (163 km2) of land is irrigated while 26242 acres (106 km2) of land is under river. It has 14 rivers of 155 km passing through. In this study samples were collected from Munshiganj are below:

Preparation of Soil Samples

The soil samples after collection were sieved with a stainless-steel sieve to remove dirt. All samples were then taken into porcelain dishes separately. Each dish with the particular sample was placed in an oven at around 70 °C until a constant weight was obtained. The dried mass of each sample was then pulverized to fine powder using a mortar and pestle, and preserved in a plastic vial with the identification mark inside a desiccator. Finally, the homogeneous powder was used to prepare pellet (7 mm dia. and 1mm thick using 10-ton pressure by a pellet maker (Specac, UK) for elemental analysis by Energy Dispersive X-Ray Fluorescence (ED-XRF).

Sample Irradiation and Method Validation

The experiments and sample irradiation have been done using EDXRF Spectroscopy System. The X-Ray beam of 22.4 keV from 109Cd annular excitation source hits the target sample and the characteristic X-rays are produced. The [Si (Li)] detector (Canberra) having the resolution of 175 eV at 5.9 keV has been applied for the detection of characteristic X-rays. These detected X-Rays are converted into voltage pulses and amplified by the spectroscopy amplifier and processed in MCA having16K+channel. The energy resolution of a Si (Li) spectrometer system is a function of both the electronic noise and of fundamental statistical variations in the number of charge carriers produced within the intrinsic region for a given photon energy.

The irradiation and spectrum data acquisition are operated and controlled by a software package provided with the system. The standard materials were also irradiated under similar experimental conditions for construction of the calibration curves for quantitative elemental determination in the respective samples. The commercial software AXIL has been applied for the qualitative and quantitative elemental analysis.

Concentration Calibration

A direct comparison method based on EDXRF technique was used for elemental concentration measurement [13]. The energy of the peaks is indicated with the position of the x-axis and the relative intensities are represented by the length of the indicator line in y direction. That some lines are split although there is only one peak visible. The programme does separate between the K-A1 and K-A2 lines. After selecting the appropriate type of calibration curve. As the analysis is based on direct comparison the standards of similar matrices were used to construct the calibration curve in order to avoid any matrix effect. Three soil standards (Soil-7 /IAEA, Montana-1/2710a, Montana-2/2711a) were used for the construction of calibration curves for carrying out elemental analysis in soil. The calibration curve for each element was constructed based on the K X-ray intensities calculated for the respective elements present in standard samples. The curves were constructed by plotting the sensitivities of the elements as a function of their atomic number. The validation of the calibration curve constructed for elements present in the standards was checked through analysis of standard reference materials (Montana-1). The results obtained for elements of interest and certified values for corresponding elements are shown in the Table 2. All results in respect to certified known values were found to vary within the acceptable range of error.