1. Introduction
One of the most serious environmental issues facing the world today is soil contamination. The toxic contaminants in soil spread to other parts of the ecosystem and pose a direct or indirect threat to human health [
1,
2]. Industrial emissions, illegal dumping, municipal disposal of wastes, and the improper use of agrochemicals collectively contribute to the concentration and absorption of heavy toxic metals in the environment [
3,
4,
5]. Severe heavy metal accumulation in the soil surface will degrade the soil ecosystems and raise the possible exposure and significant risk of heavy metals to humans [
6]. Toxic metal contamination has been linked to serious health consequences in humans, including cardiac diseases, skeletal illnesses, infertility as well as neurological disorders [
2,
7]. Some elements, like Cd, Hg, Cu, and As, etc., are poisonous and harmful to people, even at low concentrations [
8,
9]. These metals concentrate in adipose tissues, bones, muscles, and joints after entering the body, causing a variety of disorders [
10,
11].
The technique for estimating the injury or damage from a possible health threat is referred to as risk assessment. In general, risk assessment is a scientific framework for environmental policy [
2]. The overall purpose of risk evaluation is to assess the environmental impact of contamination in water, air, soil, or sediment [
12]. Several studies have been conducted across the world to examine the potential ecological risk of heavy metals. Rostami et al. [
2] studied the concentrations of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn, and As) in agricultural soils in the Kamfiruz district of Fras in Iran and assessed their ecological risk. The findings revealed that Cd was the main contaminant, which might be attributable to human activities such as the use of chemical fertilizers and pesticides in the sampling area. Qi et al. [
9] investigated the levels of heavy metal contaminations (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and ecological risks in agricultural soil in Shanxi Province, China. A total of 33 surface soil samples were collected from 11 cities in Shanxi. The soil-heavy metals pollution levels were evaluated using a geo-accumulation index, and their ecological risks were assessed using respective risk indices. This study found that the metals Cd and Hg were present in higher concentrations and posed higher ecological concerns in agricultural soil in Shanxi. The conclusions of this study will give fundamental information on agricultural soil pollution management and control. Tisha et al. [
13] performed a study in Savar tannery industrial estate, Bangladesh to assess the concentrations of heavy metals, such as Cd, Cr, Pb, Cu, and Ni, in the surface soils and to evaluate the level of contamination and ecological risks. This study concluded that continuous heavy metal contamination monitoring should be conducted to estimate the risk of heavy metal contamination in the soil.
The multivariate statistical technique, along with a variety of indices, provides a modern framework for assessing toxic metal contamination in field soils that may also be used in similar soil pollution systems. In the present study, toxic metals in the soil were chosen as they cause public health concerns and influence the ecological balance. This study aims to: (i) determine the concentrations of toxic metals including arsenic (As), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in the surface soil, (ii) evaluate the status of contamination by using the contamination factor (Cf), (iii) assess the ecological risk factor (Er), and (iv) evaluate the potential ecological risks and spatial distributions of target toxic metals in the soil of the study area.
2. Study Area
Soil samples were collected from the fields close to an abandoned mining area surrounded by non-cultivated farmland in Cerrito Blanco, Matehuala municipality, San Luis Potosi, Mexico. It has a total geographical area of around 4.84 hectares and is positioned within 23°40′30″ N latitude and 100°35′27″ W longitude (
Figure 1). The study area is the Joya Verde soccer sports club, which comprises irrigated lands, including three half-hectare soccer grounds, and vegetative areas, known as non-irrigated lands, surrounding the soccer pitches [
14]. Massive amounts of recent as well as historical tailings are reported to have been deposited on the surrounding terrains as a result of mining activities on an unmanaged privately owned land with no restrictions on public access [
15,
16,
17]. Slags, wastes, and construction debris from a dormant metal ore smelter that operated within Matehuala City until the 1960s have accumulated on the site and further contaminated the environment [
17,
18]. The area has a semi-arid climate, and the predominant vegetation is michrophyllus scrub that is mixed with agricultural lands and susceptible to mild cattle grazing [
19]. The types of soil in this area include Calcisol and Gypsisol, and the area receives limited precipitation, ranging from 300 to 500 mm per year [
20,
21].
5. Conclusions
The toxic metal contamination and accumulation in soils can result in a variety of issues for the environment, plants, and humans. In this study, the sources, as well as the status of contamination, were identified by the Cf and Er of five different toxic metals in the Joya Verde soccer sports club’s surface soils. The primary metal contaminants were arsenic (As) and zinc (Zn), with amounts in most of the soil samples above the toxic metal background reference value. The Cf values revealed that the soil had a low range of contamination with Cu, Ni, Pb, a low to moderate range of contamination with Zn, and an extreme level of contamination with As. Additionally, Er demonstrated that the soil had a low risk of contamination with Cu, Ni, Pb, and Zn, but a very high risk of contamination with As. Based on PCA, the factors influencing toxic metal accumulation varied across the sampling locations. According to the level of potential ecological risk index (RI), arsenic poses the highest risk out of toxic metals, while the other metals have a low risk level. In comparison to the study location, the surrounding areas with intensive industrial operations, past mining activities, and the growth of urban populations were often characterized by a moderate and considerable potential ecological risk. The outcomes of this work provide better knowledge of toxic metal enrichment and the risk of soil used for sports purposes, which is a significant issue for human health.