## 1 Introduction  
Soil is the foundation of food production systems and is a critical component for national food security. Soil quality has become a key concern internationally due to competing demands between people, resources, and the environment [1, 2, 3, 4, 5, 6, 7]. Specifically, the potentially toxic elements (PTEs) such as arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), lead (Pb), copper (Cu), nickel (Ni), and zinc (Zn) in soil have received significant attention in the past few decades due to their widespread distribution and severe toxicity to plants, animals, and humans. Oral ingestion (such as unintentional/intentional hand-oral ingestion), respiratory inhalation (as dust via respiratory inhalation), and dermal contact are the main routes through which PTEs from soil can be transferred into the human body [8, 9, 10, 11, 12, 13]. Excessive intake or long-term exposure to PTEs may cause adverse effects to human beings, example of which being that As is a recognized human carcinogen that has been linked to an increased risk of adverse health effects in children, including cognitive impairment [14; 15; 16; 17; 18]. Excessive Cd content increases the risks of postmenopausal breast cancer and upper gastrointestinal cancer, as well as kidney and bone damage [19]. Children experience higher non-carcinogenic health risks caused by Pb through ingestion when compared to adults [20]. Long-term exposure to low concentrations of Pb may damage a child's brain during development and may result in neurological issues [21]. Hg may be found in a variety of forms, including in their metallic, elemental, inorganic, and organic forms in the environment [22]. Exposure to high levels of methyl mercury during the second trimester of pregnancy might damage the fetus' neurological system and may cause issues with language, attention, and memory [23; 24; 25]. Despite the fact that Cu, Cr, Zn, and Ni are essential trace elements for human health, chronic and excessive intake may lead to damaging effects on human beings [26]. When Cr, Cu, Zn, and Ni levels reach their acceptable threshold values, they can induce non-carcinogenic risks, such as neurologic involvement, headaches, liver and renal illness, and skin and respiratory system lesions [27; 28; 29; 30]. The side effects of excessive Ni consumption and exposure include contact dermatitis, cardiovascular illness, asthma, lung fibrosis, and respiratory tract cancer [31]. Soil plays a crucial role in the biogeochemical transformation of the top layer of the lithosphere [32]. PTEs enter the soil system in a variety of ways, both naturally and anthropogenically. Naturally, PTE soil contamination occurs as a result of the weathering process of parent materials that contain significant levels of PTEs [32; 33; 34; 35; 36; 37; 2, 37]. Anthropogenically, the soil has been contaminated by fast industrial expansion and subsequent effluent discharge or exhaust emissions, agricultural fertilizers and pesticides, mining operations, population explosions, and subsequent urban dwelling pollution [6; 38; 39; 40; 41; 42; 43; 44; 45]. Anthropogenic activities are generally regarded as being the primary source of PTEs in the soil in highly developed, urbanized and industrial urban areas [46; 47; 48; 49], mining areas [5; 50; 51; 52], or agricultural sectors [41; 53]. However, a large body of research on this subject supports the importance of the geological background in contributing to higher PTE contents in soil [33; 34; 35; 36; 37; 2; 38; 39; 54; 55]. The PTE levels in soil are frequently elevated due to mineral resources (such as Cu, Pb, Zn, and Hg), as well as carbonate and basalt parent materials [56; 57; 58; 59; 60; 61; 62; 63]. This phenomenon can be observed in the soils of the Baoshan area in Yunnan province, southwest China, where mineral resources and carbonate and basalt parent materials are widely distributed [54; 55; 64].