## 3 Results and Discussions
### XRF Soil Analysis
Human activities have doubled its concentration, and emissions are predicted to increase by 5% each year [67]. The earth's upper crust contains approximately 0.05 mg kg\({}^{-1}\) of Hg, the middle crust has about 0.0079 mg kg\({}^{-1}\) and the lower crust contains 0.014 mg kg\({}^{-1}\)[69]. Elemental Hg vapor is present in the atmosphere, where it can be retained and transported over long distances. It has a residence time of 0.5 to 1.5 years, while other oxidized species have much shorter lifetimes, lasting only hours or days, leading to rapid deposition and localized impacts. In soil, water, and sediments, mercury is primarily found in its inorganic form, Hg (II), while in biota, the dominant form is (mono)methylmercury (MeHg; CH\({}^{3}\)Hg+) [70; 71]. Natural sources of Hg include volcanic activity, weathering of mercury-containingores, vegetation fires and evaporation from soils and water, particularly from ocean water, which contributes approximately 2.68 \(\times\) 10\({}^{6}\) tons of Hg per year [70; 72; 73]. Anthropogenic sources are responsible for two-thirds of the total release of Hg. The primary human-related sources include coal combustion, municipal solid waste incineration, various thermochemical conversion processes, pharmaceutical industries, medical compounds, dentistry, scientific instruments, the paint and paper industry, ceramic and cement production, pesticides, antiseptics, artisanal small-scale gold mining where Hg is used in refining gold and silver, mercury mining and the chlor-alkali industry [71; 72; 73; 74; 75]. Over the past decades, growing awareness of mercury's harmful effects has led to various regulatory measures. One significant initiative is the Minamata Convention on Mercury, held in Geneva, Switzerland, on 19 January 2013. This convention required the development of strategies to identify and assess Hg-contaminated sites to protect human health and the environment from the adverse effects of mercury [75; 76]. Mercury holds a unique and significant place among environmental pollutants, as its severe health effects have been clearly demonstrated in several tragic poisoning incidents. Notably, in Japan in 1953, an epidemic of mercury poisoning occurred in villages around Minamata Bay due to the consumption of contaminated fish. A similar incident took place along the Agano River in Niigata, Japan, between 1964 and 1965, and in rural Iraq from 1971 to 1972, where mercury-based fungicide-treated grain led to widespread poisoning [70]. Fish consumption is considered the primary pathway for exposure to methylmercury (MeHg). According to the United States Environmental Protection Agency (USEPA), mercury ranks among the top three most potent toxic agents that can occur naturally or be introduced through various human activities. The World Health Organization (WHO) designates mercury as one of the ten most dangerous substances to public health. In conclusion, mercury can exist in toxic forms such as organic, inorganic, and metallic compounds, each with distinct properties related to solubility, volatility, mobility, toxicity and bioavailability. Due to its high volatility, elemental mercury from soil can enter the atmosphere, posing significant environmental threats. Mercury is a highly mobile pollutant, toxic to humans and wildlife even at extremely low concentrations [67; 70; 74; 75]. For PS sites (Figure A6, Appendix A), the minimum concentration of Hg was 0.8 mg kg\({}^{-1}\) (observed at locations 9), while the maximum concentration was 1.2 mg/kg (observed at locations 5). Hg presented for ESs a minimum concentration of 0.9 mg kg\({}^{-1}\) for location 6 and a maximum of 1.1 mg kg\({}^{-1}\) for locations 5 and 7. All Hg values exceeded the normal value (NV) specified in Romanian legislation [52], and at PS locations 2, 3, 4, 5, 6, 7 and 10, as well as ES locations 4, 5, 7, 8, 9 and 10, the SIT limit was also exceeded. Silver (Ag) values ranged between 2.80 and 3.70 mg kg\({}^{-1}\), with an average of 3.38 mg kg\({}^{-1}\).