## 1 Introduction  
One of the world's largest and last mercury mines is located in Khaidarkan, Batken Province, Kyrygzstan. Medecins sans Frontiares (MSF, Doctors without Borders) and the Kyrygz Ministry of Health (MOH) have found that the Batken Province has elevated levels of non-communicable diseases (NCD), confirming the findings of local physicians [1]. MOH, MSF, and TerraGraphics International Foundation (TIFO) partnered to assess environmental factors that may contribute to elevated NCD rates, using the Human HealthRisk Assessment (HHRA). As part of the project, a goal is to provide the Kadamjay Rayon laboratory the ability to efficiently and cost-effectively screen areas for potentially harmful mercury concentrations. This research aims to develop a methodology using an X-ray fluorescence spectrometer (XRF) to characterize heavy metal exposure risks and meet this goal.  
Mercury is ubiquitously used in artisanal and small-scale gold mining (ASGM) [2]. Mercury is added to ore where it forms a stable amalgam with gold, allowing miners to isolate gold from other minerals [2]. An estimated 37% of global mercury emissions are due to ASGM, accounting for 410 to 1400 tons of mercury released into the atmosphere [2]. ASGM has increased dramatically in recent years with the steep rise in gold prices, which reached 1800 USD per ounce as of January 2022 [2; 3]. ASGM is an important source of income, in impoverished areas where other income sources are not available [2]. Simultaneously, these communities face multiple social and health challenges, including higher rates of NCD [2]. This research also aims to develop a rapid, cost-effective, and easily implemented methodology to identify harmful Hg concentrations in communities with limited resources.  
XRF technology has been proven to be an accurate mechanism for determining concentrations of various heavy metals [4]. According to the United States Environmental Protection Agency (USEPA), a portable XRF can successfully measure Hg, with detection limits typically ranging from 10-20 milligram per kg [4]. Other studies have found Hg detection limits of 7.4 mg/kg or less than 5 mg/kg [5; 6]. Some studies have found that XRF has a poor correlation with Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) for measuring Hg [7]. When compared to Cold Vapor Atomic Absorption (CVAA), studies have found variable correlations for XRF analysis of Hg [4; 5; 8]. However, the unreliable correlation is believed to be caused by soil samples' heterogeneity and mercury beads within the samples in that particular study [5]. Good correlations between XRF and CVAA methods have been found while accurately measuring 93% of soil samples in one study [5]. No studies were found in the scientific literature comparing XRF to Atomic Absorption Spectrometry (AAS) for Hg in soil. Studies comparing XRF and AAS for Hg in other medias found good correlations between the two methods [9; 10]. Additionally, correlations have been found for other heavy metals in soil [10; 11; 12; 13].  
This study develops a relationship between XRF and an AAS with a Pyrolyzer attachment for Hg. A Hg site-specific conversion factor was successfully found for ex situ-bulk and ex situ-sieved soil samples. Although a conversion factor could not be established for in situ soil samples, it was determined that XRF could still be used for qualitative measurements of in situ soil. The Kadamjay Sanitary and Hygienic Laboratory (SHL) will use XRF as a screening tool to identify potentially harmful mercury concentrations in soil. With the ability to screen areas quickly and inexpensively for mercury contamination, SHL will be able to prevent or reduce mercury exposures and associated adverse health effects.