pXRF method development for elemental analysis of archaeological soil

Abstract

Portable X‐ray fluorescence (pXRF) is now widely used for detecting the elemental composition of a material. Elemental analysis can enhance archaeological interpretations, such as mapping, preservation analysis and identifying anthropogenic activities. However, validated and reproducible protocols for analysing archaeological soil are still required. The elemental concentrations detected with three sets of preparation methods were compared: in‐situ (no preparation), in‐field (analysing through plastic bags) and ex‐situ analysis (laboratory‐based preparation). Influential factors were also investigated: calibration parameter, moisture, homogeneity, sieve size and soil type. In‐field analysis attempted to improve reliability without offsite processing, but instead substantially reduced elemental concentrations and skewed the proportional distributions. Ex‐situ analysis significantly increased elemental concentrations and reduced variation. Proportional distribution was different between the three methods, but unchanged following homogenizing and sieving. These comparisons demonstrated that ex‐situ analysis maximizes detection and ensures consistent samples.

Unique chemical parameters and microbial activity lead to increased archaeological preservation at the Roman frontier site of Vindolanda, UK

“…Soils were analysed following the method provided by Williams 42 . The dried soil samples were homogenised with mortar and pestle for 140 s and sieved to 2 mm.…”

Identifying anthropogenic features at Seoke (Botswana) using pXRF: Expanding the record of southern African Stone Walled Sites

“…Moreover, low-Z elements such as for example Mg, S and Si, may present errors in detection as the pXRF does not generate a full vacuum and therefore air interferes with the quantification of such elements [49]. Due to its novelty as research tool in archaeology, voices for the elaboration of reliable systematic protocol to be readily applied by archaeologists have been repeatedly raised [70][71][72][73]. Our work presents a further case study on archaeological sediments and proposes the use of kriging as a method to map the results.…”

A Combined Application of Molecular Microbial Ecology and Elemental Analyses Can Advance the Understanding of Decomposition Dynamics

“…To quantify the content for phosphorus, potassium, iron, calcium, magnesium and sulphur (Hopkins et al, 2000;Carter and Tibbett, 2006;Elfstrand et al, 2007;Benninger et al, 2008), soil samples were dried overnight at 105 • C, ground with a mortar and pestle, sieved to 2 mm and homogenised. XRF cups (31 mm) were filled with ∼8 g of homogenised soil from each individual treatment and covered with 5 µm polypropylene film (Williams et al, 2020) before scanning at 30 s low and 60 s light beam using mining mode. Blank and standard samples were run after every 10 samples analysed.…”