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Emergence of portable X-ray fluorescence (pXRF) systems presents new opportunities for rapid, low-cost plant analysis, both as a lab system and in situ system. Numerous studies have extolled the virtues of using pXRF for a wide range of plant applications, however, for many such applications, there is need for further assessment with regards to analytical parameters for plant analysis. While pXRF is a potential powerful research tool for elemental composition analysis, its successful use in plant analysis is made more likely by having an understanding of X-ray physics, calibration process, and ability to test a variety of homogenous and well-characterized materials for developing a matrix-specific calibration. Because potential pXRF users may often underestimate the complexity of proper analysis, this study aims at providing a technical background for plant analysis using pXRF. The focus is on elemental quantification under different analytical parameters and different methods of sample presentation: direct surface contact under vacuum, placement in a sample cup with prolene as a seal, and without the aid of a vacuum. Direct analysis on the surface of a pXRF provided highest sensitivity and accuracy (R 2 > 0.90) for light elements (Mg to P). Sulfur, K, and Ca can be reliably measured without the aid of a vacuum (R 2 > 0.99, 0.97, and 0.93 respectively), although lower detection limits may be compromised. pXRF instruments provide plant data of sufficient accuracy for many applications and will reduce the overall time and budget compared with the use of conventional techniques. Sensitivity and accuracy are dependent on the instrument's settings, make, and model. © 2015 The Authors. X-Ray Spectrometry published by John Wiley & Sons, Ltd.Additional supporting information may found in the online version of this article at publisher's web site. IntroductionKey plant nutrients, including potassium (K), phosphorus (P), and sulfur (S), play important roles in regulating processes such as photosynthesis, carbon respiration, and tissue building. Elemental analysis of plants is critical to plant studies and agriculture. However, despite the routine application of digestion-based analytical techniques in many laboratories, the slow and often hazardous sample digestion process can present a challenge in the analyses of plant nutrients, particularly where hundreds or even thousands of samples are to be analysed.[1] The conventional plant elemental analyses based on plant extracts are cumbersome and of variable accuracy and present major limitations to exploiting the full potential of plant nutrient analysis. An ideal system for analysis would include accuracy, replicability, portability, and minimal sample preparation. The technology that currently provides the best option to meet these needs is energy-dispersive X-ray fluorescence (ED-XRF), particularly in the form of a portable instrument portable X-ray fluorescence (pXRF). These instruments are commonly used for scrap metal sourcing, [2] geochemical provenience of obsidian,...

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Despite increasing interest in the relationship between culture transformation and abrupt climate change, their complexities are poorly understood. The local impact of global environmental fluctuations depends on multiple factors, and their effects on societal collapse are often assumed rather than demonstrated. One of the major changes in west European later prehistory was the Copper to Bronze Age transition in the early second millennium BC, contemporaneous with the 4.2 ky cal. BP event. This article offers a multi-dimensional insight into this historical process in the Iberian Peninsula from a multi-proxy and comparative perspective. Three study areas, representative of diverse ecological settings and historical trajectories, are compared. Using radiocarbon dates, 13 C discrimination (Δ 13 C) values on C3 plants, and high-resolution palynological records as