Portable X-ray Fluorescence Spectrometry Research Articles

Multi-analytical Study on the Tara Thangka at Daxingshan Temple in Xi'an, Shaanxi, China

ABSTRACT In this study, a Tara thangka (from a complete set of 21) dating to the mid-Qing Dynasty (1776–1839 CE) at Daxingshan Temple in Xi'an, Shaanxi, China was analyzed using various techniques, including portable X-ray fluorescence spectroscopy (p-XRF), Raman spectroscopy (RS), Fourier transform infrared spectroscopy (FTIR), optical microscopy (OM), and mass spectrometry-based proteomics. Through a multi-analytical methodology, in situ non-invasive testing was complemented with an analysis of a limited number of samples. By complementary evidence derived from the above analyses, it can be determined that the thangka was painted on a hemp substrate, with common colorants such as cinnabar, orpiment, gold, azurite, and malachite, and porcine glue as binding material. These results provided important scientific data for the production crafts of the precious Tara thangkas, contributing to the revelation of its value in art history and enabling conservators to make informed conservation decisions.

Tin and Bronze Production at the Outeiro de Baltar Hillfort (NW Iberia)

Findings of Iron Age metallurgical activities related to tin metal and mining are very rare. In the present work, we present a detailed study of the Outeiro de Baltar hillfort, dated to the Late Iron Age/Early Roman period, located in a place where 20th century tin mining work took place. Elemental and microstructural analysis by portable, micro and wavelength dispersive X-ray fluorescence spectrometry (pXRF, micro-XRF and WDXRF) and scanning electron microscopy with energy dispersion spectrometer (SEM-EDS) showed that metallurgical debris found at the archaeological site is related to tin smelting and binary and ternary bronze productions. Analysis of the artefacts of diverse typologies found at the site showed that a variety of metals and alloys were in circulation and use. Samples of tin ores (cassiterite) from the region were analyzed for comparison with an archaeological tin slag from the site. The analytical results point to the production of tin metal using local cassiterite and the production of bronze by directly adding cassiterite into a smelting process. Furthermore, data of remote sensing (airborne Light Detection and Ranging (LiDAR) and historical aerial imagery) and Geographical Information System (GIS) mapping were combined with archival mining documentation and maps to retrieve a landscape context for the site. The study showed that the place of the Outeiro de Baltar hillfort (NW Iberia) was mined periodically over time.

Artificial weathering of rock types bearing petroglyphs from Murujuga, Western Australia

AbstractMurujuga in Western Australia has the largest concentration of ancient rock engravings (petroglyphs) in the world. However, the Murujuga rock art is potentially threatened by local industrial air pollution, in particular by acid rain, but unambiguous scientific evidence is still missing. Here, we report on results of an accelerated weathering experiment, simulating Murujuga weather and climate conditions that was designed and performed to test whether the expected small changes in chemical, mineralogical, and physical characteristics of the rock surface can be detected and reliably quantified by various analytical means. Locally acquired Murujuga granophyre and gabbro samples with natural varnish were artificially weathered for up to four months in a climate chamber under conditions that simulated 2 years of natural weathering. Mineralogical, chemical, and physical changes were qualitatively monitored by X-ray diffraction and confocal Raman spectroscopy, and quantified by colorimetry, portable X-ray fluorescence spectrometry, and micro-computed tomography. In addition, artificial rainwater that was sprinkled over the rock samples was collected and analysed by inductively-coupled plasma mass spectrometry. The results show significant chemical and physical changes of the surfaces of the rock varnish after 1 month of artificial weathering. The analytical results demonstrate that it is possible to quantitatively monitor small changes caused by the weathering of gabbro and granophyre. Therefore, such a semi-actualistic experimental approach, when carefully designed, potentially allows testing the hypothesis that the weathering rate of the Murujuga petroglyphs is increased by local industrial air pollution. Further experimental work is currently under way.

Proximal sensor data fusion for tropical soil property prediction: Soil fertility properties

Proximal sensors have proven capable of predicting multiple soil properties under different conditions. However, doubts remain about which sensor is preferable for delivering optimal prediction models and which preprocessing methods produce the most accurate results. Portable X-ray fluorescence (pXRF) spectrometry and visible near-infrared (Vis-NIR) diffuse reflectance spectroscopy have been widely used, while the NixProTM color sensor has been explored more recently. This study evaluated the use of pXRF, Vis-NIR, and NixProTM data to predict soil organic matter content (SOM), pH, base saturation (BS), the sum of bases (SB), cation exchange capacity (CEC) at pH = 7 and effective CEC (eCEC), via each sensor in isolation, and via combined sensors data. Moreover, factors interfering in the prediction models' accuracy (data preprocessing methods, soil horizon, soil class, parent material) were used as auxiliary variables. 604 soil samples were collected in Brazil, encompassing ten soil orders and 19 parent materials. Numerical and categorical prediction models (7,980) were created for six soil properties using a random forest algorithm, totaling 7980 models, delivering almost 24,000 results., Coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), and residual prediction deviation (RPD) were used for validation of numerical predictions., Overall accuracy and kappa coefficient were calcualted for categorical predictions. Although the combination of sensors provided most of the best predictions, pXRF in isolation achieved accuracies close to the three sensors combined. NixProTM offered superior contributions to SOM and CEC predictions, but pXRF and Vis-NIR were responsible for the best results of most studied variables. On average, by adding pXRF to Vis-NIR data, predictive accuracy improved 32%; while adding Vis-NIR to pXRF data increased accuracy by ca. 6%. Soil-order-specific models improved predictions for Ultisols compared to general models (without soil order distinction), reaching R2 > 0.90. Soil parent material and horizon did not improve models significantly. Categorical predictions improved the accuracy for some properties, reaching an overall accuracy of 100% and kappa index of 1.0 for pH in A horizons of Ultisols via pXRF + Vis-NIR data. Proximal sensor data with no auxiliary variables provided almost all the best results. The fusion of proximal sensors can provide better predictions, but pXRF alone can deliver satisfactory results in most cases for the six soil properties.

“Foundations of a great metaphysical style”: unraveling Giorgio de Chirico’s early palette

Properly situating Giorgio de Chirico’s metaphysical works within his lifetime is complicated due to incomplete provenances, his practice of deliberately falsifying dates, and the known existence of forgeries. De Chirico’s palette may have altered over time, due to shifts in his personal taste, changes in availability of materials, and innovations in paints; elucidating his palette and variations thereof during his metaphysical period (1911–1919) offers analytical insights that complement traditional connoisseurship when attempting to correctly position a given work within his lifetime. To this end, eleven paintings from his metaphysical period, and two in his metaphysical style but painted in the 1940s and backdated to the 1910s, were analyzed by non-destructive portable X-ray fluorescence spectroscopy. Analysis of some works was further complemented with micro-destructive analysis by scanning electron microscopy coupled with energy dispersive x-ray spectrometry, as well as Raman and Fourier transform infrared spectroscopy. While the grounds of his paintings are variable, his metaphysical palette is consistent and includes: lead white, zinc white, ochres and umbers, magnetite, bone or ivory black, vermilion, chrome yellow, Naples yellow, copper acetoarsenite, chromium oxide green, and Prussian blue. Less commonly used pigments include cerulean blue and cadmium yellow, and the backdated paintings lack lead white and vermilion.

Soil and climate effects on winter wine produced under the tropical environmental conditions of southeastern Brazil

Southeastern Brazil is an emergent region in terms of the production of high-quality fine wines. To contribute to typicity assessment, the soils (morphology, mineralogy, chemical and physical analyses), parent material (geologic maps and portable X-ray fluorescence spectrometry) and climate (temperature and precipitation) were characterized in seven vineyards located in the state of Minas Gerais and São Paulo, Brazil, by carrying out state-of-the-art terroir analysis and assessing the environmental variations of the study sites. A soil profile was described and sampled in the central part of each vineyard. Principal Component Analysis (PCA) biplots were used to analyze the relationships between these factors and the composition of wines (2016, 2017 and 2018 harvests) produced from Syrah in commercial vineyards in different municipalities of Três Corações (TC), Cordislândia (COR), Andradas (AND), São Sebastião do Paraíso (SSP), Três Pontas (TP), Espírito Santo do Pinhal (PIN) and Itobí (ITO). The vineyards were grouped according to soil and climate characteristics. Group A was composed of COR, AND and PIN vineyards, which exhibited the highest correlation with soil Al3+ content and accumulated rainfall. The group’s wines had the lowest ash alkalinity, total polyphenol index (TPI) and pH values and the highest fixed acidity. Group B consisted of the TP and TC vineyards, which had the highest soil organic matter and boron contents and the highest thermal amplitude with similar values (15.4 °C in TC and 15.2 °C in TP); their wines showed average composition. Group C comprised ITO alone, which was characterized by the shallowest and least developed soils. Its wine had the highest flavonol content and high dry extract, color intensity, TPI, alcohol content and sugar values. Group D contained the SSP vineyard, in which the soil subsurface horizons were correlated with the highest wine pH. Late harvest in this vineyard caused the most dehydration of grapes and consequent concentration of most wine compounds (human effect on terroir). The terroir information produced in this study adds substantial value to the wines produced under the tropical environmental conditions of southeastern Brazil, for which such studies are very rare. By characterizing the natural factors (soil, soil parent material and climate) and human factors (vineyard management and wine characteristics) related to terroir, this study can also provide historical information about the wine from this emergent region (the historical factors). In addition, its results can be used to guide producers in their choice of vineyard cultivation sites according to preference in wine composition.

Using pXRF spectrometry for brick characterization and sourcing at Boone Hall Plantation

In the 18th century, Charleston, South Carolina, experienced a series of fires that prompted the city to pass laws requiring buildings to be constructed of fire-proof masonry, such as stone or brick. As a result, plantations with access to brickmaking materials began making brick, using the labor of enslaved people. Boone Hall Plantation, north of Charleston, was one of the largest and produced over 24 million bricks during its heyday from 1850 to 1860. Portable X-ray fluorescence spectrometry reveals the chemical fingerprint of Boone Hall bricks, and the method is tested here as a way to understand the architectural history of Boone Hall’s structures. The results can be applied throughout the region by providing a database for identifying the source of brick in Charleston structures. Brick sourcing provides a powerful personal connection between Charleston’s famous architecture and the enslaved people whose skilled labor made those buildings possible.

LIBS and pXRF validation for the removal of Pb by bio-CaCO3 nanoparticles from contaminated water

In this work, laser-induced breakdown spectroscopy (LIBS) was applied to qualitatively evaluate lead adsorbed from industrial wastewater by nano-CaCO3. Eggshell as a natural source of CaCO3 has been used as a sorbent owing to its low cost and unrivalled adsorption capacity to remove Pb from contaminated water. The structure and morphology of CaCO3 nano-powders were investigated using scanning electron microscopy (SEM), transmission electron microscope (TEM) and Fourier transforms infrared (FTIR). LIBS results were experimentally validated by the results obtained using portable X-ray fluorescence spectroscopy (pXRF) and energy dispersive X-ray (EDS), which confirmed the feasibility of using LIBS to detect traces of Pb ions, while the adsorption process is applied under governing parameters. Langmuir and Freundlich isotherm models were used to model the experimental data. The kinetics of adsorption mechanisms were studied using Lagergren's pseudo-first-order and McKay and Ho's pseudo-second-order. The obtained results demonstrated that bio-CaCO3 nanoparticles could be used as an effective lead-sorbent from wastewater. Accordingly, it is possible to utilize this adsorption technique as a promising practical approach for the treatment of lead-contaminated industrial wastewater and its recirculation.Graphical abstractHighlightsNatural nano CaCO3 from eggshell was prepared mechanically as a low-cost adsorbent and characterized by SEM, TEM, and FTIR.The capacity of removing Pb (II) by nano-CaCO3 was dependent on pH, metal concentration and contact time .LIBS was used for qualitative analysis of adsorbed Pb (II) and the results were validated with those obtained by EDX and pXRF spectrometry; in addition, isotherm models and kinetics of adsorption mechanisms were investigated.

Smartphone application for ancient mortars identification developed by a multi-analytical approach

The present work shows the results of the chemical, mineralogical and colorimetric characterisation of the ancient mortars from Silla Islamic Tower (Valencia, Spain) and Fuengirola Castle (Malaga, Spain). The samples were characterised from the mineralogical point of view by X-ray diffractometry and mid-infrared attenuated total reflection spectroscopy, while portable energy dispersive X-ray fluorescence spectroscopy and inductively coupled plasma mass spectrometry were employed to obtain the concentrations of major and trace elements, including rare earth elements. Data analysis through multivariate statistics was used to evaluate features to discriminate among the mortars from the different construction phases and to classify undated samples. Finally, colour features of powdered and intact samples were characterised by smartphone photo processing and with a Vis-spectrophotometer as reference technique to evaluate the effectiveness of smartphones for archaeometric studies of historic mortars. The analytical results permitted the classification of most undated samples from Silla and evidenced the presence of peculiar chemical characteristics in some samples from Fuengirola. Imaging data for powdered samples showed a good potential as a reliable, cheap and non-destructive fast method to characterise mortars and carry out the study of construction phases in historical complexes.

X-ray Fluorescence Spectroscopy of Picrolite Raw Material on Cyprus

Picrolite artefacts comprise some of the most distinctive material remains in the prehistory of the island of Cyprus, in the Eastern Mediterranean. Picrolite exploitation dates from at least 12,000 years ago for the manufacture of personal ornaments and items with a symbolic function. It is commonly assumed that picrolite nodules were collected in secondary deposits on an ad hoc basis. This narrative, however, ignores the fact that picrolite carriers can only be found in very specific locations on the island, discrete from each other. Here we report initial outcomes of the application of handheld portable X-ray fluorescence (HHpXRF) and synchrotron-based X-ray fluorescence spectroscopy (SR-μXRF) to the analysis of picrolite raw materials performed at the newly opened PUMA beamline of the SOLEIL Synchrotron Radiation Facility. Our work refines the basic characteristics of the elemental constituents of the picrolite raw material and highlights key micro-structural differences between two distinct source regions on the Troodos Massif in western Cyprus. Picrolite source characterisation is expected to contribute significant new knowledge to the study of rare raw material consumption, prehistoric social organisation, networking and possible long-distance exchange of this idiosyncratic raw material within and beyond the island’s geographic boundaries.

In situ XRF investigations to unravel the provenance area of Corinthian ware from excavations in Milazzo (Mylai) and Lipari (Lip\xe1ra)

In this contribution a non-destructive approach has been used aiming at investigating the chemical composition of 35 ceramic items belonging to the collections of the Regional Aeolian Museum “Luigi Bernabò Brea” in the Lipari Island (Sicily, Italy). Different vessel types have been selected for analysis, including aryballoi, kotylai, olpai, anforiskoi, oinochoai, and alabastra, belonging to the “Proto-Corinthian and Corinthian” ware classes. The items, dating back to the period comprised between the early eighth and the first half of the sixth century BC, come from two different archaeological sites in the province of Messina (Sicily), specifically the Istmo necropolis of Milazzo, in the northern Sicilian coast, and the acropolis and necropolis of Lipari, in the Aeolian islands. The chemical characterization of ceramics, carried out through portable X-ray fluorescence spectroscopy (pXRF), aimed at gaining information on the production area of examined items whose autoptic analysis pointed to Corinthian imports. The possibility of carrying out experimental investigations on the most ancient materials from the archaic necropolis of Milazzo and on fragments from Lipari, albeit limited to pXRF investigations, allowed to enrich the knowledge on the Corinthian production exported to western areas as well as to discriminate, no longer based solely on autoptic observations and stylistic evaluations, between Corinthian productions and "local" imitations.

Using Portable X-ray Fluorescence Spectrometry (PXRF) to Explore the Origins of the Sarsen Megaliths at Stonehenge

Stonehenge is a prehistoric monument that is considered a British cultural icon and one of the most famous landmarks in Europe. The origin of the sarsen megaliths that comprise Stonehenge have interested archaeologists for decades. What can spectroscopic techniques, such as portable X-ray fluorescence spectrometry (PXRF), reveal about the sarsen megaliths and where they originated? David Nash, a professor of physical geography at the University of Brighton in Brighton, United Kingdom, is exploring this question. We recently spoke with Professor Nash about his team’s discovery and what it means for the future of archaeology.

Using Portable X-ray Fluorescence Spectroscopy for Inexpensive and Quick Determination of Micronutrients in Barley Shoots

ABSTRACT Determination of elemental concentrations in plant tissue samples is critically important for analyzing their nutritional content. Micro-elemental analysis mostly relies on inductively coupled plasma (ICP) spectrometry techniques, which are expensive, time-consuming, laborious, and complicated. Portable X-ray fluorescence (pXRF) spectroscopy is widely applied in earth sciences but is rarely practiced to quantify elements in plant samples. In this pilot study, the reliability of pXRF results was compared with that of ICP-mass spectrometer (MS) to determine concentrations of four micronutrients zinc (Zn), iron (Fe), copper (Cu), and cadmium (Cd) in barley (Hordeum vulgare L.) shoot samples. Ground barley samples were scanned with the pXRF instrument. The concentrations of Zn recorded using this method correlated well with the ICP-MS results (R 2 = 0.80), while Fe and Cu concentrations showed moderate correlations (R 2 = 0.57 and 0.42, respectively). However, no significant correlation was found between ICP-MS- and pXRF-derived concentrations for Cd (p > .05). This work demonstrated the potential of pXRF as a reliable and cost-effective alternative to ICP methods for determining Zn in plant samples as it allows the analysis of a greater number of samples in a short period at considerably less expense.

Variation of properties of two contrasting Oxisols enhanced by pXRF and Vis-NIR

Oxisols are generally deep, weathered-leached soils that present morphologically homogeneous profiles. Despite their apparent homogeneity, different parent materials and pedogenetic processes grant these soils diverse chemical and mineralogical attributes. Proximal sensors might help to detect the variability of soil attributes along such old and deep profiles. The objective of this study was to investigate the physical, chemical and mineralogical variability of Oxisol profiles originated from different parent materials with aid of visible and near-infrared diffuse reflectance spectroscopy (Vis-NIR DRS) and portable X-ray fluorescence (pXRF) spectrometry, in order to evaluate if these proximal sensors can complement the analysis of these deep and weathered tropical soils. Two Oxisol profiles were selected: Anionic Acrudox (AA) and Typic Hapludox (TH). One hundred samples were collected in each profile down to 2 m of depth, following a grid of 10 × 10 cm, for pXRF, Vis-NIR and XRD analyses. Vis-NIR DRS spectra provided key mineralogical information in agreement with X-ray diffraction results, showing differential occurrence of kaolinite, hematite, maghemite and gibbsite/kaolinite ratio in these profiles. PXRF detected high chemical variability across the profiles and allowed to map the spatial chemical distribution of both soils. Proximal sensors provided an inexpensive and efficient way to help complement the identification of meaningful variability across Oxisol profiles that remained even after the long formation process of these very weathered tropical soils.

Quantifying and characterising metal concentrations in Derwent Estuary sediments using portable X-ray fluorescence spectrometry

The Derwent Estuary is highly enriched in potentially toxic elements, such as Zn, Pb, Cu, As, Hg and Cd, owing to inputs from historical industrial activity adjacent to the river, predominantly prior to strict environmental protections introduced in the 1970s. Contaminants are now buried at shallow depths within the sediment profile, in one or two highly concentrated layers decreasing in concentration away from an electrolytic zinc refinery, regarded as the main source of the contaminants. Enriched metals (Zn, Pb, Cu, Cd and As) in the estuary were estimated from data collected from 37 sediment cores using a portable X-ray fluorescence spectrometer that was validated against inductively coupled plasma mass spectrometer analyses. The thickness of the metal and metalloid enriched layers ranges from 32.5 to 107.5 cm, with an average thickness of 63 cm. Sedimentation rates based on this layer and the time since the start of zinc processing are approximately 0.46 cm/year. Sedimentation rates based on the thickness since maximum metal and metalloid concentrations are between 0.17 and 1.64 cm/year. Based on these sedimentation rates, the average time it will take for surface sediments to return to background metal and metalloid concentrations, if left undisturbed, is approximately 123 years. KEY POINTS Metal contaminant concentrations in Derwent Estuary sediments have two clear peaks in concentrations at depth, where estuary sediments have been enriched at varying rates over the last 97 years. The contaminated layer varies in thickness throughout the estuary, but has an average thickness of 63 cm, a maximum thickness of 107.5 cm and a minimum thickness of 32.5 cm, from surface sediments to the bottom of contamination. All surface sediments were enriched in metals or metalloids, but the overall trend in metal concentrations is decreasing from a major enrichment peak to moderate concentrations at the sediment–water interface. The time required for surface sediments to return to acceptable concentrations as defined by the ISQG is estimated to be on average 123 ± 88 years for the whole estuary with different parts of the estuary returning to background at different times.

Multi-Technique Diagnostic Analysis of Plasters and Mortars from the Church of the Annunciation (Tortorici, Sicily).

Plasters and mortars of the Church of the Annunciation (Tortorici, Sicily) were characterized, for the first time, both at the elemental and molecular levels, by means of portable X-ray fluorescence (XRF) and Raman spectroscopy, to achieve information on the “state of health” of the whole structure. The understanding of their degradation mechanisms and the identification of consequent degradation patterns can define the environmental factors responsible for interpreting the potential pathological forms that can impact the general building vulnerability. In this sense, the results obtained in this article provide relevant information to identify and address both the characterization of building materials and the fundamental causes of their deterioration. At the same time, if coupled with the attempt to supply a chronological order of the major restoration interventions carried out on the investigated site, they provide new insights to calibrate the models for building vulnerability studies.

A Matrix Effect Correction Method for Portable X-ray Fluorescence Data

Portable X-ray fluorescence spectrometry (pXRF) is an analytical technique that can be used for rapid and non-destructive analysis in the field. However, the testing accuracy and precision for trace elements are significantly affected by the matrix effect, which comes mainly from major elements that constitute most of the matrix of a sample. To solve this problem, many methods based on linear regression models have been proposed, but when extreme values or outliers occur, the application of these methods will be greatly affected. In this study, 16 certified reference materials were collected for pXRF analysis, and the major elements most closely related to the elements to be measured were employed as correction indicators to calibrate the analysis results through the application of multiple linear regression analysis. Some statistical parameters were calculated to evaluate the correction results. Compared with the calibration data obtained from simple linear regression analysis without taking major elements into account, those corrected by the new method were of higher quality, especially for elements of Co, Zn, Mo, Ta, Tl, Pb, Cd and Sn. The results show that the new method can effectively suppress the influence of the matrix effect.

Determination of trace element concentrations in organic materials of “intermediate-thickness” via portable X-ray fluorescence spectrometry

This research explored the feasibility of using portable X-ray fluorescence (pXRF) spectrometry to quantify Fe, Cu, Zn, and As concentrations in dried and ground organic materials (fungi, vegetation, and animal tissues) with intermediate thickness.

Relationship between elemental content determined

Context Studies comparing the elemental contents obtained via portable X-ray fluorescence (pXRF) spectrometry under different scanning conditions and traditional time-consuming concentrated acid-digestion-based methods are rare in tropical soils. Aims (1) To compare the contents of Al, Ca, Cu, Fe, K, Mn, Zn, Cr, Ni, Ti, V and Zr obtained by pXRF with the results of the USEPA 3051a method; and (2) to evaluate the impacts of different conditions on the pXRF results. Methods Soil samples were analysed with pXRF under five conditions: field (F), post-field (PF), air-dried fine earth (ADFE, <2 mm), macerated (M), and macerated and sieved (MS, <150 μm). Linear regressions were adjusted between the USEPA 3051a and pXRF results for the five conditions. Coefficient of determination (R2), root-mean-square error (RMSE), and residual prediction deviation (RPD) were used as validation parameters for the models. Key results The different scanning conditions provided contrasting results for the total elemental contents via pXRF. The validation generated good models, as indicated by the condition, R2, and RPD values, and the results were, respectively: Ca (M; 0.88; 3.00), Cu (F; 0.91; 3.29), Fe (ADFE; 0.94; 4.14), Mn (F; 0.85; 2.65), Cr (ADFE; 0.86; 2.77), and Ni (ADFE and M; 0.74 for both; 2.10 and 2.08). Conclusions PXRF can accurately determine the contents of Ca, Cu, Fe, Mn, Cr and Ni in tropical soils compared with the 3051a method. Implications Results of the USEPA 3051a method can be accurately predicted via pXRF and regression models, reducing time, cost and work required.

Associations of digestibility with phenotypic and genetic variation in methane production in Angus cattle

Context Cattle and sheep emit methane, a potent greenhouse gas, as part of the fermentation process of feed digestion in their gut; however, the mechanisms explaining differences among animals in enteric methane production are not fully understood. Aim To investigate whether variation among animals in their ability to digest their test ration was associated with phenotypic and genetic variation in methane production. Methods The experiment used 135 Angus beef cattle measured for their phenotypic and genetic merit for methane production. The extent of digestion of the dry matter (DMD) in the test ration by individual cattle was determined using silica as a naturally present indigestible marker. Its concentration in feed consumed and faeces was determined using rapid portable X-ray fluorescence spectroscopy, from which DMD was calculated. Key results Higher daily methane-production rate (MPR), higher methane produced per unit of feed consumed (methane yield; MY) and higher methane produced than the predicted daily production (residual MPR; RMP) by animals was accompanied by higher DMD. Higher genetic merit for MPR was also accompanied by higher DMD, but DMD had no detectable association with genetic variation in the other two methane emission traits. The regression coefficients for change in MPR (g/day), MY (g/kg DMI), RMP (g/day) with change in DMD (%) were 2.6 ± 1.1 (s.e.; P < 0.05), 0.14 ± 0.07 (P < 0.1) and 0.68 ± 0.38 (P < 0.1) respectively. Conclusions Differences among animals in their DMD were found and were associated with phenotypic variation in the three methane emission traits studied, and with genetic variation in daily methane production. The results support the caution that feeding and breeding interventions seeking to reduce methane emissions can also reduce the extent of digestion of feed by cattle. Implications Feeding and breeding interventions that seek to reduce methane emissions may change rumen physiology and reduce the extent of digestion of feed by cattle, which may be undesirable.