Portable X-ray Fluorescence Spectrometer Research Articles

Different Quartz Varieties Characterized by Proximal Sensing and Their Relation to Soil Attributes

Quartz is one of the most common minerals in soils, mostly present in sand and silt fractions. Although quartz is basically formed of SiO2, other elements can be easily detected and assessed nowadays using a portable X-ray fluorescence (pXRF) spectrometer. Our study aims to evaluate the chemical composition of different quartz varieties, identifying their main elements, and relating them to soil attributes. Six quartz varieties (hyaline, amethyst, milky, rose, smoky, and ferriferous) were analyzed via pXRF and 13 oxides/trace elements were identified and used for quartz discrimination (Al2O3, CaO, P2O5, SiO2, Cl, Cr, Fe, K2O, Mn, Rb, S, Ti, and V). Hyaline quartz was characterized by the highest SiO2 and the lowest contents of other elements. Al2O3 was the second-highest compound present in all varieties of quartz, reaching 21,547 mg kg−1 in the smoky variety. S, P2O5, Cl, SiO2, and K2O were the main components determined by Random Forest algorithm for discriminating quartz varieties. Some elements detected may serve as a reserve of nutrients to plants to be released in soils along weathering, depending on quartz particle size, soil texture, leaching, and associated attributes. pXRF enhanced the information on chemical characterization of quartz varieties, without the generation of chemical pollutants.

Portable x-ray fluorescence calibrations: Workflow and guidelines for optimizing the analysis of geological samples

The use of portable Energy Dispersive X-Ray Fluorescence (pXRF) spectrometers has exploded within the last decade for e.g., environmental, geological, and archaeological field research. Producing reliable geochemical data using a pXRF is a challenging process that requires the development of dedicated and matrix-matched empirical calibrations. Although a large field of applications, several research papers are still published using unquantified pXRF data, using manufacturers' built-in calibrations unsuitable for targeted rocks, or interpreting chemical concentrations without checking the limit of quantification of the pXRF spectrometer and its calibration model. In this paper, we present a general workflow for building an empirical calibration model for a pXRF spectrometer, from choosing reference materials to validating calibration's efficiency and quantifying its limit of quantification. We also compare the geochemical results on a sedimentary and an igneous rocks suite obtained from thirty-two calibration models that were built using different software available, including a simple homemade spreadsheet, the EasyCal calibration software, a free and open-source calibration app named CloudCal, and the built-in GeoMining and GeoExplorer calibrations provided by Bruker manufacturer on the Tracer 5 pXRF. This decoupled approach allows (i) to explore the pros and cons of each calibration model and determine which empirical calibration model brings the most accurate chemical concentration for a sedimentary and an igneous rock suite, (ii) to weigh the impact of each calibration parameter (type of regression line, spectral interferences, normalization, influence coefficients, multiple conditions of excitation and acquisition) on the accuracy of geochemical concentrations on rock samples and (iii) to bring innovative tools to assess the limits of quantification of a newly built calibration model.

Tracing the origin of deposited sediments: A study applying proximal sensing in a drainage subbasin

Erosion is a major cause of soil degradation. Understanding the sources of sediment and the processes that exacerbate this problem is crucial for soil conservation. Remote and proximal sensing technologies have contributed to advance our understanding of soil erosion processes and support soil conservation research. The objective of this study is to use two proximal sensors, a portable X-ray fluorescence spectrometer (pXRF) and a magnetic susceptibilimeter, to identify the origin of sediments deposited in the lower portion of a drainage subbasin by using a fingerprinting approach. Five sediment tracing elements were selected: Fe, Si, Al, Ti, and Zr. The sediment source area is composed of gabbro, granite, and felsic orthogneiss, upon which two soil classes were formed: Rhodic Ferralsol (Dystric) (Latossolo Vermelho Distroférrico típico, LV) and Haplic Acrisol (Argissolo Vermelho-Amarelo Distrófico típico, PVA). In the source area, 35 samples were collected from the topsoil layer (0–2 cm of depth) using a regular grid of 50 × 50 m2. In the deposition area, 24 samples were collected in a regular grid of 7 × 7 m2. The source of the sediments was determined using cluster analysis with data provided by the proximal sensors and topographic attributes. Results indicated that the Haplic Acrisol, which is more susceptible to erosion, contributed most to sediment deposition. Analysis of pXRF data showed its potential to identify and differentiate sediments and their sources. Cluster models based on the abundance of Fe, Si and Al, as well as the Ti/Zr ratio, demonstrated the best results with a global accuracy of 88% and a Kappa coefficient of 0.74. The use of the susceptibilimeter data alone did not yield satisfactory results. Results indicate the usefulness of pXRF in identifying the source of sediments in drainage basins, making it a valuable tool in soil conservation and erosion assessments.

Investigation of red substances applied to chank shell beads from prehistoric site of Qulong in Ngari Prefecture, Tibet, China

“Applying red” is a common phenomenon observed in Chinese archaeological sites, with the red pigments having been identified as red ochre or cinnabar if ever been scientifically analyzed. However, this is not the case for Tibet. Although a relatively large number of red-painted artifacts have been recovered in Tibet dating from the Neolithic Period to the Tubo Dynasty, little effort has been made on the pigment composition. Recently, nearly one hundred red substances covered shell beads made of the scared chank (Turbinella pyrum), a large conch from the Indian Ocean, were unearthed from the Qulong site (c. 800–500 BC) in the Ngari plateau, western Tibet. This shell beads assemblage represents the largest and most concentrated group of chank shell beads recovered in the Tibetan Plateau and its surrounding regions. It provides a crucial clue for exploring the local “applying red” tradition. In this study, eight shell beads excavated from the Qulong site were examined by the Portable Energy-dispersive X-ray Fluorescence Spectrometer (pXRF), X-ray diffraction (XRD), Fourier Transform infra-red spectroscopy (FTIR), and Laser Raman spectroscopy. The results are as follows: 1) the coloring agent of all red pigments on the shell bead is iron oxide, i.e., red ocher; 2) bone powder that has not been heated to high temperatures (above 600°C) and proteinaceous binders were added to the paint on the outer surface of sample QSM1-11a, but the thin layer on its interior surface was without bone powder; 3) bone powder was not added to the red residues on samples other than QSM1-11a, QSM1-13b, and QSM2-12. This research may reveal the complexity and diversity of the red substances applied to shell beads from Qulong, and shed light on our understanding of human practices and local customs in the Tibetan plateau and the surrounding areas in prehistoric times.

РЕНТГЕНОФЛЮОРЕСЦЕНТНЫЙ АНАЛИЗ МЕТАЛЛИЧЕСКИХ ИЗДЕЛИЙ ДЛЯ КОНСКОГО СНАРЯЖЕНИЯ ИЗ ПАМЯТНИКОВ БИЙКЕНСКОЙ КУЛЬТУРЫ (ФОНДЫ НАЦИОНАЛЬНОГО МУЗЕЯ РЕСПУБЛИКИ АЛТАЙ ИМ. А.В. АНОХИНА)

The exposition of the A.V. Anokhin National Museum of the Altai Republic (Gorno-Altaisk, Russia) demonstrates elements of horse equipment from two archaeological complexes of the Altai, which belong to the Biyke culture of the Arzhan-Mayemir time. The first set comes from the burial mound No. 2 of the Boytygem-II site, and the second comes from the burial mound No. 1 of the Aira-Tash-1 necropolis. These ancient objects are important for the cultural and chronological identification of the studied objects, as well as for the study of the material culture of the early nomads of Inner Asia. A portable X-ray fluorescence spectrometer was used to determine the chemical composition of the alloys of the metal objects. The article presents the results obtained, which reflect the general and special characteristics of the implemented technologies. These data complement the previously published information on the testing of similar parts ofhorse equipment from the sites of the Altai of the Early Scythian period.

Характеристика розподілу хімічних елементів у вертикальному розрізі торфів за допомогою рентген-флуоресцентного аналізу (родовище Гончари, Львівська область)

This article discusses the features of peat analysis using X-ray fluorescence (XRF) analysis in order to study its qualitative and quantitative elemental composition, including heavy metals. The distribution of chemical elements is an indicator of various processes in geochemical and biological systems, by using of which it is possible to reproduce the conditions of accumulation of mineral deposits. This analysis is an important component of a comprehensive study of peat formation features, the environmental friendliness of peat extraction, and also for determining the suitability of peat for industrial use. We analyzed the content of chemical elements in peat samples taken at different depths using a portable X-ray fluorescence spectrometer. The article considers the main characteristics of the spectrum of individual elements, depending on the atomic number. In order to establish the general regularity of the distribution of 20 chemical elements in peat samples, we performed a mathematical and statistical analysis of the obtained data: calculation of the main statistical characteristics of chemical elements distribution (average, minimum and maximum values, median, variance, coefficient of variation, etc.), calculation of correlation matrices, selection of typomorphic geochemical associations of chemical elements using cluster and factor analyses. We singled out two types of factors that are decisive and influence the accumulation of chemical elements in the investigated peat: “organogenic” and “natural” (lithological), which are decisive, and a secondary factor –anthropogenic. We compared the obtained results with the average values obtained from the results of spectral semi-quantitative analysis of peat ash samples taken at depths of 0.1–7 m in the same region. We evaluated the possibility and efficiency of using a portable X-ray fluorescence spectrometer for the analysis of the macro- and microelement composition of peats with different ash content. It has been established that portable X-ray fluorescence analysis is a powerful tool for fast and high-quality elemental analysis of peat, and the range of its application depends on specific research goals and tasks.

ASSESSING METAL RECOVERY OPPORTUNITIES THROUGH BIOLEACHING FROM PAST METALLURGICAL SITES AND WASTE DEPOSITS: UK CASE STUDY

Recovery of metals from former industrial areas (also called brownfields) and closed landfill sites, are critical for future sustainable development and reducing the environmental risks they posed. In this study, the feasibility of using bioleaching for resource recovery of raw and secondary raw materials from a former metallurgical site and deposit (PMSD) located in the UK was investigated. Determination of the physicochemical parameters (conductivity, pH, moisture and ash content) that can affect bioleaching performance along with metal content analysis were carried out. Field measurement were also carried out using a portable X-ray fluorescence (pXRF) spectrometer as a rapid measurement tool and compared with the induced coupled mass spectrometry (ICP-MS) results. Fe (469,700 mg/kg), Ca (25,900 mg/kg) and Zn (14,600 mg/kg) were the most dominant elements present in the samples followed by Mn (8,600 mg/kg), Si (3,000 mg/kg) and Pb (2,400 mg/kg). The pXRF results demonstrated minimal variance (<10%) from the ICP-MS results. The preliminary assessment of bioleaching using Acidithiobacillus ferrooxidans at 5% pulp density with 22 g/L energy source and 10% (v/v) inoculum at pH 1.5 showed that 100% of Ti and Cu, 32% of Zn and 24% of Mn was recovered from the sample material, highlighting opportunities for the recovery of such metals through bioleaching processes.

Analysis and Characterization of the Soteria Mosaic in the Antakya Museum with Archeometric Techniques

Mosaic, like all other branches of art, is one of the most important aesthetic ties that human beings establish with the world. When we look at the mosaic, we can see the changing traces of the past and relive the time that has been forgotten for a long time. Mosaic is an eternal art that has endured natural conditions such as wind and rain and has survived to the present day with slight damages. This study was carried out in three stages. First, the stone tessera of the Soteria mosaic were color analyzed using the portable Color Detector X-Rite CAPSURE precision color measuring instrument. The tesserae were then analyzed using the Energy Dispersive Portable X-Ray Fluorescence Spectrometer device, which is a non-destructive method for quantitative analysis of its elements. In the next stage, petrographic analysis was performed in laboratory environment to determine the rock type and minerals of 10 stone tessera belonging to the Soteria mosaic. As a result, the examination of the qualities and contents of the materials used in the mosaics; By establishing a connection between the past, present and future, it will be able to make important contributions in revealing the reasons why the mosaics have survived to the present day.

Geochemical characterization of Jordanian basalts using portable X-ray fluorescence spectrometry and sourcing of the Amman Theater Statue

Despite the prevalence of basalt as a raw material for sculpture, architecture, and artifacts in Iron Age Jordan, geochemical characterization and sourcing of these artifacts to their geologic point of origin is rarely performed, in part due to the lack of a database of geologic basalt sources. In order to address this problem, for this study, geologic basalt samples were collected from Al Hashemiya (A & B), the Wadi Mujib Rim, Baluʿ, Karak, Dana, and Umm Qays and analyzed using an Olympus Vanta portable x-ray fluorescence (pXRF) spectrometer. Previously collected samples from Wadi Zarqa Maʿin that were analyzed by wavelength dispersive x-ray fluorescence (WD-XRF) were also included but were not re-analyzed. Analyses were also conducted on the Amman Theater Statue and results were compared to our compiled data, which determined that the most likely geologic source for this basalt artifact is the source we identify as Al Hashemiya A. By publishing characterization data from these sources, we hope to provide a resource for archaeologists and archaeometrists throughout the region.

Examination of Metal Finds from the 10th Century Cemetery of Kiskunfélegyháza (Hungary)

This case study presents the results and conclusions of chemical and metallographic analyses carried out on metal finds (gilded silver mounts, jewelry made of silver- and copper-based alloys, and iron horse fittings) found in nine graves excavated at the 10th century site of the Terjék-tanya at Kiskunfélegyháza (Hungary). The examinations were performed with portable handheld X-ray fluorescence spectrometer (ED-XRF), optical microscopy (OM) and scanning electron microscopy equipped with an energy dispersive spectroscope (SEM-EDS). Beside the determination of the chemical composition of the non-ferrous artefacts and the inclusions of the iron samples, the aim of the study was to detect traces and characteristics of different manufacturing methods such as fire gilding, forging, etc.

Virtual reconstruction of the painting process and original colors of a color-changed Northern Wei Dynasty mural in Cave 254 of the Mogao Grottoes

The Northern Wei Dynasty (386–534 CE) murals of Cave 254 in the Mogao Grottoes, China, have been extensively affected by pigment color changes and fading. These issues severely hinder efforts to correctly understand the value and painting process of murals from this historic period. The virtual reconstruction of the faded murals reflects the analysis results of the pigments applied during the painting process and provides a new direction for conservation and art research. However, simple virtual reconstructions may not be accurate owing to deficiencies in our understanding of the color-changed pigments and fading of image lines. In this study, multi-band imaging (MSI) was performed to obtain infrared-reflected false color, ultraviolet-reflected false color, and ultraviolet luminescence images of the mural. A portable X-ray fluorescence spectrometer, portable digital microscope, scanning electron microscope, energy dispersive X-ray spectrometer, liquid chromatography–mass spectrometer, and confocal Raman microscope were used. Non-invasive and minimally invasive analyses of local portions of different color areas were performed to identify their pigments and map the strata, and a hue–saturation–brightness palette was constructed for these pigments. Finally, the pigment analysis results were combined with the multi-band image features to determine the pigment distribution of the mural, which was then used to virtually reconstruct the original color and appearance of the faded mural under ideal conditions. This study is the first to use a virtual reconstruction based on objective analyses to simulate the original color, painting processes, and pigment stratigraphy of a mural from the Northern Wei Dynasty. A preliminary discussion of the relationship between the painting processes of the mural and color changes in its pigments was also performed. The findings of this study will provide new perspectives on the study of Northern Wei Dynasty murals.

Nondestructive discrimination of black ceramic prints on automotive glasses by portable X-ray fluorescence spectrometer.

Automotive glasses are important forensic evidence often recovered from crime scenes. Black ceramic prints on automotive glasses contains various elements in high concentrations. A portable X-ray fluorescence spectrometer (pXRF) allows an instant and nondestructive analysis of various elements. In this study, the Bruker Tracer 5g was used as the pXRF equipment. The NIST SRM612 glass standard was used to determine the limit of detection (LODs) of a pXRF and its optimal conditions. The acceleration voltages of 15, 30, and 50 kV were appropriate for measuring Si Kα (1.740 keV)-Ni Kα (7.473 keV), Cu Kα (8.042 keV)-Pb Lα (10.552 keV), and after Bi Kα (10.839 keV), respectively. The pXRF was used to compare 37 black ceramic prints on automotive glasses from the known source. The samples were divided into two groups: the Pb type and the Bi type. The samples were compared in pairs. The most appropriate and effective indicators for discriminating between the Pb and Bi type of black ceramic prints on automotive glasses were Zr Kα /Pb Lα and Cu Kα /Cr Kα for the Pb type, and Zr Kα /Bi Lα and Cu Kα /Crα for the Bi type, respectively. The samples were compared with other elements detected by pXRF to further discriminate them. 98.9% of all pairs were successfully discriminated. Results showed that black ceramic prints on automotive glasses are able to be discriminated by pXRF.

Analysis of geochemical patterns in a soil profile over mineralized bedrock

Transported soils cause difficulties in the identification of geochemical anomalies. It has been demonstrated that the joint application of local singularity analysis (LSA) and principal component analysis (PCA) can identify geochemical anomalies effectively, especially in regolith-covered areas. However, more convincing evidence is needed to explain the reasons for this. In this study, a soil profile overlying several mineralized veins cutting through bedrock was analysed in situ using a portable X-ray fluorescence spectrometer. The patterns of two mineralization-related elements, Cu and Mo, were analysed. The results revealed that the element concentrations of the soil sharply decreased as the distance from the bedrock increased, and this relationship can be described by a power-law model. LSA enhanced several vein-like anomalies corresponding to the mineralization veins in the bedrock, and the presence of vertically elongated weak anomalies in the soil indicates the migration of ore elements originating from the underlying bedrock through the soil. The statistics show that the patterns of the local singularity index (LSI) are stable at different depths and in different media, whereas the concentration patterns are not. In addition, the mineralization-related elements have a higher correlation coefficient for the LSI than for the concentration. Since a previous simulation study determined that a mineralization-indicative first principal component prefers that the variables have a close relationship and that the variables have similar patterns in different geological objects, the patterns discovered in this study explain why LSA is effective in identifying geochemical anomalies, especially when combined with PCA. Supplementary material: the high-resolution photo, the element concentration data and the lithologic data of the profile are available at https://doi.org/10.6084/m9.figshare.c.5957122 Thematic collection: This article is part of the Applications of Innovations in Geochemical Data Analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis

Portable Total Reflection X-ray Fluorescence Spectrometer with a Detection Limit in the 100 ng/L Range

Portable Total Reflection X-ray Fluorescence Spectrometer with a Detection Limit in the 100 ng/L Range

Using pXRF and vis-NIR spectra for predicting properties of soils developed in loess

Visible near-infrared (vis-NIR) and portable X-ray fluorescence (pXRF) spectrometers have been increasingly utilized for predicting soil properties worldwide. However, only a few studies have focused on splitting the predictive models by horizons to evaluate prediction performance and systematically compare prediction performance for A, B, and combined A+B horizons. Therefore, we investigated the performance of pXRF and vis-NIR spectra, as individual or combined, for predicting the clay, silt, sand, total carbon (TC), and pH of soils developed in loess, and compared their prediction performance for A, B, and A+B horizons. Soil samples (176 in A horizon and 172 in B horizon) were taken from Mollisols and Alfisols in 136 pedons in Wisconsin, USA and analyzed for clay, silt, sand, pH, and TC. The pXRF and vis-NIR spectrometers were used to measure the pXRF and vis-NIR soil spectra. Data were separated into calibration (n = 244, 70%) and validation (n = 104, 30%) datasets. The Savitzky-Golay filter was applied to preprocess the pXRF and vis-NIR spectra, and the first 10 principal components (PCs) were selected through principal component analysis (PCA). Five types of predictor, i.e., PCs from vis-NIR spectra, pXRF of beams at 0–40 and 0–10 keV (XRF40 and XRF10, respectively) spectra, combined XRF40 and XRF10 (XRF40+XRF10) spectra, and combined XRF40, XRF10, and vis-NIR (XRF40+XRF10+vis-NIR) spectra, were compared for predicting soil properties using a machine learning algorithm (Cubist model). A multiple linear regression (MLR) model was applied to predict clay, silt, sand, pH, and TC using pXRF elements. The results suggested that pXRF spectra had better prediction performance for clay, silt, and sand, whereas vis-NIR spectra produced better TC and pH predictions. The best prediction performance for sand (R2= 0.97), silt (R2= 0.95), and clay (R2= 0.84) was achieved using vis-NIR+XRF40+XRF10 spectra in B horizon, whereas the best prediction performance for TC (R2= 0.93) and pH (R2= 0.79) was achieved using vis-NIR+XRF40+XRF10 spectra in A+B horizon. For all soil properties, the best MLR model had a lower prediction accuracy than the Cubist model. It was concluded that pXRF and vis-NIR spectra can be successfully applied for predicting clay, silt, sand, pH, and TC with high accuracy for soils developed in loess, and that spectral models should be developed for different horizons to achieve high prediction accuracy.

Analytical Study of Overlooked Bronze Age and Iron Age Goldwork from Northwest Portugal

To gain further insight into the use of native gold and intentional gold alloys during the Bronze Age in Northwest Portugal, jewellery in the collections of three Portuguese museums was studied using an in-house built portable X-ray fluorescence spectrometer. Among the analysed objects are the Late Bronze Age bracelet from Monte Airoso (Viseu) and the Iron Age tubular bracelet from Regoufe (Aveiro). To shed more light on the manufacture of gold bracelets, have also been analysed all the components (bracelets, wires and bands) of the hoard of Arnozela (Braga), so far incompletely studied. The results obtained show that from the Middle Bronze Age onwards gold containing 8-11 wt.% silver is used, to which gradually increasing amounts of copper seem to have been added over time. These results support a heterogeneous chronology for the components of the hoard of Arnozela and show that the bracelet from Monte Airoso is made from an intentional gold alloy used in the Portuguese area during the Late Bronze Age. On the contrary, the bracelet from Regoufe is made from native gold without addition of copper. This could indicate that at least during a certain period the goldsmiths used both native gold as found and intentional alloys.Two other objects, discussed on the light of the data obtained for the bracelets, complete the study. One of them is one of the two Portuguese Early Bronze Age gold sheet ornaments with cut parallel bands (so-called gargantilha de tiras), found in Braga. Without obvious signs of use-wear like other ornaments of the same type, and made, as expected, with gold hammered into sheet, this ornament is made from an alloy that seems to correspond to a later period using gold from another origin. Finally, the composition of some of the components of the Late Bronze Age-Iron Age string from Malhada (Vila Real), a set of gold decorated plaques made from punched gold sheet by using different and asymmetrical punches, supports the addition of small amounts of copper to gold to produce intentional alloys.

Research on Rapid Identification Method of Copper Concentrate and Its Smelting Slag

This research was based on the portable X-ray fluorescence spectrometer ( XRF ) to determine the content of copper and silicon in copper concentrate and its smelting slag. Taking the copper concentrate produced in typical mining areas in China and abroad and the smelting slag produced by various copper concentrate smelting processes as test samples, the content of silicon and copper was determined by XRF, and the silicon copper in copper concentrate and slag was studied. The distribution law of element content was calculated in order to realize the identification of the properties of the sample. By calculating the ratio of silicon to copper (Rsi/Cu), the rapid primary screening and identification of the solid waste property of the cargo can be realized at the port site. The results showed that: the preliminary screening of the solid material was judged as slag, suspected slag and copper concentrate when Rsi/Cu ≥5, 1≤Rsi/cu <5, and Rsi/cu <1, respectively. The established preliminary screening method had an accuracy rate of more than 95%.

Rapid Exploration Using pXRF Combined with Geological Connotation Method (GCM): A Case Study of the Nuocang Cu Polymetallic District, Tibet

The Nuocang Cu polymetallic district is located in western Gangdese, close to the south of the Luobadui–Milashan fault zone. A large number of metal deposits with the potential to be prospected, such as Chagele, Zhalong, Longgen, and Sangmola, have been found near this district. To further isolate the target prospecting area, we used a portable X-ray fluorescence spectrometer (pXRF) to conduct an in situ 1:10,000 soil pedogeochemical survey. The results show that the use of a pXRF combined with the geological connotation method (GCM) can accurately delineate the anomalies related to mineralization and highlight “weak” and “small” anomalies. It was also shown to effectively shorten the working cycle and ensure the continuity and timeliness of field work. Through sizing tests, the analysis of −10~+60 mesh soil samples achieved the best anomaly delineation effect. By studying the supra-ore, near-ore, sub-ore halo, and Th/U, the degree of denudation and the oxidation-reduction environment of the deposit were judged to be moderate. Ultimately, depending on the target area delineated by the pXRF, six Cu-Pb-Zn orebodies were uncapped by five exploratory trenches, which proved the potentiality of the Cu-Pb-Zn polymetallic epithermal deposit controlled by minor faults in Central Nuocang.

Heavy Metal Contamination of Soil in Preschool Facilities around Industrial Operations, Kuils River, Cape Town (South Africa).

The contamination of soil by heavy metals is a potential health risk, especially among susceptible populations. The aim of this study was to measure the levels of heavy metals, identify the contamination levels and possible sources of heavy metals, and evaluate the health risk caused by heavy metals to the children living in Kuils River. Composite samples of soil were collected at 34 preschools. A portable X-ray fluorescence spectrometer was used to measure the levels of metals. Contamination levels were evaluated using a geoaccumulation index (Igeo), enrichment factor (EF), contamination factor (CF) and pollution load index (PLI). The spatial distribution of the Igeo contamination levels was assessed using ArcGIS. Sources of heavy metals and the correlation among metals were assessed using factor analysis and Pearson correlation, respectively. The measured concentrations of metals were used to estimate the health risk for children. The average levels of the metals were 16, 4469, 137, 30, 176, 1547 and 232 mg/kg for arsenic (As), iron (Fe), manganese (Mn), lead (Pb), strontium (Sr), titanium (Ti) and zinc (Zn), respectively. According to Igeo, EF, CF and PLI contamination exist in the study area. The health index (HI) for non-carcinogenic effects showed the ingestion route as the main contributor to the total risk, with the accumulative carcinogenic risk exceeding the maximum acceptable level. To protect the affected communities, and children in particular, this study provides evidence of the need for action, including the institution of mandatory buffer zones between pollutant-generating activities and human settlements.

Geo-Accumulation Index of Manganese in Soils Due to Flooding in Boac and Mogpog Rivers, Marinduque, Philippines with Mining Disaster Exposure

This paper presents the effects of flooding on the accumulation of manganese (Mn) in soils within proximity of the Boac and Mogpog rivers in Marinduque of The Philippines. Marinduque, an island province in the Philippines, experienced two catastrophic tailings storage facility (TSF) failures in the 1990s that released sulfide-rich tailings into the two major rivers. The Philippines experiences 21–23 typhoons every year, 11 of which pass thru Marinduque that causing inundation of floodplain areas in the province. A flood hazard map developed using LiDAR DEM was utilized for the Boac and Mogpog rivers for an accurate representation of flooding events. A portable X-ray fluorescence spectrometer (pXRF) and a Hannah multi-parameter device were used for the on-site analyses of Mn concentration and water physico-chemical properties, respectively. Spatial grid mapping with zonal statistics was employed for a comprehensive analysis of all the data collected and processed. Correlation analysis was carried out on Mn concentrations in soil and surface water, electrical conductivity (EC), total dissolved solids (TDS), pH, temperature, curve number (CN), and flood heights. The curve number indicates the runoff response characteristic of the Mogpog-Boac River basin. The results show that 40% of the total floodplain area of Boac and Mogpog were subjected to high hazards with flood heights above 1.5 m. The Mn content of soils had a statistically significant moderate positive correlation with flood height (r = 0.458) and a moderate negative correlation with pH (r = −0.438). This condition suggested that more extensive flooding promotes Mn contamination of floodplain soils in the two rivers, the source of which includes the mobilization of Mn-bearing silt, sediments, and mine drainage from the abandoned mine pits and TSFs. There is also a strong negative correlation between pH and Mn concentrations in surface water, a relationship attributed to the solubilization of Mn-bearing precipitates based on geochemical modeling results. Using Muller’s geo-accumulation index, 77.5% of the total floodplain of the two rivers was identified as “moderately contaminated” with an average Mn soil content of 3.4% by weight (34,000 mg/kg). The Mn contamination map of floodplain soils in the Mogpog and Boac rivers described in this study could guide relevant regional, national, and local government agencies in planning appropriate intervention, mitigation, remediation, and rehabilitation strategies to limit human exposure to highly contaminated areas.