International Journal of PIXE

The great East Japan earthquake consisted of three catastrophes. The first one was the earthquake, the second one was the tsunami and the third one was nuclear power plant accidents. The magnitude 9 was recorded. After the earth quake, huge tsunami waves of above 16m height hit the east coast of Northeastern Japan. Many people died and many things were lost. The tsunami caused the accident of Fukushima first nuclear power plant which resulted in a serious radioactive pollution.

The space radiation dose rates at several points in Miyagi prefecture and their time dependencies were measured. Radiation exposure was mainly caused by ¹³¹I at the earlier stage of Fukushima first nuclear power accidents and then by ¹³⁴Cs and ¹³⁷Cs. We inspected radioactive contamination for food produced in Miyagi prefecture and Fukushima city. As the result, almost all food were safe.

We studied the structure of radioactive cesium distribution in soil and found the exponential dependence. This behavior could be explained theoretically. We developed a useful method to decontaminate the soil contaminated with radioactive cesium atoms. We applied our method to the contaminated school yards of elementary schools of Marumori town and decontaminated total area of about 7000 m².

Ion-Beam-Induced Luminescence (IBIL) spectra and images for the chemical states and crystal structures of micrometer-sized mineral targets were obtained by wavelength-dispersive IBIL analysis. A wavelength resolution of approximately 2 nm was achieved with a remote-controlled compact monochromator installed on an IBIL analysis system using a 3 MeV H⁺ microbeam. Several particulate mineral targets and aerosol samples were prepared on a carbon-plate sample holder that was selected to reduce the background noise and achieve a high S/N ratio in both the IBIL and Particle-Induced X-ray Emission (PIXE) analyses. The chemical composition of small targets that could not be well determined using micro-PIXE analysis was successfully visualized by the proposed IBIL analysis.

As a part of research project for food risk assesment in Asian countries, we have collected a variety of samples including dairy products from Mongolia for PIXE analysis. However, some kinds of milk products or fats such as butter, margarine, mayonnaise and cream are often hard to be homogenized with internal standards because of their viscosity and oiliness, which makes their sample preparation a tiresome work. We have tried to develop efficient preparation and measurement methods for in-air PIXE analysis of those samples. For butter and margarine, liquid internal standard method was taken after melting them with water bath. Pasty samples like mayonnaise and cream were mixed with liquid standard in agate mortar. The applicability of these methods was examined by checking homogeneity of so prepared samples on the basis of Ca concentration. Along with the internal standard methods, a standard-free method has also been worked out for those fatty samples. The obtained results have been fairly satisfactory and we have applied the methods to the Mongolian dairy samples.

The detection efficiency of the submilli-PIXE camera was improved by installing a new X-ray detector with a smaller distance from specimens. The distortion of elemental images caused by position dependent detection efficiency was corrected by estimating the detection efficiency based on the geometrical configuration of the detection system. The detection efficiency of characteristic X-rays from heavy elements such as iron and bromine became from 11 to 23 times higher than the previous system. The signal to noise ratios was improved from 1.8 to 2.5 times higher and detection limit was also decreased from 1/8 to 1/6 compared to the previous system. The in-air submilli-PIXE camera with improved detection system can be useful to biological applications.

NABESHIMA-DANTSU is the name of the first Japanese-made carpets which have been produced in the Nabeshima domain (Saga Prefecture) since the later Edo period. The NABESHIMA-DANTSU carpets have been woven from one kind of cotton, and have been dyed with various dyes and color fixatives. We analyzed pieces of the NABESHIMA-DANTSU carpets stored in the Saga Prefectural Museum and the Saga Prefectural Art Museum, by using PIXE method in order to detect dyeing methods used in them. We also analyzed dyes, color fixatives and cotton used in the traditional Japanese dyeing method. From the NABESHIMA-DANTSU carpets, small amounts of dyed and non-dyed samples were picked up and were analyzed by in-air PIXE system at Tohoku University. It was found that Fe and Cu are related to the parts dyed orange, and Al is related to the parts dyed green. The analysis of cotton dyed by the traditional Japanese method shows the similar results. It means that both colors in the NABESHIMA-DANTSU carpets were dyed by the traditional Japanese method which uses natural dyes. From literature documentation, it is considered that synthetic dyes were mainly used during the Taisho era. The present result shows that natural dyes might have been used in the Taisho era. In this research the PIXE method has proved to be very effective for the analysis of dyeing methods.

The knowledge of the intracellular distribution of biological relevant metals is important to understand their mechanisms of action in cells, either for physiological, toxicological or pathological processes. However, the direct detection of trace metals in single cells is a challenging task that requires sophisticated analytical developments. The combination of micro-PIXE with RBS and STIM (Scanning Transmission Ion Microscopy) allows the quantitative determination of trace metal content within sub-cellular compartments. The application of STIM analysis provides high spatial resolution imaging (< 200 nm) and excellent mass sensitivity (< 0.1 ng). Application of the STIM-PIXE-RBS methodology is absolutely needed when organic mass loss appears during PIXE-RBS irradiation. This combination of STIM-PIXE-RBS provides fully quantitative determination of trace element content, expressed in μg/g, which is a quite unique capability for micro-PIXE compared to other micro-analytical methods such as the electron and synchrotron x-ray fluorescence. Examples of micro-PIXE studies for sub-cellular imaging of trace elements in various fields of interest will be presented: in patho-physiology of trace elements involved in neurodegenerative diseases such as Parkinson's disease, and in toxicology of metals such as cobalt.

We have been developing microcapsules that release anticancer drug with response to radiation. We attempted to decrease the diameter of capsules. Then, two categories were tested in VIVO in C3He mice: (1) the antitumor effect in combination with radiation and subcutaneously injected nanocapsules, (2) the kidnetics of nanocapsules when they were injected intravenously.

Microcapsules were produced by spraying a mixture of 3.0 % hyaluronic acid, 2.0 % alginate, 3.0 % H₂O₂, and 0.3 mmol carboplatin (Pt containing anticancer drug) onto a mixture of vibrated 0.3 mol FeCl₂ and 0.15 mol CaCl₂. The antitumor effect was measured by measuring tumor diameter every day. The kinetics of microcapsules were expressed as the numbers of capsules in 5 views (25 × 25 μm) of micro PIXE camera and Pt concentration of quantiative PIXE.

The generated microcapsules 752 ± 64 nm, which were significantly downsized relative to previous capsules. The accumulations of capsules in lungs, liver, and kidneys were decreased by downsizing, whereas those of tumors were increased. By adjusting Pt concentration in tumor, there were no significant differences in antitumor effect between not downsized and downsized microcapsules with combination with radiation.

Decreased trapping of downsized microcapsules to lungs, liver, and kidneys, also increased trapping in tumors will lead to new targeted chemoradiotherapy via intravenous injection of microcapsules.

Neurodegenerative disorders are accompanied by altered compositions of metals that may convey some information about the health and possibly metabolic state of neurons. Here we opted for PIXE technique to perform a spatially-resolved elemental analysis of intracellular space of individual neurons. Primarily, we measured element distribution within Purkinje cells (PC) of normal and Lurcher (Lc/+) mutant mice to detect any anomalies in concentrations of individual elements attributable to cell death. Lc/+ mutant mice provide an excellent animal model for time-course of excitotoxic cell death. PCs, some with autofluorescence, were scanned with a proton beam to record their X-ray emission and RBS spectra and to construct 2D-concentration maps of individual elements. PCs with auto-fluorescence, presumed to be either already dead or moribund, showed elevated concentrations of Cu, Fe, and Zn, when compared to healthy PCs. In conclusion, excitotoxic mode of death, as observed in the moribund PCs of Lc/+ cerebellum, may activate enzymatic processes, manifested as increased intracellular concentrations of Cu and Zn that are possibly constituents of some metalloenzyme complexes.

In this study, we applied ML-EM (maximum likelihood expectation maximization) iterative algorithm and STIM-CT to a three dimension imaging technique of PIXE -CT for cellular analysis using 3 MeV proton microbeam with a diameter of 1 μm at TIARA (Takasaki Ion Accelerators for Advanced Radiation Application). The algorithm had been applied to tomography such as SPECT (Single Photon Emission Computed Tomography). It is also possible and suitable to apply the algorithm to PIXE-CT because the algorithm can be used to project images taking into account errors due to rare events. Energy loss of incident particles and absorption of X-rays, however, affect quantitative values dramatically in the case of PIXE -CT. We estimated those effects from density distribution of major elements measured by STIM-CT in this work. In order to show the appropriateness of this method, X-ray yield and absorption were calculated using density distribution of two-dimensional Shepp phantom. The PIXE-CT experiments were carried out using a dried unicellulate as a test sample placed on an automatic rotation stage, which made a full turn by rotating 360° at each step of 18° in vacuum. The results of those simulation and experiments have proved that this method is effective.

Quantitative three dimensional analysis is possible, in principle, by PIXE tomography. But, the inherent problems in quantitation, restrictions on the sample geometry and preparation, and specimen damage due to high fluences make this method unsuitable for many biological samples. The specimen under investigation, a murine artery, was around a millimeter in diameter and the induced atherosclerotic lesion was spread few hundreds of micrometers across the length of the artery. Since no tomographic experiments were possible, we chose to do the 3D quantitative analysis by means of PIXE Stacking. Herein, thin serial sections of the specimen are prepared and measured by conventional ion beam techniques. The resultant two dimensional quantitative element maps are stacked and aligned to reconstruct a quantitative volume of the specimen. Although the reconstructed dimension has poorer spatial resolution as compared with the measured dimensions, new information can still be gained from it. The three dimensional element distribution of the atherosclerotic lesion shows calcification on the outer surface of the artery, which otherwise would not have been easily visible in the two dimensional analysis.

Hair mineral content has become a useful biomarker to measure exposure to elements both safe and unsafe. To promote the use of hair mineral volumes in clinical practice, it would seem crucial to first determine their normal ranges by the statistical analysis of hair minerals sampled from a large healthy population. This paper used Proton Induced X-ray emissions (PIXE) to measure mineral concentrations in the hair of 842 mother-infant pairs. The data were then statistically analyzed to determine their normal ranges and categorized into 4 groups based on distributional characteristics. Intra-individual variations are also identified and discussed with regard to risk analysis.

Melanoma is a serious skin cancer that, if found and treated in its early stages can be cured before it gets invasive and develops metastasis. The incidence of this disease has steadily increased in white populations throughout the world in the last decades. Although the basis for this rise is incompletely understood, it is known that solar exposure and genetic factors are important precursors of melanoma. Nowadays, some studies are correlating some trace elements in blood and tissues with the disease. In this work, trace element concentrations in blood serum of patients with melanoma where measured by PIXE (Particle Induced X-ray Emission) to verify if there is a link between the concentrations of elements in the blood serum and melanoma. If the hypothesis is proven, elements in the blood serum could also be used as markers for melanoma. The samples were collected in the São Paulo Hospital and analyzed by PIXE after an internal standard addition. Concentrations of Chlorine (Cl), Potassium (K), Calcium (Ca), Copper (Cu), Zinc (Zn) and Bromine (Br) were measured in serum of 30 patients with melanoma and 116 control individuals. The elemental concentrations were calculated relative to an internal Gallium standard. The accuracy of the method was verified analyzing an IAEA A-13 Blood (International Atomic Energy Agency) and a QMEQAS08S-06 serum (National Institute of Public Health). The results of this work showed no significant difference between melanoma and control group (independent t-test and U-test, p = 0.05).

Naturally shed deciduous teeth are potentially useful as a biomarker of environmental exposure. To assess the prenatal environment of child, we tried to present the neonatal line on the elemental maps and investigate the trace elements in pre- and post-natally formed tooth enamel using micro-PIXE. Generally, the neonatal line is observed more clearly in the tooth from child who has some difficulties at birth. In this study, five deciduous teeth from five children with developmental disorders were used for analysis. Seven trace elements (Na, Mg, Si, Cl, Fe, Zn, and Sr) were detected in enamel of all five teeth. The line, it was thought neonatal line, was observed on the elemental map of Ca and P in the tooth from the child with serious birth complications. In order to compare the elemental concentration between pre- and post-natal enamel, concentration variation of elements were projected along the line perpendicular to the neonatal line. Lower Ca concentration in prenatal enamel was observed. By tracing the location of neonatal line on the other elemental maps, the concentrations of detected trace elements were compared in the same way. The differences of concentration of these trace elements between pre- and post-natal enamel were not clear because of much statistic variation. We could determine the trace elemental profiles and concentrations around the neonatal line in the enamel from the child with serious birth complications.

The present study examined the index of absorption of trace element (Fe, Cu, and Zn) in different semi-solid nourishment medicines. Various mineral compositions were administered to 7-week-old male rats and semi-solid nourishment medicine from three companies, each using a different gelling agent, were orally administered for two weeks (5 per group). Five rats that were that were fed the standard diet were used as a control group. The rats' excrement excreted after the administration the nutritional supplement was gathered, and the density of trace elements was measured by the PIXE method. The trace element value of each semi-solid nourishment medicine and the standard diet were measured before the experiment, and the intake of trace elements was calculated based on these values. The amount of gut absorption was subtracted from the amount excreted. The groups were compared by the index of absorption.

The use of the medicinal herbs for curing disease has been documented in history of all civilizations. With introduction of scientific procedures, researchers isolated active constituents of the medicinal herbs and after testing, some were found to be therapeutically active. Trace elements are important constituents of active principles of medicinal plants which affect the human body. The aim of this study was to determine qualitatively and quantitatively trace elements in these plants and their medicinal roles in the human body. Analysis of medicinal plants of various biological activities, commonly used in Northern India, was carried out using PIXE technique. Plant samples were collected from Chandigarh (India), which is located at the foothills of the Shivalik ranges, which form a part of the fragile Himalayan ecosystem. PIXE measurements were carried out using 2.4 MeV collimated protons from the 3 MV Tandetron (accelerator) of NCCCM, Hyderabad, India. Various elements namely S, Cl, K, Ca, Ti, V, Mn, Fe, Ni, Cu, Zn, Se etc. were detected with different concentrations. Many of these elements play significant roles in human metabolism and are very important with regards to life processes in man.

The New Zealand capability in Ion Beam Analysis of air particulate samples has been upgraded in recent years. The main equipment change has been the introduction of the ability to analyse samples taken using the Streaker (PIXE International Corporation) sampling system. This is an automated sampler which allows for great flexibility in monitoring programmes by collecting particulates for up to about 70 sampling periods which can range in collection times from seconds to many hours. The IBA analysis for hydrogen on standard filters and for PIXE multi-elemental analysis of the Streaker filters has also been studied with a view to optimising analytical methods.

This study was conducted to investigate the relationships between arsenic (As) levels in human hair and demographic factors on As accumulation in humans. Hair samples of 619 subjects (383 females and 236 males), including 390 confirmed arsenicosis patients, 11 fish and six vegetable samples were analyzed using the Proton Induced X-ray Emission (PIXE) method. The results revealed that As in hair accumulates in different patterns for males and females in accordance with age. Within patient groups, male patients accumulated higher amounts of As than female patients. For all individuals, middle aged females accumulated higher As amounts in hair than children, adolescents and females over 50 years old, while children, adolescents and males over 50 accumulated higher amounts of As than middle aged males in both villages. Surprisingly, high levels of As concentrations were found in hair samples of those living near safe drinking water in both villages, irrespective of age and sex. There were weak positive correlations between hair As levels and groundwater As levels in both villages. Furthermore, toxic levels of As were found in different kinds of food products. Taken together, these findings demonstrate that As accumulation in hair is dependent not only on water contamination, but also on food contamination.

The tidelands (tidal flats) of the seaside district of Tohoku, Japan, which play an important role in maintaining the diversity of the marine ecosystem, were almost completely destroyed by the massive tsunami that occurred on March 11, 2011. The tsunami also brought large quantities of contaminated sludge from the bottom of the sea to the coastal lands including the tidelands. In this study, we collected sludge samples from three tidelands: the Tsugaruishi estuary tideland (Iwate pref.), the Orikasa estuary tideland (Iwate pref.), and the Gamou tideland (Miyagi pref.). We then analyzed the samples using PIXE in accordance with a powdered-internal-standard method that we developed. In order to investigate the effects of the contaminated sludge on the ecosystem, we gathered and analyzed various kinds of wild plants and seaweed. We found that the tidelands are contaminated with heavy elements, such as arsenic, lead, zirconium, and barium, although the contamination is less serious in the vicinity of the beach.

The method, which was developed by our group, enables us to perform quantitative analysis of living plants. It has been applied to investigate the transport of heavy elements such as germanium, gallium, bromine and arsenic in plants. These heavy elements are transported to the leaf through vascular vessel, and changes of their concentration with elapsed time after absorption could be clearly observed. It was confirmed that the movement depends on elements, on the manner of absorption and on the states of plant growth. In addition to the movement of supplied elements, some elements in the plant show interesting changes in response to proton irradiation. It was found that the method is quite effective for examining elemental movement in living plants.

Rocks and melt inclusions (MI) from 11 volcanic centers of the Kermadec-Tofua arc, in the South West Pacific, were petrographically studied prior to chemical analysis under the ion beam. The abundance of MI with daughter minerals are volcano-specific with the most abundant found in "U", Putoto, and Hinepuia volcanoes where >50% of MI contain daughter minerals. The B, Li, Cl and S contents in MI generally increase with the silica content of the rock. Fe, Ni, Mn, Cu and Zn are common in MI of all rock types but Mo, Hg and Cu have the highest concentrations in dacite-rhyodacites. The highest concentrations of B, Ti, V, Fe, Co and Mo occur in plagioclase MI; S, Ni, Ge and Hg in pyroxene MI; Cl and Li in quartz MI; and Cu, Zn and M in hornblende MI. Different ore-forming components in volcanic rocks can be correlated with rock composition, Cl/S and B/S of the melts, the presence and abundance of mineral sinks for various elements and the occurrence of hydrothermally altered rock at depth and on the seafloor.

Due to increased energy demands from its rapidly growing economy and population, ambient air in Ulaanbaatar, the capital city of Mongolia contains some of the highest reported air particulate matter (APM) concentrations in the world. The purpose of this study is to identify major APM sources. Source apportionment is an elegant and effective way to establish baseline data for mitigation strategies that focus on reducing APM pollution. The Nuclear Research Centre at the National University of Mongolia has been conducting APM pollution studies in Ulaanbaatar since 2004. Results presented here are based on a sampling campaign from June 2008 to May 2009 at two sites in Ulaanbaatar. APM samples were collected on polycarbonate filter, in two size fractions, fine (PM_2.5) and coarse (PM_10-2.5) particulate matter. Ion beam analysis provided the elemental concentration values and receptor modeling was used to determine the sources contributing to the particulate matter pollution. The results show that the main sources of PM pollution are soil, motor vehicles, coal and wood combustion, with varying contributing amounts at each site. Source contributions to PM_2.5 at a residential site were found to be: soil 47%, coal combustion 35%, motor vehicles/road dust 13% and biomass burning 4%. At the residential site it was found that the primary source contributors to PM_10-2.5 were soil 71%, coal combustion 10%, and motor vehicles/road dust 19%.Source contributions to PM_2.5 at a non-residential site were found to be: coal combustion 92%, motor vehicles/road dust 3%, soil 3% and biomass burning 2%. At the non-residential site it was found that the primary source contributors to PM_10-2.5 were: soil 92%, motor vehicle/road dust 5% and coal combustion 3%.

Sr is an indicator used in studies on fish migration. In this study, the Sr profiles of ridges, which are growth lines in fish scales, in Sakhalin taimen (Hucho perryi) were examined by micro-PIXE analysis. Sakhalin taimen were reared under freshwater conditions for six months. The ridges that formed during the rearing experiment were subjected to PIXE spot analysis. This analysis was performed in a 5 X 5 μm² area in the center region of each ridge of the scale section, and the Sr levels were calculated using the thin-section standard. The mean Sr concentration in the ridges was 428± 48 μg/g. The quantitative PIXE spot analysis successfully provided Sr profiles for the scale corresponding to ridge formation.

As a part that, an epidemiological study on the effects of physicochemical characterization of airborne particulate matter (PM) and ozone on asthma attacks, we carried out size-resolved sampling of PM in Himeji City, and elemental and ionic composition analyses of the PM sample. Size-resolved PM was collected using a 3-stage NLAS impactor (Tokyo Dylec Co., Ltd.; particle cut size at sampling stages was 10, 2.5 and 1.0 μm for a flow rate of 3 L/min) with a one-week base sampling interval, and the PM sampling was begun in November, 2009. Concentrations of several elemental and ionic species in the PM sample were determined by PIXE and ion chromatography analysis, respectively. The research results are important for the physicochemical characterization of PM in atmosphere, enabling detailed analysis of the year-round behavior. Of particular note, is that the PM₁₀ was mainly NO₃^- and SO₄^2- and PM_2.5 was only SO₄^2-. This is believed to suggest the different formation processes of NO³_- and SO₄^2-.

Pollution events are at times difficult to detect because of continuous river flow. Changes in the chemical composition of the water are incorporated into the matrix of fish scales as growth occurs, and, as a result, pollutants in the water may be identified by the analysis of fish scales. The structure of growth patterns on fish scales is characteristically anisotropic. The respective growth patterns appear to be intermittent, convergent, divergent, continuous or discontinuous probably depending on the conditions. Because of anisotropy, fish-scale growth can be described in a mathematical discrete model based on fuzzy terms. The incremental band area was fitted with the saddle-type asymmetric sigmoidal function. There is no significant difference between the composition of keratin in the annuli and the chemical composition of keratin in the circuli. This indicates that there is not acute chemical composition demarcation between the area of the circulus and the incremental band. In the regions of the circuli structure, disruption occurred and the incremental band area is smaller. However, the acute chemical composition demarcation still exists.

In salt farms of Thailand, saline ground water is pumped up and then solar-evaporated to produce salt for commercial purpose. However, when they continue to precipitate salt in the same pools, the product is stained yellow or brown in color. In order to recover only white salt, workers cut trees and create a new pool next to the old one. Due to this practice, year by year, salt-farming area loses vegetation cover and expands barren section of salt damage. In order to understand the changes of in salt grains, salt was collected and measured by PIXE. The result indicates that manganese is clearly responsible for the coloring, and possibly also irons. This information is expected to base the discussion to stop deforestation in the salt-damaged area.

Growth environment of plants was investigated by analyzing the elemental concentration in leaves of the plants. Camellia was selected as the sample and the leaves of the camellias were collected from Miyagi and Chiba prefectures. The species of elements and their concentrations in the leaves were measured by the in-air PIXE system at Tohoku University. More than 10 elements were detected from the leaves. The concentrations of Mn, Fe, and Rb in the leaves were strongly affected by the place where the tree grew. On the other hand, the concentration of P, S, K, and Ca were less affected by the place of the tree. The determination of the place of the tree was also performed by evaluating the similarity of the elemental concentration in the leaves quantitatively. The difference due to the place was clearly identified and the sampling place was successfully determined by using the elemental concentrations in the leaves.

An extensive investigation, aimed to study the fine fraction of airborne particulate matter (FAPM) in the Mexico City Metropolitan Area (MCMA), started in 2003, after the FAPM sampling network of the Environmental Secretariat of the Federal District Government (Secretaría del Medio Ambiente del Gobierno del Distrito Federal, SMA-GDF) was put into operation. Formerly, several research institutions in Mexico, in collaboration with the local government, made continuous efforts during the last two decades, in order to improve air quality in the MCMA. Samples have been collected using US-EPA designated samplers, following the same agency protocols. In this study, 922 samples were analyzed by PIXE in order to determine the elemental concentrations (ng/m³) of the FAPM. The samples were collected every three days by the Atmospheric Sampling Network (Red Automática de Monitoreo Atmosférico, RAMA) of the SMA-GDF, starting by the end of 2003 and along 2004 on three sites, and during the whole 2005 to the beginning of 2006 in seven stations, taking samples every six days during this last stage. The sample collection has continued up to date at the latter pace. The results obtained have allowed determining the sulfur (S) spatial distribution over the area, showing a reasonable uniformity in space, but well marked time variability. The S spatial distribution has also showed similar patterns between equivalent seasons from year to year, although not a strict periodicity. Compared to other elements found consistently in the samples, S is mainly distributed over the area by a large amount of mobile (mainly transportation) sources, fairly distributed over it, while other elements come from fixed sources located at industrial or urban areas. Comparisons were also made among the sampling sites, and among the three climatic seasons (drycold, dry-hot and rain) from year to year. Correlations between temporal variations of pairs of sampling sites were also calculated for S and other elements, in order to support these conclusions.

As part of a wide research project aimed to understand and eventually control atmospheric pollution in the Mexico City Metropolitan Area (MCMA), the Secretaría del Medio Ambiente del Gobierno del Distrito Federal (SMA-GDF) operates, since 2003, an automated sampling network of fine airborne particulate matter (FAPM). In this study, the samples collected simultaneously in three sampling sites during years 2003–2004, and those collected (simultaneously) in seven sites during the whole of 2005 and the first three months of 2006, have been analyzed using the PIXE technique. The results have provided ample databases of elemental concentrations (ng/m³) of 13 elements, consistently detected in the samples. As it is well known, Mexico City and its conurbation has been ranked as one of the most densely populated areas in the world, enduring high levels of several pollutants such as PM_2.5 fine particles (≤ 2.5 μm) and sulfates among others, which diminish air quality, visibility and endanger the health of the population. According to the emission inventories of the SMA-GDF, around eight thousand tons of SO₂ are emitted to the atmosphere in the MCMA every year. Despite continuous efforts of the local authorities aimed to reduce SO₂ emissions, S elemental concentrations determined in the PM_2.5 samples collected by the fine particle sampling network still show significant levels of this element. Since sulfur compounds, particularly sulfates, are among the most important pollutants affecting the atmosphere, it is compulsory to evaluate its presence and concentrations. As it is has been pointed out by several authors, the ratio of sulfate content to S elemental content in FAPM, such as that determined by PIXE, is fairly constant (approximately three). Using this result, sulfate concentrations were calculated, and these were found in very good agreement with previous experimental results.

Elemental distributions of Al, Si, P, S, K, Ca in tea leaves were measured using micro-beam PIXE. In mature tea leaf, aluminum localized eccentrically in the upper epidermis and silicon showed quite similar spatial distribution. It was found that the aluminum concentration and spatial distribution changeed with the growth period of the tea leaf. In younger leaves of two and four month, aluminum showed relatively low concentration compared with the matured one and distributed in mesophyll cell uniformly. In five month leaf, aluminum concentration became higher and the distribution began to localize in upper surface

A gigantic tsunami following Tohoku-Earthquake Disaster brought a large amount of sludge, which originated from the sediments pilling upon the bottom of the sea to the residential areas. As it is anticipated that the sludge contains a large amount of heavy toxic elements, its influence on the health of the suffered people will become a problem. In the present study, 72 sludge samples were taken from the stricken areas by the tsunami over the wide area; (Aomori, Iwate and Miyagi prefectures). These samples were treated on the basis of a powdered-internal-standard method and analyzed by means of PIXE with a specially-designed absorber. It was found that the sludge contains much amount of heavy elements such as arsenic, lead, zirconium, barium etc. in comparison with those in soils collected in the inland district of Iwate prefecture. Furthermore, 16 plant samples were gathered in the estuary area, on which the sludge deposited, and analyzed in order to evaluate the effect of the sludge on the ecosystem. These results were compared with those for 45 plant samples collected in the inland district of Iwate, Miyagi and Fukushima prefectures. It was found that these plants contain lager amount of heavy elements in comparison with those in the inland plants.