Search

We developed mini step samplers with low manufacturing and running costs for application in multi-site air-pollution monitoring. The miniaturization of the sampler was achieved by reducing the suction nozzle size. We tested the samplers with suction nozzle diameters of 2 and 4 mm through simultaneous exposure in the same site. Elemental concentrations of aerosol collected by these samplers were consistent within ±20% during comparison and the sample uniformity did not differ significantly. Sampling with small suction nozzle did not adversely affect aerosol collection. Aerosol samples were collected simultaneously at two sites in our laboratory and in the hall outside for 3 days and analyzed subsequently by PIXE. The time variation of elemental concentrations was high during daytime and low at night time and also during the weekend. Elemental concentrations in the hall were always higher than those in the laboratory. In our laboratory, we change shoes at the entrance and therefore, elemental concentrations inside the lab are lower than in the hall. In a second field experiment, we carried out simultaneous multi-site aerosol sampling during two periods in correlation with meteorological data (wind direction and velocity). It was observed that elemental concentrations of some soil origin elements changed periodically. On the other hand, the concentration of Cu and Zn showed irregular concentration spikes whose pattern showed a variation with the sites. Analysis using the data of wind directions showed that Cu had been transported to the sites from northeasterly direction and that the concentration of Zn was influenced by two big factories nearby. In conclusion, it has been demonstrated that the multi-site sampling system combined with meteorological data is well suited to identify sources of pollution.

The groundwater pollution by arsenic in Bangladesh causes a serious problem for millions of people who are exposed to poisoning by this toxic element. In an attempt to evaluate the extent of arsenic poisoning, hair samples of people living in Pabna district were collected. The hair samples were analyzed using Proton Induced X-ray Emission (PIXE) through exciting the atoms of a specimen so that their intensities can be converted into elemental concentrations in the specimen. The elements present in the specimen are identified by the corresponding X-ray energies and their concentrations are deduced from the X-ray intensities. The results from hair samples indicate substantially higher level of arsenic than those demarcated as toxic levels, in people from member families both affected and non-affected by poisoning. We correlate it with exceedingly high arsenic concentration in drinking water far above the permissible limit. The analytical results are compared with the results of arsenic and other elemental analysis of 160 Bangladeshi hair samples with that of 250 Japanese samples. The results show markedly higher levels of arsenic, manganese, iron and lead where the latter three elements show a positive relation with arsenic in the case of Bangladeshi as compared to the samples from Japan. On the other hand, selenium concentrations show very low level in the Bangladeshi samples compared to Japanese, displaying an inverse relationship with arsenic. The mechanism of arsenic in relation to other elements in the human body needs further investigation. The preliminary results call for detailed experimental and epidemiological studies to further characterize these aspects.

Tailings from an indigenous mining community were analyzed by PIXE to study the residual amount of gold and to check the relative increase in mercury content after the mineral dressing. The result showed that gold is sometimes left in the tailings at ore-grade concentration up to 30 ppm, and that relative mercury content is not increasing drastically. Since the tailings are trade target in the local community, it would be necessary for stakeholders to have a common and fair facility where they can assay gold content of the tailing at regular interval.

In order to address global environmental issues, a standard-free method developed by ourselves has been successfully applied to various kinds of bio-samples. Especially, a method for untreated hairs has been applied in many polluted areas to study human exposure to toxic elements. In addition to hair, nail is expected to give us valuable information about human exposure to toxic elements. However, the analysis requires relatively large amounts of samples and laborious sample preparation techniques which necessitate internal standards. In this work, we have developed a quantitative method for untreated human-nail analysis based on the standard-free method. It requires neither large amounts of nails nor complicated target preparation procedure. Furthermore, it is perfectly free from any ambiguity in target preparation such as volatilization of certain elements and contamination of the sample during chemical ashing. The optimum conditions of irradiating nail samples are established, and accuracy and reproducibility of the present method are confirmed. It is found that ultrasonic washing in distilled water is effective for many nail samples preventing the loss of elements from the sample. It is also found that elemental concentration in nails strongly depends on their sampling positions.

A PIXE analysis was performed at Nishina Memorial Cyclotron Center (NMCC) for some leaf and ash samples from bottom of a waste pond at the Fankou Pb-Zn mine, Guangdong, China. The ash is the product after burning "Luzhu" that is planted by the mine for the environmental cleaning purpose in the waste pond. The PIXE detected high level of zinc and lead for both of the samples. As Fankou is one of the largest Pb-Zn producer in Asia, careful and urgent treatment is necessary for the deposited ash in the pond. This analysis was performed due to a request of analysis of the Fankou mine to promote environmental protection of the area.

Non-radioactive liquid waste generated in the Kaya Memorial Takizawa Laboratory was analyzed using the PIXE system established at the Nishina Memorial Cyclotron Center. Samples of the liquid waste were collected at several stages of the non-radioactive liquid waste purifying process. A simple sample preparation method for liquid sample was adopted. Liquid sample was dropped and dried directly on the backing film after adding the internal standard element, which produced appropriate targets to be analyzed by PIXE. Sodium, silicon, sulfur, chlorine, potassium, calcium, iron and so on in the liquid sample were detected. The PIXE method used in this study showed outstanding properties for analyzing the liquid sample.

Nineteen samples of fossil wood (from Holocene to Miocene in age) were examined for their inorganic constituents by PIXE analysis. The results showed the presence of 28 elements including Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, As, Se, Br, Rb, Sr, Zr, Nb, Mo and Ag. Fossil woods were characterized by their high content of S (max 16,000 μg/g) and Fe (max 8700 μg/g) in striking contrast with recent woods. It was assumed that sulfides such as pyrite or marcasite observed in coal were adventitiously formed by sulfide infiltration from the sediments during long geologic time after wood had been buried into bed, and that the impregnation might be related to the humification of wood.

A method has been developed and tested for PIXE analysis of soluble and insoluble constituents in a variety of water samples in our surroundings. Insoluble components were filtered on a Nuclepore filter of 0.4-μm pores. For soluble fractions, a target of major components was made from a 0.15-ml filtrate evaporated on a user-made polycarbonate film, and in turn heavy metals in trace amounts were preconcentrated in a PIXE-target through the use of a combination of dibenzyldithiocarbamate-chelation with subsequent condensation into dibenzylidene-D-sorbitol gels. These three kinds of targets were analyzed with a PIXE system of 3-MeV proton beams. The widespread concentrations (several tenths of ppb to a few tens of ppm) of ~24 elements from Na to Pb were determined simultaneously in a precision sufficient to reveal the elemental distribution between the soluble and insoluble fractions of various aqueous samples such as river water, rain water and water leaking from disposal sites of industrial wastes. Hence, the methodology for preparing three types of targets promotes the PIXE analysis to a truly effective means for monitoring a water-pollution problem in our surroundings.

PIXE, Particle Induced X-ray Emission, is a Powerful, multi-elemental analysis method which has many distinguishing features and has been used in varies research fields. Recently the method of applying baby cyclotrons for nuclear medicine to PIXE has been developed. This enables us to study biomedical phenomena from the physical point of view. Mouse bone marrow stromal cells were transferred bacterial β -galactosidase gene (LacZ gene) by murine retroviral vectors. Analysis of the bone marrow stromal cells with the LacZ gene by PIXE revealed remarkable changes of intracellular trace elements compared with the normal control cells. These results indicate that gene transfer by retroviral vectors may bring about a dynamic change of intracellular circumstances of the target cell.

Since our laboratory was established in 1990, we have developed several computer programs for the data handling and analysis: programs for converting binary or ASCII format of spectra and arrangement of data files, for X-ray spectrum analysis, for determining the efficiency of a Si(Li) detector, for determining the transmission curve of an X-ray absorber, and for calculating ionization cross sections. The latter threes are used for obtaining physical quantities which are required for determining quantitative concentrations of elements and must be prepared individually for each experimental conditions. These five computer programs have all been developed for two types of personal computers and some of them have already been distributed and widely used in Japan.

Vascular cell adhesion molecule-1 (VCAM-1) is transiently expressed on vascular endothelial cells in response to cytokines. It plays a major role in the adhesion of leucocytes to the endothelium by interaction with its ligand VLA-4, a member of the β1 integrin family. We measured the serum concentration of the soluble VCAM-1 (sVCAM-1) in 114 patients with acute myocardial infarction (AMI) and 37 normal controls by enzyme-linked immunoassay in comparison with trace element concentration. sVCAM-1 levels were markedly higher ( mean ± SD =833.2 ± 328.9 ng/ml ) in the sera of patients with AMI than in normal controls ( mean ± SD = 549.5 ± 188.8 ng/ml , p

Vascular cell adhesion molecule-1 (VCAM-1) is transiently expressed on vascular endothelial cells in response to cytokines. It plays a major role in the adhesion of leucocytes to the endothelium by interaction with its ligand VLA-4, a member of the β1 integrin family. We measured the serum concentration of the soluble VCAM-1 (sVCAM-1) in 114 patients with acute myocardial infarction (AMI) and 37 normal controls by enzyme-linked immunoassay in comparison with trace element concentration. sVCAM-1 levels were markedly higher (mean± SD=833.2±328.9 ng/ml) in the sera of patients with AMI than in normal controls (mean±SD= 549.5±188.8 ng/ml, p

Zn-DTPA was injected intraperitoneally into rats (30 µmol/kg) with a single dose or a daily dose for 10 consecutive days. Urine samples were collected for 24 hours after the single injection and tissue samples were excised 20 hours after the final of the consecutive injections. Elements in these samples were analyzed by PIXE. Zn-DTPA raised the urinary concentration of zinc and copper, and their urinary losses caused by Zn-DTPA were estimated to be 1.9 and 0.01 mg/30μmol Zn-DTPA, respectively. The concentration of metals in the liver, kidneys, brain and femurs remained unchanged. These results suggest that almost all of Zn-DTPA is excreted into the urine without replacement with other metals, and so this chelating agent may not induce any deficiencies of essential metals when animals are treated with a dose of 30 µmol/kg per day.