In this study, concentrations of heavy metals and anions of natural origin were investigated using boring core obtained from the north bank of the Shin-yodogawa River in the northern part of Osaka City. A leaching test and a content test in compliance with Soil Contamination Countermeasures Law in Japan were applied. The leaching test is a method by which soil in ten times its volume of water is shaken for 6 hours, and considers the risk of ingestion of groundwater contaminated by hazardous substances eluted from contaminated soil. The content test is the method of eluting hazardous substances from 6 g of soil by shaking the sample in 200 mL of 1 mol/L hydrochloric acid for 2 hours, and considers the risk of the direct ingestion of contaminated soil. Concentrations of heavy metals obtained by the content test were lower than stipulated in the Japanese regulations, while some samples showed higher concentrations than stipulated in the regulations when using the leaching test. Metal concentrations were also observed by a microwave extraction method (MEM), which approached those of the total content analysis. The relationships between ratios of leaching amounts to the concentrations obtained by MEM and solution pH were used to discuss leaching characteristics. Because there were good correlations among concentrations of heavy metals and anions obtained by the leaching test, boron concentration could also be estimated from Cl- concentration, and F- concentration could be estimated from both concentrations of SO42- and Ca. There is a possibility that total amounts of Pb and Cr of natural origin in soil could be estimated using relationships with total amounts of other metals such as Ni, V, Mn, Zn and Mg, because their concentrations obtained by MEM showed good correlations.
After the severe accident at the Fukushima-1 Nuclear Power Plant in March 2011, radioactive contamination of food has become a matter of serious concern in Japan. There is considerable information about radioactive iodine and cesium, but little is known about uranium contamination. We determined uranium content in spinach by the Japanese official method (Manual on Radiation Measurement of Food in Emergency Situations). In the preliminary study, we confirmed that the use of a microwave digestion system for preparing the test solution of spinach could shorten the testing time and give acceptable results. The manual recommends the use of two elements (Tl and Bi) as internal standards for measurement of uranium by ICP-MS. We found that Tl was more suitable than Bi to quantify trace amounts of uranium in spinach. However, it was necessary to determine Tl or Bi concentrations in the sample before analysis, since some samples of spinach contained significant amounts of these elements. The uranium contents of 9 spinach samples bought in April and May 2011 were less than 10 μg/kg, which are very low compared to the provisional regulatory limit in Japan.
Lead isotopic analyses of road sediments and traffic-related substances, such as asphalt, traffic paint, automobile tires, wheel balance weights and automobile exhaust, have been carried out to determine the sources of lead pollution in road runoff. Smaller particles in road sediments contained a higher lead concentration and showed the same lead isotopic composition as road runoff; therefore, lead in road runoff was mainly attributed to minute particles (<53 μm) in the sediments. Because yellow traffic paint was found to be rich in lead and showed a similar lead isotopic composition to road runoff, it would be considered as the source of lead pollution on the condition that it was used near the site. White traffic paint and automobile tires did not contribute to lead runoff because of their low lead concentration and different lead isotopic composition. The lead isotope ratios in wheel balance weights fell within almost the same range as that of road runoff; therefore, wheel weights were determined as a major source of traffic-related lead runoff.
