Map of Selenium Content in Soil in Japan

We present a new selenium (Se) map of Japan in more detail than in our previous report (J. Health Sci., 42, 360–366). It contains 150 measured points, especially in the northeast of Japan. In the new sampling points, we did not find high Se levels and most of the measurements were generally at values below 1 mg/ kg. In the Se map of Japan, there are two particularly high measurements, at Mt. Zao (10 mg/kg) and Tateyama Murodo Jigokudani (148 mg/kg). These two areas are the origin of a minor branch of the Abukuma River and the Jouganji River, respectively. We also analyzed the Se levels near two major copper mines, Asio and Besshi. We detected high Se content in rocks at both copper mines and an average Se level in soil from the area near the Asio copper mine. The Se level in soil at Besshi was slightly higher than that at the area near the Asio copper mine. We also measured the Se levels of some pyrites in Japan. The Se levels of most pyrites were some ten mg/kg higher than the general Se level in soil. This study provides information about the fundamental background values of Se levels in soil and rocks to correlate with Se pollution if it occurs in the future.