Heavy Metal Contamination in Urban Soils III Metal Status of Soil-Plant Systems in Parks and Arable Lands in Sakai, Osaka

摘要

In order to evaluate the recent state of environmental qualities of industrial city areas, especially in soil-plant systems, surveys on heavy metal contents in various urban soils and plants were conducted in 1977 and 1978. Sakai City in Osaka Prefecture, which has notable activities both in industry and agriculture, was chosen for this purpose. Five elements (Zn, Cu, Mn, Pb and Cd) in the soils of municipal parks, vegetable farms and rice paddy fields and in oleander leaves from the parks and several kinds of vegetable crops from the farms were determined over the wide city area. It was found that the metal accumulation in urban and suburban soils corresponding to city activities were the most remarkable in the case of zinc, and the similar patterns were also observed in other three metals, but the distribution of manganese was different from those of the other elements. Correlations between the heavy metal concentrations in the soils and plants were not clear reflecting the possible influences of various soil factors other than metal contents in soils. The manganese contents in the oleander leaves and park soils showed significant tendencies to increase in the former and to decrease in the latter with the soil acidity. The heavy metal contents in the vegetable varied widely except for carrot, and leaf vegetables contained higher levels of metals than root crops. As factors being concerned with the behavior of heavy metals in soil environments, the possibilities of alkalization observed recently in urban soils and of the increment of metals from deposits via air were discussed with the data.