Heavy Metal Contamination in Urban Soils I Zinc Accumulation Phenomenon in Urban Environments as Clues of Study Heavy Metal Contamination in Urban Soils I Zinc Accumulation Phenomenon in Urban Environments as Clues of Study

As an introduction of the continuing study on the heavy metal contamination in urban soils, zinc accumulation phenomenon observed in urban areas in south Osaka was reported. The survey of zinc concentration in soybean leaves taken in urban and suburban arable lands indicated its accumulation in a wide area. And a correlation between easy soluble zinc level in soils and leaf zinc content were shown. Zinc concentrations in suspended particles in air, falling dust and some water samples were checked, and the high levels of zinc were found also in them. In several city parks, significant higher concentrations of zinc and lead in surface than subsurface soils were found. The ratios of easily soluble to total zinc were markedly high in urban soils than rural soils. In Sakai, at sandy fields near the coast of Osaka Bay, where the rotation culture of vegetables prevailed, zinc accumulation in soils was notable among heavy metals. Where the renewal of sand as the vegetable field had been made at intervals, there was a significant increase in zinc contents from new sand to older sand materials. From the above data, it was considered that the zinc accumulation observed in the urban areas was a wide phenomenon through atmospheric pollution caused by zinc emission from various sources. The probability of emission sources of heavy metals in urban environments was discussed. With respect to the zinc contaminants, emissions from the melting of scrap in iron and steel producing factories, the wear of rubber tire occurred with motorization and the incineration of municipal wastes are regarded as the main sources.

As an introduction of the continuing study on the heavy metal contamination in urban soils, zinc accumulation phenomenon observed in urban areas in south Osaka was reported. The survey of zinc concentration in soybean leaves taken in urban and suburban arable lands indicated its accumulation in a wide area. And a correlation between easy soluble zinc level in soils and leaf zinc content were shown. Zinc concentrations in suspended particles in air, falling dust and some water samples were checked, and the high levels of zinc were found also in them. In several city parks, significant higher concentrations of zinc and lead in surface than subsurface soils were found. The ratios of easily soluble to total zinc were markedly high in urban soils than rural soils. In Sakai, at sandy fields near the coast of Osaka Bay, where the rotation culture of vegetables prevailed, zinc accumulation in soils was notable among heavy metals. Where the renewal of sand as the vegetable field had been made at intervals, there was a significant increase in zinc contents from new sand to older sand materials. From the above data, it was considered that the zinc accumulation observed in the urban areas was a wide phenomenon through atmospheric pollution caused by zinc emission from various sources. The probability of emission sources of heavy metals in urban environments was discussed. With respect to the zinc contaminants, emissions from the melting of scrap in iron and steel producing factories, the wear of rubber tire occurred with motorization and the incineration of municipal wastes are regarded as the main sources.