SPATIAL DISTRIBUTION OF AS IN URBAN AND PERI-URBAN SOILS OF THE CITY OF IASI (ROMANIA)

The arsenic in soil generally shows a high toxic potential. The soil enrichment with As can be related to various anthropogenic sources. The natural components of soils are responsible for the accumulation or release of potential toxic elements. The investigated area is placed in the northern part of Romania. The soil evolved from Sarmatian deposits, mainly consisting of argillaceous rocks. In the urban area of the city of Iasi the most important sources for As derive from air born particles of heating systems or metallurgic and ceramic activities. The agricultural soils from the peri-urban area are affected by intensive use of fertilizers and pesticides which disturb the natural As content. The soil samples were collected according to 500x500 m grid and from several soil profiles were located in peri-urban area. The As total content was analyzed by EDXRF with detection limit of 1.13 mg.kg(-1). The range of As concentration in urban area is 2.0-30.7 mg.kg(-1), while in peri-urban soil the concentration range is 2-19 mg.kg(-1). In case of soil profiles the mass balance coefficient reveals the As trend to accumulate in the upper layer (0-40 cm). This behavior is related to the As affinity for Fe and Mn oxides. The As distribution in surface soil was performed by GIS method in order to emphasize the contamination points and the topography and climatic factor influences upon As migration. According to these spatial representation, the southern part of the city present a higher As enrichment as a consequence of industrial area and dominant NW wind direction. In the peri-urban agriculture lands, the As enrichment occurs in the vineyard areas.