PSEUDOTOTAL CONTENTS OF NICKEL AND CHROMIUM IN AGRICULTURAL SOILS OF NORTHERN VOJVODINA PROVINCE, SERBIA

The Vojvodina Province in northern Serbia is known for its intensive field crops production. The Province comprises several political, geographic and of production entities. This paper presents the results of the research conducted in northern Vojvodina - northern Backa and northern Banat within the national project no. TR31072. These two regions belong to different geomorphological units. The former includes a loess plateau and loess terraces, the latter alluvial plains and a loess terrace. These two regions also differ in the soil types that can be found in them. Same as with other heavy metals, the content and distribution of Ni and Cr in soil depend to a large measure on the parent material from which these soils had developed. High contents of these two metals in soil, as well as of the other heavy metals, may be constraints to the quality of the agro ecosystem. The aims of this study were to determine the contents of Ni and Cr in the soils of the two regions in northern Vojvodina and to identify their origins. A grid superimposed on a soil map of Vojvodina (R = 1:50.000) by means of a GIS tool GIS ArcView 10 has divided the agricultural land of the Province into 4 x 4 km units, each representing an area of 1,600 ha. Of the total number of 435 bulked soil samples taken, 228 and 207 respective samples represented the regions of northern Backa and northern Banat. The samples were analyzed for pseudototal contents of Ni and Cr. The contents were determined by ICP-OES after microwave assisted digestion with HNO3 and H2O2. Of the total of 435 samples analyzed, Ni content above the MAC (> 50 mg/kg) was recorded in 18 samples (2 from northern Backa, 16 from northern Banat). Cr content above the MAC (> 100 mg/kg) was found in only one sample, which came from northern Backa. In the soils of northern Backa, Ni content ranged from 4.3 to 58.1 mg/kg and the average value was 26.5 +/- 7.0 mg/kg, Cr content ranged from 6.2 to 128.7 mg/kg, 34.5 +/- 11.2 mg/kg on average. In the soils of northern Banat, Ni content was significantly higher (p < 0.05), ranging from 4.6 to 96.4 mg/kg and with the average value of 36.2 +/- 11.7 mg/kg. Cr content was also significantly elevated, the interval ranging from 5.8 to 78.3 mg/kg and the average value being 46.5 +/- 14.8 mg/kg. High correlations between these two metals (p < 0.01) were found for the soils of northern Backa and northern Banat, 0.83 and 0.92, respectively. The high correlation between their contents was an indication of the common geochemical origin of these two metals. Our results showed that the contents of Ni and Cr were higher in northern Banat than in northern Backa, indicating the geochemical origin of the two metals in the former region, which had soils with increased clay content. The obtained results also indicated that the measured levels of Ni and Cr in the soil are not limiting factors for production of safe food in northern Vojvodina.