Mercury content in agricultural soils (Vojvodina Province, Serbia)

The Vojvodina Province in northern Serbia is well known for its intensive field crops production. Over 90 % of total arable land, which represents more than 1500.000 ha, is used for field or vegetable crop production. A grid superimposed on Vojvodina land by means of a GIS tool (GIS ArcView 10) has divided land into 4 × 4 km units, each representing an area of 1600 ha. Total number of 1370 bulked soil samples were taken (0-30 cm depth) from agricultural land and analysed for total mercury content THg. The samples were analysed using Direct Mercury Analyzer DMA 80 Milestone. Quality control was carried out with IRMM BCR reference materials 143R. The aim of this study was to determine the total content of Hg in agricultural soils and its spatial distributions in different parts of Vojvodina Province. The obtained results were within interval 0.008-0.974 mg kg^-1. The average concentration of Hg was 0.068, with median 0.048 mg kg^-1. The correlation was determined between Hg concentration and organic matter content in the soil. Content of Hg coincides with main geomorphological units of Vojvodina Province. Average values of Hg concentrations for soils formatted on different geomorphological units were 0.031 for sandy area with dune fields, 0.048 for alluvial terraces, 0.055 for upper Pleistocene terraces, 0.058 for loess plateaus, 0.083 for mountains and 0.092 mg kg^-1 for alluvial plains. Hg spatial distribution confirmed that most of Vojvodina Province area has geochemical origin of Hg. Higher concentration of Hg on alluvial plains indicated that the origin of Hg near rivers could be from anthropogenic source. The main rivers in Vojvodina have been dammed more than a century ago. Thus, higher concentrations of Hg in their alluvial plains out of narrow dammed zone around the rivers must be related to natural and anthropogenic sources located in their huge catchments. Higher content of Hg in mountain region can be explained by high clay content in these soils. Additional hotspots of Hg concentration of top soils are related to geographical locations of major towns. The obtained results also indicated that the measured levels of Hg in the soil are not limiting factors for production of safe food in Vojvodina.