GEOCHEMICAL PATTERNS IN SOILS OF THE KARST REGION, CROATIA

Soil samples were collected at 420 locations in a 5-km grid pattern in the Istria and Gorski Kotar areas of Croatia, and on the Croatian isl ands of Cres, Rab and Krk, in order to relate geochemical variation in the soils to underlying differences in geology, bedrock lithology, so il type, environment and natural versus anthropogenic influences. Spec ific objectives included assessment of possible agricultural and indus trial sources of contamination, especially from airborne effluent emit ted by a local power plant. The study also tested the adequacy of a fi xed-depth soil sampling procedure developed for meager karstic soils. Although 40 geochemical variables were analyzed, only 15 elements and 5 radionuclides are common to all the sample locations. These elements can be divided into three groups: (1) those of mostly anthropogenic o rigin - Pb, V, Cu and Cr; (2) those of mixed origin - radionuclides an d Zn; and (3) those of mostly geogene origin - Ba, Sr, Ti, Al, Na, Ca, Mg, Fe, Mn, Ni and Co. Variation in Pb shows a strong correlation wit h the pattern of road traffic in Istria. The distributions of Ca, Na a nd Mg in the flysch basins of southern Istria and Slovenia are clearly distinguishable from the distributions of these elements in the surro unding carbonate terrains, a consequence of differences in bedrock per meability, type of drainage and pH. The spatial pattern of Cs-137 from the Chernobyl nuclear power plant accident reflects almost exclusivel y the precipitation in Istria during the days immediately after the ex plosion. (C) 1997 Elsevier Science B.V.