Vörös A. szerk.: Fragmenta Mineralogica Et Palaentologica 13. 1987. (Budapest, 1987)

FRAGMENTA MINERALOGICA et PALAEONTOLOGICA 13. Budapest, 1987 21-51 Geochemistry of soil and subsoil interaction at Mezőnagymihály, NE Hungary By Gy. SZAKMÁNY (Received December 17, 1985) Abstract. Trace element geochemistry of six soil profiles down to subsoil has been investigated at Mezőnagymihály. Differential thermal analysis was applied to determine organic content, carbonates and clay minerals, and pH was measured. Optical emission spectrometry provided half-quantitative data of 13 trace elements. Soluble quantity of 5 trace elements (Mn, Zn, Cu, Pb, Cd) was determined by atomic absorption spectrometry. Ratios of trace elements in A-, B- and Clevels were compared, a trace element ecological picture of the area was formed and correlations were calculated for soluble trace elements and other parameters (pH, carbonate content, clay mineral content). Highest correlation is shown by soluble Zn and Pb. High correlation was calculated for Mn-Pb, Zn-Cu, and Cu-Pb pairs, too. High correlation was found for soluble quantities of Zn and Cu and the pH, while there is a low correlation for Pb and pH and no correlation coula be proved for Mn and pH. Soluble Zn, Cu and Pb display high correlation with the quantity of organic matter, while Mn does not. No high correlation could be proved for soluble element concentrations and clay mineral content; also, low correlation was shown for trace elements and carbonate content. INTRODUCTION Agrogeology is one of the most dynamically developing branch of geology in these days, laying considerable emphasis on investigations of soil and subsoil interaction. This relationship is examined here based on trace element content. Trace element content of the subsoil is a the decisive factor of trace element distribution in the upper soil levels. (Which is the level, from where cultivated plants absorp their nutrients. ) These micro-nutrients are trace elements; plants need minute quantities of them, but in their absence different deprivation diseases may occur. At the same time, if these trace elements are present in soluble quantities larger than necessary, they may be poisonous for the plants, for herbivorous animals and for man as well. As these two values are very close to each other in the case of some microelements, determination of their quantity is of utmost importance. If this quantity is unfavourable, it can be modified (e.g. by fertilizers). Our work was carried out in the surroundings of Mezőnagymihály. Soil profiles were examined down to the subsoil, to depths of 1. 5-2 m, taking samples at every 20 cm interval. Several investigations were made on the samples, specializing in the determination of more important soluble trace elements in the soil and subsoil. Such investigations have been very rare in Hungary up to now. In other countries, emphasis is laid on investigations of trace elements and their correlations occurring in the soils and subsequently in plants as a result of environmental pollution. REDOY and PATRICK (1977) recognized that pH is one of the most important factors influencing the solubility of heavy metals concentrated in the soil, and consequently of the pos-