Saturday, 15 July 2006

Estimation of Lead and Cadmium Mobility in the Winter Wheat System.

Rimma Turekeldieva Jr., Taraz State Univ named by H. Dulati, Taraz, Kazakhstan

The estimation of change of the orientation of lead and cadmium biogenic migration in the investigated conditions was the aim of researches. We worked in the loamy meadow-sierozem soil on which the winter wheat of breed Karligash in the irrigation conditions in the south of Kazakhstan was cultivated. In the beginning of research we carried out the comparative studying of quantitative characteristics of sorbtion and durabilities of cadmium and lead fixings by humus acid of meadow sierozem soil and soils connected with number of mountain and premountain-semidesertic zones (mountain chernozem, mountain light-chestnut, ordinary sierozem and meadow sierozem). The received results have shown, that in the investigated types of soils a constant of stability of humin acids with cadmium complexes and lead has a tendency to increase in the line: mountain chernozem, mountain light-chestnut, meadow sierozem, ordinary sierozem, gray-brown soil. In the same line the reduction of exchange forms of heavy metals is marked. At the use of different norms of mineral fertilizers within three years in the meadow sierozem soil under winter wheat the authentic change of stable connection with humin acids and exchange forms of heavy metals has not been marked. The results of our researches have shown the appreciable variation of lead mobility in the meadow sierozem soil during the vegetative period. On the fertilized variants the contents of mobile lead in the top layer of soil by the end of vegetation was increased. However the distinctions between the variants were not always essential. In the arable layer of soil, on the variant with application of mineral fertilizers the contents of mobile lead was a little bit more than on the control variant. On the average for three years, the tendency to reduction of the lead contents in the arable layer of soil on the fertilized variants is observed. The application of high norms of fertilizers under winter wheat promoted increase of lead mobility in the arable layer, and also created the conditions for its migration in the lower horizons of meadow sierozem soil. The contents of mobile cadmium in meadow sierozem soil turned out one order lower than lead. Comparing the quantity of cadmium in the soil on the average for three years on the control and against a background of fertilizers application, the decrease of cadmium contents in the arable layer of the fertilized variants can be marked. At the end of winter wheat vegetation the stable reduction of cadmium at all variants in comparison with the initial contents is observed. However, the comparison of mobile cadmium contents in the soil on the variant without fertilizers and on the fertilized background shows, that accumulation of cadmium in the soil at application of fertilizers is distinctly more than on the control. The relative increase of cadmium mobility is observed in the sub-arable layer of the soil as well.

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