Mobilization of cesium in organic rich soils: correlation with production of dissolved organic carbon

• Published in: Water, air, and soil pollution air, and soil pollution, 1996-03, Vol.88 (1/2), p.133-144
• Main Authors: Tegen, I, Dorr, H
• Format: Article
• Language: English
• Subjects: Applied sciences; biological activity in soil; Biological and physicochemical properties of pollutants. Interaction in the soil; Carbon; Cesium; correlation; Decomposition; degradation; downward movement; Exact sciences and technology; fallout; forest soils; organic compounds; Pollution; radionuclides; seasonal variation; Seepage; seepage water; Soil and sediments pollution; soil depth; soil microorganisms; soil organic matter; soil pollution; soil temperature; soil water; soluble organic compounds; sorption; Trace analysis
• ISSN: 0049-6979; 1573-2932
• DOI: 10.1007/bf00157418

A study of the downward movement of super(1) super(3) super(7) Cs in an undisturbed forest soil is presented. Seasonal variations and depth profiles of super(1) super(3) super(7) Cs activities were measured in seepage water, which is the transport medium for the downward movement of anthropogenic substances in soils. Furthermore the correlation of super(1) super(3) super(7) Cs mobilization and production of dissolved organic carbon (DOC) was investigated. Seasonal variations of both super(1) super(3) super(7) Cs and DOC fluxes in the seepage water in a depth of 5 cm depth were observed, where the maximum fluxes in the summer months were about one order of magnitude higher than the minimum fluxes in the winter months. super(1) super(3) super(7) Cs fluxes are found to be correlated with DOC fluxes with a correlation coefficient of r=0.63, and both are highly correlated with soil temperature. This indicates that cesium is bound to soil organic material. The production of DOC is controlled by microbial decomposition of soil organic matter and we assume that this holds true for the super(1) super(3) super(7) Cs release as well. The actual transport velocity (0.2 plus or minus 0.14 mm/a) of super(1) super(3) super(7) Cs (calculated by the weighed mean of super(1) super(3) super(7) Cs concentration in the seepage water and the total super(1) super(3) super(7) Cs content of the soil) is about one order of magnitude less than the mean transport velocity (1.2 plus or minus 0.3 mm/a) over the past 25 years (calculated from the super(1) super(3) super(7) Cs depth profile). It is possible that the transport velocity of super(1) super(3) super(7) Cs in undisturbed soils decreases with time as it binds to aged organic material which is less easily decomposable than fresh organic material.