Mobility of 137Cs, 10Be and 210Pb in soil as a function of the soil texture, organic matter content and pH

Vertical matter transfer processes (bioturbation and <2μm translocation) in soils and their dynamics are up to now poorly constrained although they are responsible for the temporal evolution of the ecosystem services. In order to better constrain and quantify these processes, a kinetic quantification of the involved transfers based on vertical profiles of 210Pb (xs), 10Be and 137Cs has been developed for Luvisols in which soluble transfers could be neglected. The range of applicability of this type of approach was nevertheless not tested. In this work, we analyzed 210Pb (xs), 10Be and 137Cs in soils exhibiting gradients of organic matter, pH and < 2 μm fraction (Podzol, Andosol Ferralsol, Leptosol). Acidic soils and large organic matter contents were considered. The depth distribution of the studied isotopes was then interpreted as a function of the organic matter content, the soil pH and its < 2 μm fraction. This demonstrates that 10Be and 137Cs losses occur under soluble form in the Podzol, especially under forest, more acid, for the latter. Soluble 10Be transfers were also identified in the Andosol when they were considered as negligible in the Leptosol. For 210Pb (xs), soluble transfers are also probable for soils with pH less than 5.5 (Andosol and Ferralsol) and strong affinity for organic matter has been demonstrated. Thus, under acidic conditions and low < 2 μm fraction, soluble transfer cannot neglected anymore.