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A brunisolic soil collected from an erosive forest land (HF-1-1) and a yellow soil from an accumulative shallow basin (HF-6-1) in the watershed of Lake Hongfeng (HF) were used for activity measurements of 7Be, 137Cs, 226Ra and 228Ra in different geochemical speciation. More than 85% of 7Be, 137Cs, 226Ra and 228Ra in the soils were bound to organic, Fe-Mn oxy-hydroxide and residual fractions. They could move with soil particles and be used as tracers for the erosion and/or accumulation of soil particles. 7Be geochemical speciation in the soils agreed with its trace for seasonal particle transport. 137Cs geochemical speciation was suitable for tracing soil particle accumulation and for sediment dating. 226Ra and 228Ra were combined in crystalline skeleton of clay minerals and mainly remained as residues in the soils and little was bound to the soluble, exchangeable and carbonate fractions. The differentiation of 226Ra/228Ra activity ratios in different geochemical fractions in the soils could be used as a parameter to trace accumulation and /or erosion of soil particles.
A brunisolic soil collected from an erosive forest land (HF-1-1) and a yellow soil from an accumulative shallow basin (HF-6-1) in the watershed of Lake Hongfeng (HF) were used for activity measurements of 7Be, 137Cs , 226Ra and 228Ra in different geochemical speciation. More than 85% of 7Be, 137Cs, 226Ra and 228Ra in the soils were bound to organic, Fe-Mn oxy-hydroxide and residual fractions. They could move with soil particles and be used as tracers for the erosion and / or accumulation of soil particles. 7Be geochemical speciation in the soils agreed with its trace for seasonal particle transport. 137Cs geochemical speciation was suitable for tracing soil particle accumulation and for sediment dating. 226Ra and 228Ra were combined in crystalline skeleton of clay minerals and mainly remained as residues in the soils and little was bound to the soluble, exchangeable and carbonate fractions. The differentiation of 226Ra / 228Ra activity ratios in different geochemical fractions in the soils could be used as a parameter to trace accumulation and / or erosion of soil particles.