ỨNG DỤNG ĐỒNG VỊ PHÓNG XA TRONG NGHIÊN CỨU XÓI MÒN ĐẤT

Three fallout radionuclides isotopes (FRNI) 137Cs, 210Pb, and 7Be are being applied broadly to assess soil erosion in European continent. Among them, 137Cs shows the assessment of soil erosion in period of 50 years; 210Pb indicates in the period of 100 years, but 7Be can show a valuation of soil loss and re-accumulation of each rainy event. In Vietnam this FRNI techniques are being tested with comparison of conventional method (sediment measurement in the soil traps). And the results show that: Estimate soil erosion using FRNI 137Cs technique is ecceptable comparing with assessement by conventional method. It showed that soil erodibility in the Dong Cao watershed (50 ha) on the Acrisol derived from schist rock is moderate (vary about 4-5 tons/ha/yr). Using fallout 7Be measurement in short duration (each rainy events in 2007yr.) to estimate soil erosion and sedimentation broadly varies compared conventional practies. It happened because of fallout Be-7 is short duration activation isotope (T1/2=53 days), therefor it must be retested in the future. Using FRNI for soil erodibility evaluation, not only estimate soil erosion quantity as using conventional method, but also quality of eroded soil, through soil/sediment redistribution. Soil erodibility assessment using FRNI technique shows a general feature of surfaced soil movenment (erosion and accumulation) on the cultivated area.