Reference value of 137Cs tracing technique in soil loss estimation: A spatial variation analysis
137Cs示踪法土壤侵蚀量估算的本底值问题

Soil erosion and its eco-environmental effects are important issues among environmental topics. Quantitative estimation or measurement of soil loss is one of the main fields in soil erosion researches. As a short-time consuming and relatively simple method, 137Cs tracing technique was widely applied in quantitative estimation of soil loss caused by natural driving forces or human activities. Measurement of reference value is fundamental in estimating soil loss rate by the 137Cs tracing method. Impacted by multi factors that intrinsically are of spatial heterogeneity, 137Cs background fallout varied across landscapes. It was enucleated here how weather, topography, soil properties and land use/cover impacted spatial distribution of 137Cs and strengthened its spatial variation. Meanwhile, existence of soil sample sites for 137Cs references deposition value measurement and veracity of sample site selection were discussed. Based on the above analysis, a framework subdividing target area into humongous measurement units and employing hierarchical multi-reference system and topographical rectification were suggested as solutions for handling spatial heterogeneity of 137Cs reference value. Further studies are needed to quantify the effect of each factor on spatial variation of 137Cs reference fallout and to eventually establish principles and methods for subdividing measurement unit.