137Cs and 210Pb techniques are used to date a sediment core (MG4-2) retrieved from Maigang Reservoir in Ziyun County

Southwest Guizhou and infer its sedimentation rates. Three distinctive 137Cs peaks are identified in this core

which are ascribed to the abundant fallouts occurring in 1964

1975

and1986. The 210Pb ages calculated with CRS model are generally coincident to the ages inferred with 137Cs activities. However

there are also some discrepancies in the dates derived from the two methods. In particular

the age calculated with 210Pb for the depth with an age of 1964 inferred with 137Cs activities is remarkably different from the 137Cs age. Although the sedimentation rates derived with the two methods are different

both of them indicate a quite similar trend of changes in accumulation in the reservoir during the last decades. Sedimentation was rather slow in the earlier stage

then was fast in the middle stage

and finally slowed down again in the later stage. Such variations in sedimentation rate in MG4-2 may be due to the human being activities in the catchment of Maigang Reservoir. Simultaneous uses of 137Cs and 210Pb methods may allow cross-checks of the results derived with the two methods and thus lead more reliable and accurate chronology and sedimentation rate.