Soil erosion and pollutant loss of Danjiangkou city in south China based on 137Cs technique

Danjiangkou city is the main part of Danjiangkou reservoir area which is the catchments area for the South-to-North Water Transfer (middle line) project in China. Soil erosion and the subsequent pollutants loss are important influencing factors on its water quality. In this paper, soil erosion rate were analyzed based on 137Cs tracer technique, and the mathematic models were simulated among 137Cs contents and the organic matter, total phosphorus, heavy metals. The 137Cs reference inventory in the study area was 2153.46Bq m-2. Predicted soil erosion rates for different land use varied from 599.07 t km-2 year-1 to 6055.5 t km-2 year-1, the highest erosion rate was observed in dry land distributed on hilly areas, followed in sequence by cultivated slope land, kale yard land, paddy land and grassland. High correlation was apparent between 137Cs content and soil organic matters (R=0.721), soil Cu (R=0.751), soil Cr (R=0.886), soil Pb (R=0.799), soil Zn (R=0.756) and soil Ni (R=0.724), Low correlation was apparent between 137Cs contents and total phosphorus contents based on all the soil sample (R=0.297), but correlation coefficient are higher than 0.6 in the single land use area.