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To establish a 239+240 Pu, 137 Cs, and heavy metal reference soil site in Northeast China, three grassland soil cores were collected from the Lao-Ye-Ling Mountain, which is a branch of the Chang-Bai Mountains. The activities were in the range of 0.041−2.752 mBq/g for 239+240 Pu and in the range of 0.2−57.6 mBq/g for 137 Cs. The 240 Pu/ 239 Pu atomic ratios were 0.161−0.186, showing that 239+240 Pu in the study area originated from the global fallout. Also, 239+240 Pu, 137 Cs, and excess 210 Pb were enriched in the surface soil. The convective−dispersion equation model provided the lower apparent dispersion coefficients (D) and apparent convection velocities (v) for both 239+240 Pu and 137 Cs. The soil erosion rate in this study area was estimated by an erosion model, which was lower than that in the other area of Northeast China. 239+240 Pu in the different soil fractions was analyzed by a sequential extraction method, and the result showed that 239+240 Pu was mainly adsorbed by Fe/Mn oxides and their associated organic matter (NOM Fe/Mn-oxides fraction). Except for Fe, all other heavy metals from the anthropogenic source were enriched in the surface soil. The pollution level of heavy metals in this study area was lower. In general, the alpine grassland soil of the Lao-Ye-Ling Mountain can be used as a reference soil site to study environmental pollution and soil erosion and provided some reference baselines for future multidisciplinary studies in Northeast Asia.

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