The applications of radiocesium-137 to soil redistribution and related studies in NE China: a review

Since the 1960s, fallout radiocesium-137 (¹³⁷Cs) has been widely used to study soil erosion and related issues. However, in this context, its specific applications have so far eluded a systematic analysis. To start filling this knowledge gap, the ¹³⁷Cs-derived achievements in Northeastern (NE) China were reviewed and its future needs and some implications were also given. Among the collated 81 papers, over 60 % were about soil erosion and its induced soil organic carbon (SOC) and nutrients loss. Over 25 % of the papers were about sedimentation dating, and only several studies employed ¹³⁷Cs as one type of fingerprints. Due to the decay of ¹³⁷Cs and short half-life, its mean inventory in soils will be difficult to be detected after around 50 years. Fortunately, it could be replaced by radionuclides ^239+240Pu and Np to estimate soil erosion due to their longer half-lives and similar transport behavior in soils to ¹³⁷Cs. Future studies can be conducted through mining sedimentation information in ponds, reservoirs, lakes, or in lowland areas by ¹³⁷Cs and other tracers. Furthermore, deep and more studies can be done when the ¹³⁷Cs technique is coupled with soil erosion models under land use and climate changes. The importance of expanding research at lager spatial scales is emphasized through their combinations under changing environments. This paper is intended to better conduct soil erosion and related issues through reviewing the applications of ¹³⁷Cs in NE China.