The origin of soil selenium (Se) is relatively complex, and analysis of the origin of soil Se is of great significance in clarifying the cause of its richness and the impact of human activities on soil environmental quality, as well as assisting in the scientific planning of Se-rich land use, improving land use value, and promoting regional economic development. In this study, in order to identify and clarify the origin of soil Se and the causes of its richness in a typical agricultural area in the Hamatong River Basin of the Sanjiang Plain, we tested the Se concentrations in soil, atmospheric deposition, irrigation water, chemical fertilizer, rock, and rice crop samples from the study area. Geostatistical analysis indicated that the soil Se is mainly controlled by natural factors such as soil parent material. Elemental geochemical analysis indicated the soil Se is mainly derived from the granite occurring in the Wanda Mountains. Elemental mass balance analysis indicated that the atmospheric deposition is the most important source of soil Se input, with a contribution of 84.90%, followed by irrigation and fertilization. Deep percolation is the main pathway of soil Se output, with a contribution of 74.17%, followed by rice crop harvest and volatilization. In addition, the soil Se is derived from a natural source, its richness can be attributed to the effect of anthropogenic factors, such as fossil fuel combustion and fertilization, superimposed on the high natural background value of soil Se.

The origin of soil selenium (Se) is relatively complex, and analysis of the origin of soil Se is of great significance in clarifying the cause of its richness and the impact of human activities on soil environmental quality, as well as assisting in the scientific planning of Se-rich land use, improving land use value, and promoting regional economic development. In this study, in order to identify and clarify the origin of soil Se and the causes of its richness in a typical agricultural area in the Hamatong River Basin of the Sanjiang Plain, we tested the Se concentrations in soil, atmospheric deposition, irrigation water, chemical fertilizer, rock, and rice crop samples from the study area. Geostatistical analysis indicated that the soil Se is mainly controlled by natural factors such as soil parent material. Elemental geochemical analysis indicated the soil Se is mainly derived from the granite occurring in the Wanda Mountains. Elemental mass balance analysis indicated that the atmospheric deposition is the most important source of soil Se input, with a contribution of 84.90%, followed by irrigation and fertilization. Deep percolation is the main pathway of soil Se output, with a contribution of 74.17%, followed by rice crop harvest and volatilization. In addition, the soil Se is derived from a natural source, its richness can be attributed to the effect of anthropogenic factors, such as fossil fuel combustion and fertilization, superimposed on the high natural background value of soil Se.