The effect of the 2013 flood on the rare earth elements content in alluvial soils of the Amur River floodplain

Disastrous flood effect on the content of the total and mobile form of rare earth elements has been studied in the alluvial soil in the middle reach of Amur River. Relationships between rare earth and major element concentrations and soil properties before and after the flood have been revealed. Elements concentration was measured by using ICP–MS. Correlation test used for revealing the interactions between soil properties and REE concentrations. Contents of REE in soils increasing with the distance from the riverbed and heaving of granulometric soil composition. Total contents of REE prior the flood varied from 70 to 170 mg/kg–1 while mobile forms of REE varied from 1 to 11 mg/kg–1. Flood results in REE accumulation in the alluvial soils, accumulation mainly occurred on the surfaces of clay minerals and mobility of REE is affected by soil pH. Flood increase adsorption of REE by organic matter and phosphates. In average total REE contents increased by 10 %, mobile forms — by 70 %. Correlation coefficients with organic matter and phosphorus oxides after flooding are improved.Работа выполнена при поддержке гранта РФФИ (грант № 18-05-00151 А)