Influence Of The Large Flood On The Element Composition Of Fluvisols In The Amur River Valley

Abstract

Floodplain soils function as long-lasting stock or source of different substances, including pollutants. The main factor determining biochemical processes in fluvisols is flooding. Global climate change, which is causing more frequent and massive floods, is urging us to assess the potential environmental risks and create appropriate environmental management strategies. This study was performed to estimate the impact of a heavy flood on the total content of major elements and both total and mobile trace elements in fluvisols of one of the longest rivers in the world, the Amur. The study was conducted in field conditions by sampling from the same soil profiles before and after the flood. As a result, 10 major and 42 trace elements were distinguished. Major-element composition was determined with X-ray fluorescent method, trace-element composition - with the inductive coupled plasma mass spectroscopy. Maximum decrease of concentration was determined for CaO, MnO, P2O5 (up to 60%) and Sr, Cd, Ba, Tl and Pb (up to 40%). Significant increase was in concentration of Ni, Cu, and Mo (up to 160%). Among mobile trace elements, increase was observed in concentration of Sc, Ni and Th (up to 400%). With the correlation analysis, it was also established that the main causes of changes in elemental composition of the soils were decrease of pH, development of redox environment and washing out of organic matter. The main factor determining the influence of the flood on fluvisols was floodplain relief, which affected the length of the inundation, flood water velocity and the way allochthonic matter retained.