The process of manganese deposition in paddy soils

Open Access
Publisher Website
Google Scholar
Abstract
From the close examination of the process of Mn-deposition in the paddy soils, a hypothesis concerning the Mn-deposition was proposed. In this hypothesis. the process is divided into two stages (the initial stage and the later stage). In the initial stage Mn2+ is rapidly oxidized by microorganisms, forming tiny Mn-deposits. In the later stage, Mn2+ is slowly oxidized non-biologically on the surface of the tiny Mn-deposits and increases the size of the tiny Mndeposits. To verify this hypothesis, models for the reduced plough layer which was exposed to the atmosphere by drainage were used. The number of Mn-deposits increased rapidly during the first 24 hr of incubation and remained almost unchanged afterwards. Toxic substances such as streptomycin, sodium azide, chloramphenicol, and antimycin suppressed the formation of the Mn-deposits during the first 24 hr of incubation. Microorganisms which were stained with MnO2 were frequently recognized in the Mn-deposits. These results are thought to support the presumed biological oxidation of Mn2+ in the initial stage. The biological oxidation of Mn2+ was also found to be affected by several factors such as soil pH and Mn2+ content. The rate of the non-biological oxidation of Mn2+ in the later stage was confirmed to be very slow.

This publication has 3 references indexed in Scilit: