Abstract
The objective of this study was to clarify the effect of temperature change on dissolution characteristics and chemical forms of boron and arsenic in four sediments (obtained from 50 m length boring core) from the middle part of the Arakawa Lowland located north of the Tokyo metropolitan area, Japan. Dissolution experiment (fractionated as water-soluble (dissolved) fraction) of these four sediments was carried out under anaerobic and different temperature (15°C, 25°C, and 40°C) conditions. For the sediments after the dissolution experiment, sequential extraction method that selectively fractionates five chemical forms (exchangeable fraction, bound to carbonates, bound to iron and manganese oxides, bound to organic matter, and residual fraction) was applied. Especially for some sediments which were significantly affected by temperature change in the dissolution experiment, maximum dissolution amount, i.e., total amount of water-soluble and exchangeable fractions and bound to carbonates increased with increase in temperature. On the other hand, bound to iron and manganese oxides showed a decreasing trend with increasing temperature. These results suggested that bound to iron and manganese oxides containing boron and arsenic changed to relatively soluble fractions of boron and arsenic such as water-soluble and exchangeable fractions and bound to carbonates with temperature increase.
