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Environmental study on the river sediments using chemical speciation of iron by Mossbauer spectroscopy.

通过穆斯堡尔光谱法利用铁的化学形态对河流沉积物进行环境研究。

基本信息

批准号：
10640583
负责人：
MATSUO Motoyuki
金额：
$ 2.11万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640583/
关键词：
Mossbauer spectroscopy chemical speciation of iron river sediment estuarine area pyrite vertical distribution sulfate-reducing bacteria 多摩川河口域

项目摘要

Urban estuarine sediments are rich in organic materials and provide an anaerobic environment where hydrogen sulfide, one of the substances responsible for malodor, is intensively produced through microbial and/or chemical reduction of sulfate ions from seawater and finally removed from water to the sediment in the form of iron sulfides. In this study, the chemical states of iron, and its vertical distribution, have been investigated by ^<57>Fe Mossbauer spectroscopy for the sediments collected from several urban rivers. Mossbauer spectra of the estuarine sediments consist of three doublets and one sextet, which are ascribable to paramagnetic high-spin Fe^<2+>, paramagnetic high-spin Fe^<3+>, pyrite (FeS_2) and magnetic high-spin Fe^<3+>, respectively. The relative amount of pyrite shows a maximum at the depth of 20-40 cm from the surface, whereas that of paramagnetmc Fe^<2+> changes complementarily to pyrite. This suggests that this component in the estuarine sediments converted to pyrite under reducing conditions. No significant seasonal variation was found in this trend. The stratified distribution of pyrite was also found in the sediment collected from Kitajukken-river and Tate-river, which are canal-rivers in Tokyo. On the other hand, pyrite was not always found in the Sagami-river sediments, but the same trend of pyrite distribution was found in the sediment collected near a sewage treatment plant. In order to clarify the contribution of sulfate-reducing bacteria to pyrite formation in the sediments, we determined the vertical distribution for number of living sulfate-reducing bacteria in the sediments by plating method. This distribution was found to be consistent with that of pyrite.

城市河口沉积物富含有机物质，提供了厌氧环境，其中硫化氢（造成恶臭的物质之一）通过微生物和/或化学还原海水中的硫酸根离子而大量产生，并最终以硫化铁的形式从水中去除到沉积物中。在本研究中，通过^<57>Fe穆斯堡尔光谱法对从几条城市河流收集的沉积物中铁的化学状态及其垂直分布进行了研究。河口沉积物的穆斯堡尔谱由3个二重峰和1个六重峰组成，分别归因于顺磁性高自旋Fe^<2+>、顺磁性高自旋Fe^<3+>、黄铁矿(FeS_2)和磁性高自旋Fe^<3+>。黄铁矿的相对量在距离表面20-40cm的深度处显示最大，而顺磁性Fe 2+ 的相对量与黄铁矿互补地变化。这表明河口沉积物中的该成分在还原条件下转化为黄铁矿。这一趋势没有发现显着的季节性变化。在东京运河河流北十间川和立川收集的沉积物中也发现了黄铁矿的分层分布。另一方面，相模川沉积物中并不总是发现黄铁矿，但在污水处理厂附近收集的沉积物中也发现了同样的黄铁矿分布趋势。为了明确沉积物中硫酸盐还原菌对黄铁矿形成的贡献，我们采用平板法测定了沉积物中活硫酸盐还原菌数量的垂直分布。发现这种分布与黄铁矿的分布一致。