Facilitated Immobilization of Heavy Metals in Soil by Manipulation with Plant Byproducts
Abstract
Humic substances (HS) are frequently the key sorption sites for metal ions in soils, especially where bioavailability is concerned. Understanding the chemical status of HS and their interactions with metal ions is critically important for long-term sustainability of any in situ remediation measure. However, this remains a difficult challenge. Once understood in sufficient detail, the chemical mechanism(s) of metal immobilization by soil HS may be exploited to achieve desirable remediation goals in a wide range of contaminated soils. Thus, in this proof-of-concept pilot study, we had the following two objectives: Can soil humic substances be manipulated to help sequester heavy elements in soils? Can the chemical sequestration mechanism(s) be understood? To achieve these objectives, we investigated the chemistry of soil humification process in relation to heavy metal ion leaching by conducting soil ageing experiments with McClellan AFRPA soils. Different organic bulk materials including cellulose (Cel), lignosulfonate (LS), wheat straw (WS), pine shavings (PS) were added in combination with CaCO3 (CC), along with a no amendment control (blank). The turnover of individual humic substructures was followed in separate ageing experiments by chasing 13C and 15N labels from pre-labeled HS. A combination of NMR, pyrolysis gas chromatography-mass spectrometry (Pyro-GCMS), and 3-D fluorescence techniques was employed to characterize the humified products and their 13C and 15N displacement. For correlation of metal mobility with humic chemistry, a broad spectrum of elements in the soil leachates was measured using ICP-MS. These new studies follow on our recent report (2) that turnover and not the abundance of certain HS substructures is linked to reduced metal leaching.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2005
- Accession Number
- ADA635025
Entities
People
- Richard M. Higashi
- Teresa W. Fan
Organizations
- University of Louisville