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Accumulation, Release, and Solubility of Arsenic, Molybdenum, and Vanadium in Wetland Sediments

Journal of Environmental Quality

By:
and

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Abstract

This study was undertaken to determine the fate of As, Mo, and V (trace elements, TEs) in the sediments of a constructed wetland in use for the remediation of potentially toxic trace element-contaminated agricultural drainwater. After three years of wetland operation, sediment cores were collected to determine changes in TE concentrations as a function of depth and the effects of varying water column depth. All TE concentrations were highest in the top 2 to 4 cm and decreased with depth. Molybdenum accumulated in the wetland sediments, up to levels of 32.5 ?? 4.6, 30.2 ?? 8.9, and 59.3 ?? 26.1 mg kg-1 in the top 1 cm of sediment at water depths of 15, 30, and 60 cm, respectively. In the top 2 cm of sediment, As accumulated (28.2 ?? 3.0 mg kg-1) only at the 60-cm water depth. Below 2 cm, as much as 10 mg kg-1 of As was lost from the sediment at all water depths. In most cases, V concentrations decreased in the sediment. In this wetland system, the lowest redox potentials were found near the sediment surface and increased with depth. Thus, in general As, Mo, and V concentrations in the sediment were highest under more reducing conditions and lowest under more oxidizing conditions. Most of the accumulated Mo (73%) became water soluble on drying of samples. This has important implications for systems undergoing changes in redox status; for instance, if these wetland sediments are dried, potentially large amounts of Mo may be solubilized.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Accumulation, Release, and Solubility of Arsenic, Molybdenum, and Vanadium in Wetland Sediments
Series title:
Journal of Environmental Quality
Volume
32
Issue:
6
Year Published:
2003
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Environmental Quality
First page:
2428
Last page:
2435
Number of Pages:
8