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Constructed wetlands for steel slag leachate management: Partitioning of arsenic, chromium, and vanadium in waters, sediments, and plants

Gomes, Helena I.; Mayes, William M.; Whitby, Paul; Rogerson, Mike

Authors

Helena I. Gomes

William M. Mayes

Paul Whitby

Mike Rogerson

Abstract

Constructed wetlands can treat highly alkaline leachate resulting from the weathering of steel slag before reuse (e.g. as aggregate) or during disposal in repositories and legacy sites. This study aimed to assess how metal(loid)s soluble at high pH, such as arsenic (As), chromium (Cr), and vanadium (V) are removed in constructed wetlands and how they accumulate in the sediments and the plants (Phragmites australis, common reed). The results show that reedbeds were very effective at removing calciumCa (98%), Al aluminium (81%), Ba barium (98%), Cr chromium (90%), Ga gallium (80%), Ni nickel (98%), and Zn zinc (98%), and lowering pH and alkalinity. No statistical difference was found for As and V between leachate influent and wetland samples, showing that these metal(loid)s were not efficiently removed. As, Cr, and V were significantly higher in the reedbed sediments than in a reference site. However, sediment concentrations are not at levels that would pose a concern regarding reuse for agricultural purposes (average values of 39 ± 26 mg kg-1 for As, 108 ± 15 mg kg-1 for Cr, and 231 ± 34 mg kg-1 for V). Also, there is no significant uptake of metals by the aboveground portions of the reeds compared to reference conditions. Results show statistically significant enrichment in metal(loid)s in rhizomes and also a seasonal effect on the Cr concentrations. The data suggest minimal risk of oxyanion-forming element uptake and cycling in wetlands receiving alkaline steel slag.

Journal Article Type Article
Publication Date Aug 1, 2019
Journal Journal of Environmental Management
Print ISSN 0301-4797
Electronic ISSN 1095-8630)
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 243
Pages 30-38
DOI https://doi.org/10.1016/j.jenvman.2019.04.127
Keywords Alkaline drainage; Reedbeds; Passive treatment; Sediments; Phragmites australis
Publisher URL https://www.sciencedirect.com/science/article/pii/S0301479719305948?via%3Dihub
Additional Information This article is maintained by: Elsevier; Article Title: Constructed wetlands for steel slag leachate management: Partitioning of arsenic, chromium, and vanadium in waters, sediments, and plants; Journal Title: Journal of Environmental Management; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.jenvman.2019.04.127; Content Type: article; Copyright: © 2019 The Authors. Published by Elsevier Ltd.

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