Metal-sulfide dynamics in a constructed wetland in the Southeastern United States
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ORIGINAL PAPER
Metal-sulfide dynamics in a constructed wetland in the Southeastern United States Savannah Harris . Xiaoyu Xu
. Gary Mills
Received: 18 November 2019 / Accepted: 4 September 2020 Ó Springer Nature B.V. 2020
Abstract The Tritium Processing Facility at the Savannah River Site releases effluent containing copper (Cu), zinc (Zn), and lead (Pb) to the H-02 constructed wetland for remediation before the final release. Sediment cores were collected in the wetland cells in both summer and winter. Concentrations of total metals in all sediment layers and acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) in surface sediments were determined. Total metal concentrations suggested most metals removed from surface water were retained by the organic-rich flocculent in the top sediment layers instead of being Disclaimer: This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11273-020-09749-6) contains supplementary material, which is available to authorized users.
transported to the deeper sulfide mineral layers. The seasonal difference of AVS and SEM indicated a season-related sulfur cycle and metal removal process in the wetland cells. SEM-Zn was the major contributor to total SEM. Metals accumulating in surface sediments were mainly sequestered in AVS and SEM extractable phases including metal-sulfides and organic matter complexes. The general SEM/AVS ratio was [ 1, demonstrating the metals associated with sediments were potentially mobile and/or bioavailable, which becomes a concern for the longterm sustainability of the constructed wetland. The disturbance event in the sediment triggered the release of total metals, which were mostly in particulate form and were not bioavailable. Due to the high levels of reduced ion (Fe) in the sediment, the released particulate metals were likely to form metal-scavenging particulate Fe3? oxyhydroxides under oxic conditions. Keywords Acid-volatile sulfide Constructed wetland Diffusive gradients in thin films Metal Resuspension Simultaneously extracted metals
S. Harris X. Xu (&) G. Mills Savann
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