The performance of a free surface and metal-removing constructed wetland: How a young wetland becomes mature

Xu, Xiaoyu; Mills, Gary L.; Lindell, Angela H.; Peck, Erin; Korotasz, Alexis M.; Burgess, Elizabeth A.

doi:10.1016/j.ecoleng.2019.04.020

Cited by 22 publications

(18 citation statements)

References 24 publications

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“…The engineered diagram of the H‐02 constructed wetland system is indicated in Supplemental Data, Figure S1. Retention basin, wetland cell 1, wetland cell 2, and stream were selected as the experimental sites, considering their variable metal concentrations and water chemistries (Xu and Mills 2018; Xu et al 2019b). Yellow lampmussels ( Lampsilis cariosa ) and DGT were deployed together in the water of the 4 sampling sites for 12 d in the summer (21 May–2 June 2018) and 12 d in the winter (6–18 December 2018).…”

Section: Methodsmentioning

confidence: 99%

“…Yellow lampmussels ( Lampsilis cariosa ) and DGT were deployed together in the water of the 4 sampling sites for 12 d in the summer (21 May–2 June 2018) and 12 d in the winter (6–18 December 2018). The 2 seasons were selected because of their differences in precipitation, water chemistry, and metal speciation (Xu and Mills 2018; Xu et al 2019b; National Oceanic and Atmospheric Administration 2020). The cumulative rainfall was 11.3 cm for the summer trial and 6.9 cm for the winter trial (Table 1).…”

Section: Methodsmentioning

confidence: 99%

“…In the model input, water temperature and pH values were derived from the field measurements; concentrations of DOC, sulfate, chloride, and metals were derived from the laboratory chemical analysis. Colloidal fulvic acid (FA) and humic acid (HA) were assumed as the 2 major components of DOC in this model: fulvic acid accounted for 10% of DOC and humic acid accounted for 90% (Xu et al 2019b). Other biogenic components in the dissolved organic matter (DOM) were not considered.…”

Section: Methodsmentioning

confidence: 99%

“…The present study explored the validity of using DGT to assess metal speciation and bioavailability in the H‐02 constructed wetland in different seasons, where DGT deployment was coupled with metal accumulation in freshwater mussels. The H‐02 wetland was established to remove heavy metals from the process water and storm runoff water released by the Tritium Processing Facility on the Savannah River Site (Aiken, SC, USA; Mills et al 2011; Xu and Mills 2018; Xu et al 2019b). This wetland was selected as it has 2 major contaminants (Cu and zinc [Zn] mixture) in the water with clear concentration gradients in different sites of the wetland system.…”

Section: Introductionmentioning

confidence: 99%

“…This wetland was selected as it has 2 major contaminants (Cu and zinc [Zn] mixture) in the water with clear concentration gradients in different sites of the wetland system. Total metal concentrations that were below the acute toxicity level tended to decrease in the order of retention basin, influent, wetland cells, effluent pool, and stream (Supplemental Data, Figure S1; Xu and Mills 2018; Xu et al 2019b). Meanwhile, seasonal differences in water chemistry, sulfur cycle, and metal removal mechanisms, which relate to metal speciation and bioavailability, were indicated by this wetland (Xu and Mills 2018).…”

Section: Introductionmentioning

confidence: 99%

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Limitations of Applying Diffusive Gradients in Thin Films to Predict Bioavailability of Metal Mixtures in Aquatic Systems with Unstable Water Chemistries

Peck

Fletcher

et al. 2020

Enviro Toxic and Chemistry

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The present study accessed the use of diffusive gradients in thin film (DGT) as a surrogate for estimating the bioavailability and bioaccumulation of copper (Cu) and zinc (Zn) in a freshwater mussel. We coupled DGTs with mussels and deployed them in a constructed wetland. Water quality parameters were measured for a 4-d period on 3 continuous occasions during 12-d trials in the summer and winter; metal speciation was modeled for each occasion. Higher cumulative rainfall and water turbidity during the summer trial resulted in higher particulate metal concentrations compared to the winter trial. Mussel accumulated metals did not correlate with DGT-measured metals but positively correlated with particulate metals in the summer because filtering particulate food mainly contributed to the bioaccumulation. In contrast, the winter trial suggested a positive correlation between metal bioaccumulation and DGT-measured metals because uptake of dissolved organic matter (DOM) from water mainly contributed to the bioaccumulation, and the labile metal species complexed with DOM generally overlapped with DGT-targeted metals. Though Cu has a higher affinity for organic ligands than Zn, the interactions between Cu and Zn in the mixture did not impede their uptake and bioaccumulation. The deployment duration when DGTs and mussels are coupled to compare metal bioavailability should be no less than 12 d so that mussels have enough time to accumulate contaminants from the environmental media. In summary, DGT is a convenient surrogate for biomonitoring, but it may not fit the real environment such as the aquatic system with unstable water chemistries. Geochemical modeling is good at calculating metal speciation but inferior to DGT in predicting bioavailability and mimicking bioaccumulation.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%