Removal, distribution and retention of metals in a constructed wetland over 20 years

Knox, Anna Sophia; Paller, Michael H.; Seaman, John C.; Mayer, John J.; Nicholson, Cher

doi:10.1016/j.scitotenv.2021.149062

Cited by 19 publications

(9 citation statements)

References 36 publications

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“…This suggests that urban streams and stormwater BMPs (bioswales, bioretention sites, wetlands and ponds) behave more similarly to one another with respect to base cation source and sink dynamics than has been suggested in previous literature (Semadeni-Davies 2006;Gill et al, 2017;Barbier et al, 2018;Burgis et al, 2020;Knox et al, 2021;Maas et al, 2021). Stormwater ponds had previously been found to retain metals (Gill et al, 2017;Knox et al, 2021) but at a decreased efficiency (~50% summer performance) in the winter after roadsalt input (Semadeni-Davies 2006). Stormwater ponds were also found to mobilize base cations after road salting events (Barbier et al, 2018).…”

Section: Discussionmentioning

confidence: 68%

“…2021), which found chemical cocktail mobilization of Ca 2+ , K + , Na + , Mg 2+ , Cu, Mn and Sr 2+ during road salting events in urban streams using routine sampling and high-frequency sensors. This suggests that urban streams and stormwater BMPs (bioswales, bioretention sites, wetlands and ponds) behave more similarly to one another with respect to base cation source and sink dynamics than has been suggested in previous literature (Semadeni-Davies 2006;Gill et al, 2017;Barbier et al, 2018;Burgis et al, 2020;Knox et al, 2021;Maas et al, 2021). Stormwater ponds had previously been found to retain metals (Gill et al, 2017;Knox et al, 2021) but at a decreased efficiency (~50% summer performance) in the winter after roadsalt input (Semadeni-Davies 2006).…”

Section: Discussionmentioning

confidence: 70%

“…We believe that salt type, salt concentration, and stormwater BMP type are key factors which control the mobilization of chemical cocktails from stormwater BMP sediments into aqueous form (Semadeni-Davies 2006;Gill et al, 2017;Snodgrass et al, 2017;Barbier et al, 2018;Burgis et al, 2020;McGuire and Judd 2020;Knox et al, 2021;Maas et al, 2021;Kaushal et al, 2022b). We hypothesize that increasing salt concentration will increase mobilization of base cations and metals into solution.…”

Section: Introductionmentioning

confidence: 90%

“…While they are an effective sink of Na + , Mg 2+ and Ca 2+ , through cation exchange, stormwater BMPs are also a simultaneous source of other base cations and metals (Figure 3) (Kaushal et al, 2022b). Other studies indicate that there is significant retention of various base cations and metals in stormwater ponds (Semadeni-Davies 2006; Barbier et al, 2018), wetlands (Gill et al, 2017;Knox et al, 2021), accidental wetlands (Maas et al, 2021), bioswales and bioretention features (Burgis et al, 2020), but less work has directly analyzed the impacts of salt ions on ion exchange and release of contaminants (Kaushal et al, 2022). The potential for retention or release of contaminants can be influenced by site-specific characteristics, such as a hypersaline layer developing only in deeper sections of stormwater ponds (Semadeni-Davies 2006), or wetlands delaying peak discharge and therefore lessening peak salinity (Maas et al, 2021).…”

Section: Variations In Ion Retention and Release Among Stormwater Bmpsmentioning

confidence: 98%

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Stormwater best management practices: Experimental evaluation of chemical cocktails mobilized by freshwater salinization syndrome

Galella

Kaushal

Mayer

et al. 2023

Front. Environ. Sci.

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Freshwater Salinization Syndrome (FSS) refers to the suite of physical, biological, and chemical impacts of salt ions on the degradation of natural, engineered, and social systems. Impacts of FSS on mobilization of chemical cocktails has been documented in streams and groundwater, but little research has focused on the effects of FSS on stormwater best management practices (BMPs) such as: constructed wetlands, bioswales, ponds, and bioretention. However emerging research suggests that stormwater BMPs may be both sources and sinks of contaminants, shifting seasonally with road salt applications. We conducted lab experiments to investigate this premise; replicate water and soil samples were collected from four distinct stormwater feature types (bioretention, bioswale, constructed wetlands and retention ponds) and were used in salt incubation experiments conducted under six different salinities with three different salts (NaCl, CaCl2, and MgCl2). Increased salt concentrations had profound effects on major and trace element mobilization, with all three salts showing significant positive relationships across nearly all elements analyzed. Across all sites, mean salt retention was 34%, 28%, and 26% for Na+, Mg2+ and Ca2+ respectively, and there were significant differences among stormwater BMPs. Salt type showed preferential mobilization of certain elements. NaCl mobilized Cu, a potent toxicant to aquatic biota, at rates over an order of magnitude greater than both CaCl2 and MgCl2. Stormwater BMP type also had a significant effect on elemental mobilization, with ponds mobilizing significantly more Mn than other sites. However, salt concentration and salt type consistently had significant effects on mean concentrations of elements mobilized across all stormwater BMPs (p < 0.05), suggesting that processes such as ion exchange mobilize metals mobilize metals and salt ions regardless of BMP type. Our results suggest that decisions regarding the amounts and types of salts used as deicers can have significant effects on reducing contaminant mobilization to freshwater ecosystems.

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Section: Discussionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 90%

Section: Variations In Ion Retention and Release Among Stormwater Bmpsmentioning

confidence: 98%

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Stormwater best management practices: Experimental evaluation of chemical cocktails mobilized by freshwater salinization syndrome

Galella

Kaushal

Mayer

et al. 2023

Front. Environ. Sci.

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“…This observation is related to solids remobilization in constructed wetlands with longer residence times. [ 64 ]; noted that when solids remobilization occurs, it limits the effectiveness of wetland systems with longer residence times. Meanwhile, TSS was greatly reduced by media in constructed wetlands as the plant was decreasing another parameter, it occurs because constructed wetland media has a mixture of materials that potentially filtered TSS [ 94 ].…”

Section: Resultsmentioning

confidence: 99%