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Nanotoxicology research commonly utilizes pristine nanomaterials for toxicity assessment, which may not be perfectly representative of what is released into environmental systems. The goal of the present study was to develop a method to simulate human weathering of silver-containing textiles. To achieve this goal the roles of physical and chemical stress on X-Static® containing athletic textiles were investigated and compared to data collected from human weathering experiments and literature. Chemical weathering methods (artificial sweat) were used independently and alongside physical weathering methods (3D printed stretching and abrasion instruments). Non-weathered control textiles were found to release 29 ± 11 mg Ag/kg of textile into wash water effluent (ICP-MS), with 16% being released as ionic silver (ICP-MS) and the rest as metallic nanomaterials, nanosheets, and particulates of varying size (SEM/XANES). Real and simulated human weathered textiles released similar amounts of total silver (67 ± 11 mg Ag/kg, 84 ± 13 mg Ag/kg respectively) with the silver released being composed of ionic (1.5%, 2%) and a mixture of metallic and chlorinated nanomaterials, nanosheets, and particulates. The method was shown to effectively detach environmentally representative silver materials from silver-containing textiles and can provide such materials for future studies on the assessment of their fate, transport, and toxicity.

The factors controlling per- and polyfluoroalkyl substances (PFAS) environmental fate remains the subject of considerable debate and study. As surfactants, PFAS readily partition to interfaces, a property that controls their transport and fate. A group contribution model is developed to predict the extent to which PFAS partitions to the air-water interface. Langmuir adsorption and Szyszkowski equation parameters were fitted to literature air-water surface tension data for a range of PFAS and conventional hydrocarbon surfactants. This approach enabled the prediction of the impact of the hydrophilic head group, and other molecular components, on PFAS interfacial partitioning in instances when PFAS data are unavailable but analogous hydrocarbon surfactant data are available. The model was extended to predict a range of parameters (i.e., solubility, critical micelle concentration (CMC), KD, Koc and Kow) that are used to predict PFAS environmental fate, including long-range PFAS transport and in multimedia models. Model predictions were consistent with laboratory and field derived parameters reported in the literature. Additionally, the proposed model can predict the impact of pH and speciation on the extent of PFAS interfacial partitioning, a potentially important feature for understanding the behaviors of some ionizable PFAS, such as fluorinated carboxylic acids. The proposed model provides a conceptually straightforward method to predict a wide range of environmental fate parameters for a wide range of PFAS. As such, the model is a powerful tool that can be used to determine parameters needed to predict PFAS environmental fate.

The microbial characteristics of four vegetated and one unplanted wood-chip bioreactors treating greenhouse effluent were investigated in a continuous experiment operated for over 2.5 years. The bioreactors were designed to reduce nitrate concentrations via naturally induced microbial denitrification. The vegetation type and reactor depth were both found to be significant factors in defining the mixed microbial activity. However, a consistent correlation between the abundance of the denitrifying communities and reactor depth could not be found across all reactors. The media samples from the unit planted with Typha angustifolia displayed higher microbial activities compared with the other reactors. This plant&rsquo, s root-associated bacteria also demonstrated the greatest copies of the denitrifying genes nirK and nosZ. The most abundant denitrifier communities and those encoding the nosZ gene were found in the unplanted reactor, followed by the T. angustifolia unit. The T. angustifolia reactor demonstrated greater microbial activity and denitrification capacity at the depth of 20 cm, while the greatest denitrification capacity in the unplanted reactor was found at the depth of 60 cm. These findings indicated the importance of the T. angustifolia rhizosphere to support microbial community establishment and growth in the vicinity of the plant&rsquo, s roots, although those populations may eventually develop in an unplanted environment.

Assessing the extent to which emerging contaminants (ECs) such as perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been released into the environment is one of the foundations for developing effective management and remediation strategies for impacted sites. PFAS are known to have caused the contamination of soil, groundwater, and surface water as a result of aqueous film forming foam (AFFF) being accidentally or intentionally released into the environment. To date, the scope of the issue has not been evaluated in Canada. In this study we developed a framework, in the form of a decision tree, to estimate the number of potentially PFAS impacted airport sites in Canada as a result of AFFF releases. The screening process was completed using publicly available resources including airport websites, the Canadian Owners and Pilots Association website, Sky Vector, Transport Safety Board of Canada aviation investigation reports, the Aviation Safety Network website, and Google maps. The methodology presented in this study could be used to identify additional PFAS impacted sites in Canada or other jurisdictions worldwide. 2071 airport/heliport sites in Canada were investigated with indications that 152 (7%) of these sites likely have PFAS contamination as a result of the use of AFFF at firefighter training areas (FFTAs) and/or accidents where fires occurred. In addition, another 268 sites (13%) were identified as possibly impacted with PFASs primarily as a result of the location having the ability to store and dispense petroleum products, and therefore having AFFF systems onsite. Surficial geology was also identified for all sites determined to likely have PFAS contamination. An estimated 42.8% had surficial geology composed of sand, 27% had clay, 19.7% organic-based, with the remaining sites found on cryosols or rock. Methodological validation was also completed. The procedure used in this study successfully predicted occurrences of PFAS contamination at 25 sites where contamination, as a result of AFFF use, was confirmed by Canadian governmental departments. For these 25 sites, the distance from potential release areas to the nearest surface water was calculated. Five of the sites were within 200 meters of surface water, 19 were within one kilometer, and all 25 were within 2.5 kilometers. This suggests that surface water may have been historically impacted by PFAS at as many as 152 to 420 different airport locations in Canada.

Analysis of water table fluctuations can provide important insight into the hydraulic properties and structure of a coastal aquifer system including the connectivity between the aquifer and ocean. This study presents an improved approach for characterizing a permeable heterogeneous coastal aquifer system through analysis of the propagation of the tidal signal, as well as offshore storm pulse signals through a coastal aquifer. Offshore storms produce high wave activity, but are not necessarily linked to significant onshore precipitation. In this study, we focused on offshore storm events during which no onshore precipitation occurred. Extensive groundwater level data collected on a sand barrier island (Sable Island, NS, Canada) show nonuniform discontinuous propagation of the tide and offshore storm pulse signals through the aquifer with isolated inland areas showing enhanced response to both oceanic forcing signals. Propagation analysis suggests that isolated inland water table fluctuations may be caused by localized leakage from a confined aquifer that is connected to the ocean offshore but within the wave setup zone. Two-dimensional groundwater flow simulations were conducted to test the leaky confined-unconfined aquifer conceptualization and to identify the effect of key parameters on tidal signal propagation in leaky confined-unconfined coastal aquifers. This study illustrates that analysis of offshore storm signal propagation, in addition to tidal signal propagation, provides a valuable and low resource approach for large-scale characterization of permeable heterogeneous coastal aquifers. Such an approach is needed for the effective management of coastal environments where water resources are threatened by human activities and the changing climate.

Bioremediation through the injection of electron donors and bacterial cultures is effective at treating chlorinated solvent contamination. However, it has had limited application in low permeability zones where amendments cannot be delivered successfully. This field-scale study investigated the application of electrokinetics to enhance the delivery of lactate at a clay site contaminated with chlorinated solvents. Groundwater and soil samples were collected before, during and for 1 year after the 71-day field test and analyzed for a wide suite of chemical and biological parameters. Lactate was successfully delivered to all monitoring locations. Lactate emplacement resulted in the stimulation of bacterial populations, specifically within the phylum Firmicutes, which contains fermenters and strict anaerobes. This likely led to biodegradation, as the field trial resulted in significant decreases in both soil and aqueous phase chlorinated solvent concentrations. Contaminant decreases were also partially attributable to dilution, given evidence of some advective lactate flux. This research provides evidence that electrokinetically-enhanced bioremediation has potential as a treatment strategy for contaminated low permeability strata.

The objective of this research was to study the differences in microbial community metabolic function in planted and unplanted saturated constructed wetland mesocosm systems with five different wetland plant species, Typha latifolia, Phragmites australis, Iris pseudacorus, Berula erecta and Juncus effusus treating the pesticides imazalil and tebuconazole. Community level physiological profiling (CLPP) was used to determine the microbial community metabolic function from each mesocosm. Microbial activity and metabolic richness were in general not differentiated by pesticides presence. Significantly lower values in comparison with a non-pesticide control were only found in the Iris mesocosms exposed to imazalil and tebuconazole and in the Berula mesocosms exposed to tebuconazole during winter. Planted mesocosms had different microbial community carbon source utilization patterns in comparison to the unplanted mesocosms. In comparison to pesticide presence, plant species had a larger effect on differentiating the microbial community carbon source utilization patterns. Seasonal effects on carbon source utilization patterns were observed for both planted and unplanted mesocosms. In summer, microbial activity and metabolic richness were negatively correlated with TN, NH4+-N, TP concentration and pH in the control group, but not in the pesticide treatment groups, again suggesting a microbial community functional shift in the presence of pesticides. The main factors driving microbial community activity and functional diversity were plant species and season, while carbon source utilization revealed some pesticide adaptation in the summer period.

The aim of the present study was to elucidate the microbial community metabolic profiles in saturated constructed wetland (CW) mesocosms planted with five different wetland plant species fed with water individually spiked with 100 μg L-1 ibuprofen or iohexol. Community-level physiological profiling (CLPP) using Biolog Ecoplates was performed and coupled with the assessment of water quality parameters (water temperature, pH, DO and TOC, TN, NH4-N, PO4-P removal efficiency). The microbial community metabolic profiles (microbial acitivity, richness, and carbon source utilization), as well as the water quality parameters revelead similar trends among the control mesocosms and the mescocosms fed with water spiked with iohexol and ibuprofen. Significant differences were observed between the planted and unplanted mesocosms and between seasons (summer and winter) within each of the feeding lines (control, iohexol or ibuprofen). The microbial community metabolic profiles in the saturated CW were shaped by plant presence and plant species, while no impact of iohexol and ibuprofen presence was noticed at the 100 μg L-1. In addition, the microbial activity and richness were generally higher in planted mesocosms than in the unplanted systems in the summer. For the first time, a positive correlation between iohexol removal and the microbial community metabolic profiles (activity, richness and amines and amides utilization in summer, and carbohydrates utilization in winter) in the saturated mesocosms was observed. Biodegradation was a main driver for iohexol and ibuprofen removal. Putrescine utilization in the summer and D-cellobiose, D,L-alpha-glycerol phosphate in winter were linked with the metabolic processing of iohexol, while glycogen in summer and L-phenylalanine, Glycyl-L-glutamic acid in winter linked with the ibuprofen removal efficiency in the saturated CW.

Silver nanoparticles (AgNPs) are increasingly used as an antimicrobial agent in various consumer products. Silver release from these products occurs during use, washing and disposal at varying rates, into the wastewater system and eventually into aquatic ecosystems. Constructed wetlands (wetlands designed for water pollution control) represent a unique type of water treatment system which are beginning to receive growing amounts of influent AgNP loadings. In order to examine potential impacts to the health and ongoing utility of constructed wetlands we evaluated the susceptibility and the developed resistence of constructed wetland microbial communities to two types of AgNPs (citrate and polyvinylpyrrolidone (PVP)-coated), and ionic Ag (Ag+). Microcosms representing an unplanted batch-fed subsurface flow constructed wetland were exposed to an AgNP contaminated (100 mu g/l) simulated wastewater for 28 days. Experiments were triplicated and included unexposed controls. Analysis of total Ag in the interstitial water and biofilm matrix via inductively coupled plasma mass-spectrometry (ICP-MS) revealed the majority (>98%) of AgNPs partitioned from the interstitial water and accumulated in the biofilm and presumably the sediment matrix. No significant alteration to the microbial community function (assessed via community-level physiological profiling, CLPP) or structure (using denaturing gradient gel electrophoresis, DGGE) was observed following the initial 28 day exposure. Subsequent ex-situ dose-response testing over a wide concentration range (0-5 mu g/l) provided some evidence for increased resistance to Ag toxicity in the previously exposed microbial communities when compared to the controls. The ex-situ evaluated susceptibility of the microbial communities to AgNPs varied between treatments with significant reductions in catabolic activity observed at 0.5 mg/l for ionic Ag, 1 mg/l for citrate coated AgNPs and 5 mg/l for PVP coated AgNPs. These findings suggest that wetland microbial communities can tolerate and develop resistance to lower levels of in-situ AgNP exposure in a relatively short time, however ex-situ toxicity is observed past certain threshold concentrations and this threshold varies depending on the original form of the AgNP. (C) 2016 Elsevier B.V. All rights reserved. This work was financially supported by the Erasmus Mundus programme IMETE (Ghent University, Belgium) and COST action ES1205. The authors thank Nico Boon for access to the Laboratory of Microbial Ecology and Technology (LabMET) and for fruitful discussions. Support from NSERC in the form of a Discovery and an SPG grant to KPW is gratefully acknowledged. We would also like to thank Tim Lacoere for his help with the molecular techniques, Xiao Yi for help with CLPP and Quenten Denon for the assistance with the PCS analysis.

Both the presence and diversity of plants are integral to the development and functional abilities of microbial communities within constructed wetlands (CWs). The aim of this study was to assess the impacts of different individual and paired plant species combinations on microbial community function in HSSF mesocosm CWs. Experimental systems were quadruplicated and operated as two mesocosms in series planted with Phragmites australis (X) or Phalaris arundinacea (O), giving four possible sequential combinations (XX, XO, OX, OO). Wastewater was loaded each day into position 1 mesocosm with the outflow entering position 2 mesocosm, and the corresponding position 2 mesocosm outflow representing an overall experimental system effluent. The metabolic function of the interstitial-based microbial communities within each of the 16 mesocosm pairs was assessed at a single time point in the spring (May) based on community-level physiological profiles (CLPPs) gathered using Biolog ® EcoPlates. Microbial activity and metabolic richness (number of carbon sources utilised) were found to be higher in position 1 mesocosms compared to position two. Microbial community carbon source utilisation patterns (CSUPs), overall activity and metabolic richness were similar between all mesocosms from position 1—irrespective of plant species. When assessing microbial communities in position 2 of each pairing a greater variety of CSUPs, activities and metabolic richness' could be found suggesting the sequence and choice of plant can alter the microbial community function in the HSSF mesocosms. Of particular interest were the mesocosm/plant species combinations containing Phalaris in the position 2 which led to higher overall microbial activity and richness, distinct carbon source utilisation patterns (CSUPs) and an increased utilisation of specific carbon sources further from the inlet. More specifically the XO pairings ( Phragmites-Phalaris ) seemed to offer the most promising overall microbial function throughout both positions 1 and 2 in series suggesting plant diversity may help enhance microbial community function, and therefore microbial based water treatment capacity. The findings also suggest that the microbial communities associated with each plant species respond differently to factors such as nutrient availability, and although not yet clearly defined, further highlights the potential for improved or tailored water treatment in CWs through selection of specific plant species and combinations. Broader microbial community function or greater activity did not correlate with improved water treatment efficiency in this study. This may have been due to the relatively low contaminant loads utilised, or the limited amount of data collected. Further study across several seasons or with higher contaminant loads is recommended.

Microorganisms are central to the biogeochemical processes in constructed treatment wetlands. In this study we explored the spatial dynamics of microbial community metabolic function in several different constructed treatment wetland designs at the pilot-scale constructed wetlands of the UFZ Ecotechnology Research Facility in Langenreichenbach, Germany. The constructed wetland designs differed in terms of flow direction, degree of saturation, depth, and intensification. Internal sampling was conducted in April 2013 at different locations along the flow path of each system. The microbial community metabolic function was characterized via community level physiological profiling (CLPP). Microbial community activity (substrate utilization rate) and metabolic richness (number of carbon sources utilize) decreased dramatically with increasing distance along the flow path for most systems. Variation in the metabolic function of microbial communities was observed based on carbon source utilization patterns (CSUPs) and was found to be strongly influenced by system design and sample location within the wetland but not by the presence of plants or depth of media. Analysis of specific carbon source guilds highlighted increased utilization of polymers and carbohydrates in the early stages of all systems, pointing to the establishment of microbial communities optimized to best utilize more easily degradable compounds close to the inlet. Correlations between measures of microbial functionality (activity, richness, and diversity) and turbidity, total organic carbon (TOC), total nitrogen (TN) were observed in horizontal-flow systems but less so in vertical-flow systems. The results presented provide useful insight into the spatial dynamics of microbial community function in constructed wetlands. Potential opportunities for system optimization, based on the results of this study, are provided.

A robust computational fluid dynamics (CFD) model accounting for both spatial and temporal dynamics of a subsurface vertical flow treatment wetland system was developed by combining fluid transport, solute transport, biokinetics, biofilm development, and biofilm detachment/sloughing using COMSOL Multiphysics™. The local porosity of the porous media was calculated based on the estimated biofilm development over time. The biofilm development sub-model considered both organic pollutant metabolism/degradation as a mechanism for microbial growth and the effect of fluid shear stress on the local biofilm detachment. The influence of biofilm accumulation on the permeability of the porous media was considered using the Kozeney–Carman relation. The permeability of the porous media was estimated by calibrating the model against experimental tracer data that had been collected in a full water-recirculation batch operation. As the biofilm developed from start-up, removal efficiency of readily biodegradable organic matter improved during the first 10 weeks of operation while no significant change was predicted after 10 weeks. A dead-zone region was predicted near the bottom of the system opposite to the outflow port after 100 days of operation attributed to exponential biofilm growth and low biofilm detachment rates. A decrease of 95% in the advective transport of organic matter in the dead-zone region occurred after 280 days of operation. No appreciable biofilm accumulation was predicted in the region near the outlet due to the high fluid shear stress acting on the biofilm surface. The averaged porosity of the mesocosm decreased by 6.6% after 365 days of operation while the local porosity in the dead-zone region decreased by 71%. Good agreement was found between the averaged porosity of the entire system and experimental data. This is the first model to integrate hydrodynamics, solute transport, biokinetics relating to pollutant removal, biofilm development, and biofilm detachment into a comprehensive model. Although computationally intensive, this is the first model to predict bio-clogging processes in a spatial manner similar to what would be realistically expected.

Microbial degradation is an important pathway during the removal of pharmaceuticals in constructed wetlands (CWs). However, the effects of CW design, plant presence, and different plant species on the microbial community in CWs have not been fully explored. This study aims to investigate the microbial community metabolic function of different types of CWs used to treat ibuprofen via community-level physiological profiling (CLPP) analysis. We studied the interactions between three CW designs (unsaturated, saturated and aerated) and six types of mesocosms (one unplanted and five planted, with Juncus, Typha, Berula, Phragmites and Iris) treating synthetic wastewater. Results show that the microbial activity and metabolic richness found in the interstitial water and biofilm of the unsaturated designs were lower than those of the saturated and aerated designs. Compared to other CW designs, the aerated mesocosms had the highest microbial activity and metabolic richness in the interstitial water, but similar levels of biofilm microbial activity and metabolic richness to the saturated mesocosms. In all three designs, biofilm microbial metabolic richness was significantly higher (p

The objective of this study was to investigate if the catabolic capabilities (the overall ability to utilize a wide range of carbon sources) and catabolic profiles (the overall pattern of carbon source usage based on the carbon source types and relative usage extent) of microbial communities in free-floating plant treatment wetlands differ based on the presence or combination of different plant species. Free Floating-plant treatment wetland mesocosms were established using four different plant species: Limnobium laevigatum (L), Salvinia molesta (S), Eichhornia crassipes (E), and Pistia stratiotes (P). Mesocosms were either arranged as a monoculture (one plant species), biculture (two different plant species; all possible pairings), or quadricultures (one of each plant species). Mesocosms were fed twice weekly with 20 L of reconstituted wastewater using diluted fish farm sludge effluent. The microbial communities in each mesocosm were assessed after a 4 month operational period using the community level physiological profiling (CLPP) method. It was observed that monoculture wetland systems had different catabolic activities and catabolic richness’ (number of carbon sources utilized) with the following respective trends: (L) > (P) = (S) > (E) and (L) > (E) = (P) > (S). It was also found that the carbon source utilization patterns of the microbial communities from the monoculture mesocosms were distinctly different from each other, and that the polyculture communities were different from the respective monoculture counterparts. These findings further support the hypothesis that plant type and combination plays a critical role in the development of the microbial communities present in treatment wetlands. It was also found that increasing the number of plant species did not, on average, promote the development of microbial communities with a more active and diverse catabolic capability, but rather specific plant selection and plant/plant interactions were important. In comparison to the other plant species E. crassipes had the largest amount of root mass available for microbial community attachment. Observations suggested that this larger root mass translated into E. crassipes having a dominating effect on defining the carbon source utilization patterns of microbial communities from polyculture mesocosms. Although microbial communities from the monoculture mesocosms containing E. crassipes had the lowest activities (on a per unit volume basis), E. crassipes mesocosms generally had the best COD removal rates in either monoculture or polyculture systems, potentially because of the greater amount of root mass available.

Microbial communities play a vital role in maintaining soil health. A multiphasic approach to assess the effect of pulp and paper mill effluent on both the structure and function of microbial soil communities is taken. Bacterial communities from agricultural soils irrigated with pulp and paper mill effluent were compared to communities form soils irrigated with well water. Samples were taken from fields in the state of Uttarakhand, India, where pulp and paper mill effluent has been used for irrigation for over 25 years. Comparisons of bacterial community structure were conducted using sequencing of the 16S rRNA gene from both isolates and clone libraries attained from the soil. Community-level physiological profiling was used to characterize the functional diversity and catabolic profile of the bacterial communities. The multiphasic approach using both physiological and molecular techniques proved to be a powerful tool in evaluating the soil bacterial community population and population differences therein. A significant and consistent difference in the population structure and function was found for the bacterial communities from soil irrigated with effluent in comparison to fields irrigated with well water. The diversity index parameters indicated that the microbial community in pulp and paper mill effluent irrigated fields were more diverse in both structure and function. This suggests that the pulp and paper mill effluent is not having a negative effect on the soil microbial community, but in fact may have a positive influence. In terms of soil health, this finding supports the continued use of pulp and paper mill effluent for irrigation. This is however only one aspect of soil health which was evaluated. Further studies on soil resistance and robustness could be undertaken to holistically evaluate soil health in this situation.

Microbial communities play a critical role in degrading organic contaminants in treatment wetlands; however, an understanding of the different roles played by rhizospheric, gravel-associated and interstitial microbial communities is deficient due to a lack of data directly comparing these microbial communities. Community level physiological profiling (CLPP) was used to compare the catabolic capabilities of rhizospheric, gravel-associated and interstitial microbial communities in vertical-flow planted and unplanted wetland mesocosms. Wetland mesocosms were decommissioned to gather microbial community samples associated with the roots and gravel bed media taken from the top (10 cm depth), middle (30 cm depth) and bottom (60 cm depth). The catabolic capabilities of the rhizospheric microbial communities were seen to be much greater than those of the gravel-associated communities. A decrease in catabolic capability was seen with increasing depth, suggesting that communities near the surface play a larger role in the degradation of carbon-based compounds. A general difference in catabolic profiles based on plant presence/absence was observed for the interstitial water and all gravel-associated samples at all depths, suggesting that the presence of roots within part of the mesocosm not only has a localized effect on the attached microbial population, but also on gravel-associated microbial communities throughout the mesocosms.

In this study, the effect of the antibiotic ciprofloxacin on the presentation and potential development of antibiotic resistance among selected faecal indicators (Escherichia coli and Enterococcus spp.) and the intrinsic bacterial community for a freshwater model ecosystem was investigated. Four parallel mesocosm wetlands planted with Phragmites australis were initially seeded with an activated sludge inoculum from a wastewater treatment plant and monitored over the course of 63 days. Two of the four mesocosms (CIP1 and CIP2) were initially exposed to a ciprofloxacin concentration of 2 μg mL−1 for a 5 day period, and two were considered controls (CON1 and CON2). Minimum inhibitory concentrations were determined for the culturable interstitial microbial community using ciprofloxacin concentrations ranging from 0.5 to 16 μg mL−1 and compared with total heterotrophic plate counts (HPCs). E. coli and Enterococcus spp. were enumerated and screened for antimicrobial resistance to twelve different antibiotics both before and after mesocosm ciprofloxacin exposure. Concentrations for total heterotrophs within the interstitial water were in the order of 106–108 CFU 100 mL−1, while E. coli and Enterococcus spp. were present in lower concentrations, at 102–103 CFU 100 mL−1. All four mesocosms had the same minimum inhibitory concentrations (MICs) of 2 μg mL−1 for total heterotrophic community during the first week of start-up (before ciprofloxacin exposure), followed by a sharp increase in ciprofloxacin exposed mesocosms on day 14 (after ciprofloxacin exposure), reaching a maximum MIC of 16 μg mL−1. The resistance levels of interstitial heterotrophic counts determined by the agar dilution method peaked 7 days following the ciprofloxacin exposure, and decreased thereafter. A significant increase (p < 0.05) to the following antibiotics was observed among E. coli following ciprofloxacin exposure within mesocosm CIP2: ciprofloxacin (CIP), chloramphenicol (C), cefotaxime (CTX), ceftriaxone (CRO), and doxycycline (D). These results illustrate the potential for a single antibiotic exposure event to create a noticeable increase in the antibiotic resistance profile, not only to the imposed antibiotic, but to other classes of antibiotics. The initial background levels of resistance among Enterococcus spp. were significantly higher than those observed among E. coli, exhibiting a combined average of 96%, 96%, and 100% resistance to ciprofloxacin (CIP), linezolid (LZD), and streptomycin (S), respectively. Following the addition of ciprofloxacin, Enterococcus spp. retained high levels of resistance to ciprofloxacin, linezolid, and streptomycin, with a significant increase (p < 0.05) to vancomycin (VA), reaching 100% on Day 63. The findings of this study suggest that the transient presence of an isolated exposure event of ciprofloxacin can impact the antibiotic resistance profiles among faecal indicators in lab-scale constructed mesocosms and has the potential to impact constructed wetland treatment systems.

The objective of this work was to study the effect of plant presence ( Phragmites australis ) and inoculant origin on wetland mesocosm start-up dynamics. Eight mesocosms were studied based on a duplicated 2 2 factorial design tracking bacterial community and hydrological changes during an 8 month start-up period. The mesocosms were characterized in terms of their hydrological character based on evapotranspiration (ET), porosity, and a dispersion coefficient. The microbiological regime was characterized using a microbial activity measure and community-level physiological profiling (CLPP) employing BIOLOG™ ECO plates. CLPP-related indices such as substrate richness, substrate diversity, over-all community profile, and community divergence are also presented. It was found that mesocosm porosities decreased over time as a result of media-related biofilm development. This biofilm development also contributed to a substantial increase in the dispersion coefficient in the mesocosms over the start-up period. Dispersion coefficients in planted systems reached values of ∼50–55 cm 2 /min whereas in the unplanted systems values of ∼30–35 cm 2 /min were observed. Bacterial community divergence in the mesocosms was quantified using a Euclidean-based divergence metric. All mesocosms showed a sharp increase in community divergence until day 75, at which point a steady state was reached. The interstitial communities were also characterized in terms of similarity based on the experimental design treatments. Four stages of mesocosm development were identified that can be described by an initial community state based on the origins of the initial inoculum [days 0–6]; a dynamic period where adjustments and shifts in the bacterial community occurred in all mesocosms [days 7–26]; a period where all interstitial CLPPs were quite similar [days 27–73]; and finally a shift towards unplanted and planted mesocosm CLPP groupings [days 74–232].

Nano-scale zero valent iron (nZVI) has been used at a number of contaminated sites over the last decade. At most of these sites, significant decreases in contaminant concentrations have resulted from the application of nZVI. However, limited work has been completed investigating nZVI field-scale mobility. In this study, a field test was combined with numerical modeling to examine nZVI reactivity along with transport properties in variably saturated soils. The field test consisted of 142L of carboxymethyle cellulose (CMC) stabilized monometallic nZVI synthesized onsite and injected into a variably saturated zone. Periodic groundwater samples were collected from the injection well, as well as, from two monitoring wells to analyze for chlorinated solvents and other geochemistry indicators. This study showed that CMC stabilized monometallic nZVI was able to decrease tricholorethene (TCE) concentrations in groundwater by more than 99% from the historical TCE concentrations. A three dimensional, three phase, finite difference numerical simulator, (CompSim) was used to further investigate nZVI and polymer transport at the variably saturated site. The model was able to accurately predict the field observed head data without parameter fitting. In addition, the numerical simulator estimated the mass of nZVI delivered to the saturated and unsaturated zones and distinguished the nZVI phase (i.e. aqueous or attached). The simulation results showed that the injected slurry migrated radially outward from the injection well, and therefore nZVI transport was governed by injection velocity and viscosity of the injected solution. A suite of sensitivity analyses was performed to investigate the impact of different injection scenarios (e.g. different volume and injection rate) on nZVI migration. Simulation results showed that injection of a higher nZVI volume delivered more iron particles at a given distance; however, the travel distance was not proportional to the increase in volume. Moreover, simulation results showed that using a 1D transport equation to simulate nZVI migration in the subsurface may overestimate the travel distance. This is because the 1D transport equation assumes a constant velocity while pore water velocity radially decreases from the well during injection. This study suggests that on-site synthesized nZVI particles are mobile in the subsurface and that a numerical simulator can be a valuable tool for optimal design of nZVI field applications.

The field of treatment wetlands (TWs) is rapidly expanding and, arguably, is tasked with studying and understanding one of the most complex water treatment systems available. Microbial communities are generally considered to be responsible for the majority of wastewater constituent degradation in TWs. However, they are also known to be spatially heterogeneous, temporally dynamic, as well as structurally and functionally diverse. Presented here is a meta-analysis of all peer reviewed TW journal articles which utilized a microbial community assessment methodology over the period of 1988 to July 2016. A total of 1101 papers were reviewed, 512 from 1988 to 2012, 215 of which included a microbial community assessment aspect and were subsequently classified as representing past research, and 589 from 2013 to July 2016, 196 of which were classified as representing current TW microbial community research. In general, TW microbial community research has increased over time, with a marked surge in the past four years. Microbial community structure is currently the most commonly used methodological type followed by activity, enumeration and function, respectively. Areas of research focus included nitrogen transformations (156), organic degradation (33), and emerging contaminants (32), with general characterization studies also accounting for a significant proportion (243). Microbial communities from a range of TW systems have been investigated over the last four years with meso-scale (10–1000 L) being the most commonly studied system size followed by large-scale (>100,000 L), micro-scale (