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Au cours des dernières décennies, une grande variété de pesticides émergents, tels que le chlorantraniliprole (CAP), ont été introduits malgré le manque de connaissance approfondie de leur risque écotoxicologique. Les marais filtrants (TW) sont des technologies écologiques et durables qui ont montré un grand potentiel d’atténuation des polluants agricoles communs, tels que les pesticides dans le ruissellement. L’objectif de cette étude était d’optimiser l’utilisation du marais filtrant sous-surfacique à écoulement horizontal (HSSF) en déterminant: a) l'effet d’un amendement de biochar au substrat et b) la performance de trois espèces de macrophytes (Phragmites australis subsp. americanus, Scirpus cyperinus et Sporobolus michauxianus) dans l'abattement du CAP du ruissellement agricole. L'efficacité d'abattement a été calculée en utilisant la méthode du bilan de masse dans des mésocosmes HSSF matures alimentés avec un ruissellement agricole synthétique contenant du CAP pendant une période d'un mois. Les mésocosmes avec l’ajout de biochar se sont avérés très efficaces dans l’abattement du CAP (90 à 99%) et ils le sont restés tout au long de la période expérimentale. Cette efficacité est probablement due à la grande capacité d’adsorption du biochar, bien que ce mécanisme n’ait pas été directement mesuré. En revanche, l'abattement du CAP dans les mésocosmes plantés sans biochar était faible et limité et il n’y avait pas de différence entre les espèces, bien qu’elles aient eu des différences dans leur biomasse aérienne et leur taux d'évapotranspiration (ET). Cependant, les traitements plantés ont agi comme zone tampon, en atténuant la masse du CAP de l'influent et en la libérant lentement dans l'effluent. Le taux d'ET de Scirpus et Phragmites était plus élevé que celui de Sporobolus, ce qui s’est traduit par un meilleur effet tampon. Cette étude suggère que l'ajout de biochar au substrat HSSF TW est prometteur pour l'atténuation du CAP dans le ruissellement agricole, mais leur efficacité à long terme reste à être étudiée. Malgré tout, les TW devraient être utilisés comme un outil complémentaire, dans le cadre d'actions plus larges visant à réduire la pression des polluants sur les écosystèmes aquatiques., Over the past decades, a wide variety of emergent pesticides, such as chlorantraniliprole (CAP), have been introduced despite the lack of in-depth knowledge of their ecotoxicological risk. Treatment wetlands (TWs) are environmentally friendly and sustainable technologies that have shown great potential to mitigate common agricultural pollutants, such as pesticides in runoff. The objective of this study was to optimize the use of the horizontal subsurface flow treatment wetlands (HSSF TWs) by determining a) the effect of biochar amendment to the substrate and b) the performance of three species of macrophytes (Phragmites australis subsp. americanus, Scirpus cyperinus and Sporobolus michauxianus) in CAP removal from agricultural runoff. The removal efficiency was calculated using the mass balance method in mature HSSF mesocosms fed with synthetic agricultural runoff containing CAP for a period of one month. Mesocosms with the addition of biochar were very effective in removing CAP (90-99%) and remained so throughout the experimental period. This efficiency is likely due to the high adsorption capacity of biochar, although this mechanism has not been directly measured. In contrast, CAP removal in mesocosms planted without biochar was low and limited and there was no difference between species, although there were differences in their above-ground biomass and their evapotranspiration (ET) rate. However, the planted mesocosms acted as buffer zones, reducing the CAP mass of the influent and slowly releasing it into the discharge. The ET rate of S. cyperinus and P. australis was higher than that of S. michauxianus, resulting in a better buffering effect. This study suggests that adding biochar to the HSSF TW substrate is promising for CAP attenuation in agricultural runoff, but their long-term effectiveness remains to be investigated. Nevertheless, TWs should be used as a complementary tool, as part of wider actions aimed at reducing the pressure of pollutants on aquatic ecosystems.

Green cooling towers, or thermal green-walls, recirculate hot water flowing through a living plant and porous material. Through convective and evaporative heat and mass transfer they can actively cool a building or an industrial heat waste. Thus they can provide an alternative cooling technology. Thermal green-walls use wetland plant species in highly constructed wetlands selected for their heat tolerance. In addition, they offer such co-benefits as carbon capture and control of local microclimates. Optimal heat rejection (HR) requires the plant rhizosphere to be completely inundated at temperatures much higher than the ambient air temperature, potentially inducing thermal physiological stress. To study the viability of specific plants within a HR system, we exposed three macrophytes, Iris versicolor, Scirpus cyperinus and Carex lurida, to hydroponic recirculating water at three different temperatures (25 °C, 35 °C, and 40 °C). We assessed the plant responses over a period of eight weeks by measuring photochemical efficiency, leaf temperature, stomatal conductance, G s and biomass output. Plant biomass was highest at 35 °C (particularly in I. versicolor), even higher than ambient water temperature at 25 °C. We observed a general homeothermic-like response in G s over a 5-week time period, but the response was species-specific with respect to temperature. Results suggests a possible leaf-level physiological acclimation mechanism as well as high maintenance of tissue moisture that allows macrophytes to tolerate hydro-thermal stress, and support their suitability to perform in HR systems at input temperature, T win = 35 °C.

There are very few studies on the spontaneous revegetation of cutover fens or bogs from which peat has been extracted to the minerotrophic layers. Most peatlands with fen-type residual peat have problems regenerating a plant cover satisfactorily from a restoration point of view. We nevertheless found a site (Moss Spur, Manitoba, Canada) presenting a substantial and diversified spontaneous plant cover. We estimated that the site would provide insights about natural revegetation processes operating in peatlands. Vegetation assemblages and environmental conditions were surveyed 19 years after extraction activities ceased. Moss Spur has densely revegetated (163 plant species, vegetation cover of 94%) with minimal human assistance. However, the composition of plant assemblages varies considerably across the site, depending on certain abiotic variables, particularly water pH, water table level, and the thickness of the residual peat layer. Moss Spur was remarkably wet considering the past peat extraction activities and the absence of active rewetting procedures. The high water table level may in part explain the successful revegetation. However, plant assemblages were not of equal quality from a restoration perspective. Some assemblages were highly diversified, and especially those dominated by Scirpus cyperinus, a species that should be further considered in peatland restoration projects to direct the recovery of the peatland towards a natural fen species composition.

Chlorantraniliprole (CAP), an emergent insecticide commonly replacing banned neonicotinoids, is used worldwide despite the risk of contaminating water bodies. Treatment wetlands (TWs) have shown great potential for mitigating various pesticides in agricultural runoff, but little is known about CAP removal. The aim of this study was to determine the effect of adding biochar to subsurface flow treatment wetlands (SSF TWs) and the performance of three macrophyte species (Phragmites australis subsp. americanus, Scirpus cyperinus and Sporobolus michauxianus) in CAP removal. Removal efficiency was monitored over a one-month period in water-saturated SSF mesocosms fed with synthetic agricultural runoff containing CAP. To reflect temporal changes in agricultural runoff dynamics, two CAP concentrations were used in influent: a peak concentration (4 μg/L) for the first week and a trace concentration (0.4 μg/L) for the three subsequent weeks. Results showed that mesocosms with biochar were very effective in removing CAP mass (90 to 99%) and remained so throughout the experimental period. On the other hand, the level of CAP removal achieved in planted mesocosms without biochar was low (less than 13%). Evapotranspiration contributed significantly to volume reduction, but no general pattern in CAP mass removal efficiency was detected among the planted treatments without biochar. However, planted treatments acted as buffer zones, accumulating CAP and reducing its peak mass in effluent. Evapotranspiration rates of Scirpus and Phragmites were higher than that of Sporobolus, resulting in a greater buffering effect. This study suggests that addition of biochar to SSF TW substrate is a promising approach for CAP mitigation in agricultural runoff, but long-term efficiency remains to be assessed.

Previous information on host plants of the blissid Ischnodemus rufipes Van Duzee has been limited to single observations in Florida on each of two sedges (Cyperaceae): Cyperus erythrorhizos and C. odoratus. In the piedmont of South Carolina, during extreme drought conditions in August 2008, I. rufipes was found on redroot flatsedge, C. erythrorhizos, which had colonized mudflats on exposed shorelines of Hartwell Lake in Clemson. Surveys to determine the host-plant range of I. rufipes were conducted from 2008 to 2012 in the Blue Ridge ecoregion of Georgia and North Carolina and coastal plain and piedmont of Georgia and South Carolina. The blissid exploits the short (floriferous) growth form of C. erythrorhizos, an annual sedge of unpredictable availability in ephemeral mudflats, while maintaining populations mainly on a perennial sedge, Scirpus cyperinus, in more persistent habitats. The blissid also develops on the generally taller C. erythrorhizos plants in more permanent wetlands. Only one gen...

As the use of constructed storm water wetlands to treat storm water runoff becomes more frequent, strategies for maintaining or increasing their pollutant removal over time must be examined. One potential strategy is plant harvesting at the water surface to remove nutrients that would otherwise be deposited back into the wetland during senescence. This technical note presents a first look at this strategy from a storm water management perspective. Vegetation was harvested from two storm water wetlands located in Smithfield and Pactolus, North Carolina, to evaluate the ability of five wetland plant species to sequester nitrogen. Biomass samples were collected from the following species of emergent vegetation: Pontederia cordata (Pickerelweed), Saururus cernuus (Lizard Tail), Scirpus cyperinus (Wool Grass), Sagittaria latifolia (Arrowhead), and Schoenoplectus tabernaemontani (Softstem Bulrush). Samples were collected immediately prior to senescence in September and October 2007 and analyzed for nitr...

We examined patterns of methane flux, plant biomass, and microbial methanogenic populations in nine wetland plant species. Methane dynamics varied across plant functional groupings, with patterns distinctive among forbs, clonal dominants, and tussock/clump-forming graminoids. Carex stricta and Scirpus atrovirens showed the highest emissions (31.7 and 20.6 mg CH4-C m−2 h−1), followed by other tussock- or clump-forming graminoids that averaged 11.0 mg CH4-C m−2 h−1 (Scirpus cyperinus, Glyceria striata, and Juncus effusus). The clonal dominants (Phalaris arundinacea and Typha angustifolia) had the lowest methane emissions (1.3 and 3.4 mg CH4-C m−2 h−1) of all seven graminoid species, and the forbs (Mimulus ringens and Verbena hastata) emitted no detectable methane flux from their leaves. In general, methane emissions decreased with greater plant biomass. Terminal restriction fragment analysis (T-RFLP) of archaeal 16S rRNA revealed that the structure of the soil methanogen communities isolated from plant rhizospheres had no effect on methane flux. The relative proportions of the different terminal fragments were not correlated with either methane emissions or plant biomass. Methanogen populations from J. effusus soils were dominated by acetoclastic archaea of the Methanosarcinaceae and Methanosaetaceae families, while all other graminoid soils were colonized primarily by hydrogenotrophic archaea of the Methanobacteriaceae family. The results indicate that plant functional groups and plant biomass are useful in predicting methane flux differences across plant species, while soil methanogen community structure showed no distinguishable patterns.

Reed canary grass (Phalaris arundinacea) invasion is prevalent in wetlands and riparian fringes, and due to differences in vegetative growth and residue quality relative to native species, P. arundinacea invasion could result in measurable effect on soil organic carbon (SOC) pools and composition. To examine these questions, plant biomass and soil samples were collected from areas invaded by P. arundinacea and areas colonized either by a native sedge Scirpus cyperinus or a mixed assemblage of 22 native species in a south-central Indiana (USA) wetland. Plant biomass composition (C, N, cellulose, lignin, and phenolics), total and water-extractable SOC pools were determined. S. cyperinus biomass contained (g kg−1 biomass) significantly (P

Thousands of depressional wetlands accidentally formed as a result of pre-1977 contour coal mining in the Appalachian Mountains. Eleven 20-yr old sites were found in a watershed that did not receive acid mine drainage. The purpose of this study was to quantify and model above- and below-ground plant biomass in these created wetlands and to evaluate functional development. Sampling was stratified by weighted average of two plant communities, which corresponded to shallower and deeper water levels, facultative wetland and obligate wetland communities, respectively. In 1994, peak above-ground biomass averaged 473.7 g m−2 in the facultative wetland community and 409.5 g m−2 in the obligate wetland community. Scirpus cyperinus exhibited the highest peak above-ground biomass (51.8% of total biomass) and Typha latifolia ranked second. Canonical correspondence analysis detected positive effects of longer soil exposure to the atmosphere and greater sediment depth on above-ground biomass at the site (wetland ecosystem) level. Within communities, forward stepwise regression identified positive association of above-ground biomass with water soluble reactive P, water soluble NH3, decomposition rate over 507 d, live S. cyperinus tissue P content, and sediment depth. When these results are combined with prior studies conducted at the same 20-yr old sites, it appears that both structural and functional development has been arrested at a somewhat immature state resulting primarily from soil and hydrologic factors.

Random Amplified Polymorphic DNA (RAPD) markers were used to determine whether populations of the global rarity Scirpus longii (Long's bulrush) are vulnerable to loss by introgression of genetic material from the weedy S. cyperinus (woolgrass). Shoots from 104 Scirpus plants were obtained from 10 sites in the watershed of the lower Medway River in Nova Scotia, Canada. A putative site of introgression (a seasonally flooded bog) was divided into five subsites: one large stand of vegetative plants and four patches of annually flowering plants clustered at one end of the site. Thirty-five dominant DNA markers were found among individuals from all sites and eight species-specific markers were identified for each of the two species. Nineteen different combinations of species-specific markers were present in the 39 individuals from the site of introgression, and, as expected for introgression, there was strong correlation (r = −0.80, p < 0.0001) between the numbers of the two types of markers. The veg...

Reed canary grass (Phalaris arundinacea, L.) invasion of wetlands is an ecological issue that has received attention, but its impact on soil microbial diversity is not well documented. The present study assessed the size (substrate-induced respiration), catabolic diversity (CLPP, community level physiological profiles) and composition (selective inhibition) of the soil microbial community in invaded (>95% P. arundinacea cover) and in non-invaded areas of a wetland occupied by native species grown either as a mixed assemblage (22 species) or as quasi-monotypic stands of Scirpus cyperinus (74% cover). The study also tested the hypothesis that decomposition of lignin- and phenolics-rich plant tissues would be fastest in soils exhibiting high catabolic diversity. Results showed that soil respiration, microbial biomass and diversity were significantly higher (P < 0.03; 1.5 to 3 fold) in P. arundinacea-invaded soils than in soils supporting native plant species. Fungal to bacterial ratios were also higher in invaded (0.6) than in non-invaded (0.4) plots. Further, canonical discriminant analysis of CLPP data showed distinct communities of soil decomposers associated with each plant community. However, these differences in microbial attributes had no effect on decomposition of plant biomass which was primarily controlled by its chemical composition. While P. arundinacea invasion has substantially reduced plant diversity, this study found no parallel decline in the size and diversity of the soil microbial community in the invaded areas.

A surface flow constructed wetland, designed to curve in a kidney shape in order to increase the length to width ratio to 5:1 was used to treat runoff from an industrial park. A natural wetland system located approximately 200 m downstream of the constructed wetland was selected to act as the vegetative community model for the constructed wetland. The selected model was a riparian, open water marsh dominated by emergent macrophytes. Baseline plant species surveying was conducted. In total, 21 emergent wetland plant species, 40 upland vascular plant species, 17 upland shrub species and 13 upland tree species were identified in the model site. The species from the model site were screened for suitability in the constructed wetland based on the following criteria: (a) phytoremediation potential (especially metal uptake), (b) sedimentation and erosion control, (c) habitat function, (d) public deterrent potential and (e) rate of plant establishment, tolerances and maintenance requirements. Transplantation was chosen as the main vegetation establishment methodology in the constructed wetland. The species woolgrass (Scirpus cyperinus) and soft rush (Juncus effusus) were chosen to dominate the interior berms and littoral edges of the constructed wetland cells. The buffer areas were dominated by meadowsweet (Spiraea alba var. latifolia) and the open water areas were dominated by cowlily (Nuphar variegate) and pickerelweed (Pontederia cordata) species. A diverse, self-sustaining vegetative community was successfully established in the constructed wetland. The transplant success was gauged by mortality census in the spring of 2003. Over all, 138 dead transplants were observed, many of which had died as a direct result of washout. These computes to an overall site establish success rate of about 87.3%. The species, which suffered the highest mortality rates, were the pickerelweed, with approximately 50 dead plants, the meadowsweet with 32 observed dead plants and woolgrass with 27 dead plants.

Pocosins are shrub wetlands of the southeastern coastal plain maintained by fire. Increased herbaceous plant diversity has been reported after wildfire. To test the effect of radiant heating on the seed bank of pocosin-upland ecotones, wet heat treatments were applied to Sphagnum substrate from a Virginia small depression pocosin. The seedling emergence method was used to quantify wetland seedling abundance and richness. Extant vegetation was measured at each seed bank sampling area and the seed bank and vegetation were compared with Sorenson similarity values. No significant seedling abundance, richness, or evenness effects were detected among wet heat and control groups. However, the high wet heat treatment (75 °C) significantly reduced the density of Sphagnum cuspidatum capitula more than 80% relative to the control. Mean seed bank density was 6,209 seedlings/m2 (richness = 11) and was dominated by Scirpus cyperinus (97.8%), contained many early successional species. The seed bank did not cl...

Many studies have chronicled the early development of vegetation in wetlands created as mitigation for wetland impacts; however, very few studies have followed the floristics of wetlands that are more than 10 years post-creation. This article reports the results of vegetation composition and structural analysis within eleven 20-yr-old created non-tidal, emergent wetlands. Vegetation and inundation were sampled in 173 plots within 11 wetlands during the 1992 and 1994 growing seasons. A drought occurred in 1993, thus analyses characterized vegetative response and included weighted average (weighted by the tolerance of the species to excess soil moisture), species richness, species composition, and life history strategy. Weighted average and species richness increased in 7 and 10 of the 11 sites, respectively. There was little change among most species including Typha latifolia and Scirpus cyperinus, the two species with highest importance values (IV). However, among the top 10 species ranked by IV, two aquatic species decreased and a facultative species increased. Only one of the 10 most important species, Eleocharis obtusa, was an annual and only one, Salix nigra, was a woody perennial and the IV of both species declined during the study. After 20 years, a transition from annual to perennial graminoid life histories is suggested; however, succession from emergent to shrub–scrub or forested wetland is not indicated.

Plant cover, density, and standing crop biomass were measured and compared in a created wetland and an adjacent freshwater marsh (reference wetland) in Charles City County, Virginia. No significant difference was observed between monthly standing crop in the created wetland and the reference wetland. Species composition differed between sites (mean SI < 0.50) with no significant relationship between species composition and distance from adjacent seed source. Dominant species in the created wetland (Eleocharis obtusa, Juncus acuminatus) were dissimilar to those of the reference wetland (Dichanthelium dichotomum var. dichotomum, Scirpus cyperinus). Results suggest that if both standing crop and composition are going to be used to establish short-term goals for a created wetland, these two measures should not be considered interdependent. Further, the high relative importance of perennials within the created wetland does not fit primary succession predictions, indicating that certain wetland perenni...

Constructed wetlands have the potential to be used for treatment of N-rich livestock wastewater. Our objectives were to evaluate both the time effect and increasing N loading rates on soil N distribution and NH + 4 -N concentration in surface-pore water of constructed wetlands. A 5-yr study in North Carolina investigated two wetland systems that treated swine lagoon wastewater. Wetland System 1 was planted to a Schoenoplectus americanus (Pers.) Volkart ex Schinz & R. Keller, S. tabernaemontani (K.C. Gmel.) Palla, Scirpus cyperinus (L.) Kunth, and Juncus effusus L. plant community, and Wetland System 2 was planted to a Typha angustifolia L., T. latifolia L., and Sparganium americanum Nutt. plant community. Nitrogen loading rates were increased annually from 0.6 to 2.7 g m -2 d -1 . Soils were analyzed for total N annually. Surface-pore water was sampled with equilibrators and analyzed for NH + 4 -N. Although the total N accumulation significantly increased with time in both systems, total soil N accumulation by depth did not differ significantly between systems. Distribution profiles in the surface-pore water column showed that NH + 4 -N was transported upward into surface water at N loading rates from 1.2 to 2.7 g m -2 d -1 . As total N loading rates increased annually in both wetland systems, soil pore water had higher levels of NH + 4 -N but N removal efficiency of the wetlands sharply decreased. Accumulation of high levels of NH + 4 -N (>200 mg L -1 ) in soil pore water could negatively affect long-term ability of wetland systems to treat wastewater with high N levels.

Constructed wetland treatment of swine wastewater probably involves substantial denitrification. Our objective was to assess denitrification and denitrification enzyme activity (DEA) in such wetlands in relation to plant communities, N loading, carbon or nitrogen limitations, and water depth. Two wetland cells each 3.6 m wide and 33.5 m long were connected in series. One set of cells was planted with rushes and bulrushes, including soft rush (Juncus effusus L.), softstem bulrush [Schoenoplectus tabernaemontani (K.C. Gmel.) Pallal, American bulrush [Schoenoplectus americanus (Pers.) Volkart ex Schinz & R. Keller], and woolgrass bulrush [Scirpus cyperinus (L.) Kunthl. Another set was planted with bur-reeds and cattails, including American bur-reed (Sparganium americanum Nutt.), broadleaf cattail (Typha latifolia L.), and narrowleaf cattail (Typha angustifolia L.). The sets will be referred to herein as bulrush and cattail wetlands, respectively. Denitrification and DEA were measured via the acetylene inhibition method in intact soil cores and disturbed soil samples that were taken during four years (1994-1997). Although DEA in the disturbed samples was greater than denitrification in the core samples, the measurements were highly correlated (r 2 ≥ 0.82). The DEA was greater in the bulrush wetlands than the cattail wetlands, 0.516 and 0.210 mg N kg -1 soil h -1 , respectively; and it increased with the cumulative applied N. The DEA mean was equivalent to 9.55 kg N ha -1 d -1 in the bulrush wetlands. We hypothesized and confirmed that DEA was generally limited by nitrate rather than carbon. Moreover, we determined that one of the most influential factors in DEA was wetland water depth. In bulrush wetlands, the slope and r 2 values of the control treatment were -0.013 mg N kg -1 soil h -1 mm -1 depth and r 2 = 0.89, respectively. Results of this investigation indicate that DEA can be very significant in constructed wetlands used to treat swine wastewater.

Plant decomposition and litter accumulation are important components of wetland functions, yet they have rarely been evaluated in created wetlands. In this study, eleven 20-yr and six 2-yr-old depressional wetlands, the most common type of created wetlands, were investigated. We measured plant decomposition as mass loss over 507 days for both age classes and litter accumulation as litter (detritus) mass present in the 20-yr-old wetlands. The wetlands were all created via excavation and contained shallow facultative wetland and deeper obligate wetland plant communities that were often dominated by Scirpus cyperinus and Typha latifolia, respectively. In the decomposition study, stems and leaves from each species were harvested from an adjacent 20-yr-old wetland site and placed in separate plastic mesh bags. Bags were deployed in March 1994 and were recovered after 2, 161, 258, 364, and 507 days. In the litter accumulation study, plant litter that accumulated on top of alluvium was harvested in 0.25...

Metal accumulations in sediments and plants of constructed and natural wetlands were compared in two wetlands constructed by the Tennessee Valley Authority (TVA) for the treatment of acid mine drainage and a natural wetland. Load rates and removal efficiencies of most metals were generally greater in the constructed wetlands than in the natural wetland. There were similar sediment and plant metal concentrations between one constructed wetland and the natural wetland and greater metal concentrations in the sediments and plants in the other constructed wetland compared to the natural wetland. Data indicate that Mn, Zn, Cu, Ni, B, and Cr are being accumulated in the plants at all three wetlands, although accumulation of metals by these plants accounts for only a small percentage of the removal of the annual metal load supplied to each wetland.

In many locations nitrogen (N) addition to the environment is of concern because of the existing quality or intended use of groundwater. To address this concern we evaluated the impact of residence time on N removal in constructed wetlands employed to treat domestic wastewater. Constructed subsurface flow (SF) wetlands were installed at two locations for this study. Twelve small, gravel-based, SF wetlands were constructed at the Virginia Tech’s Kentland Research Farm (KRF). Treatments included combinations of two plant species [woolgrass (Scirpus cyperinus) and cattail (Typha latifolia)] and three residence times (2.6, 3.9 and 5.9 days). Twelve larger SF wetlands were constructed at the Powell River Project (PRP) site. Treatments at the PRP site consisted of the same plant species and three residence times (4, 8 and 12 days). The wastewater at both sites was septic tank effluent (STE) from a single family residence. Changes in ammonium (NH+4), nitrate (NO−3), and total Kjeldahl N (TKN) were determined by monitoring influent and effluent quality over a 3-year period. Plant species had little impact on N concentration or removal. Both NH+4 and TKN concentrations in the wetlands decreased exponentially with increased residence time. Removal of NH+4 and TKN ranged from 18.1 to 39.0% and from 31.3 to 45.8%, respectively, for the KRF site and from 44.4 to 73.4% and from 46.2 to 67.5%, respectively, at the PRP site. The NO−3 concentrations in the influent and effluent at both sites were low and no differences in concentrations with residence time was observed. Temperature dependent rate constants (KT), developed from NH+4–N and TKN data collected from the KRF site, was effective in predicting NH+4–N and TKN concentrations as a function of residence time in the wetlands at the PRP site.

Bioassays for allelochemical toxicity of aboveground Juncus effusus tissues were conducted with seeds and seedlings of Eleocharis obtusa and Scirpus cyperinus, two emergent sedge species (Cyperaceae) found sympatric with J. effusus, and with seeds and seedlings of J. effusus itself to evaluate potential autotoxicity. Bioassays were performed under controlled, axenic conditions with aqueous shoot extract treatments simulating in situ dissolved organic carbon concentrations. With respect to the two sedge species, neither shoot development nor seedling biomass accrual was significantly suppressed by lyophilized whole extracts from J. effusus. Although the extracts induced no significant reduction in growth of E. obtusa or S. cyperinus, biomass-specific chlorophyll a concentration was significantly reduced in E. obtusa seedlings. In contrast, seedlings of J. effusus exhibited significant reductions of biomass and chlorophyll a concentrations, and seedling shoot development was retarded in response to leachate exposure. Results of the present study suggest that J. effusus seedlings possess autotoxic sensitivity to extracts of dead, aboveground tissues of adult plants. Competitive effects on plant community structure can occur via indirect, exploitative competition for resources or direct interference among competing individuals, the latter usually taking the form of allelochemical interac

Activity concentrations of 137Cs in sediments, as well as extractable sediment concentrations of K, Na, Mg, Ca, Mn, Zn and P, pH, percent organic matter and cation exchange capacity, were used as independent variables in an incomplete principal component analysis to identify factors affecting 137Cs activity concentrations in 12 species of native wetland and terrestrial plants invading a recently exposed lake bed. Sediments in the lake had been contaminated 35 years previously from discharges at a nuclear production reactor. 137Cs activity concentrations in plants were positively correlated with sediment concentrations of Na and 137Cs, and inversely correlated to K and pH. Significant decreases in concentrations of sediment constituents (from 3 to 77%), as well as a 42% decline in 137Cs activity concentrations in plants, occurred during the three-year period. Significant differences in 137Cs activity concentrations among plant species, driven by low concentrations in cattails (Typha latifolia), were observed. Terrestrial species had significantly lower activity concentrations of 137Cs than species classified as wetland (arithmetic mean±S.E. of 1069±151 and 2602±394, respectively). Concentration ratios (Bq kg-1 dry plant/Bq kg-1 dry soil) were among the highest reported in the literature (arithmetic mean±S.D.=12.5±28.9; geometric mean=1.6, geometric S.D.=1.4) and were attributed to kaolinitic sediments of pH

Lythrum salicaria (purple loosestrife) is a perennial herbaceous plant that was introduced in the 1800s into North America. Its geographical expansion has generated much concern. in part because its spread may lead to a reduction in the diversity of plant species in wetlands. We tested this hypothesis by examining the association between the abundance ofLythrum salicaria and vascular plant species richness in forty-one 2m × 2m plots located along the Bar River, Ontario, Canada. No significant differences in mean species richness were found between plots with and withoutL. salicaria. For those plots containingL. salicaria, species richness was not related to the percentage cover ofL. salicaria. Furthermore, there were no significant differences in the number of introduced plant species between plots with and withoutL. salicaria, nor were there differences with increasing percent cover ofL. salicaria. Plant species such asNuphar variegatum. Scirpus atrovirens, Scirpus cyperinus, andScirpus microcarpus were more likely to be found in plots withLythrum salicaria than without. However, no plant species were significantly more likely to be found in plots withoutLythrum salicaria than with it. Collectively, these results provide no support for the hypothesis that the number of species in wetlands is decreasing in association with the invasion ofLythrum salicaria in Ontario.

Acid mine drainage (AMD) has impacted more than 3200 km (2000 miles) of streams in West Virginia. Constructed wetlands have been used for passive AMD treatment since the early 1980s, and plant growth studies in constructed wetlands are scarce. Two populations of woolgrass [Scirpus cyperinus (L.) Kunth], a bulrush species common in naturally present AMD wetlands, were investigated to determine population level differences in aboveground and belowground growth response to AMD. Differences at the level of population were found in aboveground parameters. One population had significantly greater aboveground growth than the other population during portions of the growing season when growing in AMD, suggesting greater ability to grow in AMD wetlands. Differences at the level of population were also found for root growth; however, the root growth response to AMD was not different between populations. Treatment with AMD slightly increased aboveground growth but reduced belowground growth. This suggests a potential for differential allocation to different growth components under AMD treatment. These results suggest there is a potential for selecting genotypes of woolgrass for increased performance in the presence of AMD.

Reserves of buried seeds are known to have an important role in the dynamics of plant communities. This is particularly so in wetlands, where periodic low water events are essential for plants to re-establish from seeds. In spite of the growing literature on reserves of buried seeds, little is known about this resource in beaver ponds. This study was designed to 1) document species found in beaver pond seed banks, 2) estimate their relative abundance, and 3) test whether the abundance and richness of seeds differ between young and old beaver ponds. Soil samples were collected from 14 beaver ponds in Gatineau Park (Quebec) in May 1995. Samples were spread out in plastic trays containing a sand and peat substrate and were placed in a growth chamber with fluctuating light and temperature regimes to stimulate germination. More than 2000 seedlings representing 42 species germinated from the various soil samples, yielding an estimated density of 2300 seedlings/m2.Juncus effusus (426 seeds/m2),Leersia oryzoides (390 seeds/m2),Scirpus cyperinus (246 seeds/m2),Juncus brevicaudatus (170 seeds/m2), andLudwiga palustris (98 seeds/m2) were the 5 most abundant species. The abundance and richness of germinating seeds did not differ significantly between young and old beaver ponds.

The impact of acid vine drainage on the decomposition of wetland plant species of northern West Virginia was studied to determine if the potential exists for nutrient cycling to be altered in systems used to treat this drainage. There were two objectives of this study. First, decomposition of aboveground plant material was measured to determine species decomposition patterns as a function of pH. Second, decomposition of litter from various pH environments was compared to assess whether litter origin affects decomposition rates. Species differences were detected throughout the study. Decomposition rates of woolgrass [Scirpus cyperinus (L.) Kunth] and common rush (Juncus effusus L.) were significantly lower than those of calannus (Acorus calamus L.) and rice cutgrass (Leersis oryzoides L.). Differences among species explained a large proportion of the variation in percentage of biomass remaining. Thus, differences in litter quality among species was important in determining the rate of decomposition. In general, significantly more decomposition occurred for all species in high pH environments, indicating impeded decomposition at low pH. While decomposition of some species after differed depending on its origin, other species showed no effect. Cattail (Typha latifolia L.), in particular, was found to have lower decomposition rates occurring with material grown at low pH. Lower decomposition rates could result in lower nutrient availability leading to further reduction of productivity under low pH conditions

The study investigated vegetative and soil properties in four created mitigation wetlands, ranging in age from three to ten years, all created in the Virginia Piedmont. Vegetation attributes included percent cover, richness (S), diversity (H'), floristic quality assessment index (FQAI), prevalence index (PI), and productivity [i.e., peak above-ground biomass (AGB) and below-ground biomass]. Soil attributes included soil organic matter (SOM), gravimetric soil moisture (GSM), pH, and bulk density (D(b)) for the top 10 cm. Species dominance (e.g., Juncus effusus, Scirpus cyperinus, Arthraxon hispidus) led to a lack of differences in vegetative attributes between sites. However, site-based differences were found for GSM, pH, and SOM (P 0.001). Soil attributes were analyzed using Euclidean cluster analysis, resulting in four soil condition (SC) categories where plots were grouped based on common attribute levels (i.e., SC1 SC2 SC3 SC4, trended more to less developed). When vegetation attributes were compared between SC groups, greater SOM, lower D(b), more circumneutral pH, and higher GSM, all indicative of maturation, were associated with higher H' (P 0.05), FQAI (P 0.05), and total and volunteer percent cover (P 0.05), and lower AGB (P 0.001), PI (P 0.05), and seeded percent cover (P 0.05). The outcome of the study shows that site age does not necessarily equate with site development with soil and vegetation developmental rates varying both within and among sites. The inclusion of soil attributes in post-construction monitoring should be required to enhance our understanding and prediction of developmental trajectory of created mitigation wetlands.

As the use of constructed stormwater wetlands to treat stormwater runoff becomes more frequent, strategies for maintaining their pollutant removal over time must be examined. One potential strategy is plant harvesting to remove nutrients that would otherwise be deposited back into the wetland during senescence. Vegetation was harvested in two stormwater wetlands located in Smithfield and Pactolus, North Carolina, in 2007 to evaluate the ability of five wetland plant species to uptake nitrogen. Biomass samples from harvested emergent vegetation for Pontederia cordata (Pickerelweed), Saururus cernuus (Lizard Tail), Scirpus cyperinus (Wool Grass), Sagittaria latifolia (Arrowhead) and Schoenoplectus tabernaemontani (Softstem Bulrush) were collected in October 2007 and analyzed for nutrient content. At the Pactolus wetland Pontederia cordata, Scirpus cyperinus and Schoenoplectus tabernaemontani biomass retained significantly (p

Eriophorum cyperinum Linnaeus, Species Plantarum, ed. 2, 1: 77. 1762. "Habitat in America septentrionali." RCN: 442. Lectotype (Reveal & al. in Huntia 7: 219. 1987): Clayton 205 (BM-000051167). Current name: Scirpus cyperinus (L.) Kunth (Cyperaceae)., Published as part of Jarvis, Charlie, 2007, Chapter 7: Linnaean Plant Names and their Types (part E), pp. 490-515 in Order out of Chaos. Linnaean Plant Types and their Types, London :Linnaean Society of London in association with the Natural History Museum on page 504, DOI: 10.5281/zenodo.291971

Animal waste management is a national concern that demands effective and affordable methods of treatment. We investigated constructed wetlands from 1993 through 1997 at a swine production facility in North Carolina for their effectiveness in treatment of swine wastewater from an anaerobic lagoon. We used four wetland cells (3.6 U 33.5 m) with two cells connected in series. The cells were constructed by removing topsoil, sealing cell bottoms with 0.30 m of compacted clay, and covering with 0.25 m of loamy sand topsoil. One set of cells was planted with bulrushes (Scirpus americanus, Scirpus cyperinus, and Scirpus validus) and rush (Juncus effusus). The other set of cells was planted with bur–reed (Sparganium americanum)and cattails (Typha angustifolia and Typha latifolia). Wastewater flow and concentrations were measured at the inlet of the first and second cells and at the exit of the second cell for both the bulrush and cattail wetlands. Nitrogen was effectively removed at mean monthly loading rates of 3 to 40 kg N ha –1 day –1 ; removals were generally >75% when loadings were

Growth and biomass accumulation of selected nutrients and trace metals were monitored for six species of aquatic macrophytes during June, August and November, 1993. Plant species were cultivated in two polyculture treatments, each replicated three times. Polyculture I consisted of Scirpus acutus (hardstem bullrush), Phragmites communes (common reed), and Phalaris arundinacea (canary grass). Polyculture H consisted of Typha spp. (cattail), Scirpus atrovirens (green bullrush), and Scirpus cyperinus (wool grass). Each of the six cells (6 x 9 x 0.6 m), was operated as a gravel-substrate, subsurface-flow wetlands in a continuous recirculating mode. At six week intervals, macro, micro and trace elements were dissolved and added to the sump of the recirculating system. On each of three sampling dates, replicate shoot and root samples were collected, segregated by species and tissue type (roots, rhizomes, stems and leaves), and prepared for gravimetric biomass estimates and chemical analysis. Tissue specific concentrations of N, P, K, Ca, Mg, Fe, Mn, Zn and Cu, were determined on each date for each species and tissue type. Results will be discussed with respect to species specific growth rates, biomass accumulation, and seasonal uptake and translocation of plant nutrients.

From June 1993 through February 1994, the removal of NH4-N was evaluated in constructed wetlands at the TVA constructed wetland research facility in Muscle Shoals, AL. The objectives were to determine rates for NH4-N removal and speculate on potential mechanisms for removal. Nine constructed wetland cells were used with approximate dimensions of 9.1 × 6.1 × 0.6 m3 and a recirculating subsurface flow system in a gravel base. Treatments consisted of an unplanted (WO=control) and two polycultural planting schemes (P1=Scirpus acutus, Phragmites communis and Phalaris arundinacea; P2=Typha sp., Scirpus atrovirens georgianus and Scirpus cyperinus) replicated 3 times. Salt solutions were added and recirculated in each cell resulting in initial concentrations of 50 and 300 mg l−1 of NH4-N and COD, respectively, when fully diluted with wetland water. Salts were added to wetlands approximately every 6 weeks with the first addition on June 1, 1993 and the last addition on February 9, 1994 for a total of 6 time periods (times I, II, III, IV, V and VI). The COD of the waters was removed at rates ranging from 5.5 to 10 g/m2/d during times I through IV with no discernible difference amongst the planting treatments. Wetland cells with P1 were more efficient at removing NH4-N (1.1 g/m2/d) than P2 (0.6 g/m2/d) or WO (0.5 g/m2/d) at time I with differences decreasing by time IV (0.3 to 0.7 g/m2/d). During the winter (times V and VI), there were no differences in NH4-N removal amongst planting treatments with an average removal rate of 0.35 g/m2/d. There was a seasonal change in NH4-N removal in all the treatments, with the change most noticeable in the planted cells. The removal of NH4-N in WO was speculated to be due to a combination of sorption onto gravel, microbial assimilation, and nitrification at the air-water interface. The extra NH4-N removal in the planted cells diminished in the winter because the removal was most likely due to a combination of enhanced nitrification from O2 transport and NH4-N uptake mediated by seasonal macrophyte growth.

A continuous-belt herbicide wiper was developed to apply herbicides to weeds that are taller than cranberry (Vaccinium macrocarponAit.) plants. An endless belt with a sponge attached to the entire length of the belt moves through a reservoir containing a herbicide solution. A variable pressure wheel squeezes the excess liquid out of the sponge and returns it to the reservoir. The herbicide is deposited on the leaves of the weeds as the belt moves in a horizontal plane, perpendicular to the forward movement of the wiper. Control of Walter's sedge (Carex walterianaBailey), woolgrass [Scirpus cyperinus(L.) Kunth] and switchgrass (Panicum virgatumL.) was obtained when glyphosate [N-(phosphonomethyl)glycine], dalapon (2,2-dichloropropionic acid), and paraquat (1, 1′-dimethyl-4,4′-bipyridinium ion) were applied using the continuous-belt wiper. No injury to cranberry plants was observed.

Mineral element concentrations were measured in the component parts of different species of plants from a floodplain community along a coastal plain stream in South Carolina, USA. Frequency distributions of concentrations of mineral elements were positively skewed, although dis- tributions of P. K, Ca and B concentrations tended to be less skewed than those of some trace elements (Na, Al, Cs- 137). Sources of variation in the elemental compositions of the major natural plant species of the floodplain were examined statistically. In herbaceous species (Scirpus cyperinus and Andropogon sp.), 52-56% of the variation in P, Mg, Mo and Na concentrations was accounted for by differences in the chemical composition of stems, leaves, roots and seeds. Seasonal variation in the mineral element composition of leaves from woody species was greater than that in stems. Concentra- tions of K, P. Al, Mo and Sr in leaves were significantly different among seasons in 3 woody species (Alnus serrulata, Myrica cerifera, Salix nigra). Mean concentrations of Ca, Na, Al, B, Mo and Sr in leaves tended to increase from spring to autumn, while K, Mg, N, P. Cu, Zn and Cs-137 concentrations declined. For macroelements (P, Mg, K, Ca and N) and some trace elements (B, Sr, Na and Mo), >50% of the variation in concentrations was accounted for by differences among 4 species (Polygonum punctatum, Scirpus cyperinus, Salix nigra, Sagittaria latifolia) while

A woolgrass (Scirpus cyperinus (L.) Kunth) community in Juneau County, Wisconsin was studied by means of belt transects in August, 1951. Species composition and cover values for a total of 35 stand samples were recorded. Units based on a field technique of recording data by samples of physiognomic homogeneity revealed a very definite structure. These types were distinguished: woolgrass-grass, woolgrass-spikerush, and woolgrass-sedge. Analysis showed these types to be related to water depths and allowed development of a hypothesis of the successional trends of these units. The dominance of woolgrass in a community similar in almost all respects to cattail communities was probably due to the pattern of water level fluctuation. The results of this study indicate a close ecologic relationship between cattail and woolgrass.

Rising atmospheric CO(2) levels alter the physiology of many plant species, but little is known of changes to root dynamics that may impact soil microbial mediation of greenhouse gas emissions from wetlands. We grew co-occurring wetland plant species that included an invasive reed canary grass (Phalaris arundinacea L.) and a native woolgrass (Scirpus cyperinus L.) in a controlled greenhouse facility under ambient (380 ppm) and elevated atmospheric CO(2) (700 ppm). We hypothesized that elevated atmospheric CO(2) would increase the abundance of both archaeal methanogen and bacterial methanotroph populations through stimulation of plant root and shoot biomass. We found that methane levels emitted from S. cyperinus shoots increased 1.5-fold under elevated CO(2), while no changes in methane levels were detected from P. arundincea. The increase in methane emissions was not explained by enhanced root or shoot growth of S. cyperinus. Principal components analysis of the total phospholipid fatty acid (PLFA) recovered from microbial cell membranes revealed that elevated CO(2) levels shifted the composition of the microbial community under S. cyperinus, while no changes were detected under P. arundinacea. More detailed analysis of microbial abundance showed no impact of elevated CO(2) on a fatty acid indicative of methanotrophic bacteria (18:2ω6c), and no changes were detected in the terminal restriction fragment length polymorphism (T-RFLP) relative abundance profiles of acetate-utilizing archaeal methanogens. Plant carbon depleted in (13)C was traced into the PLFAs of soil microorganisms as a measure of the plant contribution to microbial PLFA. The relative contribution of plant-derived carbon to PLFA carbon was larger in S. cyperinus compared with P. arundinacea in four PLFAs (i14:0, i15:0, a15:0, and 18:1ω9t). The δ(13)C isotopic values indicate that the contribution of plant-derived carbon to microbial lipids could differ in rhizospheres of CO(2)-responsive plant species, such as S. cyperinus in this study. The results from this study show that the CO(2)-methane link found in S. cyperinus can occur without a corresponding change in methanogen and methanotroph relative abundances, but PLFA analysis indicated shifts in the community profile of bacteria and fungi that were unique to rhizospheres under elevated CO(2).

Five species of grass, one sedge, and cattail were grown on a peat-sand filter bed irrigated with sewage effluent. Yields, uptake of nitrogen and phosphorus, and lodging problems were determined for all species when grown to various heights ranging from 5 to 75 cm.