Wetland Ponds Research Articles

The effect of Sesuvium portulacastrum for reducing inorganic nitrogen pollution in coastal mariculture wetland

Mariculture ponds are essential components of the coastal wetland, which are often criticized by eutrophication risk for the dissolved inorganic nitrogen (DIN) input to the coastal zone by the culture tailwater. However, the reduce of this DIN pollution was difficult because the tailwater is hard to collect and the treatment is inefficient and expensive. Sesuvium Portulacastrum is a coastal vegetation which has high efficiency in DIN absorption from the seawater and sediment. In this study, we use Sesuvium Portulacastrum as a tool species to study the control behavior of the DIN in mariculture ponds wetland. The change trend of DIN in pond water and benthic species in pond sediment was investigated. The results showed that Sesuvium Portulacastrum reduced NH4+, NO3-, and NO2- in the pond water by 83.21%, 95.22%, and 91.32%, respectively. The species number of benthic organisms was enhanced from 2 to 5 and the species structure was more optimized in Sesuvium Portulacastrum pond than control pond. At the end of the experiment, eutrophication indicator species (Capitella capitata) was disappeared in the Sesuvium Portulacastrum pond. Those suggest that the coastal vegetation (Sesuvium Portulacastrum) have great potential to eliminate DIN pollutants in mariculture pond wetland.

Dynamic interplay of soil parameters and CO2 sequestration in Solanku-runi Freshwater Pond Wetland, Tamil Nadu, India

This study investigates the dynamic interplay between soil temperature, pH levels, and CO2 sequestration across ten sample sites over a four-month periods from January to April 2018 in Solankuruni freshwater pond wetland in Madurai District, Tamil Nadu, India. The soil temperature fluctuations, ranging from 31°C to 44°C, reveal distinct site-specific patterns, with sample site six consistently exhibiting the highest temperatures. Soil temperature exhibited notable variations, influenced by factors such as soil composition, and microclimate variations. Regarding pH level, the range between 6.23 to 8.1 display variability influenced by factors like soil composition and anthropogenic influences, study site five consistently leading in pH levels. Soil CO2 sequestration varying from 1517.857 g/m² to 3357.143 g/m², highlight the influence of soil microbial activity, vegetation cover, and soil moisture content, ninth site consistently showing the highest sequestration rates. The findings reveal substantial variations in factors such as soil composition, vegetation type, microclimate, and anthropogenic activities, prominence the intricate nature of soil dynamics. These results stress the importance of understanding the interconnections among soil properties to create effective climate change mitigation strategies. Moreover, the research provides valuable understanding of the intricate connections between soil properties, emphasizing the necessity for region-specific studies to inform comprehensive environmental policies. Understanding these dynamic soil processes is crucial for advancing sustainable land management practices and boosting soil carbon sequestration in wetland ecosystems.

Responses of Vallisneria natans and Pistia stratiotes to Cu2+ and Mn2+ stress: Occurrence of caffeic acid and its degradation kinetics during chlorination

Macrophytes are crucial in maintaining the equilibrium of aquatic ecosystems. However, the pattern of macrophyte-derived caffeic acid (CA) release under heavy metal stress is yet to be fully understood. More importantly, due to its functional groups, CA may be a precursor to the formation of disinfection by-products, posing threats to water ecology and even safety of human drinking water. This study analyzed the responses of CA released by Vallisneria natans (V. natans) and Pistia stratiotes (P. Stratiotes) when exposed to Cu2+ and Mn2+ stress. Additionally, the CA levels in two constructed wetland ponds were detected and the degradation kinetics of CA during chlorination were investigated. Results indicated that CA occurred in two constructed wetland ponds with the concentrations of 44.727 μg/L (planted with V. natans) and 61.607 μg/L (planted with P. Stratiotes). Notably, heavy metal stress could significantly affect CA release from V. natans and P. Stratiotes. In general, under Cu2+ stress, V. natans secreted far more CA than under Mn2+ stress, the level could reach up to 435.303 μg/L. However, compared to V. natans, P. Stratiotes was less affected by Cu2+ and Mn2+ stress, releasing a maximum CA content of 55.582 μg/L under 5 mg/L Mn2+ stress. Aquatic macrophytes secreted more CA in response to heavy metal stresses and protected macrophytes from harmful heavy metals. CA degradation followed the pseudo first-order kinetics model, and the chlorination of CA conformed to a second-order reaction. The reaction rate significantly accelerated as NaClO, pH, temperature and Br- concentration increased. A new pathway for CA degradation and a new DBP 2, 2, 3, 3-tetrachloropropanal were observed. These findings pointed at a new direction into the adverse effect of CA, potentially paving the way for new strategies to solve drinking water safety problems.

Soil carbon dynamics in drained prairie pothole wetlands

Drainage leads to trade-offs between crop production efficiency and wetland conservation, with complex impacts on ecosystem services. In North America’s Prairie Pothole Region, wetland drainage is widespread, often to increase the available land for cultivation, prevent crop loss due to flooding, and manage soil salinity. Wetlands are known for providing key ecosystem services such as improved water quality, flood mitigation, and carbon storage. There is limited research on how changes to soil hydrology and soil redistribution through wetland drainage can impact soil carbon storage and persistence in this region. This research evaluates factors that contribute to soil carbon storage in drained prairie pothole wetland based on 33 drained wetlands in Saskatchewan, Canada. These analyses showed regional differences in the response of soil carbon storage to drainage that are driven by environmental factors such as annual precipitation, temperature, and wetland permanence. We observed increasing soil carbon storage from the Dark Brown to Black soil zones, as well as with longer wetland pond permanence. The sampling depth used for calculating soil carbon storage was especially important when comparing geographically across the soil zones as the Black soil zone had greater soil carbon stored at depth. Soil carbon was also intensively monitored over 2 years following installation of surface drainage across a wetland complex (8 drained wetlands) where water was partially directed to a consolidation wetland. We further assessed changes in soil carbon dynamics and protection from microbial decomposition based on three soil organic matter fractions, ATR-FTIR for organic matter functional groups, and phospholipid fatty acid analysis to understand the microbial community abundance and structure. After 2 years following drainage, ephemeral wetlands with short pond permanence were found to be most sensitive to drainage and the only wetland class with decreases in soil carbon. The temporary and seasonal wetland classes showed no significant differences in soil carbon content but there were changes in the organic matter with depth due to soil redistribution during drainage implementation. Jointly, this research provides region-specific estimates of soil carbon storage in drained prairie pothole wetlands that can be used to inform wetland soil carbon management in cultivated fields.

Pre‐loved home: Egg clutches of the striped marsh frog, Limnodynastes peronii, detected in water‐filled burrows created by the hunter hairy crayfish, Cherax setosus

AbstractMany animals create their own microhabitats that are not naturally present in the environment, such as nests and burrows, which are extended phenotypes that perform tasks related to survival and reproduction. Animals may be able to avoid the costs of implementing their own extended phenotypes by exploiting those already created by other species, including structures that are not actively in use or abandoned. Herein, we report on the striped marsh frog, Limnodynastes peronii, from Australia utilizing crayfish burrows for depositing their egg clutches. Field observations revealed large numbers of recently hatched L. peronii tadpoles in two flooded burrows likely created by the hunter hairy crayfish, Cherax setosus, near an ephemeral wetland pond on Kooragang Island, Australia that had partially dried. Our observations indicate that L. peronii may opportunistically exploit crayfish burrows which, when flooded, become suitable aquatic sites for breeding. These small waterbodies may provide fitness benefits to offspring, reducing exposure to aquatic predators found in naturally occurring aquatic systems but at the expense of increasing competition and cannibalism among confined siblings. These burrows may provide suitable microhabitat refuge during droughts, and breeding habitat for amphibians when other typical breeding habitats may not exist due to wetland drying. This is an example of an amphibian using an extended phenotype of a crustacean for the purposes of reproduction, revealing a unique interaction between these species that has not been reported.

Hydrogeomorphic controls on the thermal regime of natural and restored wetlands in a glacial plain

Wetland thermal regimes are underexplored but essential attributes of habitats and function for regulatory and action agencies to evaluate the success of nationwide restoration activities. Here we investigate regional and local controls on the hydrological and thermal regimes of small natural and restored wetlands in the St. Lawrence River Valley region of northern New York State, USA. We deployed pressure and temperature sensors in seventeen wetland ponds and adjacent groundwater piezometers to obtain hourly measurements of stage and water temperature for one year. For this humid continental climate, we observed seasonal hysteresis in air and water temperature, which extended to benthic and groundwater environments. We found the temporal behavior of wetland temperatures within this region were strongly similar across sites, suggesting two seasonal controls: regional atmospheric forcing as a primary control and local groundwater offset induced by hydrogeomorphic settings as a secondary control. In particular, wetland temperatures showed the greatest spatial variability with a consistent rank order among sites during summer (standard deviation ranging 0.9–2.8℃). Three regional hydrogeomorphic settings corresponded to varying thermal behaviors in dry summer due to different degrees of groundwater sourcing. Results demonstrate that the imprints of hydrogeomorphic controls on wetland thermal regimes are best assessed in both summer and winter, due to differences in groundwater availability of wetland thermal regimes.

Mercury transport and methylmercury production in the lower Cedar River (Iowa) floodplain

Scant attention has been paid to cycling of total mercury (THg) and methylmercury (MeHg) in agriculturally intensive watersheds. Monitoring of Hg and MeHg in river basins provides valuable information on the efficacy of environmental policy and the impacts of land use and climate change on Hg fluxes and biogeochemistry. We report on Hg and MeHg yields in the Cedar River (Iowa), a major tributary of the Upper Mississippi River, and on Hg biogeochemistry in a floodplain of the lower Cedar River, with emphasis on Hg cycling in groundwater and wetland ponds. For the period 2016 to 2018, total Hg yields for the 21,000 km2 Cedar River watershed ranged from 2.6 to 6.9 μg m−2 yr−1, or 25% to 70% of estimated wet deposition, and MeHg yields ranged from 0.09 to 0.18 μg m−2 yr−1. High watershed transfer efficiencies for THg are driven by soil erosion and suspended sediment delivery. Policies and land management practices targeting soil conservation are thus likely to have significant impacts on downstream transport of Hg. Within alluvial groundwaters, Hg and MeHg concentrations were highly spatiotemporally variable, ranging from 0.5 to 2.0 ng/L for THg and 0.03–1.50 ng/L for MeHg. Microtopography exerted strong control on groundwater geochemistry and Hg biogeochemical cycling, with groundwater sampled from lower lying swales exhibiting less dissolved oxygen (DO), higher conductivity, higher dissolved organic carbon (DOC), and higher THg and MeHg. The alluvial aquifer exhibits high hydrologic connectivity with the river and groundwater THg and MeHg concentrations responded rapidly to hydrologic events, with MeHg concentrations increasing with a rising water table. Concentrations of THg and MeHg in wetland ponds were elevated compared to groundwater and most strongly correlated with DOC and UV-absorbance. Methylation potentials in pond sediments were among the highest reported for freshwater sediments, up to 0.15 d−1, which we hypothesize to be linked to high primary productivity associated with nutrient enrichment. Floodplain groundwaters and wetlands constitute important ecosystem control points for downstream MeHg delivery, the magnitude of which is sensitive to changing hydroclimate, especially flood frequency.

The ecology of coastal wetland ponds created by diamond mining in southern Namibia. 3. Fish

Diamond mining in southern Namibia creates seawalls that hold the ocean at bay, yet seawater overwashes or seeps through to fill landward excavated areas, forming numerous coastal ponds that reach 380 000 m2. These ponds span ages of 1–40 years, with the oldest ponds lying in the north, and the younger ponds in the central and southern areas. We investigated occupation of these mining ponds by marine fishes. The ponds offer sheltered, warm, nutrient-enriched environments, but become hypersaline after 10–12 years. The ponds contained predominantly west coast steenbras Lithognathus aureti and southern mullet Chelon richardsonii, with smaller numbers of seven other fish species, and all nine species being marine. The ichthyofauna was thus depauperate, but similar to that of periodically closed estuaries in the region. The size composition and gonadal development of both predominant species suggest they may breed in at least the younger ponds. However, in older, hypersaline, northern ponds, L. aureti transitions into an entirely female population via protandry, precluding breeding there. Body condition was low for both species in the northern ponds, and gut fullness greatest in the southern ponds. Growth of both species was faster in the ponds than in the sea, but after initially fast growth, L. aureti reached a plateau, suggesting stunting thereafter. Chelon richardsonii attained larger sizes in the ponds than in the ocean. For 10–12 years before hypersalinity sets in, the ponds constitute suitable habitat for fish. They are not estuaries as they have minimal freshwater input, but they do create conditions corresponding to closed estuaries that are otherwise scarce along this arid coastline. However, for a nursery function to be realised, the marine fish must return to the sea or else the ponds become an ‘ecological trap’.

Contrasting two urban wetland parks created for improving habitat and downstream water quality

This paper describes the ecology and management of two flow-through created wetlands that, in turn, defined 30 years of research by Bill Mitsch, 20 years in Columbus, Ohio (1992–2012) and 10 years in Naples, Florida (2012−2022). The Olentangy River Wetland Research Park was built in several stages from 1993 through 2010. The first stage was the creation of dual 1-ha kidney-shaped wetlands primarily fed by pumped Olentangy River water. A pattern of inflow that depended on river stage was maintained for 17 years. The two experimental wetlands were established by planting one of the wetlands with a variety of wetland macrophytes and leaving the second wetland unplanted to ultimately determine whether human introduction of wetland plants matter in the long run. In addition to maintaining data collection for hydrology, water quality, and other functions, these wetlands and several others constructed on the 20-ha floodplain site were heavily used as was the mesocosm compound, mostly for short-term (2 to 3 year) experiments by graduate students.Another 20-ha created wetland complex, called Freedom Park Wetlands, was constructed in 2007–2008 in Naples, Florida, at an abandoned citrus grove, to seasonally treat urban stormwater runoff. During that wet season, the design calls for an average water detention time of 18 days. The wetland system included a 1.9-ha deepwater pond for temporary storage of the urban stormwater pulses from what is mostly an urban watershed, followed by 2.7 ha of shallower vegetated wetland ponds designed to sequentially improve water quality. Within each wetland, there are three deep-water cells and two shallow-water cells. The water eventually exits the treatment wetlands via a rectangular and travels diffusely through a restored bottomland forest to the Gordon River and ultimately toward Naples Bay and the Gulf of Mexico. During our tenure at Florida Gulf Coast University's (FGCU) Everglades Wetland Research Park, Freedom Park was a venue with active mesocosm experiments in a constructed mesocosm compound. Several of these mesocosm experiments were the subjects of master's theses from FGCU and doctoral dissertations from our partner, University of South Florida. Our students also contributed to the local environmental communities by giving tours of the Freedom Park wetlands and our mesocosm research.

Environmental drivers of spatial and temporal water quality variability in four coastal wetlands of Lake Ontario

Great Lakes coastal wetlands serve as mediation zones between the land and the lake, regulating the fate of materials received from tributaries prior to discharge to the lake nearshore zone. To improve our understanding of water quality processing and nutrient fate in coastal wetlands, we evaluated within- and across-wetland water quality as a function of environmental drivers over a decade (2009–2018) in three drowned river mouth (Carruthers, Duffin’s, and Rouge) and one barrier lagoon (Frenchman’s Bay) wetlands on the north shore of Lake Ontario. Overall, land-use had a weak relative association with most water quality parameters, reflecting no appreciable changes in land-use across the study years. The barrier lagoon wetland Frenchman’s Bay had a distinctly different water quality pattern from the drowned river mouth wetlands, where water quality followed a high to low concentration gradient from near the tributary confluences (high) to the lake-wetland confluence (low) (permutational analysis of variance p-value < 0.001). Notably, we observed significant differences among celled (i.e., natural ponds in wetlands) and non-celled sites in Duffin’s and Rouge marshes, primarily attributed to strong covariation among phosphorus, phosphate, and organic nitrogen concentrations (permutational analysis of variance p-value < 0.001). This water-quality signature seemed to be driven by solar radiation and lake level variability (i.e., seiche inundation), inferring that wetlands may be important sites for the mobilization of legacy phosphorus in sediments under certain climatic conditions, and following seiche events.

Differential Controls of Greenhouse Gas (CO2, CH4, and N2O) Concentrations in Natural and Constructed Agricultural Waterbodies on the Northern Great Plains

AbstractInland waters are hotspots of greenhouse gas (GHG) cycling, with small water bodies particularly active in the production and consumption of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). However, wetland ponds are being replaced rapidly by small constructed reservoirs in agricultural regions, yet it is unclear whether these two water body types exhibit similar physical, chemical, and environmental controls of GHG content and fluxes. Here, we compared the content and regulatory mechanisms of all three major GHGs in 20 pairs of natural wetland ponds and constructed reservoirs in Canada's largest agricultural region. Carbon dioxide content was associated primarily with metabolic indicators in both water body types; however, primary production was paramount in reservoirs, and heterotrophic metabolism a stronger correlate in wetland ponds. Methane concentrations were correlated positively with eutrophication of the reservoirs alone, while competitive inhibition by sulfur‐reducing bacteria may have limited CH4 in both waterbody types. Contrary to expectations, N2O was undersaturated in both water body types, with wetlands being a significantly stronger and more widespread N2O sink. Varying regulatory processes are attributed to differences in age, depth, morphology, and water‐column circulation between water body types. These results suggest that natural and constructed water bodies should be modeled separately in regional GHG budgets.

Effective removal of chromium from contaminated water using horizontal subsurface flow constructed wetland with Napier grass (Pennisetum purpureum)

This study aims to explore the potential of using Napier grass (Pennisetum purpureum) as a low-cost alternative for treating wastewater contaminated with chromium (Cr) in the tannery industry. Traditional chemical treatment processes are costly, leading to many industries not committing to treatment. Phytoremediation, the use of plants to remove contaminants from the environment, could be a viable solution. The study conducted an experiment to test the tolerance and effectiveness of P. purpureum in treating wastewater containing Cr(VI) at concentrations of 20 ppm, 40 ppm, and tannery wastewater. The plant was grown in a constructed wetland pond using a batch system for 31 days. The results indicate that P. purpureum can survive and grow well in all treatments, showing tolerance to Cr. The plant's phytoremediation capacity was effective at 20 ppm of Cr(VI) as demonstrated by the chemical and physical characteristics of the medium (BOD, COD, pH, and TDS). The plant was able to remove a significant amount of total Cr and Cr(VI), with removal capacity ranging from 71.79% to 99.96%. The translocation factor (TF) for Cr in the roots was less than one, indicating that the plant has the potential to be used as a phytoremediator for Cr by accumulating it in its roots.

Wet–dry cycles influence methylmercury concentrations in water in seasonal prairie wetland ponds

Methylmercury concentrations [MeHg] in whole water were measured in 28 prairie wetland ponds in central Saskatchewan between 2006 and 2012. Ponds fell into four land use categories (established grass, recent grass, traditional cultivated, and certified organic cultivated) and two water level patterns (“Mainly Wet” ponds stayed wet at least until October and “Mainly Dry” ponds dried up each summer). Despite similar atmospheric Hg deposition, average [MeHg] and proportion of total Hg that was MeHg (%MeHg) were higher in water from ponds surrounded with established grass or organic farming; this trend may be driven by high [MeHg] at one Organic site. A stronger relationship was observed with water level patterns. Average [MeHg] and %MeHg were significantly higher in Mainly Wet ponds compared to Mainly Dry ponds. Higher [MeHg] in Mainly Wet ponds were correlated with much higher dissolved organic carbon (DOC) and sulfate (SO4−2) concentrations and higher specific UV absorbance of DOC. We suggest that prairie wetland ponds may not fit the accepted paradigm that wetlands with high [SO4−2] show inhibition of Hg methylation. Our work suggests controls such as the chemical nature of DOC or redox fluctuations in hydrologically dynamic systems may be important in determining net [MeHg] in these sites.

Coastal wetland area change for two freshwater diversions in the Mississippi River Delta

Coastal systems around the globe are being re-integrated with adjacent river systems to restore the natural hydrologic connection to riparian wetlands. The Mississippi River sediment diversions or river reconnections are one such tool to combat high rates of wetland loss in coastal Louisiana, USA by providing freshwater, sediment, and nutrients. There has been some disagreement in the published literature whether re-establishing river reconnection is slowing or contributing to coastal wetland loss. This issue is due to the difficulties in the application of remote sensing in low-relief environments where water level changes could indicate either land loss or simply temporary submergence. We analyzed land change at the receiving areas of two existing freshwater river diversions, Davis Pond and Caernarvon, which have been intermittently receiving river water for up to 2+ decades. This study provides a robust analysis of wetland land change rates in proximity these river diversions including years before river reconnection. Our analyses indicate a net land gain since river reconnection operations began at Davis Pond Diversion (+3.42 km2; range: +2.02–4.81 km2) and no statistically significant change at the Caernarvon Diversion. The Davis Pond wetland results are corroborated with data from a decadal field study documenting increased inorganic sedimentation in the soil. It is clear from this study and others, that river reconnection can increase or, in the case of Caernarvon, have no statistical effect on the land change in these systems due to differences in vegetation, hydroperiod, sediment delivery and external factors including hurricane impacts. Our remote sensing analysis was compared with a global water area change analysis mapping tool which also supported our findings.

Wetland system for geothermal wastewater management

The SFS-Wetland model used is the wastewater treatment tank belonging to Pertamina Geothermal Lahendong. Based on the slope of the existing land, it is possible to design twin gravity wetlands of a certain size. This study aimed to develop a Surface Flow System Constructed Wetland design model using Monocaria vaginalis, Salvania molesta and Colocasia esculenta, analyze stakeholder perceptions of the SFS-Wetland Model, and refine this model based on stakeholder perceptions. Stakeholders' perception of the SFS-Wetland model based on a priority scale is that the geothermal waste management system is acceptable and accountable from an environmental perspective, waste management is socially and culturally acceptable, accountable and economically feasible. The components of the SFS-Wetland Model that must be improved are land availability, utilization of other local plant potentials, final geothermal wastewater temperature ranging from 33-35oC, ease of operation/maintenance, and low and environmentally friendly operational costs. The SFS-Wetland model suggested by stakeholders to improve is the existing SFS-Wetland model by taking into account the stakeholders' perceptions of the components that must be improved, namely the expansion of land for wetland ponds as much as 2x8 = 16 pool plots with a size of 35x60m = 33600 M2.

Photosensitizing properties of dissolved organic carbon in Canadian prairie pothole wetland ponds change in response to sunlight

Dissolved organic carbon (DOC) is an important component of the global carbon cycle providing ecological services such as carbon sources for microorganisms and the provision of a protective barrier between ultraviolet radiation and aquatic organisms. Our study examined the impacts of photodegradation on the optical properties of DOC in prairie wetland ponds in central Saskatchewan, Canada. Surface water was collected from two ponds with seasonal average DOC concentrations of 71.1 mg L−1 (More-DOC Pond) and 32.7 mg L−1 (Less-DOC Pond) and filtered through 1.2 µm GF/Fs into Teflon bottles transparent to UV light. Samples divided into dark and light treatments were incubated in situ at three different depths (surface, 0.25m, and 0.5 m) and collected every 2 weeks for 4 months. Excitation emission matrix scans from 300 to 800 nm and absorbance at 254 nm were measured. Absorbance at 254 nm in the More-DOC Pond and Less-DOC Pond waters decreased by 34% and 50%, respectively. Two fluorescence components were identified corresponding to previous published peaks C and M. Although bulk DOC concentrations did not show significant differences over time, fluorescence intensity of peak C decreased by 39% and 47%, and of peak M increased by 19% and 29%, in the More-DOC Pond and Less-DOC Pond, respectively. Increases in other fluorescence indicators such as fluorescence index (35% and 22%) and FRESH (29% and 30%) were also observed. Overall, terrestrial DOC from our sampling ponds became less aromatic, more aliphatic, of lower molecular weight, and lost absorptivity and fluorescence intensity after 12 weeks of incubation. Results of this study will provide a better understanding of optical characterizations and sources of DOC, and act as a foundation to further study on the role of DOC in prairie wetland ponds.

Prairie wetlands as sources or sinks of nitrous oxide: Effects of land use and hydrology

National and global greenhouse gas (GHG) budgets are continually being refined as data become available. Primary sources of the potent GHG nitrous oxide (N2O) include agricultural soil management and burning of fossil fuels, but comprehensive N2O budgets also incorporate less prominent factors such as wetlands. Freshwater wetland GHG flux estimates, however, have high uncertainty, and wetlands have been identified as both sources and sinks. Here, we analyzed a regional database of >26,000 N2O chamber flux measurements sampled across >150 wetlands from the Prairie Pothole Region (PPR) in the Great Plains of North America. Our goal was to identify important land use and hydrologic drivers of N2O flux to help reduce uncertainty in N2O models, and to incorporate these drivers into an upscaled estimate of wetland N2O emissions from the U.S. portion of the PPR. Within individual wetlands, exposed soils with no standing water, such as along wetland edges, were hotspots that accounted for greater than 90% of wetland N2O emissions. In contrast wet (i.e., ponded) areas had minimal or negative N2O flux. N2O flux from wetlands nested within croplands (16.3–17.3 μg N2O m−2 hr−1) was, in some instances, nearly double that from wetlands within grasslands (9.2–14.4 μg N2O m−2 h−1). We estimated that seasonal N2O flux from PPR wetlands equated to roughly 0.2% (1.04 Tg CO2 equivalents) of the U.S. N2O budget (c. 2019). Overall, even though PPR wetlands are a small net source of N2O to the atmosphere, their emissions are negligible relative to agricultural soil management. Policy and management to restore wetland hydrology and surrounding uplands from cropland to grasslands can reduce landscape N2O fluxes. Future activities focused on wetland N2O flux would benefit from inclusion of adjacent land use and hydrologic factors, as well as from incorporation of temporally dynamic ponded wetland areas.

Potential Applications of Land Treatment Systems for Disinfectant-Rich Wastewater in Response to the COVID-19 Health Protocol: A Narrative Review

Introduction: The use of antiseptics and disinfectants in daily health protocols has a consequence of changing the quality of wastewater to be toxic to microbes. As a result, microbiological wastewater treatment has the potential to not be processed properly. To solve the problem of disinfectant-rich wastewater, a plant-based treatment method can be useful, the implementation of which is a land treatment system for wastewater.&#x0D; Materials and Methods: The data collection method was carried out through the Mendeley Reference Manager, searching for articles online, and placing the terms “land treatment system”, and “disinfectant-rich wastewater”. The selected articles were up-to-date and had a significant relationship between the two terms.&#x0D; Results: This sanitation system can be a stretch of land and/or a pond of water, on which plants can grow and process. Normal concentrations of disinfectants for microbial elimination had no negative effects on the growth of various types of plants. Plants continue to live in the stress of water rich in disinfectants, as a condition of their ability to treat wastewater. The involvement of various wastewater treatment media makes evapotranspiration dry bed and evapotranspiration wet bed or wetland ponds capable of processing various pollutants. This approach can be implemented for on-site and off-site sanitation system.&#x0D; Conclusion: In this context, under conditions of enrichment of disinfectants in wastewater during the COVID-19 era, the land treatment system becomes feasible to solve the problem of changing the quality of wastewater.

Removal of Urban-Use Insecticides in a Large Open-Water Wetland Pond

Worsening freshwater scarcity has heightened the need for treatment technologies capable of eliminating chemical and biological contaminants to allow for the beneficial use of traditionally underutilized water resources. In urbanized arid and semiarid regions such as California, urban drainage represents an increasingly important water source for augmenting water supply. However, monitoring shows that urban streams are contaminated ubiquitously with urban-use insecticides (e.g., pyrethroids and fipronil) that have broad-spectrum toxicity. In this study, a large open-water wetland pond (OWWP), characterized by shallow water depth and the absence of permanent vegetation, was evaluated for the removal of pyrethroids and fipronil (and its biologically active degradates). Concentration-based removal and changes in the pesticide mass flux were calculated to determine the efficacy of the OWWP. Toxic units for indicator aquatic invertebrates were estimated before and after the OWWP treatment to determine reductions in potential aquatic toxicity. Contaminant concentrations in water and sediment consistently decreased as the water was moving through the OWWP. Concentration-based removals were 44.2–100% for fipronil compounds, 61.8–100% for bifenthrin, and 47.3–92.7% for cyfluthrin, and the removal was attributed to sedimentation, in situ microbial degradation, and photolysis. The mitigation of these urban-use insecticides by the OWWP was similar to that of a densely vegetated constructed wetland at the same site. Therefore, OWWPs represent a low-maintenance and effective wetland configuration for large-scale water reclamation and may be particularly useful for arid and semiarid regions with favorable meteorological conditions (e.g., intense sunshine and high temperature).

The ecology of coastal wetland ponds created by diamond mining in southern Namibia. 2. Saltmarsh vegetation

Diamond mining on the southern Namibian coastline has created multiple large coastal ponds of up to 380 000 m2 adjacent to the coastline, as the sea overtops erected seawalls or seeps into excavated areas. These ponds span ages of 1–38 years. We investigated whether the ponds offer an environment for the establishment, growth and dispersal of saltmarsh vegetation along the coast, which is otherwise devoid of natural wetlands apart from at the Orange River estuary and Lüderitz Bay. Most ponds supported saltmarshes, but they comprised only a single species, Salicornia natalensis. The abundance of this succulent, mat-forming, salt-tolerant plant was greatest around old ponds, but its health decreased with increasing age and hence salinity of the ponds. The orientation of saltmarshes around the ponds was correlated with prevailing wind direction, suggesting that wind determines dispersal of this plant along the coast. However, any saltmarsh communities that have developed will be disturbed by possible future mining activities. In addition, once mining ends, the saltmarshes will become stressed owing to rising salinities as ponds age. Nevertheless, the ponds are capable of supporting saltmarshes for up to 15 years, and new ponds will be created as mining progresses; this offers an ongoing opportunity for the ponds to serve as ‘stepping stones’ in the dispersal and establishment of S. natalensis along the coast.