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• A 5-year study was conducted to identify the effects of burning on SOC in a wetland. • Prescribed burning significantly enhances the contents of labile soil organic carbons. • Significant variations of soil carbons mainly due to increased plant biomass. • Total SOC and heavy fraction are not sensitive to annual prescribed burning. Fire is a common disturbance both from natural source and anthropogenic activities and an important factor in driving the variation of soil organic carbons. A 5-year study was conducted to examine the influence of annual prescribed fire on soil organic carbon (SOC) fraction in a fire-prone plant community, Triarrhena lutarioriparia community, in Poyang Lake, China. The results showed that after burning the contents of dissolved organic carbon (DOC), soil microbial biomass carbon (SMBC) and light fraction organic carbon (LFOC) increased significantly from 78.53 mg/kg to 131.72 mg/kg, 365.58 mg/kg to 603.42 mg/kg, and 14.82 g/kg to 20.56 g/kg, respectively, during the 5-year studying period. On the other hand, the contents of total SOC and heavy fraction organic carbon (HFOC) only increased slightly from 53.67 g/kg to 61.39 g/kg and 33.45 g/kg to 37.46 g/kg, respectively. The results strongly suggested that DOC was more sensitive to the prescribed fire than SOC. Moreover, the annual ratios of DOC, SMBC and LFOC to SOC significantly increased after burn treatments. Taken together, prescribed fire could greatly increase the contents of soil active organic carbons, and enhance the carbon cycle in Poyang Lake. Thus, it could be taken as an exercisable measure to improve the carbon capacity and maintain the soil productivity in the lake wetland. [ABSTRACT FROM AUTHOR]

• Water and salt balance is a key issue in the recovery of plateau salt marsh wetland. • We establish a water-salt dynamic model using remote sensing and water quality data. • The dynamic model calculates the ideal value of wetland water volume 20.17 × 106 m3. • Simulating precipitation water transfer be good at the wetland restoration. We analysed the eco-hydrological characteristics of the Bojiang Haizi River basin, which is the location of the Erdos Larus Relictus Nature Reserve plateau salt marsh wetland. The study found that the restoration of the plateau salt marsh is more of a water quality problem than a water quantity problem. Simply maintaining the balance of water volume without considering water quality will destroy the original stable ecosystem. Therefore, water balance analysis was conducted for the overall water resources in the basin on the basis of simulated data of the Soil and Water Assessment Tool module. We examined remote sensing and water quality monitoring data via geographic information system-3D technology to meet the requirements of water quality and quantity in wetland restoration. We established the hydrological dynamic relationship model of lake storage capacity-elevation-area-salinity and found that the lake presents an alternating cyclic rule of salt accumulation and dilution during seasonal changes. This pattern is an important guarantee for the healthy and sustainable development of the salt marsh wetland. Lastly, the survival salinity of the organism was selected as the target salinity (5 g/L), and the corresponding target water amount was simulated as 20.17 × 106 m3; the target lake area was 9.48 km2. Through an analysis of three water transfer scenarios, we found that under the optimum balance condition between water quantity and salt concentration, simulating the water transfer mode in precipitation replenishment is an effective means to restore the wetland during breeding season. The findings of this study may improve our understanding of the eco-hydrological characteristics of plateau salt marsh wetlands and help managers protect and restore water balance using water–salt dynamic models. [ABSTRACT FROM AUTHOR]

• CO 2 fluxes of a costal wetland were measured with static chamber technique. • CO 2 sinks capacity were different among different vegetated flats. • Spartina alterniflora invasion enhanced CO 2 sink capacity of the wetland ecosystem. • Mud flat can act as a CO 2 sink was likely to be caused by the inorganic process. This study applied the static chamber method to evaluate the CO 2 fluxes from December 2013 to October 2014 in the coastal wetland of Jiaozhou Bay, China. The study area was divided into Spartina alterniflora flat, Phragmites australis flat, Suaeda salsa flat and mud flat. Results showed that net ecosystem CO 2 exchange (NEE) presented obviously temporal and spatial variations during growing season, and slight fluctuation in non-growing season. Vegetated flats (S. alterniflora flat, P. australis flat and S. salsa flat) acted as CO 2 sinks during growing season and CO 2 sources during non-growing season; while mud flat acted as a CO 2 sink through the entire period. Over the growing season, the estimated total NEE were −1202.83 g CO 2 m−2 in S. alterniflora flat, −1129.16 g CO 2 m−2 in P. australis flat and −237.43 g CO 2 m−2 in S. salsa flat, respectively. Daytime NEE were significantly exponential related to light intensity in S. alterniflora flat and P. australis flat; whereas no overt exponential relationship was found between these two factors in S. salsa flat. In P. australis flat, ecosystem respiration (R eco) and gross primary production (GPP) in growing season were estimated to be 2874.05 and 1744.89 g CO 2 m−2, respectively; R eco was significantly exponential related to air temperature and soil temperature at different depths, among which soil temperature at the depth of 5 cm was the most remarkable; temperature sensitivity (Q 10) of R eco ranged from 2.72 to 3.67. Aboveground biomass of P. australis over the entire growing season showed non-linear relationships with NEE, GPP, and R eco ; while it showed significant linear relationships with these three factors during early and peak growing season. As for the mud flat acting as a CO 2 sink, it is supposed to be caused by inorganic process, however the mechanism is not definite. Further research on the long-term and complete observations of CO 2 exchange at the mud flat-atmosphere interface is necessary. [ABSTRACT FROM AUTHOR]

• Two differently dimensioned, located and aged CWs were monitored with sensors. • Retentions (%) were higher in the Hovi CW with larger CW-to-catchment area ratio. • Hovi is also 11 years older and its catchment has higher share agricultural land. • Retentions (%) of dissolved nutrient fractions seem to increase as wetland ages. • Our experiences with automatic measuring devices were positive. Constructed wetlands (CWs) are recognized as a useful method to reduce sediment and nutrient loading from arable land to surface waters. Automatic monitoring systems with continuously measuring sensors were utilized for several years to obtain accurate, up-to-date information of the retention performance of two differently dimensioned and located CWs in agricultural catchments in southern Finland. Here, results derived from the data recorded by the sensors measuring height, turbidity and nitrate-nitrogen (NO 3 -N) concentration of the water entering and exiting the Hovi (established in 1998) and Rantamo-Seitteli (est. in 2009) CWs are presented. Study periods ended in autumn 2014 and they lasted 7 years at Hovi and 4.5 years at Rantamo-Seitteli. Annual total suspended solids (TSS), total phosphorus (TP) and total nitrogen (TN) per cent retentions were much higher in the older, more generously dimensioned (CW-to-catchment area ratio 5%) Hovi CW (TSS 74%, TP 58% and TN 54% on average during 7 years) than in the newer, more scantly dimensioned (CW-to-catchment area ratio 1.3%) Rantamo-Seitteli CW (TSS 7%, TP 12% and TN 9% on average during 4.5 years). Moreover, the annual retentions of the Rantamo-Seitteli CW appeared to decrease with increasing runoff, while the retentions at Hovi were not affected by runoff fluctuations. In terms of TSS and TP retentions in the Hovi CW, they were in this study at similar levels to those observed shortly after the establishment of the CW. Meanwhile, the retention of dissolved nutrient fractions, i.e. NO 3 -N and dissolved reactive P (DRP, based on water sampling) at Hovi were clearly higher in this than in the previous study. The results confirm the importance of CW dimensioning and locating near the sources of loading, and refer to improved performance as CWs get older with increasing vegetation and biological activity. Our experiences of CW measurements with sensors have been positive. The information obtained with new technology has provided retention estimates that are more accurate than they would have been if they were derived from sparse grab sampling. [ABSTRACT FROM AUTHOR]

• Wetlands with fresh water inflow had higher accretion rates than areas no inflow. • Wetlands with fresh water inflow had higher productivity than areas with no inflow. • Tree ring data showed higher stem growth in wetlands with inflow than ones without. • Removal efficiencies for TN and TP averaged between 65 and 90%. • NO 3 removal efficiency averaged between 90 and 100%. The term 'assimilation wetland' has been applied to natural wetlands in Louisiana into which disinfected, secondarily treated municipal effluent is discharged with the dual purpose of improving regional water quality and enhancing vegetation productivity and soil accretion. Some municipalities began discharging treated effluent into wetlands prior to state regulations, which began in 1992. Here we review data and observations from five assimilation wetlands in the Mississippi River Delta receiving discharge of treated effluent for 26–70 years. In addition, we examine two adjacent forested wetlands, one that receives periodic Mississippi River input and one that does not. Information from these sites provides insight into how long-term nutrient input impacts coastal wetlands. Analysis of tree-ring, leaf litter, accretion, and water quality data shows that input of freshwater containing nutrients and sediments leads to enhanced wetland productivity and soil accretion via increased organic matter burial. In addition, long-term data indicate that assimilation wetlands continue to be nutrient sinks even after decades of effluent discharge, with both nitrogen and phosphorus reduced to background levels. Collectively, these data demonstrate that wetlands benefit from long-term discharge of treated municipal effluent. Properly managed wetland assimilation systems can function for long periods and lead to enhancement of degrading wetland communities in coastal Louisiana. [ABSTRACT FROM AUTHOR]

• Metal removal is assessed in a wetland implemented in drained agricultural catchment. • Time-integrated tools show efficient mitigation in dissolved and particulate fractions. • Bioaccumulation based-tools reveal metal bioavailability reduced at the outlet. • Spatial-temporal monitoring supports the central role of sediments in metal trapping. • The wetland has a beneficial effect for local invertebrates in terms of exposure. Constructed wetlands are designed to mitigate nutrient and pesticide fluxes from agricultural catchments. Nevertheless, information on their efficiency in removing non-degradable contaminants such as metals is still scarce. This study aimed to explore the metallic signature and fate of metals within the Rampillon wetland (France) receiving water from a drained 355-ha catchment under intensive agriculture. Original monitoring coupling classic, time-integrated and bioaccumulation-based tools was achieved to characterise spatiotemporal dynamics of various metals (As, Cd, Cr, Co, Cu, Mn, Ni, Pb, Sb, Se and Zn). To assess metal inflows and mitigation, samples of dissolved and particulate metals were collected bimonthly at the inlet and outlet of the wetland over 3 months. Simultaneously, time-integrated (sediment traps and passive samplers) and bioaccumulation-based (caged gammarids and biofilms) tools were deployed to monitor temporal changes in metal speciation and bioavailability. To gain insight into the spatial distribution of metals between abiotic and biotic matrices, sediments and indigenous invertebrates with contrasted ecologies were sampled in different cells of the wetland. The results showed time-integrated tools were more suitable than bimonthly samples to quantify metal mitigations because of temporal fluctuations and low contamination levels. Significant mitigations were thus observed in trapped sediments for all metals (ranged 11–23%, except Mn) as well as in the DGT-labile fraction for Cd, Cr, Co, Mn and Ni (ranged 13–51%). Bioaccumulation levels in biofilms also revealed a decrease in metal bioavailability at the outlet. Furthermore, the spatial survey supported the central role of sediments in metal trapping and the beneficial effect of this wetland for local biodiversity in terms of exposure. To conclude, this study provides valuable information on the ecodynamics and bioavailability of metals required for sustainable management of such artificial ecosystems and furthermore, of agricultural areas. [ABSTRACT FROM AUTHOR]

Atmospheric nitrogen (N) deposition caused by human activities has been shown to have significant impacts on ecosystem structure and function, but the reported impacts have been inconsistent among studies. To test the effects of N deposition on a salinized reed wetland, we built a long-term nitrogen deposition experimental platform in the Yellow River Delta (YRD), China. The present study investigated soil chemical properties, soil enzyme activities and plant growth parameters after five years of N deposition. Results showed that the concentration of NH 4 -N and NO 3 -N increased significantly with the increasing level of nitrogen addition, but no significant influences were observed in total nitrogen (TN), total organic carbon (TOC) and available phosphorous (AP) across N addition treatments. Higher amounts of N addition significantly increased the urease activity (Ure) and alkaline phosphatase activity (Alp), but did not enhance the activity of invertase (Inv). The activities of Ure and Alp were positively correlated with the concentration of soil NO 3 -N, TN and TC, respectively, but negatively correlated to soil salt content. Meanwhile, the plant height and productivity were significantly stimulated, and the surface soil salt content decreased significantly. The results suggest that atmospheric N deposition may help improve the function of salinized reed wetland ecosystems in the YRD by increasing soil nutrient content, stimulating soil enzyme activity and enhancing plant production. [ABSTRACT FROM AUTHOR]

• In a Phragmites australis wetland, 7-year warming significantly increased total organic C and total N in top soil layer, but it exerted no effect on total P. • Warming exerted no effect on microbial biomass C or invertase activity, but it significantly increased microbial biomass N, microbial biomass P, phosphatase, and urease activities in 0–10 cm soil layer. • In the wetland, climate warming may increase soil organic C pools while exerting no effect on microbial C decomposition, whereas microbial N and P cycling may be enhanced. Wetlands play an important role in global carbon (C) cycling. However, little is known about the effects of climate warming on wetland C cycling, which may bias our prediction of wetland functioning under global climate change. This study was undertaken to examine the potential changes in soil C, nitrogen (N) and phosphorus (P) pools and the related microbial activities after 7 years of in-situ experimental warming by open-top chambers (OTCs) in a Phragmites wetland in the Yangtze Estuary. The mean soil temperature, moisture, and salinity in both the 0–10 cm and 10–40 cm soil layers were significantly increased by the warming treatment. In the upper 10 cm soil layer, significant increases in total organic C (TOC) and total N (TN) were observed under the warming treatment, while the phenomenon were further clarified by comparing the year-round data in the warming plots between 2008 and 2015; However, the molar C/molar N ratio (C/N) and total phosphorus (TP) were not affected. In both layers, microbial biomass C (MBC) and the molar MBC /molar MBN ratio (MBC / MBN) showed no significant responses, but microbial biomass N (MBN) and microbial biomass P (MBP) were increased by warming. Warming did not affect MBC / TOC , but it significantly increased both MBN / TN and MBP/TP throughout the 0–40 cm soil profile. Invertase activity was not affected in the 0–40 cm soil profile. The acid phosphatase, alkaline phosphatase, and urease activities in the upper 10 cm soil layer were increased by warming. Only alkaline phosphatase activity was increased by warming in the 10–40 cm soil layer. These field-experimental warming results suggested that in temperate P. australis wetlands without tidal impacts, climate warming might increase the soil organic C pools while exerting no effect on microbial C decomposition, whereas the N and P cycling that is mediated by soil microbes might be enhanced by moderate warming. [ABSTRACT FROM AUTHOR]

The first three years of net ecosystem exchange of carbon dioxide (NEE) for a wetland constructed on bitumen mine tailings show its progression towards becoming an annual carbon dioxide sink. • A reclaimed wetland was a source of CO 2 for the first 2 years after construction. • In year 3 the wettest region absorbed 77 g C m−2, similar to natural peatlands. • Drier regions remained net CO 2 sources due to greater rates of soil respiration. Northern peatlands contain up to 20% of the ∼3000 Pg of global soil organic carbon. Carbon-rich peatlands cover upwards of 65% of the landscape in northern Canada where resource extraction activities disturb both the carbon pools and the future carbon sequestration capacity of the landscape. Previous estimates of the carbon losses from this disturbance predict a complete loss of the region's peatland carbon pool. Mining industries operating in these sensitive environments have recently begun constructing closure landscapes which are intended to develop carbon cycle processes similar to undisturbed northern peatlands. This study investigates eddy covariance fluxes of carbon dioxide (CO 2) at one of Canada's first fully constructed boreal plains watersheds, the Sandhill Fen Watershed. During the first three years since inception, only the lowland region had an annual net ecosystem exchange of CO 2 (NEE) indicative of increasing CO 2 sink potential. The lowland region was characterized by saturated salvaged peat soils, standing water, thriving communities of Typha and Carex spp. and was a net CO 2 sink of 77 g C m−2 in the third year. At the same time the upland and the midland regions characterized by moist salvaged peat soils and a mix of herbaceous, shrub and planted Picea glauca and Pinus banksiana remained net sources of CO 2. Despite similar rates of gross primary production, ecosystem and plot-level respiration rates in the lowland were significantly lower than in the midland region, likely due to very low reduction potentials within the lowland's saturated soils. With no other significant outflows of carbon, the lowland of the Sandhill Fen Watershed may be in the early stages of organic matter accumulation. Due to limited oxidation of the salvaged peat substrate in the lowland region, wetland reclamation employing these techniques may reduce the disturbance loss of the carbon pool in the boreal plains. [ABSTRACT FROM AUTHOR]

• In-situ coagulation system successfully employed for water quality improvement. • Al dosing resulted in higher removal efficiency than Fe dosing. • FDOM and UV254 suitable as source water DOC surrogate. • FDOM and UV254 as DOC surrogates after coagulant application presented challenges. Agricultural production on wetland soils can be significant sources of dissolved organic carbon (DOC), disinfection byproduct precursors, mercury and nutrients to downstream water bodies and accelerate land subsidence. Presented as a potential solution for in-situ water quality improvement and land subsidence mitigation, chemically enhanced treatment wetlands (CETWs) were used to leverage both coagulation and wetland processes. In this study, we evaluated the performance of coagulants ferric sulfate (Fe dosing) and polyaluminum chloride (Al dosing) to remove pollutants from agricultural drain water using the coagulation system designed for CETWs. Both coagulation treatments removed over 70% DOC from source waters, resulting in removal efficiencies (mg-DOC removed per mg-metal dosed) of 1 under Al dosing and 0.5 under Fe dosing. Coagulation by both treatments preferentially removed UV254 active compounds compared to the bulk DOC concentration, suggesting coagulation targeted aromatics more effectively. Phosphates and haloacetic acids were also removed more readily, whereas trihalomethanes, dissolved organic nitrogen and filtered mercury species were removed at similar or lower rates than DOC. Dissolved inorganic nitrogen was not amenable to coagulation and removal was not observed. Freundlich, Langmuir and Monod models explained 33% of the variance in DOC removal for Al dosing and 78–89% of the variance for Fe dosing. All three models indicated Al dosing had higher removal efficiency and affinity for DOC than Fe dosing under study conditions, but when used to predict maximum removal efficiency there was no cohesiveness between the three models due to different model assumptions. Consideration of fluorescence dissolved organic matter and UV254 as surrogates for DOC concentration showed both were equally suitable before coagulant application, but as surrogates after coagulant application, neither could be deemed more fit as a surrogate since both were shown suitable for different treatment scenarios. [ABSTRACT FROM AUTHOR]

• Continuous tracking for soil sulfur storage with a maximum of 13 years based on the invasion time of exotic Spartina alterniflora. • Changes for soil sulfur storage in different seasons with the invasion of Spartina alterniflora. • Varieties for soil sulfur storage in different depths. • Compared with the soil sulfur storage between exotic Spartina alterniflora , native species S. mariqueter and unvegetated mudflats. • Explored the relationships between sulfur and environmental factors. With an aim to determine whether Spartina alterniflora actively changes the habitat environment, thus facilitating its successful competition over native species, a field experiment was carried out at the Jiuduansha Wetland National Nature Reserve. Sulfur concentrations in the soil sediments were compared among wetlands dominated by the exotic Spartina alterniflora , the co-occurring native species S. mariqueter and unvegetated mudflat. The results show that the soil sulfur concentrations in the Spartina alterniflora community showed significant spatiotemporal variability with the years since invasion. The S. alterniflora community contained the highest concentrations of sulfur in the soil sediment. Moreover, the sulfur concentrations were higher in the initial invasion area than at the edges of the invading area. The was little difference in soil sulfur concentrations between communities containing native species S. mariqueter and unvegetated mudflat. There were significant correlations between soil sulfur concentrations and carbon and nitrogen concentrations; the soil nitrogen concentrations were negatively correlated with the sulfur concentrations, and the carbon concentrations were positively correlated with the sulfur concentrations. In different seasons, the concentration of sulfur is relatively higher in spring than which in other seasons. Furthermore, the sulfur concentrations at different soil depths also exhibited significant changes with depths. In addition, the soil sulfur concentrations associated with S. alterniflora also showed a trend of increasing first and then decreasing with depth, the soil sulfur concentrations in S. alterniflora soils were obviously higher than those in the S. mariqueter community and unvegetated mudflat, the maximum concentrations in S. alterniflora soils occurred at the depth of 40–60 cm. The findings of this study indicate that S. alterniflora increases wetland sulfur storage, which may explain the mechanism of expansion of S. alterniflora in the Jiuduansha Wetland. [ABSTRACT FROM AUTHOR]

Human activities have changed global nitrogen (N) cycling in the last decades. Global warming has potential to alter the decomposition of organic carbon. At the moment the effects of inorganic and organic N additions on litter decomposition, alone and in combination with increasing temperature, are not well known. A filed experiment of N addition (nitrate, ammonium and organic N) was conducted in the reed (Phragmites australis) wetlands in the Yellow River Delta, China. At the end of second growing season, the standing litter (leaf and stem) of reed were collected, and were incubated (90 days) to determine the combined effects of N forms and increasing temperature on litter decomposition. The CO 2 production was defined as litter decomposition. The results showed that increasing temperature accelerated stem litter decomposition, and had no effect on leaf litter decomposition. Nitrogen additions inhibited leaf and stem litter decomposition due to the decrease in C/N ratio. Ammonium and organic N additions had larger inhibitory effects on stem litter decomposition compared with nitrate addition. This highlights the importance of differentiating the effects of N forms on litter decomposition. Moreover, the combined effect of N additions and increasing temperature on both litter decomposition was antagonistic due to the decreased Q 10 value of litter decomposition after N additions. Our results suggest that the negative effect of N addition on litter decomposition may be enhanced by increasing temperature in the near future. [ABSTRACT FROM AUTHOR]

Treatment wetlands are ecological systems that are engineered to improve polluted water quality through macrophyte, soil, and microbial remediation and are used commonly for urban and agricultural runoff treatment. However, constructed wetlands used for marine aquaculture effluent treatments are understudied when compared to their freshwater counterpart. We compared the nutrient retention and the microbial communities of two types of constructed wetland mesocosms, a vertical-flow treatment wetland (VFTW) and floating treatment wetland (FTW) in subtropical south Florida. To enhance nutrient retention efficiency, we implemented biodegradable plastic (polycaprolactone), as an external carbon source and monitored the performance of VFTW and FTW for the treatment of marine aquaculture effluent. Polycaprolactone surface were covered by various cyanobacterial genera including Oscillatoria , Leptolyngbya , Brasilonema , and Trichormus and some plastic-degrading bacteria such as Pseudomonas. The presence of a biodegradable plastic in FTW improved the overall performance of nitrogen removal (nitrite plus nitrate) by 14% through denitrification. The pattern of nutrient removal between two treatment wetland mesocosms were significantly different (p < 0.01), with over 87–91% retention of total nitrogen in VFTW and no retention in FTW, the latter due to poor retention of nitrite plus nitrate and production of organic nitrogen from the system not present in inflow waters. Total phosphorus was retained in both mesocosm types, with higher retention (74–81%) in the VFTW than in the FTW (17–40%). The nutrient retention in VFTW was higher overall compared with FTW mesocosms regardless of biodegradable plastic presence. [ABSTRACT FROM AUTHOR]

Iron cycles is essential for the transition of matter and energy in wetland ecosystems. The tidal hydrology is a critical factor controlling soil iron biogeochemistry in estuarine wetland, but it remains unclear how iron oxides response to tidal hydrologic regime. A field experiment was manipulated in the Yellow River Estuary wetland for 23 months to differentiate change in iron oxides of freshwater marsh soil under different tidal hydrologic regimes. In June 2019, soil cores were collected in the freshwater marsh on the supratidal zone (FPA), and translocated to be cultured in the tidal salt marshes on the intertidal zone (SPA, TC and SS). Over 23 months, tidal hydrologic regime had obviously affected soil properties and iron oxides. Under the tidal regime, there was an increase in soil pH and electric conductivity (EC), and a decrease in soil water content (SWC), total nitrogen (TN), total phosphorus (TP) and total organic carbon (TOC). A total decrease was found in the contents of soil iron (Fe T), iron oxides (Fe p , complexed iron; Fe o , amorphous iron; Fe d , free iron) and their ratios (Fe p /Fe d , Fe o /Fe d and Fe d /Fe T). The duration of tidal hydrology affected the contents of iron oxides and their ratios, i.e., Fe T and Fe d decreased with culture time in all sites while Fe p , Fe o and the ratios increased in the supratidal site. Iron oxides and their ratios were positively correlated to redox potential, organic carbon and nutrients, and negatively correlated to soil pH and salinity. The results indicate that tidal hydrologic regime could decrease the contents of soil iron oxides and their activation when freshwater marsh exposed to tide events. [Display omitted] • A field experiment along a hydrologic gradient was manipulated. • Tidal hydrology had effects on soil properties and contents of iron oxides. • Tidal action decreased the contents of iron oxides and their activation. • Changes in iron oxides under tidal regimes were related to soil properties. [ABSTRACT FROM AUTHOR]

Biochar (BC) application for improving soil quality and carbon sequestration has generated great interest for scientists and policy makers. BC can influence soil organic carbon (SOC) mineralization through priming effects. Positive, negative or no priming effects on C mineralization has been observed following BC additions to soils. However, uncertainty still remains about the influence of biochar on SOC mineralization in the coastal wetland soils of the Yellow River Delta, China. Therefore, a five months of incubation experiment using the coastal wetland soil was conducted to investigate the effects of adding BC produced from peanut shell at 350 °C on SOC mineralization at the rates of 0% (0%BC), 0.1% (0.1%BC), 1% (1%BC) and 3% (3%BC) (w/w). BC addition increased the cumulative CO 2 emissions, indicating that the cumulative SOC mineralization was enhanced in the coastal soil by BC application. However, the increased C mineralized only accounted for 1.71%, 0.32% and 0.17% of the BC-C added in the 0.1%BC, 1%BC and 3%BC treatments, respectively. Moreover, the experimental values of SOC mineralization was much lower than that of the theoretical values in both 1%BC and 3%BC treatments, indicating that a negative priming effect occurred. This may be explained by two reasons: (1) the conversion process of SOC to dissolved inorganic C (DIC) was accelerated by BC addition, which was confirmed by SEM image; (2) the amounts of available C substrate and microorganisms decreased via the sorption of labile organic C (LOC) and microorganisms onto BC. These results suggest that BC application will enhance soil C storage in the salinized wetland soils. [ABSTRACT FROM AUTHOR]

A 16S rRNA gene multiplex 454 pyrosequencing approach was used to characterize the structure of the bacterial community in subsurface flow constructed wetlands planted with Typha angustifolia and unplanted wetland mesocosms receiving ibuprofen-enriched wastewater at a concentration of 250 μg L −1 . The removal efficiency of ibuprofen (IBP) in the planted beds (78.5%) was significantly higher than that in the unplanted beds (57.9%) ( P ≤ 0.05). The presence of ibuprofen significantly ( P ≤ 0.05) reduced the diversity of the bacterial community. In total, 20 phyla comprising 265 genera were identified. The most predominant phyla were Firmicutes (27.6%), Actinobacteria (26.0%) and Proteobacteria (24.9%), making up 57–95% of the 16S rDNA sequences. Other dominating phyla in wetland soils were Chloroflexi (7.3%), Bacteroidetes (2.7%), Synergistetes (2.1%), and Acidobacteria (2.0%). A distinct profile of bacterial community in the wetland mesocosms was observed after IBP enrichment. IBP-enrichment enhanced the relative abundance of Actinobacteria, Bacilli and γ-Proteobacteria at class level. The efficient ibuprofen removal observed in this study suggested that the IBP-enriched wetland systems may have selected a restricted group of bacteria that was able to survive best in the disturbed condition and participate in the IBP biodegradation. Our findings also indicated that the presence of macrophytes may have a vital impact on the microbial community and planted wetlands may be more robust and buffered against significant shifts in microbial composition in response to IBP-disturbance. [ABSTRACT FROM AUTHOR]

Due to the importance of wetlands as a global carbon pool, explicit research on and management of the carbon storage of wetlands have drawn much attention. Within a single climatic zone, South Korea has various types of inland wetlands such as tidal salt marshes, freshwater lakes, rivers and peatlands, thereby providing an excellent platform for scientific investigation to identify patterns and key controlling factors of carbon budget in different inland wetlands. We estimated the amount of soil organic carbon (SOC) of 2444 inland wetlands in South Korea by cluster analysis and Monte-Carlo simulation using data from South Korea's National Wetland Inventory and their economic values by literature review. In addition, we identified key controlling factors that are closely related to SOC of 34 inland wetlands by correlation analysis and ANOVA test. We found that the total SOC stock of inland wetlands in South Korea is 16.3 ± 0.4 TgC (22.3 ± 0.6 kgC m−2), which is 5.3–5.5% of the total SOC stock of the country, and the annual carbon sequestration rate is 60.7 ± 9.8 gC m−2 yr−1. The economic value of the total SOC stock is 2.0 ± 0.1 billion USD (2.8 ± 0.1 USD m−2), and that of the annual sequestration rate is 5.5 ± 0.9 million USD yr−1 (7.5 ± 1.2 10−3 USD m−2 yr−1). The mean atmospheric temperature and soil characteristics including water content, total nitrogen and electrical conductivity showed positive correlations with SOC, suggesting the importance of hydrology and water chemistry as key determinants of SOC. In addition, inland wetlands with different dominant plant species showed significantly different SOC, probably because primary production and chemical composition of vegetation are strongly associated with carbon input into wetlands. However, annual precipitation and soil pH showed no correlation with SOC. Our results demonstrate that the carbon budget of inland wetlands in South Korea is considerable, and its economic value is closely related to characteristics of soil and vegetation. • The total SOC stock of inland wetlands in South Korea is 16.3 ± 0.4 TgC (2.0 ± 0.1 billion USD). • The annual carbon sequestration rate of inland wetlands in South Korea is 60.7 ± 9.8 gC m−2 yr−1 (7.5 ± 1.2 10−3 USD m−2 yr−1). • The key controlling factors of inland wetlands' SOC are MAT, soil WC, TN, EC, and dominant plant species. [ABSTRACT FROM AUTHOR]

The levels, sources and health risks for PAHs collected at the national scale in China were discussed in the study. The total concentrations of 16 PAHs in nine coastal wetland soils ranged from 10.8 to 4870 ng g −1 . The sources of PAHs were apportioned by PCA, and both the carcinogenic and non-carcinogenic risks were quantitatively calculated with Monte Carlo simulation. A sensitivity analysis was performed to determine the greatest effect of input variables on the risk assessment. The results revealed that 16 PAHs mainly originated from coal combustion, natural gas combustion, diesel emission, and petrogenic source. The carcinogenic risk and non-carcinogenic risk for nine coastal wetlands were below the risk threshold value (10 −6 for carcinogenic risk, and 1 for non-carcinogenic risk, respectively), indicating no potential adverse health effects developed. Ingestion and dermal contact were the major exposure routes for PAHs risks. Exposure duration and PAHs concentration contributed most to the total risks uncertainty. This study is the first attempt to provide information on health risk of PAHs in wetland soils from a national perspective. The findings support the feasibility of development and evaluation of an implementation strategy for PAHs risks management in coastal wetland soils. [ABSTRACT FROM AUTHOR]

Abstract: The Cienega de Santa Clara in the Colorado River Delta, Mexico is a self-designed wetland system fed since 1977 by brackish groundwater diverted from the U.S. to Mexico. The vegetated upper portion of the Cienega provides habitat for endangered Yuma-Clappers rails and other marsh birds and fulfills other ecological functions. Outflow water pools in the Santa Clara Slough south of the Cienega and provides habitat for migratory shorebirds. Conditions in the Cienega and Santa Clara Slough could be altered by operation of the Yuma Desalting Plant (YDP), which will divert water from the Cienega and replace it with brine water resulting from the desalting process. Our objective was to integrate water budget components into models predicting the extent of the dominant vegetation (southern cattail, Typha domingensis Pers.) in the marsh and the area of the outflow pool below the marsh in response to different operating scenarios for the YDP. The models are intended to serve as tools for resource managers charged with maintaining this wetland complex. Unlike many wetland water budget models, this one explicitly takes into account salinity as a factor in the water budget. We modeled inflow rates ranging from 1 to 6m3 s−1 and inflow salinities ranging from 0 to 6gL−1 Total Dissolved Solids. The model indicates that if the inflow rate is reduced below the current 4–5m3 s−1 the vegetated area of the Cienega would decrease in proportion, as would the area of the outflow pool in the Santa Clara Slough. Increases in salinity will also reduce the vegetated area due to the low salt tolerance of T. domingensis. In winter about 90% of inflow water exits the Cienega into the Santa Clara Slough due to low evapotranspiration, and on an annual basis 70% of inflows exit into the Santa Clara Slough. These flushing flows maintain the salt balance in the Cienega. The Santa Clara Slough is periodically flushed by spring tides, making this a sustainable, open wetland system in its present state. [Copyright &y& Elsevier]

Abstract: The transport of dissolved inorganic nitrogen in wetlands was investigated in the Yeyahu National Preserve of Beijing, China, from July to December 2011. Stable isotope of nitrogen (15N) as NH4 + was added to experimental mesocosms vegetated by seven common wetland plants. The 15N abundance in soil and various plant parts were measured at prescribed time intervals during the 49-day experimental period. Rapid 15N enrichments were found in soil and aquatic plants during the first sampling event at day 3 and typically increased linearly during the experimental period. Highest 15N enrichment was found in submerged plants, followed by emergent plants and soil. No differences in δ 15N values were found among leaves and stems of all submerged plants (Potamogeton pusillus, Potamogeton perfoliatus, Najas marina, Ceratophyllum demersum), suggesting that these plant structures are equally effective in nitrogen assimilation. The roots of P. perfoliatus displayed the lowest enrichment compared to the stems and leaves. Such results indicate that submerged plant roots may have a relatively weak role in nitrogen assimilation. The two emergent plants (Phragmites australis and Typha orientalis) showed no differences in δ 15N values among all plant parts, suggesting rapid translocation of nitrogen from roots to other portions. This experiment demonstrates that wetland soil and plant stems and leaves are major sinks for dissolved nitrogen from the surface water and provides valuable insight into nitrogen retention and transport pathways in various wetland plants. [Copyright &y& Elsevier]

Abstract: We investigated structural soil attributes, the development of denitrification potential (DP), and their relations in created and natural non-tidal freshwater wetlands in Virginia. Soil attributes included soil organic matter (SOM), total organic carbon (TOC), total nitrogen (TN), pH, gravimetric soil moisture (GSM), and bulk density (Db). A subset of soil attributes were analyzed across the sites, using Euclidean cluster analysis, resulting in three soil condition (SC) groups of increasing wetland soil development (i.e., SC1

Abstract: Wetland creation is a common practice for compensatory mitigation in the United States. Vegetation attributes have been used as a quick measure of mitigation success in most post-creation monitoring, while little attention has been paid to soils that provide the substrate for flora and fauna to establish and develop. Created wetland soils are often found not indicative of ‘hydric soil’ with a lack of development of physicochemical properties (i.e., bulk density, moisture content, and carbon and nitrogen contents) comparable to those in natural wetlands. Moreover, soil bacterial communities are rarely examined though they are integrally involved in biogeochemical functions that are critical for ecosystem development in created wetlands. We analyzed soil physicochemistry and profiled soil bacterial community structure using amplicon length heterogeneity polymerase chain reaction (LH-PCR) of 16S ribosomal DNA in three relatively young wetlands (<10 years old) created in the Piedmont region of Virginia. We examined the data by site and by specific conditions of each site (i.e., induced microtopography and hydrologic regime). Multidimensional scaling (MDS) and analysis of similarity (ANOSIM) showed clear clustering and significant differences both in soil physicochemistry (Global R =0.70, p =0.001) and in soil bacterial community profiles (Global R =0. 77, p =0.001) between sites. Soil physicochemistry (Global R =1, p =0.005) and bacterial community structure (Global R =0.79, p =0.005) of soils significantly differed by hydrologic regime within a wetland, but not by microtopography treatment. A significant association was found between physicochemistry and bacterial community structure in wetland soils, revealing a close link between two attributes (ρ =0.39, p =0.002). C/N (carbon to nitrogen) ratio was the best predictor of soil bacterial community patterns (ρ =0.56, p =0.001). The diversity of soil bacterial community (Shannon''s H′) differed between sites with a slightly higher diversity observed in a relatively older created wetland, and seemed also fairly determined by hydrologic regime of a site, with a relatively dry site being more diverse. [Copyright &y& Elsevier]

The moisture availability is of great significance to the physical, chemical and biological processes of soil, however, information regarding how freeze-thaw cycles (FTCs) affect the bacterial community of soil with different moisture contents is limited. In this work, we studied the relationship between FTCs and soil bacterial community under different moisture content (field capacity, FC and saturated moisture content, SMC). The results showed that FTCs decreased the richness and diversity of the soil bacterial community. Bacteria diversity were significantly decreased after the second FTC (FTC2). Thereafter, bacterial diversity with a saturated moisture content returned to the pre-freeze-thaw level, but the recovery of bacterial diversity in soil with the field capacity was lower than that of the saturated moisture content. Frequent FTCs accelerate the turnover of dissolved organic carbon DOC by affecting the carbon metabolism of microbial communities. Adjusting moisture to SMC can increase the stability of carbon. Our results provided reference to for the management of restored wetland. • Bacterial diversity and abundance decreased sharply under second freeze-thaw cycles. • Soil bacteria diversity with saturated moisture content will quickly return to the original level. • Freeze-thaw cycles accelerate the turnover of dissolved organic carbon by effecting bacterial carbon metabolism. [ABSTRACT FROM AUTHOR]

Abstract: Mercury fluxes between soil and atmosphere have often been determined by using dynamic flux chambers and micrometeorological methods to assess ecological risks. However, both systems are complex, stationary, and expensive impeding measurements of Hg emissions at various field sites. The mobile, easy to handle, and cost-effective field method to determine total gaseous mercury (TGM), according to [Böhme, F., Rinklebe, J., Stärk, H.-J., Wennrich, R., Mothes, S., Neue, H.-U., 2005. A simple field method to determine mercury volatilisation from soils. Environ. Sci. Pollut. Res. (ESPR), 12: 133–135] creates a drop in air pressure that enhance the Hg emission. We optimized the sampling set-up using an air circulation system resulting in a continuous air flow over the soil surface. Thus, a drop in air pressure can be avoided and the detected TGM emissions are closer to reality. Additional benefits are an in-ground cylinder which inhibits lateral flow of gaseous mercury and the reduced size of the glass socket facilitating handling. To test the suitability of the optimized method, TGM emissions have been quantified on a set of Hg-contaminated riverine soils. Compared with non-polluted soils, mean Hg fluxes were strongly increased (between 138 and 711ngm−2 h−1) and showed high spatial heterogeneity. Due to impacts of multiple environmental conditions that affect TGM emissions, no significant correlations have been found between Hg stocks in bulk soils and Hg fluxes. [Copyright &y& Elsevier]

Abstract: Wetlands are large carbon pools and play important roles in global carbon cycles as natural carbon sinks. This study analyzes the variation of total soil carbon with depth in two temperate (Ohio) and three tropical (humid and dry) wetlands in Costa Rica and compares their total soil C pool to determine C accumulation in wetland soils. The temperate wetlands had significantly greater (P <0.01) C pools (17.6kgCm−2) than did the wetlands located in tropical climates (9.7kgCm−2) in the top 24cm of soil. Carbon profiles showed a rapid decrease of concentrations with soil depth in the tropical sites, whereas in the temperate wetlands they tended to increase with depth, up to a maximum at 18–24cm, after which they started decreasing. The two wetlands in Ohio had about ten times the mean total C concentration of adjacent upland soils (e.g., 161gCkg−1 were measured in a central Ohio isolated forested wetland, and 17gCkg−1 in an adjacent upland site), and their soil C pools were significantly higher (P <0.01). Among the five wetland study sites, three main wetland types were identified – isolated forested, riverine flow-through, and slow-flow slough. In the top 24cm of soil, isolated forested wetlands had the greatest pool (10.8kgCm−2), significantly higher (P <0.05) than the other two types (7.9kgCm−2 in the riverine flow-though wetlands and 8.0kgCm−2 in a slowly flowing slough), indicating that the type of organic matter entering into the system and the type of wetland may be key factors in defining its soil C pool. A riverine flow-through wetland in Ohio showed a significantly higher C pool (P <0.05) in the permanently flooded location (18.5kgCm−2) than in the edge location with fluctuating hydrology, where the soil is intermittently flooded (14.6kgCm−2). [Copyright &y& Elsevier]

Wetlands play a crucial role in reducing global warming potential in response to global climate change. Large-scale reclamation and artificial restoration of coastal wetlands significantly affect the greenhouse gas methane emissions of coastal ecosystems. To comprehensively understand the difference in methane emissions between natural and reclamation-restored wetlands, the natural bare mudflat (BM – bare mudflat) in Hangzhou Bay, three types of natural vegetation wetlands (SM - Scirpus mariqueter , PA – Phragmites australis , and SA – Spartina alterniflora), and four types of reclamation-restored P. australis wetlands with different water levels (RW0 – Water level at 0 cm; RW10 – Water level at 10 cm; RW20 – Water level at 20 cm; RW30 – Water level at 30 cm) were selected to analyze the relationship between methane emissions and environmental factors through field observations and laboratory experiments. The results showed that the methane emission flux and methane production potential (MPP) of reclamation-restored wetlands were notably higher than those of natural wetlands, and the monthly dynamics in the different types of wetlands were consistent with temperature. The methane emission flux increased rapidly from April to July (summer), and reached a monotonic peak in July. Among the natural wetlands, the methane emission flux and MPP of SA were significantly higher, which was mainly driven by the soil organic carbon (SOC). In the reclamation-restored wetlands, the methane emission fluxes did not significantly differ between RW10, RW20, and RW30, but were remarkably higher than those of RW0 and natural wetlands, which was mainly driven by the water level and salinity. The differences in the MPP of the different soil layers were mainly affected by the SOC and water levels. Especially in the 0–5 cm surface soil layer of the reclamation-restored wetlands, the MPP was significantly higher, which was mainly driven by the SOC. Therefore, during the later stages of artificial reclamation-restored wetlands, appropriate water level and salinity management and other effective engineering measures should be explored to manage methane emissions during wetland restoration. • The methane emission and production potential of reclamation-restored wetlands were higher than natural wetlands. • The methane emission and production potential of natural wetlands were mainly driven by soil organic carbon. • The methane emission and production potential of reclamation-restored wetlands were jointly regulated by water level. [ABSTRACT FROM AUTHOR]

Recently, coastal land reclamation through the use of embankments has increased worldwide, and its impacts on ecosystem processes and functionality have been widely reported. However, the ecosystem nitrogen (N) cycling turnover processes following the establishment of coastal embankments remain unknown. For this study, we investigated stocks of various types of N in soils, N storage in plant subsystems, the microbial immobilization and mineralization of N, as well as soil physiochemical properties in embanked and adjacent unembanked Spartina alterniflora , Suaeda salsa , and Phragmites australis saltmarshes in the coastal wetlands of China. Coastal embankments in a S. alterniflora saltmarsh significantly decreased the total plant N storage by 50.24%, concentrations of total soil organic N (SON) by 55.16%, ammonia nitrogen (NH 4 -N) by 32.33%, nitrite nitrogen (NO 2 -N) by 41.23%, nitrate nitrogen (NO 3 -N) by 13.38%, and the value of soil net ammonification (R A) by 83.49%. However, in P. australis saltmarshes they significantly increased the total plant N storage by 160.24%, concentrations of SON by 57.28%, NH 4 -N by 7.89%, NO 2 -N by 101.76%, NO 3 -N by 32.05%, and the value of R A by 392.95%. Nevertheless, there were no significant differences in N cycling following the establishment of coastal embankments in S. salsa saltmarshes. Significant changes in the organic and inorganic soil N pools of S. alterniflora and P. australis saltmarshes were driven by plant residue inputs, which were significantly affected by decreasing soil salinity in these coastal wetlands. Furthermore, our results indicated that coastal embankments altered the immobilization of soil N and mineralization of microorganisms by influencing the growth and activities of soil microbes, which were primarily associated with changes in soil organic and inorganic N pools following the development of coastal embankments. In summary, alterations in the organic N inputs of plants were initiated by the dramatically decreased soil salinity, which was the main determinant that drove N cycling in the soil subsystems of coastal wetlands subsequent to the establishment of coastal embankments. • Coastal embankments decreased plant and soil N pools in Spartina alterniflora saltmarsh. • Coastal embankment increased plant and soil N pools in Phragmites australis saltmarsh. • Embankment had negligible effect on plant and soil N pools in Suaeda salsa saltmarsh. • Variations of plant and soil N pools were mainly driven by decreased soil salinity following coastal embankments. [ABSTRACT FROM AUTHOR]

The rainfall amount and the frequency of extreme rainfall events have been predicted to increase in the Qinghai-Tibetan Plateau during the growing season. These changes will likely affect ecosystem processes, including those that control nitrogen (N) cycling and storage; however, the direction of the changes remains unclear. In this study, we experimentally altered the amount and frequency of precipitation events during the growing season (May through October) at an alpine wetland in the Qinghai-Tibetan Plateau. The treatments included ambient rain (CK) plus 25 mm of extra water for each irrigation event but with different irrigation frequency, i.e., weekly (DF1), biweekly (DF2), every three weeks (DF3) and every four weeks (DF4). During the growing season, the N 2 O flux showed a large seasonal variation. Compared with the treatment of natural rainfall events, the increase in the rainfall amount promoted the N 2 O emission flux. As the frequency of rainfall events increased, the aboveground biomass increased significantly from 85.82 g·m−2 to 245.79 g·m−2, and the accumulated N 2 O emissions first increased and then decreased; we observed the peak of the N 2 O flux at the DF2 rainfall frequency. We also found the significant linear relationships between soil N 2 O flux, nitrate nitrogen, and microbial biomass nitrogen content. Furthermore, among the soil microbial factors, higher rainfall frequency (DF1) significantly reduced the relative abundance of the original dominant species (Alphaproteobacteria) in the studied wetland soil. Our results indicate that alpine wetlands are highly sensitive to increased precipitation variability and high frequencies of extreme rainfall events could significantly reduce N 2 O emission. Future precipitation patterns could weaken the contribution rate of wetland N 2 O emission to the global warming. • The increase in rainfall amount promotes the flux of N2O. • N2O flux presents a unimodal response to rainfall frequency. • The increase in rainfall frequency increases vegetation biomass. • The increase in rainfall frequency reduces the abundance of dominant microorganisms. • The maximum N2O flux appears in the early stage of plant. [ABSTRACT FROM AUTHOR]

This paper explores the factors impacting permit decisions of citizen wetlands boards in Virginia's localities, specifically identifying any potential sources of cognitive bias in decision making stemming from the use of heuristics and social influences. Semi-structured interviews were conducted of wetlands board chairs and board staff to understand the factors influencing decision making. While technical guidelines are found to affect the decisions of these shoreline regulators, their decisions are not free of heuristics and social influences. Past experiences and processes of compromise and negotiation with property owners are highly valued as part of the permit-approval process. The paper highlights the opportunity for effective citizen engagement in environmental management decisions and the challenges involved. [Display omitted] • Development in Virginia's tidal wetlands is regulated by local citizens boards. • Permit outcomes by boards do not align with living shorelines as preferred approach. • Reliance on memory-based heuristics in board decisions suggests cognitive biases. • Property owners are highly valued as part of the permit-seeking process. [ABSTRACT FROM AUTHOR]

Water samples were collected from a constructed wetland in Armstrong Creek, Geelong, for eight storm events. For each sampling, a single surface sample was collected at the deepest point of five equidistant transects across the wetland in the 12, 36 and 60 h following the storm events. The samples were tested for total suspended solids (TSS), total nitrogen (TN) and total phosphorous (TP). The results from the five transects were averaged and used to develop an empirical exponential decay model for the wetland. The wetland model was integrated within a catchment model based on the 1-D Stormwater Management Model (PCSWMM), which estimates the runoff from the contributing catchment into the wetland. The catchment model was calibrated/validated using water quality data collected from 8 storm events and flow data measured over a period of 22 months at sites located in Geelong. The catchment model was validated against water level measurements in the wetland showing good agreement with a correlation coefficient of 0.78 (p < 0.05). The wetland water quality model was validated against water quality data obtained from field sampling with correlation coefficient of 0.749 (p < 0.05), 0.491 (p < 0.10) and 0.856 (p < 0.05) for TSS, TN and TP respectively. A full year simulation was run using rainfall obtained for 2018 (assumed to be a typical year) to assess wetland performance. The model results show that annual loads (kg/yr) retained were 66%, 55% and 50% for TSS, TN and TP, respectively. These results exceed the design retentions of 45% for TP and TN, but not the 80% required for TSS as stipulated by the Victorian Stormwater Quality Objectives (2017). Further modelling, increasing the detention volume by raising the overflow weir crest elevation by 0.5 m resulted in an additional 6% retention in TSS. This is still insufficient to meet the 80% target. The main conclusion of this study is that through the proposed combined sampling and modelling approach, the annual wetland pollutant treatment levels within the constructed can be accurately identified. As water quality assets are designed based on annual treatment levels, this approach provides a cost-effective method of appraising wetland performance. [ABSTRACT FROM AUTHOR]

Plant communities and water chemistry properties were characterized at Sandhill Wetland; an experimental reclamation site constructed above a backfilled open pit mine in northeastern Alberta, Canada. Observations from the reclamation site were compared to 12 mature reference wetlands (10 fens and 2 marshes) to determine the type of natural wetland the site most closely resembles at its current successional stage. From this survey of 20 research plots distributed across Sandhill Wetland, 44 plant species were encountered (35 vascular plants and 9 bryophytes). Using multivariate approaches, diversity indices, and coefficient of conservatism values, results indicate areas with water levels above the soil surface at Sandhill Wetland are most comparable to regional marshes, with Typha latifolia and Carex aquatilis exhibiting the highest cover. Across the wetland periphery where water levels are several centimeters below the soil surface, plant communities were quite dissimilar from the reference sites and dominated by the grass Calamagrostis canadensis. Based on principle components analysis, we show water chemistry at Sandhill Wetland is in a state that is between marshes and saline fens. Sandhill Wetland overall possesses a unique set of structural and chemical features in the sixth year of development. In areas where water levels are above the soil surface there is potential for development into a slightly brackish marsh analogue. The successional trajectory of low water table position areas is somewhat uncertain as the wetland periphery exhibited mixed characteristics resembling those of wet meadow, riparian, and upland environments, which we did not survey. • Sandhill Wetland plant communities resemble regional marshes in some areas • Plants have sorted out into spatially distinct zones due to water level preference • Sodium concentrations have increased annually at Sandhill Wetland since inception • Sodium-tolerant plants are present at Sandhill Wetland, albeit at low abundance • Further monitoring should continue to track potential community shifts [ABSTRACT FROM AUTHOR]

The mangrove restoration wetland project in Jinjiang Estuary, Fujian Province, was started in April 2014, and the wetland was restored using vegetation restoration technology. Prior to restoration, the area was a mix of Spartina alterniflora beaches, muddy beaches, and abandoned quarries, which were not environmentally robust. Six species of mangrove plants were used in the wetland, including Kandelia obovata , Aegiceras corniculatum , Avicennia marina , Acanthus ilicifolius , Bruguiera gymnorhiza , and Rhizophora stylosa. The plants were planted according to three mixed patterns and three planting densities. Finally, the whole wetland was divided into 27 plots, and three plant-free control areas were set up in the area close to the vegetation area. In this study, 30 topsoil samples were collected (April 2019), fraction concentrations of heavy metals (Cu, Cr, Zn, and Pb), and their bioavailability and spatial distributions were determined, and the relationships between their fractions and planting patterns were analyzed. The results showed that among the nine planting patterns, the pattern " A-K-C , 0.5×0.5 m" was the most different from the other models, and the fraction of most heavy metals obtained the lowest value of soil metal content in this model. The secondary-phase fraction (SPF) of heavy metals, including acid-soluble, reducible, and oxidizable fractions, is considered to be a direct and potentially hazardous fraction to organisms. In this study, Cu, Zn, and Pb had the greatest SPFs among all the metals (35.29, 33.45, and 51.58%, respectively). Compared with the relevant results before restoration, it was found in after five years of mangrove restoration, the SPF of Cu, Cr, Zn and Pb decreased by 41.31, 22.89, 27.06, and 22.13%, respectively, indicating that the direct and potential toxicity of these four elements to the environment decreased. The risk of heavy metal release decreased from medium and high pollution levels to low pollution levels or even no pollution levels. For most metals, the fraction distributions were controlled by clay, silt, pH, and soil organic matter. The research methods and results can provide a theoretical and scientific basis for further study of wetland vegetation, and in addition, aid in selecting feasible restoration methods for further wetland restoration. [ABSTRACT FROM AUTHOR]

Wetlands play an important role in the global carbon cycle but are intensively disturbed by humans. Estimating the gaseous carbon budget of degraded wetlands has great significance for wetland conservation. The Shanyutan wetland is a degraded tidal wetland in Southeast China. We compared the landscape patterns of Shanyutan in 2009 and 2019 based on remote sensing images and determined the sediment CO 2 flux (excluding root respiration) in various land types. We combined the sediment CO 2 flux with the wetland CH 4 flux, and the CH 4 and CO 2 fluxes of aquaculture ponds, as well as net plant carbon sequestration (NPCS) from previous studies, and calculated the gaseous carbon budget of Shanyutan for the 10-year period. Our results show that the areas of aquaculture ponds and mudflats increased over the 10-year period, whereas those of vegetated marsh and sand decreased. Determination of the sediment CO 2 flux indicates that sediment CO 2 flux is higher in vegetated marsh and lower in bare land, with the highest annual flux in Spartina alterniflora marsh and the lowest in sand. The gaseous carbon budget shows that aquaculture ponds and bare land are sources of atmospheric carbon, whereas vegetated marsh serves as a sink. The entire wetland was an atmospheric carbon sink in 2009, with a carbon sequestration rate of 1364.4 tC·a−1; however, it became a source in 2019 due to destruction, with a carbon efflux of 1072.6 tC·a−1. Moreover, the gaseous carbon balance in Shanyutan had a climate-warming potential, with an equivalent CO 2 production of 5971.8 t·a−1 in 2009, and this potential increased ~9 times over the 10-year period. Finally, we conclude that restoring the carbon cycle of Shanyutan has considerable future economic value. [ABSTRACT FROM AUTHOR]

Disentangling the contributions of environmental gradients and spatial distance as species distribution drivers is a crucial topic of community ecology. Here, we sampled wetland plant communities at 779 plots from 52 sites and measured 12 key functional traits of 52 plant species in Poyang Lake, China. Using the generalized dissimilarity model (GDM), we examined which environmental variables and geographic distances best predicted the variations in community turnover (Simpson dissimilarity coefficients) at two spatial scales (i.e., plot and site) and compared the turnover patterns between species and functional approaches. We found that both species and functional turnover were typically higher at plot than site scale and that species turnover were higher than functional turnover across the studied scales. At plot scale, the GDM results showed that the best predictor of species turnover was elevation followed by soil moisture and geographic distance, while geographic distance was the best predictor at site scale. However, functional turnover was weak or showed no remarkable responses to either environmental variables or geographic distance. Notably, the communities showed a very high functional redundancy with slow shifts across the environmental gradients at both scales studied. This strongly suggests that most species were functionally redundant and that species replacement across environmental gradients and the two studied spatial scales is restricted to functionally identical species in the Poyang Lake wetland. Our results demonstrated that the coupling between plant species and functional turnover is reduced, which may allow the wetland plant community to maintain its ecosystem functioning when subjected to water level fluctuations. [ABSTRACT FROM AUTHOR]

Antibiotics are widely found in aquatic environments and pose a serious threat to natural habitats. Plants as an important part of constructed wetlands, phytoremediation is a potential way to purify antibiotic contaminated waters and soils and thus reduce the risk of antibiotic resistance. However, less is known about Response mechanism of typical wetland plants and removal of water pollutants under different levofloxacin concentration Therefore, this study evaluated the effects of the levofloxacin (LOFL) on chlorophyll and key enzyme activities among 8 typical wetland plants. At the same time, the removal of conventional water pollutants by different plant system treated with 0, 10, 1000 ug/L of LOFL was investigated. The results showed that the eight plants showed significant differences in the removal of contaminants as well as chlorophyll and key enzyme activities while the above indicators did not show obvious regularity due to the stress of antibiotics in the same type of plant. The removal rate of LOFL was 87.29-96.69% by plant system while only 0.26 to 5.89% was contributed by plant accumulation. Antibiotic contamination has potential impact on wetland plants and in practical applications, plants should be selected reasonably according to the target pollutants. • Different plants had significant differences in the removal rate of conventional pollutants. • Chlorophyll and key enzyme activities showed significant difference under the stress of LOFL. • The removal rate of levofloxacin contributed by plants was less than six percent. • Antibiotic contamination has potential impact on wetland plants. [ABSTRACT FROM AUTHOR]

Green stormwater infrastructure, such as constructed wetlands (CWs), is a type of stormwater control measure that can decrease nutrient and pollutant loads from urban stormwater runoff. Wetland soil microorganisms provide nutrient and pollutant removal benefits which can also result in ecosystem disservices such as greenhouse gas (GHG) emissions and can inadvertently exacerbate climate change. Microbial respiration by facultative anaerobes in anoxic conditions is the primary pathway for nitrogen removal (benefit). Similar anoxic conditions that support denitrifying microorganisms can also support obligate anaerobes that produce methane (CH 4) via methanogenesis (disservice). We examined nitrogen removal potential, GHG production, and microbial community structure within permanently flooded and shallow land or temporarily-flooded areas of a stormwater CW to identify zones for CW design optimization. Results indicate that permanently flooded zones compared to shallow land zones are greater sources of CH 4 emissions (80.80 ± 118.31, 2.32 ± 9.33 mg CH 4 -C m−2 h−1, respectively) and emit more carbon to the atmosphere (7161.27 kg CO 2 , 93.20 kg CO 2 equivalents, respectively). However, nitrogen removal potential rates were similar across both flooded and shallow land zones (24.45 ± 20.18, 20.29 ± 15.14 ng N 2 O-N hr−1 g−1 dry soil, respectively). At this particular CW, reduction of permanently flooded zones within the wetland could decrease GHG emissions (disservice) without limiting nitrogen removal (benefit) potential of the wetland. Holistic development and design of stormwater control measures, which account for microbial activity, provides the opportunity to maximize benefits (i.e., nutrient and pollutant removal) and reduce disservices (i.e., GHG emissions) of green stormwater infrastructure. Unlabelled Image • Microbial processes underlie trade-offs associated with SCM design features. • Holistic placement and design of SCMs can balance trade-offs. • Hydrology is a good determinant of CH 4 production (disservice). • Season best determines CO 2 production (disservice) and denitrification (benefit). • In urban CWs, increasing shallow land surface area could reduce CH 4 emissions. [ABSTRACT FROM AUTHOR]

Agricultural runoff is a major contributor of nutrients to downstream freshwater and marine waters that, in turn, cause harmful algal blooms. "Wetlaculture," a new landscape management approach defined as "integrating wetland nutrient removal with recycling of these nutrients to agriculture," has the dual goals of reducing the need for fertilizer in agriculture while mitigating fluxes of nutrients to downstream aquatic ecosystems with created or restored wetlands. A mesocosm compound consisted of twenty-eight 380 L, 1-m2 tubs filled with local hydric soil was initiated in mid-2016 near a highly eutrophic Buckeye Lake in central Ohio, USA, to investigate the wetlaculture approach in an experimental fashion. In October 2016, each mesocosm tub was inserted in the ground and planted with the sedge Schoenoplectus tabernaemontani. The mesocosms were assigned to four hydrologic treatments involving two water depths and two hydraulic loading rates (HLRs). Nearby river water containing significant agricultural runoff was added weekly into a water feed tank system to provide weekly hydraulic loadings to the mesocosms. Inflow and outflow water samples from each wetland mesocosm were collected and analyzed for five species of nitrogen and phosphorus. By August 2019, 17 plant species, including the planted S. tabernaemontani , were present in the wetland mesocosms. The wetland mesocosms soon became nutrient sinks with average removal efficiencies of total phosphorus (TP) and total nitrogen (TN) of 38 ± 2.5% and 44 ± 1%, respectively, through the three-year experiment. The combination of a high HLR (30 cm week−1) and 10 cm of standing water achieved the best nitrogen removal efficiencies while highest phosphorus removal occurred with the combination of a high HLR (30 cm week−1) and no standing water. This paper discusses the following integrative findings: • Seasonal flooding had positive impacts on removal efficiency of NOx and a negative impact on the removal efficiency of TP and TKN. • No standing water resulted in a higher removal efficiency of TP and TKN than standing water, results consistent with previous studies. • Macrophyte plant community richness was influenced more by water depth than by hydraulic loading rate. Wetlands with 10 cm of standing water instead of saturated soils developed lower species richness but were more dominated by true wetland (OBL and FACW) species. • Study scale does matter. Annual nutrient accumulation rates in the mesocosms (1 m2) soils were lower than in the full-scale (10,000-m2) multi-year wetlands at the nearby Olentangy River Wetland Research Park (ORWRP) in central Ohio. Annual accumulation rates of phosphorus and nitrogen in the full-scale wetlands ranged from 3.3 to 3.5 g-P m−2 yr−1 and 16.4 to 19.5 g-N m−2 yr−1, while in our mesocosms, the annual rates ranged from 0.66 to 1.40 g-P m−2 yr−1 and 7.85 to 15.08 g-N m−2 yr−1. Our experimental wetland mesocosms could only function in the non-freezing months and have been in operation for only three years. Unlabelled Image • Wetlaculture is designed to reduce fertilizer use and pollution of downstream lakes. • 28 bulrush mesocosms in Ohio reduced P and N by 38 and 44% respectively in 3 years. • High loading rates (30 cm week−1) achieved the best N and P removal. • Macrophyte richness was influenced more by water depth than by loading rate. [ABSTRACT FROM AUTHOR]

Urban, industrial, and agricultural development in river basins has resulted in the pollution of estuarine and coastal ecosystems with a great amount of organic microcontaminants (OMCs) such as pesticides and contaminants of emerging concern (CECs). This study takes the Ebro Delta as a case study to assess the increase or reduction of 25 OMCs in rice fields and one 86 ha constructed wetland (CW). Bentazone and MCPA were the most abundant pesticides in the rice-field drainage water, with a peak concentration of 21,318 and 938 ng/L respectively, whereas the greatest CEC concentrations were found for caffeine, benzotriazoles, and bisphenol A (20–71 ng/L, on average) in the rice irrigation water. Pesticide concentration increased after the irrigation water passed through the rice fields (from 102 to 1973 ng/L, on average), but CECs present in the irrigation water decreased by 37% (from 14 to 10 ng/L, on average). A mass balance study showed that the CW was capable of reducing OMCs by 67%. Risk assessment analysis showed that the cumulative hazard quotient for Daphnia magna , green algae, and fish was greater than 1 during several sampling campaigns for the rice-field drainage water, but the CW was capable of reducing it by 60–63%, resulting in values below 1, which indicates that the risk was not significant. The results thus indicate that rice fields reduce CECs, but increase pesticides, whereas the use of CWs seems to be a feasible nature-based solution to reduce the discharge of OMCs into estuarine and coastal areas. Unlabelled Image • Rice fields decreased contaminants of emerging concern by 37%. • Bentazone and MCPA were the most abundant pesticides in the rice-field drainage water. • The wetland reduced organic microcontaminants by 67%. • The wetland reduced the risk by 60–63%, resulting in values below 1. [ABSTRACT FROM AUTHOR]

Low-phosphorus (P) wetland discharges (e.g., < 20 μg/L), such as those now commonly observed in Stormwater Treatment Areas (STAs) for Everglades restoration, are likely influenced by internal P loads. This study estimated for the first time the "aggregated" internal P loading rate (iPLR) (including soil and biotic vectors) in a low-P treatment wetland along with calculated vertical soil diffusive fluxes. In situ mesocosms (1.5-m diameter polyethylene cylinders) equipped with closeable windows were deployed at three locations in an STA, enclosing parcels of local vegetation and soil. The mesocosms isolated the water column P response from longitudinal P transport (flow) so the local soil-water-biota P dynamics and equilibria could be observed during no-flow conditions. The water column inside and outside the mesocosms was sampled at each location during three two-week no-flow batch incubations. A first-order model was calibrated to mesocosm batch reaction time series to estimate the iPLR (with uncertainty) at each study site. Soil diffusive flux rates were estimated from vertical porewater P concentration profiles measured at each site. Results showed that: 1) strong gradients in water column equilibrium P concentrations existed along the direction of flow (92–20 μg/L from inflow to outflow), 2) a corresponding gradient also existed for model-predicted iPLR (~6.6 to 1.9 mg/m2-d), 3) these aggregated internal loads were more than 20× greater than calculated soil diffusive fluxes, and 4) an annual extrapolation suggested that average iPLR could be approximately equivalent to the average annual inflow P loading rate to the wetland (1.3 g/m2-yr). This study demonstrates that aggregated internal P loading can greatly exceed more commonly estimated vertical soil diffusive fluxes in low-P wetlands and can be a substantial contributor to water column P concentrations. Furthermore, measuring and modeling water P equilibria during no-flow intervals was a useful method to estimate internal loading in these wetlands. • Novel methods measured internal P loading rate (iPLR) in a treatment wetland. • iPLR magnitude was comparable to external P load. • Diffusion from soils contributed less than 5% of the iPLR. • Nutrient pumping by macrophytes is probable contributor to iPLR. • Insights offer opportunity to improve Everglades restoration projects. [ABSTRACT FROM AUTHOR]

Wetlands dominated by shrubs are ubiquitous features in the Great Lakes Region of North America, yet little is known about the interactions between plants and the environmental conditions of these ecosystems. We measured the response of seven common wetland shrub species and two forbs to soil moisture treatments over a growing season. Average soil moisture content across three treatments ranged from <30% to >75%. These soil moisture differences produced a measurable effect on plant growth for six of the nine species tested. While Rosa palustris and Spiraea alba preferred the highest soil moisture treatments, Salix interior , Sambucus nigra , and Solidago uliginosa had higher biomass from moderate soil moisture, with no effect observed for Cornus sericea , Salix discolor , and Viburnum lentago. Most of the growth differences were from aboveground portions of the plants. A significant difference in root-to-shoot ratio (R:S) was found for eight of the species, with contrasting directions of change between the soil moisture treatments. New growth was compared to mean stomatal conductivity to determine an estimated water use efficiency (WUEe), which demonstrated a montonal relationship for six of the species across the measured soil moisture regime. Only the upland goldenrod, Solidago altissima , demonstrated the expected increase in WUEe with decreasing soil moisture, which suggests wetland shrubs are inefficient at low soil moisture. The results of this study provide quantitative data on the range of responses to soil moisture of common species of shrub wetlands, which can be used by wetland managers to improve restoration success. • Thicket swamp species were grown in 3 soil moisture treatments for 1 growing season. • Soil moisture affected 8 of 9 species tested, mostly in aboveground shoots. • Species demonstrated a range of directional responses to increasing soil moisture. • Most wetland shrubs were inefficient users of water at low soil moisture. • Results provide guidelines for effective restoration shrub planting strategies. [ABSTRACT FROM AUTHOR]

Coppicing is a highly effective method of producing a great deal of fast growing, sustainable timber without the need for replanting. Tamarix chinensis , a native salt-tolerant species, plays an important role in the ecosystems of arid saline alkali soil and coastal wetlands in northern China. In this study, we conducted a coppicing field experiment on T. chinensis to study the vigor of resprouting over a 4-year monitoring period in the coastal wetland of Laizhou Bay, China. Results of this study show that the growth of coppiced T. chinensis was vigorous and conformed to an "S-curve" type growth pattern. The height and crown of coppiced T. chinensis recovered quickly to the initial level by the 2nd year of regrowth and its aboveground biomass regained 93.5% of the previous level by the 4th year. The carbon stock in the T. chinensis wetland was significantly increased by the coppicing operation. Carbon stocks in the aboveground parts and soil (0–100 cm) increased by 222.6 g m−2 and 588.9 g m−2, respectively, during the 4-year experimental period. These values are 43% and 74% higher, respectively, than those in the control plot over the same period. These results indicate that coppicing provides a practical means for promoting regeneration and rejuvenation of Tamarix spp. forests as well as a new approach to increasing biomass and carbon stocks in the coastal wetlands of northern China. [ABSTRACT FROM AUTHOR]

Soil active organic carbon responds quickly to soil disturbances and is a sensitive indicator of early changes in soil organic carbon (SOC). In order to identify the differences in the distribution of dissolved organic carbon (DOC), light fraction organic carbon (LFOC), SOC and their changes as affected by vegetation degradation degree along water gradient in wetland, we analyzed DOC, LFOC, and SOC in the 0–100 cm soil layer under four vegetation degradation degrees: non-degradation (ND), lightly degradation (LD), moderately degradation (MD) and heavily degradation (HD). The results showed that soil DOC, LFOC and SOC in the 0–100 cm layer of ND wetland was significantly higher than the other three degradation levels. DOC, LFOC and SOC contents decreased with increasing soil depth under the four degradation degrees and the contents of soil DOC, LFOC and SOC were mainly concentrated in the soil surface (0–20 cm). The DOC, LFOC, and SOC contents in the 0–20 cm layer under all four degradation levels showed obvious seasonal changes, while the DOC, LFOC, and SOC contents in the 20–100 cm layer showed little fluctuation over the plant growing season. There was a significant positive correlation between soil DOC and SOC, and between LFOC and SOC, with correlation coefficients of 0.948 and 0.911, respectively. There was also a very significant correlation between DOC and LFOC(R2 = 0.904). Soil DOC and LFOC in the 0–100 cm layer under the four degree of degradation were linearly correlated with SOC. While there was a linear correlation between DOC and LFOC in the non-degradation wetland soils, DOC and LFOC in the three degradation soils correlated exponentially correlated with SOC. • Vegetation degradation leads to sharp reduction in SOC, LFOC, and DOC. • Results have important implications for assessing impacts of management changes and climate change on wetland soil quality and productivity. [ABSTRACT FROM AUTHOR]

The aim of our research was to estimate the amount of energy, C, N and P that potentially could be extracted from the plant biomass harvested annually in the Narew National Park (NE Poland). We found that the conversion of biomass through anaerobic digestion (AD) delivers not only power and heat but also ensures the recovery of nutrients and organic matter for their reuse in agriculture. The most productive community with the highest biomass yield was reed bed of Phragmites australis (9.78 ± 1.66 t d.w. ha−1). It was followed by Phalaridetum and tall sedge communities with Carex elata and C. gracilis (6–7 t d.w. ha−1), rushes of Glyceria maxima (3.61 ± 0.63 t d.w. ha−1), and sedge moss communities with C. lasiocarpa (~1 t d.w. ha−1). Annual vegetation management would result in ~33·103 t d.w. of biomass. The primary net energy output was related to the productivity of the vegetation and ranged from ~17 GJ ha−1 for the sedge moss communities to 160 GJ ha−1 for Phragmitetum australis. The methane potential of the studied species was low and varied between 89 Nm3 t−1 d.w. for Phragmites and 188 NL kg−1 d.w. for Glyceria maxima. Consequently, the unit related net gain of energy in CH 4 ranged between 23 and 30 GJ ha−1 for the perennial grasses and tall-sedge communities, and 3.5 GJ ha−1 for the low-productivity sedge-moss communities. As a result of low energy inputs for harvesting, the wetland biomass exhibited a favorable energy balance. The annual potential of CH 4 for the whole studied valley section was 3286 ± 439·103 m3 resulting in net electricity potential of ~9.1 GWh and waste heat –32.3 TJ. An "average" hectare of wetland could power 1.2 household and provide 1010.4 ± 169.4 kg of C, 117.8 ± 19.6 kg of N, and 11.9 ± 2.0 of P applied do crop soils along with a digestate. • Conversion of wetland biomass through anaerobic digestion delivers energy and recovers nutrients for agriculture. • A hectare of marsh could power 1.2 households and provide 1010±169 kg of C, 118±20 kg of N, and 12±2 of P. • The wise use of fluviogenous wetlands can empower local economy and introduce a circularity into managing bioresources. [ABSTRACT FROM AUTHOR]