Search Results (26)

Clarifying carbon (C), nitrogen (N), and phosphorus (P) ecological stoichiometry helps us to understand the ecological functions of wetland ecosystems. This study investigated the variations in ecological stoichiometry and their driving factors in the Yellow River wetland. Soil and plant samples were collected and analyzed from riparian lower-beach wetland (LBW), riparian higher-beach wetland (HBW), and depressional wetland (DW) at the junction of the middle and lower reaches of the Yellow River, respectively. Compared with HBW, DW exhibited higher soil C/N (9.15 ± 0.13), C/P (11.17 ± 0.52), and N/P (1.08 ± 0.09) (p < 0.01), indicating its stronger C and N storage capacity. At the community level, higher plant C/N and C/P in LBW (21.47 ± 1.61 and 206.80 ± 1.75, respectively) and HBW (22.91 ± 0.90 and 241.04 ± 3.28, respectively) compared to DW (14.44 ± 1.02 and 115.66 ± 2.82, respectively) (p < 0.01) suggested that plants in LBW and HBW had greater C assimilation and nutrient use efficiency. Soil electrical conductivity (EC) and hydrolyzed N (SHN) positively affected soil ecological stoichiometry (p < 0.01). In contrast, soil EC, soil organic C, dissolved organic C, and SHN negatively altered plant stoichiometric ratios (p < 0.05), which were regulated by plant functional groups. When pooling all wetlands, stoichiometric ratios of plants were closely correlated with those of soil (p < 0.05). These findings demonstrate that wetland types notably affect soil and plant stoichiometry. Wetland types exerted opposite effects on soil and plant stoichiometry due to the different influences of soil physicochemical properties and the coupling effects of nutrient and stoichiometry between soil and plants. Therefore, the interactions between plant and soil stoichiometry should be considered to explore the C and nutrient cycles in riverine wetlands. Our research emphasizes the necessity of considering wetland type differences and intricate plant–soil stoichiometric interactions in formulating management strategies and maintaining the sustainability of wetlands. Full article

The present study is based on the characterisation of adobe blocks of the central region of Portugal. It is recognised that the safeguarding of the existing building stock of constructions in the traditional adobe construction technique, through different levels interventions, should also preserve the historical and cultural identity of the area as well as the traditional construction techniques, starting from the ground itself. Soil, as a repository of valuable information on the history of the site, underpins the conservation and preservation process. However, the soil is a local expression of the site, and a precise knowledge of its characteristics is necessary to hypothesise building recovery strategies. For this reason, the characteristics of adobe blocks from old buildings in the village of Torres in Anadia, in a rural area that has not yet been the subject of scientific research, were evaluated. These adobe blocks were taken from the buildings to be used in the laboratory to determine the similar mixing rates for the new adobe mixtures by analysing the material’s chemical, physical, mechanical, and thermal properties, as well as its particle size distribution. In the study area, a wetland was identified characterised by a notable presence of vegetation, namely bunho and junco (Schoenoplectus lacustris L.). These fibres, which can be assimilated to Typha, are wild aquatic plants that can impair the biodiversity of wetlands but which, used as reinforcement for the production of adobe bricks, can stimulate new, more sustainable forms of economy in in the area, which is classified as rural. The fibres were divided into two groups of 10–30 mm and 30–60 mm in length, and compositions with an additional 1 to 3% of fibres were formulated. This experimental approach was useful for understanding how the length and quantity of these fibres influence the performance of the material, thus contributing to improving knowledge about the behaviour of adobe blocks in relation to the incorporation of vegetable fibre reinforcement. The research findings reveal that the length of the fibres and percentage of incorporation have a significant impact on the mechanical behavior of the material, particularly in relation to its compressive strength up to 50%. The tested formulations were also assessed with respect to capillarity, for which most of the formulations were classified as weakly capillary, with a capillary index (Cb) of less than 20. With respect to thermal conductivity, the incorporation of fibres led to a reduction of up to 20%. The characterisations demonstrate that the optimisation of adobe is the initial stage in attaining comprehensive insight into the heritage of traditional construction in the central region of Portugal, with a particular focus on the village of Torres and the ancient adobe construction technique. Full article

This study designed integrated constructed wetland–microbial fuel cell (CW–MFC) systems using activated carbon (AC) as both CW substrates and MFC anodes and investigated the structure-activity relationship of six kinds of commercial columnar AC, as well as the organics and nitrogen removal, microbial activity and diversity of CW–MFCs. Results showed that the nitrogen adsorption by AC tended to be a linear process in which physical adsorption played a leading role and micropores made great contributions. A higher specific surface area, developed mesopores, and oxygen functionalities were conducive to the capacitance properties of AC, while a higher specific surface area and developed micropores were conducive to reduce material resistance and improve ion permeability. Coconut-shell-based AC had both excellent nitrogen adsorption capacity and electrochemical properties, making it ideal as both CW substrates and MFC anodes for CW–MFCs. The electricity generation, coulombic efficiency, internal resistance, and organics and nitrogen removal of CW–MFCs were positively correlated with the total depth of AC anodes. The total depth of AC anodes can be determined based on the influent organics/nitrogen loadings and organics/nitrogen removal load of AC, and a relatively smaller depth of a single AC anode (5 cm) was recommended. The MFC effectively improved the enzymatic activity (by 10.33% dehydrogenase, 8.72% catalase, and 7.35% ammonia monooxygenase), nitrification/denitrification intensity (by 9.53%/6.68%), and microbial diversity (by 1.64–4.07%) of AC (MFC anodes) in CW–MFCs, while the depth of a single AC anode barely influenced the microbial activity and diversity. MFCs increased COD and NH₃-N removal in CW–MFCs by 11.60% and 3.4%, respectively. The increased total adsorption capacity of AC with the increase of its total depth narrowed the difference in COD removal resulting from the promotion of MFCs on organics degradation. MFCs increased TN removal in CW–MFCs by 5.29% through promoting denitrification in cathodes and enhancing NH₃-N assimilation in anodes. The phyla of EAB (Proteobacteria, Bacteroidetes, Firmicutes, and Acidobacteria) and genera of EAB (Citrobacter, Geobacter, and Pseudomonas) accounted for 85–86% and 15.58–16.64% of the microbial community on AC anodes in CW–MFCs, respectively. Full article

Soil microbial ecology in the Irish wetlands is still poorly understood, although it is crucial in introducing effective rewetting schemes to restore and conserve the Irish peatlands. As an initiative, peatlands with distinct land-use types (cutaway, raised semi-degraded, unimproved grassland and grassland) were collected from farms in the midlands to analyse various microbial populations. Peat was homogenized and serially diluted to culture on a range of specific and non-specific culture media. Culture isolation and microbial enumeration were performed. Gram staining and other microscopic observations of morphologically distinct microorganisms were performed, followed by isolation procedures. The numbers of total viable bacteria of cutaway bog and unimproved grassland were 4.23 × 10³ CFU g⁻¹ and 9.81 × 10⁷ CFU g⁻¹, respectively, with a significant statistical difference (p ≤ 0.05). Raised semi-degraded bogs comprised low values of both aerobes and fungal populations. Penicillium spp. and Trichoderma spp. were common in many vegetation types. Phosphate-solubilizing bacteria were present in the majority of the study sites. This indicated that the soluble form of phosphorus was being assimilated by plants. Cutaway peat contained the bacteria with the highest phosphate-solubilizing index (3.167). Overall, the number of culturable microbial groups in cutaway and raised semi-degraded peatlands exhibited significant differences, while the rest did not show drastic changes according to land-use type. This study provides baseline data to continue studies on bog microbiology, which provides a new outlook for restoration. Future work should consider microbial interaction with environmental variables in different land-use types. Full article

Coastal Louisiana is currently experiencing high rates of wetland loss and large-scale ecosystem restoration is being implemented. One of the largest and most novel restoration projects is a controlled sediment diversion, proposed to rebuild and sustain wetlands by diverting sediment- and nutrient-rich water from the Mississippi River. However, the impact of this proposed sediment diversion on the nutrient budget of the receiving basin is largely unknown. A water quality model was developed to investigate the impact of the planned Mid-Barataria Sediment Diversion on the nutrient budget of the Barataria Basin (herein referred to as ‘the Basin’). The model results indicate that the planned diversion will increase TN and TP pools by about 38% and 17%, respectively, even with TN and TP loadings that increase by >300%. Water quality model results suggest that the increase of nutrients in the basin will be mitigated by increased advection transport (i.e., decreased residence time from ~170 days to ~40 days, leading to greater flushing) and increased removal via assimilation, denitrification, and settling within the Basin. Advection transport resulted in higher TN removal in the Basin than other processes, such as uptake or denitrification. Approximately 25% of the additional TN loading and 30% of the additional TP loading were processed within the Basin through the assimilation of phytoplankton and wetland vegetation, denitrification, and burial in the sediment/soils. These nutrient budgets help to better understand how the planned large-scale sediment diversion project may change the future ecological conditions within the estuaries of coastal Louisiana and near-shore northern Gulf of Mexico. Full article

The management of reverse osmosis concentrate (ROC) poses a challenge to utilities as it requires expensive disposal methods and advanced treatment in order to comply with regulations. This paper presents studies of natural treatment approaches, such as constructed wetlands (CWs), that have been tailored to treat ROC. Conceptually, with testing and planning, these wetlands could meet regulatory criteria before discharging to the surface water and achieving multiple benefits. Lessons learned from pilot studies of wetland treatment of ROC point to the potential benefits of designing full-scale wetlands for concentrate management. Studies have illustrated the ability of CWs to reduce the concentrations of metals and simultaneously remove nutrients to meet state standards for aquatic and wildlife designated uses. Nutrient removal processes include denitrification for nitrogen removal (possibly supplemented with Annamox reduction of NO₃-N), labile carbon assimilation supporting oxidized nitrogen reduction, and phosphate-P uptake and precipitation. Because of the evaporative water loss, mass removal efficiencies were greater than concentration reductions. Studies illustrate how engineered wetlands help with the management of ROC produced from reclaimed water through reductions in concentration and volume for disposal through evapotranspiration. The associated creation of wildlife habitats and coastal wetland restoration could result in the renewal of multiple ecosystem services. Full article

Recent advances in satellite observations of methane provide increased opportunities for inverse modeling. However, challenges exist in the satellite observation optimization and retrievals for high latitudes. In this study, we examine possibilities and challenges in the use of the total column averaged dry-air mole fractions of methane (${\mathrm{XCH}}_4$) data over land from the TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinel 5 Precursor satellite in the estimation of ${\mathrm{CH}}_4$ fluxes using the CarbonTracker Europe-${\mathrm{CH}}_4$ (CTE-${\mathrm{CH}}_4$) atmospheric inverse model. We carry out simulations assimilating two retrieval products: Netherlands Institute for Space Research’s (SRON) operational and University of Bremen’s Weighting Function Modified Differential Optical Absorption Spectroscopy (WFM-DOAS). For comparison, we also carry out a simulation assimilating the ground-based surface data. Our results show smaller regional emissions in the TROPOMI inversions compared to the prior and surface inversion, although they are roughly within the range of the previous studies. The wetland emissions in summer and anthropogenic emissions in spring are lesser. The inversion results based on the two satellite datasets show many similarities in terms of spatial distribution and time series but also clear differences, especially in Canada, where ${\mathrm{CH}}_4$ emission maximum is later, when the SRON’s operational data are assimilated. The TROPOMI inversions show higher ${\mathrm{CH}}_4$ emissions from oil and gas production and coal mining from Russia and Kazakhstan. The location of hotspots in the TROPOMI inversions did not change compared to the prior, but all inversions indicated spatially more homogeneous high wetland emissions in northern Fennoscandia. In addition, we find that the regional monthly wetland emissions in the TROPOMI inversions do not correlate with the anthropogenic emissions as strongly as those in the surface inversion. The uncertainty estimates in the TROPOMI inversions are more homogeneous in space, and the regional uncertainties are comparable to the surface inversion. This indicates the potential of the TROPOMI data to better separately estimate wetland and anthropogenic emissions, as well as constrain spatial distributions. This study emphasizes the importance of quantifying and taking into account the model and retrieval uncertainties in regional levels in order to improve and derive more robust emission estimates. Full article

Studying the CO₂-assimilation potential under the effect of glucose addition is of great significance to completely comprehend the dynamic carbon cycle in wetland ecosystems. Rhizospheric sediments (RS) and bulk sediments (BS) were selected, with the addition of glucose (G) or not, and two experimental pots (RSG and BSG) and two control pots (RS and BS) were formed. Then, within 45 h of glucose addition, the sediments were sampled at intervals of 4 h for dynamic monitoring. The bacterial communities encoded by CO₂-assimilating function genes (cbbL) and the corresponding activities of key enzyme (ribulose-1,5-bisphosphate carboxylase oxygenase, RubisCO), and the light fraction (LF) and heavy fraction (HF) of organic carbon (C) and nitrogen (N) of the samples were determined. The results demonstrated that the dynamic processes of glucose deposition and degradation occurred in sediments from RSG and BSG, with the greatest depositions of 2.35 and 2.48 mg·g⁻¹ in the 4th and 12th hour, respectively. The contents of LFOC, LFON, HFOC, and HFON decreased by 171.70%, 125.45%, 8.40%, and 68.17% in the RSG pot, and decreased by 221.55%, 102.61%, 0.07%, and 74.74% in the BSG pot, respectively, which suggested the dominant activities of C and N mineralization. The FT-MIR of LF showed different changes of typical chemical bonds between RSG and BSG during the process, which further indicated irregular and inconsistent mineralization activities. The RubisCO activities in the rhizospheric sediments (52.14 nmol (g·min)⁻¹ on average) were substantially greater than in the bulk sediments, which indicated the high potential of carbon assimilation in rhizospheric sediments. Moreover, it showed a lower trend in BSG, BS, and RS, but an increasing trend in RSG after the glucose addition, albeit the effects were recovered in the 45th hour. The cbbL-containing bacteria were more abundant in the rhizospheric sediments than in the bulk sediments, and this effect was higher than that of the glucose addition. Proteobacteria were the dominating phylum with mean values of 93.49%, and Burkholderiales was found to be the dominant order (37.74% on average). Moreover, the changes in bacterial composition between the rhizospheric sediments and bulk sediments were more pronounced than they were during the process. Therefore, the effects of glucose degradation on RubisCO activity and cbbL-containing bacteria were transient, but the effects on organic matter fractions were straightforward, which probably further change the bacterial abundance and composition. Full article

Due to its low C/N ratio and high concentrations of nitrogen and phosphorus, the effluent of anaerobic cyanobacteria fermentation cannot be directly discharged without further treatment. To effectively reduce nutrient loads and utilize the nutrient resources of biogas slurry generated from the anaerobic digestion of stored algae, two different aerobic treatment units (AUs) were combined with an ecological treatment unit (EU) to create two different treatment systems. The two AUEU systems paired a constructed wetland (CW) with either a cascade biological contact reactor (CBCR) or a carrousel oxidation ditch reactor (CODR). In this paper, the water quality characteristics of biogas slurry were measured, and comprehensive experiments on the two trial-treatment systems were carried out to validate their performance in removing pollutants and utilizing resources. Furthermore, the pollutant removal efficiencies of the combined systems, along with the removal mechanisms and utilization of the nitrogen and phosphorus in the CWs, were also investigated. The results showed that the CWs, with aquatic vegetation, took up the majority of removed nitrogen and phosphorus by absorption, which effectively reduced the concentration of pollutants in the effluent and enabled the nitrogen and phosphorus to be reused in plants. Biomass assimilation by the absorption by vegetation took up 75.8%, 66.1%, 70.3%, and 86% of the removed NH₄⁺-N, NO_x⁻-N, TN, and TP, respectively. Full article

Soil moisture impacts the biosphere–atmosphere exchange of CO₂ and CH₄ and plays an important role in the terrestrial carbon cycle. A better representation of soil moisture would improve coupled carbon–water dynamics in terrestrial ecosystem models and could potentially improve model estimates of large-scale carbon fluxes and climate feedbacks. Here, we investigate using soil moisture observations from the Soil Moisture Active Passive (SMAP) satellite mission to inform simulated carbon fluxes in the global terrestrial ecosystem model LPJ-wsl. Results suggest that the direct insertion of SMAP reduces the bias in simulated soil moisture at in situ measurement sites by 40%, with a greater improvement at temperate sites. A wavelet analysis between the model and measurements from 26 FLUXNET sites suggests that the assimilated run modestly reduces the bias of simulated carbon fluxes for boreal and subtropical sites at 1–2-month time scales. At regional scales, SMAP soil moisture can improve the estimated responses of CO₂ and CH₄ fluxes to extreme events such as the 2018 European drought and the 2019 rainfall event in the Sudd (Southern Sudan) wetlands. The simulated improvements to land–surface carbon fluxes using the direct insertion of SMAP are shown across a variety of timescales, which suggests the potential of SMAP soil moisture in improving the model representation of carbon–water coupling. Full article

In this study, a novel crude oil degrading bacterium was isolated from an oil-contaminated freshwater lake using crude oil as the sole carbon source. The strain was named Pseudomonas aeruginosa AQNU-1 based on the analyses of its morphological characteristics and 16S rRNA gene sequencing. Gas chromatography-mass spectrometry (GC-MS) was carried out to investigate the degradation of crude oil fractions under dynamic (37 °C, 180 r/min) and static (37 °C, 0 r/min) cultivation over three months of continuous enrichment in the laboratory. It was found that strain AQNU-1 exhibited stronger biodegradation efficiency for n-alkanes of C13–C35 under dynamic cultivation with degradation ratios of 87–100% compared to ratios of 74–100% under static cultivation. Furthermore, this strain could fully utilize alkylcyclohexane (M/Z 82), alkylbenzene (M/Z 92) and alkyltoluene (M/Z 106) in crude oil under both conditions. It also had better biodegradability of partial aromatic compounds in the crude oil, showing differences within compound families of aromatic hydrocarbons. Further, the potential degradation ability of this isolated strain decreased with increasing molecular weight, with the dynamic condition performing better in general. These results suggest that the isolated strain has great potential to assimilate indigestible crude-oil contaminants under different hydrological conditions, providing a valuable microbiological resource for in situ remediation of natural wetlands. Full article

The acquisition of Antibiotic-Resistance Genes (ARGs) by natural bacteria caused by antibiotic abuse is causing serious problems for human and animal welfare. Here, we evaluated the influence of three cladoceran species on Antibiotic-Resistant Bacteria (ARB) and tetracycline-resistance gene (tet(A)) copies, and discussed the effect of these biological interactions on the distribution and diffusion of ARGs in freshwater ecosystems. Bacterial community and tet(A) abundances in water samples collected from wetlands were strongly influenced by cladoceran presence. The presence of Daphnia obtusa dramatically decreased ARB and tet(A) abundance compared to that with other cladoceran species (Chydorus sphaericus and Simocephalus vetulus). Interestingly, we found a high abundance of Flavobacteriales in the microbiomes of cladoceran species. Considering that Flavobacteriales species are potential carriers of the tet(A) gene, their adsorption and assimilation with cladocerans could significantly impact the reduction of tet(A) in water. Field surveys also showed that tet(A) abundance could be low if the dominance of D. obtusa in each wetland was high. This study highlighted the need for ecological interactions and a broad range of niches in the food web when discussing the fate of ARGs in freshwater ecosystems. Full article

Impacts on wetlands are becoming more pressing every day. Among them, habitat loss, overexploitation of aquifers and changes in land use are considered the most important. However, the impacts linked to wastewater discharges are increasing worldwide. In this context, this study analyses the impacts of input of wastewater to a Mediterranean Ramsar temporary wetland (Fuente de Piedra, south of Spain). To this end, systematic sampling was carried out in the Charcón stream which receives water from a wastewater treatment plant (WWTP) and discharges it into the wetland. The results showed a slight decrease in the nutrient concentrations, particularly for nitrogen compounds. Heterotrophic and fecal bacteria concentration, as well as phytoplankton and zooplankton abundance and biomass, all significantly decreased from the treatment plant to the wetland. When comparing the effect of this discharge with other similar occurring to the same wetland, it was evident that the Charcón stream was responsible for a greater impact. At this point, it is relevant to note that the main difference among both treated wastewater discharges lies in the different water retention time once the wastewater was released from the WWTP. In fact, we recommend an increase in the water retention time by building seminatural ponds, together with the use of biofilters, which will notably contribute to improve the processes of assimilation of nutrients and to decrease the impact generated in the wetland by this spill. Full article

In arid desert areas, Haloxylon ammodendron plays an important role in maintaining the ecological balance of desert oases. However, there are few studies on the physiological characteristics of Haloxylon ammodendron under an environmental gradient. Here, we studied the changes in the morphological and photosynthetic characteristics and their correlations in Haloxylon ammodendron in the four habitats of the Ebinur Lake wetland. Our results show that in high-water and high-salt habitats, photosynthesis is affected by “stomata restriction,” while in other habitats, photosynthesis is mainly affected by “non-stomata restriction.” In addition, when the soil conditions were good, Haloxylon ammodendron chose leaf construction featuring high specific leaf area, while when the soil conditions were worse, it chose an opposite leaf construction model to ensure the optimal allocation of carbon assimilation products in heterogeneous habitats. This study will deepen our understanding of the trade-off strategy between the accumulation and distribution of plant photosynthate in special habitats in arid areas. The results are of theoretical value for analysis of the ecological adaptation mechanisms of plants in arid desert areas. Full article

Lake Cerknica is an intermittent wetland ecosystem with extreme water level fluctuations. It hosts extensive reed stands that have colonized different habitat types. Two different stands were compared: a lake stand not directly influenced by the intermittent River Stržen and a riparian stand near River Stržen. Reed productivity (growth and assimilate allocation) was monitored for these reed stand types over 13 years (2007–2019), and this measurement was compared to monthly water levels and air temperatures. Reeds from the lake reed stand were significantly shorter with a lower shoot density, overall biomass production, and ratio of flowering plants. A correlation analysis revealed stronger and more numerous significant correlations between environmental and reed productivity parameters for the lake reed stand compared to the riparian reed stand. The variabilities of the growth and assimilate allocation parameters in the lake reed stand were both mostly explained by the combined water levels for June and July, which explained 47% and 52% of the variability, respectively. The most influential temperatures were in May, which explained 29% and 19% of the variability of growth and assimilate allocation parameters, respectively. For the riparian reed stand, water levels and temperatures out of the vegetation season appeared more important. Therefore, habitats with permanent water are more suitable for reeds than those with fluctuating water. However, fluctuating water conditions are expected to become more common due to climate change. Full article