Natural Wetlands Research Articles

Effects of urban land change on ecosystem service values in the Bolgoda Wetland, Sri Lanka

Understanding the effect of urbanization on urban wetland ecosystem service value (ESV) can provide scientifically sound information for urban planning and the protection of urban wetlands. This study aimed to discuss the effect of urbanization on the Bolgoda wetland, located in the Colombo Metropolitan Region (CMR), Sri Lanka. We developed a framework to evaluate the ESV changes based on land use/cover (LUC) changes between 1989 and 2021. Considering Natural Growth (NG) and Wetland Protection (WP) scenarios, we projected the future LUC changes (2030 and 2050) and evaluated the future ESV changes. The results revealed that the ESV has declined by USD 116 million/year from 1989 to 2021. The scenario analysis indicated that the ESV will continue to decrease by USD 17 million/year in 2030 and USD 35 million/year in 2050 under the NG scenario. However, under the WP scenario, the decrease would only be about USD 0.96 million/year in 2030 and USD 11 million/year in 2050, respectively. The most important ecosystem service functions are water regulation, genetic resources, food production, and climate regulation. Therefore, the local government should practice wetland management strategies to enhance the ESV of the Bolgoda wetland and other urban wetland ecosystems (UWEs) in the country.

Simulation of the Impacts of Sea-Level Rise on Coastal Ecosystems in Benin Using a Combined Approach of Machine Learning and the Sea Level Affecting Marshes Model

Sea-level rise in Benin coastal zones leads to risks of erosion and flooding, which have significant consequences on the socio-economic life of the local population. In this paper, erosion, flood risk, and greenhouse gas sequestration resulting from sea-level rise in the coastal zone of the Benin coast were assessed with the Sea Level Affecting Marshes Model (SLAMM) using ArcGIS Pro 3.1 tools. The input features used were the Digital Elevation Map (DEM), the National Wetland Inventory (NWI) categories, and the slope of each cell. National Wetland Inventory (NWI) categories were then created using Support Vector Machines (SVMs), a supervised machine learning technique. The research simulated the effects of a 1.468 m sea-level rise in the study area from 2021 to 2090, considering wetland types, marsh accretion, wave erosion, and surface elevation changes. The largest land cover increases were observed in Estuarine Open Water and Open Ocean, expanding by approximately 106.2 hectares across different sea-level rise scenarios (RCP 8.5_Upper Limit). These gains were counterbalanced by losses of approximately 106.2 hectares in Inland Open Water, Ocean Beaches, Mangroves, Regularly Flooded Marsh, Swamp, Undeveloped, and Developed Dryland. Notably, Estuarine Open Water (97.7 hectares) and Open Ocean (8.5 hectares) experienced the most significant expansion, indicating submergence and saltwater intrusion by 2090 due to sea-level rise. The largest reductions occurred in less tidally influenced categories like Inland Open Water (−81.4 hectares), Ocean Beach (−7.9 hectares), Swamp (−5.1 hectares), Regularly Flooded Marsh (−4.6 hectares), and Undeveloped Dryland (−2.9 hectares). As the sea-level rises by 1.468 m, these categories are expected to be notably diminished, with Estuarine Open Water and Open Ocean becoming dominant. Erosion and flooding in the coastal zone are projected to have severe adverse impacts, including a gradual decline in greenhouse gas sequestration capacity. The outputs of this research will aid coastal management organizations in evaluating the consequences of sea-level rise and identifying areas with high mitigation requirements.

Fine-scale spatial genetic structure and dispersal among Italian smooth newt populations in a rural landscape

Amphibians are particularly sensitive to habitat loss and fragmentation caused by the intensification and modernization of farming occurring in the second half of the twentieth century in the Mediterranean basin. However, artificial water bodies, associated with traditional husbandry, proved to be important surrogate for amphibian feeding and reproduction. Here, multilocus genotypes were used to investigate the spatial population structure of Lissotriton vulgaris meridionalis and the role of drinking troughs in supporting viable breeding populations within a rural landscape interested by traditional husbandry and agriculture. Our genetic analysis highlighted the conservation value and the potential stepping-stone function of artificial aquatic sites in the dispersal of the species and for the gene flow maintenance. Indeed, populations of drinking troughs show allelic richness and heterozygosity levels comparable to those from natural ponds and there is no great evidence of genetic bottlenecks. A complex system of artificial aquatic sites and few natural wetlands was identified sustaining a well-structured network of demes highly interconnected with themselves and natural aquatic sites. The conservation of the identified genetic clusters may be useful to prevent further population declines and future loss of genetic diversity within the study area characterized by scarce natural wetlands that frequently dried because of agricultural practices and strong seasonality. Site-specific protection measures are needed to contrast the progressive disappearance of drinking troughs observed in the last years in Italy because of the abandonment of traditional farming practices in favour of modern agriculture and intensive farming.

Novel insight into the aging process of microplastics: An in-situ study in coastal wetlands

Coastal wetlands, the critical interface between the terrestrial and marine environments, provide a dynamic and unique environment for the aging of microplastics (MPs). Nevertheless, both abiotic and biotic processes that contribute to the aging of MPs in coastal wetlands have been largely neglected. In this study, the aging of MPs was continuously characterized in Hangzhou Bay, a representative coastal wetland in Zhejiang, China. Three-month exposure of polymers in sediment-water interface induced the aging phenomenon with embrittlement and exfoliation, as evidenced by simultaneous observed alternations in crystallinity and functional groups. A first-order kinetic model was fitted to describe the rate and degree of aging quantitatively. As evidenced by the carbonyl index, the residence time of all the examined MPs exhibited significant variance, ranging from 335 to 661 days. These variations might be caused by the selective attachment of plastic-degrading microorganisms (such as Moraxella sp. and Rhodococcus sp.). A positive correlation between the carbonyl index, the number of OTUs in the MP-associated biofilm, and irradiation was observed (p < 0.001), suggesting that the aging process may be co-regulated by natural sunlight and wetland microbial colonization. This study sheds new light on the long-term environmental fate of MPs and their associated ecological risks.

Paddy cultivation in degraded karst wetland soil can significantly improve the physiological and ecological functions of carbon-fixing resident microorganisms

Microorganisms play an important role in carbon fixation in karst wetland soils. However, the carbon fixation capacity of karst wetland soils and active microorganisms involved in the carbon fixation process are poorly understood. In this study, carbon fixation capacity and active microorganisms involved in the fixation of inorganic carbon into organic carbon were studied in native, naturally degraded, and reclaimed karst wetland soils by the combination of stable isotope probing (SIP) and high-throughput sequencing. Under light conditions, the soil carbon fixation capacity ranked: the reclaimed wetland soil (1.58 mg C kg−1 day−1) > native wetland soil (1.43 mg C kg−1 day−1) > degraded wetland soil (0.62 mg C kg−1 day−1). In the dark, the soils ranked: the native wetland soil (0.24 mg C kg−1 day−1) > reclaimed wetland soil (0.18 mg C kg−1 day−1) > degraded wetland soil (0.06 mg C kg−1 day−1). Active microorganisms fixing inorganic carbon in the karst wetland soils were mainly Sulfurovum, Thermovirga, Dethiosulfatibacter, Allochromatium, Methylorubrum, and Bradyrhizobium. Thus, paddy cultivation can restore the carbon fixation capacity of microorganisms in the degraded karst wetland soil. This study provides an experimental basis for improving soil carbon fixation capacity and repairing degraded soil in karst wetlands.

Modelling faecal microbe dynamics within stormwater constructed wetlands

Modelling faecal microbe levels is performed widely in natural and wastewater wetlands, yet these predictions can be challening due to highly stochastic storm events. In our study, a coupled hydrodynamic and microorganism model was developed and tested to predict the long-term faecal microbial removal in stormwater constructed wetlands. The microorganism model simulates the fate and transport of the faecal indicator organism Escherichia coli (E. coli), resolving advection-dispersion, sedimentation, resuspension and die-off based on temperature and UV exposure. The model was tested using a two-year monitoring dataset collected from Troups Creek wetland, a multiple-inflow stormwater wetland in Melbourne, Australia. The model parameter values applied in the coupled model were based on a mixture of site-specific data and values obtained from literature. The only adjusted parameter in our microorganism model was the die-off rate in dark conditions in the stormwater wetlands. An urban stormwater microorganism model, MOPUS, was used to generate continuous catchment E. coli loading rates as input to the wetland. The hydrodynamic model was evaluated using flow rate monitored at the outlet weir, achieving Nash- Sutcliffe Efficiency (E) values of 0.86 over the two-year monitoring period. The E. coli model was tested using outflow E. coli concentration data and achieved an overall E of 0.37. The performance of the microbial model was variable across the 22 monitored events, with E ranging from <0 to 0.8. Sensitivity tests were performed to evaluate the model outputs and the results indicated that (a) the importance of collecting high-quality data for stormwater inputs into wetlands and (b) the importance of accurate estimation of the die-off rate in wetland microbial removal models. Our research showed that this model can be used to help design and rectify stormwater constructed wetlands for better faecal microbial removal, vegetation maintenance and support future real-time decision-making.

Arbuscular mycorrhizal symbiosis alleviates arsenic phytotoxicity in flooded Iris tectorum Maxim. dependent on arsenic exposure levels

Arsenic (As) pollution in wetlands has emerged as a serious global concern, posing potential threat to the growth of wetland plants. Arbuscular mycorrhizal fungi (AMF) can alleviate As phytotoxicity to host plants, but their ecological functions in wetland plants under flooding conditions remain largely unknown. Thus, a pot experiment was conducted using Rhizophagus irregularis and Iris tectorum Maxim. exposed to light (15 and 30 mg/kg As) and high (75 and 100 mg/kg As) levels of As, to investigate the intrinsic mechanisms underlying the effects of mycorrhizal inoculation on plant As tolerance under flooding conditions. The mycorrhizal colonization rates ranged from 31.47 ± 3.92 % to 60.69 ± 5.58 %, which were higher than the colonization rate (29.55 ± 13.60%) before flooding. AMF significantly increased biomass of I. tectorum under light As levels, together with increased phosphorus (P) and As uptake. Moreover, expression of arsenate reductase gene RiarsC and a trace of dimethylarsenic (1.87 mg/kg in shoots) were detected in mycorrhizal plants, suggesting As transformation and detoxification by AMF exposed to light levels of As. However, under high As levels, AMF inhibited As translocation from roots to shoots, and facilitated the formation of iron plaque. The immobilized As concentrations in iron plaque of mycorrhizal plants were respectively 1133.68 ± 179.17 mg/kg and 869.11 ± 248.90 mg/kg at 75 and 100 mg/kg As addition level, both significantly higher than that in non-inoculated plants. Irrespective of As exposure levels, mycorrhizal symbiosis decreased soil As bioavailability. Overall, the study provides insights into the alleviation of As phytotoxicity in natural wetland plants through mycorrhizal symbiosis, and potentially indicates function diversity of AMF under flooding conditions and As stress, supporting the subsequent phytoremediation and restoration of As-contaminated wetlands.

Distribution and sources of surface soil pollen in different coastal wetlands and their relationship with land cover: A case study of northwest Bohai Bay, north China

Understanding the relationship between modern pollen and vegetation in coastal wetlands is essential for reconstructing long-term land cover changes, and for determining the response of coastal wetland ecosystems to global changes. We selected 68 sampling sites in different types of coastal wetland in northwest Bohai Bay, North China, for palynological analysis, and hence to determine the relationships between pollen and environmental factors, such as soil grain size, salinity, and pH. A back-trajectory model and remote sensing LUCC data were used to reveal the pollen source area and the pollen representation for different land cover types. The results show that the pollen assemblages of these coastal wetlands are dominated by Chenopodiaceae and Poaceae. The pollen assemblages are significantly different between silty and sandy coastal wetlands, and they also reflect different vegetation landscapes. Chenopodiaceae pollen is a potential indicator of saline-alkali soil environments in coastal areas. In addition to the vegetation coverage and sedimentary environment, pollen concentrations are negatively correlated with the grain size of the surface soil. The pollen diversity is higher in areas with strong human influences (e.g., cultivated land, villages, roads), but lower in natural wetlands with a high vegetation coverage. The arboreal pollen is generally sourced from the northern and northwestern mountains, while the major dispersal area of halophyte and hygrophyte pollen is on a local scale, constrained by the local vegetation canopy and its settlement characteristics. Fern spores are mainly waterborne, carried by rivers and surface runoff from mountain areas. The arboreal and upland herbaceous pollen is over-represented for forest and grassland landscapes. Halophyte and hygrophyte pollen show a good correlation with the area of coastal wetland, and they can be used as an indicator of the extent of coastal wetland influenced by climate change and human activities.

Response of the Biological Components to Climate Change in the Wetland Ecosystem of the Qinghai-Tibet Plateau

Alpine wetlands play a role in water conservation, climate regulation, carbon sequestration, and biodiversity protection. However, due to the unique geological structure and climate characteristics of alpine areas, climate change is highly likely to have an impact on alpine wetlands and their ecosystems, including the abundance and distribution of local species. This paper focuses on analyzing the composition, quantity, and distribution changes of wetland organisms, including producers, consumers, and decomposers. The research findings indicate that, with the intensification of human activities and climate change such as global warming, despite the emergence of some new wetlands, many natural alpine wetlands on Qinghai-Tibet Plateau are facing shrinkage and are gradually retreating towards higher altitudes, latitudes, and wetter areas, which means the extinction of some plants and the shrinkage of wildlife habitats. Changes in wetland environment, such as drying, resulting from increased temperature and decreased precipitation, have led to a decline in biodiversity and degradation of alpine wetland ecosystems. Despite an overall increase in vegetation cover, wetland degradation has caused changes in plant species diversity and community composition. Climate warming have also affected wildlife migration and the activity of microorganisms. The changes in plateau wetlands are primarily shaped by climate conditions, while human activities act as accelerators, causing significant damage to wetland environments, leading to fragmentation and accelerated degradation. This paper proposes strengthening ecological monitoring and risk assessment in these regions, conducting further research, and promptly implementing necessary restoration measures to reduce the ecological risks caused by these changes.

Advantages of using a carbon-rich substrate in a constructed wetland for agricultural water treatment: Carbon availability and biota development

Proper bed substrate selection is essential for the growth of microorganisms and plants, which are key elements in constructed wetlands (CWs) performance. This is even more important in CWs that treat irrigated agricultural drainage water characterised by a high nitrogen (N), but low carbon (C) and phosphorus (P) concentration. This nutrient imbalance compromises biota activity and limits water treatment processes. Three substrates were tested in a CW field-scale pilot plant for 2 years: gravel (100%) and two mixed substrates, gravel + 30% natural wetland soil and gravel + 10% biochar. While gravel is one of the most commonly used substrates in subsurface flow CWs, soil has hardly been employed, and field-scale biochar application studies are scarce. We analysed the effect of adding a C-rich substrate to gravel on both nutrient imbalance correction and the biotic performance of CWs. Adding natural soil or biochar increased P availability in beds. However, the dissolved organic C concentration in interstitial water was only enhanced by soil addition. Unlike gravel, microbial density and activity, and Phragmites australis plant growth, were higher in beds with soil, followed by those with biochar. A similar pattern was observed for plant tissue quality. Although biochar proved positive for biota, it had a short-term effect as a source of C and P. Therefore, employing a suitable gravel-soil mixture provides notable advantages for the irrigated agricultural water treatment challenge. Even after considering some limitations, our results represent an important step to design CWs that treat this wastewater type and for eutrophication control in sustainable agroecosystems.

Examining the role of generativity on tourists’ environmentally responsible behavior: An inter-generational comparison

Sustainability means developing without compromising the benefit of future generations, which concurs with generative concern, a future value orientation characterized by concern for the future generation. Drawing on the value-attitude-behavior (VAB) hierarchy model, this study established a theoretical framework and empirically examined structural relationships among tourists' generativity, environmental concern, personal norm, and environmentally responsible behavior (ERB) via PLS-SEM. Potential generational differences were analyzed using an independent sample t-test and multigroup analysis. A total of 702 questionnaires from on-site tourists were collected in Xixi Wetland National Park, Hangzhou, China. Results showed that generative concern positively influences ERB, mediated by tourists’ environmental concern and personal norm. Additionally, inter-generational comparison indicated that Generation Z (Gen Z) has a lower level of generative concern but exhibited greater predictive power for ERB. The effect of environmental concern on personal norm is more robust among Gen Z. Further, academic implications and practical strategies were discussed.

Cechy charakterystyczne i parametryzacje dochodzącego promieniowania fotosyntetycznie czynnego w środkowym basenie Biebrzy = Characteristics and parametrisations of the photosynthetically active radiation incoming in the Middle Biebrza Basin

The availability of light is one of the most important factors that determine the photosynthesis process. Wave bands of solar radiation from 400 to 700 nm are called photosynthetically active radiation (PAR) because of their ability to stimulate the process of photosynthesis. The limited data availability and the regional and local PAR dependence cause the need for independent research, especially in areas of high natural value. The main goal of the work is to characterize the incoming photosynthetically active radiation in the Middle Biebrza Basin on the basis of a 9-year measurement series (2013-2021) from the Kopytkowo site (53°35'30.8”N, 22°53'32.4"E). The analysis was carried out for both instantaneous values and daily totals. In addition to the basic statistical characteristics, attention was paid to radiation on clear days and to the relationship between the PAR values on the Earth's surface and at the top of the atmosphere. Due to the limited availability of empirical data, simple parameterizations of PAR radiation were proposed for use in environmental studies. The research was carried out in the north-eastern part of Poland on the outskirts of Biebrza National Park in the Middle Biebrza Basin (Fig. 1). The area can be characterised as natural, almost unchanged, and uninhabited wetlands overgrown by swamp vegetation. The measurement site is located around 350 m north of the small village Kopytkowo with only a handful of permanent residents. The PQS1 PAR Quantum Sensor by Kipp &amp; Zonen mounted at height 2.7 m a.g.l. was used to collect data (Fig. 2). The sensor is part of the eddy-covariance system that measures the exchange of greenhouse gases between the ecosystem and the atmosphere. Data were sampled every 10 seconds and then stored in datalogger (CR500) as 5-minute averages. The results are shown as photosynthetic photon flux density (PPFD) with micromole per square metre per second (µmol∙m⁻²∙s⁻¹) as unit and were collected in Central European Time (CET).

Submerged macrophytes enhance carbon emission (CO2 and CH4) from the freshwater wetland in Keibul Lamjao National Park, Manipur, India

Worldwide, the exacerbation of global warming has accelerated the growth of submerged macrophytes in wetlands, thereby substantiating the supply of labile substrates for carbon (CH4 and CO2) emissions. Nevertheless, limited studies have been conducted on carbon emission from tropical wetlands with submerged macrophytes. In the current study an attempt has been made to reveal the role of submerged macrophytes in influencing carbon flux from a natural wetland in the Indo-Burma Biodiversity hotspots. The submerged macrophytes colonising the shallow freshwater wetland of Keibul Lamjao comprise of Hydrilla verticillata, Ceratophyllum demersum, and Potamogeton crispus, with primary productivity at community level ranging between 20.72 and 152.53 g m-2 d-1 (mean, 95.6 ± 54.66 g m-2 d-1). This study gives a comparative analysis of the carbon gases (CH4 and CO2) emission in two distinct zones of the wetland: areas with profuse submerged macrophytic growth and water free of macrophytes. The mean CO2 and CH4 emissions from the zone with submerged macrophytes were 8362.64 ± 2935.57 and 227.90 ± 73.50 mg m-2 d-1, respectively, compared to 5558.07 ± 1222.05 and 149.72 ± 20.44 mg m-2 d-1 from those without macrophytes. The CO2 and CH4 emissions peak during the summer and wane in the following seasons, with minimum emissions occurring during the winter. It is apparent from the results that the generation of the gases in the wetland was temperature dependent, plus the macrophytic detritus availability. The carbon emissions were significantly correlated with the physicochemical properties of the water and the lake bottom sediment. A significantly positive correlation between carbon emission and dissolved organic carbon (DOC) and organic matter (OM) was established in the zone with macrophytes, thereby revealing that the growth of submerged macrophytes in the wetland enhances atmospheric carbon emissions.

Plant traits associated with seed dispersal by ducks and geese in urban and natural habitats.

Ducks and geese are little studied dispersal vectors for plants lacking a fleshy fruit, and our understanding of the traits associated with these plants is limited. We analyzed 507 faecal samples of mallard (Anas platyrhynchos) and Canada goose (Branta canadensis) from 18 natural and urban wetlands in England, where they are the dominant resident waterfowl. We recovered 930 plant diaspores from 39 taxa representing 18 families, including 28 terrestrial and five aquatic species and four aliens. Mallards had more seeds and seed species per sample than geese, more seeds from barochory and hydrochory syndromes, and seeds that on average were larger and from plants with greater moisture requirements (i.e., more aquatic). Mallards dispersed more plant species than geese in natural habitats. Plant communities and traits dispersed were different between urban (e.g., more achenes) and natural (e.g., more capsules) habitats. Waterfowl can readily spread alien species from urban into natural environments but also allow native terrestrial and aquatic plants to disperse in response to climate heating or other global change. Throughout the temperate regions of the Northern Hemisphere, the mallard is accompanied by a goose (either the Canada goose or the greylag goose) as the most abundant waterfowl in urbanized areas. This combination provides a previously overlooked seed dispersal service for plants with diverse traits.

Impact of Climate Change on Water Sources and River‐Floodplain Mixing in the Natural Wetland Floodplain of Biebrza River

AbstractThe origins of river and floodplain waters (groundwater, rainfall, and snowmelt) and their extent during overbank flow events strongly impact ecological processes such as denitrification and vegetation development. However, the long‐term sensitivity of floodplain water signatures to climate change remains elusive. We examined how the integrated hydrological model HydroGeoSphere and the Hydraulic Mixing‐Cell method could help us understand the long‐term impact of climate change on water signatures and their spatial distribution in the protected Biebrza River Catchment in northeastern Poland. Our model relied on 20th century Reanalysis Data from 1881 to 2015 and an ensemble of EURO‐CORDEX simulations for representative concentration pathways (RCP) 2.6, 4.5, and 8.5 from 2006 to 2099. The historical component of the simulations was subjected to extensive multiple‐variable validation from 1881 to 2019. The results show that the extents of water sources were rather stable in the floodplain in the 1881–2015 period. The projected future impacts were variable with each analyzed RCP, but in all cases, different significant trends were present for the spatial distribution of water sources and for the river‐floodplain mixing. However, the total volume of water from different sources was less sensitive to climate change than the dominant sources and spatial distribution of water. The simulation results highlight the impact of climate change on the extent of water sources in temperate zone wetlands with significant implications for ecological processes and management. These results also underscore the urgent need to leverage such modeling studies to inform protective and preservation strategies of floodplain wetlands.

POLLUTION REMOVAL CAPACITIES OF AQUATIC PLANT SPECIES IN THE DATONG WETLAND PARK IN NORTH CHINA

The purification effect of a natural wetland landscape is often low when the focus is placed on the landscape effect. The effective combination of constructed wetland technology with landscape construction is challenging. Taking the Yuhe Wetland Park in Datong, Shanxi Province, China, as an example, the COD, phosphorus, and nitrogen removal capacities of aquatic plant species were determined, as well as the effects of the soil and the microbial communities. The highest COD and P removal capacity was observed for Typha orientalis Presl. which the purification rate reached 76.9% and 76.6%, and the highest N removal capacities were found for Scirpus validus Vahl., the rate of purification was 83.4%. Gram-negative bacteria were dominant.

Comparative Assessment of the Spatiotemporal Dynamics and Driving Forces of Natural and Constructed Wetlands in Arid and Semiarid Areas of Northern China

Arid and semiarid wetlands, the core geographical unit of desert oases, significantly benefit and improve the ecological environment. In this study, we systematically compared the spatiotemporal dynamics and driving forces of natural and constructed wetlands in arid and semiarid regions of northern China from 1995 to 2019. For these comparisons, we utilized a land-use transition matrix, partial least-squares–structural equation model (PLS-SEM), and geographically weighted regression (GWR) model. The results showed that (1) the area of wetlands as a whole showed an upward trend, with natural and constructed wetlands increasing by 4.16% and 11.86%, respectively. The increases mainly resulted from conversions of grassland and other lands (shrub, sparse vegetation, and bare land). (2) The direct dominant factors that drove natural wetland changes were soil and terrain, while those that drove constructed wetlands were human disturbances. Human disturbance, by affecting soil, had a higher significant indirect effect on natural wetlands. Heat, by affecting moisture, had the greatest indirect effect on constructed wetlands. (3) The sensitivity of natural and constructed wetlands to the responses of different drivers showed significant spatial heterogeneity. This study explores the interaction and driving mechanisms of human and natural attributes on natural and constructed wetlands and provides a scientific foundation for the restoration and sustainable development of wetlands in arid and semiarid areas.

Structural and functional perspectives of carbon filter media in constructed wetlands for pollutants abatement from wastewater

Constructed wetlands (CWs) represent the most viable artificial wastewater treatment system that works on the principles of natural wetlands. Filter media are integrally linked to CWs and have substantial impacts on their performance for pollutant removal. Carbon-derived substrates have been in the spotlight for decades due to their abundance, sustainability, reusability, and potential to treat complex contaminants. However, the efficiency and feasibility of carbon substrates have not been fully explored, and there are only a few studies that have rigorously analyzed their performance for wastewater treatment. This critical synthesis of the literature review offers comprehensive insights into the utilization of carbon-derived substrates in the context of pollutant removal, intending to enhance the efficiency and sustainability of CWs. It also compares several carbon-based substrates with non-carbon substrates with respect to physiochemical properties, pollutant removal efficiency, and cost-benefit analysis. Furthermore, it addresses the concerns and possible remedies about carbon filtration materials such as configuration, clogging minimization, modification, and reusability to improve the efficacy of substrates and CWs. Recommendations made to address these challenges include pretreatment of wastewater, use of a substrate with smaller pore size, incorporation of multiple filter media, the introduction of earthworms, and cultivation of plants. A current scientific scenario has been presented for identifying the research gaps to investigate the functional mechanisms of modified carbon substrates and their interaction with other CW components.

The Wetland Intrinsic Potential tool: mapping wetland intrinsic potential through machine learning of multi-scale remote sensing proxies of wetland indicators

Abstract. Accurate, unbiased wetland inventories are critical to monitor and protect wetlands from future harm or land conversion. However, most wetland inventories are constructed through manual image interpretation or automated classification of multi-band imagery and are biased towards wetlands that are easy to directly detect in aerial and satellite imagery. Wetlands that are obscured by forest canopy, that occur ephemerally, and that have no visible standing water are, therefore, often missing from wetland maps. To aid in the detection of these cryptic wetlands, we developed the Wetland Intrinsic Potential (WIP) tool, based on a wetland-indicator framework commonly used on the ground to detect wetlands through the presence of hydrophytic vegetation, hydrology, and hydric soils. Our tool uses a random forest model with spatially explicit input variables that represent all three wetland indicators, including novel multi-scale topographic indicators that represent the processes that drive wetland formation, to derive a map of wetland probability. With the ability to include multi-scale topographic indicators that help identify cryptic wetlands, the WIP tool can identify areas conducive to wetland formation while providing a flexible approach that can be adapted to diverse landscapes. For a study area in the Hoh River watershed in western Washington, USA, classification of the output probability with a threshold of 0.5 provided an overall accuracy of 91.97 %. Compared to the National Wetlands Inventory, the classified WIP tool output identified over 2 times the wetland area and reduced errors of omission from 47.5 % to 14.1 % but increased errors of commission from 1.9 % to 10.5 %. The WIP tool is implemented as an ArcGIS toolbox using a combination of R and Python scripts.

Mapping Coastal Wetlands and Their Dynamics in the Yellow River Delta over Last Three Decades: Based on a Spectral Endmember Space

The accurate mapping and analysis of coastal wetlands and their dynamics are crucial for local coastal wetland protection, sustainable social development, and biodiversity preservation. However, detailed mapping and comprehensive analysis of coastal wetlands remain scarce. In this study, we utilized Landsat-TM/OLI remote sensing data and employed the linear spectral mixture analysis (LSMA) method to map changes in coastal wetlands and analyze their dynamics in the Yellow River Delta (YRD) from 1991 to 2020. Our mapping results demonstrate high accuracy and are consistent with previous studies, boasting an overall accuracy exceeding 96%. During the period of 1991–2020, the YRD estuary expanded by approximately 8744.58 ha towards the east and north. The vegetation of P. australis and S. salsa underwent transformation due to agricultural practices or degradation to bare flats. Moreover, these areas saw extensive colonization by the invasive species S. alterniflora. Over the three decades, S. alterniflora expanded approximately 5 km along the coast, significantly impacting the local coastal wetland biodiversity. Furthermore, a considerable number of natural wetlands transitioned into human-made wetlands from 1991 to 2014. In particular, bare flats underwent substantial changes, transforming into aquaculture sites and salt exploitation areas. These dynamics in coastal wetlands had significant repercussions on local ecosystems, including wetland fragmentation, biodiversity depletion, and water pollution. However, post-2014, numerous wetland protection strategies were implemented, resulting in the restoration of natural wetlands. Detailed wetland mapping and dynamic analysis furnish valuable insights for the management, protection, and sustainable utilization of diverse coastal wetlands.