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Climate change and invasive species represent two intertwined global environmental challenges profoundly affecting freshwater ecosystems. This study uses Ecological Niche Modeling along with risk screening to delve into the preferences and potential distribution of Potamopyrgus antipodarum, an invasive species, in relation to climate zones and habitat types, shedding light on the critical importance of coastal wetlands and high soil organic carbon content in shaping habitat suitability. Our findings underscore that P. antipodarum exhibits a distinct affinity for cool temperate, moist climates, as well as temperate floodplain rivers, wetlands, and coastal areas. Notably, coastal wetlands, endowed with elevated soil organic carbon levels, emerged as pivotal habitats for this species. Projections indicated a significant expansion in North America, potentially extending into South America. Türkiye reveals an intriguing alignment between its habitat and the natural distribution areas of P. antipodarum, presenting potential for habitat contraction while still retaining a broader range compared to other regions. These potential expansions were predominantly driven by climate suitability, playing a pivotal role in the invasiveness of P. antipodarum, with anticipated future climate regimes exerting substantial influence on its dispersal capabilities. [ABSTRACT FROM AUTHOR]

Aim: Revealing the role of regional species pool size in community assembly rules is essential for extending the species‐pool framework to large‐scale community ecology, and thus for more comprehensive understanding of biodiversity formation. However, little has been done to couple the regional species‐pool effect into local ecological processes in soil fungal communities, which play essential roles in ecosystems worldwide. Here, we performed large‐scale soil surveys of fungal communities to examine the linkage between regional species pool size and Dispersal–Selection Relationships (DSRs), and their relations to community structure. Location: China. Time period: July–August 2019. Major taxa studied: Fungal communities. Methods: By conducting the nationwide soil survey of ~1200 samples from various ecosystems across China, including agricultural, forest, grassland, and wetland soils, we examined the linkage between regional species pool size and DSRs, and their relationship to fungal community structure. Results: We found that selection was negatively related to dispersal, which was consistent with the general view that the strength of selection is weakened by dispersal homogenization, and that this relationship was stronger in regions with larger species pools. Moreover, an increase in community dispersion was correlated with stronger effect size of DSRs, implying greater heterogeneity among fungal communities under larger species pools. Main conclusions: Our study clearly illustrates the association of regional species pool size with local assembly rules and community formation of soil fungi across terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Disparities in pH, conductivity, organic carbon (OC), nutrients, and moisture between the Asan Wetland and its periphery in the Western Himalaya, India, highlight the need to investigate influencing factors. This study thus addresses two gaps: (1) identifying key drivers for alkaline pH and elevated wetland concentrations and (2) understanding how different values outside the wetland relate to ecological processes. Asan Wetland soil samples, collected on April 15, 2023, underwent analysis for pH, electrical conductivity (EC), organic carbon (OC), organic matter (OM), available nitrogen (N), available phosphorus (P), potassium (K), sodium (Na), calcium (Ca), moisture content (M), total organic carbon (TOC), and total organic matter (TOM) using standard laboratory procedures, APHA, CPCB, and standard manual techniques. Within the wetland, results indicated that the soil is more alkaline (pH 8.50 ± 0.13) than the periphery in the concentrations of EC, N, K, and M were found to be higher compared to the corresponding concentrations outside the wetland, with mean values of 1.10 ± 0.15 ds/m, 364 ± 117.13 kg/ha, 86.42 ± 21.64 kg/ha, and 20.87 ± 1.50%, respectively. Conversely, outside the wetland, higher values of OC, OM, P, Na, Ca, TOC, and TOM were recorded (0.39 ± 0.23%, 0.66 ± 0.39%, 0.82 ± 0.35 ppm, 80.45 ± 8.46 ppm, 268.12 ± 61.12 ppm, 56.80 ± 0.33%, and 97.70 ± 0.57%, respectively). pH, EC, K, Ca, Na, and moisture content variations indicate location‐based differences. pH, TOM, TOC, and soil moisture were positively correlated within wetlands but negatively correlated with Na and N. In addition, moisture was positively correlated with pH and N but negatively correlated with Ca, K, Na, and P. The study concluded that the Asan Wetland exhibits distinct soil characteristics compared to its periphery, exhibiting location‐based differences while emphasizing these factors' interconnectedness. [ABSTRACT FROM AUTHOR]

Organohalides are widespread pollutants that pose significant environmental hazards due to their high degree of halogenation and elevated redox potentials, making them resistant to natural attenuation. Traditional bioremediation approaches, primarily relying on bioaugmentation and biostimulation, often fall short of achieving complete detoxification. Furthermore, the emergence of complex halogenated pollutants, such as per‐ and polyfluoroalkyl substances (PFASs), further complicates remediation efforts. Therefore, there is a pressing need to reconsider novel approaches for more efficient remediation of these recalcitrant pollutants. This review proposes novel redox‐potential‐mediated hybrid bioprocesses, tailored to the physicochemical properties of pollutants and their environmental contexts, to achieve complete detoxification of organohalides. The possible scenarios for the proposed bioremediation approaches are further discussed. In anaerobic environments, such as sediment and groundwater, microbial reductive dehalogenation coupled with fermentation and methanogenesis can convert organohalides into carbon dioxide and methane. In environments with anaerobic‐aerobic alternation, such as paddy soil and wetlands, a synergistic process involving reduction and oxidation can facilitate the complete mineralization of highly halogenated organic compounds. Future research should focus on in‐depth exploration of microbial consortia, the application of ecological principles‐guided strategies, and the development of bioinspired‐designed techniques. This paper contributes to the academic discourse by proposing innovative remediation strategies tailored to the complexities of organohalide pollution. [ABSTRACT FROM AUTHOR]

The article focuses on how meteorological factors, such as rainfall and temperature, influence changes in land use within the marshes of the Al-Majar Al-Kabir region in southern Iraq. Topics include the impact of temperature and rainfall on land cover types, the use of Landsat satellite data for monitoring these changes, and the implications for soil conservation and marshland management.

Wetland ecosystem service function provides and maintains the Earth's life system, which supports human and social development. However, in recent years, with the intensification of human social activities, the wetland area in northeast China has been reduced, and wetland ecosystem service function has been damaged. This paper evaluates the ecosystem service function of wetlands in northeast China based on the InVEST model, taking 40 prefecture-level cities as the evaluation unit, calculating the carbon stock, soil retention, and habitat quality of the wetlands in the study area and analyzing the drivers of changes in ecosystem service function using the PLUS model. The following results were obtained: temporally, the wetland carbon stock decreased from 754 Tg in 2000 to 688 Tg in 2020; the wetland soil retention increased from 24,424 Tg in 2000 to 33,160 Tg in 2010, and then decreased to 28,765 Tg in 2020; and the quality of wetland habitats was roughly unchanged. The wetland habitats in the study area were categorized into 5 types, classified as I, II, III, IV, or V, and the spatial changes in the 40 prefecture-level cities in northeast China were analyzed. The driving factors affecting the change in the wetland ecosystem service function were further analyzed, mainly focusing on changes in the wetland area itself. The influence of other land-use types and the influence of related policies were analyzed in three aspects, among which the GDP and spatial density of the population are social factors, and the elevation and slope are natural factors that provide larger contributions to the change in wetland area. The reduction in forest and grassland areas and the increase in cultivated land and construction land areas have a negative effect on the ecosystem service function of wetlands, and the implementation of relevant wetland protection policies promotes the ecosystem service function of wetlands. According to the problems faced by wetlands in different regions, the government formulates strategies that are in line with local development, with a view to implementing wetland ecological development in the northeast region in the new context, which will help to realize intensive land use and stimulate the vitality of the region. [ABSTRACT FROM AUTHOR]

The roles of Asgard archaea in eukaryogenesis and marine biogeochemical cycles are well studied, yet their contributions in soil ecosystems remain unknown. Of particular interest are Asgard archaeal contributions to methane cycling in wetland soils. To investigate this, we reconstructed two complete genomes for soil-associated Atabeyarchaeia, a new Asgard lineage, and a complete genome of Freyarchaeia, and predicted their metabolism in situ. Metatranscriptomics reveals expression of genes for [NiFe]-hydrogenases, pyruvate oxidation and carbon fixation via the Wood-Ljungdahl pathway. Also expressed are genes encoding enzymes for amino acid metabolism, anaerobic aldehyde oxidation, hydrogen peroxide detoxification and carbohydrate breakdown to acetate and formate. Overall, soil-associated Asgard archaea are predicted to include non-methanogenic acetogens, highlighting their potential role in carbon cycling in terrestrial environments. The roles of Asgard archaea in soil ecosystems are unclear. In this study, the authors report complete genomes and metatranscriptomic data of Asgard archaea that indicate a role in production and consumption of carbon compounds known to serve as substrates for methane production in wetland soils. [ABSTRACT FROM AUTHOR]

The intensification of the global hydrological cycle is anticipated to increase the variability of precipitation patterns. Brackish wetlands respond to changes in precipitation patterns by regulating the absorption and release of CO2 and H2O to maintain the stability of ecosystem functions. However, there is limited understanding of how the inter‐seasonal precipitation distribution (SPD) affects ecosystem CO2 and H2O exchange compared with annual precipitation totals. Here, we conducted four consecutive years of field experiments in a brackish wetland, manipulating the proportion of precipitation across different seasons while maintaining a constant annual precipitation total. We utilized five inter‐SPD proportions (+73%, +56%, control (CK), −56%, −73%) to examine the effects of SPD on ecosystem CO2 and H2O exchange. Our findings revealed that the annual ecosystem CO2 and H2O fluxes showed a trend of decreasing with the decrease in spring precipitation distribution. Among them, the annual net ecosystem CO2 exchange, evapotranspiration, carbon use efficiency and water use efficiency were shown to be more sensitive to decrease in spring precipitation distribution and increase in summer and autumn precipitation distribution. This negative asymmetric response pattern suggests that annual ecosystem CO2 and H2O exchange is primarily governed by seasonal precipitation variability, with spring soil water–salt dynamics identified as the key driver. Therefore, this association can be explained by the fact that drought of the early growth stage exacerbates soil salinization and inhibits vegetation colonization and growth, thereby greatly impairing the annual CO2–H2O exchange capacity of brackish wetlands. Our results emphasized that the spring extreme precipitation‐induced soil water–salt conditions will greatly influence CO2 and H2O exchange in brackish wetlands in the future. These findings are crucial for improving predictions of the carbon sequestration and water‐holding capacity of brackish wetlands. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Natural wetlands are mostly nitrogen-limited ecosystems, while reclamation stimulates the loss of nitrogen (N) in soils by shifting the N regime. To investigate the microbial mechanisms of the N regime shift, we first conducted a global meta-analysis to quantify the wetland reclamation impacts on soil mineral N pools and then a field campaign to sample 24 soil cores up to 100 cm depth in a natural wetland and a 23-year cultivated soybean field from the Sanjiang Plain in northeastern China. After wetland reclamation, the N regime was shifted to cause a potential risk of massive N loss in soils; their microbial mechanisms were revealed through metagenomic data. In cropland, the relative abundance of genes involved in nitrification and assimilatory nitrate reduction to ammonia (ANRA) were enriched while those in N fixation, mineralization, denitrification, and dissimilatory nitrate reduction to ammonia (DNRA) were diminished. Wetland reclamation substantially enhanced the relative abundance of genes involved in nitrification (except for genes for ammonia oxidation to NH2OH) and denitrification in surface (0–30 cm) soils but decreased them in subsurface (30–100 cm) soils. After wetland reclamation, the relative abundance of genes involved in denitrification and DNRA significantly reduced in spring and summer, but such patterns were not found in autumn and winter. This change enhanced potential microbial-driven N loss in spring and summer. The metagenomic data serve as surrogate data sources for quantifying soil roles on soil N cycles under land use change. [ABSTRACT FROM AUTHOR]

Microbial necromass carbon (MNC) has been identified as an essential component of a persistent soil carbon pool. However, the contribution of MNC to soil organic carbon (SOC) in wetlands remains unclear. This study aims to explore the contribution of MNC to SOC and the factors controlling its distribution in wetlands. The distribution pattern of MNC in drawdown areas was investigated in the inlet and center of the Dongting Wetland, China. Random forest modeling was performed to determine the relative importance of environmental variables to MNC. A partial least squares path model was performed to further explore the direct and indirect effects of environmental variables on MNC. The analyses showed that the MNC content was 2652.70–3314.64 mg kg−1, accounting for 23.16–31.65% of SOC in wetland soils. Compared to bacterial necromass carbon (BNC), fungal necromass carbon (FNC) contributed more to SOC accumulation (over 70% of total MNC) in wetland soils. MNC content and the contribution of BNC to MNC increased with soil depth. In addition, MNC in wetland soils was directly affected by dissolved total nitrogen (DTN) and dissolved organic carbon (DOC)/SOC (p < 0.001; standardized total effect = 0.81). The pH indirectly affected MNC by regulating carbon and nitrogen content, with a standardized total effect of 0.48. In wetland soils, the lower MNC content and lower contribution to SOC may be supported by the slow accumulation of necromass and potential necromass mining in nutrient-poor conditions. Carbon and nitrogen availability played a crucial role in controlling the MNC turnover process in wetland soils. [ABSTRACT FROM AUTHOR]

Fish production integrates changes in biomass from growth, reproduction, and mortality, and is a useful indicator for fisheries management. However, calculation of fish production has been limited by the intensive requirements for data on abundance, biomass, age structure, and vital rates, and so it is uncommon to find estimates of fish production for wetlands. We developed an approach to directly estimate production that is suitable for data-limited systems: a continuous time model of production describing individual growth over short time intervals with continuous time models of abundance and biomass over longer timescales. We applied this model for 18 Great Lakes coastal wetlands (GLCWs) on Lake Ontario, including Big Island Wetland (BIW). In BIW, most species were dominated in abundance and biomass by younger cohorts and, as a result, these young, fast-growing individuals contributed disproportionately to fish production. In total, BIW produced 336.1 kg·ha·year of fish and the other 17 neighbouring ranged between 447.7 and 1119.9 kg·ha·year. These are some of the first estimates of fish production for GLCWs, highlighting their value for managing Great Lakes fisheries. [ABSTRACT FROM AUTHOR]

The occurrence of vegetation degradation may greatly affect the soil organic carbon (SOC) composition and carbon pool of wetland meadows in the Qinghai-Tibet Plateau (QTP). However, it is currently unclear how SOC will change under different degrees of degradation. Therefore, we studied the wetland meadows of Maqu, China on the eastern edge of the QPT with different degrees of vegetation degradation (undegraded (UD), light degraded (LD), moderately degraded (MD) and severely degraded (HD)), analyzed the impact of vegetation degradation on SOC composition, and calculated the carbon storage management index (CPMI). The results showed that the degradation of vegetation significantly reduces the SOC content of the Maqu wetland. With the aggravation of vegetation degradation, the proportion of SOCs in different fractions showed significant differences, especially in the topsoil layer. The mean CPMI value from 0-40 cm of LD, MD and HD has decreased by 47.29%, 41.64%, and 51.73% respectively compared to UD. It can be seen that vegetation degradation significantly increasing the carbon pool activity index (CAI) of Maqu. Our study suggested that vegetation degradation could considerably reduce the carbon pool index, which decrease the storage of wetland carbon, gradually undermine or even depleting the carbon sink capacity of QTP wetland system. [ABSTRACT FROM AUTHOR]

The Tibetan Plateau is well‐known for its expansive wetland environments. Hydric soils, a fundamental component of these environments, exhibit diverse hydraulic characteristics attributable to their varied botanical and mineralogical composition and their inherent porous structures. Nonetheless, research on the hydraulic properties of such soils in Tibet remains notably underrepresented relative to European and Canadian regions. Consequently, in this study, we evaluate the effectiveness of different unsaturated hydraulic schemes in equilibrium and examine the parameter uncertainty of 14 undisturbed samples collected from four soligenous wetlands. The findings suggest that both the van Genuchten and Kosugi functions, when integrated with the Peters‐Iden‐Durner (PDI) model, yield a nearly consistent fit to experimental observations and demonstrate strong identifiability of parameters. This indicates that the PDI model can accurately characterize hydraulic properties across the complete moisture range of hydric soils. Analysis of samples with a low clay content and no sphagnum suggests that the intertwined, twisted, and hollow residues of herbaceous vascular tissues do not create a distinct, independent macro‐pore system. Therefore, the unimodal scheme integrating the PDI model is adequate. However, for samples that exhibit nonmonotonicity of the first‐order derivative of the retention curve, such as uncompacted samples containing sphagnum or samples rich in clay, the integration of the PDI model into the bimodal scheme boosts accuracy while having almost negligible impact on identifiability. The varied observed hydraulic properties of only 14 samples underscore the necessity for extensive hydric‐soil sampling and hydraulic analysis across the expansive and varied wetland landscapes on the Tibetan Plateau. Plain Language Summary: The alpine wetlands of the Tibetan Plateau have given rise to a diverse array of wetland soils. Considering the plateau monsoon climate characteristics, this study focuses on soil water retention and unsaturated hydraulic conductivity across the complete soil moisture range. The results indicate that, regardless of the non‐hydraulic physical properties of these wetland soils, employing a hydraulic model that integrates capillary flow models with a simplified film flow model can significantly enhance the accuracy of the inverse modeling method in determining hydraulic properties. Given the diverse wetland environments and the vast expanse of the Tibetan Plateau, it is essential to conduct extensive field soil sampling and laboratory analysis to gain a comprehensive understanding of the soil hydraulic properties. Currently, the hydraulic parameters provided by this study may be reasonable choices for simulating land surface and hydrological processes related to the plateau wetland soils. Key Points: A pioneering analysis determines the hydraulic properties of hydric soils on the Tibetan PlateauDiverse hydraulic properties and their association with varied vegetation remnants and mineral compositions are revealedA basis is provided for selecting soil unsaturated hydraulic schemes for Tibetan wetlands and peatlands [ABSTRACT FROM AUTHOR]

The Intermediate Disturbance Hypothesis (IDH) posits that maximal plant biodiversity is attained in environments characterized by moderate ecological disturbances. Although the applicability of the IDH to microbial diversity has been explored in a limited number of studies, there is a notable absence of experimental reports on whether soil microbial 'activity' demonstrates a similar response to the frequency or intensity of environmental disturbances. In this investigation, we conducted five distinct experiments employing soils or wetland sediments exposed to varying intensities or frequencies of disturbances, with a specific emphasis on disturbances associated with human activity, such as chemical contamination, hydrologic changes, and forest thinning. Specifically, we examined the effects of bactericide and heavy metal contamination, long-term drainage, tidal flow, and thinning management on microbial enzyme activities in soils. Our findings revealed that microbial enzyme activities were highest at intermediate disturbance levels. Despite the diversity in experiment conditions, each trial consistently demonstrated analogous patterns, suggesting the robustness of the IDH in elucidating microbial activities alongside diversity in soils. These outcomes bear significant implications for ecological restoration and management, as intermediate disturbance may expedite organic matter decomposition and nutrient cycles, crucial for sustaining ecosystem services in soils. [ABSTRACT FROM AUTHOR]

Coastal wetlands adapt to rising seas via feedbacks that build soil elevation, which lead to wetland stability. However, accelerated rates of sea-level rise can exceed soil elevation gain, leading to wetland instability and loss. Thus, there is a pressing need to better understand regional and landscape variability in rates of wetland soil elevation change. Here, we conducted a regional synthesis of surface elevation change data from mangrove forests and coastal marshes in the iconic Greater Everglades region of south Florida (USA). We integrated data from 51 sites in which a total of 122 surface elevation table-marker horizon (SET-MH) stations were installed. Several of these sites have been periodically monitored since the 1990s and are among the oldest SET-MH datasets in the world. Rates of surface elevation change ranged from −9.8 to 15.2 mm year−1, indicating some wetlands are keeping pace with sea-level rise while others are at risk of submergence and conversion to open water. Vertical accretion rates ranged from 0.6 to 12.9 mm year−1, and subsurface change rates ranged from −13.5 to 8.6 mm year−1. Rates of surface elevation change were positively related to subsurface change but not vertical accretion. There were no significant relationships between rates of surface elevation change and elevation (NAVD 88) or rates of sea-level rise. Site-specific examples indicate that hurricanes, plant productivity, hydrologic exchange, and proximity to sediment and nutrient inputs are critical but confounding drivers of surface elevation change dynamics in the Greater Everglades region. Collectively, our results reinforce the value of long-term SET-MH data that incorporate spatial variability for advancing understanding of surface elevation change dynamics in coastal wetlands. [ABSTRACT FROM AUTHOR]

Coastal wetlands experience acute and chronic disturbances which can affect rates of surface elevation change and vertical accretion of surface sediments. Disturbance can either amplify or impair the ability of wetlands to maintain their position within the tidal frame, with implications for their long-term persistence. Using an 8-year dataset collected from coupled surface elevation table-marker horizon (SET-MH) stations spanning riverine, bayside, and barrier island settings in the Apalachicola Bay region of north Florida, USA, this study investigated decadal-scale surface elevation change and vertical accretion rates to assess wetland vulnerability to acute (Hurricane Michael) and chronic (relative sea-level rise; RSLR) disturbance in different geomorphic settings. All sites had long-term accretion rates that exceeded rates of surface elevation change (pre-Michael), indicating that surface accretion was not a good indicator of changes in surface elevation for any of these coastal geomorphic settings. Hurricane Michael increased surface elevation change rates at bayside and riverine sites; barrier island sites consistently displayed the lowest surface elevation change rates, which did not differ between pre- and post-Michael periods. Accretion rates were greatest in the riverine sites, which were characterized by highly organic soils. Barrier island and bayside sites demonstrated elevation and accretion deficits relative to the rate of RSLR for Apalachicola Bay between 2010 and 2022, indicating high vulnerability of these sites to chronic increases in sea level. These estimates of marsh resilience relied exclusively on rates of vertical change and neglecting to account for lateral erosion failed to predict that each of the three barrier island sites experienced rapid loss of the seaward SET-MH stations during the observation period. These results provide evidence of different vertical change responses among coastal wetlands of three geomorphic settings exposed to hurricanes and RSLR in the same region and suggest different timelines for long-term persistence of these sites. [ABSTRACT FROM AUTHOR]

The low rice production level in Africa is attributed to poor soil fertility despite the potential for rice cultivation in the inland valleys. This study was conducted to evaluate soil characteristics in some lowlands that have been continuously and intensively used for rice production for over two decades in southwestern Nigeria. Soil physical, chemical, and mineralogical properties, as well as phosphorus sorption characteristics, were assessed in soil samples collected from diagnostic horizons of profiles in six benchmark soils. The results show kaolinite, quartz, potassium(K)-feldspars, and mixed-layered smectite as the predominant minerals. The iron oxide fractions indicate that the soils are at varying degrees of development where the soils at the advanced stage of development are predominantly rich in kaolinite and quartz with a high concentration of total pedogenic iron oxide and generally low in soil fertility. Soil phosphorus buffering capacity is low and varies inversely with pH, confirming the deficiency of phosphorus at low pH. Short-range-order (SRO) iron (Fe) oxides show a strong affinity for phosphorus and this is stronger at lower soil horizons and mediated by some redoxomorphic reactions. The SRO iron oxide concentration has more influence on phosphorus retention in soils rather than the absolute concentration of iron oxides. The study concludes that SRO Fe oxides and soil pH are the major edaphic factors playing a prominent role in phosphorus retention and availability in the wetland soils rather than the clay minerals. [ABSTRACT FROM AUTHOR]

Invasive Spartina alterniflora has significant impacts on sediment carbon pool and turnover in the tidal wetlands of estuaries and coasts. Yet, how this exotic S. alterniflora affects sediment organic carbon mineralization dynamics remains poorly understood. In this study, sediment geochemical properties, organic carbon fractions, and mineralization dynamics were examined in a native Cyperus malaccensis habitat and three invasive S. alterniflora habitats (6-, 10-, and 14-year-old) in summer and winter. We found that invasive S. alterniflora generally increased sediment total organic carbon and their labile fraction contents. The organic carbon mineralization rates and cumulative carbon mineralization amounts were significantly influenced by invasive S. alterniflora, and their values increased with this exotic plant invasion chronosequences. The mineralization rates and cumulative mineralization amounts were also characterized by higher values in surface sediment (0 - 10 cm depth) compared to subsurface sediment (10 - 20 cm depth) and by seasonal variations with higher values in summer than in winter. The sediment organic carbon labile fractions, rather than total organic carbon, were the most important factor affecting carbon mineralization dynamics. The cumulative carbon mineralization amounts exhibited an excellent fit to the first-order kinetic equation (R2 = 0.93). The changes in modeled kinetic parameters (potential carbon mineralization amounts (C0) and carbon mineralization rate constant (k)) among these four habitats were similar to carbon mineralization rates, implying invasive S. alterniflora promoted the availabilities of organic compounds for microbial respiration metabolism. Overall, our findings highlighted the importance of S. alterniflora invasion in accelerating organic carbon decomposition and carbon dioxide release potential, although it also increases carbon accumulation. [ABSTRACT FROM AUTHOR]

Wetlands comprise unique water storage and conveyance mechanisms that maintain landscape integrity under the sub-humid climate in the Athabasca Oil Sands Area. In addition to their internal function, wetlands support a two-way hydrological connection to adjacent uplands and provide water for downstream water courses. Understanding the role of wetlands as integral parts of surface water (SW)–groundwater (GW) exchange can provide insights into the functioning of the hydrological system as a whole and contribute to thoughtful water management strategies and better coordination of monitoring efforts in the areas affected by oil sands (OS) activities. As such, this study summarizes the current state of hydrological knowledge on the role of wetlands in SW–GW interactions based on studies conducted within the Western Boreal Plains. In particular, the role of wetland soils and their properties in SW–GW interactions, the effects of wetlands on landscape hydrological connectivity and watershed runoff, and features of "wetland–aquifer" and "wetland–open waterbody" interactions were reviewed. Given that alterations of SW–GW interactions in wetlands can occur as a result of anthropogenic disturbances, the coordination of GW, SW, and wetland monitoring efforts and targeting areas where increased SW–GW exchange occurs would be beneficial for the economic and logistical efficiency of the OS monitoring network. [ABSTRACT FROM AUTHOR]

Interstitial water or pore water occupies the space between soil particles and provides "hotspots" and "fluvial networks" for microbial activities in floodplain soil. However, to date, we know very little about the microorganisms living in pore water and how they respond to environmental changes. This study aimed to understand microbial distribution and assemblage in riparian pore waters, and how they respond to water chemistry and redox gradients associated with hydrological processes.We analysed the annual changes of porewater microbial communities from the east and west banks of the White Clay Creek, a site at the Christina River Basin – Critical Zone Observatory, Pennsylvania, USA. Microbial abundances were quantified by epifluorescence microscopy and detailed community structures were characterised by high‐throughput sequencing. Water chemistry and redox gradients were also monitored and recorded, and their interactions with porewater microbiomes were analysed using correlations and multivariate analyses.Abundance of microbial cells increased during summer and late autumn. Wetland porewater microbiomes mainly contained Acidobacteria, Bacteroidetes, Nitrospirae and Proteobacteria, and microbiome structures were easily distinguishable from those in the underlying hyporheic gravel layer. Seasonal dynamics of bacterial community structure in the east and west wetlands were distinct, responding to floodplain topography and associated hydrological/geochemical processes. Iron (Fe)‐cycling bacteria (mainly Gallionellaceae and Rhodoferax spp.) dominated the porewater microbiome, and their relative abundance was significantly higher in the east than the west wetland. Furthermore, Fe‐oxidising bacteria (Gallionellaceae) were negatively correlated with Fe‐reducing bacteria (Rhodoferax spp.) at the east wetland.Microbial abundances (cell density) in pore waters showed similar seasonal patterns across stream banks, but microbial community structure did not. Microbiome assembly in pore water is correlated with water chemistry and redox gradients primarily associated with local hydrological processes.As a consequence of their significance for carbon (C) mineralisation and Fe reduction at terrestrial–aquatic interfaces, microbiomes in riparian pore waters and associated microbial activity play an essential role in C and mineral dynamics. These findings will inform future studies of the response of freshwater ecosystems to hydrological dynamics influenced by global climate change. [ABSTRACT FROM AUTHOR]

The Glenorchy area of northwest Otago consists of a low-relief Holocene fluvial delta complex below glaciated mountains of Otago Schist basement, and has locally elevated arsenic (As) from two geogenic pathways: Mesozoic hydrothermal processes and Holocene shallow groundwater transport. Soils on the delta complex are primitive and contain abundant sand and silt derived from unoxidised schist basement, with background As contents generally <30 mg/kg. Some soils in wetland areas on the delta have naturally elevated (geogenic) arsenic contents that are locally >300 mg/kg on the cm2 scale. Arsenic enrichment has occurred in the upper 30 cm where dissolved As and Fe from low-redox chemical conditions in shallow groundwater has become oxidised, thereby lowering their solubility. Both As and Fe are being mobilised from background sulfide minerals in schist-derived debris, and groundwater As concentrations up to 0.8 mg/L have been recorded. Historic mining of scheelite for tungsten on the surrounding mountains has exposed small volumes (typically tens to hundreds of m3) of arsenopyrite-bearing mine wastes with spot As contents from <500 to >10 000 mg/kg. Water discharging from mine adits have pH∼8 and dissolved As up to 0.3 mg/L, but these waters are rapidly diluted downstream to <0.02 mg/L. [ABSTRACT FROM AUTHOR]

Purpose: Machine learning models can improve the prediction of spatial variation of wetland soil properties, such as soil moisture content (SMC) and soil organic matter (SOM). Their performance, however, relies on the quantity of data used to train the model, limiting their use with insufficient data. In this study, we assessed the use of synthetic data constrained by limited field data for training an eXtreme Gradient Boosting (XGBoost) algorithm used to predict the distribution of soil properties based on geophysical measurements constrained by soil samples. Materials and methods: A spatial distribution of soil apparent electrical conductivity (ECa) and laboratory measurements of SOM and SMC from twenty-two core samples were acquired at the St. Michael restored wetland near Defiance, Ohio. The correlations between ECa, SOM, and SMC were explored for predicting the spatial distribution of SOM and SMC. We used a Beta Variational AutoEncoder (β-VAE) approach to synthetically generate over 70,000 training data from the original twenty-two data from soil cores. The training data samples were taken from the latent space. The XGBoost algorithm was then trained on the β-VAE generated data and used to predict the spatial distribution of SOM and SMC at the site. We also validated the accuracy of the XGBoost predictions using an original holdout model validation technique. Results and discussions: The generated synthetic data using the β-VAE include both soil attributes and ECa, which are larger and more diverse than the original training set with an absolute mean reconstructed error for SMC and SOM ranging from 0.018 to 0.022 and 0.026 to 0.041, respectively. This indicates that the β-VAE successfully generated a realistic synthetic dataset and overcame the technical barrier of using limited datasets. In addition, using generated data to expand the original training data helps the XGBoost model make more accurate predictions compared to training on the original data. The XGBoost prediction performance yielded average Lin's concordance correlation coefficient (LCCC) values of 0.82 and 0.85 for SOM and SMC and a ratio of performance to deviation (RPD) values of 1.92 and 2.22 respectively, indicating a good performance. Conclusions: This study validated the use of β-VAE to successfully generate synthetic wetland soil datasets with attributes of the original field data that can be effectively used to train the machine learning XGBoost model. The proposed framework offers an efficient solution for mapping the spatial variability of soil property in data-scarce wetland soil environments. [ABSTRACT FROM AUTHOR]

Methane (CH4) is a potent greenhouse gas emitted by archaea in anaerobic environments such as wetland soils. Tidal freshwater wetlands are predicted to become increasingly saline as sea levels rise due to climate change. Previous work has shown that increases in salinity generally decrease CH4 emissions, but with considerable variation, including instances where salinization increased CH4 flux. We measured microbial community composition, biogeochemistry, and CH4 flux from field samples and lab experiments from four different sites across a wide geographic range. We sought to assess how site differences and microbial ecology affect how CH4 emissions are influenced by salinization. CH4 flux was generally, but not always, positively correlated with CO2 flux, soil carbon, ammonium, phosphate, and pH. Methanogen guilds were positively correlated with CH4 flux across all sites, while methanotroph guilds were both positively and negatively correlated with CH4 depending on site. There was mixed support for negative relationships between CH4 fluxes and concentrations of alternative electron acceptors and abundances of taxa that reduce them. CH4/salinity relationships ranged from negative, to neutral, to positive and appeared to be influenced by site characteristics such as pH and plant composition, which also likely contributed to site differences in microbial communities. The activity of site‐specific microbes that may respond differently to low‐level salinity increases is likely an important driver of CH4/salinity relationships. Our results suggest several factors that make it difficult to generalize CH4/salinity relationships and highlight the need for paired microbial and flux measurements across a broader range of sites. Plain Language Summary: Sea level rise will lead to increases in salinity in coastal wetlands and estuaries. Salinity is a key variable that controls the amount of greenhouse gases emitted from coastal wetlands, but we do not know if increases in salinity will increase or decrease emissions of the potent greenhouse gas methane, which is produced by microorganisms in wetlands. We examined salinity‐methane relationships at four different sites in the United States, and assessed how environmental factors and microorganism communities affected those relationships. We found discrepancies in salinity‐methane relationships that are likely driven by site‐specific communities of microorganisms that may respond differently to increasing salinity. Relationships between methane emissions and environmental variables were not consistent across sites, highlighting the difficulty of making generalizations about methane emissions from coastal wetlands and how they will respond to seawater intrusion. Key Points: Salinity‐methane relationships are variable across sitesRelationships between nutrients, alternative electron acceptors, and methane flux were not consistent across sitesCoastal wetland microbial consortia are site‐specific and may respond differently to seawater intrusion, with implications for methane flux [ABSTRACT FROM AUTHOR]

Morphogenetic properties and geochemical compositions were analyzed and assessed to improve our understanding of pedogenesis and geochemistry of wetland soils on the Abeokuta formation of Ogun State, Nigeria. Three profiles were dug to a depth of 1.2 m except where the water table is high, and examined for their morphological, physical, chemical, and geochemical compositions using standard laboratory techniques. Gleying (mottles) were present in some of the subsurface horizons, and dark greyish colour dominates the soil matrix. The particle size is dominated by sand fractions and the clay fraction increases with depth. The soil pH was moderately acid to neutral (4.6–6.8) and the organic carbon contents were low to high (4.9–43.1 g/kg). The exchange site was dominated by Ca and Mg, while Fe and Mn contents were higher among the micronutrients. Kaolinite, quartz, and degraded mica were the dominant minerals in the clay fractions. The geochemical results reveal that the order of abundance of major oxides is SiO2 > Al2O3 > Fe2O3 > CaO > MgO > Na2O > TiO2 ≥ K2O. Geochemical indices point to a moderate degree of weathering and pedogenesis. Higher contents of SiO2 and Al2O3 and calcium in the surface layers indicate relative enrichment of minerals during weathering and nutrient cycling by vegetation. [ABSTRACT FROM AUTHOR]

This study investigates the status of heavy metal pollution in the soils of Yuncheng Salt Lake Wetland. In April 2023, surface soil samples from the area were collected and analyzed for eight heavy metals, namely arsenic (As), cadmium (Cd), zinc (Zn), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni), and mercury (Hg). Utilizing the potential ecological risk index method and a health risk model, we evaluated both the ecological and health risks posed by soil heavy metals, providing valuable insights for local environmental management, ecological restoration, and human health risk mitigation. The findings indicate that the wetland's surface soil is strongly alkaline, with the average concentrations of the eight studied heavy metals ranking as follows: Zn>Cr >Pb >Cu>Ni > As >Hg >Cd, where Zn and Cr together constitute over 53.21% of the total. The spatial distribution of these metals in the soil shows minimal variation, with the highest concentrations found in the southern part of the study area. According to national soil quality benchmarks, both the individual and combined potential ecological risks in the area are deemed minor. Moreover, the analysis suggests no carcinogenic risk to either adults or children from exposure to these heavy metals. However, while the non-carcinogenic risk from individual metals is considered acceptable, exposure to combined metals could present a non-carcinogenic risk to children. [ABSTRACT FROM AUTHOR]

Tidal marshes are significant sources of colored (or chromophoric) dissolved organic carbon (CDOC) to adjacent waters and, as a result, contribute substantially to their optical complexity and ultimately affect their water quality. Despite this, our mechanistic understanding of the processes that regulate the exchange and transformation of CDOC at the tidal marsh–estuarine interface remains limited. We hypothesized that tidal marsh soils regulate this exchange and transformation subject to soil mineralogy and salinity environment. To test this hypothesis, we generated initial mass sorption isotherms of CDOC and noncolored dissolved organic carbon (NCDOC) using anaerobic batch incubations of Great Dismal Swamp DOC with four tidal wetland soils, representing a range of organic carbon content (1.77 ± 0.12 % to 36.2 ± 2.2 %) and across four salinity treatments (0, 10, 20, and 35). CDOC sorption followed Langmuir isotherms that were similar in shape to those of total DOC, but with greater maximum sorption capacity and lower binding affinity. Like isotherms of total DOC, CDOC maximum sorption capacity increased and binding affinity decreased with greater salinity. Initial natively adsorbed colored organic carbon was low and increased with soil organic content. In contrast, NCDOC desorbed under all conditions with desorption increasing linearly with initial CDOC concentration. This suggests that for our test solutions CDOC displaced NCDOC on tidal marsh soils. Parallel factor analysis of 3-D excitation emission matrices and specific ultraviolet absorbance measurements suggested that CDOC sorption was driven primarily by the exchange of highly aromatic humic-like CDOC. Taken together, these results suggest that tidal marsh soils regulate export and composition of CDOC depending on the complex interplay between soil mineralogy, water salinity, and CDOC vs. NCDOC composition. [ABSTRACT FROM AUTHOR]

In semi‐arid Mediterranean regions, particularly in some wetland soils, salinity is thought to be an indicator of low‐quality soils. In this study, a characterization is presented of the soils surrounding El Hito saline pond (Castilla La Mancha, Central Spain), an ecological halophyte niche within a natural semi‐arid steppe land. The main aim is to classify the salt‐affected soils and their morphology, genesis, and physico‐chemical properties. Four soil profiles were opened with a backhoe machine for sampling and subsequent description on the basis of their pedogenetic morphology. Systematic surface sampling was also performed. Standard methods were followed to measure the soil properties of 27 samples. Overall electrical conductivity (EC) and pH levels of the wetland were mapped (using ArcGIS 3.1.3). Soil salinity at elevated levels was detected, inhibiting plant uptake of water and nutrients. Distinct sub‐areas of extreme elevated surface salinity providing specialized plant habitats and poor soil structure were observed, as well as a mainly whitened‐yellowish‐greenish soil colour due to salt accumulation and poor drainage. The soils also showed alkaline pH values. In most samples, the pH was over 8.5, and EC was higher than 4 (dS m−1), and in several samples higher than 20 (dS m−1). A low sodium (Na) content was detected in the saturation extract where magnesium (Mg+) was the dominant soluble cation, followed by both calcium (Ca+) and sodium (Na+), and then potassium (K+), present in lower proportions. Sulphate (SO42−) and then chloride (Cl−) anions were dominant, although carbon trioxide, (CO3−) and carbonate (CO32−) anions were also present. The percentages of organic carbon (C) were very low, while total nitrogen (TN) and available phosphorus (P) were higher in the upper horizons, suggesting a degree of eutrophication. The present work will increase the existing knowledge about the role of El Hito saline pond, that play a vital ecological role in the broader biosphere, providing new suggestions to readers on how this knowledge can be used to improve these types of ecosystems. In particular, the agricultural pesticides and fertilizers continuously damage the soil fertility as evidenced by the high content of soluble phosphorus found in some points of the Hito saline pond. [ABSTRACT FROM AUTHOR]

Premise of research. Chamaecrista fasciculata is a widespread species harboring intraspecific morphological and ecological variability. Taxonomists have previously recognized intraspecific variants of C. fasciculata at specific, varietal, and ecotypic levels, but studies have not tested the hypothesis that these variants are genetically differentiated. In this study, we quantified genetic variation in populations of C. fasciculata to assess genetic differentiation and structure of the tidal freshwater endemic form, var. macrosperma , from the more common upland form, var. fasciculata. Methodology. Population genetic variation was quantified by genotyping 240 plants across 11 populations (8 var. fasciculata and 3 var. macrosperma) with 15 microsatellite loci. We compared genetic variation between the varieties, tested for geographic structure and historical bottlenecks in each population, and identified potential intervarietal hybrids. Pivotal results. Lower allelic diversity and heterozygosity were found in var. macrosperma , but these populations harbored more private alleles than var. fasciculata. Analysis of molecular variance indicated that 6% of the variation resides between the varieties, and Bayesian assignment analysis supported two genetic clusters, which align with morphological distinction of the varieties. Despite occurring in distinct habitats, admixture was found in all populations. Genetic bottlenecks were detected in some populations, which may reflect founder events from small numbers of seeds and the ephemeral nature of populations of this annual species. Conclusions. Given the significant genetic differentiation observed between the varieties, we recommend the continued taxonomic distinction of these varieties. The infrequent occurrence of var. macrosperma in tidal freshwater wetlands in combination with the strong genetic differentiation among populations we identified here is a conservation concern for this taxon. To preserve genetic diversity of var. macrosperma , efforts should focus on maintaining all extant populations and preserving suitable habitat to allow for colonization of new populations. [ABSTRACT FROM AUTHOR]

Alpine wetlands are critical ecosystems for global carbon (C) cycling and climate change mitigation. Ecological restoration projects for alpine grazing wetlands are urgently needed, especially due to their critical role as carbon (C) sinks. However, the fate of the C pool in alpine wetlands after restoration from grazing remains unclear. In this study, soil samples from both grazed and restored wetlands in Zoige (near Hongyuan County, Sichuan Province, China) were collected to analyze soil organic carbon (SOC) fractions, arbuscular mycorrhizal fungi (AMF), soil properties, and plant biomass. Moreover, the Tea Bag Index (TBI) was applied to assess the initial decomposition rate (k) and stabilization factor (S), providing a novel perspective on SOC dynamics. The results of this research revealed that the mineral-associated organic carbon (MAOC) was 1.40 times higher in restored sites compared to grazed sites, although no significant difference in particulate organic carbon (POC) was detected between the two site types. Furthermore, the increased MAOC after restoration exhibited a significant positive correlation with various parameters including S, C and N content, aboveground biomass, WSOC, AMF diversity, and NH4+. This indicates that restoration significantly increases plant primary production, litter turnover, soil characteristics, and AMF diversity, thereby enhancing the C stabilization capacity of alpine wetland soils. [ABSTRACT FROM AUTHOR]

Soil nitrogen and phosphorus are directly related to soil quality and vegetation growth and are, therefore, a common research topic in studies on global climate change, material cycling, and information exchange in terrestrial ecosystems. However, collecting soil hyperspectral data under in situ conditions and predicting soil properties, which can effectively save time, manpower, material resources, and financial costs, have been generally undervalued. Recent optimization techniques have, however, addressed several of the limitations previously restricting this technique. In this study, hyperspectral data were taken from surface soils under different vegetation types in the wetlands of the Shaanxi Yellow River Wetland Provincial Nature Reserve. Through in situ original and first-order differential transformation spectral data, three prediction models for soil carbon, nitrogen, and phosphorus contents were established: partial least squares (PLSR), random forest (RF), and Gaussian process regression (GPR). The R² and RMSR of the constructed models were then compared to select the optimal model for evaluating soil content. The soil organic carbon, total nitrogen, and total phosphorus content models established based on the first-order differential had a higher accuracy when modeling and during model validation than those of other models. Moreover, the PLSR model based on the original spectrum and the Gaussian process regression model had a superior inversion performance. These results provide solid theoretical and technical support for developing the optimal model for the quantitative inversion of wetland surface soil carbon, nitrogen, and phosphorus based on in situ hyperspectral technology. [ABSTRACT FROM AUTHOR]

Hydropedology is an interdisciplinary field that studies the interactions between soil and water, recognizing that soils influence hydrological processes through their hydraulic properties, and serve as indicators of hydrological behaviour through their morphological properties that are shaped by water regimes. Given the practical implications of hydropedology and its integration into South Africa's latest soil classification system, an updated categorization of soil forms and 1 657 (1 629 + 28) families was necessary, organizing them into three overarching response groups based on their predominant hydrological responses: recharge, interflow, and responsive. Within these groups, recharge soils are further classified into deep, shallow, and slow subgroups, interflow soils encompass soil/bedrock, shallow, and slow categories, while responsive soils are subdivided into responsive shallow and responsive wet. This paper aims to enhance the reader's comprehension of hydrological responses and simplify the intricacies integrated into South Africa's official soil classification system. [ABSTRACT FROM AUTHOR]

Redox processes, aqueous and solid‐phase chemistry, and pH dynamics are key drivers of subsurface biogeochemical cycling and methanogenesis in terrestrial and wetland ecosystems but are typically not included in terrestrial carbon cycle models. These omissions may introduce errors when simulating systems where redox interactions and pH fluctuations are important, such as wetlands where saturation of soils can produce anoxic conditions and coastal systems where sulfate inputs from seawater can influence biogeochemistry. Integrating cycling of redox‐sensitive elements could therefore allow models to better represent key elements of carbon cycling and greenhouse gas production. We describe a model framework that couples the Energy Exascale Earth System Model (E3SM) Land Model (ELM) with PFLOTRAN biogeochemistry, allowing geochemical processes and redox interactions to be integrated with land surface model simulations. We implemented a reaction network including aerobic decomposition, fermentation, sulfate reduction, sulfide oxidation, methanogenesis, and methanotrophy as well as pH dynamics along with iron oxide and iron sulfide mineral precipitation and dissolution. We simulated biogeochemical cycling in tidal wetlands subject to either saltwater or freshwater inputs driven by tidal hydrological dynamics. In simulations with saltwater tidal inputs, sulfate reduction led to accumulation of sulfide, higher dissolved inorganic carbon concentrations, lower dissolved organic carbon concentrations, and lower methane emissions than simulations with freshwater tidal inputs. Model simulations compared well with measured porewater concentrations and surface gas emissions from coastal wetlands in the Northeastern United States. These results demonstrate how simulating geochemical reaction networks can improve land surface model simulations of subsurface biogeochemistry and carbon cycling. Plain Language Summary: Coastal wetlands can store carbon rapidly but are difficult to represent in current models for accurate accounting of how much carbon can be trapped. This difficulty is due to the complex interactions between tides, chemical reactions, and water salinity, which strongly affect the decay of organic matter and the production of greenhouse gases. We enhanced an existing model by linking it to a powerful chemical reaction simulator such that organic matter decomposition was tightly connected to chemical reactions involving key components such as sulfur, iron, oxygen, and methane. We used this model to compute the effect of salinity on organic matter decomposition and greenhouse gas production in saline and freshwater wetlands. The model predicted much lower methane emissions from saltwater‐affected wetlands, which compared well to field measurements from coastal wetland sites in Massachusetts, USA. This model improves the accounting of carbon in wetland ecosystems and opens a broad range of possibilities for representing complex chemistry in land models. Key Points: Coastal wetlands store large amounts of carbon and are sensitive to chemical interactions driven by salinity and tidal fluctuationsWe coupled a land surface model to a reactive transport model to simulate biogeochemical cycling in saline and fresh tidal wetlandsSulfate availability in saline wetlands lowered simulated methane emissions, which compared well with site measurements [ABSTRACT FROM AUTHOR]

Sediment-bound phosphorous fractions were analyzed to assess the bioavailability and trophic status of Thrissur Kole wetlands. Sequential extraction followed by spectrophotometry was employed for fractionation and determination of phosphate content in each fraction. Acid soluble organic phosphorous comprising of biological molecules was the most dominant fraction [278.02 ± 11.82 mg/kg (non-monsoon); 315.77 ± 13.84 mg/kg (monsoon)] recorded during both seasons and can be sourced to allochthonous as well as autochthonous sources. Elevated content of alkali soluble organic phosphorous [162.53 ± 14.85 mg/kg (non-monsoon); 307.22 ± 14.60 mg/kg (monsoon)] reflected leaching of humic-associated phosphorous from aquatic vegetation, domestic and municipal sewage. Enrichment of calcium-bound phosphorous was due to the abundance of calcium carbonate originating through biological precipitation and inputs from guano as well as carcass of birds. Enriched organic matter adsorbed on fine-grained sediments controls the retention of organic phosphorous through organic matter-iron-phosphorous association. Intense microbial reworking on organic matter (substantiated by depleted Eh values) resulted in a sharp decline in organic phosphorous fraction. Adsorption of iron/manganese oxyhydroxides was a prominent mechanism in the retention of phosphate in sediments, endorsed by multivariate statistical analysis. Alkaline pH and reducing environment promote the release of phosphate to the water column and hence bioavailability for phytoplankton uptake. Bioavailable phosphorous constitutes a major portion of total phosphorous [average: 606.86 ± 26.24 mg/kg (non-monsoon); 651.36 ± 23.05 mg/kg (monsoon)], which implied that the wetland sediments can function as a dynamic source of phosphate to the water column, signaling eutrophication risk. [ABSTRACT FROM AUTHOR]

The world's natural wetlands, which have important ecological functions, are being lost at an alarming rate. The erosion and deposition of soil on wetlands is a major cause of wetland conversion to agriculture. An urgent problem to be solved is how to slow down the erosion and deposition of wetlands resulting from land use. Land use patterns affect soil properties, thereby affecting soil aggregate stability and erodibility. Evaluating the effects of land use patterns on soil aggregate stability and erodibility in small watersheds of wetland ecosystems of karst plateau is of great importance. Thus, we compared the soil properties, aggregate stability indicators and soil erodibility of shrubland, grassland, artificial forest land and sloping farmland for evaluating the impact of various land use patterns on soil aggregate stability and erodibility in typical karst plateau wetland ecosystems. Our results showed that the mass fraction of soil aggregates > 0.25 mm was the main component in the four land uses, with greater variation in aggregates > 5 mm; overall, MWD, GMD and WSA0.25 were higher in grassland and shrubland than in sloping farmland and artificial forest land, while K values, PAD and SCAI showed the opposite trend. Correlation analysis showed that effective soil nutrients had a positive effect on soil aggregate stability. In conclusion, the stability of soil aggregates and resistance to soil erosion were strongest under the influence of shrubland. Our study showed that shrubland can better improve soil aggregate stability and erosion resistance, which may provide a guide for protecting and restoring karst plateau wetland ecosystems. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the removal capability of Fe/Al contamination of Indian camphorweed (Pluchea indica; hereafter, P. indica) using different growth substrates (100% sand, gardening soil, vermiculite, and zeolite). In addition, the study aimed at observing the physio-morphological adaptation strategies of P. indica under excess Fe/Al levels in a controlled greenhouse environment. After a 4-week treatment, P. indica plants under excess Fe in the 100% sand substrate exhibited signs of decay and eventually death. In contrast, the growth performances of P. indica under gardening soil substrate remained sustained even when exposed to Fe/Al stress. Under zeolite substrate, Fe in the root tissues was 23.1 and 34.7 mg g–1 DW after 1 and 4 weeks of incubation, respectively. In addition, Al in the root tissues also increased to 1.54 mg g–1 DW after 1 week and 1.59 mg g–1 DW after 4 weeks, when subjected to 20 mM Al treatment. Zeolite was observed to be a promising substrate to regulate the uptake of Fe (3.31 mg plant–1) and Al (0.51 mg plant–1) by the root tissues. The restriction of Fe and Al in the root and a low translocation to the leaf organ was indicated by a low translocation factor (< 1.0). High Fe concentrations in the root and leaf tissues negatively affected root elongation, and the net photosynthetic rate decreased by > 40% compared to positive control. Gas exchange parameters and leaf temperature were found the most sensitive to Fe/Al stress. Moreover, the limited transpiration rate under Fe/Al stress caused an increase of the leaf temperature and crop stress index. The findings suggest that P. indica grown using zeolite substrate may serve as a good model system for constructed wetlands, storing excess Al in the root tissues without any significant growth inhibition. [ABSTRACT FROM AUTHOR]

The evaluation of Hadejia-Nguru wetland soils was carried out for two consecutive dry seasons. Standard analytical techniques were adopted to analyze the samples and statistical models were used to assess the spatial and temporal distribution of the parameters selected. The average pH values of the soil samples were mostly alkaline, and all the measured values were also within the approved standards. Experimental results revealed a significantly positive correlation between Ca and Mg for both seasons as indicated by the p-values and a high coefficient of determination (R2) for both metals with cation exchange capacity (CEC) values as the predictors. The regression analysis showed that the changes in CEC and pH levels in the soil were dependent on changes in Ca and Mg content of the soil. The data obtained showed that the increase in pH is directly proportional to the CEC and base saturation of the soils. A higher percentage of Ca than other cations (Mg, K and Na) was observed from the base saturation of the soils. The pH, base saturation, and CEC levels in the soils are suitable for most crops grown in the area, which has the potential to support a wide range of crops with further exploration. HIGHLIGHTS The physicochemical characteristics of Hadejia-Nguru wetlands soils were investigated.; Statistical models were used to assess the spatial and temporal distribution of the parameters.; Metals play a crucial role in determining the soil quality.; Investigations indicated that the study area is suitable for the farming of vegetables and cereal crops.;

Soil enzymes play a central role in carbon and nutrient cycling, and their activities can be affected by drought-induced oxygen exposure. However, a systematic global estimate of enzyme sensitivity to drought in wetlands is still lacking. Through a meta-analysis of 55 studies comprising 761 paired observations, this study found that phosphorus-related enzyme activity increased by 38% as result of drought in wetlands, while the majority of other soil enzyme activities remained stable. The expansion of vascular plants under long-term drought significantly promoted the accumulation of phenolic compounds. Using a 2-week incubation experiment with phenol supplementation, we found that phosphorus-related enzyme could tolerate higher biotoxicity of phenolic compounds than other enzymes. Moreover, a long-term (35 years) drainage experiment in a northern peatland in China confirmed that the increased phenolic concentration in surface layer resulting from a shift in vegetation composition inhibited the increase in enzyme activities caused by rising oxygen availability, except for phosphorus-related enzyme. Overall, these results demonstrate the complex and resilient nature of wetland ecosystems, with soil enzymes showing a high degree of adaptation to drought conditions. These new insights could help evaluate the impact of drought on future wetland ecosystem services and provide a theoretical foundation for the remediation of degraded wetlands. [ABSTRACT FROM AUTHOR]

Currently, carbon-based substances are widely used in agriculture and industry, leading to obvious accumulation in ecosystems. Natural ecosystems, especially water-logged areas, are important sources of greenhouse gases. However, it is not clear whether the dimensions of carbon-based substances can affect their emission. Herein, the effects of three kinds of carbon-based substances (including carbon nanotubes, graphene, and graphite powder) with dimensions from one to three on the CO2 and CH4 production potential were tested from a saltmarsh wetland soil. Carbon nanotubes inhibited CH4 production, and graphene showed slight inhibition. In contrast, graphite powder could promote methanogenesis, and the maximum CH4 concentration was 53.02 mmol g−1 L−1. With a decrease, the maximum CH4 concentration with carbon nanotubes was only 38.09 mmol g−1 L−1. Interestingly, the effect of carbon-based substances on CO2 production was opposite to that on CH4. Carbon nanotubes showed the greatest promotion effect on CO2 production. In addition, by comparing the effects of carbon-based substances on global warming equivalent, graphite powder showed a promotion effect compared with the control, while carbon nanotubes decreased it. This study provides basic data for understanding the effects of carbon-based substances with diverse dimensions on greenhouse gas dynamics in saltmarsh wetland soil. [ABSTRACT FROM AUTHOR]

This study is carried out to understand the degree of soil pollution, transport mechanism, and distribution pattern of potentially toxic elements (PTEs), including the exposure effects on human health. Towards this, topsoil samples were collected from the Saman wetland and surrounding agricultural fields in the Gangetic plain, India. The results show that the mean concentration of Cu, Hg, Zn, Pb, Th, As, U, and Cd of both soil types exceed the natural background values. The multivariate analysis suggests the soils are moderately contaminated with As, Cd, Zn, Pb, and Hg (possibly from anthropogenic sources) and heavily contaminated with Th and U, likely ascended from geogenic sources. The GIS-based geostatistical plots coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) apportion the sources of these toxic elements, which vary greatly and are closely correlated to the geogenic processes and local anthropogenic sources like pesticides and agrochemicals. The health risk assessment revealed that the cumulative hazard index (HI) values of PTEs are lower than the safe level, suggesting no significant noncarcinogenic effect for adults and children. However, excess cancer risk (ECR) values exceed the permissible limit (1 × 10−6), signifying that exposure to the toxic element concentration may cause cancer in the exposed population, most probably in the children subpopulation. Thus, this study highlights the importance of local compliance, ensuring the quality checks and management policies in using pesticides and other agrochemicals containing PTEs to control the imposed cancer risks. [ABSTRACT FROM AUTHOR]

Information about species distributions is lacking in many regions of the world, forcing resource managers to answer complex ecological questions with incomplete data. Information gaps are compounded by climate change, driving ecological bottlenecks that can act as new demographic constraints on fauna. Here, we construct greater sandhill crane (Antigone canadensis tabida) summering range in western North America using movement data from 120 GPS‐tagged individuals to determine how landscape composition shaped their distributions. Landscape variables developed from remotely sensed data were combined with bird locations to model distribution probabilities. Additionally, land‐use and ownership were summarized within summer range as a measure of general bird use. Wetland variables identified as important predictors of bird distributions were evaluated in a post hoc analysis to measure long‐term (1984–2022) effects of climate‐driven surface water drying. Wetlands and associated agricultural practices accounted for 1.2% of summer range but were key predictors of occurrence. Bird distributions were structured by riparian floodplains that concentrated wetlands, and flood‐irrigated agriculture in otherwise arid and semi‐arid landscapes. Findings highlighted the role of private lands in greater sandhill crane ecology as they accounted for 78% of predicted distributions. Wetland drying observed in portions of the range from 1984 to 2022 represented an emerging ecological bottleneck that could limit future greater sandhill crane summer range. Study outcomes provide novel insight into the significance of ecosystem services provided by flood‐irrigated agriculture that supported nearly 60% of wetland resources used by birds. Findings suggest greater sandhill cranes function as a surrogate species for agroecology and climate change adaptation strategies seeking to reduce agricultural water use through improved efficiency while also maintaining distinct flood‐irrigation practices supporting greater sandhill cranes and other wetland‐dependent wildlife. We make our wetland and sandhill crane summering distributions available as interactive web‐based mapping tools to inform conservation design. [ABSTRACT FROM AUTHOR]

For the first time, data on the emission of climate-active gases from soils of different types of use of the south taiga sub-zone were obtained. Soils of the boreal belt are key elements of the global carbon cycle. They determine the sink and emission of climate-active gases. Soils near large cities are a major carbon sink, in the face of climate change, soils from sinks can become a source of carbon and contribute significantly to climate change on the planet. Studies of FCO2 and FCH4 fluxes were carried out on the territory of the monitoring site "Ladoga" located in the southern taiga subzone in soils of land not used in agriculture, former agriculture lands, and wetlands. During the chamber measurements, a portable gas analyzer GLA131-GGA (ABB, Canada) was used. The chamber was placed on the soil, after which the concentration of CO2, CH4 and H2O in the mobile chamber was recorded. As a result of the study it was found that the lowest emission of carbon dioxide is characteristic of soils developing on the soils of wetland and is 0.64 gCO2/(m2*year). Which is associated with a high degree of hydrophobicity of the territory and changes in the redox regime. The highest emission of carbon dioxide is registered in soils on the land not used in agriculture and is 4.16 gCO2/(m2*year). This is due to the formation of predominantly labile forms of carbon in the soil, which can be relatively rapidly involved in the carbon cycle and affect the active emission of carbon from the soil. According to the data obtained on FCH4 emission from soils, it was found that soils of land not used in agriculture and former agriculture lands were net sinks, while soils of wetlands were characterized by CH4 source, the emission was from 0.05 to 0.83 gCH4/(m2*year). The results obtained indicate spatial heterogeneity and changes in the carbon cycle within the monitoring site "Ladoga", which are due to the change of plant communities and habitat type. Monitoring the release of important greenhouse gases in close proximity to major urban areas is an important task in the face of predicted climate change and increasing rates of urbanization. [ABSTRACT FROM AUTHOR]

Growing season temperatures play a crucial role in controlling treeline elevation at regional to global scales. However, understanding of treeline dynamics in response to long-term changes in temperature is limited. In this study, we analyze pollen, plant macrofossils, and charcoal preserved in organic layers within a 10,400-year-old ice patch and in sediment from a 6000-year-old wetland located above present-day treeline in the Beartooth Mountains, Wyoming, to explore the relationship between Holocene climate variability and shifts in treeline elevation. Pollen data indicate a lower-than-present treeline between 9000 and 6200 cal yr BP during the warm, dry summer and cold winter conditions of the early Holocene. Increases in arboreal pollen at 6200 cal yr BP suggest an upslope treeline expansion when summers became cooler and wetter. A possible hiatus in the wetland record at ca. 4200–3000 cal yr BP suggests increased snow and ice cover at high elevations and a lowering of treeline. Treeline position continued to fluctuate with growing season warming and cooling during the late-Holocene. Periods of high fire activity correspond with times of increased woody cover at high elevations. The two records indicate that climate was an important driver of vegetation and treeline change during the Holocene. Early Holocene treeline was governed by moisture limitations, whereas late-Holocene treeline was sensitive to increases in growing season temperatures. Climate projections for the region suggest warmer temperatures could decrease effective growing season moisture at high elevations resulting in a reduction of treeline elevation. [ABSTRACT FROM AUTHOR]

Stream, floodplain, and wetland restorations enhance water quality and ecological function; however, soil health is prioritized infrequently in restoration planning and monitoring. Buried, historic, hydric soils—common across U.S. mid‐Atlantic valley bottoms beneath legacy sediments—are not included in most floodplain restoration designs, though they may retain favorable biogeochemical characteristics and host legacy microbial communities that could support ecosystem recovery if exhumed and preserved. To assess the efficacy of including historic hydric soils in floodplain restoration for nitrogen (N) removal, we characterized pre‐Euro‐American settlement wetland soils buried below legacy sediments and now exposed along incised streambanks across the mid‐Atlantic. We compared carbon (C) and N contents; C:N ratios; nitrate‐N and ammonium‐N concentrations; denitrification rates; functional genes for denitrification (nosZ) and nitrification (amoA for ammonia oxidizing archaea [AoA] + ammonia oxidizing bacteria [AoB]); and phospholipid fatty acid biomasses of historic wetland soils with contemporary wetland soils before and after an 1‐year incubation in a recently restored floodplain. Compared to modern wetland soils, historic hydric soils buried by legacy sediment are less nutrient‐rich, have fewer functional genes for and lower rates of denitrification, and possess significantly less microbial biomass. Following the 1‐year incubation, many of these concentrations, rates, and gene counts increased in historic soils, though not substantially. Ultimately, our results suggest that while inclusion of historic, hydric soils and their legacy microbiomes is valuable for N‐removal in floodplain restoration, the recovery of historic, hydric soils is predictably slow, and attainment of restoration goals, such as increased denitrification, may require multiple years. [ABSTRACT FROM AUTHOR]

Microorganisms play important roles in soil biogeochemical processes, but the relative contributions of different microbial members in soil nutrient cycling and community maintenance are unclear especially in wetland soils with water‐level fluctuation. Here, soil samples, collected from severe inundation zone (SIZ), wet–dry cycling zone (WIZ), and arid zone (NIZ) of the lakeshore wetland of plateau lake Caohai, were used to investigate the relative contributions of core and rare taxa in maintaining nutrient cycling and their associations with microbial network. Results showed that WIZ exhibited higher extracellular enzyme activities including β‐1,4‐N‐acetylglucosaminidase, L‐leucine aminopeptidase, and acid phosphatase, the level of multi‐nutrient cycling and core microbial diversity compared with the NIZ and SIZ. The values of topological features (i.e., links, average degree, clustering coefficient, and graph density) were also higher in the WIZ compared with the NIZ and SIZ. Moreover, the core taxa, specifically their community structures, were the most important driver for multi‐nutrient cycles of wetland soil. Among these taxa, Sphingomonas, Bradyrhizobium, Mortierella, and Fusarium as the most abundant taxa in lakeshore wetlands were significantly positively correlated with most extracellular enzymes. By contrast, rare taxa showed higher degree and its subnetwork complexity than those of core taxa, which potentially serve as the species pool of core taxa to maintaining the microbial community stability. In conclusion, our study suggested that core taxa play dominant roles in soil nutrient cycles, while rare microbiota could greatly influence microbial interaction under hydrological changes. [ABSTRACT FROM AUTHOR]

Despite frequent detection in environmental waters, literature which quantifies the health risk of silver nanoparticles (Ag NPs) through oral ingestion is scarce. This study compiled literature data to find the removal of Ag NPs from different treatment schemes (i.e., natural, engineered, or hybrid). Ag NP concentrations were found either in surface water or in groundwater based on where the effluent of treatment schemes was discharged, i.e., either in surface water or in groundwater. Monte-Carlo simulation was carried out for probabilistic assessment of health risks for children for two hypothetical exposure scenarios: (a) ingesting river water while swimming and (b) drinking groundwater. Bio-accessible fraction, dietary metal adsorption factor, and concentrations of silver ions were incorporated to simulate realistic situations. Different treatment schemes were ranked for their nanoparticles' removal efficiency with respect to (i) exceedance probability from guideline value and (ii) health risk to children. Hybrid treatment combinations, i.e., conventional primary and secondary treatment units followed by nature-based units (constructed wetlands and soil aquifer treatment), were ranked the best. The health risk value was found to be less than 1, with the 99th percentile value less than 10−3 in all cases. The maximum allowable concentration of Ag NPs was found to be as low as 1.43 mg/L for groundwater, suggesting probable potential for risk. Uncertainty analysis revealed that the uncertainty of the influent NPs concentration in raw wastewater contributes > 99% to the variance of the hazard index. The results of this work indicate that the use of natural treatment technologies with existing engineered treatments provides higher nanoparticle removal from wastewater without the requirement of any tertiary treatment unit. [ABSTRACT FROM AUTHOR]

• OsPDR20 is induced by Cd and localized to the plasma membrane. • Knockdown of OsPDR20 compromised rice growth and development. • Knockdown of OsPDR20 led to accumulated Cd in rice. • Developing OsPDR20 genotype is critical for phytoremediation of Cd-polluted wetland soils. Cadmium (Cd) is a non-essential toxic heavy metal, seriously posing high environmental risks to human health. Digging genetic resources relevant to functional genes is important for understanding the metal absorption and accumulation in crops and bioremediation of Cd-polluted environments. This study investigated a functionally uncharacterized ATP binding cassette transporter G family (ABCG) gene encoding a Pleiotropic Drug Resistance 20 (PDR20) type metal transporter which is localized to the plasma membrane of rice. OsPDR20 was transcriptionally expressed in almost all tissues and organs in lifespan and was strongly induced in roots and shoots of young rice under Cd stress. Ectopic expression of OsPDR20 in a yeast mutant ycf1 sensitive to Cd conferred cellular tolerance with less Cd accumulation. Knockdown of OsPDR20 by RNA interference (RNAi) moderately attenuated root/shoot elongation and biomass, with reduced chlorophylls in rice grown under hydroponic medium with 2 and 10 µmol/L Cd, but led to more Cd accumulation. A field trial of rice grown in a realistic Cd-contaminated soil (0.40 mg/kg) showed that RNAi plants growth and development were also compromised compared to wild-type (WT), with smaller panicles and lower spikelet fertility but little effect on yield of grains. However, OsPDR20 suppression resulted in unexpectedly higher levels of Cd accumulation in rice straw including lower leaves and culm and grain. These results suggest that OsPDR20 is actively involved in Cd accumulation and homeostasis in rice crops. The increased Cd accumulation in the RNAi plants has the potential application in phytoremediation of Cd-polluted wetland soils. [Display omitted] [ABSTRACT FROM AUTHOR]

This research investigates the capability of hydrological site design to mitigate inland flooding. Empirical data for a target watershed characterize interaction among three hydrologic components: stormwater detention ponds; seasonal wetlands; and soils/groundwater. Findings are (a) stormwater ponds' elevation change in response to precipitation events of a given magnitude varies sharply among storms, such that ponds' pre‐event elevation and forecast precipitation are not reliable to predict ponds' ability to detain runoff sufficiently to avoid downstream flooding; (b) water table elevation is governed partly by long‐term seasonal variation but also responds quickly to specific events, and powerfully affects the system's capacity to detain runoff; (c) water table elevation during wet weather periods common to Southwest Florida can be high enough to breach the soil surface for extended periods, severely reducing the capacity of the system to detain runoff; (d) in the target watershed of the Florida Gulf Coast University campus, depressed surface storage in seasonal wetlands compensates for reduced wet season capacity of ponds and soil storage. That mechanism explains why the campus has successfully mitigated flooding including from high‐precipitation events most prone to produce flooding (intense rate, late wet season events), while some downstream communities with components designed to meet the regulatory minimum have experienced inundation. [ABSTRACT FROM AUTHOR]

Background: The introduction of multiple avian influenza virus (AIV) subtypes into Nigeria has resulted in several poultry outbreaks purportedly linked to trade and wild birds. The role of wild birds in perpetuating AIV in Nigeria was, therefore, elucidated. Methods: A cross‐sectional study was conducted among wild aquatic bird species at the Hadejia‐Nguru wetlands in Northeastern Nigeria between March and April 2022. A total of 452 swabs (226 cloacae and 226 oropharyngeal) were collected using a mist net to capture the birds. These samples were tested by RT‐qPCR, followed by sequencing. Results: Highly pathogenic AIV of the H5N1 subtype was identified in clinically healthy wild bird species, namely, African jacana, ruff, spur‐winged goose, squared‐tailed nightjar, white‐faced whistling ducks, and white stork. A prevalence of 11.1% (25/226) was recorded. Phylogenetic analysis of the complete HA gene segment indicated the presence of clade 2.3.4.4b. However, these H5N1 viruses characterized from these wild birds cluster separately from the H5N1 viruses characterized in Nigerian poultry since early 2021. Specifically, the viruses form two distinct genetic groups both linked with the Eurasian H5N1 gene pool but likely resulting from two distinct introductions of the virus in the region. Whole‐genome characterization of the viruses reveals the presence of mammalian adaptive marker E627K in two Afro‐tropical resident aquatic ducks. This has zoonotic potential. Conclusion: Our findings highlight the key role of surveillance in wild birds to monitor the diversity of viruses in this area, provide the foundations of epidemiological understanding, and facilitate risk assessment. [ABSTRACT FROM AUTHOR]

Diverse influenza A viruses (IAVs) circulate in wild birds, including highly pathogenic strains that infect poultry and humans. Consequently, surveillance of IAVs in wild birds is a cornerstone of agricultural biosecurity and pandemic preparedness. Surveillance is traditionally done by testing wild birds directly, but obtaining these specimens is labor intensive, detection rates can be low, and sampling is often biased toward certain avian species. As a result, local incursions of dangerous IAVs are rarely detected before outbreaks begin. Testing environmental specimens from wild bird habitats has been proposed as an alternative surveillance strategy. These specimens are thought to contain diverse IAVs deposited by a broad range of avian hosts, including species that are not typically sampled by surveillance programs. To enable this surveillance strategy, we developed a targeted genomic sequencing method for characterizing IAVs in these challenging environmental specimens. It combines custom hybridization probes, unique molecular index-based library construction, and purpose-built bioinformatic tools, allowing IAV genomic material to be enriched and analyzed with single-fragment resolution. We demonstrated our method on 90 sediment specimens from wetlands around Vancouver, Canada. We recovered 2,312 IAV genome fragments originating from all eight IAV genome segments. Eleven hemagglutinin subtypes and nine neuraminidase subtypes were detected, including H5, the current global surveillance priority. Our results demonstrate that targeted genomic sequencing of environmental specimens from wild bird habitats could become a valuable complement to avian influenza surveillance programs. [ABSTRACT FROM AUTHOR]