Journal of Environmental Management最新文献

Nitrogen (N) pollution has emerged as a critical environmental issue hindering the sustainable development of global aquatic ecosystems in the 21st century. Particularly, N accumulation in aquaculture water has become a major pollutant, severely restricting the green and healthy development of aquaculture. Here, two efficient and safe heterotrophic nitrification-aerobic denitrification (HN-AD) strains were isolated from shrimp aquaculture environments and identified as Yanghufangia pacifica HHVEN1 and Glutamicibacter nicotianae SDVEA2. Under single or mixed inorganic-N conditions, both strains achieved >82.29% removal of ammonia-N (NH₄⁺-N) and nitrite-N (NO₂^--N), and maintained high performance across a wide range of temperature, pH, salinity, and C/N ratio. Notably, HHVEN1 completely removed NH₄⁺-N within 18 h, whereas SDVEA2 showed particularly strong nitrate removal (99.43% within 36 h). Based on time-course profiles of N species, N-removal functional genes, enzyme activities, and inhibitor assays, HHVEN1 predominantly followed a canonical HN-AD route and showed evidence for an ammonia-to-nitrate shortcut and a potential direct ammonium-to-gaseous-N conversion. In contrast, SDVEA2 mainly converted ammonium via nitrate and nitrite to gaseous N and reduced nitrate to gaseous N, despite lacking detectable canonical amoA, hao, and nxr genes. Haldane kinetic models were fitted to describe the relationships between substrate concentration and growth/N removal, indicating adaptation to medium-low N levels. Using response surface methodology (RSM), a multi-factor coupling model linking salinity, N sources and inoculum size was established, and a calculation method for optimal inoculum in dynamic aquatic scenarios was proposed. This study provides scientific support for N pollution control in aquaculture and related aquatic environments.

Grazing influences the spatial and temporal dynamics of vegetation heterogeneity and structure. Whether due to intensification or abandonment, changes in grazing dynamics may cause a variety of habitat responses at different spatio-temporal scales that significantly influence ecological communities. Despite extensive knowledge on the effects of grazing on mountain ecosystems, there is still a limited understanding of how different grazing histories and their legacy (i.e. past long-term effects) interact to shape biodiversity across broad spatial gradients. We aimed to identify the optimal stage of vegetation conditions resulting from particular grazing dynamics and their legacy effects that would maximise butterfly and plant biodiversity across a large geographical range in the Pyrenees. We sought to assess how grazing (either through legacies or immediate effects) influences the richness, abundance, community composition and functional group structure of both plant and butterfly species. We conducted butterfly and plant surveys in 60-x-60m plots in 12 valleys in the Catalan Pyrenees (western Mediterranean) under four different grazing legacy regimes representing different vegetation conditions, ranging from heavily grazed grasslands to densely scrub-encroached areas. We also conducted participatory mapping with local cattle-herders to gain insights into the spatial-temporal dynamics of the grazing legacy regimes. Intermediate grazing stages exhibited significantly higher plant and butterfly richness and abundance, and also harboured species of greater conservation concern. Grazing legacy was the main driver for butterfly and plant diversity, community composition and functionality. Maintaining low to medium grazing intensity is essential for preserving vegetation heterogeneity and enhancing both butterfly and plant richness and abundance.

Extreme droughts threaten ecosystem functions, stability, and health. Understanding the key regulatory mechanisms of ecosystem resistance to such droughts is crucial for safeguarding ecological health and optimizing resource management. Previous studies focused on horizontal-scale biodiversity's impact on drought resistance, with little attention to vertical structural complexity. Taking the 2022 summer extreme drought in the Yangtze River Basin (YZRB) as a case, we evaluated drought resistance and underlying regulatory mechanisms across ecosystems with different vertical structural diversity. We used a set of indicators including vegetation indices, foliage height diversity (vertical structural complexity), water use efficiency (WUE), and soil nutrient indices. Results showed 76.46% of the basin was affected, with 30.36% experiencing the most severe drought. Three vegetation indices exhibited similar spatial response patterns, declining by 5.20-6.77% in 2022 (vs. 2021) in drought-affected areas. The basin's median resistance was approximately 32.18, peaking in the severely affected middle and lower reaches. Forests showed the highest resistance, with significant differences among ecosystem types. Vertical structural complexity correlated positively with resistance (p < 0.05) and strongly with WUE (p < 0.01), indicating it enhances WUE. Random forest and structural equation models further revealed vertical structural complexity improves drought resistance mainly by positively regulating WUE. Soil nutrients directly and indirectly (via vertical structure and WUE) regulate resistance. This highlights the need to incorporate vertical structural complexity alongside horizontal biodiversity in assessing ecosystem stability under climate extremes. Overall, our study advances understanding of ecosystem drought response mechanisms via vertical structural complexity, WUE, and soil nutrition, supporting regional ecological health maintenance and management.

More frequent episodes of extreme rainfall and increasing impervious surfaces are expected to intensify the need to finance nature-based solutions for stormwater management (stormwater NbS) in cities. This study conducted a systematic literature mapping and scoping review to examine i) how the literature on stormwater NbS financing mechanisms has evolved, ii) which types of stormwater NbS financing mechanisms are most commonly reported and whether new mechanisms are emerging, and iii) whether geographical differences exist in their application. We find that publications on stormwater NbS financing mechanisms increase from around 2010 onwards, peaked in 2019, and declined afterwards. Our assessment distinguishes two main types of mechanisms: financing mechanisms used by local governments (FMLG) and financing mechanisms used to encourage third parties (FMETP), which are reported to approximately equal proportions in the literature. For FMLG, "instruments generating revenue" are most frequently reported (N = 69), followed by grant funding and donations (N = 35). Examples of "green finance or debt-based instruments" were identified 19 times, while the use of public budgets was reported 12 times. For FMETP, "market-based instruments" clearly dominate (N = 121), with subsidies (n = 59) and tax or fee rebates (n = 43) being the most prominent mechanisms. Geographically, the use of stormwater NbS financing mechanisms is unevenly distributed around the globe, with a clear dominance of cases reported from North America (FMLG = 120, FMETP = 129), particularly the United States (FMLG = 114, FMETP = 123), followed by Europe (FMLG = 27, FMETP = 32) and Asia (FMLG = 16, FMETP = 15). Stormwater NbS financing mechanisms are nearly absent in South America and Africa. Most mechanisms focus on financing the implementation of new stormwater NbS, while only a minority address operation and maintenance costs. Our review also reveals promising complementary management approaches used in combination with financing mechanisms, as well as more advanced instruments such as performance-based contracts, which may have broader application in the future. Future research could focus on mechanisms for financing operation and maintenance, the transferability of financing approaches across contexts, and the effectiveness and limitations of different FMLGs and FMETPs, including their combination with complementary management measures.

As representative landscape water bodies, urban park ponds are typically shallow and hydrologically isolated, making them highly susceptible to algal blooms. This study focused on recurrent summer-autumn blooms of Euglena sanguinea in Hefei Binhu Forest Park. These blooms form thin, red, oil-slick-like surface scums that severely suppress aquatic photosynthesis. We investigated phytoplankton community succession and its drivers by collecting surface biofilm, mid-depth water, and bottom sediment samples from three representative ponds during the 2024 bloom season. Results revealed extensive E. sanguinea blooms in July-August, with surface cell density reaching 9.86 × 10⁶ cells/L (42% of total) and biomass attaining 98.61 mg/L (94% of total). This bloom peak coincided with a 2.5-fold increase in surface dissolved total nitrogen (DTN) and phosphorus (DTP). Concurrently, the surface biofilm exhibited a peak extracellular polymeric substance (EPS) concentration of 43.92 mg/L and a film-forming rate of 90.73%, structurally supported by the predominance of large algal-bacterial aggregates (>64 μm), which accounted for nearly 80% of the particulate composition. The bounding EPS (BEPS), rich in tryptophan-like proteins, corresponded with peak biofilm hydrophobicity. Critically, this nutrient-enriched microenvironmental transformation selected for a low-diversity, high-dominance microbiome. Burkholderiaceae dominated the August biofilm (23%), contrasting sharply with sediment communities (dominated by Steroidobacteraceae, 7%) and post-bloom October biofilms (dominated by Sporichthyaceae, 21%). Mechanistic path analysis revealed that DTN and DTP stimulated bloom expansion not by directly promoting algae, but by enriching Burkholderiaceae and stimulating EPS production. These findings elucidate a microbially mediated pathway linking nutrient enrichment to E. sanguinea bloom formation, challenging the conventional direct nutrient-bloom paradigm. The study provides mechanistic blueprint for targeted, microbiome-informed management of urban landscape water blooms.

Wetlands are recognized as threatened habitats in Europe, having largely disappeared globally because of ongoing anthropogenic pressures. Particularly, temporary ponds are priority habitats for conservation in the Mediterranean region, yet they require urgent actions due to their vulnerability to climate change and external perturbations. However, large-scale impacts of agricultural intensification and climate effects on temporary ponds remains poorly understood, as their small size and shallow depth make them particularly challenging to monitor using remote sensing techniques. In peninsular Spain, we assessed (1) the legal protection status of 1303 ponds from 193 bibliographic, and public sources, quantifying overlaps between the Natura 2000 network (N2K) and other Protected Areas (PAs), (2) how protection status influences the occurrence of visible anthropogenic impacts, and (3) recent trends in water occurrence by modelling climatic variables and these anthropogenic impacts. Google Earth Pro imagery was used to record the presence of surface water and these impacts. Our results revealed substantial overlap between N2K and other PAs. N2K alone was less effective in mitigating agricultural impacts. Ponds under overlapping designations of N2K and other PAs showed lower prevalence of impacts. Agriculture-related impacts-i.e. ploughed borders, ploughed basin, and channelling-were the most widespread and associated with pond disappearance among visually observable impacts. Ploughed basin, channelling, and climatic drivers altered pond hydroperiods and accelerated habitat loss. These findings highlight the importance of effective protection, underscoring the urgent need to strengthen management within existing PAs, expand conservation to unprotected ponds, and integrate cost-effective monitoring for early detection of degradation.

Forests are vital global carbon sinks and provide critical ecosystem services for soil conservation. Reforestation is a critical strategy for mitigating land degradation, yet prioritizing areas for restoration to maximize erosion control at the watershed level remains a key challenge in environmental management. This study introduces a novel spatial optimization framework that integrates the Unit Stream Power Erosion Deposition (USPED) model with a Genetic Algorithm (GA) to guide reforestation planning in the Seridó River Basin, within Brazil's semi-arid Caatinga biome. Our objective was to identify an optimal forest cover configuration that minimizes soil loss. The optimized scenario increased forest cover by 20%, reducing gross soil loss from 105,000 to 75,000 tons per year. The extent of stable areas increased from 39.48% to 43.07%, and areas under extreme erosion risk were significantly reduced. Landscape pattern analysis revealed a trade-off: the Landscape Shape Index increased from 245.80 to 307.20, indicating more complex forest fragments, while the Contagion Index showed stable connectivity. The findings confirm that the strategic spatial allocation of forests is more critical than simply expanding cover. The proposed heuristic-based spatial optimization framework provides land managers and policymakers with a powerful, data-driven tool for designing targeted reforestation interventions that effectively enhance soil conservation and ecosystem service provision in vulnerable dry forest ecosystems.

Soil lead (Pb) contamination poses a significant global threat to both ecological safety and human health. While conventional immobilizing agents effectively reduce Pb mobility, they exhibit inherent limitations, necessitating the development of novel remediation materials. Furthermore, the remediation efficacy of these agents remains inadequately characterized, as comprehensive evaluations-particularly those assessing the reduction of human health risks via oral ingestion-are frequently omitted. In this comparative study, three types of immobilizing agents, namely, the conventional KH₂PO₄ and Ca(OH)₂, and the promising CaAl-Layered double hydroxide (LDH), were applied to remediate five typical Pb-contaminated soil types in China: red, cinnamon, black, brown, and yellow soils. The remediation efficacy was comprehensively evaluated in terms of the migration factor, ecological risk, and human health risk of soil Pb. The results indicated that at their respective optimal application rates, KH₂PO₄, Ca(OH)₂, and CaAl-LDH significantly reduced the migration factor of soil Pb by averages of 66.7%, 16.1%, and 56.0%, respectively. Furthermore, the leachability and relevant ecological risk associated with soil Pb were reduced by 93.2%, 93.7%, and 56.3%, respectively. Notably, CaAl-LDH exhibited superior performance in mitigating Pb bioaccessibility and relevant human health risk, with average reductions of 42.1% and 48.6% in the gastric and small intestinal phases, respectively. The reduction efficacy of CaAl-LDH in the gastric and small intestinal phases was 4.21 and 3.90 times and 2.17 and 1.17 times that of KH₂PO₄ and Ca(OH)₂, respectively. These results demonstrate the effectiveness of CaAl-LDH for Pb immobilization and its potential for field-scale application. This study provides a scientific foundation for the research and development of highly efficient immobilization agents for Pb-contaminated soils and the improvement of eco-environmental quality and human health.

Trees are the ultimate solution for local climate mitigation; however, their direct transpirational cooling (TC) effects vary across global regions, primarily affected by hydroclimatic conditions and tree traits. Although vegetation biophysical effects are examined by modelling and satellite remote sensing in some regions, yet, the global-scale synthesis of trees' TC dynamics remains underexplored by ground observations. We used the SAPFLUXNET database and evapotranspiration (from GLEAM) to compare trees' TC effects across global regions in response to hydroclimatic and biotic variables. We found that trees provide significant cooling, with air temperature reduction (ΔT) of 3.25 °C m^-2 d^-1 in warm-wet regions of Central and South America (C/SAM), while the lowest cooling, with ΔT of 0.46 and 0.26 °C m^-2 d^-1 in hot-dry regions of Africa (AF) and Central and East Asia (C/EA), respectively. This can be explained by an increase in leaf area index (LAI) and ample soil water content (SWC) in warm-wet regions, whereas trees in hot-dry regions remain less effective in cooling due to low LAI and aridity. This study uniquely characterizes the nonlinear connection between ΔT and hydroclimatic and biotic factors, highlighting that biotic factors have more impact on the dynamics of daily mean ΔT, followed by hydroclimatic factors. Additionally, region-specific changes in TC are attributable to ΔT's increased sensitivity to air temperature and vapor pressure deficit in warm-wet regions, and precipitation and SWC in hot-dry regions, primarily controlled by stomatal regulation. These findings offer critical insights into the importance of considering trees' biophysical effects when designing local climate mitigation and adaptation strategies.

Reservoir drawdown zones, the seasonally exposed and re-flooded margins of reservoirs, are extensive pulsed wetlands that can act as hotspots of greenhouse gas (GHG) exchange. Vegetation harvesting is common in these zones, yet its net climate effect across CO₂, CH₄, and N₂O, and the controls behind it, remain unclear. We compared harvested and unharvested plots across longitudinal river reaches and elevation bands in the drawdown zone of the Three Gorges Reservoir (China). We measured soil-atmosphere fluxes of CO₂, CH₄, and N₂O, together with soil physicochemical properties and metagenome-derived functional markers. Harvesting increased CO₂ flux and decreased CH₄ flux, while N₂O showed no detectable net treatment effect. Across analyses, soil hydrothermal and nutrient conditions were the dominant predictors of flux variation; microbial functional signals added information mainly through soil-dependent interactions. In CO₂-equivalent terms, lower CH₄ emissions only partly compensated for higher CO₂, leaving a net positive effect under both 20- and 100-year horizons. These results underscore that harvest impacts in drawdown soils should be assessed as multi-gas trade-offs and interpreted through soil moisture-redox dynamics.