Agricultural drainage water continues to impact watersheds and their receiving water bodies. One approach to mitigate this problem is to use surrounding natural wetlands. Our objectives were to determine the effect of iron (Fe)-rich groundwater on phosphorus (P) removal and nutrient absorption by the utilization of the iron plaque on the root surface of Glyceria spiculosa (Fr. Schmidt.) Rosh. The experiment was comprised of two main factors with three regimes: Fe²⁺ (0, 1, 20, 100, 500 mg·L⁻¹) and P (0.01, 0.1, 0.5 mg·L⁻¹). The deposition and structure of iron plaque was examined through a scanning electron microscope and energy-dispersive X-ray analyzer. Iron could, however, also impose toxic effects on the biota. We therefore provide the scanning electron microscopy (SEM) on iron plaques, showing the essential elements were iron (Fe), oxygen (O), aluminum (Al), manganese (Mn), P, and sulphur (S). Results showed that (1) Iron plaque increased with increasing Fe²⁺ supply, and P-deficiency promoted its formation; (2) Depending on the amount of iron plaque on roots, nutrient uptake was enhanced at low levels, but at higher levels, it inhibited element accumulation and translocation; (3) The absorption of manganese was particularly affected by iron plague, which also enhanced phosphorus uptake until the external iron concentration exceeded 100 mg·L⁻¹. Therefore, the presence of iron plaque on the root surface would increase the uptake of P, which depends on the concentration of iron-rich groundwater.

Soil microbial communities are vital for saline-alkaline ecosystem functioning; however, their succession during land degradation and their influence on phosphorus (P) transformation remain unclear. To address this gap, this study investigated the dynamics of soil microbial communities and P fractions along a degradation gradient from native grassland to Suaeda salsa vegetation and ultimately to bare land in the Songnen Plain, China. The results revealed that progressive saline-alkaline degradation significantly altered soil properties, increased the proportion of stable P fractions, and reduced microbial alpha diversity. Network analysis revealed that bacterial communities shifted from competition to cooperation along the salinity–alkalinity degradation gradient, indicating a cooperative strategy to cope with environmental stress. Fungal networks exhibit progressively reduced complexity and stability with increasing degradation. Partial least squares path modeling confirmed that soil pH and electrical conductivity directly and indirectly regulated P fractions by reshaping microbial communities, with bacteria exhibiting a stronger total effect than fungi. In conclusion, saline-alkaline degradation drives microbial community succession, which mediates the transformation of soil P into more stable forms and exacerbates P limitation. This study provides a scientific basis for targeted restoration and sustainable management of saline-alkaline ecosystems.

Introduction: Microorganisms regulate nutrient cycling and ecosystem stability in saline–alkali ecosystems. However, their adaptation mechanisms and metabolic functions to saline–alkali stress in agro-pastoral ecotones remain unclear. Methods: We characterized bacterial and fungal communities in four typical saline–alkali habitats in the agro-pastoral ecotone of the Loess Plateau [saline–alkali flat (SAF), natural grassland, maize cropland, and shrubland] via Illumina MiSeq sequencing. We analyzed community compositions, α-diversity, co-occurrence network characteristics, and functional group differences, using Mantel tests, redundancy analysis (RDA), and partial least squares path to examine environmental drivers of microbial structure and function. Results: Saline–alkali stress significantly altered soil physicochemical properties ( P < 0.05), with SAF exhibiting higher pH, EC, Na ⁺ , and low available nutrients. Bacteria α-diversity differed significantly among habitats ( P < 0.05), suggestive of sensitivity to saline–alkali stress. Under such stress, bacterial co-occurrence networks simplified with intensified interspecific competition, whereas fungal networks maintained high modularity (0.77–0.81) and were dominated by positive correlations (>93%), reflecting a synergistic coexistence. Functionally, saline–alkali stress inhibited bacterial chemoheterotrophy, aerobic ammonia oxidation, and nitrification. Saline–alkali stress also promoted fermentation, phototrophy, and nitrate reduction and jointly drove microbial functional expression, with pH, available phosphorus, and soil organic carbon (SOC) identified as key drivers ( P < 0.05). Conclusion: We identified adaptive strategies and functional differentiation of bacterial and fungal communities under saline–alkali stress. These findings provide important insights for the sustainable management and ecological restoration of saline–alkali lands in agro-pastoral ecotones.

Synergistic pollution–carbon mitigation is critical for China’s dual carbon targets. Taking coal-resource Shanxi Province as the case, this study developed an integrated Long-range Energy Alternatives Planning (LEAP)–Community Multiscale Air Quality (CMAQ) coupled framework combined with a three-dimensional vector model to simulate energy consumption, CO₂, and major air pollutant emissions (CO₂, CO, SO₂, NO₂, PM_2.5, and PM₁₀) under Baseline and Policy scenarios (2026–2050). The core novelty of this study lies in methodological innovation: the multi-model linkage realizes full-chain energy-emission-atmosphere simulation, remedying the isolation flaw of single models in prior research. The results indicated that low-carbon levels would rise steadily in both scenarios from 2026 to 2050. The Policy scenario achieved superior long-term low-carbon performance compared with the Baseline scenario and narrowed gaps in underdeveloped social subsystems, despite short-term transition costs. This scenario optimized the overall energy structure yet failed to fully reduce emission loads from residential and transport sectors. It drastically cut carbon and pollutant emissions, optimized spatial emission patterns, and decoupled most air pollutants from carbon emissions. However, this scenario still had prominent limitations: phased delays in emission abatement, strong coupling of CO, NO₂ and carbon emissions, and rising residential carbon emissions. Further pollution–carbon synergy assessment revealed worsening multi-dimensional imbalances under the Baseline scenario. While the Policy scenario experienced temporary systemic imbalance, its long-term coordination level improved steadily. This finding verified that systematic, long-term low-carbon governance constituted the core driver of Shanxi’s green transition. Targeted phased, classified collaborative governance strategies were proposed to resolve structural transformation risks for resource-based regions.