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Marsh Migration Into Forests and Farms: Effects on Soil Biogeochemistry Along the Salinity Gradients 沼泽向森林和农场的迁移:沿盐度梯度对土壤生物地球化学的影响
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-29 DOI: 10.1029/2025JG009149
Sean Fettrow, Ashleigh Montgomery, Dannielle Pratt, Holly Michael, Matthew Kirwan, Angelia L. Seyfferth

Sea level rise (SLR) and increased storm intensity are causing landward expansion of intertidal zones in the low-lying Delmarva Peninsula, allowing marsh migration into forests and agricultural fields. Transitional zones along the marsh-upland transects are visible aboveground as ghost forests and crop die-off, respectively. While the aboveground impacts of marsh migration are clear, the effects on belowground biogeochemistry are understudied. To characterize the impacts of marsh migration on soil biogeochemistry, we collected soil cores from marsh-upland transects at 3 agricultural and 3 forested sites along the Delmarva Peninsula. Soil cores were analyzed for both porewater chemistry and solid-phase characterization. Marsh end members support sulfate reduction; transitional zones support iron reduction; and upland end members support aerobic metabolisms at the surface, with iron reduction occurring at depth. In addition, the quality and quantity of dissolved organic matter changed across the transects, indicating differences in carbon source and cycling dynamics. Furthermore, our results show that soil carbon concentration varies drastically from lowland marsh to uplands, with marshes having 4–50 times more soil carbon than their upland endmembers. We also observed site-specific differences, where at the site with the lowest slope, the migrating marsh layer was relatively thin and was underlain by low-carbon aerobic soil that was coarser-textured. These findings have important implications for better understanding the incremental and belowground effects of SLR on coastal forests and agricultural lands.

海平面上升(SLR)和风暴强度增加导致低洼的德尔马瓦半岛潮间带向陆地扩张,使沼泽迁移到森林和农田。沿着沼泽高地样带的过渡地带在地面上分别可以看到幽灵森林和作物枯死。虽然湿地迁移对地上的影响是明确的,但对地下生物地球化学的影响还没有得到充分的研究。为了描述沼泽迁移对土壤生物地球化学的影响,我们收集了Delmarva半岛3个农业和3个森林样地的沼泽高地样地的土壤岩心。对土壤岩心进行了孔隙水化学和固相表征。沼泽端成员支持硫酸盐还原;过渡带支持铁还原;上行端成员支持表面的有氧代谢,铁还原发生在深度。此外,各样带溶解有机质的质量和数量也发生了变化,表明碳源和循环动态存在差异。此外,我们的研究结果表明,土壤碳浓度在低地沼泽和高地之间变化很大,沼泽的土壤碳含量是高地的4-50倍。我们还观察到特定地点的差异,在坡度最低的地点,迁移沼泽层相对较薄,下面是低碳好氧土壤,质地较粗。这些发现对于更好地理解SLR对沿海森林和农业用地的增量效应和地下效应具有重要意义。
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引用次数: 0
Carbon Dynamics in Artificial Aquatic Ecosystems: Comparing Greenhouse Gases and DOM in Stormwater and Natural Ponds 人工水生生态系统的碳动态:比较雨水和天然池塘中的温室气体和DOM
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-29 DOI: 10.1029/2025JG009374
A. H. Goeckner, M. A. Holgerson, J. D’Andrilli, A. R. Smyth, A. J. Reisinger

Urban stormwater ponds (SWPs) are increasingly recognized as critical hotspots for carbon (C) and nitrogen (N) cycling, driven by high external inputs and elevated internal productivity. In developed watersheds, SWPs often replace natural aquatic ecosystems at equal or greater densities, but direct comparisons of the C and N dynamics between these engineered and natural ecosystems remain scarce. During distinct wet and dry seasons (Florida, USA), we compared the diffusive air-water flux and hypolimnetic saturation of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as well as the composition of dissolved organic matter (DOM) between SWPs (n = 15) and naturally occurring clear (n = 3) and dark colored (n = 3) ponds in undisturbed watersheds. SWPs had similar CO2 and lower CH4 fluxes compared with natural-dark ponds, and higher fluxes than natural-clear ponds. Both natural pond types (clear and dark) were more stratified than SWPs, resulting in a greater CH4 buildup in the natural ponds. N2O fluxes were negligible across all pond types, with dark ponds being N2O sinks. SWPs contained unique humic DOM not found in natural ponds, as well as microbially derived DOM that was similar to, and humic DOM that was identical to, that of natural ponds. Our study underscores that SWPs differ from natural ponds in greenhouse gas production and DOM composition, providing evidence that these rapidly emerging ecosystems alter C forms and greenhouse gas fluxes in developed landscapes.

城市雨水池(SWPs)越来越被认为是碳(C)和氮(N)循环的关键热点,受到高外部投入和高内部生产力的驱动。在发达的流域,SWPs通常以相同或更高的密度取代自然水生生态系统,但这些工程生态系统和自然生态系统之间的C和N动态的直接比较仍然很少。在不同的干湿季节(美国佛罗里达州),我们比较了未受干扰的流域中SWPs (n = 15)和自然形成的透明(n = 3)和深色(n = 3)池塘之间的扩散空气-水通量和二氧化碳(CO2)、甲烷(CH4)和氧化亚氮(N2O)的低通量饱和度,以及溶解有机质(DOM)的组成。swp的CO2通量与自然暗池相似,CH4通量较低,而比自然清池高。两种天然池塘类型(透明池和暗池)都比SWPs更分层,导致天然池塘中CH4积累更多。所有池塘类型的N2O通量都可以忽略不计,深色池塘是N2O汇。SWPs含有天然池塘中没有的独特腐殖质DOM,以及与天然池塘相似或相同的微生物来源DOM。我们的研究强调swp在温室气体产生和DOM组成方面与天然池塘不同,这为这些快速形成的生态系统改变了发达景观中的C形态和温室气体通量提供了证据。
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引用次数: 0
Carbon Cycle Succession Across a Permafrost Thaw Gradient in Northeastern Alberta as Revealed by δ13C in Dissolved Solids, Gases, and Particulates in Lakes 湖泊中溶解固体、气体和颗粒物δ13C的变化揭示了阿尔伯塔东北部多年冻土融化梯度上的碳循环演替
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-29 DOI: 10.1029/2025JG009260
J. J. Gibson, P. Eby, A. Jaggi

δ13C in particulate organic carbon (POC), dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), carbon dioxide (CO2(g)) and methane (CH4(g)), together with geochemical modeling, were applied to describe carbon cycle evolution in 40 boreal lakes situated across a permafrost thaw gradient in northeastern Alberta, Canada, where hydrological and geochemical trends had previously been established in a multi-decadal study. Progressive carbon cycle succession, characterized by enhanced allochthonous carbon loading, methanogenesis, methane oxidation, and alteration of in-lake DIC regulation, is found to progress in response to periodic water input increases associated with permafrost thaw, and has resulted in modification of the carbon cycle processes in post-thaw lakes. Hydrologic indicators, including water yield (WY), groundwater—surface water ratio (GW/SW), and tritium content appear to undergo evolution across the thaw gradient, and proceed consistently among softwater, circumneutral, and hardwater lakes, although site-specific differences in underlying organic versus inorganic carbon source balances are apparent. Progressive CO2 supersaturation and CH4 increases generally accompany permafrost thawing. Isotopic signatures suggest mainly acetoclastic methane production, found in previous studies to be common for newly-thawed peatlands, subsequently modified by methane oxidation in 50% of lakes. Alteration of hydrologic, geochemical and carbon cycling processes has important implications for understanding potential trajectories of climate-driven changes near the southern margin of the zone of discontinuous permafrost.

本文应用颗粒有机碳(POC)、溶解有机碳(DOC)、溶解无机碳(DIC)、二氧化碳(CO2(g))和甲烷(CH4(g))中的δ13C,结合地球化学模型,描述了加拿大阿尔伯塔省东北部40个北方湖泊的碳循环演变,这些湖泊的水文和地球化学趋势此前已通过多年代际研究建立起来。以异源碳负荷、甲烷生成、甲烷氧化和湖内DIC调节的增强为特征的渐进式碳循环演替,在多年冻土融化相关的周期性水输入增加的响应中不断发展,并导致解冻后湖泊碳循环过程的改变。水文指标,包括产水量(WY)、地下水-地表水比(GW/SW)和氚含量似乎经历了整个融化梯度的演变,并在软水、环中性和硬水湖泊之间保持一致,尽管潜在有机碳源与无机碳源平衡的具体地点差异很明显。CO2过饱和和CH4的增加通常伴随着永久冻土的融化。同位素特征表明主要是丙酮碎屑甲烷的产生,在先前的研究中发现,在新融化的泥炭地中很常见,随后在50%的湖泊中被甲烷氧化改变。水文、地球化学和碳循环过程的变化对了解断续多年冻土带南缘气候驱动变化的潜在轨迹具有重要意义。
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引用次数: 0
Near-Term Forecasts of Dissolved Organic Matter Exhibit Consistent Patterns of Accuracy Across Multiple Freshwater Reservoirs 在多个淡水储层中,溶解有机质的近期预测显示出一致的准确性模式
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-28 DOI: 10.1029/2025JG009064
Dexter W. Howard, Mary E. Lofton, R. Quinn Thomas, Austin D. Delany, Adrienne Breef-Pilz, Cayelan C. Carey

Dissolved organic matter (DOM) plays an important role in aquatic carbon cycling and is a valuable metric of ecosystem functioning and water quality in freshwater ecosystems. Despite its importance for biogeochemical cycling and water quality, no near-term iterative forecasts have previously been developed for freshwater DOM concentrations. To advance both our understanding of freshwater DOM dynamics and management, we developed 1–34 days-ahead forecasts of fluorescent DOM (fDOM) in three drinking water reservoirs. These temperate reservoirs are co-located in Virginia, USA and experience variable DOM dynamics (range: 5–27 QSU (quinine sulfate units)). We developed six different forecasting models to predict fDOM in each reservoir. Three models were time series models based on forecasted drivers (water temperature and meteorology) that were updated daily from high-frequency fDOM sensors. The other forecast models included a neural network machine learning model and two baseline reference models (day-of-year mean and persistence). Altogether, our forecasts were able to capture observed dynamics over a year in all three reservoirs, with one time series model outperforming the baseline models across the full 34-day forecast horizon. Aggregated across reservoirs and models over a year, forecast RMSE increased from 0.7 to 4.1 QSU over the 1–34 days-ahead forecast horizon. Forecast skill varied substantially across seasons, with greatest accuracy in the spring and winter compared to the summer and fall across reservoirs. These forecasts can help improve our understanding of the predictability of DOM and inform management in freshwater ecosystems as carbon dynamics become more variable due to global change.

溶解有机质(DOM)在水生碳循环中起着重要作用,是衡量淡水生态系统功能和水质的重要指标。尽管它对生物地球化学循环和水质很重要,但以前没有开发淡水DOM浓度的近期迭代预测。为了提高我们对淡水DOM动态和管理的理解,我们在三个饮用水水库中进行了1-34天的荧光DOM (fDOM)预测。这些温带储层位于美国弗吉尼亚州,DOM动态变化(范围:5-27 QSU(硫酸奎宁单位))。我们开发了六种不同的预测模型来预测每个储层的fDOM。三个模型是基于预测驱动因素(水温和气象)的时间序列模型,这些驱动因素每天从高频fDOM传感器更新。其他预测模型包括一个神经网络机器学习模型和两个基线参考模型(日均值和持续时间)。总的来说,我们的预测能够捕捉到所有三个油藏在一年中观察到的动态,其中一个时间序列模型在整个34天的预测范围内优于基线模型。在1-34天的预测范围内,将所有油藏和模型汇总在一起,预测RMSE从0.7增加到4.1 QSU。不同季节的预报技能差异很大,春季和冬季的预报准确率最高,而夏季和秋季的预报准确率最高。这些预测有助于提高我们对DOM可预测性的理解,并为淡水生态系统的管理提供信息,因为全球变化导致碳动态变得更加多变。
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引用次数: 0
High-Resolution Soil Total Phosphorus Mapping for the Conterminous USA Using Machine Learning 使用机器学习的高分辨率美国土壤全磷制图
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-27 DOI: 10.1029/2025JG009098
Ikechukwu S. Onwuka, Daniel R. Obenour, Natalie G. Nelson, Owen W. Duckworth

Accurate estimates of soil total phosphorus (TP) concentrations are essential for sustainable nutrient management, food security, and water quality protection. This study predicts and maps the spatial distribution of TP in the top 5 cm and C horizon of soils across the conterminous USA (CONUS) using data from the Geochemical and Mineralogical Data for Soils of the Conterminous United States. We compare the performances of random forest (RF) and inverse distance weighting (IDW) to model and generate soil TP predictions. The RF incorporates 19 predictor variables, including spatial coordinates, climate, soil properties, and topography, while IDW relies solely on coordinates and interpolates between soil TP observations. Models are evaluated using five-fold cross-validation. The RF models outperform the IDW models and explain 52% (RMSE = 0.22 log10 mg kg−1) and 56% (RMSE = 0.26 log10 mg kg−1) of the variance in soil TP for the top 5 cm and C horizon, respectively. As expected, both model types identify higher TP concentrations in the top 5 cm than in the C horizon, particularly in agricultural regions, reflecting anthropogenic influences. Furthermore, the RF-generated maps show more realistic spatial patterns that capture the heterogeneity of the CONUS and avoid the bullseye patterns often characteristic of IDW-generated maps. Additional insights from the RF models show that coordinates, soil texture, pH, and climate are top predictors of soil TP. Increased availability of variables, such as iron and aluminum, that can bind with phosphorus in soils, could improve RF model performance.

准确估计土壤全磷(TP)浓度对可持续养分管理、粮食安全和水质保护至关重要。本研究利用美国土壤地球化学和矿物学数据,预测并绘制了美国(CONUS)土壤表层5 cm和C层全磷的空间分布。我们比较了随机森林(RF)和逆距离加权(IDW)在模拟和生成土壤全磷预测方面的性能。RF包含19个预测变量,包括空间坐标、气候、土壤性质和地形,而IDW仅依赖于坐标和土壤TP观测之间的插值。模型评估使用五倍交叉验证。RF模型优于IDW模型,分别解释了52% (RMSE = 0.22 log10 mg kg - 1)和56% (RMSE = 0.26 log10 mg kg - 1)的土壤TP变异。正如预期的那样,两种模式类型都发现,表层5厘米的总磷浓度高于C层,特别是在农业区,这反映了人为影响。此外,rf生成的地图显示了更真实的空间格局,捕捉了CONUS的异质性,避免了idw生成的地图通常具有的靶心格局。来自RF模型的其他见解表明,坐标、土壤质地、pH和气候是土壤全磷的主要预测因子。增加可用的变量,如铁和铝,可以与土壤中的磷结合,可以改善射频模型的性能。
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引用次数: 0
Assessing the Climate Impacts of Large-Scale Global Adoption of Cover Crops and Agroforestry 评估全球大规模种植覆盖作物和农林业对气候的影响
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-26 DOI: 10.1029/2025JG009268
Xia Zhang, Bo Huang, Francesco Cherubini

Cover crops and agroforestry are gaining prominence as climate-smart agricultural practices, offering mitigation and adaptation benefits through enhanced carbon sequestration, improved soil health, and biodiversity conservation. However, the biogeophysical climate impacts from the changes they induce in the surface energy balance are insufficiently understood. This study uses a coupled atmosphere-land model and field-based observations to investigate the upper-bound climate impacts from large-scale global adoption of these practices. Replacing bare soil with cover crops in winter reduces near-surface air temperature by about −0.3 ± 0.11°C in snow-free regions, primarily due to increased latent heat flux. In snow-covered regions, temperature responses are more variable due to albedo changes. Leafier and taller non-leguminous crops induce stronger cooling than legumes under both snow-free and snow-covered conditions. Agroforestry induces year-round cooling in the tropics (up to −0.14 ± 0.05°C annually) and warming in most extratropical areas due to snow-albedo feedbacks. The biogeophysical warming outside the tropics can be offset by the cooling contributions from increased carbon sequestration in vegetation and soil, and in snow-free areas biogeophysical cooling reinforces these benefits. Climate effects remain similar even when cover crops or agroforestry are applied across twice the cropland area, highlighting nonlinear system responses and opportunities to optimize cooling benefits through selective deployment. These findings underscore the importance of accounting for both biogeophysical and biogeochemical processes when evaluating sustainable agricultural practices and their capacity to support a transition toward climate change resilient agricultural systems that align local adaptation needs with long-term global climate mitigation goal.

作为气候智慧型农业做法,覆盖作物和农林业日益受到重视,通过加强碳固存、改善土壤健康和保护生物多样性,提供缓解和适应效益。然而,它们引起的地表能量平衡变化对生物地球物理气候的影响还不够清楚。本研究使用一个耦合的大气-陆地模式和基于实地的观测来调查大规模采用这些做法对气候的上限影响。冬季用覆盖作物替代裸露土壤可使无雪地区近地表气温降低约- 0.3±0.11°C,主要原因是潜热通量增加。在积雪覆盖的地区,由于反照率的变化,温度响应的变化更大。在无雪和积雪条件下,叶高的非豆科作物比豆科作物产生更强的降温作用。农林业导致热带地区全年变冷(每年高达- 0.14±0.05°C),而由于雪反照率反馈,大多数温带地区变暖。热带地区以外的生物地球物理变暖可以被植被和土壤中碳固存增加的降温贡献所抵消,而在无雪地区,生物地球物理降温强化了这些益处。即使覆盖作物或农林业的面积是农田面积的两倍,气候效应仍然相似,突出了非线性系统响应和通过选择性部署优化冷却效益的机会。这些发现强调了在评估可持续农业做法及其支持向气候变化抗御型农业系统过渡的能力时兼顾生物地球物理和生物地球化学过程的重要性,这种农业系统能使地方适应需求与长期的全球减缓气候变化目标保持一致。
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引用次数: 0
Environmental Drivers of Xylogenesis in Taxodium Distichum (Bald Cypress) in the Southeastern United States 美国东南部白头柏树(Taxodium Distichum)木质素发生的环境驱动因素
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-26 DOI: 10.1029/2025JG009004
Zachary W. Foley, C. Nathan Jones, Kimberly Lackey, Grant L. Harley, Richard D. Thaxton, Matthew D. Therrell

Bald cypress (Taxodium distichum (L.) Rich.), a foundation species in the bottomland hardwood forests of the southeastern United States, is essential for maintaining ecosystem functions. This study assesses the impacts of environmental changes on bald cypress ring widths and xylogenesis by correlating growth patterns with climatic variables, using ring-width data from 1775 ${-}$2022 and cellular development data from the 2023 growing season. We collected biweekly cambium samples from five trees in western Alabama, analyzing the correlation between cell development and environmental factors such as air and water temperatures, precipitation, water levels, solar radiation, and day length. Results indicate that new cell growth is significantly influenced by day length (r2 = 0.84, p < ${< } $ 0.01) and maximum water temperature (r2 = 0.59, p < ${< } $ 0.01), with water temperature potentially playing a role in initiating the growing season, which typically starts in late May and ends by early September. Notably, an intense precipitation event in early July, delivering 7.34 cm of rain, coincided with a mid-season increase in cell production after trees started to decrease production following the summer solstice, underscoring the sensitivity of bald cypress to acute hydro-meteorological events. The cessation of growth corresponded with the drying of the site, indicating water availability as a possible factor for ending the growth phase. These findings underscore the complex interaction between bald cypress and its changing environment, providing insights into its adaptive strategies to climatic variability and highlighting the ecological importance of this species in forecasting and managing wetland resilience.

秃柏树(Taxodium distichum, L.)是美国东南部低地阔叶林的基础种,对维持生态系统功能至关重要。本研究利用1775 - ${-}$ 2022年的环宽数据和2023年生长季节的细胞发育数据,通过将生长模式与气候变量相关联,评估了环境变化对秃柏树环宽和木质学的影响。我们从阿拉巴马州西部的五棵树中收集了两周的形成层样本,分析了细胞发育与环境因素(如空气和水温、降水、水位、太阳辐射和白天长度)之间的相关性。结果表明,日长(r2 = 0.84, p < ${<} $ 0.01)和最高水温(r2 = 0.59, p < ${<} $ 0.01)对新细胞的生长有显著影响,水温可能对生长季节的启动起作用。通常从5月底开始,到9月初结束。值得注意的是,7月初的一次强降水事件带来了7.34厘米的降雨,与此同时,在夏至之后树木开始减产后,细胞产量在季中增加,这突显了秃柏树对急性水文气象事件的敏感性。生长的停止与该地点的干燥相对应,表明水分供应可能是生长阶段结束的一个因素。这些发现强调了秃柏与其不断变化的环境之间的复杂相互作用,为其对气候变化的适应策略提供了见解,并突出了该物种在预测和管理湿地恢复力方面的生态重要性。
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引用次数: 0
Under-Ice Ecological and Biogeochemical Dynamics at the Onset of Spring Thaw in Four Arsenic-Contaminated Subarctic Lakes 四个砷污染亚北极湖泊春融开始时的冰下生态和生物地球化学动力学
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-24 DOI: 10.1029/2025JG009231
Amanda J. Little, Michael J. Palmer, Marc Amyot, Jennifer B. Korosi

Interactions between aquatic organisms and contaminants in under-ice lake environments are poorly characterized relative to ice-free seasons. Here, we compared under-ice arsenic biogeochemical processes and plankton community composition in four subarctic lakes spanning an arsenic contamination gradient. We focused on a short (7–10 days) late winter transitional period where lakes began to thaw but were still ice-covered; a potentially significant but understudied period of rapid biological and chemical change. We observed decreases in conductivity over the late winter transitional period, due to snowmelt influx. We also observed decreases in ice thickness and increases in photosynthetically active radiation, dissolved oxygen, and water temperatures, which corresponded with a proliferation of under-ice phytoplankton. The two study lakes with the highest under-ice arsenic concentrations experienced a dilution in the surface waters following the influx of snowmelt, while meltwater was likely a source of arsenic enrichment to the study lake with the lowest under-ice arsenic concentration. The introduction of oxygen into surface waters also shifted the arsenic pool to a higher relative fraction of arsenate compared to arsenite for lakes experiencing under-ice anoxia. The organic arsenic pool increased at spring thaw onset in 2022, as would be expected based on the increase in biological activity, a result not replicated in 2023. Arsenite was a statistically significant driver of late winter variation in phytoplankton assemblages, but not for zooplankton or rotifers. Overall, this study generates new insights into under-ice arsenic cycling and ecotoxicity in subarctic lakes, which remain ice-covered for much of year.

相对于无冰季节,冰下湖环境中水生生物与污染物之间的相互作用特征较差。在这里,我们比较了四个亚北极湖泊冰下砷生物地球化学过程和浮游生物群落组成,跨越砷污染梯度。我们关注的是一个短暂的(7-10天)冬末过渡时期,湖泊开始解冻,但仍然被冰覆盖;一个潜在的重要时期,但尚未被充分研究的生物和化学的快速变化。我们观察到,由于融雪涌入,在冬末过渡时期,电导率下降。我们还观察到冰厚减少,光合有效辐射、溶解氧和水温增加,这与冰下浮游植物的增殖相对应。冰下砷浓度最高的两个研究湖泊在融雪涌入后,其地表水出现了稀释,而融水可能是冰下砷浓度最低的研究湖泊砷富集的来源。与经历冰下缺氧的湖泊相比,将氧气引入地表水也使砷池中砷酸盐的相对比例更高。有机砷库在2022年春季解冻开始时增加,这是基于生物活性增加的预期,这一结果在2023年没有重复。亚砷酸盐是浮游植物群落冬末变化的统计显著驱动因素,但对浮游动物或轮虫没有影响。总的来说,这项研究对亚北极湖泊的冰下砷循环和生态毒性产生了新的见解,这些湖泊常年被冰覆盖。
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引用次数: 0
Inclusion of Explicit Soil Freeze-Thaw Dynamics in an Arctic Ecosystem Model Constrains Winter Warming Driven Carbon Loss 在北极生态系统模型中包含明确的土壤冻融动力学约束冬季变暖驱动的碳损失
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-22 DOI: 10.1029/2025JG008877
Kathleen Savage, Susan M. Natali, Christina Minions, Edward Rastetter, Edward A. G. Schuur, Jennifer D. Watts, Seeta Sistla

Arctic permafrost soils store vast amounts of carbon (C)-rich organic matter that has accumulated due to low temperatures that suppress microbial decomposition. As Arctic warming intensifies, soil microbes become increasingly active, even while plant growth remains dormant. Seasonal decoupling between plant and microbial decomposer growth can accelerate carbon dioxide (CO2) release from soils, however, most Earth system models underestimate cold-season C emissions and do not accurately represent the freeze–thaw transitions that govern microbial access to substrates during these critical periods. These model–data mismatches often stem from empirical formulations, such as using a fixed Q10 functions to represent microbial respiration, an oversimplification of a complex interplay of temperature, moisture, and substrate diffusion. To address this, we incorporated explicit, temperature-dependent diffusional constraints on microbial activity, (the Dual Arrhenius Michaelis–Menten (DAMM) model), into the Stoichiometrically Coupled Acclimating Microbe–Plant–Soil (SCAMPS) model which uses the Q10 function to represent microbial respiration. We used this enhanced model (SCAMPS_DAMM) to simulate Arctic ecosystem responses to a 50-year winter warming scenario and compared outcomes to the original SCAMPS framework. While both models predicted overall soil C losses under warming, SCAMPS_DAMM produced more constrained increases in microbial respiration and plant productivity. These differences led to similar total ecosystem C declines but divergent patterns of C and N allocation between plant and soil pools. Thus, incorporating mechanistic constraints on microbial access to substrates through explicit representation of temperature and moisture controls altered model projections of Arctic biogeochemical responses to climate change.

北极永久冻土层储存了大量富含碳(C)的有机物,这些有机物是由于低温抑制微生物分解而积累起来的。随着北极变暖的加剧,土壤微生物变得越来越活跃,即使植物生长仍然处于休眠状态。植物和微生物分解者生长之间的季节性解耦可以加速土壤中二氧化碳的释放,然而,大多数地球系统模型低估了冷季碳排放,并且不能准确地代表在这些关键时期控制微生物进入基质的冻融过渡。这些模型数据不匹配通常源于经验公式,例如使用固定的Q10函数来表示微生物呼吸,这是对温度、湿度和底物扩散的复杂相互作用的过度简化。为了解决这个问题,我们将微生物活性的明确的、温度依赖的扩散约束(Dual Arrhenius Michaelis-Menten (DAMM)模型)纳入化学计量耦合适应微生物-植物-土壤(SCAMPS)模型,该模型使用Q10函数来表示微生物呼吸。我们使用该增强模型(SCAMPS_DAMM)模拟了北极生态系统对50年冬季变暖情景的响应,并将结果与原始SCAMPS框架进行了比较。虽然这两种模型都预测了变暖下的总体土壤C损失,但SCAMPS_DAMM产生的微生物呼吸和植物生产力的增加更受限制。这些差异导致了相似的生态系统总碳下降,但植物库和土壤库之间的C和N分配模式不同。因此,通过明确表示温度和湿度控制,结合微生物进入基质的机制限制,改变了北极生物地球化学对气候变化响应的模式预测。
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引用次数: 0
Sediment Properties and NosZI Community Drive Nitrous Oxide Emissions in the Continuously Flooded Area of a Typical Urban Lake 典型城市湖泊连续淹水区沉积物特性和NosZI群落驱动氧化亚氮排放
IF 3.5 3区 环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES Pub Date : 2026-01-22 DOI: 10.1029/2025JG009262
Mengting Ji, Runhan Yang, Rui Su, Rui Huang, Jin Zeng, Dayong Zhao

Urban lakeshore zones characterized by highly spatiotemporal heterogeneity serve as critical hotspots for N2O emissions. While nosZI communities contribute to nitrous oxide (N2O) sink potential, their regulatory mechanisms in the urban lakeshores remain unexplored. Here, we investigated the variations and driving patterns of N2O fluxes and nitrogen (N) removal rates in continuously flooded (CF), semi-flooded (SF), and non-flooded (NF) zones of Pipa Lake in China during both summer and winter. Results revealed that CF zones exhibited seasonal N2O sink–source shifts (−14.73 and 9.00 μg m−2 hr−1 for summer and winter, respectively) and higher potential denitrification rates (0.63−43.73 nmol N g−1 hr−1) compared to SF and NF zones. These shifts were likely driven by seasonal variations in nosZI community abundance and composition in CF zones, for example, significantly reduced nosZI gene abundance (P < 0.05), and remarkably enriched taxa Azospirizaceae (40.43%) in the winter. Additionally, sediment carbon and nitrogen substrates exerted stronger direct effects on N2O emissions than indirect effects mediated by nosZI communities, while moisture regulated N2O emissions by suppressing nosZI abundance and enhancing carbon substrates. Under projected urban expansion scenarios, the CF zone would be a potential hotspot for N2O emissions, thereby exacerbating climate change. Consequently, managing sediment carbon and nitrogen substrates to modulate nosZI communities would present a viable strategy for N2O mitigation in urban lakeshores.

具有高度时空异质性的城市湖岸带是N2O排放的关键热点。虽然nosZI社区有助于一氧化二氮(N2O)汇潜力,但它们在城市湖岸的调节机制仍未被探索。本文研究了中国琵琶湖连续淹水(CF)、半淹水(SF)和非淹水(NF)带夏季和冬季N2O通量和氮(N)去除率的变化及其驱动模式。结果表明,与SF区和NF区相比,CF区存在季节性N2O库源转移(夏季和冬季分别为- 14.73和9.00 μg m−2 hr−1)和更高的潜在反硝化速率(0.63 ~ 43.73 nmol N g−1 hr−1)。这些变化可能是由CF区nosZI群落丰度和组成的季节变化驱动的,如nosZI基因丰度显著降低(P < 0.05), azosprizaceae类群在冬季显著丰富(40.43%)。此外,沉积物碳氮基质对N2O排放的直接影响强于nosZI群落介导的间接影响,而水分通过抑制nosZI丰度和增强碳基质来调节N2O排放。在预测的城市扩张情景下,CF区将成为N2O排放的潜在热点,从而加剧气候变化。因此,管理沉积物碳和氮基质以调节nosZI群落将是缓解城市湖岸N2O的可行策略。
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引用次数: 0
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Journal of Geophysical Research: Biogeosciences
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