This study establishes a probabilistic risk assessment framework for polycyclic aromatic hydrocarbons (PAHs) in Chinese soils by integrating bioaccessibility data and regional concentration variability. This approach provides more realistic and scientifically robust health risk evaluations compared to traditional total concentration-based methods. Through systematic literature review of 697 general land use sites and 245 industrially contaminated sites, PAHs contamination patterns were characterized across different land use types and regions. General land use soils showed pronounced north-south gradient with northern regions exhibiting 2-4 times higher contamination than southern regions. Industrially contaminated sites demonstrated severe contamination primarily in northern and southeastern coastal regions, with typical coking, steel smelting, and petrochemical plants showing one order of magnitude higher risk levels than general land use soils. Persistent PAHs accumulation in soils under general land uses was identified despite the emission reduction efforts, whereas a gradual decline was shown for industrially contaminated sites following remediation over the past decade. In addition, significantly lower bioaccessibility with a median value less than 35% for carcinogenic PAHs than low-ring PAHs were identified, reducing estimated health risks by approximately 50%. Spatial risk distribution was visualized through ArcGIS-based kriging interpolation using 1000 Monte Carlo simulated samples per region. Probabilistic assessment demonstrated that carcinogenic risks in soils under general land uses remained below the regulatory risk threshold of 1 × 10-6, whereas soils under industrially contaminated sites posed substantially higher risks, nearly two orders of magnitude higher than those under general land uses particularly in North China with a mean risk level of 1.73 × 10-5 magnitude. BaP and DahA were identified as primary risk drivers, contributing 71-86% to the total carcinogenic risks. Global sensitivity analysis further identified soil PAH concentration and bioaccessibility as the primary drivers of risk uncertainty, with child exposure duration playing an additional critical role in general land use settings. These findings underscore the necessities for bioaccessibility-integrated, region-specific, and land use-differentiated management strategies.

Peroxymonosulfate (PMS) based advanced oxidation processes using nano iron-biochar composites exhibited great potential in groundwater remediation, however, reconciling the reactivity-stability tradeoff remained challenging. In this study, intrinsic N-doped biochar coated Fe0/Fe2C composites were successfully synthesized via a facial two-step hydrothermal-calcination method. The calcination temperatures played a crucial role in determining the structural evolution of Fe/N/C active sites in composites. The composite prepared at 1000 degrees C (Fe@NC1000) displayed both remarkable reactivity and stability in the activation of PMS for monochlorobenzene (MCB) removal. The Fe@NC1000/PMS system exhibited significant promise for remediating actual organic-contaminated groundwater, characterized by complex conditions, including the coexistence of diverse inorganic anions and humic acid, wide pH range, and porous aquifer medium. The sp2-hybridized carbon, doped graphitic N and surface C-OH/C--O in the outer carbon shell and subsequently exposed Fe0/Fe2C inner core as the pivotal active sites in Fe@NC1000 synergistically contributed to PMS activation via the multiinterfacial reactions with high electron utilization efficiency. Consequently, MCB degradation in the Fe@NC1000/PMS system was primarily governed by radical pathways involving SO4 center dot- and & sdot;OH, contributing to 65.84% of MCB removal, while nonradical pathways played a minor role through 1O2 and surface electron transfer. These findings presented profound insights into the regulation of multi-interfacial structures in ironcarbon remedial materials to address the activity-stability tradeoff and the associated mechanisms involved in activating PMS for highly efficient and long-term remediation of organic contaminants in groundwater.

Effectively inhibiting metal leaching of cobalt-based nanomaterial remains a great challenge for its green and highly-efficient application in groundwater remediation utilizing advanced oxidation process. Thus, biochar encapsulated nanoscale CoFe2O4 composites were successfully synthesized for activating peroxymonosulfate (PMS) to degrade a recalcitrant monochlorobenzene (MCB). It is identified that the calcination temperature exhibited significant impacts on the structural transformation and encapsulated configuration of CoFe2O4 and carbon sheets in the composites. Compared with CoFe2O4 alone, the composite synthesized under calcination temperature of 600 °C (FeCo@C600) was endowed with the highest utilization efficiency of PMS (i.e., reaction stoichiometric efficiency (RSE) of 13.11% for FeCo@C600 vs 8.74% for CoFe2O4) and the lowest cobalt leaching rate (i.e., 0.24% for FeCo@C600 vs 21.56% for CoFe2O4). Consequently, excellent reusability, strong anti-interference to commonly co-existed anions and organic matter, and high effectiveness with low cobalt leaching level were exhibited in FeCo@C600/PMS system under the porous flow-through condition, underscoring its promising potential for practical groundwater remediation. Redox reaction of the encapsulated CoFe2O4 predominated the heterogeneous activation of PMS by FeCo@C600 which was facilitated by graphitic sp2-carbon within the carbon sheets and surface functional group (CO). Finally, an active reaction system composed of SO4−/OH-based radical pathway and 1O2-based nonradical pathway was formed, in which SO4− dominated the degradation of MCB. This study offered a facile strategy for constructing bimetallic-biochar nanomaterials with minimal metal leaching and mechanistic insights into activating PMS for green and efficient remediation of organic contaminated groundwater.

The co-occurrence of arsenic (As) and microplastics (MPs) in aquatic environments poses an emerging environmental challenge, particularly in mining-impacted regions. However, their interactions at iron mineral interfaces and the resulting environmental consequences remain poorly understood. This study systematically investigated how As(V) and MPs with different surface charges regulate ferrihydrite transformation and pollutant immobilization. By integrating adsorption kinetics and phase-transformation experiments with synchrotron XRDRietveld refinement, two-dimensional correlation spectroscopy (2D-COS), and high-resolution TEM-EDS linescanning, the surface charges of MPs were identified as an important factor controlling ferrihydrite transformation. Positively charged MPs (MPs(+)) were found to promote solid-state conversion to hematite (up to 39.4%), whereas negatively charged MPs (MPs(-)) favored solution-mediated transformation to goethite (56.3%). Notably, in the As(V)-MPs(-) system, MPs(-) partially alleviated the inhibition by As(V), nearly doubling the transformation rate and increasing hematite content to 34% compared to the As-only system. This shift facilitated the evolution of As from surface adsorption to a more stable association with the crystalline iron oxides. These findings suggest that MPs can act as active regulators, modulating ferrihydrite transformation and thereby influencing the long-term fate of co-existing contaminants. This work reveals a charge-dependent regulatory mechanism of MPs on ferrihydrite transformation and As immobilization, providing insights for assessing the fate of co-pollutants in iron-rich aquatic environments.

Mixed-species litter modifies decomposition rates through complex interplays driven by species composition and functional traits of litter. However, there remains no consensus on how ecosystem type, climate, species traits, and decomposition stage jointly influence the direction and magnitude of litter mixing effects. We conducted a global meta-analysis of 1,258 effect sizes from 91 field studies (1989–2024) to assess how ecosystem type, climate, and species traits influence mixed-species litter decomposition rates across different stages of decomposition. Decomposition rates of mixed-species litter were 4.4 % significantly higher than those of the mono-species litter. Synergistic effects were most pronounced in temperate and forest ecosystems. These effects were generally observed after 180 days, and peaked between 360 and 720 days, but they declined as decomposition progressed, often shifting to additive or antagonistic effects as recalcitrant compounds accumulated. The relationship between species diversity and mixing effects was not linear, depending on specific species combinations and proportions. Phylogenetic distance and litter quality divergence between species significantly affect the mixing effect of decomposition. The mixing effects of litter decomposition are highly context-dependent and temporally dynamic. Our results provide empirical support for a dynamic, stage-dependent theory of litter mixing effects, emphasizing that their strength and direction hinge on critical decomposition phases and trait-mediated interactions. Recognizing these temporal dynamics is essential for predicting biodiversity impacts on ecosystem carbon and nutrient cycling.

Antibiotic contamination has been a global agricultural issue due to heavy discharge and undesirable consequences. However, the link between antibiotic pressures and soil multifunctionality in agricultural ecosystems remains unclear. In this study, we investigated the antibiotic levels, soil functions, and their relationships in two land use types (peanut fields vs. maize fields) in a manure-amended agricultural area. The results showed a significant non-linear relationship between antibiotic pressures and soil multifunctionality in agricultural ecosystems. Antibiotics exhibited an inhibitory effect on soil functioning at high concentrations. Specifically, soil bacterial diversity and richness, earthworm abundance, and nitrogen mineralization were significantly suppressed by increasing antibiotic pressures. Increasing antibiotic contamination had peak effects on soil multi- functionality loss at a threshold of 81 %, resulting in a decrease of-1.24 in functions. Land use played a significant role in modulating the effects of antibiotic levels on soil multifunctionality. A significant response of soil function to antibiotics was observed only in peanut fields, not in maize fields. Additionally, differences in antibiotic pressures promoted the functional turnover in agricultural ecosystems. Therefore, controlling antibiotic contamination in soil is crucial for the sustainable provision of soil ecosystem functions, considering the role of land-use modulation in planning and management decisions.

Pharmaceutically active compounds have garnered increased attention as emerging contaminants due to their widespread presence and potential ecological impacts. This study conducted a field evaluation under varied rainfall conditions, assessing the effects of rainfall intensity and duration on pharmaceutical concentrations. Grab sampling was complemented by the deployment of diffusive gradients in thin films (DGT) passive samplers along two urban rivers in Beijing, China. Twenty-four target pharmaceuticals were detected, with concentrations ranging from 370 to 686 ng/L in the Beixiao River and 376 to 610 ng/L in the Qing River. Rainfall influenced pharmaceutical concentrations through either dilution or enhancement, depending on local factors. Rainfall had a minimal impact on DGT performance, while biofouling showed compound-specific effects. For about 70 % of the pharmaceuticals, hydrophilic poly tetrafluoroethylene (PTFE) membranes used over 9-15 days effectively minimized biofouling influence (M-biofouled/M-clean > 0.8). The effectiveness of DGT for long-term monitoring depended on the biofilm formation time. Overall, DGT proved to be a reliable tool for accurately characterizing pharmaceutical concentrations in dynamic water systems. This study represents the first attempt to evaluate DGT performance for pharmaceuticals under fluctuating concentration scenarios in the field, providing valuable insights into the occurrence and environmental behavior of these contaminants.

Pharmaceuticals have been widely detected in urban surface waters globally. However, few studies have used diffusive gradients in thin-films (DGT) passive sampling techniques to investigate the occurrence of pharmaceuticals in natural waters. In this study, a self-developed DGT sampler was used to determine concentrations of 35 pharmaceuticals in 42 surface water sampling sites from the North Canal Basin, an urban catchment in Beijing, China. A total of 26 pharmaceuticals were detected with total concentrations ranging from 85.2 to 8800 ng/L, and ritonavir was the dominant pharmaceutical with the highest mean concentration of 46.2 ng/L. The spatial distribution indicated that the wastewater treatment plants were the major source of pharmaceuticals in the study area. Besides, pharmaceutical concentrations gradually increased from upstream to downstream along the mainstream, which could be attributed to the transfer of pharmaceuticals with the water flow. The result of the multilevel ecological risk assessment showed that ritonavir and diclofenac posed the most significant ecological risk (medium risk) to aquatic organisms, which means that high concern and priority control are required. This study was the first attempt to apply the DGT to the North Canal Basin in Beijing, enriching the data on pharmaceutical contamination and providing a scientific basis for environmental managers.

The soil carbon cycling in terrestrial ecosystems on the Loess Plateau of China is particularly sensitive to the altered drying and rewetting (DRW) events exacerbated by prolonged drought due to global climate change. However, how microbes mediate carbon release under increased drought durations in the DRW treatment remains unclear. An indoor experiment was conducted by adjusting the length of dry period in soil samples from the Loess Plateau, including 5-day drying at 5

Presence of microplastics in soil environment has become an urgent issue for soil ecosystem health and soil functional maintenance.Identifying the occurrence and spatial variability of microplastics in soil is critical to reduce soil microplastics pollution at watershed scale.This study investigated the abundance,spatial variability,and related influencing factors of soil microplastics based on field investigation and lab work in a typical agricultural watershed in southwest China.Results shown that:(1)The average abundance of soil microplastics was 1087.5 n/kg,and the occurrence and abundance of soil microplastics was significantly affected by land use type.Higher microplastics abun-dance was usually found in facility agricultural land with the highest abundance of 1575 n/kg.Limited or no microplastics were found in forestland and garden soils,with forestland recording the lowest abundance at 580 n/kg.(2)Microplastics smaller than 1 mm predominated in agricultural soil,and main types of soil microplastics were fragments and films,and the most common observed colors were white,black,and transparent.The spatial var-iability of soil microplastics in abundance,compositions,shapes,sizes,and colors was determined by the land use pat-tern at watershed scale.(3)Anthropogenic activities and soil texture were important factors affecting the occurrence and abundance of soil microplastics.The presence of microplastics in soil tends to increase as the distance from villages and roads decreases,and this abundance is positively associated with silty particles content and negatively associated with sandy particles.Results of this study provide spatial distribution characteristics of soil microplastics,providing scientific guidance for sustaining soil health in agricultural watershed.

Understanding how carbon assimilation rates respond to water availability is crucial for diagnosing global carbon and water cycles. This study aims to investigate characteristics and drivers of gross primary productivity (GPP) responses to soil water availability using three parameters from a light-use-efficiency (LUE) model: WI, kW and alpha W, representing the inflection point, slope and lag effect of GPP response to soil water availability changes, respectively. We followed a hybrid modeling approach coupling an artificial neural network with the LUE model to derive model parameters and examine intricate relationships between these parameters and features characterizing climate, vegetation, nutrient deposition, soil properties and elevation across 196 eddy covariance sites. Relationships between the LUE model parameters and observed ecosystem properties were analyzed using partial dependence plots and Shapley additive explanation dependence plots. Our results revealed significant statistical differences in parameters across plant functional types. Specifically, forests exhibited lower inflection points, responding more steeply and immediately to water availability changes, contrasting with smoother and lagged responses from open shrubs. Vegetation seasonality, represented by variability of enhanced vegetation index (EVI) and seasonal EVI, was the most influential noncategorical factor, followed by soil properties. Notably, the relationships were predominantly nonlinear. Additionally, older forest ecosystems generally showed lower vulnerability while responding more steeply to relative soil water availability changes than younger forests. While aridity was less influential on parameter variability than anticipated, aridity seasonality was a primary driver for the inflection point. High temperatures and substantial diurnal and annual temperature ranges were linked to pronounced lag effects. Despite these findings, challenges remain regarding model accuracy on annual scales, parameter uncertainties and interactions between features. Overall, this study underscores the spatial heterogeneity of GPP responses to soil water availability and highlights the importance of considering variability in model parameters and GPP sensitivities across space and time.

Cropland transfer as one of the mainstream measures has been implemented for over two decades in China to enhance land productivity and resource use efficiency. Despite the widely demonstrated benefits of cropland transfer on household income, the role of education in improving household income through cropland transfer remains unclear. This study investigates the impacts of cropland transfer on household income and further explores the moderating effects of education on these effects by using panel data from the China Family Panel Studies (CFPS) with a two-way fixed effect model. We show that cropland transfer has increased rural household income. Cropland transfer-in increases both on-farm and off-farm income for households, while cropland transfer-out reduces on-farm income and increases off-farm income for households. Education moderates the effects of cropland transfer on rural household income. In the case of cropland transfer-in, education positively moderates the impact on household income, particularly enhancing on-farm income. In comparison, households with better-education demonstrate a negative contribution to increasing off-farm and total income through cropland transfer-out. The moderating effects of education on the contribution of cropland transfer to improve household income has a tipping point. This study offers decision makers valuable insights for improving household income and facilitating rural revitalization in China.

Tetracycline (TC), a widely used antibiotics, poses environmental risks due to its persistence and bioaccumulation potential. Visible light photocatalysis has emerged as a promising technique for TC degradation. In this study, a supramolecular self-assembled TiO2/g-C3N4 (S-TCN) heterojunction and a weakly mixed TiO2/g- C3N4 (W-TCN) were synthesized via a one-pot method to elucidate the impact of interfacial coupling strength on photocatalytic performance. The results demonstrated that S-TCN, with robust Ti-O-C and N-O-Ti bonds, exhibited enhanced interfacial coupling, reduced interfacial resistance, and increased photocurrent density, improving electron transfer and carrier separation. Under simulated visible light, S-TCN achieved superior TC degradation efficiency (85.0 % within 60 min), outperforming W-TCN and previously reported photocatalysts. Radical scavenging and EPR analyses confirmed center dot O2- as the primary active species, with additional contributions from h+, e-, center dot OH, validating the Z-scheme charge transfer mechanism. UPLC/Q-TOF MS analysis revealed four major TC degradation pathways, including hydroxylation, demethylation, and ring-opening reactions, ultimately mineralizing. Environmental factor assessments demonstrated S-TCN's stable performance across various conditions. This study highlights the critical role of interfacial coupling in photocatalysis and underscores the potential of supramolecular self-assembly in designing advanced photocatalysts for wastewater treatment, providing valuable theoretical and practical insights.

To enhance the electron utilization capability and efficiency of iron-based materials in heterogeneous Fenton reaction of Fe3S4, WS2 was employed in this study to utilize interface electron transfer process to promote the Fenton oxidation for benzene, a typical contaminant in groundwater at industrially contaminated sites. The benzene removal rate in the WS2/Fe3S4/H2O2 system reached 79.79 % after a 120-minute reaction under the following experimental conditions: 0.15 g/L Fe3S4, 0.4 g/L WS2, 2 mmol/L H2O2, 20 mg/L benzene, and an initial pH of 7.0. Based on the systematic investigations using the XRD, SEM, EPR, XPS, electrochemical test and DFT calculation, it was observed that the incorporation of WS2 expedited the reductive regeneration of dissolved Fe2 + from Fe3S4 by donating sufficient electrons, achieving the enhanced generation of free center dot OH. Furthermore, a mechanism involving an electron donor-shuttle was identified, with W and S atoms serving as the electron donor and shuttle, respectively. The presence of S atoms in Fe3S4 significantly accelerated the electron transfer between W and Fe atoms, thereby promoting the regeneration of surface-bounded Fe2+ and the production of abundant surface-bounded center dot OH. The proposed WS2/Fe3S4/H2O2 system provided a feasible strategy for enhancing electron regeneration and utilization during remediation of organic contaminants in groundwater by iron-based Fenton- like systems.

The synergistic control of cadmium (Cd) and arsenic (As) co-contamination in paddy soils under fluctuating redox conditions remains a critical challenge for environmental remediation. This study developed magnesium-iron layered double hydroxides (Mg-Fe LDHs) from field-collected acid mine drainage (AMD) and elucidated their chemo-microbial coupling mechanisms in synchronously immobilizing Cd and As under alternating wet-dry conditions. During flooding, partial structural collapse of LDHs initiated their transformation into jarosite and subsequent drainage enabled LDH recrystallization, effectively preventing arsenic remobilization observed in conventional iron oxides under reductive conditions. Approximately 80-92 % reductions in concentrations of rice grain Cd, total As, and inorganic As (iAs) were achieved by applying 2 % LDHs without compromising rice yields. Mechanistically, sulfate-reducing bacteria (Thermodesulfobacteriota: +98 % abundance) and metalresistant genera (Streptomyces: +108 %, Pseudonocardia: +39 %) were selectively enriched by LDHs, while Fe/ As-reducing genera such as Geobacter and Bacillus were suppressed 50-60 % reduction. Correspondingly, sulfur metabolism genes (dsrA, 3.3-fold upregulation) and Cd efflux genes (cadA/czcA, 4.3-17.3-fold induction) were activated, whereas Fe/As reduction genes (geoB: 5.3-fold down-regulation; arsC: 3.9-fold down-regulation) were inhibited. These findings were collectively supported by correlation analysis and KEGG functional enrichment. Arsenic speciation was governed by elevated expression of the As(III) oxidase gene aioA (10-fold). This study provides an adaptive and agriculturally viable strategy for mitigating heavy metals in contaminated paddy soils.

Landscape patterns and water age are considered to play similar roles in influencing water quality, as human-caused landscape fragmentation usually leads to complex hydrological pathways and older water ages. The young streamflow fraction (Fyw), which can significantly alter water age, is believed to disproportionately impact water quality. Landscape and Fyw thus may play different roles in streamwater quality, but this assumption has not been examined. Here we examined the roles of Fyw (estimated by the amplitudes of seasonal cycles of oxygen isotope ratios in precipitation (Ap) and streamwater (As)) and landscape pattern (reflected by common landscape metrics) in streamwater quality over 7 forest-dominated catchments in eastern China. Landscape metrics, indicating land use arrangement, were closely related to multiple water quality parameters, suggesting a close association between stream water quality (sinks) and land use (sources). The Fyw had a positive relationship with ammonia nitrogen (R2 = 0.51, P = 0.044) and a negative relationship with nitrate nitrogen (R2 = 0.62, P = 0.022). The Fyw, determined by the heterogeneous-independent As/Ap, offers the possibility of modeling nitrogen compounds across multiple spatial scales. Importantly, the water quality parameters that significantly correlated with Fyw did not correlate with the landscape metrics. Differences in correlations of landscape and Fyw to water quality parameters imply that landscape and Fyw differed in their roles in water quality parameters, as well as the consideration for different water quality management strategies for different contaminants.

To deeply elucidate the intrinsic nature that impact Fenton activity of iron sulfide-based catalysts, iron sulfides with different electronic configurations and crystal structures (FeS, FeS2, Fe3S4, Fe7S8) were applied to activate H2O2 for degrading benzene. The benzene removal reaction exhibited two-stage pattern, where FeS, FeS2 and Fe3S4 were classified as one type of material with Fe7S8 as another type. In the first stage, the unstable crystal structure of Fe3S4 promoted the enhanced iron dissolution and accelerated redox cycle of dissolved iron, thus achieving the highest benzene removal rate (53%). In the second stage, the higher work function of Fe7S8 strengthened electric field from sufficient Fe3+, which in turn promoted iron cycle on Fe7S8 surface. Additionally, the lower energy difference between S p-band and Fe d-band center facilitated the internal iron cycle on Fe7S8. Thus, Fe7S8/H2O2 system obtained the highest benzene removal rate (86.6 %) in the second stage. This work not only provided the deep understanding into intrinsic causes of iron sulfides catalytic performance, but also offered valuable guidance to develop iron cycle-optimized heterogeneous iron-based materials for remediating organic contaminated groundwater.

Perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) as the two most typical perfluorinated compounds, their effective and rapid removal are still facing enormous challenges. In this study, the adsorption performance and mechanism of PFOA and PFOS by ball milled micrometer zero valent magnesium (mZVMg) were revealed firstly through the adsorption kinetics and isothermal, ions coexisting competitive adsorption and extraction experiments. Rapid adsorption equilibrium within 0.5 h was observed in the mZVMg system, and the higher adsorption affinities at 1.9 and 6.5 L/mg for PFOA and PFOS respectively were approximately 4.4-110 times higher than those of the carbon materials, layered double hydroxide and magnetite reported in the literature. Correspondingly, high removal efficiencies for PFOS were observed even under a wide pH ranging from 3.0 to 11.0. In the meantime, negligible influences on the PFOS adsorption were identified from the coexisting PFOA, perfluorobutanoic acid (PFBA), perfluorobutanoic sulfonic acid (PFBS), anions of Cl-, NO3- and SO 4 2- . Reversely, the PFOA adsorption was adversely influenced by enhanced electrostatic repulsion under the increased pH and the presence of the abovementioned anions. Additionally, the original removal efficiency of 67.18 % for PFOA in the absence of any cations and anions was decreased to 7.98 %, 31.08 % and 39.65 % respectively in the presence of humic acid, HCO3- and CO 3 2- . Similarly, the removal efficiency of 94.41 % for PFOS was declined to 40.01 %, 70.04 % and 80.58 % respectively when humic acid, HCO3- and CO 3 2- were added to the solution. However, in the presence of respective Mg2+ and Ca2+, the original removal efficiencies were increased from 67.18 % to 75.78 % and 74.68 % for PFOA, and from 84.99 % to 93.23 % and 92.49 % for PFOS, likely due to the cation's bridge effect. Consequently, the hydrophobic adsorption and electrostatic interaction accounted for 71.3 % and 19.75 % for PFOA, while 86.26 % and 5.85 % for PFOS removal, respectively through the solvent extraction and long-term effective removal experiments. Overall, this study provided an alternative, promising and environmental-friendly mZVMg for rapid adsorption of PFOA and PFOS.

Previous studies on microbial respiration responses to soil moisture have primarily focused on the influence of current moisture conditions, largely overlooking the role of antecedent soil moisture and its effects on the soil carbon (C) pool. In this study, we investigated the effect patterns of antecedent moisture on bacterial 16S rRNA composition, microbial respiration and the soil extractable organic carbon (EOC) pool by examining soils subjected to rewetting, drying and maintenance at constant moisture conditions. Bacterial community composition depended on both antecedent and current soil moisture. Specifically, rewetting decreased the relative abundance of Actinobacteriota and increased that of Proteobacteria, Myxococcota, Acidobacteriota and Gemmatimonadota, while that of Actinobacteriota, Proteobacteria, Chloroflexi and Entotheonellaeota increased after drying. The drying and rewetting treatments significantly affected substrate availability, as rewetting from antecedent drought facilitated the enrichment of soil EOC and induced a pulse in the respiration rate compared to drying from antecedent wetting. Additionally, most of the rewetting treatments increased the relative abundances of aromatic compounds. Soil moisture contents finally at 80 % water holding capacity (WHC) were most suitable for microbial respiration. Except for extreme drying, drying and rewetting treatments reduced C loss as drying promoted the integration of organic matter into the EOC pool via the desorption of aromatic substances and/or the lysis of microbial cells, which stimulated microbial respiration. The mechanistic and quantitative insights into the effects of antecedent moisture conditions on the soil C dynamic provided by this study will help reduce uncertainty in predicting soil C using current models.

Pharmaceuticals are ubiquitous contaminants in estuarine environments; however, the key environmental drivers and mechanisms governing their spatial distribution in estuarine sediments remain inadequately quantified. To address this knowledge gap, this study systematically evaluated the factors influencing pharmaceutical distribution in the estuarine sediments of Ningbo, Eastern China. We examined the interactions among human activity indices, watershed characteristics, sediment physicochemical properties, and dissolved organic matter (DOM). The concentrations of 13 target pharmaceuticals ranged from not detected (n.d.) to 519.5 ng/g dw. Carbamazepine (CBZ), clarithromycin (CLA), anhydro-erythromycin (ERY-H2O), roxithromycin (ROX), and venlafaxine (VFX) were the most prevalent compounds, with detection frequencies exceeding 80 % of samples. Higher total pharmaceutical concentrations were found in agricultural and aquaculture areas. Variance partitioning analysis (VPA) revealed that the combined variables explained 41 % of the variance in total pharmaceutical concentrations. Partial least squares path modeling (PLS-PM) further indicated that human activity indices, watershed characteristics, and physicochemical properties exerted their influence indirectly through DOM, while sediment physicochemical properties also showed a direct influence (r = 0.30, p < 0.05). Collectively, these drivers explained over 48 % of the variance for specific pharmaceuticals such as VFX and CBZ. Interaction analysis highlighted that synergistic effects, particularly between DOM and watershed characteristics, significantly amplified impacts on pharmaceutical accumulation. Overall, these findings clarify the complex interplay of factors controlling pharmaceutical concentration in sediments and underscore the central role of DOM in mediating their environmental distribution.