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Landscapes evolution have significantly altered the Earth's energy balance and biogeochemical cycles, thereby exacerbating climate change. This, in turn, affects surface characteristics and the provision of ecosystem services, especially carbon storage. While recent centuries have witnessed unprecedented landscape changes, limited long-term studies have offered insights into the comparison between present-day features and historical conditions. This study utilized historical reconstruction data and remote sensing imagery to assess landscape evolution and its consequences for carbon stocks over 300 years. Employing multiple regression and random forest models were selected to quantify the influence of key landscape metrics on carbon stocks in the Dongting Lake basin, allowing for a thorough analysis across different sub-basins and land types. The results revealed that intensified human disturbances led to increased landscape fragmentation (+82%), regularity (+56%), and diversity (+37%) within the basin. Moreover, carbon stocks decreased from 4.13 Gt to 3.66 Gt, representing an 11.4% loss, with soil carbon stock experiencing the most considerable reduction (0.24 Gt, 51%). These changes in carbon stock metrics corresponded to shifts in landscape patterns, both undergoing significant transitions at the turn of the 21st century. Meanwhile, fragmentation and regularity played a vital role in explaining carbon stock changes, as their increase contributes to greater carbon losses. Likewise, an increase in landscape diversity correlated with decreased carbon stocks, challenging the prevailing notion that enhanced diversity promotes carbon stocks. The influence of landscape patterns on carbon stocks varies notably across distinct land types. An increase in the dominance of farmland and built-up land led to decreased carbon stocks, while the opposite holds true for forestland. Similarly, a decrease in regularity for farmland, forestland, and built-up land benefits carbon storage, while grassland demonstrates the opposite trend. These findings offer insights for countries and regions in the early stages of development or approaching development, suggesting improvements in land use practices and strategies to address climate change. This involves offsetting land-based carbon emissions through changes in landscape spatial configuration.

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Lakes, as integral social-ecological systems, are hotspots for exploring climatic and anthropogenic impacts, with crucial pathways revealed by continuous sediment records. However, the response of multi-proxies in large shallow lakes to typical abrupt events and sustained drivers since the Anthropocene remains unclear. Here, we explored the driver-identification relationships between multi-proxy peaks and natural and anthropogenic events as well as the attribution of short-term perturbations and long-term pressures. To this end, sediment core records, socio-ecological data, and documented events from official records were integrated into a large shallow lake (Dongting Lake, China). Significant causal cascades and path effects (goodness-of-fit: 0.488; total effect: -1.10; p < .001) were observed among catchment environmental proxies, lake biogenic proxies, and mixed-source proxies. The peak-event identification rate (PEIR) and event-peak driving rate were proposed, and values of 28.57%-46.43% and 50%-81.25% were obtained, respectively. The incomplete accuracy of depicting event perturbations using sediment proxies was caused by various information filters both inside and outside the lake. PEIRs for compound events were 1.41 (±0.72) and 1.09 (±0.46) times greater than those for anthropogenic-dominated and natural-dominated events, respectively. Furthermore, socio-economic activity, hydrologic dynamics, land-use changes, and agriculture exerted significant and persistent pressures, cumulatively contributing 55.3%-80.9% to alterations in sediment proxies. Relatively synergistic or antagonistic trends in temporal contributions of these forces were observed after 2000, which were primarily attributed to the "Grain for Green" project and the Three Gorges Dam. This study represents one of the few investigations to distinguish the driver-response relationship of multiple proxies in large shallow lakes under typical event perturbations and long-term sustained pressures since the Anthropocene. The findings will help policymakers and managers address ecological perturbations triggered by climate change and human activities over long-term periods.

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Interconnected river-lake systems record sedimentary organic carbon (OCsed) dynamics and watershed environmental changes, providing valuable information for global carbon budgets and watershed management. However, owing to the evolving river-lake interactions under global change, monitoring OCsed is difficult, thereby impeding the understanding of OCsed transport and fate. This study provided new insights into the dynamical mechanisms of OCsed in a typical river-lake system consisting of Dongting Lake and its seven inlet/outlet rivers (the three inlets of the Yangtze River and four tributaries) over the last century using stable isotope tracing and quantified the influences of climate change and human activities on OCsed. Results indicated that exogenous OC dominated the OCsed in the lake (58.2 %-89.0 %) and was lower in the west than in the east due to the differences in the material inputs and depositional conditions within the lake. Temporally, the distribution patterns of OCsed sources mainly responded to human activities in the basin rather than to climate change. Before 2005, the Yangtze River contributed the most OCsed (53.5 %-74.6 %), attributed to the high-intensity land use changes (path coefficient (r∂): 0.48, p-value < 0.01) and agriculture-industry activities (r∂: 0.44, p-value < 0.001) in the Yangtze River basin that increased soil erosion. After 2005, a large amount of Yangtze River OC was intercepted by the Three Gorges Dam, altering the OC exchange in the river-lake system and shifting OCsed dominance to the four tributaries (52.2 %-63.8 %). These findings highlight the active response of OCsed to the river-lake interaction evolution and anthropogenic control, providing critical information for regulating watershed management behavior under global change.

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The presence of residual antibiotics in the environment is a prominent issue. Photodegradation behavior is an important way of antibiotics reduction, which is closely related to dissolved organic matter (DOM) in water. The review provides an overview of the latest advancements in the field. Classification, characterization of DOM, and the dominant mechanisms for antibiotic photodegradation were discussed. Furthermore, it summarized and compared the effects of DOM on different antibiotics photodegradation. Moreover, the review comprehensively considered the factors influencing the photodegradation of antibiotics in the aquatic environment, including the characteristics of light, temperature, dosage of DOM, concentration of antibiotics, solution pH, and the presence of coexisting ions. Finally, potential directions were proposed for the development of predictive models for the photodegradation of antibiotics. Based on the review of existing literature, this paper also considered several pathways for the future study of antibiotic photodegradation. This study allows for a better understanding of the DOM's environmental role and provides important new insights into the photochemical fate of antibiotics in the aquatic environment.

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Coal, a reliable and economical fuel, is expected to remain the primary energy source for power generation for the foreseeable future. However, conventional mining and utilization of coal has caused environmental degradation and infrastructure damage. An in situ coal conversion method has been proposed to mitigate environmental problems and reduce CO2 emissions resulting from coal extraction and utilization. This method involves the in situ conversion and utilization of coal, backfilling of waste rock, and CO2 mineralization to backfill the goaf. In this study, the impact of mining and conversion activities on the surrounding strata was evaluated to ascertain the effectiveness and advantages of the in situ coal conversion method. Transparent stope models were created using three-dimensional printing technology. The stress distribution and deformation characteristics of the surrounding strata were examined using photoelasticity and digital image correlation methods. The results were compared with those obtained using the traditional backfill mining method. The comparison revealed that the disturbance to the surrounding strata was 14.4 times less in the in situ conversion method than in the traditional backfill mining method. Additionally, the disturbance height at the roof and the disturbance depth at the floor were 4.2 and 2.1 times lower, respectively. The roof subsidence in the in situ conversion method was 1.97 times less than that in the traditional backfill mining method. These results confirm the advantages of minimizing the disturbance to surrounding rocks and controlling the subsidence of roof strata.

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Ultra-high-performance concrete (UHPC) is a cement-based material with excellent impact resistance. Compared with traditional concrete, it possesses ultra-high strength, ultra-high toughness, and ultra-high durability, making it an ideal material for designing structures with impact resistance. The research on the impact resistance performance of UHPC and its composite structures is of great significance for the structural design of protective engineering projects. However, currently, there is still insufficient research on the impact resistance performance of UHPC composite structures. To study the impact resistance performance, experiments were conducted on UHPC targets using high-speed projectiles. The results were compared with impact tests on granite targets. The results indicated that when subjected to projectile impact, the UHPC targets exhibited smaller surface craters compared with the granite targets, while the penetration depth was lower in the granite targets. Afterwards, the process of a projectile impacting the UHPC composite structure was numerically simulated using ANSYS 16.0/LS-DYNA finite element software. The numerical simulation results of penetration depth and crater diameter were in good agreement with the experimental results, which indicates the rationality of the numerical model. Based on this, further analysis was carried out on the influence of impact velocity, impact angle, and reinforcement ratio on the penetration depth of the composite structure. The results show that the larger the incident angle or the smaller the velocity of the projectile is, the easier it is to deflect the projectile. There is a linear relationship between penetration depth and reinforcement ratio; as the reinforcement ratio increases, the penetration depth decreases significantly. This research is of great significance in improving the safety and reliability of key projects and also contributes to the application and development of ultra-high-performance materials in the engineering field.

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BACKGROUND: Radiofrequency ablation (RFA) has been recently applied as an alternative treatment in the patients with pulmonary malignancies. The aim of our study was to assess the incidence of complications and survival rate of RFA for malignant lung nodules, and evaluate the efficacy and safety of RFA in the treatment of inoperable patients with pulmonary malignant nodules. METHODS: The clinical data of 50 patients with primary and metastatic lung malignant nodules treated with RFA from June 2015 and July 2017 in Hebei General Hospital were considered, and the characteristics and clinical data of these patients were analysed. Complications, progression-free survival and overall survival at 1, 2 and 5 years of these patients were evaluated. RESULTS: Following the procedure. There were no major complications and deaths during the operation. 26 (52%) patients presented mild-to-moderate chest pain that was easily controlled by analgesic drugs. 8 (16%) patients with pneumothorax, 4 (8%) haemoptysis, 6 (12%) pneumonia, 7 (14%) pleural effusion and 1 (2%) postoperative bronchopleural fistula. Needle-track implantation was observed in 2 (4%) patients. Median progression-free survival (PFS) was 24.6 months. The PFS at 1, 2, 5 years was 76%, 52% and 20%, respectively. Median overall survival (OS) was 35.5 months. The OS at 1, 2 and 5 years was 80%, 58% and 32%, respectively. CONCLUSION: RFA is a safe and effective alternative treatment for the inoperable patients with primary or metastatic pulmonary malignant nodules. The clinical impact and long-term results of RFA need to be further confirmed in a larger series of patients, and RFA should ideally be compared with surgery.

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To compare early diabetic retinopathy (DR) severity level and the abilities in detecting early DR lesions among conventional five-field, ultrawide-field (UWF) Optos, and UWF Clarus fundus imaging methods. This was a single-center, prospective, clinic-based, and comparative study. In total, 157 consecutive patients with diabetes mellitus were enrolled in this study. All patients underwent comprehensive ophthalmological examinations. Following mydriasis, each eye was examined with conventional five-field, UWF Optos, and UWF Clarus fundus imaging methods. The initial UWF images were overlaid with a template mask that obscured the retina, which created a five-field view from UWF images (covered UWF images). The covered UWF images were then graded, after which the template mask was removed, and the original UWF images were also evaluated. All images were graded using the International Clinical DR severity scale. DR grades were compared and analyzed by weighted kappa statistics among the three fundus imaging methods. In total, 157 consecutive patients with diabetes (302 eyes) were enrolled in this study. Weighted kappa statistics for agreement were 0.471 (five-field vs. covered Optos), 0.809 (five-field vs. covered Clarus), 0.396 (covered Optos vs. covered Clarus), 0.463 (five-field vs. Optos), 0.521 (five-field vs. Clarus 133°), 0.500 (five-field vs. Clarus 200°), 0.323 (Optos vs. Clarus 133°), and 0.349 (Optos vs. Clarus 200°). The area under curve of covered Clarus images was higher than that of conventional five-field images at three different thresholds. Compared with conventional five-field and Optos fundus imaging methods, Clarus fundus imaging methods exhibited excellent performance in assessing early DR severity. Thus, Clarus fundus imaging methods were superior for early detection of DR.

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The abandonment of rice terraces in hilly agroecosystems in recent decades has caused substantial changes in microbial characteristics and their impact on microbial necromass carbon (MNC) and soil organic carbon (SOC). Nevertheless, the regulatory mechanisms and impact pathways of MNC remain unclear. Here, soil samples were collected from 0 to 120 cm soil profiles in rice terraces, dry land (DL), and forest land (FL) for analysis. After converting rice terraces to DL and FL, MNC decreased significantly by 31.12% and 38.33%, while SOC decreased significantly by 51.26% and 29.87% respectively. These reductions are due to the loss of terrace management practices and associated functions. There were no significant changes in bacterial necromass carbon (BNC), whereas fungal necromass carbon (FNC) experienced a significant decrease. As a result, the decline in SOC may be primarily attributed to the reduction in FNC. BNC and FNC were regulated by bacterial life history strategies and fungal biomass, respectively. However, bacterial copiotrophs experienced a significant reduction after rice terrace abandonment. The regulation of BNC may be influenced by other factors, potentially offsetting the negative impact of abandonment. Dissolved organic carbon and bulk density were the primary control factors for bacterial community composition and fungal biomass, respectively. Additionally, the impact of soil layers on the alterations in MNC and SOC was more significant compared to the abandonment of rice terraces. These findings indicate that short-term abandonment of rice terraces results in a decrease in SOC, potentially compromising the ecological service function of the hilly agroecosystems. In the face of rapid population growth and global warming, it is crucial to minimize terrace abandonment and enhance utilization rates. This approach will effectively support sustainable terrace management and ecological services.

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A total of 9 tests were carried out with 30 mm and 78 mm caliber scaled projectiles penetrating into granite targets. The penetration depth, crater diameter, and mass loss rate were examined and discussed. The results indicate that the dimensionless penetration depth of large-caliber projectiles is 20% greater than small-caliber projectiles. Based on the description of static resistance Ra in the Forrestal semi-empirical formula, the size effect of dimensionless penetration depth can be attributed to the size effect of static resistance Ra, and it can be seen that the penetration static resistance of projectile A is 40% higher than that of projectile B. Numerical simulations of projectile penetration into granite targets were conducted using the finite element program ANSYS/LS-DYNA. In terms of penetration depth and crater damage, the numerical simulation results agree well with the test data. This suggests that the selection of parameters was reasonable. The influence of compressive strength, projectile striking velocity, mass, diameter, and caliber-radius-head (CRH) ratio on the static resistance Ra were studied by RHT model parameterization. Based on the numerical results from the parametric study, an empirical formula was derived to predict the static resistance Ra.

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PURPOSE: This study compared the efficiency of diabetic retinopathy (DR) diagnosis and differences in the relative visible retinal area among the Early Treatment Diabetic Retinopathy Study (ETDRS) seven-field, ultra-widefield (UWF)-Optos, and UWF-Clarus fundus imaging methods. METHODS: This was a prospective and clinic-based comparative study. All patients underwent three fundus examinations, and all images were graded using the ETDRS severity scale. We compared and analysed the agreement of DR severity and the relative visible retinal area among the three fundus examination methods, and the number and type of lesions outside the ETDRS seven-field (peripheral lesions) between the two UWF imaging methods. RESULTS: A total of 202 patients (386 eyes) were included. Weighted kappa for the agreement between ETDRS seven-field and blinded Optos images was 0.485; between ETDRS seven-field and blinded Clarus images, 0.924; and between blinded Optos and Clarus images, 0.461. Blinded Clarus showed excellent performance when a ETDRS scale was used for grading the images. The relative visible retinal area for ETDRS seven-field images was 195 ± 28 disc area (DA); single Optos images, 371 ± 69 DA; single Clarus images, 261 ± 65 DA; two-montage Clarus images, 462 ± 112 DA; and four-montage Clarus images, 598 ± 139 DA. The relative visible retinal area was statistically significant between any two of the imaging systems used. In total, 2015 and 4200 peripheral lesions were detected in single Optos and Clarus images, respectively (P < 0.001). These peripheral lesions on two UWF images suggested a more severe DR level in approximately 10% and 12% of eyes, respectively. CONCLUSION: UWF-Clarus fundus imaging offers a suitable assessment approach for DR severity; it could improve DR diagnosis and has the potential to replace ETDRS seven-field imaging after additional clinical trials.

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Sediment organic carbon (SeOC) sources with rich information can be used as a "historical archive" reflecting anthropogenic activities in the catchment, which is crucial to carbon management in the watershed. Anthropogenic activities and hydrodynamic conditions significantly influence the river environment and are reflected by the SeOC sources. However, the key drivers of the SeOC source dynamics are ambiguous, which restricts the behavior of regulating the carbon output of the basin. In this study, sediment cores from the lower reach of an inland river were selected to quantify the SeOC sources based on a centennial scale. A partial least squares path model was used to establish the relationship between anthropogenic activities and hydrological conditions with the SeOC sources. Findings showed that the exogenous advantage of SeOC composition was gradually significant (early period: 54.3%; middle period: 81%; later period: 82%) from the bottom layer to the surface layer of the sediments in the lower reach of the Xiangjiang River. Factors related to anthropogenic activities controlled the external input of SeOC (δ13C: r∂ = -0.94, P < 0.001; δ15N: r∂ = -0.66, P < 0.001). Different anthropogenic activities performed different effects. Land use change aggravated soil erosion and brought more terrestrial organic carbon to the downstream. The variation of grassland carbon input was the most obvious (from 33.6% to 18.4%). In contrast, the reservoir construction intercepted upstream sediments, which might have been the main reason for the slow growth of terrestrial organic carbon input in the downstream in the later period. This study provides a specific grafting for the SeOC records - source changes - anthropogenic activities in the lower reach of the river, which provides scientific basis for watershed carbon management.

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Sediment organic carbon (SOC) is a precious archive that synthesizes anthropogenic processes that remove geochemical fluxes from watersheds. However, the scarcity of inspection about the dynamic mechanisms of anthropogenic activities on SOC limits understanding into how key human factors drive carbon dynamics. Here, four typical basins with similar natural but significantly diverse human contexts (high-moderate-low disturbance: XJ-ZS and YJ-LS) were selected to reconstruct sedimentation rates (SR) and SOC dynamics nearly a century based on 200-cm corers. A partial least squares path model (PLS-PM) was used to establish successive (70 years) and multiple anthropogenic data (population, agriculture, land use, etc.) quantification methods for SOC. Intensified anthropogenic disturbances shifted all SR from pre-stable to post-1960s fluctuating increases (total coefficient: high: 0.63 < low: 0.47 < medium: 0.45). Although land use change was co-critical driver of SOC variations, their trend and extent differed under the dams and other disturbances (SOC mutated in high-moderate but stable in low). For high basin, land use changes increased (0.12) but dams reduced (-0.10) the downstream SOC. Furthermore, SOC mutation corresponded to soil erosion due to urbanization in both periods A and B. For moderate, SOC was reversed with the increase in afforestation and cropland (-0.19) due to the forest excitation effect and deep ploughing, which corresponded to the drought in phase B and the anthropogenic ecological project in A. For low, the increase in SOC corresponded to the Great Leap Forward deforestation in period B and the reed sweep in A, which suggested the minor land change substantially affected (0.16) SOC in fragile environments. Overall, SOC dynamics revealed that anthropogenic activities affected terrestrial and aquatic ecosystems for near the centenary, especially land use. This is constructive for agroforestry management and reservoir construction, consistent with expectations like upstream carbon sequestration and downstream carbon stabilization.

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A deeper understanding of the rainfall-flow processes can improve the knowledge of the rain-driven erosional processes in coarse-textured agricultural soil. In this study, on the red soil slope farmland developed from weathered granite, a simulated rainfall experiment was conducted to study the characteristics of rainfall redistribution, the processes of surface-subsurface flow generation and prediction, and sediment production. Rainfalls with three intensities of 45, 90, and 135 mm h-1 with a duration of 90 min were applied to the weathered granite red soil with the slope gradient of 10°. Under 45 mm h-1 rainfall intensity, the output of rainwater was composed by subsurface flow and bottom penetration, accounting for 35.80% and 39.01% of total rainfall, respectively. When the rainfall intensities increased to 90 and 135 mm h-1, the surface flow became the main output of rainwater, accounting for 83.94% and 92.42%, respectively. Coarsened soil exhibited strong infiltration-promoting but poor water-storage capacities under light rainfalls. With an increased rainfall intensity, the surface flow coefficient increased from 19.87% to 92.42%, while the amount of subsurface flow and bottom penetration decreased by 1.3 and 6.2 L, respectively. For sediment production, the sediment concentration was raised from 1.39 to 7.70 g L-1, and D10, D50, and D90 increased by 1.50, 1.83, and 1.40 times, respectively. The content of coarse particles (>1 mm) in surface soil increased by 12%, while the content of fine particles (<0.5 mm) decreased by 9.6%. Under strong rainfalls, severe soil and water loss, coarsening soil surface, and large loss of fine particles became major problems. During rainfall, the subsurface flow and bottom penetration could be predicted well through quadratic equations of rainfall time, which transformed into time-dependent exponential functions after rainfall. The results provide a theoretical basis and data reference for soil erosion prevention and water management in coarse-textured agricultural lands.

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In recent decades, terraces abandonment has been prevalent in the hilly areas of China. Soil fungi play an important role in clarifying soil ecosystematic feedback after ancient rice terraces abandonment, but how their community composition and function shift remains unclear. Soil profiles of 0-120 cm were excavated in ancient rice terraces, dry land, and forest land (formed from ancient rice terraces abandonment), respectively. The 13C NMR and high-throughput sequencing were used to determine soil organic carbon chemical groups and fungal community, respectively, and FUNGuild was used to predict functional groups. The results showed that the soil fungal community changed from Ascomycota to Basidiomycota after ancient rice terraces abandonment. The trophic modes of dry land and forest land were transformed into pathotrophic fungi and symbiotrophic fungi, respectively. The number of nodes and edges of fungal co-occurrence networks increased by 83.8% and 644.1% in dry land, and 81.3% and 431.2% in forest land, respectively. Moreover, soil nutrients (especially DOC, TN, and TP) can more affected the variation of fungal community composition and function than soil organic carbon chemical groups. These findings indicate that soil fungal community shifts in different directions in response to ancient rice terraces abandonment, which is related to the adaptive strategies for environmental changes and may be more conducive to the acquisition and turnover of soil nutrients.

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Microbial communities and functions play an important role in soil carbon and nitrogen transformations, and, in recent decades, the abandonment of terraces is prevalant in the hilly areas of China. However, it is unclear how soil carbon and nitrogen contents and prokaryotic communities changed as a result of the abandonment of ancient rice terraces. Soil profiles ranging from 0 to 120 cm were excavated on drylands, forestlands (both converted due to the abandonment of ancient rice terraces), and ancient rice terraces. The FAPROTAX database was used to predict soil prokaryotic functional groups. The results showed that soil organic carbon (SOC) and total nitrogen (TN) contents of abandoned ancient rice terraces in drylands (51.09 and 33.20%) and forestlands (31.76 and 16.59%) were significantly reduced. Soil prokaryotic diversity and community composition changed dramatically after the abandonment of terraces and were mainly affected by soil pH and ammoniacal nitrogen ( NH 4 + -N). Community composition was more similar in drylands and forestlands. Moreover, the abundance of transformation functional genes of carbon (57.01 and 50.80%) and nitrogen (15.25 and 22.36%) in bacterial communities was significantly reduced, and of carbon in the archaeal communities decreased sharply (28.10 and 46.50%), in drylands and forestlands. These findings indicate that short-term abandonment of ancient rice terraces reduces soil carbon and nitrogen contents, which may be closely related to the decline of prokaryotic functional groups. The prevalence of short-term abandonment of rice terraces in the hilly areas of China may pose adverse ecological risks.

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Total organic carbon (TOC) in lake sediments from upstream catchments is deposited and buried in substrate, recording historical environmental changes. However, the linkage among natural variability, anthropogenic activity, and TOC burial for has not yet been clarified. This study examined the lake sediments of five 200-cm-deep dated depositional cores in west Dongting lake, China to quantify the magnitude, allocation, and amplitude of TOC burial. 44.47-59.36% of TOC burial flux was buried at 100-200 cm, suggesting lake sediments at deep layers stored considerable carbon. TOC burial rate (BRTOC) decreased along the lake entrance to its body, which was explained by the geochemical differences. Since 1900, BRTOC presented an increasing with a 4-7 times uptrend, showing three sedimentary stages with the increased human disturbance, such as deforestation, hydroelectric facilities. Moreover, the coefficient of variation of BRTOC in the third stage was lower than that in the second stage for the implementation of watershed reforestation and reservoir construction. Our findings stressed that natural variations of lake sedimentation background induced the change of TOC burial among the depositional sites, and enhanced that anthropogenic perturbation drove its chronological increases. This research unveiled the linkage between TOC burial, natural variability, and human disturbance from the perspective of burial evolutions in a lacustrine sedimentary environment.

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The characteristics and sources of DOM in sediments are significantly affected by fluctuations in lake water levels. However, the impact of spatial differences on water levels remain unclear. Here, 36 sediment samples were collected from the flood passage and coastal beach of East Dongting Lake. The differences in the composition and source of DOM in sediments under perennial inundation and seasonal inundation were studied using UV-visible absorbance (UV-Vis) and fluorescent excitation-emission matrix (EEM)-parallel factor analysis (PARAFAC). Three fluorescent components of DOM in the sediment were identified. The relative abundance of protein-like components was as high as (72.95±8.94)%, including tryptophan (C2) and tyrosine (C3). However, the humic-like component (C1) abundance was (27.05±8.94)%. Compared with that in perennial inundation, DOM in seasonal inundation had a higher and lower relative abundance of protein-like components and humic-like components, respectively. Further, the aromatic and hydrophobic components were higher in perennial inundation, showing a spatial pattern of the middle>entrance>outlet of the lake, which was more conducive to the migration of pollutants. The high FI (1.93) and BIX (0.91) and low HIX (1.57) indicated that the DOM in sediments had the mixed characteristics of being mainly endogenic and relatively weakly terrigenous. This was mainly influenced by human input and sediment characteristics. The direct effect of sewage discharge was intensified by sediment exposure in the seasonal inundation zone. Additionally, the contents of clay and total nitrogen (TN) were significantly positively correlated with FI, indicating that high nutrients and clay in sediments enhanced the endogenous input of DOM (FI>1.9). The perennial inundation zone was influenced by external runoff input. At the same time, the pH and C/N were significantly positively correlated with HIX and C1, indicating that DOM in the sediments had higher terrigenic characteristics (HIX=1.38±0.57) than those in the seasonal inundation zone owing to the alkaline environment (pH>7.5) and runoff input. The results above revealed the relevant theories of the response of DOM in sediment to water quality and pollution in the process of hydrology and human activities and provide a scientific basis for the prevention and control of sediment pollution in lakes.

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Organic matter (OM) tracing is critical for understanding the processes of soil redistribution and global carbon cycling. It effectively supports ecological management and global climate change prediction. Stable isotopes are generally more source-specific compared with other tracers and identify OM sources with a higher level of accuracy. Nevertheless, stable isotopes may be enriched or depleted by physical and biochemical processes such as selective migration of particles and OM mineralization in transport and sedimentary environments, making it difficult to establish links between the source and sink regions. Literature on OM source identification tends to assume a direct link between stable isotope sources and sinks, ignoring the non-conservatism of stable isotopes. There is further literature on understanding and modeling the processes that link the sources to sinks in terms of the non-conservatism of stable isotopes. The disagreement in response to the non-conservatism lies in the lack of comprehensive understanding of stable isotope fingerprinting systems and non-conservatism. The development of stable isotope fingerprinting technology is full of challenges. This review outlines the applicability of stable isotope tracers, identification mechanisms, and associated quantitative models, intending to improve the stable isotope fingerprinting system. We highlight the non-conservatism of stable isotopes in space and time caused by physical and biochemical processes. Additionally, a decision tree is established to determine the quantitative tools, evaluation indicators, and procedures related to non-conservatism. This decision tree clarifies the process from non-conservatism detection to threshold determination of statistical quantification, which can guide the end-users to better apply stable isotope to trace OM sources.

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A clear quantification and spatial mapping between supply and demand of water provision service in relation to climate change and urban expansion can provide some guidance to water resources management. Nevertheless, so far, most researches ignored the dynamic changes and influences of supply-demand coupling correlations. In this study, water yield and water demand were quantified and mapped in the Xiangjiang River Basin (XRB) from 2000 to 2018 by using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) and water-demand models, then the spatial distribution characteristics and their matching relationship were identified by using the univariate local autocorrelation analysis and the common logarithm of water supply-demand ratio (WSDR). With that, the contributions of climate and socio-economic factors to the above-mentioned changes were explored by using geographic detector. Results showed that the annual water yield increased by 20.20% in 2000-2015 and decreased by 33.92% in 2015-2018 affected by precipitation and land use changes; Changsha-Zhuzhou- Xiangtan urban agglomeration (CZX) and Southwest of Yongzhou were the high value areas of water yield (>338 m3/hm2). Due to the urban expansion, the water demand increased by 40.50% from 2000 to 2005 and decreased by 36.39% after 2005; From 2000 to 2018, high value areas of water demand (>53566 m3/hm2) mainly appeared in midstream and downstream with high urbanization level, dense population and developed industry. Under the joint action of precipitation (prep) and urban expansion, the overall state of supply and demand in the upper reaches was surplus, and more than 90% of the regions in midstream and downstream were at the middle and high level of supply shortage, especially in Hengyang and Chenzhou. Consequently, the increasing needs of human beings should be emphasized from the overall perspective of the basin, the growth rate of construction land and the necessary green infrastructure should be controlled reasonably and configured for achieving win-win goals of coordinating environmental protection and urban development.

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