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Rapid and reliable methods for estimating the relative contribution of interrill and rill erosion during a rainfall event are needed to provide an improved understanding of soil erosion processes and to develop process-based soil erosion prediction models. Use of the radionuclide 7Be in controlled experiments provides a means of addressing this need and this paper reports an experimental study aimed at refining and testing procedures employed to estimate the relative contribution of the two components of erosion. Four experimental plots (area 5×2m and 10°, 15°, 20°, and 25° slope), filled with a loessial soil, manually tilled, and kept free of weeds with herbicides, were subjected to high intensity rainfall (91.8–120.6mmh−1), in order to induce rill development. The evolution of the rill network was documented photographically during the rainfall events and the runoff and sediment output from the plots were collected and measured. The sediment was recovered from the runoff and its mass and 7Be activity were measured. The Yang model, reported previously, was used to estimate the relative contributions of interrill and rill erosion from the 7Be activity of the exported sediment and this model was further refined to take account of the dynamic growth of the rills during the rainfall event. The results from the experiments were also used to develop a simple empirical linear model for estimating the relative contributions of interrill and rill erosion from the 7Be measurements. A comparison of the results provided by the three models showed some differences in the estimates of the magnitude of the relative contributions, although their trend during the event was similar. The estimates provided by the empirical linear model tended to be higher than those obtained using the refined model and lower than those generated by the Yang model, but were closer to those provided by the refined model which was seen as being theoretically the most accurate model. The basis of the empirical linear model was simpler than that of other models, since only a few, easily obtained parameters were required. In practical terms the empirical linear model therefore has important advantages and is judged to provide acceptable results. Further work is required to test its applicability under a wider range of conditions. [ABSTRACT FROM AUTHOR]

Abstract: An understanding of the spatial distribution of soil erosion and deposition in a catchment is important for designing soil and water conservation measures. Traditional monitoring techniques provide limited information on the spatial patterns of erosion and deposition. The fallout radionuclide 137Cs was used to document rates and patterns of soil redistribution within a small (0.17km2) gully catchment located near An''sai in Shaanxi Province, representative of the Loess Plateau of China. The local reference inventory was estimated to be 2266Bqm−2 and the 137Cs inventories of 198 soil cores collected from the catchment, ranged from 0 to 3849Bqm−2. The coefficient of variation of the inventories of the individual cores was 0.85, reflecting the complex pattern of 137Cs redistribution by soil erosion and deposition. Estimates of erosion rates derived from 137Cs measurement ranged from less than 25 to 150Mgha−1 year−1, with about 70% of the net soil loss from the catchment coming from the gully area. The 137Cs technique was shown to provide an effective means of documenting the spatial distribution of soil erosion and deposition within the small catchment. [Copyright &y& Elsevier]

Abstract: We systematically investigated the effect of post-deposition-annealing (PDA) on the electrical characteristics of Ge MOS capacitors with hafnium-oxynitride gate dielectric. The higher PDA temperature and longer PDA time was found to obtain the lower equivalent oxide thickness (EOT) of HfOxNy/Ge gate stack, however, with a larger hysteresis width. A lower EOT of 19.5 Å with a low leakage current of 1.8×10−5A/cm2 at VG =−1V was achieved after 600 °C annealing for 5 min. The improved capacitor properties after the PDA may be closely related to the different compositions and thicknesses of the resultant interfacial layers. [Copyright &y& Elsevier]

In this work, a series of new crystalline three-dimensional covalent organic frameworks (3D COFs) based on [8+4] construction was designed and successfully realized efficient photocatalytic acetylene (C2H2) hydrogenation to ethylene (C2H4). By regulating the hydrogen-localization transfer effect in these 3D COFs，the Cz-Co-COF-H containing cobalt glyoximate active centers exhibited excellent C2H2-to-C2H4 performance, with an average C2H4 yield of 1755.33 μmol g-1 h-1 in pure C2H2, also showed near 100% conversion of C2H2 in 1% C2H2 contained crude C2H4 mixtures (industry-relevant conditions), and finally obtain polymer grade C2H4. In contrast, the Cz-Co-COF-BF2 only showed one fifth activity due to lack of hydrogen-localization transfer. The density functional theory (DFT), projected density of states (PDOS) and molecular dynamics "slow-growth" kinetic calculations based on precise 3D COF structures confirmed that the rapid hydrogen species transfer, enhanced water dissociation and suitable C2H2 adsorption in COFs jointly contributed efficient photocatalytic acetylene hydrogenation (PAH). This work provides new opportunity towards rational design and development of crystalline photocatalysts for C2H2 hydrogenation., (© 2025 Wiley‐VCH GmbH.)

The connectivity (valency) of building blocks for constructing 3D covalent organic frameworks (COFs) has long been limited to 4, 6, 8, and 12. Developing a higher connectivity remains a great challenge in the field of COF structural design. Herein, this work reports a hierarchical expansion strategy for making 16-connected building blocks to construct 3D COFs with sqc topology. The [16 + 2] construction achieved by condensation between a 16-connected carbazolyl dicyanobenzene-based building block (CzTPN) and linear diamino linkers (BD or Bpy) affords two 3D COFs (named CzBD COF and CzBpy COF). Furthermore, attributed to the well-organized donor-acceptor (D-A) heterojunction, the Ni chelated CzBpy COF (Ni@CzBpy COF) exhibits excellent performance for photoredox/Ni dual catalytic C(sp 3 )-C(sp 2 ) cross-coupling of alkyltrifluoroborates with aryl halides, achieving a maximum 98% conversion and 94% yield for various substrates. This work developed the first case of high-connectivity COFs bearing 16-connected units, which is the highest connectivity reported until now, and achieved efficient photocatalysis applications, thus greatly enriching the possibilities of COFs.

The high local electron density and efficient charge carrier separation are two important factors to affect photocatalytic activity, especially for the CO 2 photoreduction reaction. However, the systematic studies on the structure-functional relationship regarding the above two factors based on precisely structure model are rarely reported. Herein, as a proof-of-concept, we developed a new strategy on the evaluation of local electron density by controlling the relative electron-deficient (ED) and electron-rich (ER) intensity of monomer at a molecular level based on three rational-designed vinylene-linked sp 2 carbon-covalent organic frameworks (COFs). As expected, the as-prepared vinylene-linked sp 2 carbon-conjugated metal-covalent organic framework (MCOFs) (VL-MCOF-1) with molecular junction exhibited excellent activities for CO 2 -to-HCOOH conversion (283.41 μmol g -1  h -1 ) and high selectivity of 97.1 %, much higher than the VL-MCOF-2 and g-C 34 N 6 -COF, which is due to the synergistic effect of the multi-electronic metal clusters (Cu 3 (PyCA) 3 ) (PyCA=pyrazolate-4-carboxaldehyde) as strong ER roles and cyanopyridine units as ED roles and active sites, as well as the boosted photo-induced charge separation efficiency of vinyl connection and increased light utilization ability. These results not only provide a strategy for regulating the electron-density distribution of photocatalysts at the molecular level but also offers profound insights for metal clusters-based COFs to effective CO 2 conversion., (© 2023 Wiley-VCH GmbH.)

In this work, we innovatively assembled two types of traditional photosensitizers, that is pyridine ruthenium/ferrum (Ru(bpy) 3 2+ /Fe(bpy) 3 2+ ) and porphyrin/metalloporphyrin complex (2HPor/ZnPor) by covalent linkage to get a series of dual photosensitizer-based three-dimensional metal-covalent organic frameworks (3D MCOFs), which behaved strong visible light-absorbing ability, efficient electron transfer and suitable band gap for highly efficient photocatalytic hydrogen (H 2 ) evolution. Rubpy-ZnPor COF achieved the highest H 2 yield (30 338 μmol g -1  h -1 ) with apparent quantum efficiency (AQE) of 9.68 %@420 nm, which showed one of the best performances among all reported COF based photocatalysts. Furthermore, the in situ produced H 2 was successfully tandem used in the alkyne hydrogenation with ≈99.9 % conversion efficiency. Theoretical calculations reveal that both the two photosensitizer units in MCOFs can be photoexcited and thus contribute optimal photocatalytic activity. This work develops a general strategy and shows the great potential of using multiple photosensitive materials in the field of photocatalysis., (© 2023 Wiley-VCH GmbH.)

More than 56000 check dams have been built in the Loess Plateau, which capture around 0.95 Pg of organic carbon and act as an important carbon sink. However, the decomposition mechanism of organic carbon in the sediment in these dams is still poorly understood, and thus it is difficult to quantify their role in terrestrial carbon cycling. In this study, the mineralization culture was used as a simulated environment for the natural sediment environment. With the observations in the simulated environment, the decomposition rates of sediment organic carbon (SOC) were compared under different conditions to investigate the factors influencing the decomposition rate of SOC. The results showed that the average SOC decomposition rate of sediment under anoxic and aerobic conditions was (6.47±4.06) and (56.66±17.78) mg C·kg -1 ·d -1 , respectively. The decomposition rate of SOC in dam sedi-ment under burial conditions was only 11.4% of that under the assumed aerobic condition, indicating that burial condition significantly reduced SOC decomposition. Under anoxic conditions, chemical compositions in the sediment had a greater effect on the decomposition rate of SOC than the microorga-nisms. In contrast, the effect of microorganisms on the decomposition rate of SOC was more significant under aerobic conditions. The physical properties of sediment had little effect on the decomposition rate of SOC under both anoxic and aerobic conditions. Under natural conditions, the siltation dam acted as a carbon sink. When the dam breaks, SOC stored in the sedimentary anoxic condition would be quickly exposed to the air, followed by a significant increase in the decomposition rate, and thus acting as a carbon source.

Understanding the relationship between soil erosion and the changes in landscape patterns is important for guiding the management and development of watersheds. The Nangou watershed in Ansai County, Shaanxi on the Loess Plateau, is an area with the implement of "Grain for Green", ecological agriculture, ecological tourism and the demonstration of science and technology for landscape management. We quantified the spatial and temporal variations of landscape pattern and soil erosion from 1981 to 2018 using the GIS and the universal soil loss equation (USLE). The relationship between the soil erosion modulus and nine landscape pattern indices in three categories was analyzed using the principal component analysis at both plot and landscape levels. The results showed that, among the five landscape types, the spatial and temporal changes of cultivated land and woodland dominated the evolution of landscape patterns, which affected the concentration and distribution degree of the whole watershed. Soil erosion in the Nangou watershed decreased annually, with erosion area, erosion modulus and soil erosion intensity decreasing by 29.7%, 61.2%, and 73.4% from 1981 to 2018, respectively. The variation of cultivated land and forest land areas determined the changes of soil erosion modulus of the whole watershed. The change trend of landscape pattern index was consistent with that of soil erosion. "Grain for Green" Project was the major dri-ving force for the changes in the landscape pattern and for the reduction of soil erosion. The characteristic development and management could weaken soil erosion intensity in parts of the study area. The rational configuration of landscape types could effectively control soil erosion in a watershed. The combination of rational configuration and characteristic management could help achieve the goals for sustainable and high quality development of the watershed.

In order to understand the spatial variation of heavy metals in Shaanxi section of Weihe River, the contents and sources of Cd, Co, Cu, Pb, Sb, As, Ni, Cr, Zn, Mn in sediments at 17 sampling sites in Shaanxi section of Weihe River and its tributaries were analyzed. The results showed that the average contents of Cd, Co, Cu, Pb, Sb, As, Ni, Cr, Zn, Mn were 0.10, 1.24, 11.73, 11.95, 24.90, 24.91, 29.31, 54.18, 72.74, 626.85 mg·kg -1 , respectively. Except for that of Cd being greater than 1, the coefficient of variation for each of other heavy metals was less than 0.5. The peak contents of Cd, Pb and Cr were found at the sampling site of Bahe River, of Co and Mn at Heihe River, of Cu and Zn at Qingjiang River, and of Sb, As and Ni at Shawang Ferry, Xianyang Railway Bridge and Linjia Village, respectively. According to the results of correlation analysis, principal component analysis and cluster analysis, the elements of Cd, Co, Cu, Pb, Ni, Cr, Zn and Mn mainly originated from industrial and domestic sources, but Sb and As mainly originated from agricultural and geochemical sources.

Soil erosion in the ecologically fragile zone is severely affected by the intensified coal mining activities in the Yushenfu Mining Region of the Loess Plateau. Soil erosion controlling projects such as the "Grain for Green" program are continuously implemented by the government, which has effectively mitigated or even controlled soil erosion. Coal mining results in new environmental problems, which has changed the erosion characteristics and sediment transport in watersheds. In this study, we identified the sediment source trapped behind the check dam using a composite fingerprinting approach and clarified the impact of "Grain for Green" program and coal mining on variation of the amount and sources of sediment during two decades, in a representative check-dam which controlled the watershed of Laoyeman. The two decades were divided into two stages, i.e. an earlier decade (1990-1999) and a later decade (2000-2010) with respect to the implement of the "Grain for Green" program in the flood couplets sequence established during the running of the dam. The annual average thickness of flood couplets during 2000-2010 decreased from (42.7±29.9) cm to (16.6±13.7) cm during 1990-1999, and the annual sediment deposition per unit area (square meter) at the sampling site reduced from 579.9 kg·m -2 to 245.8 kg·m -2 . The main source of sediment was gully wall (averaged 79.2%±10.1%) during the study period. However, compared with sediment sources during 1990-1999, the contribution of sediment from slope during 2000-2010, which was greatly affected by the "Grain for Green" program, showed an increasing trend (average annual contribution increased by 7.4%). According to the coaling mining and the variation of rainfall erosivity, our results indicated that under the combined effects of the "Grain for Green" program and decreases of rainfall erosivity, the intensity of sediment production in the watershed was substantially decreased. Coal mining had important impacts on sediment contribution from the slope, and obviously affected soil erosion controlling effects of the "Grain for Green" program. It is obvious that coal mining has increased the risk of erosion and sediment production on the slope, and that soil erosion control on the slope should focus on areas affected by coal mining.

To effectively utilize the vegetation on grain-for-green slopes in the wind-water erosion crisscross region, it is necessary to determine the reasonable vegetation utilization intensity. We set up runoff plots on slopes which were not cultivated and were closed for many years in the Liudaogou catchment, a typical catchment in wind-water erosion crisscross region of the Loess Plateau. With artificial simulated rainfall experiments, the characteristics of runoff and sediment yield on slopes (10°, 20° and 30°) under different utilization intensity of vegetation were studied to select the reasonable utilization intensity. The results showed that the runoff rate in the process of rainfall simulation could be divided into two periods: rapidly increasing in the initial period and slow increasing or quasi-steady state in the middle and late periods. The variation of erosion rate during the rainfall was dependent on the slope. The utilization intensity had a significant effect on the runoff yield, which increased with the increasing utilization intensities. The slope gradient had a significant effect on the sediment yield, with the variation of sediment yield with slope gradient being: 20°>30°>10°. Compared with the unused (natural) plots, the relative runoff and sediment increased with increasing utilization intensities. Predicted based on the rainfall data, annual soil erosion amount on the slope would be basically lower than the tolerance level of soil loss when the vegetation cover on the slope surface reached 25% in 15 years after abandoning reclamation. More attention should be paid to the restoration and management of vegetation on the slope of 20° in this area.