During the initial impoundment period of a canyon-shaped reservoir,the water body fluctuated violently regarding water level,hydrological condition,and thermal stratification.These variations may alter the structure o...During the initial impoundment period of a canyon-shaped reservoir,the water body fluctuated violently regarding water level,hydrological condition,and thermal stratification.These variations may alter the structure of phytoplankton community,resulting in algal blooms and seriously threatening the ecological security of the reservoir.It is of great significance to understand the continuous changes of phytoplankton in the initial impoundment period for the protection of reservoir water quality.Therefore,a two-year in-situ monitoring study was conducted on water quality and phytoplankton in a representative canyonshaped reservoir named Sanhekou and the interannual changes of phytoplankton community and its response to environmental changes during the initial impoundment period were discussed at taxonomic versus functional classification levels.The results showed that the total nitrogen and permanganate index levels were relatively high in the first year due to rapid water storage and heavy rainfall input,and the more stable hydrological conditions in the second year promoted the increase of algae density and the transformation of community,and the proportion of cyanobacteria increased significantly.The succession order of phytoplankton in the first year of the initial impoundment periodwas Chlorophyta-Bacillariophyta-Chlorophyta,or J/F/X1-P/MP/W1-A/X1/MP,respectively.And the succession order in the second year was Cyanobacteria/Chlorophyta-Bacillariophyta-Chlorophyta,or L_(M)/G/P-P/A/X1-X1/J/G.Water temperature,relativewater column stability,mixing depth,and pHwere crucial factors affecting phytoplankton community succession.This study revealed the interannual succession law and driving factors of phytoplankton in the initial impoundment period and provided an important reference for the operation management and ecological protection of canyon-shaped reservoirs.展开更多
Metal-organic framework(MOF) has been widely applied in photocatalysis, which is significant for addressing energy crises and environmental issues. Based on density functional theory calculations,the performances of C...Metal-organic framework(MOF) has been widely applied in photocatalysis, which is significant for addressing energy crises and environmental issues. Based on density functional theory calculations,the performances of Cu-BTC, a copper-based MOF, and its derivatives Cu TM-BTC via the substitution of transition metal(TM) elements at the Cu site for photocatalytic overall water splitting(POWS) have been studied. POWS of Cu-BTC suffers from the sluggish hydrogen evolution reaction due to the large overpotential of 2.02 V and limited solar utilization due to a wide HOMO-LUMO gap of 4.11 e V. Via TM substitution, the HOMO-LUMO gap narrows but still satisfies the redox potentials when taken 3d-TM of Cr, Fe, Co or Ni, 4d-TM of Rh or Pd, or 5d-TM of Re or Pt into consideration, benefiting for the light absorption. Furthermore, Cr and Re could serve as active sites for hydrogen evolution with remarkably lowered overpotentials of 0.79 V and 0.28 V, respectively;similarly, oxygen evolution activities could be enhanced by Fe, Co and Rh because of their reduced overpotentials which are less than 0.5 V. Therefore,our findings pave guidance for designing Cu-BTC derivatives in overall water splitting.展开更多
In response to the challenges of sand production and high water cut during the exploitation of oil reservoirs in unconsolidated sandstones,a novel sand-water dual-control functional polymer,PDSM,was synthesized using ...In response to the challenges of sand production and high water cut during the exploitation of oil reservoirs in unconsolidated sandstones,a novel sand-water dual-control functional polymer,PDSM,was synthesized using acrylamide(AM),methacryloxyethyltrimethyl ammonium chloride(DMC),and styrene monomer(SM)as raw materials.The chemical structure and thermal stability of PDSM were verified by1H-NMR,FT-IR,and TGA analyses.To evaluate its performance,functional polymers PDM and PSM,containing only DMC or SM,respectively,were used as control groups.The study systematically investigated the static adsorption,sand production,sand leakage time,standard water-oil resistance ratio,and water cut reduction performance of PDSM.The results demonstrated that,due to the synergistic effect of functional monomers DMC and SM,PDSM exhibited superior dual-control over sand and water compared to PDM and PSM.PDSM enhanced wettability properties reduce the contact angle of the water phase on oil-wet rock surfaces to 64.0°,facilitating better adsorption of polymer molecules on the rock surface and achieving a static adsorption capacity of 14.6 mg/g.PDSM effectively bridges/bundles sand grains through SM and DMC,increasing resistance to fluid erosion.At a flow rate of 100 mL/min,sand production was only 0.026 g/L,surpassing the"Q/SH 10202377-2020"standard for sand inhibitors,which defines"excellent"performance as having a sand production rate of≤0.05 g/L.PDSM forms an adsorption layer(polymer concentrated layer)on the rock surface,expanding when in contact with water and shrinking when in contact with oil,thereby significantly reducing the permeability of the water layer without affecting the permeability of the oil layer.The standard water-oil resistance ratio was measured at 5.41,and the watercut of produced fluid was reduced by 18.6%.These findings provide new theoretical insights and technical guidance for developing dual-function sand-water control agents.展开更多
Stable carbon isotopes(δ^(13)C)are extensively utilized to study intrinsic water use efficiency(iWUE)at the leaf-scale in terrestrial ecosystems,serving as a crucial metric for assessing plant adaptation to climate c...Stable carbon isotopes(δ^(13)C)are extensively utilized to study intrinsic water use efficiency(iWUE)at the leaf-scale in terrestrial ecosystems,serving as a crucial metric for assessing plant adaptation to climate change.However,there is currently a lack of consensus regarding the leaf-scale iWUE variation characteristics among different functional types.In this study,we measured theδ^(13)Cleaf and iWUE values of different functional plants(i.e.,life forms,leaf types,and mycorrhizal types)from 120 species across distinct habitat types(i.e.,hillside,nearpeak,and peak)in a subtropical forest on the western slope of Wuyi Mountains,southern China.The results showed that theδ^(13)Cleaf values of plants on the western slope of Wuyi Mountains ranged from-34.63‰to-30.04‰,and iWUE ranged from 5.93μmol mol^(-1)to 57.34μmol mol^(-1).Theδ^(13)Cleaf and iWUE values differed significantly among plant life forms,following the order of herbs>vine plants>shrubs>trees.Theδ^(13)Cleaf and iWUE values of ectomycorrhizal(ECM)species were greater than those of arbuscular mycorrhizal(AM)species despite there being no significant difference between plants with different leaf types(Simple leaves(SL)vs.Compound leaves(CL)).From the hillside to the peak,both at the community level and at the species level,theδ^(13)C values of leaves and iWUE values of plants exhibited an upward trend.The regression analysis revealed that leaf-scale iWUE was significantly negatively correlated with soil water content and significantly positively correlated with leaf phosphorus content.The findings indicated that leaf carbon isotope fractionation and corresponding iWUE can be influenced by life form,mycorrhizal type,and soil water availability.These insights provide a deeper understanding of the coupling mechanisms of carbon,water,and nutrients among different functional plant types in subtropical forests,and offer insights into predicting plant adaptability under climate change.展开更多
Bifunctional Ir catalysts for proton exchange membrane(PEM)water electrolysis offer transformative potential by streamlining electrolyzer while achieving efficient performance remains challenging due to the distinct c...Bifunctional Ir catalysts for proton exchange membrane(PEM)water electrolysis offer transformative potential by streamlining electrolyzer while achieving efficient performance remains challenging due to the distinct conditions required for oxygen and hydrogen evolution reaction(OER and HER).Herein,we propose a theory-directed design of Ir-based bifunctional catalysts,Ir nanoparticles supported on mesoporous carbon spheres embedded with MoSe_(2)(Ir/MoSe_(2)@MCS),leveraging a work function(WF)-induced spontaneous built-in electric field to enhance catalytic performance.They demonstrate exceptional kinetics for both OER and HER,and potential application in the practical PEM electrolyzer,showcasing the effectiveness of this innovative approach.Low overpotentials of 252 mV for OER and 28 mV for HER to drive 10 mA cm^(-2)were observed,and the PEM electrolyzer showed the current density of 2 A cm^(-2)at 1.87 V and maintained stable activity at 1.65 V for over 30 h to deliver 1 A cm^(-2).Density functional theory calculations reveal that the WF difference at Ir/MoSe_(2)interface induces a spontaneous built-in electric field with asymmetric charge distributions,that modulate the electronic environment and d-band center of Ir promoting bifunctional active phase formation.This significantly lowers reaction barriers for water splitting by balancing intermediate adsorption,endowing the bifunctional activity.展开更多
Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor...Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor dispersion.Here,we report a strategy for the photosynergetic electrochemical functionalization of graphene(EFG).By using chloride ion(Cl^(-))as the intercalation anions and co-reactants,the electrogenerated radicals confined in the expanded graphite layers enable efficient radical addition reaction,thus grasping crystallineperfect EFG.We found that the ultraviolet irradiation and applied voltage have increased the surface/interface concentration of Cl,thus boosting the functionalization of graphene.Theoretical calculation and experimental results verified the oxygen evolution reaction(OER)on EFG has been improved by regulating the doping of chlorine atoms.In addition,the reduced interlayer distance and enhanced electrostatic repulsion near the basal plane endow the fabricated EFG-based membrane with high salt retention.This work highlights a method for the in situ functionalization of graphene and the subsequent applications in OER and water desalination.展开更多
A series of dual-extended-polyhedral metal-organic frameworks(MOFs)was constructed based on the 14-coordinated Cu_(24)-MOP-1(MOP=metal-organic polyhedron)supermolecular building blocks(SBBs)with enhanced stability and...A series of dual-extended-polyhedral metal-organic frameworks(MOFs)was constructed based on the 14-coordinated Cu_(24)-MOP-1(MOP=metal-organic polyhedron)supermolecular building blocks(SBBs)with enhanced stability and tunable functionality for high water uptake efficiency and capacity.Exceptional water stability was demonstrated by the retention of chemical integrity and crystallinity of USC-CP-5(where USC-CP stands for University of South China coordination polymer)after exposure to boiling water for 24 h.Functionalization with-Cl,-OCH_(3),-OH,and-NH_(2)groups of USC-CP-5 resulted in water uptake capacities of 450,460,490,and 590 cm^(3)·g^(-1) at relative pressure(P/P_(0))=0.9,respectively.This performance is ascribed to both the increased hydrophilicity of the ligands and stronger hydrogen bonding.Intriguingly,high-temperature activated USC-5-NH_(2)exhibits a significant water uptake of 38.5 wt.%at P/P_(0)=0.3 and releases 0.44 L·kg^(-1) water between 25 and 65℃.This water release process is reversible for at least 100 cycles with minimal weight loss of only 1.6 wt.%.Consequently,USC-5-NH_(2)holds considerable potential for harvesting and releasing atmospheric water in arid desert regions,powered by solar energy.展开更多
On basis of test information, the research performed analysis on water production function models of two crops, which indicated that water model of crops in whole growth stage and water model of crops indifferent grow...On basis of test information, the research performed analysis on water production function models of two crops, which indicated that water model of crops in whole growth stage and water model of crops indifferent growth stages have consistency as well as differences, providing references for optimization of irrigation water. Meanwhile, the research analyzed the deficiency of optimization on irrigation water for crops just by Jensen model.展开更多
According to the current situation and development planning of water resources in Jiangjin District of Three Gorge Reservoir Area at the upper reaches of Yangtze River,by combining with social needs,through the survey...According to the current situation and development planning of water resources in Jiangjin District of Three Gorge Reservoir Area at the upper reaches of Yangtze River,by combining with social needs,through the survey on pollution source and analysis of water quality,based on the Report of Water Function Division of Jiangjin District(2005) ,the adjustment and revision have been conducted on water function divisions,and corresponding protection targets and countermeasures for water resources have been proposed,so that the water function division can comply with the development situation of Jiangjin District,providing a reliable reference for the protection and reasonable utilization of water resources,enhancing the unified and effective supervision of water resources,promoting the sustainable use of water resources in Jiangjin District,and ensuring the sustainable development of regional society and environment.展开更多
Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to o...Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to obtain the crop water sensitivity index, the salinity sensitivity index, and other parameters. Using data collected during 35 years to calculate the 10-day mean precipitation and evaporation, the variation in soil salinity concentrations and in the yields of winter wheat and cotton were simulated for 49 irrigation scheduling that were combined from 7 irrigation schemes over 3 irrigation dates and 7 salinity concentrations of saline irrigation water (fresh water and 6 levels of saline water). Comparison of predicted results with irrigation data obtained from a large area of the field showed that the model was valid and reliable. Based on the analysis of the investment cost of the irrigation that employed deep tube wells or shallow tube wells, a saline water irrigation schedule and a corresponding strategy for groundwater development and utilization were proposed. For wheat or cotton, if the salinity concentration was higher than 7.0 g L-1 in groundwater, irrigation was needed with only fresh water; if about 5.0 g L-1, irrigation was required twice with fresh water and once with saline water; and if not higher than 3.0 g L-1, irrigation could be solely with saline water.展开更多
For computation of large amplitude motions of ships fastened to a dock, a fast evaluation scheme is implemented for computation of the time-domain Green function for finite water depth. Based on accurate evaluation of...For computation of large amplitude motions of ships fastened to a dock, a fast evaluation scheme is implemented for computation of the time-domain Green function for finite water depth. Based on accurate evaluation of the Green function directly, a fast approximation method for the Green function is developed by use of Chebyshev polynomials. Examinations are carried out of the accuracy of the Green function and its derivatives from the scheme. It is shown that when an appropriate number of polynomial terms are used, very accurate approximation can be obtained.展开更多
Layered double hydroxides(LDHs),a class of anionic clays consisting of brucite-like host layers and interlayer anions,have been widely investigated in the last decade due to their promising applications in many areas ...Layered double hydroxides(LDHs),a class of anionic clays consisting of brucite-like host layers and interlayer anions,have been widely investigated in the last decade due to their promising applications in many areas such as catalysis,ion separation and adsorption.Owing to the highly tunable compositi on and uniform distribution of metal cations in the brucite-like layers,as well as the facile exchangeability of intercalated anions,LDHs can be modified and functionalized to form various nanostructures/composites through versatile processes such as anion intercalation and exfoliation,decoration of nanoparticles,selfassembly with other two-dimensional(2D)materials,and controlled growth on conductive supports(e.g.,nanowire arrays,nano tubes,3D foams).In this article,we briefly review the recent advances on both the LDH nano structures and functionalized composites toward the applications in energy conversion,especially for water oxidation.展开更多
In recent decades, the control of floods is an efficient management practice for the rehabilitation of rangelands in most arid and semiarid areas. To evaluate the benefits, we used the Landscape Function Analysis （LF...In recent decades, the control of floods is an efficient management practice for the rehabilitation of rangelands in most arid and semiarid areas. To evaluate the benefits, we used the Landscape Function Analysis （LFA） method to assess the function of patches and qualitative capability of a rangeland ecosystem in Gareh By- gone region, Fars province, southwestern Iran. Landscape functionality depends on soil, water and nutrient （col- lectively called ＂resources＂） conservation and use within a given ecosystem. Many landscapes are naturally het- erogeneous in terms of resource control and possess patches, where resources tend to accumulate, and in- ter-patches. Assessing rangeland health and function of landscape patches in response to environment and man- agement can give rise to correct management decisions for qualitative improvement of the ecosystem. Therefore, our study area was divided into two parts, i.e. water spreading and control parts, and sampling was done using LFA method in each part separately. Structural parameters, including the number, length and width of patches, and the mean length of inter-patches, were determined by the method to characterize the functional status of the monitoring sites. For each patch/inter-patch type identified in the transect organization log, we recorded its soil surface proper- ties classified according to the Soil Surface Assessment Method. The density, canopy cover and composition of plants were then assessed. The results showed that the number of ecological patches and their dimensions were significantly increased in the water spreading site. Soil stability and the values of nutrient cycling indices were in- creased but the infiltration values were decreased in the water spreading site. It could be related to the effect of suspended materials transported by floods to the soils in the study area. The improvement of ecological patches and rangeland ecosystem was achieved where water spreading systems were practiced. Therefore it can be con- cluded that water spreading as a management plan plays an important role in arid land ecosystem functionality.展开更多
Rational design of highly efficient,robust and nonprecious electrocatalysts for the oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is highly demanded and challenging.H...Rational design of highly efficient,robust and nonprecious electrocatalysts for the oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is highly demanded and challenging.Here,heterostructural Co_(3O)_(4)@Ni_(2)P arrays with numerous reaction sites,unique interfacial electronic structure and fast charge transfer kinetics are developed as electrocatalysts for rechargeable Zn-air batteries and overall water splitting.Both density functional theory calculation and X-ray absorption fine structure analysis manifest that the synergistic structural and abundant electronic modulations interfaces are formed,thus simultaneously promoting the electrocatalytic kinetics,activities and stabilities.Specifically,it can achieve an ultralow overpotential of 270 m V and 28 m V at 10 m A cm^(-2) for OER and HER,respectively.The water electrolyzer delivers a current density of 10 m A cm^(-2) at 1.563 V;furthermore,rechargeable Zn-air batteries triggered by this heterostructure can achieve excellent cyclic stability of 177 h(2 h per cycle)at 10 m A cm^(-2);both devices are superior to the Pt/C+Ir/C.This work not only designs an efficient trifunctional electrocatalyst but also paves an avenue to understand the heterostructure engineering for catalysts development and disclose the underlying relationship of interfacial electronic structures and catalytic properties.展开更多
Water function classification is to divide the waters in a basin or a region into different water function regions according to the natural features such as water resources condition, physical geographical location, e...Water function classification is to divide the waters in a basin or a region into different water function regions according to the natural features such as water resources condition, physical geographical location, environmental condition, etc. and social features such as the status quo of development and utilization, the requirement of social and economic development on water quantity and quality etc. Water function division has not ever been carried out in China and no ready-made theory and method can be complied with, in the meantime, it is a fundamental work with strong practical function. Therefore, the basic concept and theory foundation and research method are put forward on the base of summary of water resources management and developed and will be perfected in practice process of water function division. The Yangtze function zone covers the Yangtze river basin, the Lancang river basin and the rivers in the western area of the Lancang river in Southwest China. According to the technical outline of national water function division and combined with division practice of the Yangtze function zone, this paper presents the scope determination, procedure and method of water function division.展开更多
This study is conducted to investigate the function of paddy fields for flood reduction under different water saving irrigation techniques. A daily water balance component data including rainfall, percolation, and ove...This study is conducted to investigate the function of paddy fields for flood reduction under different water saving irrigation techniques. A daily water balance component data including rainfall, percolation, and overflow through the paddy field levee were collected from experimental paddy rice fields during rainy season cultivation. Results show that paddy field was very effective in flood reduction. More than 40% of rainfall could be stored in the paddy fields. However, the effectiveness of paddy fields in flood reduction was highly depends on the WSI technique used. Semi dry cultivation technique was the most effective one in terms of flood reduction. It retained the rainfall up to 55.7% (365 mm) of the total rainfall (636 mm) without reducing the yield. In terms of flood volume reduction, the alternate wetting and drying performed similarly with traditional continuous flooding, i.e., 37.2% and 40.8%, respectively.展开更多
Optimized calculation of 35 dialkyl phenyl phosphate compounds （OPs） was carded out at the B3LYP/6-31G^＊ level in Gaussian 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, ...Optimized calculation of 35 dialkyl phenyl phosphate compounds （OPs） was carded out at the B3LYP/6-31G^＊ level in Gaussian 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting n-octanol/water partition coefficients （lgKow） of OPs. The new model achieved in this work contains three variables, i.e., molecular volume （Vm）, dipole moment of the molecules （μ） and enthalpy （H^0）. For this model, R^2 = 0.9167 and SD = 0.31 at large t values. In addition, the variation inflation factors （VIF） of variables are all close to 1.0, suggesting high accuracy of the predicting model. And the results of cross-validation test （q^2 = 0.8993） and method validation also showed the model of this study exhibited optimum stability and better predictive power than that from semi-empirical method. The model achieved can be used to predict IgKow of congeneric compounds.展开更多
Based on Investigation and Assessment on Rational Exploitation and Utilization of Groundwater Resources in Typical Areas of the Hexi Corridor, the thesis studies on groundwater and environmental problems arising from ...Based on Investigation and Assessment on Rational Exploitation and Utilization of Groundwater Resources in Typical Areas of the Hexi Corridor, the thesis studies on groundwater and environmental problems arising from the large-scale agricultural development projects in Shule River Basin. The thesis analyzes problems in exploiting and utilizing water resources, defines the function zoning of groundwater resources in key areas and evaluates them. Finally, the thesis uses three-dimensional unsteady flow simulation and regional social and economic development plan to study on the allocation of groundwater in Shule River Basin. A proposal for rational allocation of Shule River Basin water resources has been put forward.展开更多
In this work, an extended Jacobian elliptic function expansion method is proposed for constructing the exact solutions of nonlinear evolution equations. The validity and reliability of the method are tested by its app...In this work, an extended Jacobian elliptic function expansion method is proposed for constructing the exact solutions of nonlinear evolution equations. The validity and reliability of the method are tested by its applications to the system of shallow water wave equations and modified Liouville equation which play an important role in mathematical physics.展开更多
The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the w...The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020,and investigated the main driving factors(precipitation,potential evapotranspiration,land use/land cover change,and inflow from the Ili River)of the water conservation variation based on the linear regression,piecewise linear regression,and Pearson's correlation coefficient analyses.The results indicated that from 1975 to 2020,the water yield and water conservation in the IRD showed a decreasing trend,and the spatial distribution pattern was"high in the east and low in the west";overall,the water conservation of all land use types decreased slightly.The water conservation volume of grassland was the most reduced,although the area of grassland increased owing to the increased inflow from the Ili River.At the same time,the increased inflow has led to the expansion of wetland areas,the improvement of vegetation growth,and the increase of regional evapotranspiration,thus resulting in an overall reduction in the water conservation.The water conservation depth and precipitation had similar spatial distribution patterns;the change in climate factors was the main reason for the decline in the water conservation function in the delta.The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash,promoted vegetation restoration,and had a positive effect on the water conservation;however,this positive effect cannot offset the negative effect of enhanced evapotranspiration.These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.展开更多
基金supported by the National Key R&D Program of China(No.2022YFC3203602)the Natural Science Foundation of China(No.52370018)+1 种基金Shaanxi Provincial Youth Innovation Team Project(No.22JP040)Shaanxi Provincial Key Scientific and Technological Innovation Team(No.2023-CX-TD-32).
文摘During the initial impoundment period of a canyon-shaped reservoir,the water body fluctuated violently regarding water level,hydrological condition,and thermal stratification.These variations may alter the structure of phytoplankton community,resulting in algal blooms and seriously threatening the ecological security of the reservoir.It is of great significance to understand the continuous changes of phytoplankton in the initial impoundment period for the protection of reservoir water quality.Therefore,a two-year in-situ monitoring study was conducted on water quality and phytoplankton in a representative canyonshaped reservoir named Sanhekou and the interannual changes of phytoplankton community and its response to environmental changes during the initial impoundment period were discussed at taxonomic versus functional classification levels.The results showed that the total nitrogen and permanganate index levels were relatively high in the first year due to rapid water storage and heavy rainfall input,and the more stable hydrological conditions in the second year promoted the increase of algae density and the transformation of community,and the proportion of cyanobacteria increased significantly.The succession order of phytoplankton in the first year of the initial impoundment periodwas Chlorophyta-Bacillariophyta-Chlorophyta,or J/F/X1-P/MP/W1-A/X1/MP,respectively.And the succession order in the second year was Cyanobacteria/Chlorophyta-Bacillariophyta-Chlorophyta,or L_(M)/G/P-P/A/X1-X1/J/G.Water temperature,relativewater column stability,mixing depth,and pHwere crucial factors affecting phytoplankton community succession.This study revealed the interannual succession law and driving factors of phytoplankton in the initial impoundment period and provided an important reference for the operation management and ecological protection of canyon-shaped reservoirs.
基金the financial support from National Natural Science Foundation of China (No. 21503097)Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX23_3905)。
文摘Metal-organic framework(MOF) has been widely applied in photocatalysis, which is significant for addressing energy crises and environmental issues. Based on density functional theory calculations,the performances of Cu-BTC, a copper-based MOF, and its derivatives Cu TM-BTC via the substitution of transition metal(TM) elements at the Cu site for photocatalytic overall water splitting(POWS) have been studied. POWS of Cu-BTC suffers from the sluggish hydrogen evolution reaction due to the large overpotential of 2.02 V and limited solar utilization due to a wide HOMO-LUMO gap of 4.11 e V. Via TM substitution, the HOMO-LUMO gap narrows but still satisfies the redox potentials when taken 3d-TM of Cr, Fe, Co or Ni, 4d-TM of Rh or Pd, or 5d-TM of Re or Pt into consideration, benefiting for the light absorption. Furthermore, Cr and Re could serve as active sites for hydrogen evolution with remarkably lowered overpotentials of 0.79 V and 0.28 V, respectively;similarly, oxygen evolution activities could be enhanced by Fe, Co and Rh because of their reduced overpotentials which are less than 0.5 V. Therefore,our findings pave guidance for designing Cu-BTC derivatives in overall water splitting.
基金supported by the National Natural Science Foundation of China(General Program)(Grant No.52474071)the financial support from the China Scholarship Council(TM.Lei,No.202406450004)。
文摘In response to the challenges of sand production and high water cut during the exploitation of oil reservoirs in unconsolidated sandstones,a novel sand-water dual-control functional polymer,PDSM,was synthesized using acrylamide(AM),methacryloxyethyltrimethyl ammonium chloride(DMC),and styrene monomer(SM)as raw materials.The chemical structure and thermal stability of PDSM were verified by1H-NMR,FT-IR,and TGA analyses.To evaluate its performance,functional polymers PDM and PSM,containing only DMC or SM,respectively,were used as control groups.The study systematically investigated the static adsorption,sand production,sand leakage time,standard water-oil resistance ratio,and water cut reduction performance of PDSM.The results demonstrated that,due to the synergistic effect of functional monomers DMC and SM,PDSM exhibited superior dual-control over sand and water compared to PDM and PSM.PDSM enhanced wettability properties reduce the contact angle of the water phase on oil-wet rock surfaces to 64.0°,facilitating better adsorption of polymer molecules on the rock surface and achieving a static adsorption capacity of 14.6 mg/g.PDSM effectively bridges/bundles sand grains through SM and DMC,increasing resistance to fluid erosion.At a flow rate of 100 mL/min,sand production was only 0.026 g/L,surpassing the"Q/SH 10202377-2020"standard for sand inhibitors,which defines"excellent"performance as having a sand production rate of≤0.05 g/L.PDSM forms an adsorption layer(polymer concentrated layer)on the rock surface,expanding when in contact with water and shrinking when in contact with oil,thereby significantly reducing the permeability of the water layer without affecting the permeability of the oil layer.The standard water-oil resistance ratio was measured at 5.41,and the watercut of produced fluid was reduced by 18.6%.These findings provide new theoretical insights and technical guidance for developing dual-function sand-water control agents.
基金supported by the Open Research Fund of Jiangxi Provincial Academy of Water Resources Sciences(2022SKTR05&2022SKTR03)the National Natural Science Foundation of China(42067049&42367049),the Jiangxi Provincial Natural Science Foundation(20242BAB25350)+5 种基金the Research Project of the Jiangxi Provincial Department of Forestry(CXZX(2025)14 and JXTG(2023)15)the Ganpo Juncai Plan(QN2023018)the Ganpo Yingcai Plan(gpyc20240038)the Double Thousand Plan of Jiangxi Province(jxsq2023102213 and jxsq2023102214)the Jiangxi Province“Science and Technology+Water Resources”Joint Plan Project(2023KSG01001)the Major Discipline Academic and Technical Leaders Training Program of Jiangxi Province(20243BCE51025).
文摘Stable carbon isotopes(δ^(13)C)are extensively utilized to study intrinsic water use efficiency(iWUE)at the leaf-scale in terrestrial ecosystems,serving as a crucial metric for assessing plant adaptation to climate change.However,there is currently a lack of consensus regarding the leaf-scale iWUE variation characteristics among different functional types.In this study,we measured theδ^(13)Cleaf and iWUE values of different functional plants(i.e.,life forms,leaf types,and mycorrhizal types)from 120 species across distinct habitat types(i.e.,hillside,nearpeak,and peak)in a subtropical forest on the western slope of Wuyi Mountains,southern China.The results showed that theδ^(13)Cleaf values of plants on the western slope of Wuyi Mountains ranged from-34.63‰to-30.04‰,and iWUE ranged from 5.93μmol mol^(-1)to 57.34μmol mol^(-1).Theδ^(13)Cleaf and iWUE values differed significantly among plant life forms,following the order of herbs>vine plants>shrubs>trees.Theδ^(13)Cleaf and iWUE values of ectomycorrhizal(ECM)species were greater than those of arbuscular mycorrhizal(AM)species despite there being no significant difference between plants with different leaf types(Simple leaves(SL)vs.Compound leaves(CL)).From the hillside to the peak,both at the community level and at the species level,theδ^(13)C values of leaves and iWUE values of plants exhibited an upward trend.The regression analysis revealed that leaf-scale iWUE was significantly negatively correlated with soil water content and significantly positively correlated with leaf phosphorus content.The findings indicated that leaf carbon isotope fractionation and corresponding iWUE can be influenced by life form,mycorrhizal type,and soil water availability.These insights provide a deeper understanding of the coupling mechanisms of carbon,water,and nutrients among different functional plant types in subtropical forests,and offer insights into predicting plant adaptability under climate change.
文摘Bifunctional Ir catalysts for proton exchange membrane(PEM)water electrolysis offer transformative potential by streamlining electrolyzer while achieving efficient performance remains challenging due to the distinct conditions required for oxygen and hydrogen evolution reaction(OER and HER).Herein,we propose a theory-directed design of Ir-based bifunctional catalysts,Ir nanoparticles supported on mesoporous carbon spheres embedded with MoSe_(2)(Ir/MoSe_(2)@MCS),leveraging a work function(WF)-induced spontaneous built-in electric field to enhance catalytic performance.They demonstrate exceptional kinetics for both OER and HER,and potential application in the practical PEM electrolyzer,showcasing the effectiveness of this innovative approach.Low overpotentials of 252 mV for OER and 28 mV for HER to drive 10 mA cm^(-2)were observed,and the PEM electrolyzer showed the current density of 2 A cm^(-2)at 1.87 V and maintained stable activity at 1.65 V for over 30 h to deliver 1 A cm^(-2).Density functional theory calculations reveal that the WF difference at Ir/MoSe_(2)interface induces a spontaneous built-in electric field with asymmetric charge distributions,that modulate the electronic environment and d-band center of Ir promoting bifunctional active phase formation.This significantly lowers reaction barriers for water splitting by balancing intermediate adsorption,endowing the bifunctional activity.
基金supported by the Natural Science Foundation of Guangxi Province(2021GXNSFBA220077,GUIKE AD23026050)National Natural Science Foundation of China(22102035 and 22162006)Innovation Project of Guangxi Graduate Education(XYCBZ2024021).
文摘Chemical functionalization of graphene is a topic of paramount importance to broaden its applications in chemistry,physics,and biological science but remains a great challenge due to its low chemical activity and poor dispersion.Here,we report a strategy for the photosynergetic electrochemical functionalization of graphene(EFG).By using chloride ion(Cl^(-))as the intercalation anions and co-reactants,the electrogenerated radicals confined in the expanded graphite layers enable efficient radical addition reaction,thus grasping crystallineperfect EFG.We found that the ultraviolet irradiation and applied voltage have increased the surface/interface concentration of Cl,thus boosting the functionalization of graphene.Theoretical calculation and experimental results verified the oxygen evolution reaction(OER)on EFG has been improved by regulating the doping of chlorine atoms.In addition,the reduced interlayer distance and enhanced electrostatic repulsion near the basal plane endow the fabricated EFG-based membrane with high salt retention.This work highlights a method for the in situ functionalization of graphene and the subsequent applications in OER and water desalination.
基金supported by the National Natural Science Foundation of China(Nos.11375082,22271189,12405385,92356301,and 21522105)the Hunan Provincial Natural Science Foundation of China(No.2021JJ30565)+5 种基金the Science and Technology Commission of Shanghai Municipality(Nos.21XD1402300,21JC1401700,and 21DZ2260400)the supports by the Double First-Class Initiative Fund of ShanghaiTech University(No.SYLDX0052022)the Analytical Instrumentation Center(No.SPST-AIC10112914)for adsorption measurementthe staff at BL17B1 beamline of the National Facility for Protein Science in Shanghai(NFPS),Shanghai Advanced Research Institute,CAS,for providing beamtime for single-crystal X-ray diffraction data collectionthe project CICECO-Aveiro Institute of Materials,Grants(Nos.UIDB/50011/2020,UIDP/50011/2020,and LA/P/0006/2020)financed by national funds through the FCT/MEC(PIDDAC).
文摘A series of dual-extended-polyhedral metal-organic frameworks(MOFs)was constructed based on the 14-coordinated Cu_(24)-MOP-1(MOP=metal-organic polyhedron)supermolecular building blocks(SBBs)with enhanced stability and tunable functionality for high water uptake efficiency and capacity.Exceptional water stability was demonstrated by the retention of chemical integrity and crystallinity of USC-CP-5(where USC-CP stands for University of South China coordination polymer)after exposure to boiling water for 24 h.Functionalization with-Cl,-OCH_(3),-OH,and-NH_(2)groups of USC-CP-5 resulted in water uptake capacities of 450,460,490,and 590 cm^(3)·g^(-1) at relative pressure(P/P_(0))=0.9,respectively.This performance is ascribed to both the increased hydrophilicity of the ligands and stronger hydrogen bonding.Intriguingly,high-temperature activated USC-5-NH_(2)exhibits a significant water uptake of 38.5 wt.%at P/P_(0)=0.3 and releases 0.44 L·kg^(-1) water between 25 and 65℃.This water release process is reversible for at least 100 cycles with minimal weight loss of only 1.6 wt.%.Consequently,USC-5-NH_(2)holds considerable potential for harvesting and releasing atmospheric water in arid desert regions,powered by solar energy.
文摘On basis of test information, the research performed analysis on water production function models of two crops, which indicated that water model of crops in whole growth stage and water model of crops indifferent growth stages have consistency as well as differences, providing references for optimization of irrigation water. Meanwhile, the research analyzed the deficiency of optimization on irrigation water for crops just by Jensen model.
基金Supported by Chongqing City Sponsored Project of 2011 That is"Revision of Water Function Division of Chongqing City" [No. 3 of 2011 of Yu Water Resources]~~
文摘According to the current situation and development planning of water resources in Jiangjin District of Three Gorge Reservoir Area at the upper reaches of Yangtze River,by combining with social needs,through the survey on pollution source and analysis of water quality,based on the Report of Water Function Division of Jiangjin District(2005) ,the adjustment and revision have been conducted on water function divisions,and corresponding protection targets and countermeasures for water resources have been proposed,so that the water function division can comply with the development situation of Jiangjin District,providing a reliable reference for the protection and reasonable utilization of water resources,enhancing the unified and effective supervision of water resources,promoting the sustainable use of water resources in Jiangjin District,and ensuring the sustainable development of regional society and environment.
基金Project supported by the National Natural Science Foundation of China (Nos. 50339030 and 90202001).
文摘Using a crop-water-salinity production function and a soil-water-salinity dynamic model, optimal irrigation scheduling was developed to maximize net return per irrigated area. Plot and field experiments were used to obtain the crop water sensitivity index, the salinity sensitivity index, and other parameters. Using data collected during 35 years to calculate the 10-day mean precipitation and evaporation, the variation in soil salinity concentrations and in the yields of winter wheat and cotton were simulated for 49 irrigation scheduling that were combined from 7 irrigation schemes over 3 irrigation dates and 7 salinity concentrations of saline irrigation water (fresh water and 6 levels of saline water). Comparison of predicted results with irrigation data obtained from a large area of the field showed that the model was valid and reliable. Based on the analysis of the investment cost of the irrigation that employed deep tube wells or shallow tube wells, a saline water irrigation schedule and a corresponding strategy for groundwater development and utilization were proposed. For wheat or cotton, if the salinity concentration was higher than 7.0 g L-1 in groundwater, irrigation was needed with only fresh water; if about 5.0 g L-1, irrigation was required twice with fresh water and once with saline water; and if not higher than 3.0 g L-1, irrigation could be solely with saline water.
文摘For computation of large amplitude motions of ships fastened to a dock, a fast evaluation scheme is implemented for computation of the time-domain Green function for finite water depth. Based on accurate evaluation of the Green function directly, a fast approximation method for the Green function is developed by use of Chebyshev polynomials. Examinations are carried out of the accuracy of the Green function and its derivatives from the scheme. It is shown that when an appropriate number of polynomial terms are used, very accurate approximation can be obtained.
基金supported by the National Natural Science Foundation of China(Grant Nos.21505050,51672109)the Dispatch of Faculty Abroad of the University of Jinan+2 种基金the Natural Science Foundation of Shandong Province(Grant No.ZR2016FM30)supported in part by the WPI-MANA,Ministry of Education,Culture,Sports,Science and Technology,Japansupport from JSPS KAKENNHI(18H03869)
文摘Layered double hydroxides(LDHs),a class of anionic clays consisting of brucite-like host layers and interlayer anions,have been widely investigated in the last decade due to their promising applications in many areas such as catalysis,ion separation and adsorption.Owing to the highly tunable compositi on and uniform distribution of metal cations in the brucite-like layers,as well as the facile exchangeability of intercalated anions,LDHs can be modified and functionalized to form various nanostructures/composites through versatile processes such as anion intercalation and exfoliation,decoration of nanoparticles,selfassembly with other two-dimensional(2D)materials,and controlled growth on conductive supports(e.g.,nanowire arrays,nano tubes,3D foams).In this article,we briefly review the recent advances on both the LDH nano structures and functionalized composites toward the applications in energy conversion,especially for water oxidation.
文摘In recent decades, the control of floods is an efficient management practice for the rehabilitation of rangelands in most arid and semiarid areas. To evaluate the benefits, we used the Landscape Function Analysis （LFA） method to assess the function of patches and qualitative capability of a rangeland ecosystem in Gareh By- gone region, Fars province, southwestern Iran. Landscape functionality depends on soil, water and nutrient （col- lectively called ＂resources＂） conservation and use within a given ecosystem. Many landscapes are naturally het- erogeneous in terms of resource control and possess patches, where resources tend to accumulate, and in- ter-patches. Assessing rangeland health and function of landscape patches in response to environment and man- agement can give rise to correct management decisions for qualitative improvement of the ecosystem. Therefore, our study area was divided into two parts, i.e. water spreading and control parts, and sampling was done using LFA method in each part separately. Structural parameters, including the number, length and width of patches, and the mean length of inter-patches, were determined by the method to characterize the functional status of the monitoring sites. For each patch/inter-patch type identified in the transect organization log, we recorded its soil surface proper- ties classified according to the Soil Surface Assessment Method. The density, canopy cover and composition of plants were then assessed. The results showed that the number of ecological patches and their dimensions were significantly increased in the water spreading site. Soil stability and the values of nutrient cycling indices were in- creased but the infiltration values were decreased in the water spreading site. It could be related to the effect of suspended materials transported by floods to the soils in the study area. The improvement of ecological patches and rangeland ecosystem was achieved where water spreading systems were practiced. Therefore it can be con- cluded that water spreading as a management plan plays an important role in arid land ecosystem functionality.
基金the National Natural Science Foundation of China(Nos.22179014 and 21603019)the Fundamental Research Funds for the Central Universities(No.2021CDJQY-051)+1 种基金the Key Program for International Science and Technology Cooperation Projects of Ministry of Science and Technology of China(No.2016YFE0125900)the Hundred Talents Program of Chongqing University。
文摘Rational design of highly efficient,robust and nonprecious electrocatalysts for the oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)is highly demanded and challenging.Here,heterostructural Co_(3O)_(4)@Ni_(2)P arrays with numerous reaction sites,unique interfacial electronic structure and fast charge transfer kinetics are developed as electrocatalysts for rechargeable Zn-air batteries and overall water splitting.Both density functional theory calculation and X-ray absorption fine structure analysis manifest that the synergistic structural and abundant electronic modulations interfaces are formed,thus simultaneously promoting the electrocatalytic kinetics,activities and stabilities.Specifically,it can achieve an ultralow overpotential of 270 m V and 28 m V at 10 m A cm^(-2) for OER and HER,respectively.The water electrolyzer delivers a current density of 10 m A cm^(-2) at 1.563 V;furthermore,rechargeable Zn-air batteries triggered by this heterostructure can achieve excellent cyclic stability of 177 h(2 h per cycle)at 10 m A cm^(-2);both devices are superior to the Pt/C+Ir/C.This work not only designs an efficient trifunctional electrocatalyst but also paves an avenue to understand the heterostructure engineering for catalysts development and disclose the underlying relationship of interfacial electronic structures and catalytic properties.
文摘Water function classification is to divide the waters in a basin or a region into different water function regions according to the natural features such as water resources condition, physical geographical location, environmental condition, etc. and social features such as the status quo of development and utilization, the requirement of social and economic development on water quantity and quality etc. Water function division has not ever been carried out in China and no ready-made theory and method can be complied with, in the meantime, it is a fundamental work with strong practical function. Therefore, the basic concept and theory foundation and research method are put forward on the base of summary of water resources management and developed and will be perfected in practice process of water function division. The Yangtze function zone covers the Yangtze river basin, the Lancang river basin and the rivers in the western area of the Lancang river in Southwest China. According to the technical outline of national water function division and combined with division practice of the Yangtze function zone, this paper presents the scope determination, procedure and method of water function division.
文摘This study is conducted to investigate the function of paddy fields for flood reduction under different water saving irrigation techniques. A daily water balance component data including rainfall, percolation, and overflow through the paddy field levee were collected from experimental paddy rice fields during rainy season cultivation. Results show that paddy field was very effective in flood reduction. More than 40% of rainfall could be stored in the paddy fields. However, the effectiveness of paddy fields in flood reduction was highly depends on the WSI technique used. Semi dry cultivation technique was the most effective one in terms of flood reduction. It retained the rainfall up to 55.7% (365 mm) of the total rainfall (636 mm) without reducing the yield. In terms of flood volume reduction, the alternate wetting and drying performed similarly with traditional continuous flooding, i.e., 37.2% and 40.8%, respectively.
基金the State Science Foundation of China (No. 20477018)
文摘Optimized calculation of 35 dialkyl phenyl phosphate compounds （OPs） was carded out at the B3LYP/6-31G^＊ level in Gaussian 98 program. Based on the theoretical linear solvation energy relationship （TLSER） model, the obtained parameters were taken as theoretical descriptors to establish the novel QSPR model for predicting n-octanol/water partition coefficients （lgKow） of OPs. The new model achieved in this work contains three variables, i.e., molecular volume （Vm）, dipole moment of the molecules （μ） and enthalpy （H^0）. For this model, R^2 = 0.9167 and SD = 0.31 at large t values. In addition, the variation inflation factors （VIF） of variables are all close to 1.0, suggesting high accuracy of the predicting model. And the results of cross-validation test （q^2 = 0.8993） and method validation also showed the model of this study exhibited optimum stability and better predictive power than that from semi-empirical method. The model achieved can be used to predict IgKow of congeneric compounds.
基金the project Survey and Assessment of Water Resources Exploitation and Utilization in Characteristic Areas of the Hexi Corridor
文摘Based on Investigation and Assessment on Rational Exploitation and Utilization of Groundwater Resources in Typical Areas of the Hexi Corridor, the thesis studies on groundwater and environmental problems arising from the large-scale agricultural development projects in Shule River Basin. The thesis analyzes problems in exploiting and utilizing water resources, defines the function zoning of groundwater resources in key areas and evaluates them. Finally, the thesis uses three-dimensional unsteady flow simulation and regional social and economic development plan to study on the allocation of groundwater in Shule River Basin. A proposal for rational allocation of Shule River Basin water resources has been put forward.
文摘In this work, an extended Jacobian elliptic function expansion method is proposed for constructing the exact solutions of nonlinear evolution equations. The validity and reliability of the method are tested by its applications to the system of shallow water wave equations and modified Liouville equation which play an important role in mathematical physics.
基金funded by the National Natural Science Foundation of China(42071245)the Xinjiang Uygur Autonomous Region Innovation Environment Construction Special Project&Science and Technology Innovation Base Construction Project(PT2107)+2 种基金the Third Xinjiang Comprehensive Scientific Survey Project Sub-topic(2021xjkk140305)the Tianshan Talent Training Program of Xinjiang Uygur Autonomous Region(2022TSYCLJ0011)the K.C.Wong Education Foundation(GJTD-2020-14).
文摘The Ili River Delta(IRD)is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia.In this study,we selected the IRD as a typical research area,and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs(InVEST)model.We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020,and investigated the main driving factors(precipitation,potential evapotranspiration,land use/land cover change,and inflow from the Ili River)of the water conservation variation based on the linear regression,piecewise linear regression,and Pearson's correlation coefficient analyses.The results indicated that from 1975 to 2020,the water yield and water conservation in the IRD showed a decreasing trend,and the spatial distribution pattern was"high in the east and low in the west";overall,the water conservation of all land use types decreased slightly.The water conservation volume of grassland was the most reduced,although the area of grassland increased owing to the increased inflow from the Ili River.At the same time,the increased inflow has led to the expansion of wetland areas,the improvement of vegetation growth,and the increase of regional evapotranspiration,thus resulting in an overall reduction in the water conservation.The water conservation depth and precipitation had similar spatial distribution patterns;the change in climate factors was the main reason for the decline in the water conservation function in the delta.The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash,promoted vegetation restoration,and had a positive effect on the water conservation;however,this positive effect cannot offset the negative effect of enhanced evapotranspiration.These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.
