The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sed...The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.展开更多
Several new techniques in the field of heat transfer in fluids have opened new avenues for studying the heat transfer effects in nanofluids and thermodynamic flow parameters, leading to novel applications. There have ...Several new techniques in the field of heat transfer in fluids have opened new avenues for studying the heat transfer effects in nanofluids and thermodynamic flow parameters, leading to novel applications. There have been studies on nanofluids, including metal, ceramic and magnetic nanoparticles mixed with base fluids such as Water, Kerosene, and Ethylene glycol. However, research on fluids employing semiconductor nanoparticles as supplements to base fluids to generate nanofluids and hybrid nanofluids is limited. For the investigation, Gallium nitrite, a binary semiconductor with excellent heat convection, is together with Cu metal nanoparticles and Al<sub>2</sub>O<sub>3</sub> ceramic nanoparticles separately in the base fluid Ethylene glycol (EG) to form hybrid nanofluids. The effects of convective boundary conditions, thermal radiation, heat source/sink, suction/injection, and activation energy on three-dimensional Williamson MHD hybrid nanofluid flow of Cu + GaN + EG, Al<sub>2</sub>O<sub>3</sub> + GaN + EG, and Cu + Al<sub>2</sub>O<sub>3</sub> + EG are investigated on a stretched sheet with porosity. A similarity transformation is performed on the governing equations to transform them into dimensionless ordinary differential equations ODEs. Numerical analysis is carried out in MATLAB utilizing bvp5c and the shooting technique. The variations of velocity, temperature, and concentration profiles as a function of different physical effects are presented graphically with dimensionless parameters and explained the variations scientifically. As varied with different parameters, the values of the Skin-friction coefficient, Nusselt number, and Sherwood number are mentioned in the table.展开更多
Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data,...Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) sum mer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and ifs neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo-China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.展开更多
Ascertaining the relationship between "source-sink" landscape and non-point source(NPS) pollution is crucial for reducing NPS pollution, however, it is not easy to realize this target on cell unit scale. To ...Ascertaining the relationship between "source-sink" landscape and non-point source(NPS) pollution is crucial for reducing NPS pollution, however, it is not easy to realize this target on cell unit scale. To reveal the relationships between "sourcesink" landscape and NPS pollution based on cell units of a small catchment in the Three Gorges Reservoir Region(TGRR), the runoff and nutrient yields were simulated first by rainfall events on a cell unit scale based on the Annualized AGricultural Non-Point Source Pollution Model(AnnAGNPS). Landscape structure and pattern were quantified with "sourcesink" landscape indicators based on cell units including landscape area indices and locationweighted landscape indices. The results showed that:the study case of small Wangjiagou catchment highlighted a good prediction capability of runoff and nutrient export by the AnnAGNPS model. Throughout the catchment, the spatial distribution trends of four location-weighted landscape indices were similar to the trends of simulated total nitrogen(TN) and total phosphorus(TP), which highlighted the importance of spatial arrangement of "source" and "sink" landscape types in a catchment when estimating pollutant loads. Results by Pearson correlation analysis indicated that the location-weighted landscape index provided a more comprehensive account of multiple factors, and can better reflect NPS-related nutrient loss than other landscape indices applied in single-factor analysis. This study provides new findings for applying the "source-sink" landscape indices based on cell units in small catchments to explain the effect of "source-sink" landscape on nutrient export based on cell unit, and helps improve the understanding of the correlation between "source-sink" landscape and NPS pollution.展开更多
The source-sink relationship determines the ultimate grain yield.We investigated the genetic basis of the relationship between source and sink and yield potential in rice.In two environments,we identified quantitative...The source-sink relationship determines the ultimate grain yield.We investigated the genetic basis of the relationship between source and sink and yield potential in rice.In two environments,we identified quantitative trait loci(QTL)associated with sink capacity(total spikelet number per panicle and thousand-grain weight),source leaf(flag leaf length,flag leaf width and flag leaf area),source-sink relationship(total spikelet number to flag leaf area ratio)and yield-related traits(filled grain number per panicle,panicle number per plant,grain yield per plant,biomass per plant,and harvest index)by genome-wide association analysis using 272 Xian(indica)accessions.The panel showed substantial variation for all traits in the two environments and revealed complex phenotypic correlations.A total of 70 QTL influencing the 11 traits were identified using 469,377 high-quality SNP markers.Five QTL were detected consistently in four chromosomal regions in both environments.Five QTL clusters simultaneously affected source,sink,source–sink relationship,and grain yield traits,probably explaining the genetic basis of significant correlations of grain yield with source and sink traits.We selected 24 candidate genes in the four consistent QTL regions by identifying linkage disequilibrium(LD)blocks associated with significant SNPs and performing haplotype analysis.The genes included one cloned gene(NOG1)and three newly identified QTL(qHI6,qTGW7,and qFLA8).These results provide a theoretical basis for high-yield rice breeding by increasing and balancing source–sink relationships using marker-assisted selection.展开更多
The apparent heat sources (?Q1 ?) and moisture sinks (?Q2 ?) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May 1 to August 31, 1998. It is found that the formation...The apparent heat sources (?Q1 ?) and moisture sinks (?Q2 ?) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May 1 to August 31, 1998. It is found that the formation and distribution of the atmospheric heat sources are important for the monsoon onset. The earlier onset of the SCS monsoon is the result of enduring atmospheric heating in the Indo–China Peninsula and South China areas. The atmospheric heating firstly appears in the Indo–China Peninsula area and the sensible heat is the major one. The 30–50 day periodic oscillation of atmospheric heat sources between the SCS area and the western Pacific warm pool has a reverse phase distribution before the middle of July and the low frequency oscillation of heat sources in SCS area has an obvious longitudinal propagation. The 30–50 day low frequency oscillation has vital modificatory effects on the summer monsoon evolution during 1998. Key words Apparent heat sources - Apparent moisture sinks - The South China Sea monsoon - Diagnostic Study Sponsored by the National Key Project of Fundamental Research “ SCSMEX” and the Research Fund for the Doctoral Program of Higher Education: “ Study of the Air-sea Interaction in the SCS Monsoon Region”.展开更多
Global climate change has become a major concern worldwide. The spatio-temporal characteristics of net ecosystem productivity(NEP), which represents carbon sequestration capacity and directly describes the qualitative...Global climate change has become a major concern worldwide. The spatio-temporal characteristics of net ecosystem productivity(NEP), which represents carbon sequestration capacity and directly describes the qualitative and quantitative characteristics of carbon sources/sinks(C sources/sinks), are crucial for increasing C sinks and reducing C sources. In this study, field sampling data, remote sensing data, and ground meteorological observation data were used to estimate the net primary productivity(NPP) in the Inner Mongolia grassland ecosystem(IMGE) from 2001 to 2012 using a light use efficiency model. The spatio-temporal distribution of the NEP in the IMGE was then determined by estimating the NPP and soil respiration from 2001 to 2012. This research also investigated the response of the NPP and NEP to the main climatic variables at the spatial and temporal scales from 2001 to 2012. The results showed that most of the grassland area in Inner Mongolia has functioned as a C sink since 2001 and that the annual carbon sequestration rate amounts to 0.046 Pg C/a. The total net C sink of the IMGE over the 12-year research period reached 0.557 Pg C. The carbon sink area accounted for 60.28% of the total grassland area and the sequestered 0.692 Pg C, whereas the C source area accounted for 39.72% of the total grassland area and released 0.135 Pg C. The NPP and NEP of the IMGE were more significantly correlated with precipitation than with temperature, showing great potential for C sequestration.展开更多
Wetlands play an important role in the global carbon cycle, but there are still considerable uncertainties in the estimation of wetland carbon storage and a dispute on whether wetlands are carbon sources or carbon sin...Wetlands play an important role in the global carbon cycle, but there are still considerable uncertainties in the estimation of wetland carbon storage and a dispute on whether wetlands are carbon sources or carbon sinks. Xiaoxing’anling are one of several concentrated distribution areas of forested wetland in China, but the carbon storage and carbon sink/source of forested wetlands in this area is unclear. We measured the ecosystem carbon storage (vegetation and soil), annual net carbon sequestration of vegetation and annual carbon emissions of soil heterotrophic respiration of five typical forested wetland types (alder swamp, white birch swamp, larch swamp, larch fen, and larch bog) distributed along a moisture gradient in this area in order to reveal the spatial variations of their carbon storage and quantitatively evaluate their position as carbon sink or source according to the net carbon balance of the ecosystems. The results show that the larch fen had high carbon storage (448.8 t ha^(−1)) (6.8% higher than the larch bog and 10.5–30.1% significantly higher than other three wetlands (P < 0.05), the white birch swamp and larch bog were medium carbon storage ecosystems (406.3 and 420.1 t ha^(−1)) (12.4–21.8% significantly higher than the other two types (P < 0.0 5), while the alder swamp and larch swamp were low in carbon storage (345.0 and 361.5 t ha^(−1), respectively). The carbon pools of the five wetlands were dominated by their soil carbon pools (88.5–94.5%), and the vegetation carbon pool was secondary (5.5–11.5%). At the same time, their ecosystem net carbon balances were positive (0.1–0.6 t ha^(−1) a^(−1)) because the annual net carbon sequestration of vegetation (4.0–4.5 t ha^(−1) a^(−1)) were higher than the annual carbon emissions of soil heterotrophic respiration (CO_(2) and CH_(4)) (3.8–4.4 t ha^(−1) a^(−1)) in four wetlands, (the alder swamp being the exception), so all four were carbon sinks while only the alder swamp was a source of carbon emissions (− 2.1 t ha^(−1) a^(−1)) due to a degraded tree layer. Our results demonstrate that these forested wetlands were generally carbon sinks in the Xiaoxing’anling, and there was obvious spatial variation in carbon storage of ecosystems along the moisture gradient.展开更多
Using the summer (June to August) monthly mean data of the National Centers for Environmental Predictions (NCEP) - National Center for Atmospheric Research (NCAR) reanalysis from 1980 to 1997, atmospheric heat sources...Using the summer (June to August) monthly mean data of the National Centers for Environmental Predictions (NCEP) - National Center for Atmospheric Research (NCAR) reanalysis from 1980 to 1997, atmospheric heat sources and moisture sinks are calculated. Anomalous circulation and the vertically integrated heat source with the vertical integrated moisture sink and outgoing longwave radiation (OLR) flux are examined based upon monthly composites for 16 great wet-spells and 8 great dry-spells over the middle-lower reaches of the Yangtze River. The wind anomaly exhibits prominent differences between the great wet-spell and the great dry-spell over the Yangtze River Valley. For the great wet-spell, the anomalous southerly from the Bay of Bengal and the South China Sea and the anomalous northerly over North China enhanced low-level convergence toward a narrow latitudinal belt area (the middle-lower reaches of the Yangtze River). The southerly anomaly is connected with an anticyclonic anomalous circulation system centered at 22 degreesN, 140 degreesE and the northerly anomaly is associated with a cyclonic anomalous circulation system centered at the Japan Sea. In the upper level, the anomalous northwesterly between an anticyclonic anomalous system with the center at 23 degreesN, 105 degreesE and a cyclonic anomalous system with the center at Korea diverged over the middle-lower reaches of the Yangtze River. On the contrary, for the great dry-spell, the anomalous northerly over South China and the anomalous southerly over North China diverged from the Yangtze River Valley in the low level. The former formed in the western part of a cyclonic anomalous system centered at 23 degreesN, 135 degreesE. The latter was located in the western ridge of an anticyclonic anomalous system in the northwestern Pacific. The upper troposphere showed easterly anomaly that converged over the middle-lower reaches of the Yangtze River. A cyclonic anomalous system in South China and an anticyclonic system centered in the Japan Sea enhanced the easterly. Large atmospheric heat source anomalies of opposite signs existed over the western Pacific - the South China Sea, with negative in the great wet-spell and positive in the great dry-spell. The analysis of heat source also revealed positive anomalous heat sources during the great wet-spell and negative anomalous heat sources during the great dry-spell over the Yangtze River valley. The changes of the moisture sink and OLR were correspondingly altered, implying the change of heat source anomaly is due to the latent heat releasing of convective activity. Over the southeastern Tibetan Plateau- the Bay of Bengal, the analysis of heat source shows positive anomalous heat sources during the great wet-spell and negative anomalous heat sources during the great dry-spell because of latent heating change. The change of divergent wind coexisted with the change of heat source. In the great wet-spell, southerly divergent wind anomaly in the low level and northerly divergent wind anomaly in high-level are seen over South China. These divergent wind anomalies are helpful to the low-level convergence anomaly and high-level divergence anomaly over the Yangtze River valley. The low-level northerly divergent wind anomaly and high-level southerly divergent wind anomaly over South China reduced the low-level convergence and high-level divergence over the Yangtze River valley during the great dry-spell.展开更多
Three indica restorer lines （Mianhui 725, Shuhui 527, Shuhui 881）, an American rice variety Lemont and a javanica rice variety Xiangdali were crossed with japonica Kitaake, and five F1 hybrids were obtained to study...Three indica restorer lines （Mianhui 725, Shuhui 527, Shuhui 881）, an American rice variety Lemont and a javanica rice variety Xiangdali were crossed with japonica Kitaake, and five F1 hybrids were obtained to study the photosynthetic and agronomic traits. The data on photosynthetic characteristics indicated that the net photosynthetic rate （Pn） of the five F1 hybrids was significantly higher than that of their parents （or one of them） under high photosynthetic flux density （PFD）; while the overall performance of hybrids was better than their respective parents in apparent quantum yield （AQY）, carboxylation efficiency （CE） and CO2 compensation point （CCP）. Moreover, the photosynthetic performance of the five F1 were different due to the variation in heredity and the typical indica-japonica hybrids, Mianhui 725/Kitaake and Shuhui 527/Kitaake, were better than the others on this aspect. The agronomic traits revealed that the five F1 exhibited different heterosis, with Shuhui 881/Kitaake the largest sink followed by Mianhui 725/Kitaake, Shuhui 527/Kitaake, Lemont/Kitaake and Xiangdali/Kitaake. The production potential of indica-japonica hybrids was higher than that of the other two hybrids, which was consistent with the performance of Pn. However, the superior trait of indica-japonica hybrids on sink size has not been fully turned into high yield because of abnormal seed setting. Therefore, attention should be paid to the proper genome coordination and appropriate genetic distance so as to achieve super high yielding.展开更多
The East China Sea(ECS) is a river-dominated epicontinental sea, linking the Asian continent to the northwestern Pacific via the large rivers originating from Tibetan Plateau. The relevant huge influx of riverine detr...The East China Sea(ECS) is a river-dominated epicontinental sea, linking the Asian continent to the northwestern Pacific via the large rivers originating from Tibetan Plateau. The relevant huge influx of riverine detritus has developed unique sedimentary systems in the ECS during the Quaternary, offering ideal terrestrial archives for reconstructing Quaternary paleoenvironmental changes and studying land-sea interactions. Overall, two characteristic river systems dominate the sedimentary systems and sediment source to sink transport patterns in the ECS, represented by the Changjiang(Yangtze River) and Huanghe(Yellow River) for the large river system and Taiwan rivers for the small river system. Given this, the sediments derived from both river systems bear distinct features in terms of parent rock lithology, provenance weathering and sediment transport. Previous studies mostly focus on either the ‘source' discrimination or the ‘sink' records of the sedimentary system in the ECS, while the source to sink process linking the land and sea, in particular its time scale, has been poorly understood. Here we introduce a newly-developed dating technique, the ‘comminution age' method, which offers a quantitative constraint on the time scale of sediment transfer from its ultimate source to the final depositional sink. This novel method is of great significance for improving our understanding on the earth surface processes including tectonic-climate driven weathering, and sediment recycling in relation to landscape evolution and marine environmental changes. The application of comminution age method in the ECS will provide important constraints on sediment source-to-sink process and more evidences for the construction of late Quaternary paleoenvironmental changes under these unique sedimentary systems.展开更多
The convection of a Maxwell fluid over a stretching porous surface with a heat source/sink in the presence of nanoparticles is investigated. The Lie symmetry group transformations are used to convert the boundary laye...The convection of a Maxwell fluid over a stretching porous surface with a heat source/sink in the presence of nanoparticles is investigated. The Lie symmetry group transformations are used to convert the boundary layer equations into coupled nonlinear ordinary differential equations. The ordinary differential equations are solved numerically by the Bvp4c with MATLAB, which is a collocation method equivalent to the fourth-order mono-implicit Runge-Kutta method. Furthermore, more attention is paid to the effects of the physical parameters, especially the parameters related to nanoparticles, on the temperature and concentration distributions with consideration of permeability and the heat source/sink.展开更多
The effects of viscous dissipation and heat source/sink on fully developed mixed convection for the laminar flow in a parallel-plate vertical channel are investigated. The plate exchanges heat with an external fluid. ...The effects of viscous dissipation and heat source/sink on fully developed mixed convection for the laminar flow in a parallel-plate vertical channel are investigated. The plate exchanges heat with an external fluid. Both conditions of equal and different reference temperatures of the external fluid are considered. First, the simple cases of the negligible Brinkman number or the negligible Grashof number are solved analytically. Then, the combined effects of buoyancy forces and viscous dissipation in the presence of heat source/sink are analyzed by a perturbation series method valid for small values of the perturbation parameter. To relax the conditions on the perturbation parameter, the velocity and temperature fields are solved by using the Runge-Kutta fourth-order method with the shooting technique. The velocity, temperature, skin friction, and Nusselt num- bers at the plates are discussed numerically and presented through graphs.展开更多
This study explored the ecological effects of the transformation of carbon source and carbon sink in wetlands, that were discussed from four aspects: atmosphere, ocean, plants and soil. The results showed that the wet...This study explored the ecological effects of the transformation of carbon source and carbon sink in wetlands, that were discussed from four aspects: atmosphere, ocean, plants and soil. The results showed that the wetland changed from carbon sink to carbon source, which led to the increase of CO_2 emissions in the atmosphere and the intensification of greenhouse effect, which made the earth face the threat of global warming. At the same time, the content of CO_2 in seawater is increased; the pH value of seawater decreases; the balance of seawater acid-base is destroyed; and the ocean acidification is caused.展开更多
Research on the distribution of mantle CO_(2)should involve comprehensive analysis from CO_(2)source to accumulation.The crust-mantle pathway system is the key controlling factor of the distribution of mantle CO_(2),b...Research on the distribution of mantle CO_(2)should involve comprehensive analysis from CO_(2)source to accumulation.The crust-mantle pathway system is the key controlling factor of the distribution of mantle CO_(2),but has received little attention.The pathway system and controlling factors of CO_(2)distribution in the Bohai Sea are analyzed using data on fault styles and information on the mantle and lithosphere.The relation between volcanic rocks and the distribution of mantle CO_(2)is reassessed using age data for CO_(2)accumulations.The distribution of mantle CO_(2)is controlled by uplift of the asthenosphere and upper mantle,magma conduits in the mantle and fault systems in the crust.Uplifted regions of the asthenosphere are accumulation areas for CO_(2).The area with uplift of the Moho exhibits accumulation of mantle CO_(2)at depth.CO_(2)was mainly derived from vertical migration through the upper mantle and lower crust.The fault style in the upper crust controls the distance of horizontal migration and the locations of CO_(2)concentrations.The distribution of mantle CO_(2)and volcanic rocks are not the same,but both probably followed the same pathways sometimes.Mantle CO_(2)in the Bohai Sea is concentrated in the Bozhong sag and the surrounding area,particularly in a trap that formed before 5.1 Ma and is connected to crustal faults(the Bozhang faults)and lithospheric faults(the Tanlu faults).展开更多
Cd S/Mo S2,an extremely efficient photocatalyst,has been extensively used in hydrogen photoproduction and pollutant degradation.Cd S/Mo S2can be synthesized by a facile one-step hydrothermal process.However,the effect...Cd S/Mo S2,an extremely efficient photocatalyst,has been extensively used in hydrogen photoproduction and pollutant degradation.Cd S/Mo S2can be synthesized by a facile one-step hydrothermal process.However,the effect of the sulfur source on the synthesis of Cd S/Mo S2via one-step hydrothermal methods has seldom been investigated.We report herein a series of one-step hydrothermal preparations of Cd S/Mo S2using three different sulfur sources：thioacetamide,L-cysteine,and thiourea.The results revealed that the sulfur source strongly affected the crystallization,morphology,elemental composition and ultraviolet（UV）–visible-light-absorption ability of the Cd S/Mo S2.Among the investigated sulfur sources,thioacetamide provided the highest visible-light absorption ability for Cd S/Mo S2,with the smallest average particle size and largest surface area,resulting in the highest efficiency in Methylene Blue（MB）degradation.The photocatalytic activity of Cd S/Mo S2synthesized from the three sulfur sources can be arranged in the following order：thioacetamideL-cysteinethiourea.The reaction rate constants（k）for thioacetamide,L-cysteine,and thiourea were estimated to be 0.0197,0.0140,and 0.0084 min^（-1）,respectively.However,thioacetamide may be limited in practical application in terms of its price and toxicity,while L-cysteine is relatively economical,less toxic and exhibited good photocatalytic degradation performance toward MB.展开更多
The soil type is a key factor influencing N(nitrogen)cycling in soil;however,gross N transformations and N_(2)O emission sources are still poorly understood.In this study,a laboratory 15N tracing experiment was carrie...The soil type is a key factor influencing N(nitrogen)cycling in soil;however,gross N transformations and N_(2)O emission sources are still poorly understood.In this study,a laboratory 15N tracing experiment was carried out at 60%WHC(water holding capacity)and 25℃to evaluate the gross N transformation rates and N_(2)O emission pathways in sandy loam and silt loam soils in a semi-arid region of Heilongjiang Province,China.The results showed that the gross rates of N mineralization,immobilization,and nitrification were 3.60,1.90,and 5.63 mg N/(kg·d)in silt loam soil,respectively,which were 3.62,4.26,and 3.13 times those in sandy loam soil,respectively.The ratios of the gross nitrification rate to the ammonium immobilization rate(n/ia)in sandy loam soil and silt loam soil were all higher than 1.00,whereas the n/ia in sandy loam soil(4.36)was significantly higher than that in silt loam soil(3.08).This result indicated that the ability of sandy loam soil to release and conserve the available N was relatively poor in comparison with silt loam soil,and the relatively strong nitrification rate compared to the immobilization rate may lead to N loss through NO_(3)–leaching.Under aerobic conditions,both nitrification and denitrification made contributions to N_(2)O emissions.Nitrification was the dominant pathway leading to N_(2)O production in soils and was responsible for 82.0%of the total emitted N_(2)O in sandy loam soil,which was significantly higher than that in silt loam soil(71.7%).However,the average contribution of denitrification to total N_(2)O production in sandy loam soil was 17.9%,which was significantly lower than that in silt loam soil(28.3%).These results are valuable for developing reasonable fertilization management and proposing effective greenhouse gas mitigation strategies in different soil types in semiarid regions.展开更多
With two-line hybrid rice Yangliangyou 6 （YLY6） and Liangyoupeijiu （LYPJ） and three-line hybrid rice Shanyou 63 （SY63） as materials, the source, sink and flow characteristics in association with grain filling we...With two-line hybrid rice Yangliangyou 6 （YLY6） and Liangyoupeijiu （LYPJ） and three-line hybrid rice Shanyou 63 （SY63） as materials, the source, sink and flow characteristics in association with grain filling were investigated. The seed-setting rate, grain filling degree and grain yield of YLY6 and SY63 were significantly higher than those of LYPJ. The export and transformation percentages of the matter in culms and sheaths of YLY6 and SY63 were significantly higher than those of LYPJ. Activities of sucrose synthase, adenosine diphosphoglucose pyrophosphorylase, starch synthase and starch branching enzyme in grains were higher for YLY6 and SY63 than for LYPJ, and were very significantly correlated with maximum grain filling rate, mean grain filling rate, grain filling degree and grain weight. The spikelet number, grain yield and total sink load per area of vascular bundle and phloem of YLY6 and SY63 were significantly smaller than those of LYPJ, and the greater the load, the lower seed-setting rate and the poorer grain filling. The transportation rate per area phloem of YLY6 was greater than that of LYPJ or SY63. The results suggest that YLY6 possesses strong source, great sink activity and efficient flow, which lay a physiological base for its high seed-setting rate and good grain filling.展开更多
Non-point source pollution is one of the primarily ecological issues affecting the Three Gorges Reservoir Area. In this paper, landscape resistance and motivation coefficient, which integrated various landscape elemen...Non-point source pollution is one of the primarily ecological issues affecting the Three Gorges Reservoir Area. In this paper, landscape resistance and motivation coefficient, which integrated various landscape elements, such as land use, soil, hydrology, topography, and vegetation, was established based on the effects of large-scale resistance and motivation on the formation of non-point source pollution. In addition, cost models of the landscape re- sistance and motivation coefficients were constructed based on the distances from the land- scape units to the sub-basin outlets in order to identify the ＂source＂ and ＂sink＂ patterns af- fecting the formation of non-point source pollution. The results indicated that the changes in the landscape resistance and motivation coefficients of the 16 sub-basins exhibited inverse relationships to their spatial distributions. The landscape resistance and motivation cost curves were more volatile than the landscape resistance and motivation coefficient curves. The landscape resistance and motivation cost trends of the 16 sub-basins became increas- ingly apparent along the flow of the Yangtze River. The landscape resistance and motivation cost models proposed in this paper could be used to identify large-scale non-point source pollution ＂source＂ and ＂sink＂ patterns. Moreover, the proposed model could be used to de- scribe the large-scale spatial characteristics of non-point source pollution formation based on ＂source＂ and ＂sink＂ landscape pattern indices, spatial localization, and landscape resistance and motivation coefficients.展开更多
基金supported by the National Natural Science Foundation(Nos.52000024 and 41907335)the Natural Science Foundation of Shanghai(No.23ZR1400700).
文摘The arsenic(As)release from sediments in great lakes is affected by various factors.In this study,the characteristics of As release fromsediments was investigated,and the As sources and sinks with the strengths in sediments from different areas(grass-type,algae-type,and grass-algae alternation areas)in great shallow lakes(Taihu Lake,China)were analyzed,and the influence of P competition in the process of As release was also studied.The results showed that changing trend of the values of equilibrium As concentration in sediments were consistent with the regional changes(0 to 28.12μg/L),and the sediments from algaetype areas had the higher values.The sediments from western lake and northwest lake bay were a strong As and a weak P source,and the north lake bay had the opposite trend of these two regions.Intense P source competition with As from the sediments occurred in algae-type areas.The grass-type areas had strong As and P retention capacities,indicating a sink role of sediment with high As and P sorption capacities.The degree of As and P saturation had similar trend in sediments,and the grass-type areas had the higher values,18.3%-21.4%and 15.31%-20.34%,respectively.Contribution analysis results showed that most of As release contribution was from the bottom(30-50 cm)sediments,and the surface(0-10 cm)sediments from algae-type areas contributed more to the overlying water than other region.
文摘Several new techniques in the field of heat transfer in fluids have opened new avenues for studying the heat transfer effects in nanofluids and thermodynamic flow parameters, leading to novel applications. There have been studies on nanofluids, including metal, ceramic and magnetic nanoparticles mixed with base fluids such as Water, Kerosene, and Ethylene glycol. However, research on fluids employing semiconductor nanoparticles as supplements to base fluids to generate nanofluids and hybrid nanofluids is limited. For the investigation, Gallium nitrite, a binary semiconductor with excellent heat convection, is together with Cu metal nanoparticles and Al<sub>2</sub>O<sub>3</sub> ceramic nanoparticles separately in the base fluid Ethylene glycol (EG) to form hybrid nanofluids. The effects of convective boundary conditions, thermal radiation, heat source/sink, suction/injection, and activation energy on three-dimensional Williamson MHD hybrid nanofluid flow of Cu + GaN + EG, Al<sub>2</sub>O<sub>3</sub> + GaN + EG, and Cu + Al<sub>2</sub>O<sub>3</sub> + EG are investigated on a stretched sheet with porosity. A similarity transformation is performed on the governing equations to transform them into dimensionless ordinary differential equations ODEs. Numerical analysis is carried out in MATLAB utilizing bvp5c and the shooting technique. The variations of velocity, temperature, and concentration profiles as a function of different physical effects are presented graphically with dimensionless parameters and explained the variations scientifically. As varied with different parameters, the values of the Skin-friction coefficient, Nusselt number, and Sherwood number are mentioned in the table.
基金the auspices of the National!(G1998040800)CAS's Key Project for Basic Research on the Tibetan Plateau! (KZ951-A1-204, KZ95T-
文摘Based on the 1961-1995 atmospheric apparent heat source/sink and the 1961-1990 snow-cover days and depth over the Qinghai-Xizang Plateau (QXP) and the 1961-1995 reanalysis data of NCEP/NCAR and the 1975-1994 OLR data, this paper discusses the interannual variability of the heat regime and its relation to atmospheric circulation It is shown that the interannual variability is pronounced, with maximal variability in spring and autumn, and the variability is heterogeneous horizontally. In the years with the weak (or strong) winter cold source, the deep trough over East Asia is to the east (or west) of its normal, which corresponds to strong (or weak) winter monsoon in East Asia. In the years with the strong (or weak) sum mer heat source, there exists an anomalous cyclone (or anticyclone) in the middle and lower troposphere over the QXP and ifs neighborhood and anomalous southwest (or northeast) winds over the Yangtze River valley of China, corresponding to strong (or weak) summer monsoon in East Asia. The summer heat source of the QXP is related to the intensity and position of the South Asia high. The QXP snow cover condition of April has a close relation to the heating intensity of summer. There is a remarkable negative correlation between the summer heat source of the QXP and the convection over the southeastern QXP, the Bay of Bengal, the Indo-China Peninsula, the southeastern Asia, the southwest part of China and the lower reaches of the Yangtze River and in the area from the Yellow Sea of China to the Sea of Japan.
基金supported by the National Natural Science Foundation of China (Nos. 41671291)
文摘Ascertaining the relationship between "source-sink" landscape and non-point source(NPS) pollution is crucial for reducing NPS pollution, however, it is not easy to realize this target on cell unit scale. To reveal the relationships between "sourcesink" landscape and NPS pollution based on cell units of a small catchment in the Three Gorges Reservoir Region(TGRR), the runoff and nutrient yields were simulated first by rainfall events on a cell unit scale based on the Annualized AGricultural Non-Point Source Pollution Model(AnnAGNPS). Landscape structure and pattern were quantified with "sourcesink" landscape indicators based on cell units including landscape area indices and locationweighted landscape indices. The results showed that:the study case of small Wangjiagou catchment highlighted a good prediction capability of runoff and nutrient export by the AnnAGNPS model. Throughout the catchment, the spatial distribution trends of four location-weighted landscape indices were similar to the trends of simulated total nitrogen(TN) and total phosphorus(TP), which highlighted the importance of spatial arrangement of "source" and "sink" landscape types in a catchment when estimating pollutant loads. Results by Pearson correlation analysis indicated that the location-weighted landscape index provided a more comprehensive account of multiple factors, and can better reflect NPS-related nutrient loss than other landscape indices applied in single-factor analysis. This study provides new findings for applying the "source-sink" landscape indices based on cell units in small catchments to explain the effect of "source-sink" landscape on nutrient export based on cell unit, and helps improve the understanding of the correlation between "source-sink" landscape and NPS pollution.
基金funded by the National Key Research and Development Program of China(2016YFD0100301)the National Natural Science Foundation of China(31671602)the Agricultural Science and Technology Innovation Program and the Cooperation and Innovation Mission(CAASZDXT2018001)
文摘The source-sink relationship determines the ultimate grain yield.We investigated the genetic basis of the relationship between source and sink and yield potential in rice.In two environments,we identified quantitative trait loci(QTL)associated with sink capacity(total spikelet number per panicle and thousand-grain weight),source leaf(flag leaf length,flag leaf width and flag leaf area),source-sink relationship(total spikelet number to flag leaf area ratio)and yield-related traits(filled grain number per panicle,panicle number per plant,grain yield per plant,biomass per plant,and harvest index)by genome-wide association analysis using 272 Xian(indica)accessions.The panel showed substantial variation for all traits in the two environments and revealed complex phenotypic correlations.A total of 70 QTL influencing the 11 traits were identified using 469,377 high-quality SNP markers.Five QTL were detected consistently in four chromosomal regions in both environments.Five QTL clusters simultaneously affected source,sink,source–sink relationship,and grain yield traits,probably explaining the genetic basis of significant correlations of grain yield with source and sink traits.We selected 24 candidate genes in the four consistent QTL regions by identifying linkage disequilibrium(LD)blocks associated with significant SNPs and performing haplotype analysis.The genes included one cloned gene(NOG1)and three newly identified QTL(qHI6,qTGW7,and qFLA8).These results provide a theoretical basis for high-yield rice breeding by increasing and balancing source–sink relationships using marker-assisted selection.
基金National Key Project of Fundamental Research u SCSMEX" the Research Fund for the Doctoral Program of Higher Education:" Stud
文摘The apparent heat sources (?Q1 ?) and moisture sinks (?Q2 ?) are calculated based on the reanalyzed data of the South China Sea Monsoon Experiment (SCSMEX) from May 1 to August 31, 1998. It is found that the formation and distribution of the atmospheric heat sources are important for the monsoon onset. The earlier onset of the SCS monsoon is the result of enduring atmospheric heating in the Indo–China Peninsula and South China areas. The atmospheric heating firstly appears in the Indo–China Peninsula area and the sensible heat is the major one. The 30–50 day periodic oscillation of atmospheric heat sources between the SCS area and the western Pacific warm pool has a reverse phase distribution before the middle of July and the low frequency oscillation of heat sources in SCS area has an obvious longitudinal propagation. The 30–50 day low frequency oscillation has vital modificatory effects on the summer monsoon evolution during 1998. Key words Apparent heat sources - Apparent moisture sinks - The South China Sea monsoon - Diagnostic Study Sponsored by the National Key Project of Fundamental Research “ SCSMEX” and the Research Fund for the Doctoral Program of Higher Education: “ Study of the Air-sea Interaction in the SCS Monsoon Region”.
基金National Basic Research Program of China(973 Program),No.2015CB452702,No.2012CB416906National Natural Science Foundation of China,No.41571098,No.41371196National Key Technology R&D Program,No.2013BAC03B04
文摘Global climate change has become a major concern worldwide. The spatio-temporal characteristics of net ecosystem productivity(NEP), which represents carbon sequestration capacity and directly describes the qualitative and quantitative characteristics of carbon sources/sinks(C sources/sinks), are crucial for increasing C sinks and reducing C sources. In this study, field sampling data, remote sensing data, and ground meteorological observation data were used to estimate the net primary productivity(NPP) in the Inner Mongolia grassland ecosystem(IMGE) from 2001 to 2012 using a light use efficiency model. The spatio-temporal distribution of the NEP in the IMGE was then determined by estimating the NPP and soil respiration from 2001 to 2012. This research also investigated the response of the NPP and NEP to the main climatic variables at the spatial and temporal scales from 2001 to 2012. The results showed that most of the grassland area in Inner Mongolia has functioned as a C sink since 2001 and that the annual carbon sequestration rate amounts to 0.046 Pg C/a. The total net C sink of the IMGE over the 12-year research period reached 0.557 Pg C. The carbon sink area accounted for 60.28% of the total grassland area and the sequestered 0.692 Pg C, whereas the C source area accounted for 39.72% of the total grassland area and released 0.135 Pg C. The NPP and NEP of the IMGE were more significantly correlated with precipitation than with temperature, showing great potential for C sequestration.
基金This project was supported fi nancially by the National Key Research and Development Program of China(2016YFA0600803)the National Natural Science Foundation of China(31370461).
文摘Wetlands play an important role in the global carbon cycle, but there are still considerable uncertainties in the estimation of wetland carbon storage and a dispute on whether wetlands are carbon sources or carbon sinks. Xiaoxing’anling are one of several concentrated distribution areas of forested wetland in China, but the carbon storage and carbon sink/source of forested wetlands in this area is unclear. We measured the ecosystem carbon storage (vegetation and soil), annual net carbon sequestration of vegetation and annual carbon emissions of soil heterotrophic respiration of five typical forested wetland types (alder swamp, white birch swamp, larch swamp, larch fen, and larch bog) distributed along a moisture gradient in this area in order to reveal the spatial variations of their carbon storage and quantitatively evaluate their position as carbon sink or source according to the net carbon balance of the ecosystems. The results show that the larch fen had high carbon storage (448.8 t ha^(−1)) (6.8% higher than the larch bog and 10.5–30.1% significantly higher than other three wetlands (P < 0.05), the white birch swamp and larch bog were medium carbon storage ecosystems (406.3 and 420.1 t ha^(−1)) (12.4–21.8% significantly higher than the other two types (P < 0.0 5), while the alder swamp and larch swamp were low in carbon storage (345.0 and 361.5 t ha^(−1), respectively). The carbon pools of the five wetlands were dominated by their soil carbon pools (88.5–94.5%), and the vegetation carbon pool was secondary (5.5–11.5%). At the same time, their ecosystem net carbon balances were positive (0.1–0.6 t ha^(−1) a^(−1)) because the annual net carbon sequestration of vegetation (4.0–4.5 t ha^(−1) a^(−1)) were higher than the annual carbon emissions of soil heterotrophic respiration (CO_(2) and CH_(4)) (3.8–4.4 t ha^(−1) a^(−1)) in four wetlands, (the alder swamp being the exception), so all four were carbon sinks while only the alder swamp was a source of carbon emissions (− 2.1 t ha^(−1) a^(−1)) due to a degraded tree layer. Our results demonstrate that these forested wetlands were generally carbon sinks in the Xiaoxing’anling, and there was obvious spatial variation in carbon storage of ecosystems along the moisture gradient.
基金Supported by National Key Programme for Developing Basic Sciences G1998040900 Part 1 and IAPInnovation Foundation 8-1308.
文摘Using the summer (June to August) monthly mean data of the National Centers for Environmental Predictions (NCEP) - National Center for Atmospheric Research (NCAR) reanalysis from 1980 to 1997, atmospheric heat sources and moisture sinks are calculated. Anomalous circulation and the vertically integrated heat source with the vertical integrated moisture sink and outgoing longwave radiation (OLR) flux are examined based upon monthly composites for 16 great wet-spells and 8 great dry-spells over the middle-lower reaches of the Yangtze River. The wind anomaly exhibits prominent differences between the great wet-spell and the great dry-spell over the Yangtze River Valley. For the great wet-spell, the anomalous southerly from the Bay of Bengal and the South China Sea and the anomalous northerly over North China enhanced low-level convergence toward a narrow latitudinal belt area (the middle-lower reaches of the Yangtze River). The southerly anomaly is connected with an anticyclonic anomalous circulation system centered at 22 degreesN, 140 degreesE and the northerly anomaly is associated with a cyclonic anomalous circulation system centered at the Japan Sea. In the upper level, the anomalous northwesterly between an anticyclonic anomalous system with the center at 23 degreesN, 105 degreesE and a cyclonic anomalous system with the center at Korea diverged over the middle-lower reaches of the Yangtze River. On the contrary, for the great dry-spell, the anomalous northerly over South China and the anomalous southerly over North China diverged from the Yangtze River Valley in the low level. The former formed in the western part of a cyclonic anomalous system centered at 23 degreesN, 135 degreesE. The latter was located in the western ridge of an anticyclonic anomalous system in the northwestern Pacific. The upper troposphere showed easterly anomaly that converged over the middle-lower reaches of the Yangtze River. A cyclonic anomalous system in South China and an anticyclonic system centered in the Japan Sea enhanced the easterly. Large atmospheric heat source anomalies of opposite signs existed over the western Pacific - the South China Sea, with negative in the great wet-spell and positive in the great dry-spell. The analysis of heat source also revealed positive anomalous heat sources during the great wet-spell and negative anomalous heat sources during the great dry-spell over the Yangtze River valley. The changes of the moisture sink and OLR were correspondingly altered, implying the change of heat source anomaly is due to the latent heat releasing of convective activity. Over the southeastern Tibetan Plateau- the Bay of Bengal, the analysis of heat source shows positive anomalous heat sources during the great wet-spell and negative anomalous heat sources during the great dry-spell because of latent heating change. The change of divergent wind coexisted with the change of heat source. In the great wet-spell, southerly divergent wind anomaly in the low level and northerly divergent wind anomaly in high-level are seen over South China. These divergent wind anomalies are helpful to the low-level convergence anomaly and high-level divergence anomaly over the Yangtze River valley. The low-level northerly divergent wind anomaly and high-level southerly divergent wind anomaly over South China reduced the low-level convergence and high-level divergence over the Yangtze River valley during the great dry-spell.
文摘Three indica restorer lines （Mianhui 725, Shuhui 527, Shuhui 881）, an American rice variety Lemont and a javanica rice variety Xiangdali were crossed with japonica Kitaake, and five F1 hybrids were obtained to study the photosynthetic and agronomic traits. The data on photosynthetic characteristics indicated that the net photosynthetic rate （Pn） of the five F1 hybrids was significantly higher than that of their parents （or one of them） under high photosynthetic flux density （PFD）; while the overall performance of hybrids was better than their respective parents in apparent quantum yield （AQY）, carboxylation efficiency （CE） and CO2 compensation point （CCP）. Moreover, the photosynthetic performance of the five F1 were different due to the variation in heredity and the typical indica-japonica hybrids, Mianhui 725/Kitaake and Shuhui 527/Kitaake, were better than the others on this aspect. The agronomic traits revealed that the five F1 exhibited different heterosis, with Shuhui 881/Kitaake the largest sink followed by Mianhui 725/Kitaake, Shuhui 527/Kitaake, Lemont/Kitaake and Xiangdali/Kitaake. The production potential of indica-japonica hybrids was higher than that of the other two hybrids, which was consistent with the performance of Pn. However, the superior trait of indica-japonica hybrids on sink size has not been fully turned into high yield because of abnormal seed setting. Therefore, attention should be paid to the proper genome coordination and appropriate genetic distance so as to achieve super high yielding.
基金supported by the Key Laboratory of Marine Hydrocarbon Resources and Environmental Geology (MRE201402)the National Natural Science Foundation of China (41306040, 41225020)the Foundation of Key Laboratory of Yangtze River Water Environment (YRWEF 201305)
文摘The East China Sea(ECS) is a river-dominated epicontinental sea, linking the Asian continent to the northwestern Pacific via the large rivers originating from Tibetan Plateau. The relevant huge influx of riverine detritus has developed unique sedimentary systems in the ECS during the Quaternary, offering ideal terrestrial archives for reconstructing Quaternary paleoenvironmental changes and studying land-sea interactions. Overall, two characteristic river systems dominate the sedimentary systems and sediment source to sink transport patterns in the ECS, represented by the Changjiang(Yangtze River) and Huanghe(Yellow River) for the large river system and Taiwan rivers for the small river system. Given this, the sediments derived from both river systems bear distinct features in terms of parent rock lithology, provenance weathering and sediment transport. Previous studies mostly focus on either the ‘source' discrimination or the ‘sink' records of the sedimentary system in the ECS, while the source to sink process linking the land and sea, in particular its time scale, has been poorly understood. Here we introduce a newly-developed dating technique, the ‘comminution age' method, which offers a quantitative constraint on the time scale of sediment transfer from its ultimate source to the final depositional sink. This novel method is of great significance for improving our understanding on the earth surface processes including tectonic-climate driven weathering, and sediment recycling in relation to landscape evolution and marine environmental changes. The application of comminution age method in the ECS will provide important constraints on sediment source-to-sink process and more evidences for the construction of late Quaternary paleoenvironmental changes under these unique sedimentary systems.
基金supported by the National Natural Science Foundation of China(No.11302024)the Fundamental Research Funds for the Central Universities(No.FRF-TP-15-036A3)+1 种基金the Beijing Higher Education Young Elite Teacher Project(No.YETP0387)the Foundation of the China Scholarship Council in 2014(No.154201406465041)
文摘The convection of a Maxwell fluid over a stretching porous surface with a heat source/sink in the presence of nanoparticles is investigated. The Lie symmetry group transformations are used to convert the boundary layer equations into coupled nonlinear ordinary differential equations. The ordinary differential equations are solved numerically by the Bvp4c with MATLAB, which is a collocation method equivalent to the fourth-order mono-implicit Runge-Kutta method. Furthermore, more attention is paid to the effects of the physical parameters, especially the parameters related to nanoparticles, on the temperature and concentration distributions with consideration of permeability and the heat source/sink.
基金University Grant Commission in New Delhi for the financial support under UGC-Major Research Project and Maulana Azad National Fellowship for Minority Students
文摘The effects of viscous dissipation and heat source/sink on fully developed mixed convection for the laminar flow in a parallel-plate vertical channel are investigated. The plate exchanges heat with an external fluid. Both conditions of equal and different reference temperatures of the external fluid are considered. First, the simple cases of the negligible Brinkman number or the negligible Grashof number are solved analytically. Then, the combined effects of buoyancy forces and viscous dissipation in the presence of heat source/sink are analyzed by a perturbation series method valid for small values of the perturbation parameter. To relax the conditions on the perturbation parameter, the velocity and temperature fields are solved by using the Runge-Kutta fourth-order method with the shooting technique. The velocity, temperature, skin friction, and Nusselt num- bers at the plates are discussed numerically and presented through graphs.
文摘This study explored the ecological effects of the transformation of carbon source and carbon sink in wetlands, that were discussed from four aspects: atmosphere, ocean, plants and soil. The results showed that the wetland changed from carbon sink to carbon source, which led to the increase of CO_2 emissions in the atmosphere and the intensification of greenhouse effect, which made the earth face the threat of global warming. At the same time, the content of CO_2 in seawater is increased; the pH value of seawater decreases; the balance of seawater acid-base is destroyed; and the ocean acidification is caused.
基金supported by the Major Program of the National Natural Science Foundation of China(41790453)the Natural Science Foundation of Jilin Province(20170101001JC)+1 种基金the National Natural Science Foundation of China(41472304)the National Science and Technology Major Project of the Ministry of Science and Technology of China(2016ZX05026-004-001)。
文摘Research on the distribution of mantle CO_(2)should involve comprehensive analysis from CO_(2)source to accumulation.The crust-mantle pathway system is the key controlling factor of the distribution of mantle CO_(2),but has received little attention.The pathway system and controlling factors of CO_(2)distribution in the Bohai Sea are analyzed using data on fault styles and information on the mantle and lithosphere.The relation between volcanic rocks and the distribution of mantle CO_(2)is reassessed using age data for CO_(2)accumulations.The distribution of mantle CO_(2)is controlled by uplift of the asthenosphere and upper mantle,magma conduits in the mantle and fault systems in the crust.Uplifted regions of the asthenosphere are accumulation areas for CO_(2).The area with uplift of the Moho exhibits accumulation of mantle CO_(2)at depth.CO_(2)was mainly derived from vertical migration through the upper mantle and lower crust.The fault style in the upper crust controls the distance of horizontal migration and the locations of CO_(2)concentrations.The distribution of mantle CO_(2)and volcanic rocks are not the same,but both probably followed the same pathways sometimes.Mantle CO_(2)in the Bohai Sea is concentrated in the Bozhong sag and the surrounding area,particularly in a trap that formed before 5.1 Ma and is connected to crustal faults(the Bozhang faults)and lithospheric faults(the Tanlu faults).
基金supported by the National Natural Science Foundation of China (No. 51478431)a Science and TechnologyPlanning Project from the Science and Technology Department in Zhejiang Province (No. 2014C33028)funding as a Xinmiao Talent Project of Zhejiang Province (No. 2016R408074)
文摘Cd S/Mo S2,an extremely efficient photocatalyst,has been extensively used in hydrogen photoproduction and pollutant degradation.Cd S/Mo S2can be synthesized by a facile one-step hydrothermal process.However,the effect of the sulfur source on the synthesis of Cd S/Mo S2via one-step hydrothermal methods has seldom been investigated.We report herein a series of one-step hydrothermal preparations of Cd S/Mo S2using three different sulfur sources：thioacetamide,L-cysteine,and thiourea.The results revealed that the sulfur source strongly affected the crystallization,morphology,elemental composition and ultraviolet（UV）–visible-light-absorption ability of the Cd S/Mo S2.Among the investigated sulfur sources,thioacetamide provided the highest visible-light absorption ability for Cd S/Mo S2,with the smallest average particle size and largest surface area,resulting in the highest efficiency in Methylene Blue（MB）degradation.The photocatalytic activity of Cd S/Mo S2synthesized from the three sulfur sources can be arranged in the following order：thioacetamideL-cysteinethiourea.The reaction rate constants（k）for thioacetamide,L-cysteine,and thiourea were estimated to be 0.0197,0.0140,and 0.0084 min^（-1）,respectively.However,thioacetamide may be limited in practical application in terms of its price and toxicity,while L-cysteine is relatively economical,less toxic and exhibited good photocatalytic degradation performance toward MB.
基金financed by the National Natural Science Foundation of China(41301345,41101284)。
文摘The soil type is a key factor influencing N(nitrogen)cycling in soil;however,gross N transformations and N_(2)O emission sources are still poorly understood.In this study,a laboratory 15N tracing experiment was carried out at 60%WHC(water holding capacity)and 25℃to evaluate the gross N transformation rates and N_(2)O emission pathways in sandy loam and silt loam soils in a semi-arid region of Heilongjiang Province,China.The results showed that the gross rates of N mineralization,immobilization,and nitrification were 3.60,1.90,and 5.63 mg N/(kg·d)in silt loam soil,respectively,which were 3.62,4.26,and 3.13 times those in sandy loam soil,respectively.The ratios of the gross nitrification rate to the ammonium immobilization rate(n/ia)in sandy loam soil and silt loam soil were all higher than 1.00,whereas the n/ia in sandy loam soil(4.36)was significantly higher than that in silt loam soil(3.08).This result indicated that the ability of sandy loam soil to release and conserve the available N was relatively poor in comparison with silt loam soil,and the relatively strong nitrification rate compared to the immobilization rate may lead to N loss through NO_(3)–leaching.Under aerobic conditions,both nitrification and denitrification made contributions to N_(2)O emissions.Nitrification was the dominant pathway leading to N_(2)O production in soils and was responsible for 82.0%of the total emitted N_(2)O in sandy loam soil,which was significantly higher than that in silt loam soil(71.7%).However,the average contribution of denitrification to total N_(2)O production in sandy loam soil was 17.9%,which was significantly lower than that in silt loam soil(28.3%).These results are valuable for developing reasonable fertilization management and proposing effective greenhouse gas mitigation strategies in different soil types in semiarid regions.
基金supported by the National Natural Science Foundation of China(30270778)Chinese Ministry of Science and Technology(2001BA507A-09-01-03,2004BA520A12-5).
文摘With two-line hybrid rice Yangliangyou 6 （YLY6） and Liangyoupeijiu （LYPJ） and three-line hybrid rice Shanyou 63 （SY63） as materials, the source, sink and flow characteristics in association with grain filling were investigated. The seed-setting rate, grain filling degree and grain yield of YLY6 and SY63 were significantly higher than those of LYPJ. The export and transformation percentages of the matter in culms and sheaths of YLY6 and SY63 were significantly higher than those of LYPJ. Activities of sucrose synthase, adenosine diphosphoglucose pyrophosphorylase, starch synthase and starch branching enzyme in grains were higher for YLY6 and SY63 than for LYPJ, and were very significantly correlated with maximum grain filling rate, mean grain filling rate, grain filling degree and grain weight. The spikelet number, grain yield and total sink load per area of vascular bundle and phloem of YLY6 and SY63 were significantly smaller than those of LYPJ, and the greater the load, the lower seed-setting rate and the poorer grain filling. The transportation rate per area phloem of YLY6 was greater than that of LYPJ or SY63. The results suggest that YLY6 possesses strong source, great sink activity and efficient flow, which lay a physiological base for its high seed-setting rate and good grain filling.
文摘Non-point source pollution is one of the primarily ecological issues affecting the Three Gorges Reservoir Area. In this paper, landscape resistance and motivation coefficient, which integrated various landscape elements, such as land use, soil, hydrology, topography, and vegetation, was established based on the effects of large-scale resistance and motivation on the formation of non-point source pollution. In addition, cost models of the landscape re- sistance and motivation coefficients were constructed based on the distances from the land- scape units to the sub-basin outlets in order to identify the ＂source＂ and ＂sink＂ patterns af- fecting the formation of non-point source pollution. The results indicated that the changes in the landscape resistance and motivation coefficients of the 16 sub-basins exhibited inverse relationships to their spatial distributions. The landscape resistance and motivation cost curves were more volatile than the landscape resistance and motivation coefficient curves. The landscape resistance and motivation cost trends of the 16 sub-basins became increas- ingly apparent along the flow of the Yangtze River. The landscape resistance and motivation cost models proposed in this paper could be used to identify large-scale non-point source pollution ＂source＂ and ＂sink＂ patterns. Moreover, the proposed model could be used to de- scribe the large-scale spatial characteristics of non-point source pollution formation based on ＂source＂ and ＂sink＂ landscape pattern indices, spatial localization, and landscape resistance and motivation coefficients.
