High temperature stress(HTS)on spring maize(Zea mays L.)during the filling stage is the key factor that limits the yield increase in the North China Plain(NCP).Subsoiling(SS)and ridge tillage(R)were introduced to enha...High temperature stress(HTS)on spring maize(Zea mays L.)during the filling stage is the key factor that limits the yield increase in the North China Plain(NCP).Subsoiling(SS)and ridge tillage(R)were introduced to enhance the ability of spring maize to resist HTS during the filling stage.The field experiments were conducted during the 2011 and 2012 maize growing seasons at Wuqiao County,Hebei Province,China.Compared with rotary tillage(RT),the net photosynthetic rate,stomatal conductance,transpiration rate,and chlorophyll relative content(SPAD)of maize leaves was increased by 40.0,42.6,12.8,and 29.7%under SS,and increased by 20.4,20.0,5.4,and 14.2%under R,repectively.However,the treatments reduce the intercellular CO2concentration under HTS.The SS and R treatments increased the relative water content(RWC)by 11.9 and6.2%,and the water use efficiency(WUE)by 24.3 and 14.3%,respectively,compared with RT.The SS treatment increased the root length density and soil moisture in the 0-80 cm soil profile,whereas the R treatment increased the root length density and soil moisture in the 0-40 cm soil profile compared with the RT treatment.Compared with 2011,the number of days with temperatures 33°C was more 2 d and the mean day temperature was higher 0.9°C than that in 2012,whereas the plant yield decreased by 2.5,8.5 and 10.9%,the net photosynthetic rate reduced by 7.5,10.5 and 18.0%,the RWC reduced by 3.9,5.6 and6.2%,and the WUE at leaf level reduced by 1.8,5.2 and 13.1%in the SS,R and RT treatments,respectively.Both the root length density and the soil moisture also decreased at different levels.The yield,photosynthetic rate,plant water status,root length density,and soil moisture under the SS and R treatments declined less than that under the RT treatment.The results indicated that SS and R can enhance the HTS resistance of spring maize during the filling stage,and led to higher yield by directly improving soil moisture and root growth and indirectly improving plant water status,photosynthesis and grain filling.The study can provide a theoretical basis for improving yield of maize by adjusting soil tillage in the NCP.展开更多
Plastic film mulch systems are used widely in arid areas, and the associated tillage measures affect soil properties, root and crop growth, and nutrient uptake. However, much debate surrounds the most suitable tillage...Plastic film mulch systems are used widely in arid areas, and the associated tillage measures affect soil properties, root and crop growth, and nutrient uptake. However, much debate surrounds the most suitable tillage method for plastic film mulch systems. We conducted a two-year field experiment to explore the impact of three tillage treatments-rotary tillage before ridge–furrow plastic film mulch(MR), no-tillage before ridge–furrow plastic film mulch(MZ), and plow tillage before ridge–furrow plastic film mulch(MP)-on soil total nitrogen, available nitrogen, root stratification structure,nitrogen transfer and utilization, and maize yield. The results showed that MP had better soil quality than either MR or MZ over 2019 and 2020, with higher nitrate-nitrogen and total nitrogen in the 0–40 cm soil layer. MP improved the soil physicochemical properties more than the other treatments, producing significantly higher root numbers and root biomass for the aerial and underground nodal roots than MR and MZ. At harvest, MP had the highest root biomass density,root length density, and root surface area density in the different soil layers(0–20, 20–40, and 0–40 cm). Significant correlations occurred between root biomass and aboveground nitrogen accumulation during maize growth. During grain filling, MP had the greatest nitrogen transfer amount, significantly increasing root and aboveground nitrogen transfer by 19.63–45.82% and 11.15–24.56%, respectively, relative to the other treatments. MP significantly produced 1.36–26.73%higher grain yields and a higher grain crude protein content at harvest than MR and MZ. MP also had higher values for the nitrogen harvest index, nitrogen uptake efficiency, and partial factor productivity of nitrogen fertilizer than MR and MZ.In conclusion, plow tillage combined with a ridge–furrow plastic film mulch system facilitated maize root development and improved nitrogen utilization, thereby increasing maize yield more than the other treatments.展开更多
In 2018 and 2021,the Drift-Towing Ocean Profilers(DTOP)provided extensive temperature and salinity data on the upper 120m ocean through their drifts over the Alpha Ridge north of the Canada Basin.The thickness and tem...In 2018 and 2021,the Drift-Towing Ocean Profilers(DTOP)provided extensive temperature and salinity data on the upper 120m ocean through their drifts over the Alpha Ridge north of the Canada Basin.The thickness and temperature maximum of Alaska Coastal Water(ACW)ranged from 20m to 40m and-1.5℃to-0.8℃,respectively,and the salinity generally maintained from 30.2 to 32.5.Comparison with World Ocean Atlas 2018’s climatology manifested a 40m-thick and warm ACW roughly ex-ceeding the temperature maximum by 0.4–0.5℃in June–August 2021.This anomalously warm ACW was highly related to the ex-pansion of the Beaufort Gyre in the negative Arctic Oscillation phase.During summer,the under-ice oceanic heat flux F_(w)^(OHF)was elevated,with a maximum value of above 25Wm^(-2).F_(w)^(OHF)was typically low in the freezing season,with an average value of 1.2Wm^(-2).The estimates of upward heat flux contributed by ACW to the sea ice bottom F_(w)^(OHF)were in the range of 3–4Wm^(-2)in June–August 2021,when ACW contained a heat content of more than 80MJm^(-2).The heat loss over this period was driven by a weak stratification upon the ACW layer associated with a surface mixed layer(SML)approaching the ACW core.After autumn,F_(w)^(OHF)was reduced(<2 Wm^(-2))except during rare events when it elevated F_(w)^(OHF)slightly.In addition,the intensive and widespread Ekman suction,which created a violent upwelling north of the Canada Basin,was largely responsible for the substantial cooling and thinning of the ACW layer in the summer of 2021.展开更多
The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models.These are:(i)the isospin-dependent A^(...The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models.These are:(i)the isospin-dependent A^(1∕3) formula,(ii)relativistic continuum Hartree-Bogoliubov(RCHB)theory,(iii)Hartree-Fock-Bogoliubov(HFB)model HFB25,(iv)the Weizsacker-Skyrme(WS)model WS*,and(v)HFB25*model.In the last two models,the charge radii were calculated using a five-parameter formula with the nuclear shell corrections and deformations obtained from the WS and HFB25 models,respectively.For each model,the resultant root-mean-square deviation for the 1014 nuclei with proton number Z≥8 can be significantly reduced to 0.009-0.013 fm after considering the modification with the EKRR method.The best among them was the RCHB model,with a root-mean-square deviation of 0.0092 fm.The extrapolation abilities of the KRR and EKRR methods for the neutron-rich region were examined,and it was found that after considering the odd-even effects,the extrapolation power was improved compared with that of the original KRR method.The strong odd-even staggering of nuclear charge radii of Ca and Cu isotopes and the abrupt kinks across the neutron N=126 and 82 shell closures were also calculated and could be reproduced quite well by calculations using the EKRR method.展开更多
Tillage practices during the fallow period benefit water storage and yield in dryland wheat crops.However,there is currently no clarity on the responses of soil organic carbon(SOC),total nitrogen(TN),and available nut...Tillage practices during the fallow period benefit water storage and yield in dryland wheat crops.However,there is currently no clarity on the responses of soil organic carbon(SOC),total nitrogen(TN),and available nutrients to tillage practices within the growing season.This study evaluated the effects of three tillage practices(NT,no tillage;SS,subsoil tillage;DT,deep tillage)over five years on soil physicochemical properties.Soil samples at harvest stage from the fifth year were analyzed to determine the soil aggregate and aggregate-associated C and N fractions.The results indicated that SS and DT improved grain yield,straw biomass and straw carbon return of wheat compared with NT.In contrast to DT and NT,SS favored SOC and TN concentrations and stocks by increasing the soil organic carbon sequestration rate(SOCSR)and soil nitrogen sequestration rate(TNSR)in the 0-40 cm layer.Higher SOC levels under SS and NT were associated with greater aggregate-associated C fractions,while TN was positively associated with soluble organic nitrogen(SON).Compared with DT,the NT and SS treatments improved soil available nutrients in the 0-20 cm layer.These findings suggest that SS is an excellent practice for increasing soil carbon,nitrogen and nutrient availability in dryland wheat fields in North China.展开更多
Biaxia lrotary tillage in dryland(DBRT)can complete biaxial rotary tillage with straw incorporation,secondary suppression,and ditching,and it has been previously studied in direct-seeded rice and wheat.However,the eff...Biaxia lrotary tillage in dryland(DBRT)can complete biaxial rotary tillage with straw incorporation,secondary suppression,and ditching,and it has been previously studied in direct-seeded rice and wheat.However,the effects of DBRT on the mechanically transplanted rice yield and greenhouse gas emissions remain unclear.To evaluate the effects of DBRT on improving the food security of mechanically transplanted rice and reducing the greenhouse gas emissions,we conducted an experiment for two years with wheat straw incorporation.Three tillage methods were set up:DBRT,uniaxial rotary tillage in dryland and paddy(DPURT),and uniaxial rotary tillage in paddy(PURT).The results showed that compared with DPURT and PURT,DBRT increased the yield of machine-transplanted rice by 7.5-11.0%and 13.3-26.7%,respectively,while the seasonal cumulative CH_(4) emissions were reduced by 13.9-21.2%and 30.2-37.0%,respectively,and the seasonal cumulative N_(2)O emissions were increased by 13.5-28.6%and 50.0-73.1%,respectively.Consequently,DBRT reduced the global warming potential by 10.7-15.5%and 23.7-28.6%,respectively,andtheyield-scaledglobalwarmingpotentialby18.2-21.8%and36.4-39.3%,respectively,compared to DPURT and PURT.These results were mainly related to the fact that DBRT significantly reduced soil bulk density and increased soil redox potential(Eh).Therefore,implementing DBRT in machine-transplanted rice fields is feasible,which cannot only increase the rice yield,but also reduce the greenhouse gas emissions.展开更多
Ground penetrating radar (GPR) surveys have being applied to investigate very near-surface stratification of sedimentary units in coastal plains and to define their depositional conditions. This paper presents, howeve...Ground penetrating radar (GPR) surveys have being applied to investigate very near-surface stratification of sedimentary units in coastal plains and to define their depositional conditions. This paper presents, however, low-frequency GPR survey to investigate fault-related depositional systems at greater depths. The Quinta-Cassino area in the Rio Grande do Sul Coastal Plain (RGSCP, Brazil) shows a wide strandplain that is made off by very long, continuous, and linear geomorphic features (beach ridges). This strandplain extends for ~70 km southward. The beach ridges show low-angle truncations against the Quinta escarpment, and also truncations in the strandplain. The traditional approach points that RGSCP was developed by juxtaposition of four lagoons/barrier systems as consequence of sea level changes;previous model assumes that no deformational episode occurred in RGSCP. The geophysical and geological surveys carried out in this area showed the existence of listric fault controlling the beach ridges in the escarpments and hanging-wall blocks. The radargrams could distinguish Pleistocene basement unit anticlockwise rotation, thickening of beach ridges radarfacies close to listric normal faults, and horst structures. These deformational features indicate that the extensional zone of a large-scale gravity-driven structure controlled the mechanical subsidence, the Holocene sedimentation and its stratigraphic and geomorphic features in the Quinta-Cassino area to build up an asymmetric delta. The results point to a new approach in dealing with RGSCP Holocene evolution.展开更多
No tillage(NT)and spring ridge tillage(SRT)are two common applications of conservation tillage.Although conservation tillage is known to exert major control over soil microbial respiration(SMR),the growing-season SMR ...No tillage(NT)and spring ridge tillage(SRT)are two common applications of conservation tillage.Although conservation tillage is known to exert major control over soil microbial respiration(SMR),the growing-season SMR response to these two applications remains elusive.In order to better understand the influence of conservation tillage practices,this experiment was conducted in an experimental field using NT and SRT for 17 years.In situ measurements of SMR,soil temperature and soil water content(SWC)were performed.Soil samples were collected to analyze soil porosity,soil microbial biomass(SMB)and soil enzymatic activities.Results show that the two conservation tillage systems had a significant difference(p<0.05)in terms of SMR;the SMR of NT was 14.7 mg∙C/m^(2)∙h higher than that of SRT.In terms of soil temperature and soil enzymatic activities,the two treatments were not significantly different(p>0.05).Despite SRT increasing the proportion of micro-porosities and meso-porosities,the soil macro-porosities for NT were 7.37%higher than that of SRT,which resulted in higher bacteria and fungi in NT.Owing to SRT damaged the hypha,which had disadvantage in soil microbe protection.Inversely,less soil disturbance was a unique advantage in NT,which was in favor of improving soil macro-pores and SWC.Redundancy analyses(RDA)showed SMR was positively correlated with soil macro-pores,SMB and SWC.Furthermore,the Pearson correlation test indicated that SMB and soil enzymatic activities did not have a significant correlation(p>0.05).This study results suggest that SRT is more conducive to carbon sequestration compared with NT in cropland.展开更多
A tillage method of combining ridge with no-tillage (RNT) was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern, soil water stable aggregate distribution, nut...A tillage method of combining ridge with no-tillage (RNT) was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern, soil water stable aggregate distribution, nutrients stratification and yields of rice and post-rice crops. After flooded paddy field (FPF) was practiced with RNT for a long time, soil profile changed from G to A-P-G, and horizon G was shifted to a deeper position in the profile. Also the proportion of macroaggregate (> 2 mm) increased, whereas the proportion of silt and clay (< 0.053 mm) decreased under RNT, indicating a better soil structure that will prevent erosion. RNT helped to control leaching and significantly improved total N, P, K and organic matter in soil. The highest crop yields were found under RNT system every year, and total crop yields were higher under conventional paddy-upland rotation tillage (CR) than under FPF, except in 2003 and 2006 when serious drought occurred. RNT was proven to be a better tillage method for lowland rice-based cropping system.展开更多
The fully mulched ridge–furrow(FMRF) system has been widely used on the semi-arid Loess Plateau of China due to its high maize(Zea mays L.) productivity and rainfall use efficiency. However, high outputs under this s...The fully mulched ridge–furrow(FMRF) system has been widely used on the semi-arid Loess Plateau of China due to its high maize(Zea mays L.) productivity and rainfall use efficiency. However, high outputs under this system led to a depletion of soil moisture and soil nutrients, which reduces its sustainability in the long run. Therefore, it is necessary to optimize the system for the sustainable development of agriculture. The development, yield-increasing mechanisms,negative impacts, optimization, and their relations in the FMRF system are reviewed in this paper. We suggest using grain and forage maize varieties instead of regular maize;mulching plastic film in autumn or leaving the mulch after maize harvesting until the next spring, and then removing the old film and mulching new film;combining reduced/notillage with straw return;utilizing crop rotation or intercropping with winter canola(Brassica campestris L.), millet(Setaria italica), or oilseed flax(Linum usitatissimum L.);reducing nitrogen fertilizer and partially replacing chemical fertilizer with organic fertilizer;using biodegradable or weather-resistant film;and implementing mechanized production. These integrations help to establish an environmentally friendly, high quality, and sustainable agricultural system, promote highquality development of dryland farming, and create new opportunities for agricultural development in the semi-arid Loess Plateau.展开更多
Submarine canyon-channel systems have been documented in the Parece Vela Basin,West Mariana Ridge;however,the mechanism of the formation and controlling factors remain poorly understood.Based on high-resolution multib...Submarine canyon-channel systems have been documented in the Parece Vela Basin,West Mariana Ridge;however,the mechanism of the formation and controlling factors remain poorly understood.Based on high-resolution multibeam bathymetric data and two-dimensional(2D)seismic profiles,we identified and mapped the submarine canyon-channel system along the middle segment of West Mariana Ridge in the Philippine Sea.These submarine canyon-channels show a main W-E orientation at depth of 2000–4500 m.They are approximately 72–128 km in length and 1.3–15 km in width,and their canyon heads are adjacent to the seamounts with several branches.The upper reaches of submarine canyon-channels are characterized by deeply incised,narrow,V-shaped thalwegs,suggesting the powerful erosion of gravity flows.The distinguished sediment waves are suggested to be resulted from the interaction of turbidity currents and seafloor.Our observations demonstrate that gravity flows originated from the collapses of seamount flanks plays a vital role in developing the submarine canyonchannel system along the West Mariana Ridge.This work provides better understanding of erosion,transport,and deposition of sediments from subducting ridges to deep-water basins,and also new insights into the origin and evolution of submarine canyon-channel systems along subducting ridges.展开更多
Straw is widely incorporated into soil worldwide,but most studies have concentrated on the effects of straw mulching or incorporation with topsoil.To determine the effect of depth of straw incorporation on bacterial a...Straw is widely incorporated into soil worldwide,but most studies have concentrated on the effects of straw mulching or incorporation with topsoil.To determine the effect of depth of straw incorporation on bacterial and fungal communities,we established a field experiment in a region in Northeast China with Haplic Chernozems using four treatments:conventional tillage(CT,tillage to a depth of 15 cm with no straw incorporation),straw incorporation with conventional tillage(SCT,tillage to a depth of 15 cm),inversion tillage(IT,tillage to a depth of 35 cm)and straw incorporation with inversion tillage(SIT,tillage to a depth of 35 cm).The soils were managed by inversion to a depth of 15 or 35 cm after harvest.The results show that soil organic carbon content was significantly higher and pH and bulk density were significantly lower in the 15–35 cm layer in IT and SIT than CT and SCT.Fungal abundance was higher with straw incorporation,but fungal diversity was lower in the 0–15 cm layer in SCT and SIT than in CT and IT.Path length in the bacterial network was shorter and connectivity was higher in CT+SCT than in IT+SIT,leading to a more complex ecosystem,and the fungal network had opposite patterns.The key taxa in the phylum Actinobacteriota and Ascomycota in the microbial networks changed dramatically at the genus level following inversion tillage with straw amendment,which may increase bacterial network resistance to environmental disturbances and unstable fungal networks,resulting in large changes in the fungal community involved in the decomposition of recalcitrant straw-derived C and the more efficient acquisition of limiting resources.展开更多
The Mohn Ridge separates the Greenland Sea and the Lofoten Basin.Previous studies identified the export across the Mohn Ridge(EMR)from the Greenland Basin into the Lofoten Basin using water mass analysis and the trace...The Mohn Ridge separates the Greenland Sea and the Lofoten Basin.Previous studies identified the export across the Mohn Ridge(EMR)from the Greenland Basin into the Lofoten Basin using water mass analysis and the tracer diffusion method,but there is still lack of direct current measurements.A surface mooring with four current meters was deployed on the Mohn Ridge from June 5 to June 18 in 2015,when three cyclones passed in the adjacent area.In the absence of cyclones,the flow on the Mohn Ridge was northeastward,parallel to the ridge.When cyclones appeared,the EMR occurred to transport Greenland Sea water into the Lofoten Basin.The probable mechanism is the sea level height variation caused by the perturbation of the low pressure of cyclones,which yields an outward pressure gradient force to drive the outflow.Our results suggest that the outflow is intermittent and only happens during cyclone activities.The annual mean volume flux of EMR was roughly estimated by the limited data,which is about 3.8×10^(6)m^(3)/s,a little bit smaller than the estimation based on volume conservation.The results indicate that the contribution of the cyclonic storms to EMR is a greatly important mechanism that potentially influences the global thermohaline circulation through the Greenland-Scotland Ridge overflow.展开更多
Extreme rainfall events on a slope under ridge tillage systems cause concentrated stream soil loss.To analyse the critical thresholds for different stages of water erosion process of ridge systems,simulated rainfall-e...Extreme rainfall events on a slope under ridge tillage systems cause concentrated stream soil loss.To analyse the critical thresholds for different stages of water erosion process of ridge systems,simulated rainfall-erosion experiments for the contour wide ridge(CWR),contour narrow ridge(CNR),longitudinal wide ridge(LWR),and longitudinal narrow ridge(LNR)were conducted under four rainfall intensities,with slope gradients of 3°and 5°.For the runoff event,the runoff depth order was LNR>LWR>CWR>CNR;the soil loss order was CNR>LNR>CWR>LWR.The product of slope factor(S)and rainfall erosivity(R)or runoff depth(D),can be adopted as critical thresholds for different stages of runoff and soil erosion process.For the longitudinal ridge systems,R values were provided for LWR and LNR and were the beginning of sheet flow,whereas the product of rainfall erosivity and slope factor(RS)values were provided for LWR and LNR as the beginning of the accelerated concentrated flow.For the contour ridge systems,R values were provided for CWR and CNR as critical thresholds for the beginning of overflow.The product of runoff depth and slope factor(DS)values were 9.98 and 7.73 mm for CWR and CNR,respectively,and were critical thresholds for the beginning of ridge failure;the DS values were 18.45 and 12.75 mm for CWR and CNR,respectively,and were critical thresholds for the beginning of the formation of ephemeral gully erosion.The critical thresholds can distinguish different stages of soil erosion process modelling.展开更多
The Tianxiu hydrothermal field(TXHF) located on Carlsberg Ridge is one of the few active ultramafic-hosted venting systems known in the Indian Ocean. Despite numerous investigations, there is limited understanding of ...The Tianxiu hydrothermal field(TXHF) located on Carlsberg Ridge is one of the few active ultramafic-hosted venting systems known in the Indian Ocean. Despite numerous investigations, there is limited understanding of its sulfide structure morphology, and the factors controlling the formation of TXHF are poorly understood. In this study, we conducted detailed seafloor mapping using visual data obtained by dives using the human-occupied vehicle(HOV) Jiaolong. The TXHF is found to be an active, off-axis, ultramafic-hosted, high-temperature hydrothermal area in which serpentine peridotite is exposed. Two main hydrothermal sites were identified, i.e., P and Y, both of which feature a complex of chimneys and beehive diffusers constituting a “chimney jungle” and isolated large steep-sided structures developed on flat-lying sulfide mounds. In addition, some sporadic inactive chimneys and outcrops of hydrothermal deposits were noted. The chimneys are rich in Fe and Zn sulfide, and lack the central fluid channel formed by focused high-temperature fluid flow. Hydrothermal venting at TXHF is likely related to low-angle detachment faults that focus and transport hydrothermal fluids away from a heat source along the valley wall. Our results complement and expand upon previous works concerning sulfide chimney morphology and their corresponding mineral paragenesis in ultramafic-hosted hydrothermal systems in the Indian Ocean and further our understanding of modern seafloor hydrothermal systems.展开更多
In view of the difficulty in calculating the atomic structure parameters of high-Z elements,the Hartree–Fock with relativistic corrections(HFR)theory in combination with the ridge regression(RR)algorithm rather than ...In view of the difficulty in calculating the atomic structure parameters of high-Z elements,the Hartree–Fock with relativistic corrections(HFR)theory in combination with the ridge regression(RR)algorithm rather than the Cowan code’s least squares fitting(LSF)method is proposed and applied.By analyzing the energy level structure parameters of the HFR theory and using the fitting experimental energy level extrapolation method,some excited state energy levels of the Yb I(Z=70)atom including the 4f open shell are calculated.The advantages of the ridge regression algorithm are demonstrated by comparing it with Cowan code’s LSF results.In addition,the results obtained by the new method are compared with the experimental results and other theoretical results to demonstrate the reliability and accuracy of our approach.展开更多
The estimation of ship speed in ice ridge fields is important for both route planning and prediction of emergency response time.An analytical method for estimating ship motion in first-year ice ridge is developed base...The estimation of ship speed in ice ridge fields is important for both route planning and prediction of emergency response time.An analytical method for estimating ship motion in first-year ice ridge is developed based on ice resistance models and ship motion equations,in which the effect of ship speed on ridge resistance is taken into account.Two model tests in level ice and one model test in ice ridge for an icebreaking multipurpose vessel are used to validate and benchmark the presented method.The predicted results including level ice resistances,net thrust and ship motion in the ice ridge field are compared with the model test data.The comparisons show that the presented method can generate reasonable results.The effects of input parameters on ship speed,penetration depth and number of necessary rams to transit ridge have been studied.Based on the calibrated model,insights into the ice resistance and the ship motion are obtained.It is found that the energy consumption of the keel obtained by integral calculation of the keel resistance at the penetration distance is with the same magnitude as the result of the maximum keel resistance multiplied by the ridge length.In addition,the effect of ridge width and keel depth on keel resistance and average transit speed is investigated.展开更多
Wrinkle ridges are common landforms documented on all rocky planets and the Moon in the inner solar system.Despite the long research history,their formation mechanisms remain debated.A key unresolved issue is whether ...Wrinkle ridges are common landforms documented on all rocky planets and the Moon in the inner solar system.Despite the long research history,their formation mechanisms remain debated.A key unresolved issue is whether the wrinkle-ridge formation is related to igneous processes.This is because wrinkle ridges are mostly associated in space and possibly in time with the occurrence of flood-basalt volcanism in all cases in the inner solar system.To address this issue,we conducted geomorphological mapping,a topographic-data analysis,and a detailed landform and landsystem analysis of satellite images at a resolution of 25 cm/pixel to 6 m/pixel in the central Tharsis region of Mars.The main results of this work are in the form of(1)a regional geomorphological map at a resolution of 6 m/pixel and(2)a local geomorphological map at a resolution of 50 cm/pixel.Our work suggests the following older-to-younger sequence of geological events in the study area:(1)formation of a northeast-trending mountain range(i.e.,the Thaumasia plateau)along the eastern margin of the Tharsis rise that was created by the Himalayan-style crustal-scale thrusting;(2)coeval volcanic-plateau construction west of the thrusting-induced rising mountain range;(3)eastward-flowing lavas that were sourced from a volcanic plateau to the west terminated at the rising Thaumasia plateau to the east;(4)wrinkle-ridge development by decollement folding of recently emplaced warm,ductile volcanic-lava piles;(5)emplacement of a regionally extensive ice sheet over the central Tharsis region that produced extensive boulder-bearing materials,striated surfaces,and boulder-bearing dendritic-ridge networks possibly representing subglacial eskers;and(6)local deposition of highly concentrated glacial flours resulted in the formation of mantled terrain on plains between wrinkle ridges.Our work supports the early suggestion that the Tharsis wrinkle ridges were created by horizontal shortening induced by crustal-scale tectonic processes.In detail,however,the occurrence of flow-front-like fold margins associated with many mapped wrinkle ridges suggests the involvement of ductile-flow deformation during ridge formation.We attribute the flow-like fold fronts to ductile deformation of thermally weakened lava piles that were emplaced during or immediately before the folding event.Our compression-induced wrinkle-ridge model also differs from the early hypotheses in that the thin-skinned folding is associated with basement subduction,which explains the lack of coeval and parallel folding and extensional faulting associated with wrinkle ridge formation in the study area.Post-folding glacial modification means that the present wrinkle-ridge morphologies may differ significantly from the original fold shapes,which prevents the utility of using topographic profiles across wrinkle ridges for inverting the underlying thrust geometries.展开更多
Short Retraction Notice The paper does not meet the standards of "Advances in Bioscience and Biotechnology". This article has been retracted to straighten the academic record. In making this decision the Edi...Short Retraction Notice The paper does not meet the standards of "Advances in Bioscience and Biotechnology". This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. The aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused. Editor guiding this retraction: Prof. Abass Alavi (EiC of ABB). Please see the article page for more details. The full retraction notice in PDF is preceding the original paper which is marked "RETRACTED".展开更多
基金supported by the National Key Technologies R&D Program of China during the 12th Five-Year Plan period(2011BAD16B15)
文摘High temperature stress(HTS)on spring maize(Zea mays L.)during the filling stage is the key factor that limits the yield increase in the North China Plain(NCP).Subsoiling(SS)and ridge tillage(R)were introduced to enhance the ability of spring maize to resist HTS during the filling stage.The field experiments were conducted during the 2011 and 2012 maize growing seasons at Wuqiao County,Hebei Province,China.Compared with rotary tillage(RT),the net photosynthetic rate,stomatal conductance,transpiration rate,and chlorophyll relative content(SPAD)of maize leaves was increased by 40.0,42.6,12.8,and 29.7%under SS,and increased by 20.4,20.0,5.4,and 14.2%under R,repectively.However,the treatments reduce the intercellular CO2concentration under HTS.The SS and R treatments increased the relative water content(RWC)by 11.9 and6.2%,and the water use efficiency(WUE)by 24.3 and 14.3%,respectively,compared with RT.The SS treatment increased the root length density and soil moisture in the 0-80 cm soil profile,whereas the R treatment increased the root length density and soil moisture in the 0-40 cm soil profile compared with the RT treatment.Compared with 2011,the number of days with temperatures 33°C was more 2 d and the mean day temperature was higher 0.9°C than that in 2012,whereas the plant yield decreased by 2.5,8.5 and 10.9%,the net photosynthetic rate reduced by 7.5,10.5 and 18.0%,the RWC reduced by 3.9,5.6 and6.2%,and the WUE at leaf level reduced by 1.8,5.2 and 13.1%in the SS,R and RT treatments,respectively.Both the root length density and the soil moisture also decreased at different levels.The yield,photosynthetic rate,plant water status,root length density,and soil moisture under the SS and R treatments declined less than that under the RT treatment.The results indicated that SS and R can enhance the HTS resistance of spring maize during the filling stage,and led to higher yield by directly improving soil moisture and root growth and indirectly improving plant water status,photosynthesis and grain filling.The study can provide a theoretical basis for improving yield of maize by adjusting soil tillage in the NCP.
基金provided by the National Natural Science Foundation of China (31701384 and 32071980)。
文摘Plastic film mulch systems are used widely in arid areas, and the associated tillage measures affect soil properties, root and crop growth, and nutrient uptake. However, much debate surrounds the most suitable tillage method for plastic film mulch systems. We conducted a two-year field experiment to explore the impact of three tillage treatments-rotary tillage before ridge–furrow plastic film mulch(MR), no-tillage before ridge–furrow plastic film mulch(MZ), and plow tillage before ridge–furrow plastic film mulch(MP)-on soil total nitrogen, available nitrogen, root stratification structure,nitrogen transfer and utilization, and maize yield. The results showed that MP had better soil quality than either MR or MZ over 2019 and 2020, with higher nitrate-nitrogen and total nitrogen in the 0–40 cm soil layer. MP improved the soil physicochemical properties more than the other treatments, producing significantly higher root numbers and root biomass for the aerial and underground nodal roots than MR and MZ. At harvest, MP had the highest root biomass density,root length density, and root surface area density in the different soil layers(0–20, 20–40, and 0–40 cm). Significant correlations occurred between root biomass and aboveground nitrogen accumulation during maize growth. During grain filling, MP had the greatest nitrogen transfer amount, significantly increasing root and aboveground nitrogen transfer by 19.63–45.82% and 11.15–24.56%, respectively, relative to the other treatments. MP significantly produced 1.36–26.73%higher grain yields and a higher grain crude protein content at harvest than MR and MZ. MP also had higher values for the nitrogen harvest index, nitrogen uptake efficiency, and partial factor productivity of nitrogen fertilizer than MR and MZ.In conclusion, plow tillage combined with a ridge–furrow plastic film mulch system facilitated maize root development and improved nitrogen utilization, thereby increasing maize yield more than the other treatments.
基金supported by the National Natural Science Foundation of China(Nos.42276239 and 41941012)the National Key R&D Program of China(No.2019YFC1509101)the Fundamental Research Funds for the Central Universities(No.202165005).
文摘In 2018 and 2021,the Drift-Towing Ocean Profilers(DTOP)provided extensive temperature and salinity data on the upper 120m ocean through their drifts over the Alpha Ridge north of the Canada Basin.The thickness and temperature maximum of Alaska Coastal Water(ACW)ranged from 20m to 40m and-1.5℃to-0.8℃,respectively,and the salinity generally maintained from 30.2 to 32.5.Comparison with World Ocean Atlas 2018’s climatology manifested a 40m-thick and warm ACW roughly ex-ceeding the temperature maximum by 0.4–0.5℃in June–August 2021.This anomalously warm ACW was highly related to the ex-pansion of the Beaufort Gyre in the negative Arctic Oscillation phase.During summer,the under-ice oceanic heat flux F_(w)^(OHF)was elevated,with a maximum value of above 25Wm^(-2).F_(w)^(OHF)was typically low in the freezing season,with an average value of 1.2Wm^(-2).The estimates of upward heat flux contributed by ACW to the sea ice bottom F_(w)^(OHF)were in the range of 3–4Wm^(-2)in June–August 2021,when ACW contained a heat content of more than 80MJm^(-2).The heat loss over this period was driven by a weak stratification upon the ACW layer associated with a surface mixed layer(SML)approaching the ACW core.After autumn,F_(w)^(OHF)was reduced(<2 Wm^(-2))except during rare events when it elevated F_(w)^(OHF)slightly.In addition,the intensive and widespread Ekman suction,which created a violent upwelling north of the Canada Basin,was largely responsible for the substantial cooling and thinning of the ACW layer in the summer of 2021.
基金This work was supported by the National Natural Science Foundation of China(Nos.11875027,11975096).
文摘The extended kernel ridge regression(EKRR)method with odd-even effects was adopted to improve the description of the nuclear charge radius using five commonly used nuclear models.These are:(i)the isospin-dependent A^(1∕3) formula,(ii)relativistic continuum Hartree-Bogoliubov(RCHB)theory,(iii)Hartree-Fock-Bogoliubov(HFB)model HFB25,(iv)the Weizsacker-Skyrme(WS)model WS*,and(v)HFB25*model.In the last two models,the charge radii were calculated using a five-parameter formula with the nuclear shell corrections and deformations obtained from the WS and HFB25 models,respectively.For each model,the resultant root-mean-square deviation for the 1014 nuclei with proton number Z≥8 can be significantly reduced to 0.009-0.013 fm after considering the modification with the EKRR method.The best among them was the RCHB model,with a root-mean-square deviation of 0.0092 fm.The extrapolation abilities of the KRR and EKRR methods for the neutron-rich region were examined,and it was found that after considering the odd-even effects,the extrapolation power was improved compared with that of the original KRR method.The strong odd-even staggering of nuclear charge radii of Ca and Cu isotopes and the abrupt kinks across the neutron N=126 and 82 shell closures were also calculated and could be reproduced quite well by calculations using the EKRR method.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(U22A20609)the National Key Research and Development Program of China(2021YFD1901102-4)+2 种基金the State Key Laboratory of Integrative Sustainable Dryland Agriculture(in preparation)the Shanxi Agricultural University,China(202003-3)the Open Fund from the State Key Laboratory of Soil Environment and Nutrient Resources of Shanxi Province,China(2020002)。
文摘Tillage practices during the fallow period benefit water storage and yield in dryland wheat crops.However,there is currently no clarity on the responses of soil organic carbon(SOC),total nitrogen(TN),and available nutrients to tillage practices within the growing season.This study evaluated the effects of three tillage practices(NT,no tillage;SS,subsoil tillage;DT,deep tillage)over five years on soil physicochemical properties.Soil samples at harvest stage from the fifth year were analyzed to determine the soil aggregate and aggregate-associated C and N fractions.The results indicated that SS and DT improved grain yield,straw biomass and straw carbon return of wheat compared with NT.In contrast to DT and NT,SS favored SOC and TN concentrations and stocks by increasing the soil organic carbon sequestration rate(SOCSR)and soil nitrogen sequestration rate(TNSR)in the 0-40 cm layer.Higher SOC levels under SS and NT were associated with greater aggregate-associated C fractions,while TN was positively associated with soluble organic nitrogen(SON).Compared with DT,the NT and SS treatments improved soil available nutrients in the 0-20 cm layer.These findings suggest that SS is an excellent practice for increasing soil carbon,nitrogen and nutrient availability in dryland wheat fields in North China.
基金jointly supported by the Key R&D Program of Jiangsu ProvinceChina(BE2022338)+3 种基金the Jiangsu Agriculture Science and Technology Innovation FundChina(CX(20)1012)the National Natural Science Foundation of China(31801293)a project funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China。
文摘Biaxia lrotary tillage in dryland(DBRT)can complete biaxial rotary tillage with straw incorporation,secondary suppression,and ditching,and it has been previously studied in direct-seeded rice and wheat.However,the effects of DBRT on the mechanically transplanted rice yield and greenhouse gas emissions remain unclear.To evaluate the effects of DBRT on improving the food security of mechanically transplanted rice and reducing the greenhouse gas emissions,we conducted an experiment for two years with wheat straw incorporation.Three tillage methods were set up:DBRT,uniaxial rotary tillage in dryland and paddy(DPURT),and uniaxial rotary tillage in paddy(PURT).The results showed that compared with DPURT and PURT,DBRT increased the yield of machine-transplanted rice by 7.5-11.0%and 13.3-26.7%,respectively,while the seasonal cumulative CH_(4) emissions were reduced by 13.9-21.2%and 30.2-37.0%,respectively,and the seasonal cumulative N_(2)O emissions were increased by 13.5-28.6%and 50.0-73.1%,respectively.Consequently,DBRT reduced the global warming potential by 10.7-15.5%and 23.7-28.6%,respectively,andtheyield-scaledglobalwarmingpotentialby18.2-21.8%and36.4-39.3%,respectively,compared to DPURT and PURT.These results were mainly related to the fact that DBRT significantly reduced soil bulk density and increased soil redox potential(Eh).Therefore,implementing DBRT in machine-transplanted rice fields is feasible,which cannot only increase the rice yield,but also reduce the greenhouse gas emissions.
文摘Ground penetrating radar (GPR) surveys have being applied to investigate very near-surface stratification of sedimentary units in coastal plains and to define their depositional conditions. This paper presents, however, low-frequency GPR survey to investigate fault-related depositional systems at greater depths. The Quinta-Cassino area in the Rio Grande do Sul Coastal Plain (RGSCP, Brazil) shows a wide strandplain that is made off by very long, continuous, and linear geomorphic features (beach ridges). This strandplain extends for ~70 km southward. The beach ridges show low-angle truncations against the Quinta escarpment, and also truncations in the strandplain. The traditional approach points that RGSCP was developed by juxtaposition of four lagoons/barrier systems as consequence of sea level changes;previous model assumes that no deformational episode occurred in RGSCP. The geophysical and geological surveys carried out in this area showed the existence of listric fault controlling the beach ridges in the escarpments and hanging-wall blocks. The radargrams could distinguish Pleistocene basement unit anticlockwise rotation, thickening of beach ridges radarfacies close to listric normal faults, and horst structures. These deformational features indicate that the extensional zone of a large-scale gravity-driven structure controlled the mechanical subsidence, the Holocene sedimentation and its stratigraphic and geomorphic features in the Quinta-Cassino area to build up an asymmetric delta. The results point to a new approach in dealing with RGSCP Holocene evolution.
基金This work was supported by the National Natural Science Foundation of China(31901408)as well as Science and Technology Development Plan of Jilin Province(20180414074GH)Special thanks to OeAD-Austrian Agency for International Cooperation in Education and Research.
文摘No tillage(NT)and spring ridge tillage(SRT)are two common applications of conservation tillage.Although conservation tillage is known to exert major control over soil microbial respiration(SMR),the growing-season SMR response to these two applications remains elusive.In order to better understand the influence of conservation tillage practices,this experiment was conducted in an experimental field using NT and SRT for 17 years.In situ measurements of SMR,soil temperature and soil water content(SWC)were performed.Soil samples were collected to analyze soil porosity,soil microbial biomass(SMB)and soil enzymatic activities.Results show that the two conservation tillage systems had a significant difference(p<0.05)in terms of SMR;the SMR of NT was 14.7 mg∙C/m^(2)∙h higher than that of SRT.In terms of soil temperature and soil enzymatic activities,the two treatments were not significantly different(p>0.05).Despite SRT increasing the proportion of micro-porosities and meso-porosities,the soil macro-porosities for NT were 7.37%higher than that of SRT,which resulted in higher bacteria and fungi in NT.Owing to SRT damaged the hypha,which had disadvantage in soil microbe protection.Inversely,less soil disturbance was a unique advantage in NT,which was in favor of improving soil macro-pores and SWC.Redundancy analyses(RDA)showed SMR was positively correlated with soil macro-pores,SMB and SWC.Furthermore,the Pearson correlation test indicated that SMB and soil enzymatic activities did not have a significant correlation(p>0.05).This study results suggest that SRT is more conducive to carbon sequestration compared with NT in cropland.
基金Project supported by the National Natural Science Foundation of China (No.40501033)the National Key Technologies R&D Program for the 11th Five-Year Plan of China (No.2007BAD87B10)
文摘A tillage method of combining ridge with no-tillage (RNT) was employed in lowland rice-based cropping system to study the long-term effects of RNT on soil profile pattern, soil water stable aggregate distribution, nutrients stratification and yields of rice and post-rice crops. After flooded paddy field (FPF) was practiced with RNT for a long time, soil profile changed from G to A-P-G, and horizon G was shifted to a deeper position in the profile. Also the proportion of macroaggregate (> 2 mm) increased, whereas the proportion of silt and clay (< 0.053 mm) decreased under RNT, indicating a better soil structure that will prevent erosion. RNT helped to control leaching and significantly improved total N, P, K and organic matter in soil. The highest crop yields were found under RNT system every year, and total crop yields were higher under conventional paddy-upland rotation tillage (CR) than under FPF, except in 2003 and 2006 when serious drought occurred. RNT was proven to be a better tillage method for lowland rice-based cropping system.
基金supported by the Major Special Research projects in Gansu Province, China (22ZD6NA009)the National Key R&D Program of China (2022YFD1900300)+4 种基金the State Key Laboratory of Aridland Crop Science, Gansu Agricultural University, China (GSCS-2022-Z02)the Fostering Foundation for the Excellent Ph.D. Dissertation of Gansu Agricultural University, China (YB2020002)the Innovation Star Project for Excellent Graduate Student of Department of Education of Gansu Province, China (2021CXZX-369)the Young Instructor Fund Project of Gansu Agricultural University, China (GAU-QDFC-2020-03)the Science and Technology Project of Gansu Province, China (20JR5RA033)。
文摘The fully mulched ridge–furrow(FMRF) system has been widely used on the semi-arid Loess Plateau of China due to its high maize(Zea mays L.) productivity and rainfall use efficiency. However, high outputs under this system led to a depletion of soil moisture and soil nutrients, which reduces its sustainability in the long run. Therefore, it is necessary to optimize the system for the sustainable development of agriculture. The development, yield-increasing mechanisms,negative impacts, optimization, and their relations in the FMRF system are reviewed in this paper. We suggest using grain and forage maize varieties instead of regular maize;mulching plastic film in autumn or leaving the mulch after maize harvesting until the next spring, and then removing the old film and mulching new film;combining reduced/notillage with straw return;utilizing crop rotation or intercropping with winter canola(Brassica campestris L.), millet(Setaria italica), or oilseed flax(Linum usitatissimum L.);reducing nitrogen fertilizer and partially replacing chemical fertilizer with organic fertilizer;using biodegradable or weather-resistant film;and implementing mechanized production. These integrations help to establish an environmentally friendly, high quality, and sustainable agricultural system, promote highquality development of dryland farming, and create new opportunities for agricultural development in the semi-arid Loess Plateau.
基金Supported by the National Natural Science Foundation of China(No.91958211)the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB42020000)+1 种基金the Laoshan Laboratory Project(No.LSKJ202203503)the Key Deployment Project of Center for Ocean Mega-Research of Science,Chinese Academy of Sciences(No.COMS2019Q10).Dr.Wei LI is funded by the CAS Pioneer Hundred-Talents Program。
文摘Submarine canyon-channel systems have been documented in the Parece Vela Basin,West Mariana Ridge;however,the mechanism of the formation and controlling factors remain poorly understood.Based on high-resolution multibeam bathymetric data and two-dimensional(2D)seismic profiles,we identified and mapped the submarine canyon-channel system along the middle segment of West Mariana Ridge in the Philippine Sea.These submarine canyon-channels show a main W-E orientation at depth of 2000–4500 m.They are approximately 72–128 km in length and 1.3–15 km in width,and their canyon heads are adjacent to the seamounts with several branches.The upper reaches of submarine canyon-channels are characterized by deeply incised,narrow,V-shaped thalwegs,suggesting the powerful erosion of gravity flows.The distinguished sediment waves are suggested to be resulted from the interaction of turbidity currents and seafloor.Our observations demonstrate that gravity flows originated from the collapses of seamount flanks plays a vital role in developing the submarine canyonchannel system along the West Mariana Ridge.This work provides better understanding of erosion,transport,and deposition of sediments from subducting ridges to deep-water basins,and also new insights into the origin and evolution of submarine canyon-channel systems along subducting ridges.
基金Under the auspices of Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA28070100)the National Key Research and Development Program of China(No.2022YFD1500100)+1 种基金the National Natural Science Foundation of China(No.41807085)the Earmarked Fund for China Agriculture Research System(No.CARS04)。
文摘Straw is widely incorporated into soil worldwide,but most studies have concentrated on the effects of straw mulching or incorporation with topsoil.To determine the effect of depth of straw incorporation on bacterial and fungal communities,we established a field experiment in a region in Northeast China with Haplic Chernozems using four treatments:conventional tillage(CT,tillage to a depth of 15 cm with no straw incorporation),straw incorporation with conventional tillage(SCT,tillage to a depth of 15 cm),inversion tillage(IT,tillage to a depth of 35 cm)and straw incorporation with inversion tillage(SIT,tillage to a depth of 35 cm).The soils were managed by inversion to a depth of 15 or 35 cm after harvest.The results show that soil organic carbon content was significantly higher and pH and bulk density were significantly lower in the 15–35 cm layer in IT and SIT than CT and SCT.Fungal abundance was higher with straw incorporation,but fungal diversity was lower in the 0–15 cm layer in SCT and SIT than in CT and IT.Path length in the bacterial network was shorter and connectivity was higher in CT+SCT than in IT+SIT,leading to a more complex ecosystem,and the fungal network had opposite patterns.The key taxa in the phylum Actinobacteriota and Ascomycota in the microbial networks changed dramatically at the genus level following inversion tillage with straw amendment,which may increase bacterial network resistance to environmental disturbances and unstable fungal networks,resulting in large changes in the fungal community involved in the decomposition of recalcitrant straw-derived C and the more efficient acquisition of limiting resources.
基金The Major Scientific and Technological Innovation Projects of Shandong Province under contract No.2018SDKJ0104-1the National Natural Science Foundation of China under contract Nos 41941012 and 41976022.
文摘The Mohn Ridge separates the Greenland Sea and the Lofoten Basin.Previous studies identified the export across the Mohn Ridge(EMR)from the Greenland Basin into the Lofoten Basin using water mass analysis and the tracer diffusion method,but there is still lack of direct current measurements.A surface mooring with four current meters was deployed on the Mohn Ridge from June 5 to June 18 in 2015,when three cyclones passed in the adjacent area.In the absence of cyclones,the flow on the Mohn Ridge was northeastward,parallel to the ridge.When cyclones appeared,the EMR occurred to transport Greenland Sea water into the Lofoten Basin.The probable mechanism is the sea level height variation caused by the perturbation of the low pressure of cyclones,which yields an outward pressure gradient force to drive the outflow.Our results suggest that the outflow is intermittent and only happens during cyclone activities.The annual mean volume flux of EMR was roughly estimated by the limited data,which is about 3.8×10^(6)m^(3)/s,a little bit smaller than the estimation based on volume conservation.The results indicate that the contribution of the cyclonic storms to EMR is a greatly important mechanism that potentially influences the global thermohaline circulation through the Greenland-Scotland Ridge overflow.
基金funded by the IWHR Research&Development Support Program(Grant SE0145B032021)the National Key Research and Development Program of China(Grant 2018YFC0507002)。
文摘Extreme rainfall events on a slope under ridge tillage systems cause concentrated stream soil loss.To analyse the critical thresholds for different stages of water erosion process of ridge systems,simulated rainfall-erosion experiments for the contour wide ridge(CWR),contour narrow ridge(CNR),longitudinal wide ridge(LWR),and longitudinal narrow ridge(LNR)were conducted under four rainfall intensities,with slope gradients of 3°and 5°.For the runoff event,the runoff depth order was LNR>LWR>CWR>CNR;the soil loss order was CNR>LNR>CWR>LWR.The product of slope factor(S)and rainfall erosivity(R)or runoff depth(D),can be adopted as critical thresholds for different stages of runoff and soil erosion process.For the longitudinal ridge systems,R values were provided for LWR and LNR and were the beginning of sheet flow,whereas the product of rainfall erosivity and slope factor(RS)values were provided for LWR and LNR as the beginning of the accelerated concentrated flow.For the contour ridge systems,R values were provided for CWR and CNR as critical thresholds for the beginning of overflow.The product of runoff depth and slope factor(DS)values were 9.98 and 7.73 mm for CWR and CNR,respectively,and were critical thresholds for the beginning of ridge failure;the DS values were 18.45 and 12.75 mm for CWR and CNR,respectively,and were critical thresholds for the beginning of the formation of ephemeral gully erosion.The critical thresholds can distinguish different stages of soil erosion process modelling.
基金The National Key Research and Development Program of China under contract No. 2017YFC0306603the National Key Research and Development Program of China under contract No. 2021YFC2801705+2 种基金the Scientific Research Fund of the Second Institute of OceanographyMinistry of Natural Resources under contract Nos JG1905 and SZ2201the National Natural Science Foundation of China under contract No. 41806076。
文摘The Tianxiu hydrothermal field(TXHF) located on Carlsberg Ridge is one of the few active ultramafic-hosted venting systems known in the Indian Ocean. Despite numerous investigations, there is limited understanding of its sulfide structure morphology, and the factors controlling the formation of TXHF are poorly understood. In this study, we conducted detailed seafloor mapping using visual data obtained by dives using the human-occupied vehicle(HOV) Jiaolong. The TXHF is found to be an active, off-axis, ultramafic-hosted, high-temperature hydrothermal area in which serpentine peridotite is exposed. Two main hydrothermal sites were identified, i.e., P and Y, both of which feature a complex of chimneys and beehive diffusers constituting a “chimney jungle” and isolated large steep-sided structures developed on flat-lying sulfide mounds. In addition, some sporadic inactive chimneys and outcrops of hydrothermal deposits were noted. The chimneys are rich in Fe and Zn sulfide, and lack the central fluid channel formed by focused high-temperature fluid flow. Hydrothermal venting at TXHF is likely related to low-angle detachment faults that focus and transport hydrothermal fluids away from a heat source along the valley wall. Our results complement and expand upon previous works concerning sulfide chimney morphology and their corresponding mineral paragenesis in ultramafic-hosted hydrothermal systems in the Indian Ocean and further our understanding of modern seafloor hydrothermal systems.
基金the Fundamental Research Funds for the Central Universities(Grant No.10822041A2038).
文摘In view of the difficulty in calculating the atomic structure parameters of high-Z elements,the Hartree–Fock with relativistic corrections(HFR)theory in combination with the ridge regression(RR)algorithm rather than the Cowan code’s least squares fitting(LSF)method is proposed and applied.By analyzing the energy level structure parameters of the HFR theory and using the fitting experimental energy level extrapolation method,some excited state energy levels of the Yb I(Z=70)atom including the 4f open shell are calculated.The advantages of the ridge regression algorithm are demonstrated by comparing it with Cowan code’s LSF results.In addition,the results obtained by the new method are compared with the experimental results and other theoretical results to demonstrate the reliability and accuracy of our approach.
基金financially supported by the Natural Science Foundation of Jiangsu Province of China (Grant No.BK20200998)the National Natural Science Foundation of China (Grant Nos.52171311,52271279,and 51579130)。
文摘The estimation of ship speed in ice ridge fields is important for both route planning and prediction of emergency response time.An analytical method for estimating ship motion in first-year ice ridge is developed based on ice resistance models and ship motion equations,in which the effect of ship speed on ridge resistance is taken into account.Two model tests in level ice and one model test in ice ridge for an icebreaking multipurpose vessel are used to validate and benchmark the presented method.The predicted results including level ice resistances,net thrust and ship motion in the ice ridge field are compared with the model test data.The comparisons show that the presented method can generate reasonable results.The effects of input parameters on ship speed,penetration depth and number of necessary rams to transit ridge have been studied.Based on the calibrated model,insights into the ice resistance and the ship motion are obtained.It is found that the energy consumption of the keel obtained by integral calculation of the keel resistance at the penetration distance is with the same magnitude as the result of the maximum keel resistance multiplied by the ridge length.In addition,the effect of ridge width and keel depth on keel resistance and average transit speed is investigated.
文摘Wrinkle ridges are common landforms documented on all rocky planets and the Moon in the inner solar system.Despite the long research history,their formation mechanisms remain debated.A key unresolved issue is whether the wrinkle-ridge formation is related to igneous processes.This is because wrinkle ridges are mostly associated in space and possibly in time with the occurrence of flood-basalt volcanism in all cases in the inner solar system.To address this issue,we conducted geomorphological mapping,a topographic-data analysis,and a detailed landform and landsystem analysis of satellite images at a resolution of 25 cm/pixel to 6 m/pixel in the central Tharsis region of Mars.The main results of this work are in the form of(1)a regional geomorphological map at a resolution of 6 m/pixel and(2)a local geomorphological map at a resolution of 50 cm/pixel.Our work suggests the following older-to-younger sequence of geological events in the study area:(1)formation of a northeast-trending mountain range(i.e.,the Thaumasia plateau)along the eastern margin of the Tharsis rise that was created by the Himalayan-style crustal-scale thrusting;(2)coeval volcanic-plateau construction west of the thrusting-induced rising mountain range;(3)eastward-flowing lavas that were sourced from a volcanic plateau to the west terminated at the rising Thaumasia plateau to the east;(4)wrinkle-ridge development by decollement folding of recently emplaced warm,ductile volcanic-lava piles;(5)emplacement of a regionally extensive ice sheet over the central Tharsis region that produced extensive boulder-bearing materials,striated surfaces,and boulder-bearing dendritic-ridge networks possibly representing subglacial eskers;and(6)local deposition of highly concentrated glacial flours resulted in the formation of mantled terrain on plains between wrinkle ridges.Our work supports the early suggestion that the Tharsis wrinkle ridges were created by horizontal shortening induced by crustal-scale tectonic processes.In detail,however,the occurrence of flow-front-like fold margins associated with many mapped wrinkle ridges suggests the involvement of ductile-flow deformation during ridge formation.We attribute the flow-like fold fronts to ductile deformation of thermally weakened lava piles that were emplaced during or immediately before the folding event.Our compression-induced wrinkle-ridge model also differs from the early hypotheses in that the thin-skinned folding is associated with basement subduction,which explains the lack of coeval and parallel folding and extensional faulting associated with wrinkle ridge formation in the study area.Post-folding glacial modification means that the present wrinkle-ridge morphologies may differ significantly from the original fold shapes,which prevents the utility of using topographic profiles across wrinkle ridges for inverting the underlying thrust geometries.
文摘Short Retraction Notice The paper does not meet the standards of "Advances in Bioscience and Biotechnology". This article has been retracted to straighten the academic record. In making this decision the Editorial Board follows COPE's Retraction Guidelines. The aim is to promote the circulation of scientific research by offering an ideal research publication platform with due consideration of internationally accepted standards on publication ethics. The Editorial Board would like to extend its sincere apologies for any inconvenience this retraction may have caused. Editor guiding this retraction: Prof. Abass Alavi (EiC of ABB). Please see the article page for more details. The full retraction notice in PDF is preceding the original paper which is marked "RETRACTED".
