This study compared the impact of three indirect heating systems to direct gas flame heaters on a selection of flock performance and environmental indicators in commercial broiler units. No statistically significant d...This study compared the impact of three indirect heating systems to direct gas flame heaters on a selection of flock performance and environmental indicators in commercial broiler units. No statistically significant differences（P≥0.05） were found in flock mortality rates, bird weight, water consumption, stress response, carbon dioxide, ammonia, temperature, relative humidity, litter quality, within-flock Campylobacter levels or mean Campylobacter counts when flock data from any of the three indirect heating systems were compared to flocks reared in houses with direct heating systems. Differences in litter quality were observed between upper and lower litter layers in all houses, regardless of heating type, which may have implications for bird health and welfare. Carbon dioxide concentrations in houses with direct heating systems were significantly higher than those in houses with indirect heating systems during the first 10 days of bird life（P≤0.05）. This was due to the increased use of heating systems during this period of the flock cycle. Differences in CO2 concentrations had no effect on flock performance, possibly due to the fact that concentrations did not exceed known safe levels. A statistically significant increase in stress response was observed in birds as a result of partial depopulation（thinning） within houses, irrespective of heating system type used（P≤0.05）. Stress associated with thinning may have consequences for bird welfare and food safety. In conclusion, the results of our study suggest that indirect heating systems do not appear to negatively impact on flock performance, stress response, within-flock Campylobacter levels or mean Campylobacter counts and do not appear to significantly alter environmental conditions within broiler houses when compared to houses equipped with direct heating systems. Indirect systems are a viable alternative for heating broiler houses in terms of flock performance, bird welfare and food safety.展开更多
Environmental conditions determine woody plant life such as species diversity,structure and regeneration status.This research aimed to assess the impact of environmental conditions on woody plant species diversity,str...Environmental conditions determine woody plant life such as species diversity,structure and regeneration status.This research aimed to assess the impact of environmental conditions on woody plant species diversity,structure and regeneration in forest patches of Guna Mountain:the case of Este District,South Gondar Zone,north-west Ethiopia.A total of 71 square sample plots(400 m~2 each) were established at 10 transects laid in five forest patches of the study area to collect vegetation data including the abundance of species,height and diameter at breast height(DBH).Environmental data including available potassium,available phosphorus,cation exchange capacity,soil texture,electrical conductivity,soil acidity,total nitrogen,organic matter,organic carbon,sodium adsorption ratio,exchangeable sodium percentage,bulk density,aspect,elevation,slope,latitude and longitude data were collected in the same plots.A correlation analysis between vegetation and environmental data was performed using rcorr(x) function in package Hmisc in R Programming Language.The most pronounced impacts were observed in altitude,grazing and pH,positively and silt,sand,electrical conductivity and cation exchange capacity,negatively.In addition,strong and significant impacts on plant structure were also observed due to the variation in soil texture and p H.The difference in aspect,sand and slope also impacted plant regeneration.The study showed that environmental parameters influence the diversity,structure and regeneration of woody plants.These parameters can be considered in the rehabilitation of the vegetation cover and conservation efforts of the rare woody species.Conservation measures that can minimalize the negative influences of environmental conditions can be applied through collaboration with communities around the forest patches.展开更多
Return period is generally adopted to calculate the design value of environmental condition in offshore structure design. However, it can not make relevant adjustment according to structure＇s, especially the mobile u...Return period is generally adopted to calculate the design value of environmental condition in offshore structure design. However, it can not make relevant adjustment according to structure＇s, especially the mobile unit＇s, life time or its operation areas and usually make the design either insufficiently safe or rather uneconomical. A formula is developed to solve this problem in the case of the design wave height, where the risk, the design life, the distributions of wave heights in operation areas and the operating durations in each area are regarded as parameters. The applications of this method and the comparisons with the general method are presented. The result of this method is considered to be proper.展开更多
Environmental conditions determining the timing of the lifetime maximum intensities of tropical cyclones(TCs)are investigated for the TCs over the western North Pacific during the period 2008-2017.The results show tha...Environmental conditions determining the timing of the lifetime maximum intensities of tropical cyclones(TCs)are investigated for the TCs over the western North Pacific during the period 2008-2017.The results show that the land controls the timings of the lifetime maximum intensities in 42% of the TCs over this basin,indicating that accurate track forecasts are beneficial for TC intensity forecasts.With respect to other TCs that are not affected by the land(i.e.,Ocean-TCs),the timings of their lifetime maximum intensities are determined by multiple oceanic factors.In particular,interactions between TCs and cold-core eddies occur in a large proportion(nearly 60%)of Ocean-TCs at or shortly after the times of their lifetime maximum intensities,especially in strong TCs(categories 4 and 5),suggesting that a consideration of the above interactions is necessary for improving TC intensity forecasting skills.In addition,unfavorable oceanic heat content conditions become common as the latitude increases over 25°N,influencing half of the Ocean-TCs.Strong vertical wind shear contributes detrimentally to the atmospheric environment in 17% of the TCs over this basin,especially in moderate and weak TCs.In contrast,neither the maximum potential intensity nor the humidity in the middle level of the atmosphere plays dominant roles when TCs turn from their peak intensities to weakening.展开更多
The project ＂environmental conditions and behaviour depending on income and purchasing power＂ analysed the correlation between environmental impacts （e.g. noise, dust） or environmental behaviour （purchase of orga...The project ＂environmental conditions and behaviour depending on income and purchasing power＂ analysed the correlation between environmental impacts （e.g. noise, dust） or environmental behaviour （purchase of organic food, usage of public transport） and household income. Statistical matching was used to add income variables from EU-SILC to the the Micro Census （MC） environment dataset 2011. For each respondent of the MC environment a donor from the data from EU-SILC with minimal distance was found. Several matching options were tested to find the best option to link the variable ＂total disposable household income＂ to the environmental data. The machting options differed in the used distance function, which depended on the selected matching variables and their weight. The analysis provided an insight into advantages or problems of the method of statistical matching. Analyses of the environmental responses by household income terciles revealed significant differences in the assessment of quality of life, disturbance by noise, purchase of ecological products or the use of public transport.展开更多
Ultrasonic guided wave is an attractive monitoring technique for large-scale structures but is vulnerable to changes in environmental and operational conditions(EOC),which are inevitable in the normal inspection of ci...Ultrasonic guided wave is an attractive monitoring technique for large-scale structures but is vulnerable to changes in environmental and operational conditions(EOC),which are inevitable in the normal inspection of civil and mechanical structures.This paper thus presents a robust guided wave-based method for damage detection and localization under complex environmental conditions by singular value decomposition-based feature extraction and one-dimensional convolutional neural network(1D-CNN).After singular value decomposition-based feature extraction processing,a temporal robust damage index(TRDI)is extracted,and the effect of EOCs is well removed.Hence,even for the signals with a very large temperature-varying range and low signal-to-noise ratios(SNRs),the final damage detection and localization accuracy retain perfect 100%.Verifications are conducted on two different experimental datasets.The first dataset consists of guided wave signals collected from a thin aluminum plate with artificial noises,and the second is a publicly available experimental dataset of guided wave signals acquired on a composite plate with a temperature ranging from 20℃to 60℃.It is demonstrated that the proposed method can detect and localize the damage accurately and rapidly,showing great potential for application in complex and unknown EOC.展开更多
In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs bro...In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs brought large-scale heavy rainfall to North China,with daily precipitation exceeding 100 mm.Using reanalysis datasets and gridded precipitation data,the ETCs that affected Central and Eastern China during the boreal midsummer from 1981 to 2020 were objectively identified and tracked.ETCs causing precipitation were classified based on maximum daily precipitation,resulting in datasets for ETCs with torrential rain(daily precipitation exceeding 100 mm,referred to as ETC_R100)and heavy rain(daily precipitation exceeding 25 mm,referred to as ETC_R25).Comparative analysis can help highlight the characteristics of ETC_R100.This study compares the spatial distribution,movement paths,weather impacts,large-scale atmospheric circulation,and environmental conditions of these two types of precipitation-related ETCs.The following findings emerged:(1)ETC_R100 is driven by the combined forcing of upper-level troughs and warm-moist airflows at lower levels,exhibiting stronger thermal forcing than ETC_R25.(2)The moisture source for ETC_R100 are the Bay of Bengal and the Northwest Pacific,with moisture transported via the South China Sea.Compared to ETCs with nonextreme rainfall,ETC_R100 is characterized by greater atmospheric instability and better moisture conditions,resulting in higher precipitation intensity.(3)Regardless of the precipitation level,ETCs affected different regions but contributed significantly to precipitation in northern China,accounting for approximately 50%of the total precipitation.The results indicate that ETC_R100 differs significantly from ETCs with varying levels of precipitation in terms of statistical characteristics,weather impact,environmental conditions,and cyclogenesis conditions.展开更多
Based on the significant weather report,CG lightning,composite radar reflectivity,and ERA5 reanalysis data,we first studied the spatiotemporal distribution characteristics of four types(only severe convective wind(SCW...Based on the significant weather report,CG lightning,composite radar reflectivity,and ERA5 reanalysis data,we first studied the spatiotemporal distribution characteristics of four types(only severe convective wind(SCW);SCW and hail;SCW and short-duration heavy rainfall(SDHR);and SCW,hail,and SDHR)of convective weather events related to SCW during the warm season(May to September)from 2011 to 2018 in North China.Second,severe convective cases producing SCW were selected to statistically analyze the initiation,decay,lifetime,and organizational characteristics of convective systems.Finally,using ERA5 reanalysis data and conventional surface observation data,preconvective soundings were constructed to explore the differences in environmental conditions for initiating convective systems between SCW and non-SCW.The results indicate that mixed-type of SCW and SDHR events occur more frequently over plains,while other types of convective weather occur more frequently over mountains.The frequency peak of SCW occurs in June,while mixed convective weather peaks in July.The initiation time of convective systems is concentrated between 1000 and 1300 BST,with a peak at 1200 BST.Over mountains,the daily peaks of ordinary and significant SCW generally occur at 1700-1800 BST and 1600-1700 BST,respectively,while over plains,the peak of ordinary SCW typically lags behind that of mountains by 1-2 hours.Additionally,SCW systems are mainly initiated over mountains,with most lifetimes lasting 7–13 hours.Nonlinear convective systems produce the most SCW events,followed by trailing-stratiform convective systems.The convective available potential energy(CAPE),downdraft convective available potential energy,and the temperature difference between 850 and 500 hPa can all distinguish between SCW systems and non-SCW systems occurring over plains.Compared to non-SCW convective systems,SCW convective systems over mountains are more likely to occur in environments with less precipitable water,while SCW convective systems over plains are more likely to occur in environments with higher CAPE and stronger deep-layer wind shear.展开更多
The photo-aging behavior of microplastics(MPs)in natural environment has become a global concern.The ultraviolet radiation has enough energy to change the polymer structure and physicalchemical properties of MPs.Less ...The photo-aging behavior of microplastics(MPs)in natural environment has become a global concern.The ultraviolet radiation has enough energy to change the polymer structure and physicalchemical properties of MPs.Less attention has focused on the interactions of the photo-aged polar and biodegradable MPs with organic pollutants.This work investigated the structural properties of aged polar polyamide(PA)MPs and biodegradable polylactic acid(PLA)MPs exposed to ultraviolet irradiation and their adsorption behavior and mechanism for neonicotinoid insecticide imidacloprid(IMI).The results showed that the MPs had extensive changes in surface morphology and chemical properties after photo-aging.The C–N bond of PA MPs was disrupted to form more carbonyl groups.The oxygen-containing functional groups on the surface of aged PLA MPs were broken and generated relatively smaller molecules.The adsorption capacity of IMI on PA MPs decreased by 19.2%,while the adsorption capacity of IMI on PLA MPs increased by 41.2%after photo-aging.This depended on the natural structure of the MPs and their ability to absorb ultraviolet light.The electrostatic interactions,hydrogen bonds,van der Waals interactions,and polar-polar interactions were the main adsorption mechanisms of IMI on MPs.High initial solution pH and low ionic strength favored the adsorption of IMI by altering charge distribution on the MPs surface.The formation of the humic acid-IMI complexes decreased the concentration of IMI in the water phase and further decreased the adsorption on MPs.These results are enlightening for a scientific comprehension of the environmental behavior of the polar MPs.展开更多
The foraging strategy at abundant resources of the social wasp Vespula germanica includes scanning in the direction of the nest while memorizing resource-specific landmarks and contextual cues.In the present study,we ...The foraging strategy at abundant resources of the social wasp Vespula germanica includes scanning in the direction of the nest while memorizing resource-specific landmarks and contextual cues.In the present study,we sought to explore wasps'behavioral plasticity on foraging trips to resources whose location and composition changed after a single visit.We evaluated how contextual modifications of food displacement and replacements 60 cm apart from the original site,affect re-orientation for re-finding previously memorized food resources.The results showed that wasps detected and collected the resource faster when more changes were introduced on the following visit.If returning foragers discovered several modifications on both the location and the kind of resource,they collected food more rapidly from the displaced dish,than if only a single parameter in the environment had been changed.These findings illustrate the grade of behavioral plasticity in V.germanica while foraging on abundant resources,which may contribute to the understanding of the prodigious invasive success of this species in anthropized environments.展开更多
Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enh...Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enhance the performance of guided wave damage detection in noisy environments is crucial.This paper introduces a local temporal principal component analysis(PCA)reconstruction approach for denoising guided waves prior to implementing unsupervised damage detection,achieved through novel autoencoder-based reconstruction.Experimental results demonstrate that the proposed denoising method significantly enhances damage detection performance when guided waves are contaminated by noise,with SNR values ranging from 10 to-5 dB.Following the implementation of the proposed denoising approach,the AUC score can elevate from 0.65 to 0.96 when dealing with guided waves corrputed by noise at a level of-5 dB.Additionally,the paper provides guidance on selecting the appropriate number of components used in the denoising PCA reconstruction,aiding in the optimization of the damage detection in noisy conditions.展开更多
Since ancient times,humanity has yearned for longevity,viewing health and long life as enduring aspirations.Research has shown that longevity genes may be passed down through certain populations(Costa D,2019).However,...Since ancient times,humanity has yearned for longevity,viewing health and long life as enduring aspirations.Research has shown that longevity genes may be passed down through certain populations(Costa D,2019).However,genetics alone is not the decisive factor-environmental conditions also play a vital role in achieving a long life(Selinus O,2013).展开更多
The sap flow method is widely used to estimate forest transpiration.However,at the individual tree level it has spatiotemporal variations due to the impacts of environmental conditions and spatial relationships among ...The sap flow method is widely used to estimate forest transpiration.However,at the individual tree level it has spatiotemporal variations due to the impacts of environmental conditions and spatial relationships among trees.Therefore,an in-depth understanding of the coupling effects of these factors is important for designing sap flow measurement methods and performing accurate assessments of stand scale transpiration.This study is based on observations of sap flux density(SF_(d))of nine sample trees with different Hegyi’s competition indices(HCIs),soil moisture,and meteorological conditions in a pure plantation of Larix gmelinii var.principis-rupprechtii during the 2021 growing season(May to September).A multifactorial model of sap flow was developed and possible errors in the stand scale sap flow estimates associated with sample sizes were determined using model-based predictions of sap flow.Temporal variations are controlled by vapour pressure deficit(VPD),solar radiation(R),and soil moisture,and these relationships can be described by polynomial or saturated exponential functions.Spatial(individual)differences were influenced by the HCI,as shown by the decaying power function.A simple SF_(d)model at the individual tree level was developed to describe the synergistic influences of VPD,R,soil moisture,and HCI.The coefficient of variations(CV)of the sap flow estimates gradually stabilized when the sample size was>10;at least six sample trees were needed if the CV was within 10%.This study improves understanding of the mechanisms of spatiotemporal variations in sap flow at the individual tree level and provides a new methodology for determining the optimal sample size for sap flow measurements.展开更多
WEIFANG City of east China’s Shandong Province is located in the central part of the Shandong Peninsula,bordering the Bohai Sea to the north and the Yellow Sea to the south.In springtime,the region sees little rainfa...WEIFANG City of east China’s Shandong Province is located in the central part of the Shandong Peninsula,bordering the Bohai Sea to the north and the Yellow Sea to the south.In springtime,the region sees little rainfall yet many windy days,with a single prevailing wind direction and minimal turbulence-an environmental condition ideal for kite flying.展开更多
The Argentine shortfin squid Illex argentinus is an economically important short-lived species widely distributed in the southwest Atlantic Ocean.The abundance and distribution of I.argentinus are associated with clim...The Argentine shortfin squid Illex argentinus is an economically important short-lived species widely distributed in the southwest Atlantic Ocean.The abundance and distribution of I.argentinus are associated with climate change and environmental fluctuations.The potential distribution of I.argentinus was modeled with various environmental variables including sea surface temperature(SST),sea surface height(SSH),chlorophyll a,sea surface salinity(SSS),net primary productivity(NPP),mixed layer depth(MLD),eddy kinetic energy(EKE),and photosynthetically active radiation(PAR)using the maximum entropy(MaxEnt)approach during the peak fishing seasons(January–April).The habitat suitability index(HSI)was defined as the probability of species emergence from the MaxEnt model and the area of HSI≥0.6 was regarded as suitable.Results indicate that the predicted habitat correlated with the actual fishing position,with similar trends in the percentages of suitable habitats and catch per unit effort(CPUE)of I.argentinus from January to April.Moreover,SST,SSH,PAR,and MLD were identified critical environmental variables for the distribution of I.argentinus.In addition,the median of preferred ranges of the critical environmental variables were concentrated within the suitable habitats of I.argentinus.The Area under the Receiver Operating Characteristic Curve(AUC)was greater than 0.96 for all four months.Variations in latitudinal and longitudinal gravity centers(LATG and LONG)of fishing effort were consistent with latitudinal and longitudinal gravity centers(LATG_H and LONG_H)of the HSI.Our findings suggest that the MaxEnt model is an effective tool to predict the potential distribution of I.argentinus.Meanwhile,SST,SSH,PAR,and MLD should be given with more extensive attention in predicting the potential distribution of I.argentinus,as they are important environmental indicators that can help decision-makers search for the fishing ground of I.argentinus in the Southwest Atlantic.展开更多
As shallow resources are increasingly depleted,the mechanics'theory and testing technology of deep insitu rock has become urgent.Traditional coring technologies obtain rock samples without retaining the in-situ en...As shallow resources are increasingly depleted,the mechanics'theory and testing technology of deep insitu rock has become urgent.Traditional coring technologies obtain rock samples without retaining the in-situ environmental conditions,leading to distortion of the measured parameters.Herein,a coring and testing systems retaining in-situ geological conditions is presented:the coring system that obtains in-situ rock samples,and the transfer and testing system that stores and analyzes the rocks under a reconstructed environment.The ICP-Coring system mainly consists of the pressure controller,active insulated core reactor and insulation layer and sealing film.The ultimate bearing strength of 100 MPa for pressurepreservation,temperature control accuracy of 0.97%for temperature-retained are realized.CH_(4)and CO permeability of the optimized sealing film are as low as 3.85 and 0.33 ppm/min.The average tensile elongation of the film is 152.4%and the light transmittance is reduced to 0%.Additionally,the pressure and steady-state temperature accuracy for reconstructing the in-situ environment of transfer and storage system up to 1%and±0.2 is achieved.The error recorded of the noncontact sensor ring made of lowdensity polymer is less than 6%than that of the contact test.The system can provide technical support for the deep in-situ rock mechanics research,improving deep resource acquisition capabilities and further clarifying deep-earth processes.展开更多
During 1995-2011, annual production of winter-spring cohort of Ommastrephes bartramii for Chinese squidjigging fishery has greatly fluctuated, which is closely related to the environmental conditions on the spawning a...During 1995-2011, annual production of winter-spring cohort of Ommastrephes bartramii for Chinese squidjigging fishery has greatly fluctuated, which is closely related to the environmental conditions on the spawning and fishing grounds. To better understand how squid recruitment and abundance were infuenced by ocean environmental conditions, biological and physical environmental variables including sea surface temperature （SST）, SST anomaly （SSTA）, chlorophyll a （Chl a） concentration and the Kuroshio Current were examined during years with the highest （1999）, intermediate （2005）, and lowest （2009） catches. Catch per unit effort （CPUE） of the squid-jigging vessels was used as an indicator of squid abundance. The results indicated that high SST and Chl a concentration on the spawning ground in 1999 resulted in favorable incubation and feeding conditions for squid recruitment. Whereas the suitable spawning zone （SSZ） in 2009 shifted southward and coincided with low SST and Chl a concentration, resulting in a reduction in the squid recruitment. The small difference of SSZ area in the three years suggested the SSZ provided limited influences on the variability in squid recruitment. Furthermore, high squid abundance in 1999 and 2005 was associated with warm SSTA on the fishing ground. While the cool SSTA on the fishing ground in 2009 contributed to adverse habitat for the squid, leading to extremely low abundance. It was inferred that strengthened intensity of the Kuroshio force generally yielded favorable environmental conditions for O. bartramii. Future research are suggested to focus on the fundamental research oil the early life stage of O. bartramii and mechanism of how the ocean-climate variability affects the squid abundance and spatial distribution by coupling physical model with squid biological process to explore transport path and abundance distribution.展开更多
Chemometric approach based on principal component analysis（PCA） was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River（Pearl River） Estuary and adjacent...Chemometric approach based on principal component analysis（PCA） was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River（Pearl River） Estuary and adjacent waters（ZREAW） in the South China Sea. The PCA result shows that the ZREAW can be divided into different zones according to the principal components and geographical locations of the study stations,and indicates that there are distinct regional variances on environmental features and the corresponding phytoplankton biomass and community structures among different areas. The spatial distribution of ecological features was implied to be influenced by various degrees of the different water resources,such as the Pearl River discharges,the coastal current and the oceanic water from the South China Sea. The variation of the biomass maximum zone and the complex impacts on the spatial distributions of phytoplankton biomass and production were also evaluated.展开更多
The chemistry of sedimentary organic phosphorus（OP） and its fraction distribution in sediments are greatly influenced by environmental conditions such as terrestrial inputs and runoffs. The linkage of OP with enviro...The chemistry of sedimentary organic phosphorus（OP） and its fraction distribution in sediments are greatly influenced by environmental conditions such as terrestrial inputs and runoffs. The linkage of OP with environmental conditions was analyzed on the basis of OP spatial and historical distributions in lake sediments. The redundancy analysis and OP spatial distribution results suggested that both Na OH-OP（OP extracted by Na OH） and Re-OP（residual OP） in surface sediments from the selected 13 lakes reflected the gradient effects of environmental conditions and the autochthonous and/or allochthonous inputs driven by latitude zonality in China. The lake level and salinity of Lake Hulun and the runoff and precipitation of its drainage basin were reconstructed on the basis of the geochemistry index. This work showed that a gradient in weather conditions presented by the latitude zonality in China impacts the OP accumulation through multiple drivers and in many ways.The drivers are mainly precipitation and temperature, governing organic matter（OM）production, degradation rate and transportation in the watershed. Over a long temporal dimension（4000 years）, the vertical distributions of Re-OP and Na OH-OP based on a dated sediment profile from HLH were largely regulated by the autochthonous and/or allochthonous inputs, which depended on the environmental and climate conditions and anthropogenic activities in the drainage basin. This work provides useful environmental geochemistry information to understand the inherent linkage of OP fractionation with environmental conditions and lake evolution.展开更多
Accurate leaf area simulation is critical for the performance of crop growth models. Area of fully expanded individual leaves of maize hybrids released before 1995 (defined as old hybrids) has been simulated using a b...Accurate leaf area simulation is critical for the performance of crop growth models. Area of fully expanded individual leaves of maize hybrids released before 1995 (defined as old hybrids) has been simulated using a bell-shaped function (BSF) and the relationship between its parameters and total leaf number (TLNO). However, modern high-yielding maize hybrids show different canopy architectures. The function parameters calibrated for old hybrids will not accurately represent modern hybrids. In this study, we evaluated these functions using a dataset including old and modern hybrids that have been widely planted in China in recent years. Maximum individual leaf area (Y_0) and corresponding leaf position (X_0) were not predicted well by TLNO (R^2= 0.56 and R^2= 0.70) for modern hybrids. Using recalibrated shape parameters a and b with values of Y_0 and X_0 for modern hybrids, the BSF accurately predicted individual leaf area (R^2= 0.95–0.99) and total leaf area of modern hybrids (R^2= 0.98). The results show that the BSF is still a robust way to predict the fully expanded leaf area of maize when parameters a and b are modified and Y_0 and X_0 are fitted. Breeding programs have led to increases in TLNO of maize but have not altered Y_0 and X_0, reducing the correlation between Y_0, X_0, and TLNO. For modern hybrids, the values of Y_0 and X_0 are hybrid-specific. Modern hybrids tend to have less-negative values of parameter a and more-positive values of parameter b in the leaf profile. Growth conditions, such as plant density and environmental conditions, also affect the fully expanded leaf area but were not considered in the original published equations. Thus, further research is needed to accurately estimate values of Y_0 and X_0 of individual modern hybrids to improve simulation of maize leaf area in crop growth models.展开更多
基金the Food Institutional Research Measure(FIRM)Programme administered by the Irish Department of Agriculture,Food and Marine for funding this study(11SF328)
文摘This study compared the impact of three indirect heating systems to direct gas flame heaters on a selection of flock performance and environmental indicators in commercial broiler units. No statistically significant differences（P≥0.05） were found in flock mortality rates, bird weight, water consumption, stress response, carbon dioxide, ammonia, temperature, relative humidity, litter quality, within-flock Campylobacter levels or mean Campylobacter counts when flock data from any of the three indirect heating systems were compared to flocks reared in houses with direct heating systems. Differences in litter quality were observed between upper and lower litter layers in all houses, regardless of heating type, which may have implications for bird health and welfare. Carbon dioxide concentrations in houses with direct heating systems were significantly higher than those in houses with indirect heating systems during the first 10 days of bird life（P≤0.05）. This was due to the increased use of heating systems during this period of the flock cycle. Differences in CO2 concentrations had no effect on flock performance, possibly due to the fact that concentrations did not exceed known safe levels. A statistically significant increase in stress response was observed in birds as a result of partial depopulation（thinning） within houses, irrespective of heating system type used（P≤0.05）. Stress associated with thinning may have consequences for bird welfare and food safety. In conclusion, the results of our study suggest that indirect heating systems do not appear to negatively impact on flock performance, stress response, within-flock Campylobacter levels or mean Campylobacter counts and do not appear to significantly alter environmental conditions within broiler houses when compared to houses equipped with direct heating systems. Indirect systems are a viable alternative for heating broiler houses in terms of flock performance, bird welfare and food safety.
基金Addis Ababa UniversityDebre Tabor University,both in Ethiopia,for their sponsorship of the study。
文摘Environmental conditions determine woody plant life such as species diversity,structure and regeneration status.This research aimed to assess the impact of environmental conditions on woody plant species diversity,structure and regeneration in forest patches of Guna Mountain:the case of Este District,South Gondar Zone,north-west Ethiopia.A total of 71 square sample plots(400 m~2 each) were established at 10 transects laid in five forest patches of the study area to collect vegetation data including the abundance of species,height and diameter at breast height(DBH).Environmental data including available potassium,available phosphorus,cation exchange capacity,soil texture,electrical conductivity,soil acidity,total nitrogen,organic matter,organic carbon,sodium adsorption ratio,exchangeable sodium percentage,bulk density,aspect,elevation,slope,latitude and longitude data were collected in the same plots.A correlation analysis between vegetation and environmental data was performed using rcorr(x) function in package Hmisc in R Programming Language.The most pronounced impacts were observed in altitude,grazing and pH,positively and silt,sand,electrical conductivity and cation exchange capacity,negatively.In addition,strong and significant impacts on plant structure were also observed due to the variation in soil texture and p H.The difference in aspect,sand and slope also impacted plant regeneration.The study showed that environmental parameters influence the diversity,structure and regeneration of woody plants.These parameters can be considered in the rehabilitation of the vegetation cover and conservation efforts of the rare woody species.Conservation measures that can minimalize the negative influences of environmental conditions can be applied through collaboration with communities around the forest patches.
基金the National Great Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China During the 11th Five-year Plan (No. 2006BAA01A25)
文摘Return period is generally adopted to calculate the design value of environmental condition in offshore structure design. However, it can not make relevant adjustment according to structure＇s, especially the mobile unit＇s, life time or its operation areas and usually make the design either insufficiently safe or rather uneconomical. A formula is developed to solve this problem in the case of the design wave height, where the risk, the design life, the distributions of wave heights in operation areas and the operating durations in each area are regarded as parameters. The applications of this method and the comparisons with the general method are presented. The result of this method is considered to be proper.
基金National Key Research and Development Program of China(2018YFC1506402)National Natural Scientific Foundations of China(41575061,41775061)JSPS KAKENHI(JP18H01283)。
文摘Environmental conditions determining the timing of the lifetime maximum intensities of tropical cyclones(TCs)are investigated for the TCs over the western North Pacific during the period 2008-2017.The results show that the land controls the timings of the lifetime maximum intensities in 42% of the TCs over this basin,indicating that accurate track forecasts are beneficial for TC intensity forecasts.With respect to other TCs that are not affected by the land(i.e.,Ocean-TCs),the timings of their lifetime maximum intensities are determined by multiple oceanic factors.In particular,interactions between TCs and cold-core eddies occur in a large proportion(nearly 60%)of Ocean-TCs at or shortly after the times of their lifetime maximum intensities,especially in strong TCs(categories 4 and 5),suggesting that a consideration of the above interactions is necessary for improving TC intensity forecasting skills.In addition,unfavorable oceanic heat content conditions become common as the latitude increases over 25°N,influencing half of the Ocean-TCs.Strong vertical wind shear contributes detrimentally to the atmospheric environment in 17% of the TCs over this basin,especially in moderate and weak TCs.In contrast,neither the maximum potential intensity nor the humidity in the middle level of the atmosphere plays dominant roles when TCs turn from their peak intensities to weakening.
文摘The project ＂environmental conditions and behaviour depending on income and purchasing power＂ analysed the correlation between environmental impacts （e.g. noise, dust） or environmental behaviour （purchase of organic food, usage of public transport） and household income. Statistical matching was used to add income variables from EU-SILC to the the Micro Census （MC） environment dataset 2011. For each respondent of the MC environment a donor from the data from EU-SILC with minimal distance was found. Several matching options were tested to find the best option to link the variable ＂total disposable household income＂ to the environmental data. The machting options differed in the used distance function, which depended on the selected matching variables and their weight. The analysis provided an insight into advantages or problems of the method of statistical matching. Analyses of the environmental responses by household income terciles revealed significant differences in the assessment of quality of life, disturbance by noise, purchase of ecological products or the use of public transport.
基金Supported by National Natural Science Foundation of China(Grant Nos.52272433 and 11874110)Jiangsu Provincial Key R&D Program(Grant No.BE2021084)Technical Support Special Project of State Administration for Market Regulation(Grant No.2022YJ11).
文摘Ultrasonic guided wave is an attractive monitoring technique for large-scale structures but is vulnerable to changes in environmental and operational conditions(EOC),which are inevitable in the normal inspection of civil and mechanical structures.This paper thus presents a robust guided wave-based method for damage detection and localization under complex environmental conditions by singular value decomposition-based feature extraction and one-dimensional convolutional neural network(1D-CNN).After singular value decomposition-based feature extraction processing,a temporal robust damage index(TRDI)is extracted,and the effect of EOCs is well removed.Hence,even for the signals with a very large temperature-varying range and low signal-to-noise ratios(SNRs),the final damage detection and localization accuracy retain perfect 100%.Verifications are conducted on two different experimental datasets.The first dataset consists of guided wave signals collected from a thin aluminum plate with artificial noises,and the second is a publicly available experimental dataset of guided wave signals acquired on a composite plate with a temperature ranging from 20℃to 60℃.It is demonstrated that the proposed method can detect and localize the damage accurately and rapidly,showing great potential for application in complex and unknown EOC.
基金National Natural Science Foundation of China(42375014,42088101,42030605)Joint Research Project for Meteorological Capacity Improvement(24NLTSZ010)Young Elite Scientists Sponsorship Program by BAST(BYESS2023205)。
文摘In recent years,torrential rain events caused by extratropical cyclones(ETCs)during the boreal midsummer(July-August)in Central and Eastern China have shown an increasing trend.For instence,in August 2024,two ETCs brought large-scale heavy rainfall to North China,with daily precipitation exceeding 100 mm.Using reanalysis datasets and gridded precipitation data,the ETCs that affected Central and Eastern China during the boreal midsummer from 1981 to 2020 were objectively identified and tracked.ETCs causing precipitation were classified based on maximum daily precipitation,resulting in datasets for ETCs with torrential rain(daily precipitation exceeding 100 mm,referred to as ETC_R100)and heavy rain(daily precipitation exceeding 25 mm,referred to as ETC_R25).Comparative analysis can help highlight the characteristics of ETC_R100.This study compares the spatial distribution,movement paths,weather impacts,large-scale atmospheric circulation,and environmental conditions of these two types of precipitation-related ETCs.The following findings emerged:(1)ETC_R100 is driven by the combined forcing of upper-level troughs and warm-moist airflows at lower levels,exhibiting stronger thermal forcing than ETC_R25.(2)The moisture source for ETC_R100 are the Bay of Bengal and the Northwest Pacific,with moisture transported via the South China Sea.Compared to ETCs with nonextreme rainfall,ETC_R100 is characterized by greater atmospheric instability and better moisture conditions,resulting in higher precipitation intensity.(3)Regardless of the precipitation level,ETCs affected different regions but contributed significantly to precipitation in northern China,accounting for approximately 50%of the total precipitation.The results indicate that ETC_R100 differs significantly from ETCs with varying levels of precipitation in terms of statistical characteristics,weather impact,environmental conditions,and cyclogenesis conditions.
基金supported by the National Natural Science Foundation of China(Grant Nos.42375008,41975056,42005006)the National Key Scientific and Technological Infrastructure Project“Earth System Numerical Simulation Facility”(EarthLab)the Beijing Municipal Natural Science Foundation(Grant No.8222079)。
文摘Based on the significant weather report,CG lightning,composite radar reflectivity,and ERA5 reanalysis data,we first studied the spatiotemporal distribution characteristics of four types(only severe convective wind(SCW);SCW and hail;SCW and short-duration heavy rainfall(SDHR);and SCW,hail,and SDHR)of convective weather events related to SCW during the warm season(May to September)from 2011 to 2018 in North China.Second,severe convective cases producing SCW were selected to statistically analyze the initiation,decay,lifetime,and organizational characteristics of convective systems.Finally,using ERA5 reanalysis data and conventional surface observation data,preconvective soundings were constructed to explore the differences in environmental conditions for initiating convective systems between SCW and non-SCW.The results indicate that mixed-type of SCW and SDHR events occur more frequently over plains,while other types of convective weather occur more frequently over mountains.The frequency peak of SCW occurs in June,while mixed convective weather peaks in July.The initiation time of convective systems is concentrated between 1000 and 1300 BST,with a peak at 1200 BST.Over mountains,the daily peaks of ordinary and significant SCW generally occur at 1700-1800 BST and 1600-1700 BST,respectively,while over plains,the peak of ordinary SCW typically lags behind that of mountains by 1-2 hours.Additionally,SCW systems are mainly initiated over mountains,with most lifetimes lasting 7–13 hours.Nonlinear convective systems produce the most SCW events,followed by trailing-stratiform convective systems.The convective available potential energy(CAPE),downdraft convective available potential energy,and the temperature difference between 850 and 500 hPa can all distinguish between SCW systems and non-SCW systems occurring over plains.Compared to non-SCW convective systems,SCW convective systems over mountains are more likely to occur in environments with less precipitable water,while SCW convective systems over plains are more likely to occur in environments with higher CAPE and stronger deep-layer wind shear.
基金This work was supported by the National Natural Science Foundation of China(No.41977142)Major Science and Technology Program for Water Pollution Control and Treatment(No.2018ZX07111003).
文摘The photo-aging behavior of microplastics(MPs)in natural environment has become a global concern.The ultraviolet radiation has enough energy to change the polymer structure and physicalchemical properties of MPs.Less attention has focused on the interactions of the photo-aged polar and biodegradable MPs with organic pollutants.This work investigated the structural properties of aged polar polyamide(PA)MPs and biodegradable polylactic acid(PLA)MPs exposed to ultraviolet irradiation and their adsorption behavior and mechanism for neonicotinoid insecticide imidacloprid(IMI).The results showed that the MPs had extensive changes in surface morphology and chemical properties after photo-aging.The C–N bond of PA MPs was disrupted to form more carbonyl groups.The oxygen-containing functional groups on the surface of aged PLA MPs were broken and generated relatively smaller molecules.The adsorption capacity of IMI on PA MPs decreased by 19.2%,while the adsorption capacity of IMI on PLA MPs increased by 41.2%after photo-aging.This depended on the natural structure of the MPs and their ability to absorb ultraviolet light.The electrostatic interactions,hydrogen bonds,van der Waals interactions,and polar-polar interactions were the main adsorption mechanisms of IMI on MPs.High initial solution pH and low ionic strength favored the adsorption of IMI by altering charge distribution on the MPs surface.The formation of the humic acid-IMI complexes decreased the concentration of IMI in the water phase and further decreased the adsorption on MPs.These results are enlightening for a scientific comprehension of the environmental behavior of the polar MPs.
基金the Universidad Nacional del Comahue(CRUB)and INIBIOMA-CONICET.
文摘The foraging strategy at abundant resources of the social wasp Vespula germanica includes scanning in the direction of the nest while memorizing resource-specific landmarks and contextual cues.In the present study,we sought to explore wasps'behavioral plasticity on foraging trips to resources whose location and composition changed after a single visit.We evaluated how contextual modifications of food displacement and replacements 60 cm apart from the original site,affect re-orientation for re-finding previously memorized food resources.The results showed that wasps detected and collected the resource faster when more changes were introduced on the following visit.If returning foragers discovered several modifications on both the location and the kind of resource,they collected food more rapidly from the displaced dish,than if only a single parameter in the environment had been changed.These findings illustrate the grade of behavioral plasticity in V.germanica while foraging on abundant resources,which may contribute to the understanding of the prodigious invasive success of this species in anthropized environments.
基金National Science Foundation of Zhejiang under Contract(LY23E010001)。
文摘Structural health monitoring is widely utilized in outdoor environments,especially under harsh conditions,which can introduce noise into the monitoring system.Therefore,designing an effective denoising strategy to enhance the performance of guided wave damage detection in noisy environments is crucial.This paper introduces a local temporal principal component analysis(PCA)reconstruction approach for denoising guided waves prior to implementing unsupervised damage detection,achieved through novel autoencoder-based reconstruction.Experimental results demonstrate that the proposed denoising method significantly enhances damage detection performance when guided waves are contaminated by noise,with SNR values ranging from 10 to-5 dB.Following the implementation of the proposed denoising approach,the AUC score can elevate from 0.65 to 0.96 when dealing with guided waves corrputed by noise at a level of-5 dB.Additionally,the paper provides guidance on selecting the appropriate number of components used in the denoising PCA reconstruction,aiding in the optimization of the damage detection in noisy conditions.
文摘Since ancient times,humanity has yearned for longevity,viewing health and long life as enduring aspirations.Research has shown that longevity genes may be passed down through certain populations(Costa D,2019).However,genetics alone is not the decisive factor-environmental conditions also play a vital role in achieving a long life(Selinus O,2013).
基金supported by the Fundamental Research Funds of the Chinese Academy of Forestry(CAFYBB2020QB004)the National Natural Science Foundation of China(41971038,32171559,U20A2085,and U21A2005).
文摘The sap flow method is widely used to estimate forest transpiration.However,at the individual tree level it has spatiotemporal variations due to the impacts of environmental conditions and spatial relationships among trees.Therefore,an in-depth understanding of the coupling effects of these factors is important for designing sap flow measurement methods and performing accurate assessments of stand scale transpiration.This study is based on observations of sap flux density(SF_(d))of nine sample trees with different Hegyi’s competition indices(HCIs),soil moisture,and meteorological conditions in a pure plantation of Larix gmelinii var.principis-rupprechtii during the 2021 growing season(May to September).A multifactorial model of sap flow was developed and possible errors in the stand scale sap flow estimates associated with sample sizes were determined using model-based predictions of sap flow.Temporal variations are controlled by vapour pressure deficit(VPD),solar radiation(R),and soil moisture,and these relationships can be described by polynomial or saturated exponential functions.Spatial(individual)differences were influenced by the HCI,as shown by the decaying power function.A simple SF_(d)model at the individual tree level was developed to describe the synergistic influences of VPD,R,soil moisture,and HCI.The coefficient of variations(CV)of the sap flow estimates gradually stabilized when the sample size was>10;at least six sample trees were needed if the CV was within 10%.This study improves understanding of the mechanisms of spatiotemporal variations in sap flow at the individual tree level and provides a new methodology for determining the optimal sample size for sap flow measurements.
文摘WEIFANG City of east China’s Shandong Province is located in the central part of the Shandong Peninsula,bordering the Bohai Sea to the north and the Yellow Sea to the south.In springtime,the region sees little rainfall yet many windy days,with a single prevailing wind direction and minimal turbulence-an environmental condition ideal for kite flying.
基金Supported by the Natural Science Foundation of Shanghai(No.23ZR1427100)the National Key R&D Program of China(No.2023YFD2401303)the Shanghai Talent Development Funding for the Project(No.2021078)。
文摘The Argentine shortfin squid Illex argentinus is an economically important short-lived species widely distributed in the southwest Atlantic Ocean.The abundance and distribution of I.argentinus are associated with climate change and environmental fluctuations.The potential distribution of I.argentinus was modeled with various environmental variables including sea surface temperature(SST),sea surface height(SSH),chlorophyll a,sea surface salinity(SSS),net primary productivity(NPP),mixed layer depth(MLD),eddy kinetic energy(EKE),and photosynthetically active radiation(PAR)using the maximum entropy(MaxEnt)approach during the peak fishing seasons(January–April).The habitat suitability index(HSI)was defined as the probability of species emergence from the MaxEnt model and the area of HSI≥0.6 was regarded as suitable.Results indicate that the predicted habitat correlated with the actual fishing position,with similar trends in the percentages of suitable habitats and catch per unit effort(CPUE)of I.argentinus from January to April.Moreover,SST,SSH,PAR,and MLD were identified critical environmental variables for the distribution of I.argentinus.In addition,the median of preferred ranges of the critical environmental variables were concentrated within the suitable habitats of I.argentinus.The Area under the Receiver Operating Characteristic Curve(AUC)was greater than 0.96 for all four months.Variations in latitudinal and longitudinal gravity centers(LATG and LONG)of fishing effort were consistent with latitudinal and longitudinal gravity centers(LATG_H and LONG_H)of the HSI.Our findings suggest that the MaxEnt model is an effective tool to predict the potential distribution of I.argentinus.Meanwhile,SST,SSH,PAR,and MLD should be given with more extensive attention in predicting the potential distribution of I.argentinus,as they are important environmental indicators that can help decision-makers search for the fishing ground of I.argentinus in the Southwest Atlantic.
基金supported by the Program for Guangdong Introducing Innovative and Enterpreneurial Teams(No.2019ZT08G315)National Natural Science Foundation of China(No.51827901,U2013603,and 52004166)。
文摘As shallow resources are increasingly depleted,the mechanics'theory and testing technology of deep insitu rock has become urgent.Traditional coring technologies obtain rock samples without retaining the in-situ environmental conditions,leading to distortion of the measured parameters.Herein,a coring and testing systems retaining in-situ geological conditions is presented:the coring system that obtains in-situ rock samples,and the transfer and testing system that stores and analyzes the rocks under a reconstructed environment.The ICP-Coring system mainly consists of the pressure controller,active insulated core reactor and insulation layer and sealing film.The ultimate bearing strength of 100 MPa for pressurepreservation,temperature control accuracy of 0.97%for temperature-retained are realized.CH_(4)and CO permeability of the optimized sealing film are as low as 3.85 and 0.33 ppm/min.The average tensile elongation of the film is 152.4%and the light transmittance is reduced to 0%.Additionally,the pressure and steady-state temperature accuracy for reconstructing the in-situ environment of transfer and storage system up to 1%and±0.2 is achieved.The error recorded of the noncontact sensor ring made of lowdensity polymer is less than 6%than that of the contact test.The system can provide technical support for the deep in-situ rock mechanics research,improving deep resource acquisition capabilities and further clarifying deep-earth processes.
基金The National High-Tech R&D Program(863 Program)of China under contract No.2012AA092303the Project of Shanghai Science and Technology Innovation under contract No.12231203900+4 种基金the Industrialization Program of National Development and Reform Commission under contract No.2159999the National Key Technologies R&D Program of China under contract No.2013BAD13B00the Shanghai Universities First-Class Disciplines Project(Fisheries A)the Funding Program for Outstanding Dissertations in Shanghai Ocean Universitythe Shanghai Ocean University International Center for Marine Studies
文摘During 1995-2011, annual production of winter-spring cohort of Ommastrephes bartramii for Chinese squidjigging fishery has greatly fluctuated, which is closely related to the environmental conditions on the spawning and fishing grounds. To better understand how squid recruitment and abundance were infuenced by ocean environmental conditions, biological and physical environmental variables including sea surface temperature （SST）, SST anomaly （SSTA）, chlorophyll a （Chl a） concentration and the Kuroshio Current were examined during years with the highest （1999）, intermediate （2005）, and lowest （2009） catches. Catch per unit effort （CPUE） of the squid-jigging vessels was used as an indicator of squid abundance. The results indicated that high SST and Chl a concentration on the spawning ground in 1999 resulted in favorable incubation and feeding conditions for squid recruitment. Whereas the suitable spawning zone （SSZ） in 2009 shifted southward and coincided with low SST and Chl a concentration, resulting in a reduction in the squid recruitment. The small difference of SSZ area in the three years suggested the SSZ provided limited influences on the variability in squid recruitment. Furthermore, high squid abundance in 1999 and 2005 was associated with warm SSTA on the fishing ground. While the cool SSTA on the fishing ground in 2009 contributed to adverse habitat for the squid, leading to extremely low abundance. It was inferred that strengthened intensity of the Kuroshio force generally yielded favorable environmental conditions for O. bartramii. Future research are suggested to focus on the fundamental research oil the early life stage of O. bartramii and mechanism of how the ocean-climate variability affects the squid abundance and spatial distribution by coupling physical model with squid biological process to explore transport path and abundance distribution.
基金The Knowledge Innovation Project of Chinese Academy of Sciences under contract Nos KZCX2-YW-Q07, KZCX2-YW-T001, KZCX2-YW-213 and SQ200805the National Natural Science Foundation of China under contract Nos U0633007, 40906057 and 40531006
文摘Chemometric approach based on principal component analysis（PCA） was utilized to examine the spatial variances of environmental and ecological characteristics in the Zhujiang River（Pearl River） Estuary and adjacent waters（ZREAW） in the South China Sea. The PCA result shows that the ZREAW can be divided into different zones according to the principal components and geographical locations of the study stations,and indicates that there are distinct regional variances on environmental features and the corresponding phytoplankton biomass and community structures among different areas. The spatial distribution of ecological features was implied to be influenced by various degrees of the different water resources,such as the Pearl River discharges,the coastal current and the oceanic water from the South China Sea. The variation of the biomass maximum zone and the complex impacts on the spatial distributions of phytoplankton biomass and production were also evaluated.
基金supported by the National Natural Science Foundation of China(Nos.41003049,41163006)the Inner Mongolia Natural Science Foundation(No.2015MS0404)
文摘The chemistry of sedimentary organic phosphorus（OP） and its fraction distribution in sediments are greatly influenced by environmental conditions such as terrestrial inputs and runoffs. The linkage of OP with environmental conditions was analyzed on the basis of OP spatial and historical distributions in lake sediments. The redundancy analysis and OP spatial distribution results suggested that both Na OH-OP（OP extracted by Na OH） and Re-OP（residual OP） in surface sediments from the selected 13 lakes reflected the gradient effects of environmental conditions and the autochthonous and/or allochthonous inputs driven by latitude zonality in China. The lake level and salinity of Lake Hulun and the runoff and precipitation of its drainage basin were reconstructed on the basis of the geochemistry index. This work showed that a gradient in weather conditions presented by the latitude zonality in China impacts the OP accumulation through multiple drivers and in many ways.The drivers are mainly precipitation and temperature, governing organic matter（OM）production, degradation rate and transportation in the watershed. Over a long temporal dimension（4000 years）, the vertical distributions of Re-OP and Na OH-OP based on a dated sediment profile from HLH were largely regulated by the autochthonous and/or allochthonous inputs, which depended on the environmental and climate conditions and anthropogenic activities in the drainage basin. This work provides useful environmental geochemistry information to understand the inherent linkage of OP fractionation with environmental conditions and lake evolution.
基金the National Basic Research Program of China (973-2015CB150400)the National Institute of Food and Agriculture (ALA014-1-16016)U.S. Department of Agriculture,Hatch project under ALA014-1-16016
文摘Accurate leaf area simulation is critical for the performance of crop growth models. Area of fully expanded individual leaves of maize hybrids released before 1995 (defined as old hybrids) has been simulated using a bell-shaped function (BSF) and the relationship between its parameters and total leaf number (TLNO). However, modern high-yielding maize hybrids show different canopy architectures. The function parameters calibrated for old hybrids will not accurately represent modern hybrids. In this study, we evaluated these functions using a dataset including old and modern hybrids that have been widely planted in China in recent years. Maximum individual leaf area (Y_0) and corresponding leaf position (X_0) were not predicted well by TLNO (R^2= 0.56 and R^2= 0.70) for modern hybrids. Using recalibrated shape parameters a and b with values of Y_0 and X_0 for modern hybrids, the BSF accurately predicted individual leaf area (R^2= 0.95–0.99) and total leaf area of modern hybrids (R^2= 0.98). The results show that the BSF is still a robust way to predict the fully expanded leaf area of maize when parameters a and b are modified and Y_0 and X_0 are fitted. Breeding programs have led to increases in TLNO of maize but have not altered Y_0 and X_0, reducing the correlation between Y_0, X_0, and TLNO. For modern hybrids, the values of Y_0 and X_0 are hybrid-specific. Modern hybrids tend to have less-negative values of parameter a and more-positive values of parameter b in the leaf profile. Growth conditions, such as plant density and environmental conditions, also affect the fully expanded leaf area but were not considered in the original published equations. Thus, further research is needed to accurately estimate values of Y_0 and X_0 of individual modern hybrids to improve simulation of maize leaf area in crop growth models.
