Rainfall provides essential water resource for vegetation growth and acts as driving force for hydrologic process,bedrock weathering and nutrient cycle in the steep hilly catchment.But the effects of rainfall features...Rainfall provides essential water resource for vegetation growth and acts as driving force for hydrologic process,bedrock weathering and nutrient cycle in the steep hilly catchment.But the effects of rainfall features,vegetation types,topography,and also their interactions on soil water movement and soil moisture dynamics are inadequately quantified.During the coupled wet and dry periods of the year 2018 to 2019,time-series soil moisture was monitored with 5-min interval resolution in a hilly catchment of the Three Gorges Reservoir Area in China.Three hillslopes covered with evergreen forest(EG),secondary deciduous forest mixed with shrubs(SDFS)and deforested pasture(DP)were selected,and two monitoring sites with five detected depths were established at upslope and downslope position,respectively.Several parameters expressing soil moisture response to rainfall event were evaluated,including wetting depth,cumulative rainfall amount and lag time before initial response,maximum increase of soil water storage,and transform ratio of rainwater to soil water.The results indicated that rainfall amount is the dominant rainfall variable controlling soil moisture response to rainfall event.No soil moisture response occurred when rainfall amounts was<8 mm,and all the deepest monitoring sensors detected soil moisture increase when total rainfall amounts was>30 mm.In the wet period,the cumulative rainfall amount to trigger surface soil moisture response in EG-up site was significantly higher than in other five sites.However,no significant difference in cumulative rainfall amount to trigger soil moisture response was observed among all study sites in dry period.Vegetation canopy interception reduced the transform ratio of rainwater to soil water,with a higher reduction in vegetation growth period than in other period.Also,interception of vegetation canopy resulted in a larger accumulated rainfall amount and a longer lag time for initiating soil moisture response to rainfall.Generally,average cumulative rainfall amount for initiating soil moisture response during dry period of all sites(3.5-5.6 mm)were less than during wet period(5.7-19.7 mm).Forests captured more infiltration water compared with deforested pasture,showing the larger increments of both soil water storage for the whole soil profile and volumetric soil water content at 10 cm depth on two forest slopes.Topography dominated soil subsurface flow,proven by the evidences that less rainfall amount and less time was needed to trigger soil moisture response and also larger accumulated soil water storage increment in downslope site than in corresponding upslope site during heavy rainfall events.展开更多
This study examines the impact of cash crop cultivation on household income and migration decisions,using survey data collected from low-income regions in China.Given farmers decide themselves whether to cultivate cas...This study examines the impact of cash crop cultivation on household income and migration decisions,using survey data collected from low-income regions in China.Given farmers decide themselves whether to cultivate cash crops,an endogenous treatment regression model that accounts for potential selection bias issue is used to analyze the data.The empirical results show that cash crop cultivation exerts a positive and statistically significant impact on household income,but it does not affect household migration decisions significantly.The disaggregated analyses reveal that cash crop cultivation significantly increases farm income but decreases off-farm income.展开更多
Tree peony is a unique traditional f lower in China,with large,fragrant,and colorful f lowers.However,a relatively short and concentrated f lowering period limits the applications and production of tree peony.A genome...Tree peony is a unique traditional f lower in China,with large,fragrant,and colorful f lowers.However,a relatively short and concentrated f lowering period limits the applications and production of tree peony.A genome-wide association study(GWAS)was conducted to accelerate molecular breeding for the improvement of f lowering phenology traits and ornamental phenotypes in tree peony.A diverse panel of 451 tree peony accessions was phenotyped for 23 f lowering phenology traits and 4 f loral agronomic traits over 3 years.Genotyping by sequencing(GBS)was used to obtain a large number of genome-wide single-nucleotide polymorphisms(SNPs)(107050)for the panel genotypes,and 1047 candidate genes were identified by association mapping.Eighty-two related genes were observed during at least 2 years for f lowering,and seven SNPs repeatedly identified for multiple f lowering phenology traits over multiple years were highly significantly associated with five genes known to regulate f lowering time.We validated the temporal expression profiles of these candidate genes and highlighted their possible roles in the regulation of f lower bud differentiation and f lowering time in tree peony.This study shows that GWAS based on GBS can be used to identify the genetic determinants of complex traits in tree peony.The results expand our understanding of f lowering time control in perennial woody plants.Identification of markers closely related to these f lowering phenology traits can be used in tree peony breeding programs for important agronomic traits.展开更多
Arsenic(As)is a known carcinogen and naturally occurring semi-metal in soils and in the Earth's crust.Contamination of soils and water with As poses a serious threat to millions of people worldwide due to its heal...Arsenic(As)is a known carcinogen and naturally occurring semi-metal in soils and in the Earth's crust.Contamination of soils and water with As poses a serious threat to millions of people worldwide due to its health hazards and toxicological properties.Hence,devising novel and efficient methods for remediation of contaminated areas has attracted a great deal of interest across the globe.In this study,we investigated the usefulness of synthetic birnessite,goethite,hexadecylpyridinium chloride-modified montmorillonite(HDPC-M),hexadecylpyridinium bromide-modified zeolite(HDPB-Z),and lanthanum(La)-doped magnetic biochar produced from eucalyptus bark(La-Euchar)as adsorbents at 10%dosage for As stabilization in a soil spiked with 1000 mg kg^(-1)As.The effectiveness of the above adsorbents in As immobilization in soil was assessed using single-step extractions with 2 mol L^(-1)HNO_(3)and deionized water,the simplified bioaccessibility extraction test(SBET)method,and sequential extraction with the modified Community Bureau of Reference(BCR)method.Application of the adsorbents shifted the exchangeable fraction of As to more recalcitrant fractions and dramatically reduced the exchangeable fraction by 6%-99%and the extractable amounts with HNO_(3),deionized water,and SBET method by 30%-92%,17%-95%,and 12%-90%,respectively,compared to the unamended control.The immobilizing effects of adsorbents on As decreased in the sequence of birnessite>La-Euchar>goethite>HDPB-Z>HDPC-M.Birnessite exhibited great affinity for As and drastically reduced As extractability by more than 90%in all single extractions.The results revealed that HDPC-M,HDPB-Z,La-Euchar,birnessite,and goethite are promising immobilizing agents for in situ stabilization of As in terrestrial environments.展开更多
HoneySweet’plum(Prunus domestica)is resistant to Plum pox potyvirus,through an RNAi-triggered mechanism.Determining the precise nature of the transgene insertion event has been complicated due to the hexaploid genome...HoneySweet’plum(Prunus domestica)is resistant to Plum pox potyvirus,through an RNAi-triggered mechanism.Determining the precise nature of the transgene insertion event has been complicated due to the hexaploid genome of plum.DNA blots previously indicated an unintended hairpin arrangement of the Plum pox potyvirus coat protein gene as well as a multicopy insertion event.To confirm the transgene arrangement of the insertion event,‘HoneySweet’DNA was subjected to whole genome sequencing using Illumina short-read technology.Results indicated two different insertion events,one containing seven partial copies flanked by putative plum DNA sequence and a second with the predicted inverted repeat of the coat protein gene driven by a double 35S promoter on each side,flanked by plum DNA.To determine the locations of the two transgene insertions,a phased plum genome assembly was developed from the commercial plum‘Improved French’.A subset of the scaffolds(2447)that were>10 kb in length and representing,>95%of the genome were annotated and used for alignment against the‘HoneySweet’transgene reads.Four of eight matching scaffolds spanned both insertion sites ranging from 157,704 to 654,883 bp apart,however we were unable to identify which scaffold(s)represented the actual location of the insertion sites due to potential sequence differences between the two plum cultivars.Regardless,there was no evidence of any gene(s)being interrupted as a result of the insertions.Furthermore,RNA-seq data verified that the insertions created no new transcriptional units and no dramatic expression changes of neighboring genes.展开更多
The efficacy of limestone sand and pelletized lime for remediation of soil acidity was compared in order to determine if limestone sand was a more cost-effective alternative to pelletized lime. Between fall of 2002 an...The efficacy of limestone sand and pelletized lime for remediation of soil acidity was compared in order to determine if limestone sand was a more cost-effective alternative to pelletized lime. Between fall of 2002 and spring 2003, two forested sites in Pennsylvania were clear cut and fenced. Pelletized lime and limestone sand were applied to separate 400-m2 plots within the sites at rates of 2170 kg·ha-1 and 4335 kg·ha-1, respectively. Two additional 400-m2 plots were used as controls. A paired before-after control-impact study design was used to assess changes in soil, soil solution, vegetation and biomass after lime application. Soil samples were collected from the Oi, Oe + Oa, and A horizons before and after lime application. Woody and herbaceous vegetation was harvested from 1-m2 sub-plots before and after liming and bi-weekly soil solution samples were collected for six months following lime application. Analysis of variance procedures were used to compare changes in the treatment plots over time. Changes in soil chemistry following lime application were comparable on the limestone sand and pelletized lime plots. There was a significant increase in exchangeable Mg and Mg saturation in the Oe + Oa horizon on all of the lime treatment plots relative to controls, but a greater percentage of applied Ca and Mg was exchangeable in the O-horizon in pelletized lime plots nine months after liming. Plant biomass did not increase on the lime treatment plots relative to the control one year post treatment. The majority of applied Ca and Mg from pelletized lime and limestone sand remained in the litter layer, with little movement into the A-horizon after one growing season. These results indicated that the application of limestone sand at two times the rate of pelletized lime produced comparable changes in soil and soil solution chemistry at a fraction of the cost.展开更多
With the rise of urbanization, change in lifestyles, and food habits, the amount of Municipal Solid Waste (MSW) has been rapidly increasing with the composition constantly changing. Landfilling is the common approach ...With the rise of urbanization, change in lifestyles, and food habits, the amount of Municipal Solid Waste (MSW) has been rapidly increasing with the composition constantly changing. Landfilling is the common approach for waste management in Kuwait, and around 90% of municipal wastes are disposed in landfill sites. Therefore, this study focused on the integration of different methods for the process of allocating optimum sites for MSW landfills, in four main stages. The first stage focused on utilizing the gap analysis method for the identification of effective criteria for landfill site selection, by comparing the criteria in Kuwait with the World Bank guidelines, US EPA, and Australia EPA, to suggest the best criteria for landfill site selection. These criteria were applied in the second and third stages to determine suitable locations for landfill sites using the Geographical Information System (GIS). In the last stage, the suitable areas were evaluated by studying the socioeconomic aspects such as distance to waste generation center, the proximity of existing roads, and lifespan to select optimum locations for landfilling. The results indicated that only one site with a total area of 12 km2 was considered optimum for MSW landfill sites in Kuwait. Therefore, moderate suitability areas were indicated to support and provide decision makers with more options. The moderately suitable sites are also suitable for landfilling, but they need to be designed carefully in order to avoid negative impacts on the environment and human health. Therefore, we conclude that there is an urgent need to apply the integrated waste management system in Kuwait, as well as to develop a long-term strategic plan.展开更多
Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, s...Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure spectroscopy, and its performances for removal of Pb^2＋ and Cr^3＋ from aqueous solutions were investigated. Co doping has a negligible effect on the structure and morphology of cryptomelane but increases the specific surface area and Mn average oxidation state. Mn and Co K-edge extended X-ray absorption fine structure spectroscopy（EXAFS） analysis shows that Co barely affects the atomic coordination environments of Mn, and distances of edge- and corner-sharing Co–Me（Me_Co, Mn） pairs are shorter than those of the corresponding Mn–Me pairs, implying the replacement of framework Mn（III） by Co（III）. These Co-doped cryptomelanes can quickly oxidize Cr3＋to be HCr O4-and remove 45%–66% of the total Cr in the reaction systems by adsorption and fixation, and they have enhanced Pb2＋adsorption capacities. Thus these materials are promising adsorbents for heavy metal remediation. The results demonstrate the design and modification of environmental friendly Mn oxide materials and can help us understand the interaction mechanisms of transition metals with Mn oxides.展开更多
Zinc-ion hybrid supercapacitors(ZHSCs)have enormous potential for future applications in electric vehi-cles,portable/wearable electronic gadgets,etc.However,to accelerate ZHSC technology towards market applications,it...Zinc-ion hybrid supercapacitors(ZHSCs)have enormous potential for future applications in electric vehi-cles,portable/wearable electronic gadgets,etc.However,to accelerate ZHSC technology towards market applications,it is necessary to overcome research challenges such as Zn dendrites,low Zn utilization,and all-climate adaptability,as well as to streamline the device assembly process.In this study,we propose a new strategy for the facile construction of ZHSC via two porous carbon fabrics and a Zn plating solution.The cathode and current collector of the device are both porous graphitized carbon fabric(PGCF)pre-pared by high-temperature activation of K2 FeO_(4),and the Li_(2)ZnCl_(4)·9H_(2)O electrolyte is verified to possess excellent Zn plating/stripping efficiency and inhibition of Zn dendrite growth in a Zn-Zn symmetric cell model.As a result,the assembled ZHSC has the maximum energy density of 2.02 mWh cm^(−2)and the highest power density of 11.47 mW cm^(−2),and it can operate for 30,000 cycles without capacity degrada-tion.Furthermore,the destruction of the hydrogen bonding network by the high concentration of Cl−at low temperatures endows it with low freezing point properties and excellent ionic activity at low tem-peratures.The device also operated reliably at-60℃,with a maximum areal capacity of 1.15 mAh cm^(−2).This research offers new findings and insights for the development of high-performance ultra-cryogenic ZHSC devices.展开更多
Prunus domestica commonly known as European plum is a hexaploid fruit tree species cultivated around the world.Locally it is used for fresh consumption,in jams or jellies,and the production of spirits while commercial...Prunus domestica commonly known as European plum is a hexaploid fruit tree species cultivated around the world.Locally it is used for fresh consumption,in jams or jellies,and the production of spirits while commercially the fruit is primarily sold dried(prunes).Despite its agricultural importance and long history of cultivation,many questions remain about the origin of this species,the relationships among its many pomological types,and its underlying genetics.Here,we used a sequence-based genotyping approach to characterize worldwide plum germplasm including the potential progenitor Eurasian plum species.Analysis of 405 DNA samples established a set of four clades consistent with the pomological groups Greengages,Mirabelles,European plums,and d’Agen(French)prune plums.A number of cultivars from each clade were identified as likely clonal selections,particularly among the“French”type prune germplasm that is widely cultivated today.Overall,there was relatively low genetic diversity across all cultivated plums suggesting they have been largely inbred and/or derived from a limited number of founders.The results agree with P.domestica having originated as an interspecific hybrid of a diploid P.cerasifera and a tetraploid P.spinosa that itself may have been an interspecific hybrid of P.cerasifera and an unknown Eurasian plum species.The low genetic diversity and lack of true wild-types coupled with the known cultivation history of Eurasian plums imply that P.domestica may have been a product of inter-specific cross breeding and artificial selection by early agrarian Eurasian societies.展开更多
Managing mature Douglas-fir[Pseudotsuga menziesii(Mirb.)Franco]stands to emulate the structural complexity of natural old-growth forest requires identifying structural targets at the sub-stand level at which neighborh...Managing mature Douglas-fir[Pseudotsuga menziesii(Mirb.)Franco]stands to emulate the structural complexity of natural old-growth forest requires identifying structural targets at the sub-stand level at which neighborhood dynamics and patchy disturbance shape structure.We therefore sought to describe the archetypal shapes of predominant sub-stand diameter distribution types(DDTs)observed in natural tree neighborhoods in stands comprising a chronosequence(ca.120-450+yrs)encompassing mature,vertical diversification,and horizontal diversification development stages.The ten 1.0 ha stands are located in the southcentral Oregon Cascades,USA.Building on the known spatial position of each tree,natural tree neighborhoods were identified using the floating neighborhood approach based on spatial tessellation connecting neighboring trees at the first-(mean 61 m2)through fifth-(mean 2058 m2)order scales.Cluster analysis was then used to objectively identify the most predominant DDTs among the relative tree size distributions observed in the trans-scale neighborhoods within each stand.Repeated measures regression was used to classify each DDT to one of six observed archetypal shapes:negative exponential,unimodal,rotated sigmoid,bimodal,concave,or multi-modal.Only three of the 81 observed DDTs deviated by<10%from the stand average,while every stand had at least one DDT that deviated by>50%(maximum 83%).Within each stand,five to ten predominant DDTs were observed,which deviated from the stand average by 30-48%and were characterized by two to five different archetypal shapes.Consequently,in some stands the majority of tree neighborhoods were best characterized by a different shape from that assigned at the stand level.Deviation from the stand average increased from the youngest stand in the mature development stage through the middle stands in the vertical diversification stage to the oldest stands in the horizontal diversification stage.The complexity of DDT shapes tended to increase along the chronosequence(from negative exponential and uniform toward concave and multi-modal),with shape richness highest mid-sequence and evenness peaking in the oldest stands.The high diversity of sub-stand structural complexity reduces the utility of standlevel diameter distributions as old-growth restoration targets.However,the presence in early-sequence stands of sub-stand diameter distributions common to later-sequence stands may facilitate active management at the neighborhood level to promote future old-growth condition.Restoration of substand diameter structures would likely require combining spatial perspectives,such as by augmenting tree-level croptree management with diameter distribution targets for the resulting tree neighborhoods.展开更多
Soil nitrogen(N) is critical to ecosystem services and environmental quality. Hotspots of soil N in areas with high soil moisture have been widely studied, however, their spatial distribution and their linkage with so...Soil nitrogen(N) is critical to ecosystem services and environmental quality. Hotspots of soil N in areas with high soil moisture have been widely studied, however, their spatial distribution and their linkage with soil N variation have seldom been examined at a catchment scale in areas with low soil water content. We investigated the spatial variation of soil N and its hotspots in a mixed land cover catchment on the Chinese Loess Plateau and used multiple statistical methods to evaluate the effects of the critical environmental factors on soil N variation and potential hotspots. The results demonstrated that land cover, soil moisture, elevation, plan curvature and flow accumulation were the dominant factors affecting the spatial variation of soil nitrate(NN), while land cover and slope aspect were the most important factors impacting the spatial distribution of soil ammonium(AN) and total nitrogen(TN). In the studied catchment, the forestland, gully land and grassland were found to be the potential hotspots of soil NN, AN and TN accumulation, respectively. We concluded that land cover and slope aspect could be proxies to determine the potential hotspots of soil N at the catchment scale. Overall, land cover was the most important factor that resulted in the spatial variations of soil N. The findings may help us to better understand the environmental factors affecting soil N hotspots and their spatial variation at the catchment scale in terrestrial ecosystems.展开更多
Marine Isotope Stages(MIS) 9 has been proposed as an analog for the present warm period. However, detailed studies of this geological time period are rare in loess-paleosol sequence. In the Chinese Loess Plateau(CLP),...Marine Isotope Stages(MIS) 9 has been proposed as an analog for the present warm period. However, detailed studies of this geological time period are rare in loess-paleosol sequence. In the Chinese Loess Plateau(CLP), the corresponding stratum is the third paleosol layer(S3). Here, we report the terrestrial reconstruction of climatic fluctuations during MIS 9 by analyzing the paleo-climate indexes of S3 with high sampling density. Our results showed that:(1) During the period of MIS 9, the main climatic sub-cycle was 29 ka;(2) MIS 9 could be divided into five sections, MIS 9a, 9b, 9c, 9d, and 9e. Among them, MIS 9a, 9c, and 9e were warm stages, while MIS 9b and 9d were cool intervals;and 3) There were also three swift warm-wet events and one cool-dry event, which occurred around 332 –331, 324–323, 311–310, and 331–329 ka BP, respectively. The overall trend of paleo-climate fluctuation correlated approximately with SPECMAP, LR04 stack and Iberian margin deep-sea cores. This study suggested that the paleosol records in the southern margin of the CLP have global significance and contain more detailed climatic signals than marine deposits.展开更多
This paper proposes a resampling simulator that will calculate probabilities of detecting invasive species infesting hosts that occur in large numbers. Different methods were examined to determine the bias of observed...This paper proposes a resampling simulator that will calculate probabilities of detecting invasive species infesting hosts that occur in large numbers. Different methods were examined to determine the bias of observed cumulative distribution functions (c.d.f.s), generated from prototype resampling simulators. One involved seeing if they matched theoretical c.d.f.s, which were generated using formulae for calculating the probability of the union of many events (union formulae), which are known to be correct. Others involved assessing the bias of observed c.d.f.s, generated from using prototype resampling simulators operating on much larger simulated populations, when computation of theoretical c.d.f.s from the union formulae was not practical. Examples are given for using the proposed resampling simulator for detecting an invasive insect pest within the context of an invasive species management system.展开更多
基金National Natural Science Foundation of China,No.41771261,No.41601215Hubei Province Natural Science Foundation of China,No.2015CFA141,No.2016CFA027,No.2019CFB766Fundamental Research Funds for the Central Universities,No.CCNUI8QN002,No.CCNUI9TS001。
文摘Rainfall provides essential water resource for vegetation growth and acts as driving force for hydrologic process,bedrock weathering and nutrient cycle in the steep hilly catchment.But the effects of rainfall features,vegetation types,topography,and also their interactions on soil water movement and soil moisture dynamics are inadequately quantified.During the coupled wet and dry periods of the year 2018 to 2019,time-series soil moisture was monitored with 5-min interval resolution in a hilly catchment of the Three Gorges Reservoir Area in China.Three hillslopes covered with evergreen forest(EG),secondary deciduous forest mixed with shrubs(SDFS)and deforested pasture(DP)were selected,and two monitoring sites with five detected depths were established at upslope and downslope position,respectively.Several parameters expressing soil moisture response to rainfall event were evaluated,including wetting depth,cumulative rainfall amount and lag time before initial response,maximum increase of soil water storage,and transform ratio of rainwater to soil water.The results indicated that rainfall amount is the dominant rainfall variable controlling soil moisture response to rainfall event.No soil moisture response occurred when rainfall amounts was<8 mm,and all the deepest monitoring sensors detected soil moisture increase when total rainfall amounts was>30 mm.In the wet period,the cumulative rainfall amount to trigger surface soil moisture response in EG-up site was significantly higher than in other five sites.However,no significant difference in cumulative rainfall amount to trigger soil moisture response was observed among all study sites in dry period.Vegetation canopy interception reduced the transform ratio of rainwater to soil water,with a higher reduction in vegetation growth period than in other period.Also,interception of vegetation canopy resulted in a larger accumulated rainfall amount and a longer lag time for initiating soil moisture response to rainfall.Generally,average cumulative rainfall amount for initiating soil moisture response during dry period of all sites(3.5-5.6 mm)were less than during wet period(5.7-19.7 mm).Forests captured more infiltration water compared with deforested pasture,showing the larger increments of both soil water storage for the whole soil profile and volumetric soil water content at 10 cm depth on two forest slopes.Topography dominated soil subsurface flow,proven by the evidences that less rainfall amount and less time was needed to trigger soil moisture response and also larger accumulated soil water storage increment in downslope site than in corresponding upslope site during heavy rainfall events.
基金Supported by the Humanities and Social Science Research Fund of the Ministry of Education of China(19YJC790063)the Natural Science Foundation of Fujian,China(2017J05112)the Social Science Foundation of Fujian,China(FJ2017C076).
文摘This study examines the impact of cash crop cultivation on household income and migration decisions,using survey data collected from low-income regions in China.Given farmers decide themselves whether to cultivate cash crops,an endogenous treatment regression model that accounts for potential selection bias issue is used to analyze the data.The empirical results show that cash crop cultivation exerts a positive and statistically significant impact on household income,but it does not affect household migration decisions significantly.The disaggregated analyses reveal that cash crop cultivation significantly increases farm income but decreases off-farm income.
基金supported by the National Natural Science Foundation of China(U1804233)the Innovation Scientists and Technicians Troop Construction Projects of Henan Province(202101510003)the Outstanding Youth Fund of the Natural Science Foundation of Henan Province(202300410119).
文摘Tree peony is a unique traditional f lower in China,with large,fragrant,and colorful f lowers.However,a relatively short and concentrated f lowering period limits the applications and production of tree peony.A genome-wide association study(GWAS)was conducted to accelerate molecular breeding for the improvement of f lowering phenology traits and ornamental phenotypes in tree peony.A diverse panel of 451 tree peony accessions was phenotyped for 23 f lowering phenology traits and 4 f loral agronomic traits over 3 years.Genotyping by sequencing(GBS)was used to obtain a large number of genome-wide single-nucleotide polymorphisms(SNPs)(107050)for the panel genotypes,and 1047 candidate genes were identified by association mapping.Eighty-two related genes were observed during at least 2 years for f lowering,and seven SNPs repeatedly identified for multiple f lowering phenology traits over multiple years were highly significantly associated with five genes known to regulate f lowering time.We validated the temporal expression profiles of these candidate genes and highlighted their possible roles in the regulation of f lower bud differentiation and f lowering time in tree peony.This study shows that GWAS based on GBS can be used to identify the genetic determinants of complex traits in tree peony.The results expand our understanding of f lowering time control in perennial woody plants.Identification of markers closely related to these f lowering phenology traits can be used in tree peony breeding programs for important agronomic traits.
文摘Arsenic(As)is a known carcinogen and naturally occurring semi-metal in soils and in the Earth's crust.Contamination of soils and water with As poses a serious threat to millions of people worldwide due to its health hazards and toxicological properties.Hence,devising novel and efficient methods for remediation of contaminated areas has attracted a great deal of interest across the globe.In this study,we investigated the usefulness of synthetic birnessite,goethite,hexadecylpyridinium chloride-modified montmorillonite(HDPC-M),hexadecylpyridinium bromide-modified zeolite(HDPB-Z),and lanthanum(La)-doped magnetic biochar produced from eucalyptus bark(La-Euchar)as adsorbents at 10%dosage for As stabilization in a soil spiked with 1000 mg kg^(-1)As.The effectiveness of the above adsorbents in As immobilization in soil was assessed using single-step extractions with 2 mol L^(-1)HNO_(3)and deionized water,the simplified bioaccessibility extraction test(SBET)method,and sequential extraction with the modified Community Bureau of Reference(BCR)method.Application of the adsorbents shifted the exchangeable fraction of As to more recalcitrant fractions and dramatically reduced the exchangeable fraction by 6%-99%and the extractable amounts with HNO_(3),deionized water,and SBET method by 30%-92%,17%-95%,and 12%-90%,respectively,compared to the unamended control.The immobilizing effects of adsorbents on As decreased in the sequence of birnessite>La-Euchar>goethite>HDPB-Z>HDPC-M.Birnessite exhibited great affinity for As and drastically reduced As extractability by more than 90%in all single extractions.The results revealed that HDPC-M,HDPB-Z,La-Euchar,birnessite,and goethite are promising immobilizing agents for in situ stabilization of As in terrestrial environments.
文摘HoneySweet’plum(Prunus domestica)is resistant to Plum pox potyvirus,through an RNAi-triggered mechanism.Determining the precise nature of the transgene insertion event has been complicated due to the hexaploid genome of plum.DNA blots previously indicated an unintended hairpin arrangement of the Plum pox potyvirus coat protein gene as well as a multicopy insertion event.To confirm the transgene arrangement of the insertion event,‘HoneySweet’DNA was subjected to whole genome sequencing using Illumina short-read technology.Results indicated two different insertion events,one containing seven partial copies flanked by putative plum DNA sequence and a second with the predicted inverted repeat of the coat protein gene driven by a double 35S promoter on each side,flanked by plum DNA.To determine the locations of the two transgene insertions,a phased plum genome assembly was developed from the commercial plum‘Improved French’.A subset of the scaffolds(2447)that were>10 kb in length and representing,>95%of the genome were annotated and used for alignment against the‘HoneySweet’transgene reads.Four of eight matching scaffolds spanned both insertion sites ranging from 157,704 to 654,883 bp apart,however we were unable to identify which scaffold(s)represented the actual location of the insertion sites due to potential sequence differences between the two plum cultivars.Regardless,there was no evidence of any gene(s)being interrupted as a result of the insertions.Furthermore,RNA-seq data verified that the insertions created no new transcriptional units and no dramatic expression changes of neighboring genes.
文摘The efficacy of limestone sand and pelletized lime for remediation of soil acidity was compared in order to determine if limestone sand was a more cost-effective alternative to pelletized lime. Between fall of 2002 and spring 2003, two forested sites in Pennsylvania were clear cut and fenced. Pelletized lime and limestone sand were applied to separate 400-m2 plots within the sites at rates of 2170 kg·ha-1 and 4335 kg·ha-1, respectively. Two additional 400-m2 plots were used as controls. A paired before-after control-impact study design was used to assess changes in soil, soil solution, vegetation and biomass after lime application. Soil samples were collected from the Oi, Oe + Oa, and A horizons before and after lime application. Woody and herbaceous vegetation was harvested from 1-m2 sub-plots before and after liming and bi-weekly soil solution samples were collected for six months following lime application. Analysis of variance procedures were used to compare changes in the treatment plots over time. Changes in soil chemistry following lime application were comparable on the limestone sand and pelletized lime plots. There was a significant increase in exchangeable Mg and Mg saturation in the Oe + Oa horizon on all of the lime treatment plots relative to controls, but a greater percentage of applied Ca and Mg was exchangeable in the O-horizon in pelletized lime plots nine months after liming. Plant biomass did not increase on the lime treatment plots relative to the control one year post treatment. The majority of applied Ca and Mg from pelletized lime and limestone sand remained in the litter layer, with little movement into the A-horizon after one growing season. These results indicated that the application of limestone sand at two times the rate of pelletized lime produced comparable changes in soil and soil solution chemistry at a fraction of the cost.
文摘With the rise of urbanization, change in lifestyles, and food habits, the amount of Municipal Solid Waste (MSW) has been rapidly increasing with the composition constantly changing. Landfilling is the common approach for waste management in Kuwait, and around 90% of municipal wastes are disposed in landfill sites. Therefore, this study focused on the integration of different methods for the process of allocating optimum sites for MSW landfills, in four main stages. The first stage focused on utilizing the gap analysis method for the identification of effective criteria for landfill site selection, by comparing the criteria in Kuwait with the World Bank guidelines, US EPA, and Australia EPA, to suggest the best criteria for landfill site selection. These criteria were applied in the second and third stages to determine suitable locations for landfill sites using the Geographical Information System (GIS). In the last stage, the suitable areas were evaluated by studying the socioeconomic aspects such as distance to waste generation center, the proximity of existing roads, and lifespan to select optimum locations for landfilling. The results indicated that only one site with a total area of 12 km2 was considered optimum for MSW landfill sites in Kuwait. Therefore, moderate suitability areas were indicated to support and provide decision makers with more options. The moderately suitable sites are also suitable for landfilling, but they need to be designed carefully in order to avoid negative impacts on the environment and human health. Therefore, we conclude that there is an urgent need to apply the integrated waste management system in Kuwait, as well as to develop a long-term strategic plan.
基金supported by the National Natural Science Foundation of China (Nos.41271253 and 41401250)the Huazhong Agricultural University Doctoral Start-up Fund (Grant 52902-0900206162)
文摘Cryptomelane is a reactive Mn oxide and has been used in removal of heavy metal from wastewaters. Co-doped cryptomelane was synthesized by refluxing at ambient pressure and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and extended X-ray absorption fine structure spectroscopy, and its performances for removal of Pb^2＋ and Cr^3＋ from aqueous solutions were investigated. Co doping has a negligible effect on the structure and morphology of cryptomelane but increases the specific surface area and Mn average oxidation state. Mn and Co K-edge extended X-ray absorption fine structure spectroscopy（EXAFS） analysis shows that Co barely affects the atomic coordination environments of Mn, and distances of edge- and corner-sharing Co–Me（Me_Co, Mn） pairs are shorter than those of the corresponding Mn–Me pairs, implying the replacement of framework Mn（III） by Co（III）. These Co-doped cryptomelanes can quickly oxidize Cr3＋to be HCr O4-and remove 45%–66% of the total Cr in the reaction systems by adsorption and fixation, and they have enhanced Pb2＋adsorption capacities. Thus these materials are promising adsorbents for heavy metal remediation. The results demonstrate the design and modification of environmental friendly Mn oxide materials and can help us understand the interaction mechanisms of transition metals with Mn oxides.
基金supported by the National Natural Science Foun-dation of China(Grant No.51902041).
文摘Zinc-ion hybrid supercapacitors(ZHSCs)have enormous potential for future applications in electric vehi-cles,portable/wearable electronic gadgets,etc.However,to accelerate ZHSC technology towards market applications,it is necessary to overcome research challenges such as Zn dendrites,low Zn utilization,and all-climate adaptability,as well as to streamline the device assembly process.In this study,we propose a new strategy for the facile construction of ZHSC via two porous carbon fabrics and a Zn plating solution.The cathode and current collector of the device are both porous graphitized carbon fabric(PGCF)pre-pared by high-temperature activation of K2 FeO_(4),and the Li_(2)ZnCl_(4)·9H_(2)O electrolyte is verified to possess excellent Zn plating/stripping efficiency and inhibition of Zn dendrite growth in a Zn-Zn symmetric cell model.As a result,the assembled ZHSC has the maximum energy density of 2.02 mWh cm^(−2)and the highest power density of 11.47 mW cm^(−2),and it can operate for 30,000 cycles without capacity degrada-tion.Furthermore,the destruction of the hydrogen bonding network by the high concentration of Cl−at low temperatures endows it with low freezing point properties and excellent ionic activity at low tem-peratures.The device also operated reliably at-60℃,with a maximum areal capacity of 1.15 mAh cm^(−2).This research offers new findings and insights for the development of high-performance ultra-cryogenic ZHSC devices.
基金supported in part by a National Institute of General Medical Sciences Grant:P20GM109094 and funding from the California Dried Plum Board.
文摘Prunus domestica commonly known as European plum is a hexaploid fruit tree species cultivated around the world.Locally it is used for fresh consumption,in jams or jellies,and the production of spirits while commercially the fruit is primarily sold dried(prunes).Despite its agricultural importance and long history of cultivation,many questions remain about the origin of this species,the relationships among its many pomological types,and its underlying genetics.Here,we used a sequence-based genotyping approach to characterize worldwide plum germplasm including the potential progenitor Eurasian plum species.Analysis of 405 DNA samples established a set of four clades consistent with the pomological groups Greengages,Mirabelles,European plums,and d’Agen(French)prune plums.A number of cultivars from each clade were identified as likely clonal selections,particularly among the“French”type prune germplasm that is widely cultivated today.Overall,there was relatively low genetic diversity across all cultivated plums suggesting they have been largely inbred and/or derived from a limited number of founders.The results agree with P.domestica having originated as an interspecific hybrid of a diploid P.cerasifera and a tetraploid P.spinosa that itself may have been an interspecific hybrid of P.cerasifera and an unknown Eurasian plum species.The low genetic diversity and lack of true wild-types coupled with the known cultivation history of Eurasian plums imply that P.domestica may have been a product of inter-specific cross breeding and artificial selection by early agrarian Eurasian societies.
基金funded by USDA National Institute of Food and Agriculture Hatch Appropriations[#PEN04639,Accession#1015105,EZ]。
文摘Managing mature Douglas-fir[Pseudotsuga menziesii(Mirb.)Franco]stands to emulate the structural complexity of natural old-growth forest requires identifying structural targets at the sub-stand level at which neighborhood dynamics and patchy disturbance shape structure.We therefore sought to describe the archetypal shapes of predominant sub-stand diameter distribution types(DDTs)observed in natural tree neighborhoods in stands comprising a chronosequence(ca.120-450+yrs)encompassing mature,vertical diversification,and horizontal diversification development stages.The ten 1.0 ha stands are located in the southcentral Oregon Cascades,USA.Building on the known spatial position of each tree,natural tree neighborhoods were identified using the floating neighborhood approach based on spatial tessellation connecting neighboring trees at the first-(mean 61 m2)through fifth-(mean 2058 m2)order scales.Cluster analysis was then used to objectively identify the most predominant DDTs among the relative tree size distributions observed in the trans-scale neighborhoods within each stand.Repeated measures regression was used to classify each DDT to one of six observed archetypal shapes:negative exponential,unimodal,rotated sigmoid,bimodal,concave,or multi-modal.Only three of the 81 observed DDTs deviated by<10%from the stand average,while every stand had at least one DDT that deviated by>50%(maximum 83%).Within each stand,five to ten predominant DDTs were observed,which deviated from the stand average by 30-48%and were characterized by two to five different archetypal shapes.Consequently,in some stands the majority of tree neighborhoods were best characterized by a different shape from that assigned at the stand level.Deviation from the stand average increased from the youngest stand in the mature development stage through the middle stands in the vertical diversification stage to the oldest stands in the horizontal diversification stage.The complexity of DDT shapes tended to increase along the chronosequence(from negative exponential and uniform toward concave and multi-modal),with shape richness highest mid-sequence and evenness peaking in the oldest stands.The high diversity of sub-stand structural complexity reduces the utility of standlevel diameter distributions as old-growth restoration targets.However,the presence in early-sequence stands of sub-stand diameter distributions common to later-sequence stands may facilitate active management at the neighborhood level to promote future old-growth condition.Restoration of substand diameter structures would likely require combining spatial perspectives,such as by augmenting tree-level croptree management with diameter distribution targets for the resulting tree neighborhoods.
基金financially supported by the National key research and development program (2017YFD0800502)the National Natural Science Foundation of China (Grant Nos. 41573067, 41790444, 41471189, 31700414)
文摘Soil nitrogen(N) is critical to ecosystem services and environmental quality. Hotspots of soil N in areas with high soil moisture have been widely studied, however, their spatial distribution and their linkage with soil N variation have seldom been examined at a catchment scale in areas with low soil water content. We investigated the spatial variation of soil N and its hotspots in a mixed land cover catchment on the Chinese Loess Plateau and used multiple statistical methods to evaluate the effects of the critical environmental factors on soil N variation and potential hotspots. The results demonstrated that land cover, soil moisture, elevation, plan curvature and flow accumulation were the dominant factors affecting the spatial variation of soil nitrate(NN), while land cover and slope aspect were the most important factors impacting the spatial distribution of soil ammonium(AN) and total nitrogen(TN). In the studied catchment, the forestland, gully land and grassland were found to be the potential hotspots of soil NN, AN and TN accumulation, respectively. We concluded that land cover and slope aspect could be proxies to determine the potential hotspots of soil N at the catchment scale. Overall, land cover was the most important factor that resulted in the spatial variations of soil N. The findings may help us to better understand the environmental factors affecting soil N hotspots and their spatial variation at the catchment scale in terrestrial ecosystems.
基金financially supported by the National Natural Science Foundation of China (No.41701323)the China Scholarship Council (No.201806775033)Financially supported by the self-determined research funds of CCNU from the colleges’ basic research and operation of MOE (No.CCNU20QN033)。
文摘Marine Isotope Stages(MIS) 9 has been proposed as an analog for the present warm period. However, detailed studies of this geological time period are rare in loess-paleosol sequence. In the Chinese Loess Plateau(CLP), the corresponding stratum is the third paleosol layer(S3). Here, we report the terrestrial reconstruction of climatic fluctuations during MIS 9 by analyzing the paleo-climate indexes of S3 with high sampling density. Our results showed that:(1) During the period of MIS 9, the main climatic sub-cycle was 29 ka;(2) MIS 9 could be divided into five sections, MIS 9a, 9b, 9c, 9d, and 9e. Among them, MIS 9a, 9c, and 9e were warm stages, while MIS 9b and 9d were cool intervals;and 3) There were also three swift warm-wet events and one cool-dry event, which occurred around 332 –331, 324–323, 311–310, and 331–329 ka BP, respectively. The overall trend of paleo-climate fluctuation correlated approximately with SPECMAP, LR04 stack and Iberian margin deep-sea cores. This study suggested that the paleosol records in the southern margin of the CLP have global significance and contain more detailed climatic signals than marine deposits.
文摘This paper proposes a resampling simulator that will calculate probabilities of detecting invasive species infesting hosts that occur in large numbers. Different methods were examined to determine the bias of observed cumulative distribution functions (c.d.f.s), generated from prototype resampling simulators. One involved seeing if they matched theoretical c.d.f.s, which were generated using formulae for calculating the probability of the union of many events (union formulae), which are known to be correct. Others involved assessing the bias of observed c.d.f.s, generated from using prototype resampling simulators operating on much larger simulated populations, when computation of theoretical c.d.f.s from the union formulae was not practical. Examples are given for using the proposed resampling simulator for detecting an invasive insect pest within the context of an invasive species management system.
