Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pest...Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.展开更多
Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and developm...Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.展开更多
In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a to...In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a total of 19,126 solar flares were observed regardless the class: 3548 flares in solar cycle 23 (SC23) and 15,668 flares in solar cycle 24 (SC24). Our findings show that the cycle 23 has observed the highest occurrences of M-class and X-class flares, whereas cycle 24 has pointed out a predominance of B-class and C-class flares throughout its different phases. The results indicate that the cycle 23 was magnetically more intense than cycle 24, leading to more powerful solar flares and more frequent geomagnetic storms, capable of generating significant electromagnetic emissions that can affect satellites and GPS signals. The decrease in intense solar flares during cycle 24 compared to cycle 23 reflects an evolution in solar activity patterns over time.展开更多
Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the co...Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the complex and time-consuming nature of traditional sequential laboratory extraction methods for determining the forms of HMs in tailings,a rapid and precise identification approach is urgently required.To address this issue,a general empirical prediction method for HM occurrence was developed using machine learning(ML).The compositional information of the tailings,properties of the HMs,and sequential extraction steps were used as inputs to calculate the percentages of the seven forms of HMs.After the models were tuned and compared,extreme gradient boosting,gradient boosting decision tree,and categorical boosting methods were found to be the top three performing ML models,with the coefficient of determination(R^(2))values on the testing set exceeding 0.859.Feature importance analysis for these three optimal models indicated that electronegativity was the most important factor affecting the occurrence of HMs,with an average feature importance of 0.4522.The subsequent use of stacking as a model integration method enabled the ability of the ML models to predict HM occurrence forms to be further improved,and resulting in an increase of R^(2) to 0.879.Overall,this study developed a robust technique for predicting the occurrence forms in tailings and provides an important reference for the environmental assessment and recycling of tailings.展开更多
Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and m...Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.展开更多
The microscopic occurrence characteristics primarily constrain the enrichment and mobility of shale oil.This study collected the lacustrine shales from the Palaeogene Funing Formation in the Gaoyou Sag, Subei Basin. C...The microscopic occurrence characteristics primarily constrain the enrichment and mobility of shale oil.This study collected the lacustrine shales from the Palaeogene Funing Formation in the Gaoyou Sag, Subei Basin. Conventional and multistage Rock-Eval, scanning electron microscopy, and nuclear magnetic resonance(NMR) T1-T2were performed to analyze the contents and occurrence characteristics of shale oil. Low-temperature nitrogen adsorption-desorption(LTNA/D) experiments were conducted on the shales before and after extraction. The relationships between shale oil occurrence with organic matter and pore structures were then discussed. Predominantly, the shale oil in the Funing Formation is found within fractures, with secondary occurrences in interparticle pores linked to brittle minerals and sizeable intraparticle pores associated with clay minerals. The selected shales can be categorized into two types based on the nitrogen isotherms. Type A shales are characterized by high contents of felsic and calcareous minerals but low clay minerals, with larger TOC and shale oil values. Conversely, Type B shales are marked by abundant clay minerals but diminished TOC and shale oil contents. The lower BET specific surface area(SSA), larger average pore diameter, and simpler pore surfaces and pore structures lead to the Type A shales being more conducive to shale oil enrichment and mobility. Shale oil content is predominantly governed by the abundance of organic matter, while an overabundance of organic matter typically equates to a reduced ratio of free oil and diminished fluidity. The BET SSA, volumes of pores less than 25 and 100 nm at extracted state all correlate negatively with total and adsorbed oil contents but display no correlation with free oil, while they have positive relationships with capillary-bound water.Consequently, pore water is mainly saturated in micropores(<25 nm) and minipores(25-100 nm), as well as adsorbed oil, while free oil, i.e., bound and movable oil, primarily exists in mesopores(100-1000 nm) and macropores(>1000 nm). These findings may enhance the understanding of the microscopic occurrence characteristics of shale oil and will contribute to guide resource estimation and shale oil sweet spot exploitation in the Gaoyou Sag, Subei Basin.展开更多
Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological con...Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological concerns.Dongting Lake represents a vital freshwater lake in China,and its ecosystem health directly affects regional ecological balance and people’s livelihoods.This study systematically investigated the occurrence characteristics and ecological risks of NEOs in water bodies and sediments across the Dongting Lake basin.Based on surface water and sediment samples collected from 26 representative sampling sites,this study quantified nine NEOs using liquid chromatography triple quadrupole mass spectrometry.Furthermore,it assessed ecological risks posed by the NEOs using the risk quotient(RQ)method and fugacity modeling.The results revealed the presence of six NEOs in the water bodies:imidacloprid(IMI),acetamiprid(ACE),clothianidin(CLO),thiamethoxam(THIA),flonicamid(FLO),and dinotefuran(DIN).The total concentrations of these six NEOs averaged 275.11 ng/L.Five predominant NEOs(i.e.,IMI,THIA,ACE,CLO,and DIN)were identified in the sediments,with a mean concentration of 0.31 ng/g.The NEO concentrations in the water bodies across the Dongting Lake basin increased in the order of the Xiangjiang,Zishui,Yuanjiang,and Lishui rivers(collectively referred to as the Four Rivers),the mainstream of Dongting Lake,the Xinqiang River,the Miluo River,and the Hudu,Ouchi,and Songzi rivers(collectively referred to as the Three Outlets).Sediments from tributaries progressively accumulate in the lake.The ecological risk assessment identified IMI and DIN as the highest-risk compounds(RQ>1),with high-risk areas concentrated in the mainstream of Dongting Lake and the Ouchi,Miluo,and Hudu rivers.The fugacity model showed that IMI,ACE,and THIA are prone to diffuse from sediments to water bodies in most areas,with fugacity fractions(ff)values of greater than 0.5.In contrast,the mainstream of Dongting Lake acts as a sink of CLO and DIN(ff values:<0.5).Sediments at the lake’s outlet emerge as an important sink of NEOs.Based on the results of this study,it is advisable to strengthen the supervision of NEO applications in agricultural areas and to implement zonal control strategies.These measures will help reduce ecological risks and protect the safety of water ecosystems in the Dongting Lake region.展开更多
Understanding the occurrence state of shale oil is crucial for the effective development of shale oil resources.Although the second member of the Kongdian Formation(Ek2)is a key interval for lacustrine shale oil produ...Understanding the occurrence state of shale oil is crucial for the effective development of shale oil resources.Although the second member of the Kongdian Formation(Ek2)is a key interval for lacustrine shale oil production in the Cangdong Sag,Bohai Bay Basin,the occurrence state and controlling factors of shale oil in this formation remain poorly understood.This study established a multi-step programmed pyrolysis,combined with a light hydrocarbon recovery scheme,to quantitatively characterize the shale oil in different occurrence states.An integrated approach utilizing Rock-Eval pyrolysis,pyrolysis-gas chromatography,and crude oil gas chromatography was employed.Factors influencing the shale oil occurrence state were analyzed from petrology and organic geochemistry perspectives.The study revealed significant variations of shale oil occurrence states within the Ek2,attributed to differences in sedimentary organic matter,mineral compositions,sedimentary structures,and thermal maturity.Felsic laminae are the primary reservoir space for oil in laminated shales,and the frequent interbedding of felsic and organic-rich laminae facilitates the retention of free oil.The contents of free and adsorbed oil are primarily influenced by organic matter content and shale storage capacity,both of which exhibit distinct occurrence patterns.Based on the shale reservoir quality classification using the pyrolysis values of S1-1+S1-2 and(S1-1+S1-2)×100/TOC,the Ek2 shale demonstrates significant exploitation potential,with the first-level reservoirs comprising 66%,second-level reservoirs 11%,and third-level reservoirs 23%.These findings provide new insights into the geological accumulation and production of shale oil.展开更多
Pore structure characteristics,gas content,and micro-scale gas occurrence mechanisms were investigated in the Shan_(2)^(3)sub-member marine-continental transitional shale of the southeastern margin of the Ordos Basin ...Pore structure characteristics,gas content,and micro-scale gas occurrence mechanisms were investigated in the Shan_(2)^(3)sub-member marine-continental transitional shale of the southeastern margin of the Ordos Basin using scanning electron microscope images,lowtemperature N_(2)/CO_(2)adsorption and high-pressure mercury intrusion,methane isothermal adsorption experiments,and CH4-saturated nuclear magnetic resonance(NMR).Two distinct shale types were identified:organic pore-rich shale(Type OP)and microfracture-rich shale(Type M).The Type OP shale exhibited relatively well-developed organic matter pores,while the Type M shale was primarily characterized by a high degree of microfracture development.An experimental method combining methane isothermal adsorption on crushed samples and CH4-saturated NMR of plug samples was proposed to determine the adsorbed gas,free gas,and total gas content under high temperature and pressure conditions.There were four main research findings.(1)Marine-continental transitional shale exhibited substantial total gas content in situ,ranging from 2.58 to 5.73 cm^(3)/g,with an average of 4.35 cm^(3)/g.The adsorbed gas primarily resided in organic matter pores through micropore filling and multilayer adsorption,followed by multilayer adsorption in clay pores.(2)The changes in adsorbed and free pore volumes can be divided into four stages.Pores of<5 nm exclusively contain adsorbed gas,while those of 5-20 nm have a high proportion of adsorbed gas alongside free gas.Pores ranging from 20 to 100 nm have a high proportion of free gas and few adsorbed gas,while pores of>100 nm and microfractures are almost predominantly free gas.(3)The proportion of adsorbed gas in Type OP shale exceeds that in Type M,reaching 66%.(4)Methane adsorbed in Type OP shale demonstrates greater desorption capability,suggesting a potential for enhanced stable production,which finds support in existing production well data.However,it must be emphasized that high-gas-bearing intervals in both types present valuable opportunities for exploration and development.These data may support future model validations and enhance confidence in exploring and developing marine-continental transitional shale gas.展开更多
The continuous and rapid increase of chemical pollution in surface waters has become a pressing and widely recognized global concern.As emerging contaminants(ECs)in surface waters,pharmaceutical and personal care prod...The continuous and rapid increase of chemical pollution in surface waters has become a pressing and widely recognized global concern.As emerging contaminants(ECs)in surface waters,pharmaceutical and personal care products(PPCPs),and endocrine-disrupting compounds(EDCs)have attracted considerable attention due to their wide occurrence and potential threat to human health.Therefore,a comprehensive understanding of the occurrence and risks of ECs in Chinese surface waters is urgently required.This study summarizes and assesses the environmental occurrence concentrations and ecological risks of 42 pharmaceuticals,15 personal care products(PCPs),and 20 EDCs frequently detected in Chinese surface waters.The ECs were primarily detected in China’s densely populated and highly industrialized regions.Most detected PPCPs and EDCs had concentrations between ng/L toμg/L,whereas norfloxacin,caffeine,and erythromycin had relatively high contamination levels,even exceeding 2000 ng/L.Risk evaluation based on the risk quotient method revealed that 34 PPCPs and EDCs in Chinese surface waters did not pose a significant risk,whereas 4-nonylphenol,4-tert-octylphenol,17α-ethinyl estradiol,17β-estradiol,and triclocarban did.This review provides a comprehensive summary of the occurrence and associated hazards of typical PPCPs and EDCs in Chinese surface waters over the past decade,and will aid in the regulation and control of these ECs in Chinese surface waters。展开更多
Forest fires are natural disasters that can occur suddenly and can be very damaging,burning thousands of square kilometers.Prevention is better than suppression and prediction models of forest fire occurrence have dev...Forest fires are natural disasters that can occur suddenly and can be very damaging,burning thousands of square kilometers.Prevention is better than suppression and prediction models of forest fire occurrence have developed from the logistic regression model,the geographical weighted logistic regression model,the Lasso regression model,the random forest model,and the support vector machine model based on historical forest fire data from 2000 to 2019 in Jilin Province.The models,along with a distribution map are presented in this paper to provide a theoretical basis for forest fire management in this area.Existing studies show that the prediction accuracies of the two machine learning models are higher than those of the three generalized linear regression models.The accuracies of the random forest model,the support vector machine model,geographical weighted logistic regression model,the Lasso regression model,and logistic model were 88.7%,87.7%,86.0%,85.0%and 84.6%,respectively.Weather is the main factor affecting forest fires,while the impacts of topography factors,human and social-economic factors on fire occurrence were similar.展开更多
The occurrence characteristics of shale oil are of great significance to the movability of shale oil.In this study,the occurrence characteristics of oil in the shale matrix at Funing Formation shale in Subei Basin wer...The occurrence characteristics of shale oil are of great significance to the movability of shale oil.In this study,the occurrence characteristics of oil in the shale matrix at Funing Formation shale in Subei Basin were quantitatively evaluated by organic geochemistry and microscopic pore structure characterization experiments.The Multiple Isothermal Stages Pyrolysis(MIS)experiment results show that the content of total oil,adsorbed oil,and free oil in the shales are 3.15-11.25 mg/g,1.41-4.95 mg/g,and 1.74-6.51 mg/g,respectively.among which the silicon-rich shale has the best oil-bearing.The relative content of free oil shows an increasing trend in pores with pore diameters greater than 3 nm.When the relative content of free oil reaches 100%,the pore size of silicon-rich shale is about 200 nm,while that of calcium-rich shale,clay-rich shale,and siliceous mixed shale is about 10 nm.The occurrence law of adsorbed oil is opposite to that of free oil,which indicates that shale oil will occur in the pores and fractures in a free state in a more extensive pore size range(>200 nm).This study also enables us to further understand the occurrence characteristics of shale oil under the interaction of occurrence state and occurrence space.展开更多
The effect of alumina occurrence form on the metallurgical properties of both hematite and magnetite pellets was investigated at the same Al_(2)O level of 2 wt.%,including reduction index(RI),low-temperature reduction...The effect of alumina occurrence form on the metallurgical properties of both hematite and magnetite pellets was investigated at the same Al_(2)O level of 2 wt.%,including reduction index(RI),low-temperature reduction disintegration index(RDI),reduction swelling index(RSI),and high-temperature softening-dripping performance.The mineralogy of fired pellets was also studied to reveal the influence of alumina occurrence form on the phase composition and microstructure.From the results,the alumina occurrence form presents tremendous impacts on the metallurgical perfor-mance of both magnetite and hematite pellets.Addition of all alumina occurrence forms contributes to inferior reducibility of pellets,especially in the case of gibbsite for magnetite pellets with a RI of 58.4%and kaolinite for hematite pellets with a RI of 56.8%.However,addition of all alumina occurrence forms improves the RDI of magnetite pellets,while there is no significant difference among various alumina occurrence forms.In contrast,alumina occurrence forms have little influence on the RDI of hematite pellets.The presence of free alumina,gibbsite,and kaolinite tends to improve the RSI of hematite and magnetite pellets,whereas hercynite gives the opposite trend with a RSI of 25.6%.For softening-dripping performance of magnetite pellets,all alumina occurrence forms contribute to narrower softening-melting interval.Meanwhile,alumina,gibbsite,and kaolinite give narrower softening-dripping interval,at 229,217,and 88℃,respectively,whereas addition of hercynite results in the largest melting range at 276℃ due to its high melting point.Regarding hematite pellets,free alumina,gibbsite,and hercynite tend to enlarge melting range,whereas kaolinite contributes to lower dripping temperature of 1148℃ and narrow softening-dripping interval of 88℃ due to the formation of a greater amount of slag phase at high temperatures.展开更多
Weathered crust elution-deposited rare earth ore is crucial source of medium and heavy rare earths,with in-situ leaching being the most common mining method.The high contents of impurity of aluminum in the leach solut...Weathered crust elution-deposited rare earth ore is crucial source of medium and heavy rare earths,with in-situ leaching being the most common mining method.The high contents of impurity of aluminum in the leach solution are a significant challenge for the subsequent enrichment process of rare earths.A comprehensive understanding of the occurrences and vertical distribution of aluminum and rare earths within typical vertical profiles can provide valuable insights into entire design of the in-situ leaching.This paper improves a five-step sequential extraction method to analyze the occurrence and vertical distribution of rare earths and aluminum in vertical profiles from Chongzuo and Longyan.Experimental results demonstrate that soil solution pH is the main factor affecting the vertical distribution of ionexchangeable rare earths.Both samples have distinct areas of enrichment for ion-exchangeable rare earths or aluminum.Ion-exchangeable rare earths are primary concentrated in the middle and lower parts of the ore layer(4-13 m in Chongzuo,14-22 m in Longyan),while the ion-exchangeable aluminum is mainly enriched in the upper part of the ore layer(1-5 m in Chongzuo,and 2-14 m in Longyan).The vertical distribution of inorganic hydroxy aluminum is likely influenced by the micromorphology and particle size of the clay minerals.The inorganic hydroxy aluminum concentration in Chongzuo samples decreases continuously from 415.65 to 120.95 mg/kg with increasing sampling depth,whereas the concentration in Longyan samples(110.55-171.27 mg/kg)is almost independence with sampling depth.These results provide direct guidance for the entire design of the injection well depth and the leaching parameters,thereby inhibiting the leaching of impurity of aluminum and lower the consumption of leaching agent.展开更多
Characterizing the microscopic occurrence and distribution of in-situ pore water and oil is crucial for resource estimation and development method selection of shale oil.In this paper,a series of nuclear magnetic reso...Characterizing the microscopic occurrence and distribution of in-situ pore water and oil is crucial for resource estimation and development method selection of shale oil.In this paper,a series of nuclear magnetic resonance(NMR)experiments were conducted on shales from the Gulong Sag,Songliao Basin,China,at AR,WR-AR,WOR-AR,Dry,SO,and WR states.In-situ pore water and oil were reconstructed after WOR-AR.An improved T1-T2pattern for shale oil reservoirs comprising water and oil was proposed to classify and quantitatively detect pore fluids at different occurrence states.The total and free oil contents derived from NMR T1-T2spectra at AR states were found to correlate well with those from multistage Rock-Eval.Moreover,the NMR-calculated total and free oil are generally larger than those measured from multistage Rock-Eval,whereas adsorbed oil is the opposite,which implies that adsorbed,bound,and movable oils in shale pores can be accurately and quantitatively detected via NMR,without absorbed hydrocarbons in kerogen.As per the NMR T2and T1-T2spectra at WOR-AR state,the micro-distributions of in-situ pore water and oil were clearly demonstrated.Adsorbed,bound,and movable oils primarily occur in the micropores(<100 nm),mesopores(100-1000 nm),and macropores(>1000 nm),respectively,whereas capillary-bound water is primarily correlated with micropores.Thus,the microscopic occurrence and distribution of adsorbed oil are remarkably affected by pore water,followed by bound oil,and movable oil is hardly affected.This study would be helpful in further understanding the microscopic occurrence characteristics of pore fluids in-situ shale oil reservoirs.展开更多
The objective of this article was to carry out a statistical study of the occurrences of CMEs from solar cycles 23 and 24 and to deduce interpretations as a contribution to a greater understanding of heliosphere dynam...The objective of this article was to carry out a statistical study of the occurrences of CMEs from solar cycles 23 and 24 and to deduce interpretations as a contribution to a greater understanding of heliosphere dynamics. Thus, from the statistical examination of the occurrences according to the phases it appeared that solar cycle 23 (SC23) counted 13207 occurrences of CMEs while 16510 were counted for solar cycle 24 (SC24). These occurrences of CMEs are correlated to the sunspot cycle because in each of these cycles we would note the predominance of the phase maximum (1478 for SC23 and 2338 for SC24) over the ascending phases (550 for SC23 and 1559 for the SC24) and descending (1197 for the SC23 and 1178 for the SC24) and these predominate on the minimum phase (206 for the SC23 and 834 for the SC24). However, the percentages per phase in each cycle show that SC23 was only predominant over SC24 at the maximum phase (43.08% for SC23 and 39.57% for SC24). From this correlation, some authors therefore suggest that the toroidal magnetic field would be the cause of the ejections of these CMEs. The annual statistical examination confirms the correlation with the sunspot cycle but nevertheless reveals in the descending phase of SC23 two unusual peaks in 2005 and 2007 and a drop-in sunspot activity of 42% from SC23 to SC24 while that we would note an increase in the activity of CME occurrences of 36% at SC24, thus suggesting that CMEs can occur without the toroidal magnetic field being the cause, particularly from the coronal holes. The seasonal statistical examination shows for its part that out of the total of 29717 occurrences of CMEs of the two cycles that spring (28%) was the most active than summer (25%) and summer over autumn (24%) and finally autumn over winter (23%) thus revealing that: The ascending phase of the cycle was only the most active during the winter seasons in spring and the descending phase only during the rest of the seasons. Finally, the monthly statistical examination of the occurrences of CMEs corroborates the seasonal statistical examination by the presence of two maximum peaks (May and October) and two minimum peaks (February and August).展开更多
To explore the occurrence phases and enrichment mechanism of rare earth elements(REEs)in cobalt-rich crusts,this study analyzes the mineral composition and REE contents of the samples from Marcus-Wake Seamounts by XRD...To explore the occurrence phases and enrichment mechanism of rare earth elements(REEs)in cobalt-rich crusts,this study analyzes the mineral composition and REE contents of the samples from Marcus-Wake Seamounts by XRD,ICP-OES and ICP-MS.The results show that,(1)the cobalt-rich crusts contain the major crystalline mineral(vernadite),the secondary minerals(quartz,plagioclase and carbonate fluorapatite),and a large amount of amorphous ferric oxyhydroxides(FeOOH).(2)The cobalt-rich crusts contains higher Mn(10.83%to 28.76%)and Fe(6.14%to 18.86%)relative to other elements,and are enriched in REEs,with total REE contents of 1563−3238μg/g and Ce contents of 790−1722μg/g.Rare earth element contents of the old crusts are higher than those of the new crusts.Moreover,the non-phosphatized crusts have positive Ce and negative Y anomalies,and yet the phosphatized crusts have positive Ce and positive Y anomalies,indicating that cobalt-rich crusts is hydrogenetic and REEs mainly come from seawater.(3)Analytical data also show that the occurrence phases of elements in cobalt-rich crusts are closely related to their mineral phases.In the non-phosphatized crusts,REEs are adsorbed by colloidal particles into the crusts(about 67%of REEs in the Fe oxide phase,and about 17%of REEs in the Mn oxide phase).In contrast,in the phosphatized crusts(affected by the phosphatization),REEs may combine with phosphate to form rare earth phosphate minerals,and about 64%of REEs are enriched in the residual phase containing carbonate fluorapatite,but correspondingly the influence of Fe and Mn oxide phases on REEs enrichment is greatly reduced.In addition,the oxidizing environment of seawater,high marine productivity,phosphatization,and slow growth rate can promote the REE enrichment.This study provides a reference for the metallogenesis of cobalt-rich crusts in the Pacific.展开更多
[Objectives]This study was conducted to investigate the species and occurrence patterns of main pests in the Chinese chive(Allium tuberosum)fields in Shijiazhuang.[Methods]Our research group conducted a systematic inv...[Objectives]This study was conducted to investigate the species and occurrence patterns of main pests in the Chinese chive(Allium tuberosum)fields in Shijiazhuang.[Methods]Our research group conducted a systematic investigation on the types and occurrence of major pests in Chinese chive fields in Shijiazhuang from April 2019 to November 2020 using the Malaise net method.[Results]The main pests harming Chinese chives in the region included Thrips tabaci,Bradysia odoriphaga,Luperomorpha suturalis,Acrolepla alliella,Liriomyza chinensis,and Neotoxoptera formosana.The pest populations in the region mainly experienced two peak periods,from mid June to mid July and from late August to late September.Meanwhile,corresponding green prevention and control measures were proposed based on the occurrence characteristics and biological characteristics of different pests in local chive fields.[Conclusions]Predicting the occurrence of pests in Chinese chive fields can provide basis for farmers to take timely prevention and control measures,reduce the damage of pests in the field to Chinese chives and realize high-quality production of Chinese chive.展开更多
This paper examines the occurrence regularity and comprehensive prevention and control techniques for sunflower downy mildew.It provides a detailed discussion of the pathogens,symptoms,and associated risks,as well as ...This paper examines the occurrence regularity and comprehensive prevention and control techniques for sunflower downy mildew.It provides a detailed discussion of the pathogens,symptoms,and associated risks,as well as the transmission pathways,underlying causes,and prevention and control techniques related to sunflower downy mildew.The aim is to offer valuable references and technical guidance for the effective management of this disease.展开更多
This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) a...This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) and have not (0) occurred in harvested cutblocks. This marking revealed 1) where off-road operations were likely done on moist to wet and unfrozen soils;and 2) whether the ruts so incurred were water-logged at the time of imaging. Through geospatial processing of the NB-wide digital elevation model (DEM, available at 1 m resolution), the following attributes were added to each of the marked rut and no-rut locations: 1) the cartographic depth-to-water (DTW) as referenced to the nearest flow channels with >1 and >4 ha upslope flow accumulation areas (FA);2) the topographic position index (TPI) in reference to the mean annulus elevation 50 m away from each DEM cell;3) mean slope and curvatures within each cell-surrounding 10-m circle;4) the terrain wetness index (TWI);5) soil association type according to the NB forest soil map, adjusted for NB’s most recent hydrographic network delineations for waterbodies and wetlands. Subjecting these data to logistic regression analysis revealed that image-located off-road rutting occurred at about 90% probability in water-accumulating zones where TPI is <0 m and DTW is <1 m. Using slope, curvature, TWI, and soil type as additional rut occurrence predictors did not affect this zonation significantly.展开更多
基金Funding support for the Crop Pest Surveillance and Advisory Project(CROPSAP)。
文摘Background Cotton crop is infested by numerous arthropod pests from sowing to harvesting,causing substantial direct and indirect yield losses.Knowledge of seasonal population trends and the relative occurrence of pests and their natural enemies is required to minimize the pest population and yield losses.In the current study,analysis of the seasonal population trend of pests and natural enemies and their relative occurrence on cultivars of three cotton species in Central India has been carried out.Results A higher number and diversity of sucking pests were observed during the vegetative cotton growth stage(60 days after sowing),declining as the crop matured.With the exception of cotton jassid(Amrasca biguttula biguttula Ishida),which caused significant crop damage mainly from August to September;populations of other sucking insects seldom reached economic threshold levels(ETL)throughout the studied period.The bollworm complex populations were minimal,except for the pink bollworm(Pectinophora gossypiella Saunders),which re-emerged as a menace to cotton crops during the cotton cropping season 2017–2018 due to resistance development against Bt-cotton.A reasonably good number of predatory arthropods,including coccinellids,lacewings,and spiders,were found actively preying on the arthropod pest complex of the cotton crop during the early vegetative growth stage.Linear regression indicates a significant relationship between green boll infestations and pink bollworm moths in pheromone traps.Multiple linear regression analyse showed mean weekly weather at one-or two-week lag periods had a significant impact on sucking pest population(cotton aphid,cotton jassid,cotton whitefly,and onion thrips)fluctuation.Gossypium hirsutum cultivars RCH 2 and DCH 32,and G.barbadense cultivar Suvin were found susceptible to cotton jassid and onion thrips.Phule Dhanvantary,an G.arboreum cotton cultivar,demonstrated the highest tolerance among all evaluated cultivars against all sucking pests.Conclusion These findings have important implications for pest management in cotton crops.Susceptible cultivars warrant more attention for plant protection measures,making them more input-intensive.The choice of appropriate cultivars can help minimize input costs,thereby increasing net returns for cotton farmers.
基金financially supported by the State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development(33550000-22-ZC0613-0006)National Natural Science Foundation of China(42202133)+2 种基金CNPC Innovation Fund(2022DQ02-0106)Strategic Cooperation Technology Projects of the CNPC and CUPB(ZLZX2020-01-05)Key Laboratory of Tectonics and Petroleum Resources(China University of Geosciences),Ministry of Education,China(TPR-2023-05)。
文摘Alkaline lacustrine shale is highly heterogeneous,and the complex relationship between the organicinorganic porosity network and hydrocarbon occurrence restricts the effectiveness of shale oil exploration and development.Herein,we investigated the Fengcheng Formation(P_(1)f)in Mahu Sag.This study integrated geochemistry,Soxhlet extraction,scanning electron microscopy,gas adsorption,and nuclear magnetic resonance T_(1)-T_(2)spectroscopy to elucidate the microscopic oil occurrence mechanisms in shales.Results indicate the presence of felsic shale,dolomitic shale,lime shale,and mixed shale within the P_(1)f.Matrix pores and microfractures associated with inorganic minerals are the predominant pore types in P_(1)f.Adsorbed oil primarily resides on the surfaces of organic matter and clay minerals,while free oil predominantly occupies inorganic pores and microfractures with larger pore sizes.Variations exist in the quantity and distribution of shale oil accumulation across different scales,where free oil and adsorbed oil are governed by dominant pores with diameters exceeding 10 nm and ineffective pores with diameters below 10 nm,respectively.Shale oil occurrence characteristics are influenced by organic matter,pore structure,and mineral composition.Felsic shale exhibits a high abundance of dominant pores,possesses the highest oil content,predominantly harbors free oil within these dominant pores,and demonstrates good mobility.Fluid occurrence in dolomitic shale and lime shale is intricate,with low oil content and a free oil to adsorbed oil ratio of 1:1.Mixed shale exhibits elevated clay mineral content and a scarcity of dominant pores.Moreover,ineffective pores contain increased bound water,resulting in medium oil content and limited mobility predominantly due to adsorption.Presently,shale oil mainly occurs in the dominant pores with a diameter larger than 10 nm in a free state.During the exploration and development of alkaline lacustrine shale oil resources,emphasis should be placed on identifying sweet spots within the felsic shale characterized by dominant pores.
文摘In this study we review the occurrence of different types (A, B, C, M, and X classes) of solar flares during different solar cycle phases from 1996 to 2019 covering the solar cycles 23 and 24. During this period, a total of 19,126 solar flares were observed regardless the class: 3548 flares in solar cycle 23 (SC23) and 15,668 flares in solar cycle 24 (SC24). Our findings show that the cycle 23 has observed the highest occurrences of M-class and X-class flares, whereas cycle 24 has pointed out a predominance of B-class and C-class flares throughout its different phases. The results indicate that the cycle 23 was magnetically more intense than cycle 24, leading to more powerful solar flares and more frequent geomagnetic storms, capable of generating significant electromagnetic emissions that can affect satellites and GPS signals. The decrease in intense solar flares during cycle 24 compared to cycle 23 reflects an evolution in solar activity patterns over time.
基金financially supported by the Natural Science Foundation of Hunan Province,China(No.2024JJ2074)the National Natural Science Foundation of China(No.22376221)the Young Elite Scientists Sponsorship Program by CAST,China(No.2023QNRC001).
文摘Tailings produced by mining and ore smelting are a major source of soil pollution.Understanding the speciation of heavy metals(HMs)in tailings is essential for soil remediation and sustainable development.Given the complex and time-consuming nature of traditional sequential laboratory extraction methods for determining the forms of HMs in tailings,a rapid and precise identification approach is urgently required.To address this issue,a general empirical prediction method for HM occurrence was developed using machine learning(ML).The compositional information of the tailings,properties of the HMs,and sequential extraction steps were used as inputs to calculate the percentages of the seven forms of HMs.After the models were tuned and compared,extreme gradient boosting,gradient boosting decision tree,and categorical boosting methods were found to be the top three performing ML models,with the coefficient of determination(R^(2))values on the testing set exceeding 0.859.Feature importance analysis for these three optimal models indicated that electronegativity was the most important factor affecting the occurrence of HMs,with an average feature importance of 0.4522.The subsequent use of stacking as a model integration method enabled the ability of the ML models to predict HM occurrence forms to be further improved,and resulting in an increase of R^(2) to 0.879.Overall,this study developed a robust technique for predicting the occurrence forms in tailings and provides an important reference for the environmental assessment and recycling of tailings.
基金Project supported by Guizhou Provincial Basic Research Program (Natural Science)(Qian Ke He Basic-ZK 2024 General 626)National Natural Science Foundation of China (52164018)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology (13210025)。
文摘Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.
基金supported by the National Natural Science Foundation of China(42302160)the Sanya City Science and Technology Innovation Project(2022KJCX51)the Support Plan for Outstanding Youth Innovation Team in Shandong Higher Education Institutions(2022KJ060).
文摘The microscopic occurrence characteristics primarily constrain the enrichment and mobility of shale oil.This study collected the lacustrine shales from the Palaeogene Funing Formation in the Gaoyou Sag, Subei Basin. Conventional and multistage Rock-Eval, scanning electron microscopy, and nuclear magnetic resonance(NMR) T1-T2were performed to analyze the contents and occurrence characteristics of shale oil. Low-temperature nitrogen adsorption-desorption(LTNA/D) experiments were conducted on the shales before and after extraction. The relationships between shale oil occurrence with organic matter and pore structures were then discussed. Predominantly, the shale oil in the Funing Formation is found within fractures, with secondary occurrences in interparticle pores linked to brittle minerals and sizeable intraparticle pores associated with clay minerals. The selected shales can be categorized into two types based on the nitrogen isotherms. Type A shales are characterized by high contents of felsic and calcareous minerals but low clay minerals, with larger TOC and shale oil values. Conversely, Type B shales are marked by abundant clay minerals but diminished TOC and shale oil contents. The lower BET specific surface area(SSA), larger average pore diameter, and simpler pore surfaces and pore structures lead to the Type A shales being more conducive to shale oil enrichment and mobility. Shale oil content is predominantly governed by the abundance of organic matter, while an overabundance of organic matter typically equates to a reduced ratio of free oil and diminished fluidity. The BET SSA, volumes of pores less than 25 and 100 nm at extracted state all correlate negatively with total and adsorbed oil contents but display no correlation with free oil, while they have positive relationships with capillary-bound water.Consequently, pore water is mainly saturated in micropores(<25 nm) and minipores(25-100 nm), as well as adsorbed oil, while free oil, i.e., bound and movable oil, primarily exists in mesopores(100-1000 nm) and macropores(>1000 nm). These findings may enhance the understanding of the microscopic occurrence characteristics of shale oil and will contribute to guide resource estimation and shale oil sweet spot exploitation in the Gaoyou Sag, Subei Basin.
基金jointly supported by project of the China Geological Survey(DD20243375,DD20230478)the Key Research and Development Program of Hunan Province(2023SK2066)the Natural Science Foundation of Hunan Province(2024JJ7620).
文摘Neonicotinoid insecticides(NEOs)have become an integral part of the global insecticide market due to their high efficiency and low toxicity.However,their environmental persistence has raised significant ecological concerns.Dongting Lake represents a vital freshwater lake in China,and its ecosystem health directly affects regional ecological balance and people’s livelihoods.This study systematically investigated the occurrence characteristics and ecological risks of NEOs in water bodies and sediments across the Dongting Lake basin.Based on surface water and sediment samples collected from 26 representative sampling sites,this study quantified nine NEOs using liquid chromatography triple quadrupole mass spectrometry.Furthermore,it assessed ecological risks posed by the NEOs using the risk quotient(RQ)method and fugacity modeling.The results revealed the presence of six NEOs in the water bodies:imidacloprid(IMI),acetamiprid(ACE),clothianidin(CLO),thiamethoxam(THIA),flonicamid(FLO),and dinotefuran(DIN).The total concentrations of these six NEOs averaged 275.11 ng/L.Five predominant NEOs(i.e.,IMI,THIA,ACE,CLO,and DIN)were identified in the sediments,with a mean concentration of 0.31 ng/g.The NEO concentrations in the water bodies across the Dongting Lake basin increased in the order of the Xiangjiang,Zishui,Yuanjiang,and Lishui rivers(collectively referred to as the Four Rivers),the mainstream of Dongting Lake,the Xinqiang River,the Miluo River,and the Hudu,Ouchi,and Songzi rivers(collectively referred to as the Three Outlets).Sediments from tributaries progressively accumulate in the lake.The ecological risk assessment identified IMI and DIN as the highest-risk compounds(RQ>1),with high-risk areas concentrated in the mainstream of Dongting Lake and the Ouchi,Miluo,and Hudu rivers.The fugacity model showed that IMI,ACE,and THIA are prone to diffuse from sediments to water bodies in most areas,with fugacity fractions(ff)values of greater than 0.5.In contrast,the mainstream of Dongting Lake acts as a sink of CLO and DIN(ff values:<0.5).Sediments at the lake’s outlet emerge as an important sink of NEOs.Based on the results of this study,it is advisable to strengthen the supervision of NEO applications in agricultural areas and to implement zonal control strategies.These measures will help reduce ecological risks and protect the safety of water ecosystems in the Dongting Lake region.
基金supported by the National Natural Science Foundation of China(No.41830431)the Shandong Provincial Key Research and Development Program(No.2020ZLYS08).
文摘Understanding the occurrence state of shale oil is crucial for the effective development of shale oil resources.Although the second member of the Kongdian Formation(Ek2)is a key interval for lacustrine shale oil production in the Cangdong Sag,Bohai Bay Basin,the occurrence state and controlling factors of shale oil in this formation remain poorly understood.This study established a multi-step programmed pyrolysis,combined with a light hydrocarbon recovery scheme,to quantitatively characterize the shale oil in different occurrence states.An integrated approach utilizing Rock-Eval pyrolysis,pyrolysis-gas chromatography,and crude oil gas chromatography was employed.Factors influencing the shale oil occurrence state were analyzed from petrology and organic geochemistry perspectives.The study revealed significant variations of shale oil occurrence states within the Ek2,attributed to differences in sedimentary organic matter,mineral compositions,sedimentary structures,and thermal maturity.Felsic laminae are the primary reservoir space for oil in laminated shales,and the frequent interbedding of felsic and organic-rich laminae facilitates the retention of free oil.The contents of free and adsorbed oil are primarily influenced by organic matter content and shale storage capacity,both of which exhibit distinct occurrence patterns.Based on the shale reservoir quality classification using the pyrolysis values of S1-1+S1-2 and(S1-1+S1-2)×100/TOC,the Ek2 shale demonstrates significant exploitation potential,with the first-level reservoirs comprising 66%,second-level reservoirs 11%,and third-level reservoirs 23%.These findings provide new insights into the geological accumulation and production of shale oil.
基金the Science and Technology Cooperation Project of the CNPC-SWPU Innovation Alliance,China(No.2020CX030101)the National Natural Science Foundation of China(No.42222209)the Scientific Research and Technological Development Program of CNPC,China(No.2023ZZ0801).
文摘Pore structure characteristics,gas content,and micro-scale gas occurrence mechanisms were investigated in the Shan_(2)^(3)sub-member marine-continental transitional shale of the southeastern margin of the Ordos Basin using scanning electron microscope images,lowtemperature N_(2)/CO_(2)adsorption and high-pressure mercury intrusion,methane isothermal adsorption experiments,and CH4-saturated nuclear magnetic resonance(NMR).Two distinct shale types were identified:organic pore-rich shale(Type OP)and microfracture-rich shale(Type M).The Type OP shale exhibited relatively well-developed organic matter pores,while the Type M shale was primarily characterized by a high degree of microfracture development.An experimental method combining methane isothermal adsorption on crushed samples and CH4-saturated NMR of plug samples was proposed to determine the adsorbed gas,free gas,and total gas content under high temperature and pressure conditions.There were four main research findings.(1)Marine-continental transitional shale exhibited substantial total gas content in situ,ranging from 2.58 to 5.73 cm^(3)/g,with an average of 4.35 cm^(3)/g.The adsorbed gas primarily resided in organic matter pores through micropore filling and multilayer adsorption,followed by multilayer adsorption in clay pores.(2)The changes in adsorbed and free pore volumes can be divided into four stages.Pores of<5 nm exclusively contain adsorbed gas,while those of 5-20 nm have a high proportion of adsorbed gas alongside free gas.Pores ranging from 20 to 100 nm have a high proportion of free gas and few adsorbed gas,while pores of>100 nm and microfractures are almost predominantly free gas.(3)The proportion of adsorbed gas in Type OP shale exceeds that in Type M,reaching 66%.(4)Methane adsorbed in Type OP shale demonstrates greater desorption capability,suggesting a potential for enhanced stable production,which finds support in existing production well data.However,it must be emphasized that high-gas-bearing intervals in both types present valuable opportunities for exploration and development.These data may support future model validations and enhance confidence in exploring and developing marine-continental transitional shale gas.
基金supported by the National Natural Science Foundation of China(No.22176199)the Key R&D Program of Shandong Province(No.2020CXGC011202)+1 种基金the Jinan University and Institute Innovation Team Project(No.2021GXRC061)the Research Center for Eco-Environmental Science(No.RCEES-TDZ-2021-14).
文摘The continuous and rapid increase of chemical pollution in surface waters has become a pressing and widely recognized global concern.As emerging contaminants(ECs)in surface waters,pharmaceutical and personal care products(PPCPs),and endocrine-disrupting compounds(EDCs)have attracted considerable attention due to their wide occurrence and potential threat to human health.Therefore,a comprehensive understanding of the occurrence and risks of ECs in Chinese surface waters is urgently required.This study summarizes and assesses the environmental occurrence concentrations and ecological risks of 42 pharmaceuticals,15 personal care products(PCPs),and 20 EDCs frequently detected in Chinese surface waters.The ECs were primarily detected in China’s densely populated and highly industrialized regions.Most detected PPCPs and EDCs had concentrations between ng/L toμg/L,whereas norfloxacin,caffeine,and erythromycin had relatively high contamination levels,even exceeding 2000 ng/L.Risk evaluation based on the risk quotient method revealed that 34 PPCPs and EDCs in Chinese surface waters did not pose a significant risk,whereas 4-nonylphenol,4-tert-octylphenol,17α-ethinyl estradiol,17β-estradiol,and triclocarban did.This review provides a comprehensive summary of the occurrence and associated hazards of typical PPCPs and EDCs in Chinese surface waters over the past decade,and will aid in the regulation and control of these ECs in Chinese surface waters。
基金This research was funded by the National Natural Science Foundation of China(grant no.32271881).
文摘Forest fires are natural disasters that can occur suddenly and can be very damaging,burning thousands of square kilometers.Prevention is better than suppression and prediction models of forest fire occurrence have developed from the logistic regression model,the geographical weighted logistic regression model,the Lasso regression model,the random forest model,and the support vector machine model based on historical forest fire data from 2000 to 2019 in Jilin Province.The models,along with a distribution map are presented in this paper to provide a theoretical basis for forest fire management in this area.Existing studies show that the prediction accuracies of the two machine learning models are higher than those of the three generalized linear regression models.The accuracies of the random forest model,the support vector machine model,geographical weighted logistic regression model,the Lasso regression model,and logistic model were 88.7%,87.7%,86.0%,85.0%and 84.6%,respectively.Weather is the main factor affecting forest fires,while the impacts of topography factors,human and social-economic factors on fire occurrence were similar.
基金This work was financially supported by the National Natural Science Foundation of China(41972123,41922015)the Natural Science Foundation of Shandong Province(ZR2020QD036).
文摘The occurrence characteristics of shale oil are of great significance to the movability of shale oil.In this study,the occurrence characteristics of oil in the shale matrix at Funing Formation shale in Subei Basin were quantitatively evaluated by organic geochemistry and microscopic pore structure characterization experiments.The Multiple Isothermal Stages Pyrolysis(MIS)experiment results show that the content of total oil,adsorbed oil,and free oil in the shales are 3.15-11.25 mg/g,1.41-4.95 mg/g,and 1.74-6.51 mg/g,respectively.among which the silicon-rich shale has the best oil-bearing.The relative content of free oil shows an increasing trend in pores with pore diameters greater than 3 nm.When the relative content of free oil reaches 100%,the pore size of silicon-rich shale is about 200 nm,while that of calcium-rich shale,clay-rich shale,and siliceous mixed shale is about 10 nm.The occurrence law of adsorbed oil is opposite to that of free oil,which indicates that shale oil will occur in the pores and fractures in a free state in a more extensive pore size range(>200 nm).This study also enables us to further understand the occurrence characteristics of shale oil under the interaction of occurrence state and occurrence space.
基金supported by the National Natural Science Foundation of China(No.52004339)the Key Research and Development Project of Hunan Province,China(No.2022SK2075)+1 种基金China Baowu Low Carbon Metallurgy Innovation Foudation(BWLCF_(2)02216)the Open Sharing Fund for the Large-Scale Instruments and Equipment of Central South University(CSUZC202207).
文摘The effect of alumina occurrence form on the metallurgical properties of both hematite and magnetite pellets was investigated at the same Al_(2)O level of 2 wt.%,including reduction index(RI),low-temperature reduction disintegration index(RDI),reduction swelling index(RSI),and high-temperature softening-dripping performance.The mineralogy of fired pellets was also studied to reveal the influence of alumina occurrence form on the phase composition and microstructure.From the results,the alumina occurrence form presents tremendous impacts on the metallurgical perfor-mance of both magnetite and hematite pellets.Addition of all alumina occurrence forms contributes to inferior reducibility of pellets,especially in the case of gibbsite for magnetite pellets with a RI of 58.4%and kaolinite for hematite pellets with a RI of 56.8%.However,addition of all alumina occurrence forms improves the RDI of magnetite pellets,while there is no significant difference among various alumina occurrence forms.In contrast,alumina occurrence forms have little influence on the RDI of hematite pellets.The presence of free alumina,gibbsite,and kaolinite tends to improve the RSI of hematite and magnetite pellets,whereas hercynite gives the opposite trend with a RSI of 25.6%.For softening-dripping performance of magnetite pellets,all alumina occurrence forms contribute to narrower softening-melting interval.Meanwhile,alumina,gibbsite,and kaolinite give narrower softening-dripping interval,at 229,217,and 88℃,respectively,whereas addition of hercynite results in the largest melting range at 276℃ due to its high melting point.Regarding hematite pellets,free alumina,gibbsite,and hercynite tend to enlarge melting range,whereas kaolinite contributes to lower dripping temperature of 1148℃ and narrow softening-dripping interval of 88℃ due to the formation of a greater amount of slag phase at high temperatures.
基金Project supported by the National Key Research and Development Program of China(2020YFC1909002)the Major Research Plan of the National Natural Science Foundation of China(91962211)the Science and Technology Innovation Fund of GRINM(2022PD0102)。
文摘Weathered crust elution-deposited rare earth ore is crucial source of medium and heavy rare earths,with in-situ leaching being the most common mining method.The high contents of impurity of aluminum in the leach solution are a significant challenge for the subsequent enrichment process of rare earths.A comprehensive understanding of the occurrences and vertical distribution of aluminum and rare earths within typical vertical profiles can provide valuable insights into entire design of the in-situ leaching.This paper improves a five-step sequential extraction method to analyze the occurrence and vertical distribution of rare earths and aluminum in vertical profiles from Chongzuo and Longyan.Experimental results demonstrate that soil solution pH is the main factor affecting the vertical distribution of ionexchangeable rare earths.Both samples have distinct areas of enrichment for ion-exchangeable rare earths or aluminum.Ion-exchangeable rare earths are primary concentrated in the middle and lower parts of the ore layer(4-13 m in Chongzuo,14-22 m in Longyan),while the ion-exchangeable aluminum is mainly enriched in the upper part of the ore layer(1-5 m in Chongzuo,and 2-14 m in Longyan).The vertical distribution of inorganic hydroxy aluminum is likely influenced by the micromorphology and particle size of the clay minerals.The inorganic hydroxy aluminum concentration in Chongzuo samples decreases continuously from 415.65 to 120.95 mg/kg with increasing sampling depth,whereas the concentration in Longyan samples(110.55-171.27 mg/kg)is almost independence with sampling depth.These results provide direct guidance for the entire design of the injection well depth and the leaching parameters,thereby inhibiting the leaching of impurity of aluminum and lower the consumption of leaching agent.
基金financially supported by the National Natural Science Foundation of China(42302160,42302170,42302183,and 42072174)the Sanya City Science and Technology Innovation Project(2022KJCX51)the Support Plan for Outstanding Youth Innovation Team in Shandong Higher Education Institutions(2022KJ060)。
文摘Characterizing the microscopic occurrence and distribution of in-situ pore water and oil is crucial for resource estimation and development method selection of shale oil.In this paper,a series of nuclear magnetic resonance(NMR)experiments were conducted on shales from the Gulong Sag,Songliao Basin,China,at AR,WR-AR,WOR-AR,Dry,SO,and WR states.In-situ pore water and oil were reconstructed after WOR-AR.An improved T1-T2pattern for shale oil reservoirs comprising water and oil was proposed to classify and quantitatively detect pore fluids at different occurrence states.The total and free oil contents derived from NMR T1-T2spectra at AR states were found to correlate well with those from multistage Rock-Eval.Moreover,the NMR-calculated total and free oil are generally larger than those measured from multistage Rock-Eval,whereas adsorbed oil is the opposite,which implies that adsorbed,bound,and movable oils in shale pores can be accurately and quantitatively detected via NMR,without absorbed hydrocarbons in kerogen.As per the NMR T2and T1-T2spectra at WOR-AR state,the micro-distributions of in-situ pore water and oil were clearly demonstrated.Adsorbed,bound,and movable oils primarily occur in the micropores(<100 nm),mesopores(100-1000 nm),and macropores(>1000 nm),respectively,whereas capillary-bound water is primarily correlated with micropores.Thus,the microscopic occurrence and distribution of adsorbed oil are remarkably affected by pore water,followed by bound oil,and movable oil is hardly affected.This study would be helpful in further understanding the microscopic occurrence characteristics of pore fluids in-situ shale oil reservoirs.
文摘The objective of this article was to carry out a statistical study of the occurrences of CMEs from solar cycles 23 and 24 and to deduce interpretations as a contribution to a greater understanding of heliosphere dynamics. Thus, from the statistical examination of the occurrences according to the phases it appeared that solar cycle 23 (SC23) counted 13207 occurrences of CMEs while 16510 were counted for solar cycle 24 (SC24). These occurrences of CMEs are correlated to the sunspot cycle because in each of these cycles we would note the predominance of the phase maximum (1478 for SC23 and 2338 for SC24) over the ascending phases (550 for SC23 and 1559 for the SC24) and descending (1197 for the SC23 and 1178 for the SC24) and these predominate on the minimum phase (206 for the SC23 and 834 for the SC24). However, the percentages per phase in each cycle show that SC23 was only predominant over SC24 at the maximum phase (43.08% for SC23 and 39.57% for SC24). From this correlation, some authors therefore suggest that the toroidal magnetic field would be the cause of the ejections of these CMEs. The annual statistical examination confirms the correlation with the sunspot cycle but nevertheless reveals in the descending phase of SC23 two unusual peaks in 2005 and 2007 and a drop-in sunspot activity of 42% from SC23 to SC24 while that we would note an increase in the activity of CME occurrences of 36% at SC24, thus suggesting that CMEs can occur without the toroidal magnetic field being the cause, particularly from the coronal holes. The seasonal statistical examination shows for its part that out of the total of 29717 occurrences of CMEs of the two cycles that spring (28%) was the most active than summer (25%) and summer over autumn (24%) and finally autumn over winter (23%) thus revealing that: The ascending phase of the cycle was only the most active during the winter seasons in spring and the descending phase only during the rest of the seasons. Finally, the monthly statistical examination of the occurrences of CMEs corroborates the seasonal statistical examination by the presence of two maximum peaks (May and October) and two minimum peaks (February and August).
基金The fund of Laoshan Laboratory under contract Nos LSKJ202203602 and LSKJ202204103the China Ocean Mineral Resource Research and Development Association Research Program under contract No.DY135-C1-1-04the Taishan Scholarship from Shandong Province.
文摘To explore the occurrence phases and enrichment mechanism of rare earth elements(REEs)in cobalt-rich crusts,this study analyzes the mineral composition and REE contents of the samples from Marcus-Wake Seamounts by XRD,ICP-OES and ICP-MS.The results show that,(1)the cobalt-rich crusts contain the major crystalline mineral(vernadite),the secondary minerals(quartz,plagioclase and carbonate fluorapatite),and a large amount of amorphous ferric oxyhydroxides(FeOOH).(2)The cobalt-rich crusts contains higher Mn(10.83%to 28.76%)and Fe(6.14%to 18.86%)relative to other elements,and are enriched in REEs,with total REE contents of 1563−3238μg/g and Ce contents of 790−1722μg/g.Rare earth element contents of the old crusts are higher than those of the new crusts.Moreover,the non-phosphatized crusts have positive Ce and negative Y anomalies,and yet the phosphatized crusts have positive Ce and positive Y anomalies,indicating that cobalt-rich crusts is hydrogenetic and REEs mainly come from seawater.(3)Analytical data also show that the occurrence phases of elements in cobalt-rich crusts are closely related to their mineral phases.In the non-phosphatized crusts,REEs are adsorbed by colloidal particles into the crusts(about 67%of REEs in the Fe oxide phase,and about 17%of REEs in the Mn oxide phase).In contrast,in the phosphatized crusts(affected by the phosphatization),REEs may combine with phosphate to form rare earth phosphate minerals,and about 64%of REEs are enriched in the residual phase containing carbonate fluorapatite,but correspondingly the influence of Fe and Mn oxide phases on REEs enrichment is greatly reduced.In addition,the oxidizing environment of seawater,high marine productivity,phosphatization,and slow growth rate can promote the REE enrichment.This study provides a reference for the metallogenesis of cobalt-rich crusts in the Pacific.
基金Supported by Observation and Monitoring Project of National Data Center for Insect Natural Enemies(ZX09S030101)Technology Demonstration and Service Special Project of Hebei Academy of Agriculture and Forestry Sciences(13000024P0012F410114C).
文摘[Objectives]This study was conducted to investigate the species and occurrence patterns of main pests in the Chinese chive(Allium tuberosum)fields in Shijiazhuang.[Methods]Our research group conducted a systematic investigation on the types and occurrence of major pests in Chinese chive fields in Shijiazhuang from April 2019 to November 2020 using the Malaise net method.[Results]The main pests harming Chinese chives in the region included Thrips tabaci,Bradysia odoriphaga,Luperomorpha suturalis,Acrolepla alliella,Liriomyza chinensis,and Neotoxoptera formosana.The pest populations in the region mainly experienced two peak periods,from mid June to mid July and from late August to late September.Meanwhile,corresponding green prevention and control measures were proposed based on the occurrence characteristics and biological characteristics of different pests in local chive fields.[Conclusions]Predicting the occurrence of pests in Chinese chive fields can provide basis for farmers to take timely prevention and control measures,reduce the damage of pests in the field to Chinese chives and realize high-quality production of Chinese chive.
基金Supported by Wujiaqu City Science and Technology Program Project of the Sixth Division(2214)Science and Technology Research Project in Key Areas of the Xinjiang Production and Construction Corps(2024AB014)+4 种基金Financial Program of the Ninth Division(2024JS007)"Strengthening Youth"Science and Technology Innovation Backbone Talent Program of the Xinjiang Production and Construction Corps(2023007-06)Key R&D Program of Xinjiang Autonomous Region(2023B02008-1)Excellence Youth Program of the Xinjiang Production and Construction CorpsEarmarked Fund for China Agriculture Research System(CARS-16).
文摘This paper examines the occurrence regularity and comprehensive prevention and control techniques for sunflower downy mildew.It provides a detailed discussion of the pathogens,symptoms,and associated risks,as well as the transmission pathways,underlying causes,and prevention and control techniques related to sunflower downy mildew.The aim is to offer valuable references and technical guidance for the effective management of this disease.
文摘This article addresses where ruts are likely to occur during in-field forest operations. This was done by inspecting high-resolution surface images across New Brunswick (NB) and elsewhere to mark where ruts have (1) and have not (0) occurred in harvested cutblocks. This marking revealed 1) where off-road operations were likely done on moist to wet and unfrozen soils;and 2) whether the ruts so incurred were water-logged at the time of imaging. Through geospatial processing of the NB-wide digital elevation model (DEM, available at 1 m resolution), the following attributes were added to each of the marked rut and no-rut locations: 1) the cartographic depth-to-water (DTW) as referenced to the nearest flow channels with >1 and >4 ha upslope flow accumulation areas (FA);2) the topographic position index (TPI) in reference to the mean annulus elevation 50 m away from each DEM cell;3) mean slope and curvatures within each cell-surrounding 10-m circle;4) the terrain wetness index (TWI);5) soil association type according to the NB forest soil map, adjusted for NB’s most recent hydrographic network delineations for waterbodies and wetlands. Subjecting these data to logistic regression analysis revealed that image-located off-road rutting occurred at about 90% probability in water-accumulating zones where TPI is <0 m and DTW is <1 m. Using slope, curvature, TWI, and soil type as additional rut occurrence predictors did not affect this zonation significantly.
