In-situ analysis and genetic investigation of Li-bearing minerals in McDermitt clay-type lithium deposit,Nevada,USA

Clay-type Li deposits are poised to play a pivotal role in addressing the surging global demand for Li.The McDermitt clay-type Li deposit,located in Nevada,is the largest Li deposit in the United States,with Li hosted by a clay-rich sequence of smectite-dominated intervals and illite-dominated intervals,respectively.However,the occurrence of Li and the genesis of Li-bearing minerals within smectite-dominated intervals have not been thoroughly investigated in previous research.Here,we studied the mineralogy,the in-situ Li distribution,and the bonding environments of Li within the smectite intervals using a combination of instru-mental techniques including scanning electron microscope,transmission electron microscope,time-of-flight secondary ion mass spectrometry,and nuclear magnetic resonance.Our results indicate that the smectite exhibits low crystallinity characteristics of lacustrine clay authigenesis and is com-monly found tofill the interstices among volcanic minerals or envelop them;Li is mainly hosted by Mg-smectite rather than the volcanic minerals.Within the tuffaceous sediment samples,the volcanic glass has undergone a transformation,resulting in its complete disappearance and alteration into clay minerals.Owing to the octahedral sites of Mg-smectite bounded in Li,it is referred to be hectorite.We interpret that the hectorite’s precipitation occurs in a high saline-alkaline water environment,a result of McDermitt tuffdissolution.This conclusion can be supported by the coexistence of spherulitic calcite and hectorite.Overall,this study confirms hectorite as the main Li-bearing mineral and increases the understanding of the genetic model of hectorite formation in intracontinental caldera basins.

An updated inventory of marine opisthobranch(Mollusca,Gastropoda)from the territorial waters of the Republic of Mauritius

Island ecosystems support diverse aquatic invertebrate communities comprising endemic taxa.Documentation of existing species is important for conservation.In this study,a checklist of marine opisthobranch from the Republic of Mauritius is presented.A combination of benthic surveys(50 m×5 m in triplicates),rover diving techniques and photo documentation were used over two years(2018–2020)within 35 sheltered and unsheltered lagoons.Morphological and molecular analysis were used for identification.Species composition within sheltered and unsheltered areas in Mauritius was estimated using the Bray-Curtis similarity.The checklist featured 117 species belonging to 61 genera and 28families,of which 13 are new records.The findings increased the knowledge of opisthobranch diversity from the Mauritius by 15.4%.Among the listed species,the distribution range of Cyerce nigra,Actinocyclus papillatus,and Phyllidia picta extended from the Western Pacific to the South Western Indian Ocean.Molecular analysis of the undescribed Gymnodoris sp.showed it resembled Gymnodoris sp.from Hawaii and were different by a genetic distance value of 10.6%.The species richness and evenness were higher within the sheltered regions of Mauritius which harboured the food resource of opisthobranch.These areas as compared to unsheltered regions were heavily populated,suggesting the probable influence of wave actions on opisthobranch diversity and abundance.The order Nudibranchia was reported as most speciose,with 86 species.The Sacoglossa and Nudibranchia were observed only on macroalgae and sponges respectively.High abundance was also recorded on shipwrecks which are the most common form of artificial reefs.With the inclusion of observations from previous studies,201species belonging to 94 genera and 36 families are now known from the Mauritius.

Modeling the effect of stand and site characteristics on the probability of mistletoe infestation in Scots pine stands using remote sensing data

Over the past decade,the presence of mistletoe(Viscum album ssp.austriacum)in Scots pine stands has increased in many European countries.Understanding the factors that influence the occurrence of mistletoe in stands is key to making appropriate forest management decisions to limit damage and prevent the spread of mistletoe in the future.Therefore,the main objective of this study was to determine the probability of mistletoe occurrence in Scots pine stands in relation to stand-related endogenous factors such as age,top height,and stand density,as well as topographic and edaphic factors.We used unmanned aerial vehicle(UAV)imagery from 2,247 stands to detect mistletoe in Scots pine stands,while majority stand and site characteristics were calculated from airborne laser scanning(ALS)data.Information on stand age and site type from the State Forest database were also used.We found that mistletoe infestation in Scots pine stands is influenced by stand and site characteristics.We documented that the densest,tallest,and oldest stands were more susceptible to mistletoe infestation.Site type and specific microsite conditions associated with topography were also important factors driving mistletoe occurrence.In addition,climatic water balance was a significant factor in increasing the probability of mistletoe occurrence,which is important in the context of predicted temperature increases associated with climate change.Our results are important for better understanding patterns of mistletoe infestation and ecosystem functioning under climate change.In an era of climate change and technological development,the use of remote sensing methods to determine the risk of mistletoe infestation can be a very useful tool for managing forest ecosystems to maintain forest sustainability and prevent forest disturbance.

The occurrence phases and enrichment mechanism of rare earth elements in cobalt-rich crusts from Marcus-Wake Seamounts

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.

The occurrence characteristics of oil in shales matrix from organic geochemical screening data and pore structure properties:An experimental study Author links open overlay panel

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.

Prediction and driving factors of forest fire occurrence in Jilin Province,China

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.

Persistent mixing bursts in the equatorial Pacific thermocline induced by persistent equatorial waves

A recent study by Liu et al.(2020)suggested that due to the saturation of equatorially trapped planetary waves with different dynamical types,temporal periods,meridional and baroclinic modes,complex layer structures of vertical velocity shear and hence turbulent mixing could frequently occur in the thermocline of the eastern equatorial Pacific.We investigated the occurrence of the interior turbulent mixing as indicated by shear instabilities,above the Equatorial Undercurrent(EUC)core at three equatorial sites along 140°W,170°W,and 165°E,respectively,based mainly on data from the Tropical Atmosphere and Ocean(TAO)mooring array.We found that turbulent mixing bursts persisted in the thermocline of all three sites.Specifically,the interior turbulent mixing layers(ITMLs)could occur in probability of approximately 68%,53%,and 48%at the three sites,respectively.The overall occurrence probability shows obvious and similar biannual variations at 140°W and 170°W,which is higher in boreal from late summer to winter and lower in spring.Vertically,the ITMLs are primarily located above the EUC core and prevail in deeper(shallower)layers from late summer to winter(spring).Most ITMLs(70%)lasted for hours to 3 days,and a few of them(15%)for more than 7 days.The thicknesses of ITMLs were concentrated between 15 and 55 m.At 165°E,the vertical distribution of ITML occurrence probability was different from that at 140°W and 170°W,as it did not show a preference for depths;the durations of ITMLs are short(also from hours to several days)and their thicknesses were between 5 and 25 m.These properties,particularly the high occurrence probability,and short durations demonstrated the persistence of thermocline mixing in the western to eastern equatorial Pacific thermocline and confirmed the generation mechanism by persistent equatorial waves as well.

Occurrence and Control of Main Pest Groups in Allium tuberosum Fields in Shijiazhuang

[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.

Multi-Scale Approach for Gold Targeting in Côte d’Ivoire Paleoproterozoic Rocks

The aim of this study is to contribute to better targeting of gold prospecting areas using geospatial information. To this end, 3 mining sites were selected for the study. They are: the Sénoufo belt (Barrick Gold mine), the Yaouré complex (Perseus Mining mine) and the South Fetêkro belt (Bonikro, Hiré and Agbaou mines). For this study, a multi-scale approach was carried out at regional, mine and microscopic levels. At the regional scale, a comparative analysis of 1:200,000 scale geological maps revealed that 3 main lithologies are regularly repeated on and around the various mining sites. These are: undifferentiated volcanics, metagranodiorites and metasiltites dominated by meta-arenites. Most of these lithologies are affected by undifferentiated faults generally oriented NE-SW, N-S, ENE-WSW and WNW-ESE. In addition, gold and manganese occurrences are present on all the sites studied. At the mine scale, radarsat-1 images processing indicate that the main mining sites are generally located near or at the intersection of lineaments-oriented NE-SW or N-S on the one hand and E-W or ENE-WSW or WNW-ESE or again NW-SE on the other. These mines are also located at the interface between zones of high and low lineament density. At the microscopic scale, petrographic studies of undifferentiated volcanic samples from the various sites indicate that they consist of andesites, meta-andesites and tuffs.

Occurrence Regularity and Comprehensive Prevention and Control Techniques of Sunflower Downy Mildew

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.

Integrated Prevention and Control Technology for Coffee Leaf Rust in Yunnan Province

This paper investigates the damage symptoms and occurrence regularity related to coffee leaf rust,and proposes a comprehensive prevention and control strategy grounded in the principle of prioritizing prevention and implementing integrated prevention and control.This strategy encompasses the cultivation of rust-resistant varieties,the implementation of agricultural practices,the application of chemical interventions,the utilization of hyperparasitic fungi,and the protection and utilization of natural enemies.The paper further outlines the necessary requirements for effective prevention and control,emphasizing the importance of enhancing responsibility implementation,fostering systematic prevention and control measures,enhancing guidance services,and increasing publicity and guidance.The aim is to offer technical guidance for the integrated prevention and control of coffee leaf rust in Yunnan Province.

Gold occurrence of Jiaojia gold mine in Shandong province

The microscopy and scanning electronic microscopy （SEM） were used to study the gold occurrence of Jiaojia gold mine, Shandong province. The results show that the gold-bearing minerals are composed of pyrite, chalcopyrite, gangue, sphalerite and galena. 77.12% of gold minerals are the sulphides and 22.88% are the gangues. The gold occurrence is composed of 60.28% fissure gold, 21.63% inclusion gold and 18.09% crystal fractured gold. The morphology of gold mineral is composed of sphere, triangle, rectangle, strip and erose. The Jiaojia gold mineral owns large grain size range from 3-5 μm to 100 μm. 1.5% of gold grains is more than 0.104 mm, 5.26% is 0.074-0.104 mm, 23.31% is 0.043-0.074 mm, 3.76% is 0.043-0.037 mm and 64.29% is less than 0.037 mm. The occurrence of gold mineral is composed of native gold, electrum, native silver, iron-bearing native silver, goldcuprid and acanthite. Electrum is the most important mineral, accounting for 71.56%. The average quality is 641.26‰ for gold and silver mineral.

Mineralogy and crystal chemistry of a low grade nickel laterite ore

To acquire understanding of Ni enrichment from laterite ore,the mineralogy and crystal chemistry of a low grade limonite type nickel laterite ore sample assaying 0.97% Ni from Indonesia were studied using optical microscopy,X-ray diffraction（XRD）,scanning electron microscopy（SEM） and electron probe microanalysis（EPMA）.According to EPMA results,the mineral includes 80% goethite（（Fe,Ni,Al）O（OH）） with 0.87% Ni,15% silicate minerals with lizardite（（Mg,Fe,Ni）3Si2O5（OH）） and olivine（（Mg,Fe,Ni）2SiO4）,and 1.19% Ni,and other minor phases,such as hematite,maghemite,chromite and quartz,and no Ni was detected.The mineralogy of the laterite ore indicates that due to the complicated association of the various phases and the variable distribution of Ni,this refractory laterite ore can not be upgraded by traditional physical beneficiation processes.

Law of Occurrence and the Damage of Main Diseases and Pests in Ligusticum chuanxiong Hort Field

[Objective]The aim was to provide scientific basis for the prevention and treatment of the main diseases and pests. [Method]The systematic investigation was carried out in the process of seedling and field cultivation of Ligusticum chuanxiong. [Result]The main diseases were root rot,Powdery mildew and Spot blight,while the main pests were Epinotia leucantha Meyrick,Prodenia litura Fabr.,Scarabaeoidea,Tetranychus cinnabarinus Boisduval and Delia platura Meigen. [Conclusion]The law of occurrence of main diseases and pests were confirmed.

Reasearch on Occurrence Rules of Asian Corn Borer Ostrinia furnacalis in the Field of Waxy Corn

[Objective] This program aimed at providing basis for timely and effective control of Asian corn borer Ostrinia furnacalis in waxy corn fields through investigations and researching on occurrence and damage characteristics of Ostrinia furnacalis in the main producing area of waxy corn of Shanxi Province.[Method] Attraction and collection of the adults,fixed-points and random investigations on eggs and larvae were the main methods in this research.[Result] Ostrinia furnacalis appeared in two generations per year in the field of waxy corns,the generations were basically nonoverlapping with significant interval.The peak period of the overwintering generation adults in the field of waxy corn was early to middle of June,peak period of the first generation adults was from early August to late August;peak period of the first generation eggs was from the end of early June to the binning of late June,the peak period of the second generation eggs was from the middle of early August to late August.Egg-laying performances of Ostrinia furnacalis on waxy corns in different growth period suggested that the temptation of waxy corns to egg-laying of Ostrinia furnacalis had gradually increased with the continuation of growth stages before the heading of waxy corns;while after the heading of waxy corns,the temptation of waxy corns to egg-laying of Ostrinia furnacalis had gradually reduced with the continuation of growth stages.The amount of eggs on waxy corns was more than eggs on normal corns with the same growth period and growth conditions.The first generation of Ostrinia furnacalis caused more serious damages than the second generation.The first generation larvae caused more serious damages on waxy corns with early sowing period than with middle sowing period,while the late sowing fields basically uninjured.The early sowing and middle sowing corns were damaged but lightly,due to the slight occurrence of the first generation larvae.The second generation larvae caused more serious damages in late sowing waxy corn field than in middle sowing waxy corn field.As the early sowing waxy corns were harvested before the beginning of damage peak period of the second generation larvae,they were basically uninjured or slightly damaged by the second generation larvae in general years.Because the second generation larvae were in large-scale occurrence,they had caused serious damages to late and later middle sowing waxy corns.Incidence of ear rot disease on the female ears of waxy corns was closely related to the damages of Ostrinia furnacalis on ears,which was higher on the ears infested by Ostrinia furnacalis.[Conclusion] Comprehensive control on the second generation of Ostrinia furnacalis in the mid and late sowing field of waxy corn should be strengthened.

Occurrence Regularity and Control Research of Apple Early Defoliation Disease in West Sichuan Plateau

[ Objective ] The research aimed to discuss the occurrence regularity of apple early defoliation disease and control effects of fungicides in west Sichuan plateau. [ Method ] Apple early defoliation disease in west Sichuan plateau was systematically investigated during 2009 and 2011, and the control effects of different fungicides during different spraying periods were studied. [ Result] The species of pathogen mainly was Marssonina ma/i （ P. Henn）, accounting for 32.5%, Phyl-losticta Pirina Sa accounted for 29.9%, and Alternaria mali Roberts accounted for 25.7%. The field fluctuation regularity was as follows ： the disease generally be- gan in the mid-May and ended in early and middle October with only one damage peak during the whole year, the fluctuation had positive correlation with rainfall （ R2 =0.891 8 ＊ ＊ ）. Control test showed that 40% flusilazole had the best control effect （86.5%）, which was best to apply after anthesis. [ Conclusion ] The paper provided theoretical basis for the effective control against apple early defoliation disease.

Advance in Rice Bacterial Leaf Streak Researches

Rice bacterial leaf streak,caused by Xanthomonas oryzae pv.oryzicola,is an important bacterial disease in rice-planting areas in South China and Southeast Asian countries.It occurs every year in local areas.This paper reviews the research advance in the occurrence and harms of rice bacterial leaf streak in China,classification of Xanthomonas oryzae and infection characteristics,pathogenic factors and pathogenicity of rice bacterial leaf streak and breeding of bacterial leaf streakresistance rice cultivars.Some issues involved in occurrence and control of rice bacterial leaf streak were presented,and the areas on which the future studies might be focused were discussed.

Research Progress of Occurrence and Comprehensive Control of Oriental Fruit Fly [Bactrocera dorsalis (Hendel)]

The paper summarizes the research progress of occurrence and comprehensive control of oriental fruit fly in the following aspects ： biological and ecological characteristics, assessment of the risk and suitability, dynamic monitoring and control index, and comprehensive control methods.

Identification and Control of Persimmon anthracnose

[ Objective] The study aimed to research the identification of Persimmon anthracnose and its controlling methods.[ Method ] The pathogen and characteristics, infection and occurrence law, damage symptoms of persimmon anthracnose were stated simply and the methods for con- trolling the disease were summed up. [ Result] The pathogen of Persimmon anthracnose was Gloeospor/um kaki Hod, belonging to Deuteromycotina. Germination and invasion of the conidia, sporulation and growth of mycelium all required high temperature, with the optimum temperature of 25 ℃ and the lethal temperature of 50 ℃ （10 min）. The occurrence strength of Persimmon anthracnose related with the factors including host, environment, culture circumstances, mainly doing harm to the fruits and branches. The occurrence of the disease could be controlled by such agricultur- al measures as cleaning the orchard, using the resistant varieties and planting the disease-free seedlings, adopting the balanced fertilization, improving the irrigation and drainage systems, conducting the dense planting and thin branches, building garden using the seedling that grafting on planted stock and raising the grafted parts of the stock. When the incidence was heavy, it needed to spray the fungicides or protective agent for the control of the Persimmon anthracnose. The fungicides should be mainly sprayed on the lesion of shoot, fruit surface and branches. [ Conclusion] The study provided the reference for the control of the Persimmon anthracnose.

Study on the Occurrence and Epidemic Regularity and Region Division of Rice Blast in Nanchong City

With the aim to improve the level of monitoring and warning as well as the comprehensive control of rice blast disease, and to feasibly reduce the disease threat in Nanchong City, the methods of GPS and GIS, systematical monitoring and field survey, rice blast resistance identification, physiologic races of rice blast monitoring, and meteorological data analysis were performed to study the occurrence and epidemic region division, precise demarcation and occurrence and epidemic regularity of rice blast in Nanchong City. This study first completed the epidemic region division and precise demarcation; first clarified the initial affection（beginning period） locations, occurrence characteristics, epidemic trends and characteristics; explicated the existence of four epidemic peak periods of rice blast in the field, where the damage areas of first peak period played a decisive role during the blast epidemic years; in late May, the cumulative occurrence areas and annual occurrence areas presented higher positive correlation with the correlation coefficient of 0.817;and established a prediction model of occurrence areas per year based on the disease field rate at the end of boot stages and the diseased plant rate at dough stages. The results of investigation on the impact factors investigation of blast disease in Nanchong in recent years suggested that the internal causes were the decrease or loss of blast resistance of the rice cultivars, as well as the increase of physiological races with strong resistance to rice blast and the emergence of new virulent physiologic varieties; the external causes were suitable temperature, too much rainy, and sunlight shortage. Between 2010 and 2015, the short-term forecast accuracy for rice blast in Nanchong was up to 100%, and medium-and long-term forecast accuracy was also up to 98% and 95%, respectively, which increased by 5-15% than that before 1997, thereby making the control effect of rice blast in Nanchong increased by 15-30%.