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1.
青土湖属于季风边缘区内陆河尾闾封闭湖泊,以其生态脆弱性和气候敏感性是古气候、古环境等全球变化环境研究的理想区域。降水是干旱区生态系统水循环的重要输入因子,研究降水氢氧同位素特征及水汽来源对全球气候变化背景下青土湖水资源管理具有重要的理论和实践意义。基于氢氧稳定同位素技术,通过分析青土湖5月～10月6个月21个大气降水氢氧同位素组成及与环境因子的关系,结合HYSPLIT模型模拟大气降水气团传输途径和过程,判定该地区水汽来源。结果表明:5月-10月大气降水氢氧稳定同位素关系的线性方程LMWL为δD=6. 67δ~(18)O-1. 01(n=21,R2=0. 95);大气降水的δ~(18)O变化范围为-16. 97‰～3.23‰,平均值为-5. 36‰。δD的变化范围为-118. 36‰～15. 63‰,平均值为-36. 82‰。过量氘(d-excess)介于-23. 64～21. 93‰,均值为6. 03‰,低于全球平均值(10‰)。降水δ~(18)O与降雨量显著相关,但温度效应不显著。受西风水汽、局地人工季节性湖面蒸发和亚洲季风的影响,青土湖大气降水水汽来源的季节性明显,夏季主要来源于西风环流、东南季风及局地蒸发,秋季来源于西伯利亚和蒙古的极地大陆气团。连续多年生态补水形成的人工季节性湖面蒸发成为夏季降水水汽来源之一,对改善湖区生态环境具有重要的意义。  相似文献   

2.
利用渭南大气降水δD和δ~(18)O实测值及相关的气象观测资料,分析了降水δD和δ~(18)O的特征及其变化与水汽来源的关系。结果表明:大气降水的同位素值变化幅度大,且呈现春季高、其他季节较低的季节变化;大气降水线的斜率低于全球大气降水线,截距接近且略高于全球大气降水线;大气降水的δ~(18)O与温度效应相关关系非常弱,温度效应不存在,存在降水量效应,但春冬季不显著,夏秋季较显著;大气气团来源的后向轨迹显示,冬半年降水水汽主要受控于西风环流,同时存在少有的局地蒸发作用,夏半年水汽来源于东南和西南海洋蒸发水汽,明确了氢氧稳定同位素存在季节变化的原因。  相似文献   

3.
氢氧稳定同位素是描述水循环过程的天然示踪剂,自来水是重要的生活用水,研究自来水中氢氧稳定同位素的变化特征有助于示踪城乡居民用水来源,为合理规划水资源调配提供参考。基于新疆352个自来水样品,对氢氧稳定同位素以及氘盈余(d=δ2H-8δ18O)的时空分布进行分析。结果表明：（1）新疆自来水水线为δ2H=7.67δ18O+10.54（R2=0.92）,δ2H月均值的变化范围为-105.57‰～-37.82‰,δ18O的月均值在-14.48‰～-6.67‰之间,d的月均值在1.89‰～24.38‰之间波动。（2）北疆和南疆的氢氧稳定同位素及氘盈余都存在季节变化,并且南疆的季节差异比北疆大。（3）利用BW模型对新疆自来水中氢氧稳定同位素的空间分布进行模拟,发现南疆氢氧稳定同位素值普遍高于北疆的同位素值,并且山区同位素值低于盆地的同位素值。  相似文献   

4.
《干旱区研究》2021,38(4):930-938
为了研究稳定同位素质量平衡法在寒旱区封闭型内陆湖泊水量平衡计算中的适用性,以内蒙古高原达里湖作为研究区域,基于流域水体样品中氢氧稳定同位素(δD、δ~(18)O)特征分析,讨论了δD、δ~(18)O对水体蒸发和补给来源的指示作用。结果表明:夏季达里湖水体氢氧稳定同位素值不断减小,其主要受到降水过程的影响;冬季结冰过程使得氢氧同位素在冰体中富集。达里湖湖水δ~(18)O-δD关系点落在了当地大气降水线的右下方,显示湖区水体蒸发最为强烈;部分河水和地下水δ~(18)O-δD关系点落在当地大气降水线左上方,显示当地大气降水并非其地下水的主要补给来源。利用稳定同位素质量平衡法对2018年达里湖蒸发量和地下水补给量进行估算,结果显示年蒸发量约为2.69×10~8m~3,全年地下水补给量约为1.65×10~8m~3。在考虑动力分馏和初始水体同位素组成的条件下,利用水体稳定同位素分馏过程中δD与剩余水体比例的关系,计算得到达里湖湖水蒸发损失量约为初始水体的41%～46%。  相似文献   

5.
本文研究了乌鲁木齐地区近17年(1986—2002)大气降水的氢氧同位素组成,提出了大气降水线方程为δD=7.21δ18O+4.50,并与全国及全球降水线方程进行对比,揭示了该降水线方程的特征。研究表明,乌鲁木齐水分来源复杂,主要是西风带输送的海洋水汽和局地的蒸发,大气降水的加权平均18O与月平均气温相关关系显著,与雨量效应(降水量效应)较相关,降水中温度效应明显,且在一定时期很大程度上其影响掩盖了雨量效应。乌鲁木齐降水中δ18O的季节变化与温度的季节变化几乎一致,温度是制约降水中稳定同位素变化的主要影响因子。  相似文献   

6.
大气降水中氢氧稳定同位素包含着水循环演化过程中的历史信息,对揭示水资源的形成及演化机制具有重要的意义。文中根据包头站大气降水中稳定同位素和气象资料,分析了包头地区(1986-1992年)大气降水的氢氧稳定同位素的变化特征及其与气温和降水之间的关系,发现该区氘盈余值(d)具有冬季高夏季低的特点,且d值接近全球大部分地区降水的d值(10‰)。该区大气降水中δ18O值具有夏季高冬季低,δ18O的温度效应显著,而降水量效应只在夏半年(4-9月)间显著。同时提出了包头地区当地大气降水线方程为δD=6.4δ18O-4.07,与全国及全球降水线方程相比,反映出干旱的气候特征。  相似文献   

7.
全球气候变暖加速了区域水循环，改变了水汽的传输路径，了解不同等级降雨稳定同位素特征及水汽来源为水资源的利用及旱涝灾害的防治提供依据。基于2018—2020年夏半年（5—10月）采集的银川平原降雨样品，研究不同等级降雨中氢氧稳定同位素的变化特征及其二次蒸发效应，并利用后向轨迹模型及水汽通量等方法分析降雨的水汽来源及潜在蒸发源区。结果表明：银川平原夏半年不同等级降雨稳定同位素随着降雨等级的增加而偏负，小雨氘盈余（d-excess）值偏负而中雨和大雨偏正，大气降水线斜率和截距随着雨量级的增加呈现出递减的规律。二次蒸发作用的强弱随气温升高而增大，随降雨量、相对湿度和雨滴直径增大而减弱。西风水汽为银川平原夏半年降雨的主控水汽，同时小雨、中雨、大雨还分别受到陆地蒸发水汽、大西洋水汽及太平洋水汽的影响。潜在蒸发源区对小雨影响较大，主要位于研究区周边及北部、南部和东南部地区；中雨潜在蒸发源区主要分布在研究区周边地区及其西北部和东南部；大雨主要分布在研究区周边及东南部地区。  相似文献   

8.
氢氧稳定同位素指示的呼和浩特地区土壤水的补给特征   总被引：1，自引：0，他引：1  
土壤水中的氢氧稳定同位素特征包含了水在包气带中的迁移信息,因此,分析土壤水中的氢氧稳定同位素的变化特征可以追踪土壤水的迁移过程.文中主要对呼和浩特地区西南部两个孔的包气带土壤剖面中氢氧稳定同位素随深度的变化特征进行了分析,并对呼和浩特地区降水、土壤水和地下水之间的同位素组成进行了比较.结果表明:该区土壤表层的水中的δ2H和δ18O受到降水中的δ2H和δ18O的直接影响,同时受到蒸发作用的影响,同位素值产生富集,之后变化幅度逐渐减小,逐渐接近地下水中的同位素值,显示出土壤底部的水分与地下水的交换比较活跃;通过对比该区降水、土壤水和地下水的同位素值,发现该区土壤水的补给来源主要为降水,且降水的补给为季节性补给,补给季节主要是秋季.  相似文献   

9.
滹沱河上游区地表水和地下水同位素特征   总被引：2，自引：0，他引：2  
在滹沱河上游区采集了河水、地下水、泉水、水库水样品,分析了各类水的氢、氧、氮同位素和化学特征,并将氢氧稳定同位素与平原区大气降水进行了对比,分析了沿流程的变化,识别了硝酸盐来源。结果表明:滹沱河源区河水、地下水和泉水与平原区大气降水的同位素组成差别明显;滹沱河水进入水库以后,水库水受到明显的蒸发浓缩作用,也可区别于平原区大气降水;水样的NO3-含量变化在1.68~87.4 mg/L之间,大部分样品的1δ5N值大于8‰,指示水中NO3-来自污水或粪便。  相似文献   

10.
《干旱区研究》2021,38(5):1263-1273
利用喀什河流域山区2017-07—2018-06大气降水同位素数据,以及流域山区温度、降水气象资料,分析了降水中δ18O、δD和氘盈余(d-excess)变化特征,讨论了δ18O与气温、降水量的关系,通过利用HYSPLI模型追踪分析流域山区大气降水的水汽来源。结果表明:(1)流域内降水中δ18O季节变化明显,夏季δ18O同位素富集,冬季δ18O同位素贫化。(2)不同降水类型中δ18O、δD的关系差异明显,夏季δD蒸发分馏大于δ18O、降雨大气降水线斜率及截距较小;冬季δD蒸发分馏明显减弱,降雪大气降水线斜率及截距较大。(3)流域内大气降水同位素存在明显的温度效应,但是降水量效应不显著。(4)流域内大气降水水汽主要来源于大西洋,受水汽远距离输送,途中加入较多二次蒸发水汽的影响,氘盈余值(d-excess)整体上偏大,但是2月氘盈余偏低,与受北极气团源地温度低、空气湿度大、水汽输送路径短影响有关。(5)该流域夏季降水主要来源于西风环流和局地再循环水汽,冬季则受西风环流和北极气团共同影响,大西洋水汽形成的降水占研究区总降水量的68.6%,局地再循环水汽占17.1%,北冰洋水汽形成的降水占研究区总降水量的14.3%。  相似文献   

11.
Fifteen species of dermestid beetles were recorded at ‘Evolution Canyon’ (EC), Lower Nahal Oren, Mt. Carmel, Israel. They represent ~35% of known Israeli dermestid species. The following three species were recorded for the first time in Israel:Trogoderma svriaca Dalla Torre, 1911;Ctesias svriaca Ganglbauer, 1904; andAnthrenus (s.str.) jordaniens Pic, 1934. Adults of 13 species were collected on the more solar radiated, warmer and climatically more fluctuating south-facing slope (SFS); ten species were collected on the opposite, north-facing slope (NFS), which was cooler and climatically more stable. The abundance of adult dermestid beetles was 1.9 times higher on the SFS than on the NFS (86 and 47, respectively). Species richness and abundance distribution at EC (three collecting stations on each slope and one at the valley bottom) were significantly negatively correlated with the plant cover that consisted of trees and bushes (Spearmanr s ,P=0.007 and 0.039, respectively) and perennials (Spearmanr s ,P=0.039 and 0.077, respectively), indicating that non-woody plants were preferred by adult dermestid beetles.  相似文献   

12.
We first discuss the diversity of fruit fly (Diptera: Tephritidae) parasitoids (Hymenoptera) of the Neotropics. Even though the emphasis is on Anastrepha parasitoids, we also review all the information available on parasitoids attacking flies in the genera Ceratitis, Rhagoletis, Rhagoletotrypeta, Toxotrypana and Zonosemata. We center our analysis in parasitoid guilds, parasitoid assemblage size and fly host profiles. We also discuss distribution patterns and the taxonomic status of all known Anastrepha parasitoids. We follow by providing a historical overview of biological control of pestiferous tephritids in Latin American and Florida (U.S.A.) and by analyzing the success or failure of classical and augmentative biological control programs implemented to date in these regions. We also discuss the lack of success of introductions of exotic fruit fly parasitoids in various Latin American countries. We finish by discussing the most pressing needs related to fruit fly biological control (classical, augmentative, and conservation modalities) in areas of the Neotropics where fruit fly populations severely restrict the development of commercial fruit growing. We also address the need for much more intensive research on the bioecology of native fruit fly parasitoids.  相似文献   

13.
Molecular diagnostic techniques have been developed to differentiate the Ascochyta pathogens that infect cool season food and feed legumes, as well as to improve the sensitivity of detecting latent infection in plant tissues. A seed sampling technique was developed to detect a 1% level of infection by Ascochyta rabiei in commercial chickpea seed. The Ascochyta pathogens were shown to be genetically diverse in countries where the pathogen and host have coexisted for a long time. However, where the pathogen was recently introduced, such as A. rabiei to Australia, the level of diversity remained relatively low, even as the pathogen spread to all chickpea-growing areas. Pathogenic variability of A. rabiei and Ascochyta pinodes pathogens in chickpea and field pea respectively, appears to be quantitative, where measures of disease severity were based on aggressiveness (quantitative level of infection) rather than on true qualitative virulence. In contrast, qualitative differences in pathogenicity in lentil and faba bean genotypes indicated the existence of pathotypes of Ascochyta lentis and Ascochyta fabae. Therefore, reports of pathotype discrimination based on quantitative differences in pathogenicity in a set of specific genotypes is questionable for several of the ascochyta-legume pathosystems such as A. rabiei and A. pinodes. This is not surprising since host resistance to these pathogens has been reported to be mainly quantitative, making it difficult for the pathogen to overcome specific resistance genes and form pathotypes. For robust pathogenicity assessment, there needs to be consistency in selection of differential host genotypes, screening conditions and disease evaluation techniques for each of the Ascochyta sp. in legume-growing countries throughout the world. Nevertheless, knowledge of pathotype diversity and aggressiveness within populations is important in the selection of resistant genotypes.  相似文献   

14.
Recent data on the epidemiology of the common mycotoxigenic species of Fusarium, Alternaria, Aspergillus and Penicillium in infected or colonized plants, and in stored or processed plant products from the Mediterranean area are reviewed. Emphasis is placed on the toxigenicity of the causal fungal species and the natural occurrence of well known mycotoxins (aflatoxins, ochratoxins, fumonisins, trichothecenes, zearalenone, patulin, Alternaria-toxins and moniliformin), as well as some more recently described compounds (fusaproliferin, beauvericin) whose toxigenic potential is not yet well understood. Several Fusarium species reported from throughout the Mediterranean area are responsible of the formation of mycotoxins in infected plants and in plant products, including: Fusarium graminearum, F. culmorum, F. cerealis, F. avenaceum, F. sporotrichioides and F. poae, which produce deoxynivalenol, nivalenol, fusarenone, zearalenone, moniliformin, and T-2 toxin derivatives in wheat and other small grains affected by head blight or scab, and in maize affected by red ear rot. Moreover, strains of F. verticillioides, F. proliferatum, and F. subglutinans, that form fumonisins, beauvericin, fusaproliferin, and moniliformin, are commonly associated with maize affected by ear rot. Fumonisins, were also associated with Fusarium crown and root rot of asparagus and Fusarium endosepsis of figs, caused primarily by F. proliferatum. Toxigenic A. alternata strains and associated tenuazonic acid and alternariols were commonly found in black mould of tomato, black rot of olive and citrus, black point of small cereals, and black mould of several vegetables. Toxigenic strains of A. carbonarius and ochratoxin A were often found associated with black rot of grapes, whereas toxigenic strains of A. flavus and/or P. verrucosum, forming aflatoxins and ochratoxin A, respectively, were found in moulded plant products from small cereals, peanuts, figs, pea, oilseed rape, sunflower seeds, sesame seeds, pistachios, and almonds. Finally, toxigenic strains of P. expansum and patulin were frequently found in apple, pear and other fresh fruits affected by blue mould rot, as well as in derived juices and jams.  相似文献   

15.
《干旱区科学》2014,(6):782-782
正Journal of Arid Land(JAL)is an international journal(ISSN 1674-6767;CN 65-1278/K)for the natural sciences,sponsored by the Xinjiang Institute of Ecology and Geography,Chinese Academy of Sciences and Science Press.It is published by Science Press and Springer-Verlag Berlin Heidelberg bimonthly.JAL publishes original,innovative,and integrative research from arid and semiarid regions,ad  相似文献   

16.
The genera ofMicrogaster Latreille 1804 andHygroplitis Thomson 1895 from China are presented systematically in this paper. Thirty-two species ofMicrogaster and three species ofHygroplitis are known in China. Diagnosis, character variation, distribution and host of each species among the two genera are presented, including its host and distribution. Keys to the species ofMicrogaster andHygroplitis are given. http://www.phytoparasitica.org posting Dec. 19, 2006.  相似文献   

17.
Plant Viruses Transmitted by Whiteflies   总被引：18，自引：0，他引：18  
One-hundred and fourteen virus species are transmitted by whiteflies (family Aleyrodidae). Bemisia tabaci transmits 111 of these species while Trialeurodes vaporariorum and T. abutilonia transmit three species each. B. tabaci and T. vaporariorum are present in the European–Mediterranean region, though the former is restricted in its distribution. Of the whitefly-transmitted virus species, 90% belong to the Begomovirus genus, 6% to the Crinivirus genus and the remaining 4% are in the Closterovirus, Ipomovirus or Carlavirus genera. Other named, whitefly-transmitted viruses that have not yet been ranked as species are also documented. The names, abbreviations and synonyms of the whitefly-transmitted viruses are presented in tabulated form together with details of their whitefly vectors, natural hosts and distribution. Entries are also annotated with references. Whitefly-transmitted viruses affecting plants in the European–Mediterranean region have been highlighted in the text.  相似文献   

18.
Liriomyza cicerina (Diptera: Agromyzidae) is an important pest on chickpea in Turkey. The objective of this study was to determine the parasitoids and rates of parasitism ofL. cicerina on chickpea (Cicer arietinum L.) during the 2005 and 2006 seasons in ?anl?urfa province, Turkey. Leaves with mines were sampled weekly and kept in the laboratory to observe and count emerging leafminer and parasitoid adults. Eight parasitoid species were collected: the braconidsOpius monilicornis Fischer andOpius tersus Foerster and the eulophidsDiaulinopsis arenaria (Erdös) andNeochrysocharis formosa (Westwood), which occurred in both the winter and summer seasons;Diglyphus crassinervis Erdös,Neochrysocharis ambitiosa Hansson,Neochrysocharis sericea (Erdös) andPediobius metallicus (Nees), which occurred only in the summer growing areas.Diaulinopsis arenaria was the predominant parasitoid with 4–7.7% parasitism rate whileN. ambitiosa andO. monilicornis were the second and third most predominant species. The results of these trials show that sinceDia. arenaria occurred throughout every season, it could potentially be used for control of the leafminerL. cicerina.  相似文献   

19.
Systematic information on the quantitative impact of Z ygogramma bicolorata on the biology of P arthenium hysterophorus is crucial as the seeds of this weed continue to germinate from the accumulated soil seed bank throughout the year in the form of different germinating flushes, while the activity of the beetle ceases during winter as it enters diapause. Therefore, plant–herbivore interactions need to be explored to develop predictions of the overall impact of the introduced beetle on the weed. The findings revealed that defoliation by Z . bicolorata had a significant impact on the plant height, density and flower production in flushes F 3, F 4 and F 5, but not in F 1 and F 2 that exhibited longer periodicity, profuse branching, a longer flowering period and maximum flower production and contributed mostly to the existing seed soil bank. Therefore, total depletion of the existing soil seed bank was not possible. Consequently, the effect of augmentative field releases of laboratory‐reared beetles was explored on F 1 and F 2 in February for three consecutive years (2011–2013). Before initiating the trial, random soil samples were taken from the plots that were assigned to the paired treatments (i.e. with the beetle and without the beetle [insecticide‐treated]) and it was found that the seed bank in those samples did not differ. The single release of Z . bicolorata adults at five per plant at the six‐leaf stage significantly reduced the soil seed bank, compared to without the biocontrol agent, irrespective of the flushes at the end of the season.  相似文献   

20.
Solacol®, a formulation of the antibiotic validamycin, at 0.33% in 2% malt extract agar, reduced the spread of fungi on dilution plates drastically and allowed twice as much incubation time before subculturing; this resulted in an elevated number of species isolated. Using pure cultures of 62 common soil fungi, it was shown that all fast-growing species (exceptPythium ultimum) were efficiently inhibited but not completely suppressed. Inhibition was comparable to that by 0.5% oxgall, though, while this substance completely suppressed several species, Solacol very strongly inhibited onlyGaeumannomyces graminis, Gerlachia nivalis, Harzia acremonioides, Verticillium biguttatum andRhizoctonia solani. In a further experiment each separate constituent of Solacol was tested against 22 fungi at equivalent concentrations. Validamycin strongly inhibitedChaetomium globosum and two Basidiomycetes, though hardly more than the non-ionic detergent which mainly inhibited the other fungi. A few species were, however, more inhibited by Solacol than by the detergent alone. Solacol at 0.33% is a suitable aid in dilution plating of soil fungi, by increasing the number of colonies and species observed.Samenvatting Solacol®, een formulering van het antibioticum validamycine, remde de groei van schimmels in verdunningsplaten met een concentratie van 0.33% in 2% moutagar en maakte het mogelijk de periode tot afenten met een factor 2 te verlengen; daardoor was het aantal geïsoleerde soorten duidelijk toegenomen. Met reincultures van 62 algemene grondschimmelsoorten werd aangetoond, dat alle snelgroeiende soorten (met uitzondering vanPythium ultimum) voldoende geremd, maar niet volkomen onderdrukt werden. Het remmingspercentage was vergelijkbaar met dat van 0.5% ossegal, hoewel dit laatste sommige soorten volkomen onderdrukte; Solacol remde alleenGaeumannomyces graminis, Gerlachia nivalis, Harzia acremonioides, Verticillium biguttatum enRhizoctonia solani zeer sterk. In een volgend experiment werden de componenten van Solacol t.o.v. 22 fungi apart getoetst in concentraties equivalent aan 0.33% Solacol. Validamycine remde alleenChaetomium globosum en twee basidiomyceten behoorlijk, maar nauwelijks meer dan de niet-ionische uitvloeier, die in hoofdzaak de overige remeffecten veroorzaakte. Enkele soorten werden echter door het complete Solacol veel sterker geremd dan door de uitvloeier alleen. Solacol in een verdunning van 0,33% wordt aanbevolen bij verdunningsplaten voor het isoleren van grondschimmels ten einde het aantal kolonies en soorten te verhogen.  相似文献   

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