乌鲁木齐河源1号冰川雪坑δ^18O剖面特征与气候的关系

2004年10月至2005年9月,在天山乌鲁木齐河源1号冰川积累区采集了16组雪坑样品。利用雪坑中δ18O资料,分析干季和湿季冰川雪坑δ18O剖面特征与气候的关系。结果表明：δ18 O变化主要集中在雪坑上部,在距底部附加冰130 cm以下变化不大,且维持在较高值。其中,干季雪层剖面上部基本反映了积累期温度的变化,湿季不...     

西藏日喀则末次冰期风成黄土粒度分析及其意义

通过对西藏日喀则市大竹卡乡风成黄土剖面样品的粒度测试分析,划分出六个气候阶段,显示67.0±7.2kaB.P-10.4±1.6 kaB.P间经历了温暖湿润-干燥多风-温暖干燥-干燥多风-湿干偏湿-温暖湿润环境的变化。该地区的黄土是半干旱-半湿润气候条件下形成的砂黄土,粒度较黄土高原的黄土要粗,表明当时受行星风系及高原隆升的影响,冰期的温度整体较低,雅鲁藏布江中部流域受西南季风的影响减小,规模小的温暖湿润波动不能对气候产生影响。因此,本区地层中的记录信息较黄土高原简单,气候向干冷化发展。     

Characteristics and hazards of different snow avalanche types in a continental snow climate region in the Central Tianshan Mountains

Snow avalanches are a common natural hazard in many countries with seasonally snow-covered mountains.The avalanche hazard varies with snow avalanche type in different snow climate regions and at different times.The ability to understand the characteristics of avalanche activity and hazards of different snow avalanche types is a prerequisite for improving avalanche disaster management in the mid-altitude region of the Central Tianshan Mountains.In this study,we collected data related to avalanche,snowpack,and meteorology during four snow seasons(from 2015 to 2019),and analysed the characteristics and hazards of different types of avalanches.The snow climate of the mid-altitude region of the Central Tianshan Mountains was examined using a snow climate classification scheme,and the results showed that the mountain range has a continental snow climate.To quantify the hazards of different types of avalanches and describe their situation over time in the continental snow climate region,this study used the avalanche hazard degree to assess the hazards of four types of avalanches,i.e.,full-depth dry snow avalanches,full-depth wet snow avalanches,surface-layer dry snow avalanches,and surface-layer wet snow avalanches.The results indicated that surface-layer dry snow avalanches were characterized by large sizes and high release frequencies,which made them having the highest avalanche hazard degree in the Central Tianshan Mountains with a continental snow climate.The overall avalanche hazard showed a single peak pattern over time during the snow season,and the greatest hazard occurred in the second half of February when the snowpack was deep and the temperature increased.This study can help the disaster and emergency management departments rationally arrange avalanche relief resources and develop avalanche prevention strategies.     

Estimation of soybean rust uredospore terminal velocity,dry deposition,and the wet deposition associated with rainfall

Using models from atmospheric chemistry and physics, this study examined the wet deposition of single uredospores of soybean rust caused by Phakopsora pachyrhizi associated with rainfall and its importance compared with dry deposition. First, a measurement of the terminal velocity of freshly collected P. pachyrhizi uredospores was conducted in Nanning, China. The observed terminal velocities associated with different sizes of the uredospore clumps were fitted by negative exponential models. The average terminal velocity of single uredospores (0.0187 m s⁻¹) determined by the fitted models was used to estimate the dry deposition. The wet deposition of single uredospores associated with different rainfall rates was determined numerically using coupled models, in which raindrop capture efficiency of uredospores was based on Slinn’s semi-empirical model. The results showed that at a rainfall rate of 0.5 mm h⁻¹, wet deposition can remove 50% of the single uredospores in the air within 1 h. If the rainfall rate is 5 mm h⁻¹, 10 min is sufficient to remove 50% of the uredospores. The dry deposition of the single uredospores was estimated with simplified scenarios: i.e., assuming the uredospore cloud was continuously from 1,000 to 2,000 m in height above a field with a uniform concentration. In the first 16 h, almost no uredospores reached the ground, while the wet deposition caused by 2 mm h⁻¹ rainfall within 30 min was even much greater than dry deposition of 24 h duration. The comparisons indicated that the wet deposition of soybean rust uredospores was much more efficient than the dry deposition.     

新疆呼图壁河径流时间序列分析

基于呼图壁河石门水文站1956—2011年的年径流数据,采用Morlet小波分析和R/S分析方法,对新疆呼图壁河流域径流周期、变化特征和未来趋势进行分析和预测。研究结果表明:(1)通过对呼图壁河1956—2011年径流量的分析发现,径流时间序列存在5 a、10 a、18 a和28 a左右的震荡周期,18 a尺度震荡周期最强,其次是28a尺度。18 a时间尺度上的震荡在56 a研究时段内均较强,且存在4个丰水期和5个枯水期;28 a震荡周期在56 a尺度时段内相对较强,存在3个丰水期和3个枯水期,目前处于偏丰期;(2)利用R/S分析呼图壁河径流量序列,Hurst指数为0.6442,存在明显的赫斯特现象,这就意味着未来一段时间的径流量与过去具有同样的增加趋势。     

Variability of hard parts of opisthaptor of two species of Gyrodactylus nordmann, 1832 (Monogenoidea) from Phoxinus Phoxinus (L.).

The morphological and metrical variability of hard parts of opisthaptor was studied in the representatives of local populations of Gyrodactylus aphyae Malmberg, 1957 and G. macronychus Malmberg, 1957. The changes within the range of variability, which were observed during the year, correspond to regular and periodical changes in the environmental temperatures. The hard parts of opisthaptor were much smaller in specimens occurring during warm seasons than in specimens occurring during cold seasons. The temperature of about 8 degrees C forms a boundary between warm and cold seasons. The author assumes that similarly as G. aphyae and G. macronychus also other members of the genus Gyrodactylus living in climatic zones with regular change of seasons will react similarly on the annual variation in the environmental temperatures.     

Seasonal activity of EPTC for Cyperus rotundus L. control in a tropical climate*

Four experiments were conducted at six week intervals to determine the seasonal activity and persistence of soil-incorporated EPTC (5-ethyl N,N-dipropyl(thiocarbamate)) for Cyperus rotundus L. control and tolerance of okra (Hibiscus esculentus L.), cucumber (Cucumis sativus L.), lettuce (Lactuca sativa L.), red beet (Beta vulgaris L.) and carrot (Daucus carota L.) during the dry and wet seasons in Viçosa, Brazil. Satisfactory control of C. rotundus was obtained at 2 kg/ha EPTC during the dry season and 4 kg/ha or more during the wet season. Only red beet and carrot tolerated these doses of EPTC when the crops were planted five days after application. However, selective control of C. rotundus was obtained when the planting date of lettuce was delayed for three or six weeks after EPTC application. EPTC controlled C. rotundus at half the dose that was required to control three species of annual grass that germinated near the soil surface. EPTC persisted longer when applied to air dry soil and incorporated with a rototiller than when incorporated into moist or wet soil.     

基于支持向量机的石羊河流域径流模拟适用性评价

基于VC维和结构化风险最小理论的支持向量机方法因具有较好的学习和泛化能力而在预测预报领域得到广泛的应用。文中选取当月平均降水量、上月平均降水量以及当月平均相对湿度、平均最高气温和平均最低气温五个预报因子,采用Gridsearch算法优化参数,建立了基于支持向量机的月径流预报模型,并将其应用于石羊河流域八个子流域,定量分析其适用性。结果表明:模型在率定期和验证期模拟的平均Nash-Sutcliffe效率系数分别为0.831和0.806,相对误差分别在6%和5%以内;除个别峰值模拟较小之外,流量序列整体模拟效果较好;模型在丰水时段模拟值小于实测值,枯水时段模拟值大于实测值,在平水时段和枯水时段的模拟效果要优于丰水月份。因此,支持向量机模型在石羊河流域具有较好的适用性,可用于该流域的中长期水文预报。     

The climatic and hydrological changes and environmental responses recorded in lake sediments of Xinjiang, China

Based on the analyses of environmental proxy data in lake sediments and instrumental records of Xinjiang in northwest China,the Holocene climate and hydrological variability and its environmental responses were studied in different time scales and regions. The results showed that the Holocene climate variability had obvious differences between the north and south of Xinjiang. In northern Xinjiang,the Holocene climate was dry in the early period,humid in the middle period,and then changed to dry in the late period. However,the climate transition times were not consistent in different regions. In southern Xinjiang,although there were many different types of climate change patterns inferred from different catchments,the warm and wet climate was recorded in most lake sediments in the middle Holocene. According to comparisons of some millennium scale records in lake sediments,the climate was warm and dry in the past 100 years. It can be concluded the climate showed a trend of aridity in Holocene. Especially in recent 50 years,the lake area has been shrinking rapidly because of the population growth and social economic development,which brings some environmental problems. Lake level and area changes were sensitively affected by the climate variation in geological history of Xinjiang and the lake level will continue to shrink because of the drought climate and strengthened human activities.     

Phylogenetic and Pathotypic Analysis of Rice Bacterial Blight Race 3

Eight Philippine races of Xanthomonas oryzae pv. oryzae have been identified based on virulence phenotypes observed on a set of five differential varieties. One of these, Race 3, was found to consist of two phylogenetically distinct lineages based on DNA fingerprinting analysis. To determine, if the two lineages could be differentiated based on host-specificity, 186 strains of Race 3 were analyzed with additional fingerprints and 76 selected isolates with additional differential rice varieties. The strains were separated into 36 haplotypes clustering in three groups (IS1113-B, -C, and -G) at the 75% similarity level. Isolates varied in their reaction to a rice line carrying the resistance gene Xa7, however, the variability was not consistent within lineage. Aggressiveness of isolates belonging to lineage IS1113-B and -G was significantly greater when tested during the dry season than when tested during the wet season. However, no such differences were evident for isolates from lineage IS1113-C, indicating that environmental effects presumably light and temperature are genotype-specific.     

Seventh British Insecticide and Fungicide Conference,Brighton, November 1973

Abstract

A field experiment was conducted during the wet seasons of 1980 and 1981 to find out the relative influence of weed control and applied nitrogen on performance of transplanted rice and nutrients uptake by rice and weeds. Propanil and thiobencarb, each at 2.0 kg a.i/ha, were found comparable to two hand weedings in increasing grain yield of rice and minimizing dry matter of weeds. The mean grain yield was increased by 28.06% while dry matter of weeds reduced by 84.04% over unweeded control. Application of nitrogen from 0 to 75 kg N/ha increased grain yield to the tune of 1631 kg/ha. Remarkable increase in grain yield was noticed when weed control treatments were associated with application of nitrogen. Higher uptake of N, P and K by crop and lower removal of same nutrients by weeds were observed in herbicides and hand weedings than unweeded control. N, P and K in the order of 11.49, 1.71 and 12.40 kg/ha respectively could be saved through weed control in transplanted rice.     

Effects of interrupted wet periods and different temperatures on the development of ascochyta blight caused by Mycosphaerella pinodes on pea (Pisum sativum) seedlings

The effect of interrupted wet periods on pycnidiospores of Mycosphaerella pinodes was studied by assessing spore viability, infection and disease development on pea seedlings. Pycnidiospores survived dry periods of up to 21 days after inoculation. Rewetting restored the infection capacity of the pycnidiospore, resulting in high levels of disease. The effects of wet–dry–wet cycles depended on when the dry period occurred during the infection process. No disease symptoms appeared when dry periods occurred during germination. A low level of disease occurred after rewetting in high relative humidity if the interruption of the wet period was long. However, a wet period resulting in leaf wetness after a dry period gave similar levels of infection to those achieved with a continuous wet period. Pycnidiospores formed appressoria but hyphae did not penetrate if a 6–12 h wet period preceded the dry period, and only a few flecks appeared during the dry period. Coalescent necrosis occurred when the dry period followed penetration. The disease was severe in each case when plants were returned to wet conditions after a period of dryness. Lesion development depended on the duration of the initial wet period, and the characteristics (temperature and duration) of both the dry period and the final wet period.     

渭河关中段生态基流量估算研究

文中回顾了国内外生态基流的研究现状及主要计算方法,结合渭河流域的实际情况,选择Ten-nant法、90%保证率最枯月平均流量法和最枯月平均流量多年平均值法三种方法分别对渭河流域林家村、咸阳和华县三个断面不同水平年下的生态基流量进行了估算。结果表明：Tennant法在丰、平、枯水年三种水平年下估算的生态基流量较为合理,林...     

Dynamics of groundwater recharge near a semi-arid Mediterranean intermittent stream under wet and normal climate conditions

In arid and semi-arid stream-dominated systems, the temporal variability in groundwater recharge has not been widely addressed. Various questions remain about the sources of groundwater recharge, its patterns, and the appropriate measuring techniques. Hence, the main objective of the present study was to assess the changes that might affect the pattern of groundwater recharge under wetter than normal surface water availability. Therefore, the groundwater depth was monitored near a semi-arid Mediterranean intermittent stream on the piedmont of the High Atlas Mountains in the mountain catchment of the Wadi Rheraya over two hydrological years (2014-2016) with different climate conditions: extreme wet and normal conditions. Groundwater recharge was assessed using the episodic master recession algorithm. During the two years, the pattern of groundwater recharge was dominated by episodic events and by a high seasonality from wet seasons to dry seasons. In the wet year (2014-2015), the highest groundwater recharge was recorded following an extreme flood, which deeply replenished groundwater. Furthermore, an exceptional steady state of the groundwater depth was induced by a steady groundwater recharge rate. For several groundwater recharge events, the assessed recharge had multiple sources, mainly from streamflow at the local scale, but possibly from precipitation, underflow, deep percolation or irrigation return from the upstream part of the catchment. Local recharge by streamflow was likely to be short-lived, and lateral recharge was likely to last longer. Consequently, the episodic master recession algorithm estimated the total groundwater recharge that could encompass various sources. In the future, more studies and multidisciplinary approaches should be carried out to partition these sources and determine their specific contributions. In semi-arid stream-dominated systems, different groundwater recharge patterns induced by extreme hydrological events (e.g., wet events) and various potential sources of groundwater recharge should be considered when assessing and predicting groundwater recharge.     

Spinosad as an effective larvicide for control of Aedes albopictus and Aedes aegypti, vectors of dengue in southern Mexico

BACKGROUND: Field trials were conducted during the wet and dry seasons in periurban and semi‐rural cemeteries in southern Mexico to determine the efficacy of a suspension concentrate formulation of spinosad (Tracer 480SC) on the inhibition of development of Aedes albopictus L. and Ae. aegypti Skuse. For this, oviposition traps were treated with spinosad (1 or 5 mg L^?1), Bacillus thuringiensis israelensis (Bti, VectoBac 12AS), a sustained release formulation of temephos and a water control. RESULTS: Ae. albopictus was subordinate to Ae. aegypti during the dry season, but became dominant or codominant during the wet season at both sites. The two species could not be differentiated in field counts on oviposition traps. Mean numbers of larvae + pupae of Aedes spp. in Bti‐treated containers were similar to the control at both sites during both seasons. The duration of complete absence of aquatic stages varied from 5 to 13 weeks for the spinosad treatments and from 6 to 9 weeks for the temephos treatment, depending on site, season and product concentration. Predatory Toxorhynchites theobaldi Dyar and Knab suffered low mortality in control and Bti treatments, but high mortality in spinosad and temephos treatments. Egg counts and percentage of egg hatch of Aedes spp. increased significantly between the dry and wet seasons, but significant treatment differences were not detected. CONCLUSION: Temephos granules and a suspension concentrate formulation of spinosad were both highly effective larvicides against Ae. aegypti and Ae. albopictus. These compounds merit detailed evaluation for inclusion in integrated control programs targeted at Ae. aegypti and Ae. albopictus in regions where they represent important vectors of human diseases. Copyright © 2010 Society of Chemical Industry     

A PRELIMINARY INVESTIGATION OF THE PENETRATION AND TRANSLOCATION OF 2,4,5-T IN SOME TROPICAL TREES

Summary The relative mobility of ¹⁴C-labelled 2,4,5-T in the trunks of four different tree species was tested in dry and wet seasons, with the intention of observing the difference in translocation pattern between the susceptible ( Piptadeniastrum africanum, Celtis mildbraedii ) and the tolerant ( Xylopia quintasii, Ricinodendron heudelotii ) species, Nine trees were analysed altogether. There was a consistent pattern of adsorption and retention of the arboricide by the phloem of the four sensitive trees and downward movement of the material was marked, but in the five resistant trees the chemical was distributed upward to a greater extent in the transpiration stream. Thus in the susceptible species where there is more phloem movement the chcmical is least mobile, whereas in the tolerant ones where the chemical moves in the xylem, it is most mobile. Both types of investigation (longitudinal and radial) indicate that the killing action in the sensitive species is due to the retention of the chemical by the phloem, and that its failure to kill the tolerant trees is due to the upward movement in the transpiration stream via the xylem.     

末次冰消期以来古猪野泽湖相地层沉积学及湖面波动历史

本文选取古猪野泽地区的青土湖剖面、西渠剖面、沙坑井剖面、九坨墚剖面作为研究对象,通过广泛野外地貌考察、剖面地层对比,作者认为古猪野泽最高湖面的海拔高度为1313~1315m,气候变化自末次冰期以来共经历了2个成湖期(13000~9500 yr BP、6700~1100 yr BP)。9500~6700 yr BP期间,本区域基本都沉积了风成砂,湖泊岸堤的14C测年均未发现早全新世高湖面的证据。通过地球物理化学指标分析及可靠14C测年,重建了区域末次冰消期以来的气候干湿变化历史:15800~13000 yr BP,为冷干的气候环境;13000~9500 yrBP,为凉湿的气候环境;9500~6700 yr BP,为暖干的气候环境;6700~4300 yr BP,为暖湿的气候环境,其中6700~5650 yr BP为气候最适宜期;4300~2700 yr BP,为干旱/湿润的过渡时期;2700~0 yr BP,为干旱的气候环境。     

Distribution of isotopes and chemicals in precipitation in Shule River Basin,northwestern China:an implication for water cycle and groundwater recharge

The distribution of stable isotopes and ions in precipitation in the Shule River Basin,northwestern China,were investigated to understand the regional water cycle and precipitation input to groundwater recharge.The study found that the mean annual concentrations of Ca2+,Na+,SO42–,Cl–,Mg2+,NO3–,and K+ in the basin were lower than those in other arid areas of northwestern China.The average concentrations of ions in the lower reaches of the Shule River were higher than those in the upper reaches.The results showed that the main ionic concentrations decreased with the increase of precipitation amount,indicating that heavy precipitation cannot only wash crustal aerosols out of the atmosphere,but also create a dilution effect.Cl– and Na+ in precipitation had a strong and positive correlation,suggesting a common origin for the two ions.However,the excess of Na+,combined with non-marine SO42– and NO3–,indicated that some ions were contributed by terrestrial origins.In the extremely arid regions of northwestern China,the evaporation process obviously changes the original relationship between δ2H and δ18O in precipitation,and leads to dexcess values 8‰.δ18O and temperature were significantly correlated,suggested that temperature strongly affected the characteristics of isotopes in the study area.The δ18O value indicates a dominant effect of westerly air masses and southwest monsoon in warm months,and the integrated influence of westerly and Siberian-Mongolian polar air masses in cold months.The d-excess values were generally lower in warm months than those in cold months,indicating that post-condensation processes played a significant role in the water cycle.The results provide reliable precipitation input information that can be used in future groundwater recharge calculations in the study area.     

1957—2015年叶尔羌河流域气候变化特征及其径流响应

根据流域内气象、水文站点的长期观测数据,利用线性趋势、相关系数、累积距平、Mann-kendall(M-K)突变检验等方法分析不同区域的干、湿季气候变化特征,并假定不同的气候情景组合,分析径流对气候变化的响应程度。结果表明:(1)1957-2015年4个单元气温和降水量呈增加趋势;除上游外,相对湿度、平均风速和大风日数呈减小趋势,流域径流量呈增加趋势。(2)气温在1996年发生突变;降水量未出现明显突变点;相对湿度在2005年左右发生突变;除下游外,平均风速在1983年发生突变;径流量于1993年发生突变,突变后径流量增加了9.08×10^8m^3。(3)相关性分析显示,流域径流量与湿季平均气温、平均最低(最高)气温呈极显著正相关,与湿季平均风速、大风日数和相对湿度呈负相关,除上游径流与干季降水量呈正相关外,其他区域与降水量呈负相关。(4)敏感性分析表明,当降水量不变,气温升高1℃,径流量增加9.06%;当气温不变,降水量增加10%,径流量减小1.67%,这主要与径流组成有关。流域77.4%的径流量来自雪冰融水补给,当降水量增加时,气温降低,减少了冰川积雪的融化,因而流域径流与气温呈正相关,与降水量呈负相关,且对气温变化更敏感。     

Cocoa production in Ecuador in relation to dry-season escape from pod rot caused by Crinipellis perniciosa and Moniliophthora roreri

Cropping and disease patterns were observed over a period of 4 years in individual cocoa trees at three contrasting sites near Quevedo, Ecuador, with the aim of evaluating the importance of dry season production and the consequent avoidance of pod disease caused by Crinipellis perniciosa and Moniliophthora roreri. Distinction of the diseases on necrotic pods was aided by splitting open pods after removal from the tree. The year was divided into wet season (April to September) and dry season (October to March) harvest periods. The 3-month lag between the actual wet and dry seasons and these harvest periods allowed time for symptom development. Combined disease losses ranged from 19·0% to 62·1 % at the various sites. At all sites and in each year, more ripe healthy pods were harvested in the dry season harvest period than in the wet season harvest period. In general, pod losses caused by C, perniciosa were curtailed more sharply by the dry season than those caused by M. roreri , which at one site caused as much damage in the dry season as in the wet season. The proportion of the annual production falling in the dry season harvest period varied among sites and between years at a given site. A comparison of trees from two progenies growing side by side showed consistent differences in cropping patterns, and identified certain trees that were productive, yielded consistently in the dry season harvest period, and were little affected by M, roreri. Analysis of long-term rainfall data for the Quevedo region indicated that years which lack a normal dry season do occur, but only once every 10 years on average. Further exploitation of disease escape through selection and breeding appears to be both feasible and appropriate.