1997—2017年塔克拉玛干沙漠腹地降水特征

利用塔克拉玛干沙漠腹地塔中气象站1997—2017年逐日和逐时降水资料,分析塔克拉玛干沙漠腹地降水日变化特征、极端强降水特征及其天气背景。结果表明：1997—2017年研究区降水量呈增加趋势、降水日数呈减少趋势,大雨雨量和雨日明显增加,降水呈增强演变。降水多见于6月,最大雨强为8.4 mm·h^-1。降水量日变化呈多峰特征,降水量最大值出现在23：00,06：00是降水频次最多时刻。降水强度和降水频次对降水量作用不同,午后至前半夜强度大,频次少;而后半夜至清晨频次多,强度小。降水以短历时降水为主,其中1～3 h的短历时降水对总降水量贡献率高达61.76%。日降水和小时降水的99百分位强度阈值分别为15.3 mm·d^-1和6.0 mm·h^-1,大于90百分位极端降水量占总降水量贡献率近半。极端强降水天气发生在南疆盆地受北纬40°以南低槽、切变槽或弱的气旋式风场控制地区,南疆盆地提前增湿,民丰850 hPa比湿接近或超过10 g·kg^-1的背景下,降水连续性较差,多中小尺度引发局地短时降水。     

徐闻南山镇红树林沉积物及红树植物中重金属的累积特征与迁移规律

为探究重金属在红树林沉积物及红树植物中的分布累积及迁移规律,选取了徐闻南山镇红树林为研究对象,通过测定红树林沉积物及红树植物不同部位（根、茎、叶）的重金属质量分数,运用富集因子、生物富集系数、转移系数及相关性分析等方法进行分析。结果表明：1）红树林沉积物重金属质量分数表现为铬（Cr）＞锌（Zn）＞镍（Ni）＞铜（Cu）＞铅（Pb）＞砷（As）＞汞（Hg）＞镉（Cd）,为中等变异程度;除了镍（Ni）元素外,其余7种重金属未超过国家一级标准,除了铅（Pb）元素外,其余7种重金属均超过广东省土壤环境背景值,说明研究区沉积物中重金属具有一定的积累效应。2）沉积物中砷（As）、铜（Cu）、锌（Zn）、汞（Hg）、镍（Ni）、铬（Cr）富集因子值均＞1.5,说明受到轻微人为活动影响;各站位镍（Ni）富集因子值均＞5,结合研究区背景,反映了镍（Ni）受到自然和人为输入的共同影响。3）白骨壤体内重金属主要集中在根部,而红海榄体内重金属在根茎叶中分布相对均匀。白骨壤根茎叶部位的大多数重金属质量分数远高于红海榄,说明白骨壤对重金属的吸附能力比红海榄强。汞（Hg）集中分布在植物的叶片部位,且与其他重金属之间相关性不明显;推测汞（Hg）主要通过叶片吸收进入植物体内,与交通运输污染有关。4）不同红树植物对不同重金属富集能力各异,白骨壤对重金属的富集能力表现为：镉（Cd）＞砷（As）＞铜（Cu）＞锌（Zn）＞汞（Hg）＞铅（Pb）＞镍（Ni）＞铬（Cr）,红海榄表现为：镉（Cd）＞铜（Cu）＞汞（Hg）＞锌（Zn）＞铅（Pb）＞砷（As）＞镍（Ni）＞铬（Cr）。白骨壤和红海榄对汞（Hg）的运移能力都较强;红海榄对镉（Cd）的富集能力和转运能力都较强,而白骨壤对镉（Cd）富集能力较强,转运能力却较弱,这说明红树植物对重金属元素的富集能力与转运能力不存在正比关系。     

福建省复杂地形下旬平均气温分布式模拟

为建立高时空分辨率的福建省复杂地形下气温栅格数据集,利用福建省及其周边33个常规气象站观测资料,基于数字高程模型（DEM）数据,综合考虑海拔、太阳总辐射、地表长波有效辐射对旬平均气温的影响,模拟了福建省复杂地形下旬均温的空间分布。结果表明：1）常规站验证结果显示：各旬气温绝对误差平均值（MAE）最小为0.46℃,最大为2.3℃,全年平均为0.87℃;加密站验证结果显示,MAE最大为2.3℃,最小0.5℃,全年平均为0.96℃。2）模拟结果能反映旬均温的宏观分布规律与局地细节特征。宏观范围内,旬均温受纬度影响较大,由北至南气温逐渐升高,沿海地区旬均温整体高于内陆,山区旬均温明显较低;局地范围内,各坡向上气温差异显著,海拔越高、坡度越大,差异越明显;地形因子对旬平均温的影响具有季节差异,具体表现为冬季时地形因子对旬均温的影响最大,秋季次之,春夏季节中地形因子对旬均温的影响最弱。     

X-ray activity from different types of stars

X-ray emission is an important indicator of stellar activity. In this paper, we study stellar Xray activity using the XMM-Newton and LAMOST data for different types of stars. We provide a sample including 1259 X-ray-emitting stars, of which 1090 have accurate stellar parameter estimations. Our sample size is much larger than those used in previous works. We find a bimodal distribution of the X-ray to optical flux ratio(log(fX/fV)) for G and K stars. We interpret that this bimodality is due to two subpopulations with different coronal heating rates. Furthermore, using the full widths at half maxima calculated from Hα and Hβ lines, we show that these stars in the inactive peaks have smaller rotational velocities. This is consistent with the magnetic dynamo theory that presumes stars with low rotational velocities have low levels of stellar activity. We also examine the correlation between log(fX/fV) and luminosity of the excess emission in the Hα line, and find a tight relation between the coronal and chromospheric activity indicators.     

连作马铃薯根系分泌物鉴定及其对尖孢镰孢菌(Fusarium oxysporum)的作用

为了揭示马铃薯连作化感物质与枯萎病之间的关系,通过水培和田间长期定位试验相结合方法,收集不同连作年限马铃薯根系分泌物,采用GC-TOF-MS进行分离鉴定.结果表明:在检测到的马铃薯根系分泌的48种物质中有机酸占30种.比较轮作、连作5年和连作10年马铃薯根系分泌物中有机酸的相对含量,发现苹果酸和棕榈酸的差异比较大.马铃...     

Decomposition analysis on direct material input and dematerialization of mining cities in Northeast China

Material dematerialization is a basic approach to reduce the pressure on the resources and environment and to realize the sustainable development. The material flow analysis and decomposition method are used to calculate the direct material input (DMI) of 14 typical mining cities in Northeast China in 1995-2004 and to analyze the demateri-alization and its driving factors in the different types of mining cities oriented by coal, petroleum, metallurgy and multi-resources. The results are as follows: 1) from 1995 to 2006, the increase rates of the DMI and the material input intensity of mining cities declined following the order of multi-resources, metallurgy, coal, and petroleum cities, and the material utilizing efficiency did following the order of petroleum, coal, metallurgy, and multi-resources cities; 2) during the research period, all the kinds of mining cities were in the situation of weak sustainable development in most years; 3) the pressure on resources and environment in the multi-resources cities was the most serious; 4) the petro-leum cities showed the strong trend of sustainable development; and 5) in recent years, the driving function of eco-nomic development for material consuming has continuously strengthened and the controlling function of material utilizing efficiency for it has weakened. The key approaches to promote the development of circular economy of min-ing cities in Northeast China are put forward in the following aspects: 1) to strengthen the research and development of the technique of resources' cycling utilization, 2) to improve the utilizing efficiency of resources, and 3) to carry out the auditing system of resources utilization.     

山东乳山英格庄金矿床地质特征及成因浅析

英格庄金矿为胶东牟平-乳山成矿带上的一个中型金矿床。该矿床矿体严格受金牛山断裂带控制,呈脉状、透镜状和囊状平行斜列式产出;矿体平均厚1．58～1．98m,平均品位3．96×10^-6～4．77×10^-6。矿石类型主要为黄铁矿石英脉型;矿石中金属矿物主要为银金矿、自然金、黄铁矿等。围岩蚀变包括绢云母化、硅化、绿泥石化、黄铁矿化等。研究表明,英格庄金矿床为一中低温热液脉型金矿,属Groves等提出的造山型金矿范畴。     

Global distribution of summer chlorophyll blooms in the oligotrophic gyres

Chlorophyll blooms consistently develop in the oligotrophic NE Pacific in late summer, isolated from land masses and sources of higher chlorophyll waters. These blooms are potentially driven by nitrogen fixation, or by vertically migrating phytoplankton, and a better understanding of their ubiquity could improve our estimate of the global nitrogen fixation rate. Here, global SeaWiFS chlorophyll data from 1997 to 2007 are examined to determine if similar blooms occur in other oligotrophic gyres. Our analysis revealed blooms in five other areas. Two of these are regions where blooms have been previously identified: the SW Pacific and off the southern tip of Madagascar. Previously, unnoticed summer blooms were also identified in the NE and SW Atlantic and in a band along 10°S in the Indian Ocean. There is considerable variation in the intensity and frequency of blooms in the different regions, occurring the least frequently in the Atlantic Ocean. The blooms that develop along 10°S in the Indian Ocean are unique in that they are clearly associated with a hydrographic feature, the 10°S thermocline ridge, which explains the bloom within a conventional upwelling scenario. The environment and timing of the blooms, developing in oligotrophic waters in late summer, are conducive to both nitrogen fixers and vertically migrating phytoplankton, which require a relatively stable water column. However, the specific locations of the chlorophyll blooms generally do not coincide with areas of maximum levels of nitrogen fixation or Trichodesmium. The NE Pacific chlorophyll blooms develop in a region with a very high SiO₄/NO₃ ratio, where silicate will not be a limiting nutrient for diatoms. The blooms often develop between eddies, wrapping around the periphery of anti-cyclonic features. However, none of the areas where the blooms develop have particularly high eddy kinetic energy, from either a basin-scale or a mesoscale perspective, suggesting that other factors, such as interactions with a front or dynamics associated with the critical latitude, operate in conjunction with the eddy field to produce the observed blooms.     

Challenges in developing China's marine protected area system

Since the 1980s, there have been continuous increases in the coverage of marine protected areas (MPAs) in China, and a total of 158 MPAs have been declared. The MPA system in China is characterized by (1) decentralised designation and management with reduced control from the central government; (2) a dominance of de jure fully protected MPAs that are often implemented as de facto multiple-use areas; and (3) a lack of objective evaluation processes. To improve China's MPA system requires an appropriate integration of fully protected and multiple-use MPAs, and an approach that balances the advantages of top-down and bottom-up approaches.     

西施舌器官的发生和形成

本文叙述采用“直接法”、连续又系统地观察西族舌幼虫至幼贝器官的发生和形成的细微，变的全过程，有全套显微绘图和摄影并详细文字说明，特别是对雅贝与幼贝的晶杆囊、平衡囊和三对神经节的形成之描述，是国内，外的首例。