Spatio-temporal analysis of the melt onset dates over Arctic sea ice from 1979 to 2017

The melt onset dates(MOD) over Arctic sea ice plays an important role in the seasonal cycle of sea ice surface properties, which impacts Arctic surface solar radiation absorbed by the ice-ocean system. Monitoring interannual variations in MOD is valuable for understanding climate change. In this study, we investigated the spatio-temporal variability of MOD over Arctic sea ice and 14 Arctic sub-regions in the period of 1979 to 2017 from passive microwave satellite data. A set of mathematical and ...     

江汉盆地新沟油田新沟嘴组盐韵律多级划分及其地质意义

江汉盆地为中国东部典型的中、新生代盐湖盆地,近些年在新沟油田古近系新沟嘴组发现致密油藏,储集层主要为与盐韵律相关的白云岩和粉砂岩层。为了探究盐韵律的发育特征及其意义,作者以岩心精细观察为基础,结合测录井、分析化验资料,根据盐矿物种类、剖面结构和厚度,对新沟嘴组盐韵律发育规模进行了不同级别的划分,对各级韵律的剖面特征进行了描述,并对其形成机理进行了分析。在此基础上,从古气候及油气2个角度探讨了盐韵律的地质意义。盐韵律的形成是湖平面上升-下降不断变化的直接响应。新沟嘴组盐韵律中广泛发育广温相盐类矿物白云石、方解石,指示江汉盆地古近系新沟嘴期的气候特征为古温度介于寒冷和炎热之间的过渡型半干旱-干旱气候;一个完整的盐韵律可以形成一个生储盖组合,对油气生成、储集和保存具有重要意义。     

微生物絮凝剂投加方式对好氧颗粒污泥性能的影响

为提高好氧污泥颗粒化速度, 采用微生物絮凝剂, 探讨在好氧颗粒污泥培养过程中微生物絮凝剂的投加方式对颗粒污泥理化性能及生物降解效能的影响。结果表明:微生物絮凝剂每隔2、3、5、7 d投加一次时, 均可培养出成熟的好氧颗粒污泥, 微生物絮凝剂的投加方式对好氧污泥颗粒化的影响较显著;微生物絮凝剂最佳投加方式为每5天投加一次, 此时颗粒化速度快, 颗粒形成时间由未投加的60 d缩短为42 d, 好氧颗粒污泥疏水性好, 污泥体积指数稳定在40 mL/g左右, 沉降速度达35.06 m/h, COD、氨氮和总磷的去除率分别为96.55%、93.29%和87.29%。     

The formation of submillisecond pulsars and the possibility of detection

Pulsars have been recognized to be normal neutron stars, but sometimes have been argued to be quark stars. Submillisecond pulsars, if detected, would play an essential and important role in distinguishing quark stars from neutron stars. We focus on the formation of such submillisecond pulsars in this paper. A new approach to the formation of a submillisecond pulsar (quark star) by means of the accretion-induced collapse (AIC) of a white dwarf is investigated. Under this AIC process, we found that: (i) almost all newborn quark stars could have an initial spin period of ∼0.1 ms; (ii) nascent quark stars (even with a low mass) have a sufficiently high spin-down luminosity and satisfy the conditions for pair production and sparking process and appear as submillisecond radio pulsars; (iii) in most cases, the times of newborn quark stars in the phase with spin period <1 (or <0.5) ms are long enough for the stars to be detected.
As a comparison, an accretion spin-up process (for both neutron and quark stars) is also investigated. It is found that quark stars formed through the AIC process can have shorter periods (≤0.5 ms), whereas the periods of neutron stars formed in accretion spin-up processes must be longer than 0.5 ms. Thus, if a pulsar with a period shorter than 0.5 ms is identified in the future, it could be a quark star.     

关于气象与人体健康研究的几个问题

关于气象、环境与健康问题的研究可总结为如下几个问题:1)气候变化及其影响,2)天气、气候变化与人类健康,3)大气污染与人类健康,4)关于气象条件与疾病的机理研究,5)环境与健康危险度评价。作者认为以下几个问题值得我国学者予以关注:1)气象与健康问题的检测,2)气侯变化与人类健康,3)气象与人类健康关系的机理研究,4)应用数值模式研究气象与健康问题,5)环境与健康危险度评价,6)疾病预测和预警研究,7)多学科交叉研究和更多部门对气象与健康问题的介入。     

Soil carbon and nitrogen dynamics in southern African savannas: the effect of vegetation-induced patch-scale heterogeneities and large scale rainfall gradients

Savanna ecosystems are mixed plant communities in which trees and grasses co-exist thereby providing a heterogeneous landscape with a mosaic of tree-dominated and grass-dominated soil patches. Despite the important role that nutrient availability plays in these systems, detailed knowledge of differences in carbon and nitrogen cycling in soil patches predominantly covered by tree canopies or by grasses is still lacking. In this study, a process-based model was used to investigate the carbon and nitrogen dynamics in soil plots located in grass-dominated and tree/shrub-dominated soil patches along the Kalahari Transect (KT). The KT in southern Africa traverses a dramatic aridity gradient, across relatively homogenous soils, providing an ideal setting for global change studies. Here we show that there are distinctly different dynamics for soil moisture, decomposition and nitrogen mineralization between soil plots located under tree canopies and in open canopy areas, especially at the dryer end of the KT. Such differences diminished when approaching the wetter end of this transect. This study shows that in savanna ecosystems, water availability determines the patterns and rates of nutrient cycling at large scales, while at the local scales, vegetation patchiness plays an important role in nutrient cycling. Savannas are relatively stable ecosystems, resilient to small rainfall modifications, although irreversible changes may occur with stronger shifts in climate conditions.     

怎样使用电涌保护器

简述电涌保护器的工作原理,讨论电涌保护器的选型、级配要点以及安装应注意事项。     

雅鲁藏布江缝合带内韧性剪切带的地质特征及其意义

阐述了雅鲁藏布江缝合带内发现的巨型韧性剪切带的规模、构造分带性及其地质特征,指出了膝折构造带与低温高压变质带以及韧性剪切带的成因关系,阐明了缝合带内韧性剪切带在板块俯冲时的空间位置及其构造地质意义。     

钦州湾水交换能力数值模拟研究

基于普林斯顿海洋模式（Princeton Ocean Model,POM）,以M₂、S₂、K₁、O₁、M₄和MS₄ 6个分潮为驱动,建立了包含漫滩处理的高分辨率钦州湾水动力模式。与现场观测的数据对比表明,该模式能较好地刻画钦州湾的水动力特征。在此基础上建立了水质模型,模拟钦州湾的水交换过程。模拟结果表明:钦州湾水交换能力整体上较强,整个湾平均的水体半交换时间约为18 d,水体平均存留时间为45 d。空间分布上,钦州保税港区以南海域水交换能力最强,半交换时间小于1 d;沿着水道向北,水交换能力逐渐减弱;茅尾海中部半交换时间为26~28 d;茅尾海的东、西、北3个部分存在水交换滞缓区,半交换时间超过50 d。数值实验表明,采用漫滩技术对准确模拟钦州湾潮流速度和水交换能力非常重要,不考虑漫滩过程会低估钦州湾的潮流速度和水体交换能力。水平扩散系数对流速及交换时间都有影响,但影响有限。     

山东滨海低平原区盐渍土盐分的时空变异研究

文章运用地统计学的方法对山东滨海盐渍土年际空间变异和分布特征差异进行分析研究,结果表明:黄河三角洲表层土壤的盐渍化程度较高且在年际变化上呈积盐趋势,莱州湾南岸则呈脱盐趋势但盐渍化面积增加;山东滨海低平原区盐渍土受结构因素的影响加剧;表层土壤盐分的分布规律与地形有密切关系,盐渍化类型与盐渍化程度的分布特征基本吻合;莱州湾南岸应注意防止土壤碱化。由此提出因地制宜综合开发、减少土壤盐分输入、加强盐分淋洗、改善土体性质和防止土地碱化等建议,对滨海地区后备土地水土资源的开发利用具有指导作用。