南京市城市居民对乡村旅游发展的感知及旅游行为研究

运用问卷调查法和基于SPSS软件的统计分析法,以南京市为例,从城市居民感知视角考察乡村旅游的发展情况。从旅游偏好、旅游频率和空间分布等方面探讨城市居民的乡村旅游行为特征,并进一步分析了乡村旅游的知晓度、居民对各乡村旅游点开发水平的感知与其空间分布之间的相关关系,以及居民对乡村旅游发展总体印象与旅游频率之间的相关关系。在此基础上,提出南京市乡村旅游发展的有关对策与建议。     

两次强冰雹超级单体风暴双偏振特征对比

利用S波段双偏振天气雷达资料、探空和地面常规气象观测资料及灾情调查, 对2020年6月25日河北省蠡县和2021年7月9日山东省章丘的两次特大冰雹超级单体风暴双偏振特征进行对比。结果表明:两次超级单体风暴均发生在西北气流形势下, 章丘风暴具有较强的对流有效位能、较大的湿度和较高的湿球0℃层高度。蠡县风暴强度明显大于章丘风暴, 但差分反射率柱和比差分相移柱高度明显低于章丘风暴。蠡县风暴弱回波区上方存在深厚的强度超过65 dBZ强回波悬垂, 即悬垂的冰粒子循环增长产生较大的冰雹粒子, 大的冰雹粒子进入下降通道后, 再次产生明显增长且更加不规则, 导致更强的水平极化反射率因子和更小的相关系数。湿度的垂直分布是风暴发展强度的关键环境因素之一。蠡县超级单体风暴的产生环境非常干, 章丘超级单体风暴的产生环境相对较湿。     

Spatiotemporal characteristics of precipitation and extreme events on the Loess Plateau of China between 1957 and 2009

Spatiotemporal trends in precipitation may influence vegetation restoration, and extreme precipitation events profoundly affect soil erosion processes on the Loess Plateau. Daily data collected at 89 meteorological stations in the area between 1957 and 2009 were used to analyze the spatiotemporal trends of precipitation on the Loess Plateau and the return periods of different types of precipitation events classified in the study. Nonparametric methods were employed for temporal analysis, and the Kriging interpolation method was employed for spatial analysis. The results indicate a small decrease in precipitation over the Loess Plateau in last 53 years (although a Mann–Kendall test did not show this decrease to be significant), a southward shift in precipitation isohyets, a slightly delayed rainy season, and prolonged return periods, especially for rainstorm and heavy rainstorm events. Regional responses to global climate change have varied greatly. A slightly increasing trend in precipitation in annual and sub‐annual series, with no obvious shift of isohyets, and an evident decreasing trend in extreme precipitation events were detected in the northwest. In the southeast, correspondingly, a more seriously decreasing trend occurred, with clear shifts of isohyets and a slightly decreasing trend in extreme precipitation events. The result suggests that a negative trend in annual precipitation may have led to decreased soil erosion but an increase in sediment yield during several extreme events. These changes in the precipitation over the Loess Plateau should be noted, and countermeasures should be taken to reduce their adverse impacts on the sustainable development of the region. Copyright © 2013 John Wiley & Sons, Ltd.     

现代沉积的210Pb计年

²¹⁰Pb具有百年时间尺度沉积计年的重要价值。²¹⁰Pb_ex计年假设：沉积物是封闭系统；进入水体的²¹⁰Pb能有效地转移到沉积物中并不发生沉积后迁移；非过剩²¹⁰Pb与其母体²²⁶Ra保持平衡。²¹⁰Pb_ex计年可用稳定输入通量-稳定沉积物堆积速率模式、常量初始浓度模式或恒定补给速率模式。沉积物柱芯必须保持原态并以0．5～1cm间隔分截；用相应层节²²⁶Ra校正。沉积物表层混合作用及²²²Rn的丢失可能导致顶部²¹⁰Pb_ex异常。季节性缺氧湖泊沉积物顶部可能存在²¹⁰Pb及²¹⁰Po的再迁移。²¹⁰Pb与¹³⁷Cs两种计年方法原理上具有根本差别。²¹⁰Pb，¹³⁷Cs与沉积纹理方法对比是准确计年的重要保证。     

Effects of rainfall on soil moisture and water movement in a subalpine dark coniferous forest in southwestern China

Water content and movement in soil profile and hydrogen isotope composition (δD) of soil water, rainwater, and groundwater were examined in a subalpine dark coniferous forest in the Wolong National Nature Reserve in Sichuan, China, following rainfall events in 2003–2004. Light rainfall increased water content in the litter and at soil depth of 0–80 cm, but the increased soil water was lost in several days. Heavy rainfall increased soil water content up to 85% at depths of 0–40 cm. Following the light rainfall in early spring, the δD of water from the litter, humus, illuvial, and material layers decreased first and then gradually reached the pre‐rainfall level. In summer, light rainfall reached the litter humus, and illuvial layer, but did not hit the material layer. Heavy rainfall affected δD of water in all layers. The δD of soil interflow slightly fluctuated with rainfall events. The δD of shallow groundwater did not differ significantly among all rainfall events. Light rainfall altered the shape of δD profile curve of water in the upper layer of soil, whereas heavy rainfall greatly affected the shape of δD profile curve of water in all soil layers. Following the heavy rainfall, preferential flow initially occurred through macropores, decayed plant roots, and rocks at different depths of soil profile. With continuing rainfall, the litter and surface soil were nearly saturated or fully saturated, and infiltration became homogeneous and plug‐like. Forest soil water, particularly in deeper soil profile, was slightly affected by rainfall and, thus, can be a source of water supply for regional needs, particularly during dry seasons. Copyright © 2011 John Wiley & Sons, Ltd.     

美国Landers地震和Hector Mine地震前震源机制与主震机制一致现象的研究

100多年来,地震学家一直在寻求预测地震的方法,然而目前还没有一种可靠的方法用于实际(Geller 1997).由于地震预测在防震减灾方面的重要性,很多科学家致力于各种方法的尝试.如crampin等(2002 在冰岛坚持利用S波分裂进行长期的地震预测研究,Gao et al.     

Microbialite of anoxic condition from Permian-Triassic transition in Guizhou,China

Spherical microfossils are present in the Hindeodus parvus zone of the Lower Triassic in Ziyun,Guizhou Province. They generally range from 0.15 to 0.30 mm across,with micritic wall and filled by micro-sparry calcites,and are evenly scattered in micritic matrix. Their abundance makes the rock as-signed to microbialites. The accompanied organisms include ostracods and algal mat,but no gastro-pods or bivalves. Presence of small (<7 μm) pyrite framboids indicates that this bed formed in anoxic conditions. In some sections,this bed is overlain and underlain by tidal-flat micritic limestone with microgastropods and small burrows. Occurrence only in deposits on reef top indicates that the micro-bial organism was benthic,and needed sunlight in life. The size of the microbial fossil exceeds that of any bacteria or cyanobacteria. Thus,it does not belong to these two phyla. It may belong to lower green algae,and is assigned to a new species in a new genus,Ziyunosphaeridium sinensis gen. et sp. nov. Up to now,the rocks described as microbialites from the Permian-Triassic transition include six types: (1) porous micritic limestone such as that descried from Japan by Sano and Nakashima (1997),(2) limestone with rich globular microfossils such as that described from the Nanpanjiang Basin in China by Lehrmann (1999),(3) dendroidal limestone such as that described from the vicinity of Chongqing by Kershaw et al. (1999),(4) spherical microbial limestone adapted to anoxic environments described from Ziyun,Guizhou reported in this paper,(5) limestone with cyanobacterial fossils such as that described by Wang et al. (2005),and (6) stromatolites. All these microbialites are not reefs in the proper sense,and the argument that Permian reef ecosystems extended into the Mesozoic is incorrect.     

Modeling of gas generation from the Alam El-Bueib formation in the Shoushan Basin, northern Western Desert of Egypt

The Shoushan Basin is an important hydrocarbon province in the northern Western Desert, Egypt, but the burial/thermal histories for most of the source rocks in the basin have not been assigned yet. In this study, subsurface samples from selected wells were collected to characterize the source rocks of Alam El-Bueib Formation and to study thermal history in the Shoushan Basin. The Lower Cretaceous Alam El-Bueib Formation is widespread in the Shoushan Basin, which is composed mainly of shales and sandstones with minor carbonate rocks deposited in a marine environment. The gas generative potential of the Lower Cretaceous Alam El-Bueib Formation in the Shoushan Basin was evaluated by Rock–Eval pyrolysis. Most samples contain sufficient type III organic matter to be considered gas prone. Vitrinite reflectance was measured at eight stratigraphic levels (Jurassic–Cretaceous). Vitrinite reflectance profiles show a general increase of vitrinite reflectance with depth. Vitrinite reflectance values of Alam El-Bueib Formation range between 0.70 and 0.87 VRr %, indicating a thermal maturity level sufficient for hydrocarbon generation. Thermal maturity and burial histories models predict that the Alam El-Bueib source rock entered the mid-mature stage for hydrocarbon generation in the Tertiary. These models indicate that the onset of gas generation from the Alam El-Bueib source rock began in the Paleocene (60 Ma), and the maximum volume of gas generation occurred during the Pliocene (3–2 Ma).     

SSA1—1型声学水位在长江口潮位站的应用

本文介绍了长江口区水文泥沙概况，举例说明了ＳＳＡ１－１型声水位计在崇头潮位站比测试验和投产应用情况，结果表明该水位计是收集长江口区潮位资料较理想的仪器。