西洞庭湖天然和人工改造湿地中克氏原螯虾(Procambarus clarkii)与日本沼虾(Macrobrachium nipponense)的食性差异

栖息地退化和外来物种入侵都是淡水生态系统中的主要威胁因素,因此,量化不同人类活动干扰强度下外来入侵生物和本土生物的食性组成差异,对于明确种间竞争强度,制定适合的管理对策至关重要.本研究应用碳、氮稳定同位素分析技术,比较了长江中下游西洞庭湖湿地受人类活动干扰程度不同的天然湿地和人工改造湿地中的入侵种克氏原螯虾(Procambarus clarkii)与本土种日本沼虾(Macrobrachium nipponense)的食性组成及差异.2017年8月8-18日在西洞庭湖区不同人类干扰强度的栖息地中采集了两种消费者和5种潜在食物来源样品,共计91个.测定碳氮稳定同位素含量后,使用贝叶斯混合模型,估算不同食物来源对消费者的贡献.研究发现:在两种栖息地中克氏原螯虾与日本沼虾食性均有重叠,且在改造湿地中重叠度更大.与克氏原螯虾相比,日本沼虾消费更多的动物性食物.与天然湿地相比,在改造湿地中由于克氏原螯虾数量更多,与本土种竞争食物资源,克氏原螯虾和日本沼虾δ¹³ C比值都显著升高,食性组成均发生了变化,植物性食物来源比重增加.由于食性改变,在改造湿地中仅日本沼虾δ¹⁵ N比值显著下降,克氏原螯虾在两种栖息地中δ¹⁵ N比值无显著变化.本研究证明,随着人类干扰强度增大,受干扰湿地中外来入侵生物对本土生物的影响增大.     

云南地区强震前中小地震活跃—平静的定量计算

以累计频度定量计算方法 ,讨论了云南地区 1970年以来 ,各个强震孕震区的地震活动非线性度ZL值的时间进程曲线 ,系统计算了Ms≥ 6 3级强震前的ZL值曲线 ,结果表明 :强震前地震活动非线性度ZL值异常表现出的地震孕震区的地震平静—活跃或活跃—平静过程至少出现一次 ,且震例中的 83 %开始出现平静(活跃 )的时间为强震前 1～ 2 12 年 ,强震前半年左右结束出现活跃 (平静 )。     

Fate and transport of ethanol-blended dissolved BTEX hydrocarbons: a quantitative tracing study of a sand tank experiment

To estimate the behavior of ethanol-blended dissolved BTEX hydrocarbons in groundwater, a quantitative tracing study instead of qualitative analysis was carried out by using a large sand tank, into which 2-L solution including bromide, ethanol and dissolved BTEX was injected under a controlled hydraulic condition. Mean residence time (MRT), pore volume swept by solute (V _p), retardation coefficient (R) and biodegradation rate constant (k) of injected solutes were estimated. Compared with bromide that was used as a conservative tracer, ethanol and BTEX had shorter MRT and smaller V _p with the sequence of EtOH < T < E < m/p-X < o-X < B < Br. Biodegradation was confirmed as evidenced by the consumptions of dissolved oxygen (DO), nitrate and sulfate, and the production of acetate. The sequence of k as EtOH > T > E > m/p-X > o-X > B was just opposite to the sequences of MRT and V _p. The relationship among above sequences implies that MRT and V _p can be used as indicators to assess in situ biodegradability of a solute. Biodegradation of a reactive solute can make its MRT shortened and V _p shrunk. In addition, the sorption of ethanol could be neglected (R = 1.0), whereas BTEX compounds were adsorbed (R = 1.04–1.15). It should be noted that biodegradation of a solute can affect the estimation of its retardation coefficient. To our knowledge, this paper provides an available route to quantitatively estimate biodegradability of a solute in groundwater.     

青藏高原北部新生代火山岩岩石化学特征及其构造意义

青藏高原北部东西向展布的以安山岩为主的新生代火山岩带,以黑石湖—亚克错—多格错仁一线为界可分为北侧的钙碱性岩系亚带和南侧的碱性岩带亚带。火山岩明显富钾。其形成与塔里木—柴达木板块向高原的楔入作用有关,是消减带上物质重熔上升的结果。     

地质调查助力碳达峰碳中和目标实现的路径浅析

2030年前实现碳达峰,2060年前实现碳中和是2020年我国提出的国家重大战略目标.以当前我国的二氧化碳排放及能源结构现状,要实现这一伟大目标形势十分严峻.介绍了全球碳循环过程,阐述了碳源与碳汇对于大气CO2浓度的贡献,从减源与增汇2个方面,初步分析了地质调查在推动碳达峰与碳中和目标实现中的作用与可能的贡献,并提出了...     

我国天然铀氧化物的结构和化学特征

目前我国发现的天然铀氧化物为UO_(2.03)-UO_(2.85)的连续演化系列,均属UO_2(UO_(1.75)-UO_(2.30))的萤石型立方结构,即铀氧化物氧铀比的变化未产生相应的结构相的变化,但其物理特性却随着化学成分的变化(特别是矿物中氧铀比值)而变化,导致化学成分与结构相之间的矛盾。笔者认为天然铀氧化物中的六价铀(U~(6+))并不加入矿物晶格,而是以无定形铀酰离子团(UO_2)~(2+)或以三氧化铀的水化物(UO_3·nH_2O)形式存在于UO_2晶格的缺陷中。天然铀氧化物中这些非晶质的(UO_2)~(2+)或(UO_3·nH_2O)的混入量与生成的地质环境,特别是沉淀时体系的氧逸度、硫逸度有重要关系,它不只决定了形成铀氧化物的性质,同时也决定了矿物中氧铀比的变化。沥青铀矿是UO_2结晶体与呈凝胶的(UO_2)~(2+)基团及(UO_3·nH_2O)的混合物,因此,矿物中氧铀比的变化并不引起矿物相的转换。     

Trace-element variations in an annually layered stalagmite as recorders of climatic changes and anthropogenic pollution in Central China

We analyzed variations in the Sr/Ca, Ba/Ca, REE/Ca (REE: rare earth element), Zn/Ca, and Pb/Ca ratios preserved in an annually layered stalagmite, XL21, from central China. The stalagmite record spans the 95 year period AD 1914–2008. The Sr/Ca and Ba/Ca ratios have a significant positive correlation with the stalagmite's growth rate, suggesting that they were primarily controlled by growth-rate variations. Variations in REE/Ca ratios are consistent with local temperature changes, suggesting temperature influenced REE concentrations in the stalagmite over decadal to annual timescales. Higher temperature in this humid area can increase vegetation cover, microbial activity, and organic decomposition in the soil, resulting in enhanced pCO₂, organic matter concentration and reduced pH, and consequently increased REE mobilization from the overlying soil layer and host rock. Higher temperatures may also increase the natural Zn mobilization from the overlying soil mediated by organic matter and consequently may have led to increased Zn retention in XL21. An increasing trend is seen in the Pb/Ca ratios from XL21 since 1985, which is consistent with increased lead production in this area, and indicates an increase in mine-derived lead pollution in the local environment over the past 30 years.     

水质监测浮标数据采集和接收系统设计及其应用

1)文章设计了水质监测浮标数据采集系统, 该数据采集系统包括CPU模块、控制保障模块、通讯定位模块以及接口扩展模块; 采用CF2主板为CPU模块, 辅助以单片机为核心的多功能板, 主要用于完成采集数据、保存数据、通讯等工作; 控制保障模块设计有双“看门狗”, 实现了无人值守、全天候、全过程安全工作。2)文章还设计了水质监测数据远程接收系统, 该远程接收系统主要包括数据接收模块、数据处理模块、系统预警模块和数据显示模块等四个部分, 具有操作简便、自动化程度高、图形显示直观简洁易读等特点, 实现了数据接收、存储、显示及预警等功能。     

基于广义S变换时频滤波的MT数据去噪

针对油气勘探中大地电磁(MT)数据易受各类干扰的污染,且信噪难以分离的问题,把基于广义S变换的时频滤波技术应用于MT数据处理中来,得到MT数据的S域时频分布,分析受噪MT数据在S域的时频分布特征,再在S变换时频域进行时频阈值去噪,并对滤波后的S域时频谱进行逆变换重构,分离得到去噪后的MT数据。给出了基于广义S域时频滤波的方法原理与应用步骤,对被污染的仿真和实测MT数据进行了时频阈值滤波,并与小波阈值去噪方法进行了比较研究。结果表明：基于广义S变换的时频滤波方法可有效抑制MT数据中的干扰,从噪声信号中分离出有效的大地电磁数据,且减少了人为参与,提高了MT勘测的数据质量。     

Optical properties of cirrus transition zones over China detected by CALIOP

A transition zone near cirrus lateral boundaries can be detected by CALIOP (cloud–aerosol lidar with orthogonal polarization). In the present study, for such transition zones over China, a number of optical properties, such as the backscatter coefficient and depolarization ratio, showed transitional characteristics between cirrus and clear sky. The stepped horizontal profile showed sharp changes in particle number and morphology between cirrus clouds and clear sky. The color ratio, however, was unable to show cirrus transition features because of the low signal-to-noise ratio. Typical ice particles presented a color ratio of 0.55–1.25 and a depolarization ratio of greater than 0.12, which were significantly higher than those of clear sky. Therefore, optical properties in transition took the form of stepwise horizontal profiles. The proportion of typical-featured particles also demonstrated a stepped horizontal profile similar to the optical characteristics, but the relationship between the proportion and the optical characteristics was not uniform in the cirrus clouds, transition zone, and clear sky. Therefore, the optical changes in the transition zone were caused by not only the change in particle concentration, but also the change in the particles themselves. The probability density distribution of the transition-zone widths showed a positive skewness distribution, and transition zones with widths of 3–5 km occurred most frequently. Overall, transition-zone width decreased with increasing temperature and increased with increasing vertical and horizontal wind speeds. This trend demonstrated independence with the direction of the vertical and horizontal winds. These observations implied that the transitional features were caused by material exchange, such as entrainment and turbulent transport, near the cirrus lateral boundaries, and by the phase transformation of particles, such as sublimation.