扎龙湿地藻类植物群落结构特征及水质初步评价

扎龙湿地是我国北方同纬度地区保留最完整、最原始、最开阔的湿地生态系统,地处中温带,属大陆性季风气候。为了探究其藻类植物群落的变化特征及其与水环境的关系,本文于2011年春、夏、秋季对扎龙湿地的藻类植物群落进行调查分析,共发现藻类植物349个分类单位(包括变种、变型),隶属于8门105属,藻类植物群落全年均以绿藻为主导,其组成呈绿藻-硅藻型。优势种中绿藻门主要以镰形纤维藻(Ankistrodesmus falcatus)和四尾栅藻(Scenedesmus quadricauda)为主,硅藻门以弯棒杆藻(Rhopalodia gibba)和隐头舟形藻(Navicula cryptocephala)为主,优势种组成具有明显的季节演替现象。藻类植物细胞密度呈现明显的单峰型,夏季最高,平均为10.74×10~4ind./L。湿地研究区域分为开阔型水域、小型封闭水域、湿地型水域和湖泊型水域四个生态类型,不同水域藻类植物群落结构特征明显不同。经聚类和多维尺度分析,将不同采样点的藻类植物群落分为四组,多样性指数表明湿地水体处于轻度污染或无污染状态。综合研究结果可以认为扎龙湿地的水体基本处于贫营养-中营养状态,只有极少数水域处于富营养状态。     

基于稳定同位素的东太平洋大青鲨(Prionace glauca)营养级研究

碳、氮稳定同位素为分析淡水和海洋生态系统的生物营养关系提供了有力手段,但在大洋鱼类中的应用还很少。本研究以热带东太平洋大青鲨(Prionace glauca)整节脊椎骨作为样品(叉长范围153—242cm),运用稳定同位素技术,分析大青鲨的δ~(13)C值和δ~(15)N值及其变化,比较不同基线生物的选择对营养级计算的影响。结果表明,大青鲨δ~(13)C范围为–15.76‰—–13.41‰,最大差值2.35‰;δ~(15)N范围为10.62‰—17.72‰,最大差值7.1‰;δ~(13)C值和δ~(15)N值随个体长度的变化不明显(可能原因是样品鱼均为较大个体),性别间的差异不显著,但不同基线生物的选择对营养级计算值的影响较大。本文研究表明,通过整节脊椎骨的稳定同位素测定来获得大青鲨的摄食特征信息是可行的。由于基线生物对营养级计算的影响问题难以在短期内解决,今后可将相对营养级或营养级的变化作为重点,研究人类活动(如捕捞)对大洋鱼类摄食和营养级的影响。     

北大西洋大青鲨渔业生物学初步研究

大青鲨(Prionace glauca)是金枪鱼延绳钓渔业中最主要的兼捕鱼种之一,作为海洋生物链的顶端物种对海洋生态系统的稳定性和多样性起到了重要作用。作者根据中国金枪鱼渔业科学观察员在北大西洋海域(3°~55°N,15°~40°W)采集的2 112尾大青鲨数据,按不同性别对其渔业生物学特征进行初步研究。结果表明:雌、雄大青鲨的优势叉长组分别为180~220 cm、190~230 cm,雄性叉长均值显著大于雌性,雌、雄性比符合1︰1;大青鲨叉长-全长、尾凹长-全长的线性关系分别为L_F=0.8008L_T+7.3361,L_P=0.7576L_T–1.8479;北大西洋热带海域(3°~13°N)兼捕的大青鲨群体组成以大个体为主(180~240 cm),冰岛附近海域(48°~51°N)兼捕的大青鲨群体组成以小个体为主(100~210 cm);大青鲨叉长和质量关系式为W_R=7×10~(–6)L_F~(2.9994);大青鲨肝脏为性腺的发育提供能量,成熟个体的肝质量指数显著小于未成熟个体;热带海域兼捕的大青鲨以性成熟个体为主(96.9%),冰岛海域兼捕的大青鲨以未成熟个体居多(77.1%);50%雌性性成熟个体对应的叉长为178.7 cm,50%雄性性成熟个体对应叉长为173.6 cm;雌性怀仔大青鲨的叉长与其怀仔数量线性关系为L_S=0.419×L_F–49.7(R~2=0.3905),幼仔雌雄性比符合1︰1;胃含物中以沙丁鱼和鱿鱼出现频率最高。作者的研究有助于更好地了解北大西洋大青鲨的生物学特征,为区域性渔业管理组织评估大青鲨种群资源状态提供数据参考。     

便携式高频地波雷达海流探测长周期工作性能试验

2013年1月29日至3月15日在台湾海峡西南部海域进行了OSMAR-S100便携式高频地波雷达与浮标观测海流数据的长周期对比试验,验证了雷达系统在探测海流方面的准确性、可靠性和稳定性.通过实测海流与雷达矢量流的复相关分析,选定3 m层的海流为对比代表层.试验期间实测流速为0.0~120.0 cm/s,雷达海流有效探测区内的矢量流流速、流向的观测误差较小,能够满足实时监测海洋表层流的需要,高精度区流速、流向的均方根误差分别为9.1 cm/s和24.8°,边缘区的均方根误差为13.3~24.8 cm/s和39.4°~39.6°,与国内外达到业务化运行要求的同类产品实际观测精度相当.     

A Preliminary Study on the Soft–Sediment Deformation Structures in the Late Quaternary Lacustrine Sediments at Tashkorgan, Northeastern Pamir, China

This study identified soft–sediment deformation structures(SSDS) of seismic origin from lacustrine sediments in the late Quaternary paleo–dammed lake at Tashkorgan, northeastern Pamir. The observed deformation structures include sand dykes, liquefied diapir and convolute structures, gravity induced SSDS, and thixotropic pillar and tabular structures. We conducted a preliminary study on the morphology, formation and trigger mechanisms of pillar and tabular structures formed by liquefaction of underlying coarse sand and thixotropy of the upper silty clay. The regional tectonic setting and distribution of lacustrine strata indicate that the most probable trigger for the SSDS in lacustrine sediments was seismic activity, with an approximate earthquake magnitude of M6.0; the potential seismogenic fault is the southern part of the Kongur normal fault extensional system. AMS 14 C dating results indicate that the SSDS were formed by seismic events occurring between 26050±100 yr BP and 22710±80 yr BP, implying intense fault activity in this region during the late Pleistocene. This study provides new evidence for understanding tectonic activity and regional geodynamics in western China.     

内蒙古新地沟金矿床黄铁矿热电性特征及深部找矿意义

内蒙古新地沟金矿是中型绿岩型金矿床,但已属于严重资源危机的矿山,急待寻找接替资源,因此对新地沟金矿床进行深部远景预测具有十分重要的意义。本文根据找矿矿物学和成因矿物学理论,利用显微镜、电子探针及热电仪系统分析新地沟金矿床不同标高和矿段中黄铁矿的热电型标型特征,研究结果表明:新地沟金矿床中黄铁矿的晶型以立方体、五角十二面体及聚形为主;热电系数变化主要集中在-331.10~340.20μV·°C~(-1)范围内,导电型多以N型为主,约占总含量的80%;成矿温度主要集中于250~340℃,属于中温矿床。黄铁矿热电性参数XNP变化范围较大,估算矿体剥蚀率为67.96%~74.31%。通过对黄铁矿导型的空间分布规律和矿体剥蚀分析表明:油篓沟矿段位于矿体中底部,向深部可能有小规模延伸,小西沟矿段钻孔ZK106在深部有较大规模的延伸,其矿化前景最好;小西沟矿段钻孔ZK102深部矿化前景次之;大汗青矿段钻孔ZK_2802其深部矿化前景较差。综合分析认为,该矿床深部具有较好的找矿潜力。     

辽宁凌源四合当地区九佛堂组珍稀化石层划分及意义

辽宁省凌源市四合当地区九佛堂组含有丰富的中生代热河生物群化石,尤其是珍稀化石.通过剖面测制、化石采集以及实地调查等手段,将九佛堂组划分为3个段,确定了化石层的分布及重要化石的产出层位,同时命名了3个化石层：一段的韩家沟层、二段的卅二道湾层、三段的四合当层,加深了辽西九佛堂组化石层的研究程度.     

基于面向对象分类的稀土开采区遥感信息提取方法研究

离子吸附型稀土矿是我国宝贵的矿产资源,运用遥感影像分类技术提取稀土开采区可以准确地实现对稀土开采状况的监测,但仅利用光谱信息往往难以保证分类精度。本文以江西寻乌稀土矿区为研究区,以IKONOS影像为数据源,应用面向对象分类方法提取了稀土开采区的遥感信息。针对稀土开采区的分布特点,选择基于边缘的分割算法进行影像分割;结合地形信息、光谱信息及几何信息建立规则集,进行特征提取;最后采用隶属度函数法实现面向对象分类,并与传统的光谱角填图分类进行对比分析。研究结果表明,面向对象分类法提取稀土开采区的总体精度为92.49%,Kappa系数为0.857 6,与传统监督分类方法相比有了很大的提高。     

Mid-Cretaceous Hothouse Climate and the Expansion of Early Angiosperms

The remarkable transition of early angiosperms from a small to a dominant group characterized the terrestrial ecosystem of the Cretaceous. This transition was instigated and promoted by environmental changes. Mid-Cretaceous is characterized by major geological events that affected the global environment. δ18O, palaeothermometer TEX86, and other climatic indices from marine sediments suggest rapid temperature increase during mid-Cretaceous despite occasional short cooling events. Simultaneously, terrestrial deposits in East Asia changed from coal-bearing to shale, then to red beds and evaporites. Plant assemblages and other paleoclimate indicators point to rapid aridification for mid-Cretaceous terrestrial environments. In addition, the wildfires were frequently spread all over the earth by the numerous charcoal evidence during the Mid-Cretaceous. Thus, we speculate that the seasonally dry and hot conditions of mid-Cretaceous created a fiery hothouse world. Early angiosperms increased in abundance and diversity and evolved from a few aquatic species to terrestrial herbaceous and then to the diversified flora of today. Angiosperms showed rapid physiological evolution in vein density and leaf area that improved photosynthesis and water absorption. These ecophysiological changes made early angiosperms well adapted to the hot and dry environment in mid-Cretaceous. Moreover, these physiological changes facilitated the fire–angiosperm cycles in mid-Cretaceous that likely further stimulated the early angiosperm evolution.     

Verification and Assessment of Real-time Forecasts of Two Extreme Heavy Rain Events in Zhengzhou by Operational NWP Models

In the present study, the performances of the NWP models on two heavy rainfalls on 20 July and 22 August 2021 over Henan Province were investigated. The impacts of the water vapor transport to the extreme rainfall were further discussed. The results showed that the regional model system in the Guangzhou Meteorological Service generally showed high scores on the extreme rainfall over Henan. The maximum 24h accumulative rainfall by the 24h forecasts by the CMA-GD reached 556 mm over Henan Province. The 24-h and 48-h Threat Score (TS) of heavy rainfall reached 0.56 and 0.64. The comparisons of the Fraction Skill Score (FSS) verifications of the heavy rainfall by CMA-GD and CMA-TRAMS at the radium of 40km reached 0.96 and 0.87. The water vapor transport to the extreme rainfall showed that the vertically integrated water vapor transport (IVT) of the whole layer before the occurrence of the heavy rainfall exhibited a double-eyes distribution in case 7 · 20. The north eye over Henan reached the same magnitude of IVT as the typhoon eye (Cempaka) over south China. The IVT over the lower troposphere (<500 hPa) showed an overwhelming magnitude than the upper level, especially in the planetary boundary layer (<700 hPa). More practical technical needs to be developed to improve its performances on the forecasting of extreme rainfall, as well as more experiments need to be conducted to examine the effects of the specific terrain and physical schemes on the extreme rainfall.