Numerical modeling the role of rubber dams on groundwater recharge and phreatic evaporation loss in riparian zones

Rubber dams have been widely built for their advantages in increase of flooding resources utilization in the north arid and semiarid plain regions of China. Rise in river water stage by the dams, particularly during the drought periods, increases lateral seepage of river water into groundwater, and thus groundwater table and phreatic evaporation loss in the riparian zones. In this study, a riparian area of the Baihe River in Nanyang of Henan Province, China was selected for investigation of influences of the river dams on the groundwater recharge and evaporation loss. A hydraulic model, HEC-RAS, was used for simulation of the river stage variations along the Baihe River, and a numerical groundwater model, MODFLOW, was applied for simulation of groundwater dynamics and estimation of river flow seepage into aquifer and evaporation loss. The results show that the dams increase river stages of 2–3 m during January 2000–December 2002. The increase in the captured groundwater recharge was 7.15–34.06 million m³/a and the increased phreatic evaporation loss occupies 10% of the increased recharge when four rubber dams were built.     

Interaction of phenanthrene with dissolved organic matter and its fractions from leachate of different landfill ages

Dissolved organic matter (DOM) in leachate from landfills of three different ages (0, 5, and 10?year) was partitioned into hydrophobic acid, hydrophobic neutral, and hydrophilic matter fractions using the fractionation method employing XAD-8 resin. The spectroscopic characteristics of these fractions were determined through constant-wavelength synchronous fluorescence spectrometry (CWSFS). The interaction characteristic of phenanthrene with these fractions was determined through the fluorescence quenching method and CWSFS. The results revealed that the composition of DOM became complex with the increase in landfill age. The partition coefficients (K _doc) for the three DOM samples of different landfill ages are in the order 10?a DOM?>?5?a DOM?>?0?a DOM. The hydrophobic fraction showed the highest K _doc value among the DOM fractions. Lower linearity Stern?CVolmer plots were observed in 10?a DOM and its hydrophobic fractions. CWSFS spectra showed that a special site was fully occupied with the addition of the quencher. Desorption was found in some fractions. Therefore, CWSFS is a sensitive tool for the detection of DOM-polycyclic aromatic hydrocarbon interaction.     

浙江白垩纪恐龙与恐龙蛋化石的时空分布

浙江省恐龙化石地质遗迹调查表明,全省有9个白垩纪陆相红层盆地产恐龙和恐龙蛋化石,至今已发现有4科5属5种恐龙骨骼和7科11属24种恐龙蛋化石。浙江省恐龙和恐龙蛋化石主要分布在天台盆地和金衢盆地的东阳、衢州、龙游、金华、浦江、兰溪一带,主要产于天台群的赖家组,衢江群的金华组、衢县组。永康、南马、新昌、嵊州、仙居、诸暨、湖山等地永康群朝川组、方岩组中也有较丰富的恐龙化石。依据恐龙和恐龙蛋化石在盆地内地层中的分布、地层的同位素年龄和相伴生的其他生物群特征等分析表明,恐龙和恐龙蛋化石的赋存地质时代以晚白垩世为主。此外,恐龙和恐龙蛋化石在浙江的广泛分布表明该地区地质历史时期气候温暖,植被茂盛,水资源丰富,是恐龙及其他生物生存繁衍的理想场所。     

Mineralogy and geochemistry of gold-bearing arsenian pyrite from the Shuiyindong Carlin-type gold deposit, Guizhou, China: implications for gold depositional processes

Arsenian pyrite in the Shuiyindong Carlin-type gold deposit in Guizhou, China, is the major host for gold with 300 to 4,000 ppm Au and 0.65 to 14.1 wt.% As. Electron miroprobe data show a negative correlation of As and S in arsenian pyrite, which is consistent with the substitution of As for S in the pyrite structure. The relatively homogeneous distribution of gold in arsenian pyrite and a positive correlation of As and Au, with Au/As ratios below the solubility limit of gold in arsenian pyrite, suggest that invisible gold is likely present as Au¹⁺ in a structurally bound Au complex in arsenian pyrite. Geochemical modeling using the laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis of fluid inclusions for the major ore forming stage shows that the dominant Au species were Au(HS)₂⁻ (77%) and AuHS_(aq)⁰ (23%). Gold-hydroxyl and Gold-chloride complexes were negligible. The ore fluid was undersaturated with respect to native Au, with a saturation index of −3.8. The predominant As species was H₃AsO₃⁰ _(aq). Pyrite in the Shuiyindong deposit shows chemical zonation with rims richer in As and Au than cores, reflecting the chemical evolution of the ore-bearing fluids. The early ore fluids had relatively high activities of As and Au, to deposit unzoned and zoned arsenian pyrite that host most gold in the deposit. The ore fluids then became depleted in Au and As and formed As-poor pyrite overgrowth rims on gold-bearing arsenian pyrite. Arsenopyrite overgrowth aggregates on arsenian pyrite indicate a late fluid with relatively high activity of As. The lack of evidence of boiling and the low iron content of fluid inclusions in quartz, suggest that iron in arsenian pyrite was most likely derived from dissolution of ferroan minerals in the host rocks, with sulfidation of the dissolved iron by H₂S-rich ore fluids being the most important mechanism of gold deposition in the Shuiyindong Carlin-type deposit.     

内蒙古乌拉特后旗乌兰敖包地区石炭系—二叠系阿木山组沉积环境

对内蒙古乌兰敖包地区野外剖面进行观测,结合剖面岩性组合、地层古生物、沉积构造、岩石学等沉积特征分析,认为剖面整体分为3段。下段为辫状河三角洲相向滨海相过渡,中段为碳酸盐台地相,上段为滨、浅海相。剖面沉积特征反映了该区石炭系—二叠系阿木山组沉积环境位于盆地边缘,经历了陆相向海相的转变,属于上超沉积。沉积相研究及边缘相的确定从沉积学角度证明额济纳旗及其邻区在石炭纪—二叠纪时期是一个裂谷盆地。研究成果可为盆地演化和沉积相研究提供依据。     

地球化学块体法在滇中层控型铜矿资源评价中的应用

以滇中地区1∶20万水系沉积物区域化探扫面资料为基础,应用地球化学块体理论与方法,对研究区内Cu地球化学块体特征及层控型铜矿资源特征进行了系统分析。共圈出5个地球化学块体、10个面积相对较小的地球化学亚块体,并根据区域成矿地质背景划分为2个Cu地球化学分区。以1km矿床勘探深度为准则,计算各(亚)块体的铜金属供应量及铜矿产资源量,预测全区潜在铜矿资源总量为586.1万t。通过追踪地球化学块体谱系,揭示了元素在地球化学块体中逐步浓集成矿的轨迹,并结合区域控矿要素,确定了11个层控型铜矿成矿远景区,其中以3-1,3-2,10-1-1-1-1-1,10-1-1-2-1-1,10-1-1-2-1-2子块体的成矿潜力较大。     

Diurnal variations of pCO2 in relation to environmental factors in the cascade reservoirs along the Wujiang River, China

We have investigated the diurnal variations of the pCO2 and related environmental factors in the cascade reservoirs with different trophic levels along Wujiang River. In surface water the pCO2 was 357±11 μatm in Hong-jiadu Reservoir, 338±48 μatm in Dongfeng Reservoir, 682±303 μatm in Wujiangdu Reservoir, and 1677±429 μatm in Liuguang, respectively. The results indicated that these cascade reservoirs had much lower pCO2 values in surface water than river did, and hypereutrophic reservoir showed larger diurnal variations of pCO2 than meso-eutrophic reservoir. In water column, pCO2 tended to increase with the depth. Phytoplankton and the environmental factors such as temperature and pH had different influences on pCO2 diurnal variations due to different trophic levels, and the effect of phytoplankton on pCO2 variation increased with the increase of trophic level in these reservoirs.     

A New Enantiornithine Bird from the Lower Cretaceous Jiufotang Formation in Jinzhou Area,Western Liaoning Province,China

A new Early Cretaceous enantiornithine bird from Liaoning Province of northeastern China, Shengjingornis yangi, gen. et sp. nov., is reported. This new bird possesses the following unique combination of features: a long rostrum, with some teeth in the front; short nasal; slender jugal; Y-shaped furcula, with expanded distal end of the hypocleidum; cake-like sternum, with a low and caudally distributed keel; strut-like and caudally concave coracoid. The derived features of the scapula and the wings suggest a powerful flapping flight capability.     

船用拖曳绞车抗冲击时域分析

拖曳绞车用于收放水下拖体,是保障水下拖曳系统正常工作的重要装置。参照 BV043 和 GJB1060 标准确定其冲击环境,利用 ABAQUS 有限元软件,采用时域分析方法对拖曳绞车进行有限元计算分析,校核拖曳绞车在受到垂向、横向、纵向 3 个方向冲击载荷作用时的强度。结果表明：拖曳绞车结构所受应力在许用应力范围以内,满足规范抗冲击准则,但不同冲击方向下,最大应力位置不同;安装位置不同,绞车子设备加速度响应规律差异很大,固定安装于支架的控制柜和液压阀组衰减规律明显,悬挂安装的防松马达不易进入稳定状态。     

Characterization of sea ice and its snow cover in the Arctic Pacific sector during the summer of 2016

A comprehensive analysis of sea ice and its snow cover during the summer in the Arctic Pacific sector was conducted using the observations recorded during the 7th Chinese National Arctic Research Expedition(CHIANRE-2016) and the satellite-derived parameters of the melt pond fraction(MPF) and snow grain size(SGS)from MODIS data. The results show that there were many low-concentration ice areas in the south of 78°N, while the ice concentration and thickness increased significantly with the latitude above the north of 78°N during CHIANRE-2016. The average MPF presented a trend of increasing in June and then decreasing in early September for 2016. The average snow depth on sea ice increased with latitude in the Arctic Pacific sector. We found a widely developed depth hoar layer in the snow stratigraphic profiles. The average SGS generally increased from June to early August and then decreased from August to September in 2016, and two valley values appeared during this period due to snowfall incidents.