Assessment of macrobenthic community function and ecological quality after reclamation in the Changjiang (Yangtze) River Estuary wetland

An ecological optimization project (semi-closed reclamation project) was implemented to control the invasion of Spartina alterniflora, and optimize the habitat of the Chongming Dongtan wetland, in the Changjiang (Yangtze) River Estuary. After project implementation, a macrobenthic ecological survey was conducted in a natural tidal flat and a semi-closed reclamation restoration area within the Chongming Dongtan wetland from 2019 to 2020. Compared with historical data before reclamation, findings showed that the groups, numbers, and species diversity of the macrobenthos increased significantly, and the ecological optimization project resulted in good ecological benefits. In addition, compared to the natural tidal flat, the number of collected macrobenthic phyla, and the macrobenthic density and biomass were significantly lower in the restoration area. Furthermore, the biodiversity index and functional redundancy of natural tidal flats were generally higher, indicating that the community composition and function of natural tidal flats were relatively more stable. Even though the species composition differed between a number of restoration areas and natural tidal flats, there was no difference in functional diversity, indicating that the effect of restoring ecological functions in restoration areas was optimal. Among them, the biodiversity and functional redundancy of Site S2 were significantly reduced, and the ecosystem function was extremely unstable. Habitat heterogeneity, vegetation community and decreasing salinity were the main factors that affected the ecological functions of macrobenthos. The ecological quality was also evaluated; the Transects N3 and N4 showed good quality. The overall ecological quality of the restoration area was generally high, but that of Site S2 was poor and that of Site S2E was merely good, which was mainly due to modifications of the ecological function of macrobenthos. It is suggested that reeds mowing and freshwater species release should be adopted in restoration areas to improve the community function and the environmental disturbance resistance of the macrobenthos.     

Modeling-Based Multiscale Deep Prospectivity Mapping: A Case Study of the Haoyaoerhudong Gold Deposit,Inner Mongolia,China

The mineral system modeling approach for prospectivity mapping is an efficient and economic method to assess undiscovered mineral potential quantitatively. It is a procedure of modeling, acquiring, and coupling the proxies of footprints of mineral systems at multiple scales (e.g., regional, district, and deposit scales). In this approach, the critical issue from multiple scales is that the data collected are asymmetrical from the superficial to the deep or from mine to its brown fields, so that it is hard to employ and integrate them. To complete this study, firstly, multi-tactic 3D geological modeling methods, including the explicit, the implicit, and inversion, were used to build geological models in the condition of asymmetrical datasets at the deposit and district scales. Secondly, indicators acquired in drill-intensive fields among multisource datasets composed of geology, geochemistry, geophysics and alteration data were transferred to studies in deep and brown fields. Finally, deep (~?1,100 m) and circumjacent potentials of mine were targeted in the Haoyaoerhudong gold deposit situated in the Urad Middle Banner area, Inner Mongolia, which is one of the largest black-rock-series-type gold mines in China. This proposed procedure is more visual, clear, intuitive, and transferable to drive mineral system approach to exploration discovery than previous GIS-based studies.

     

An analysis of drag force on wind of shrubs simulated in a wind tunnel

Shrubs that exert drag force on the wind significantly affect the air–surface interaction in arid and semiarid regions, and some coastal regions where aeolian processes are active. An understanding of the drag force on wind of shrubs provides important information on the dynamics of shrubs in reducing wind erosion, and their geomorphological significances. Thus, we analyzed the drag force and drag coefficient for model shrubs using wind measurements obtained by particle image velocimetry in a scaled wind tunnel simulation. The drag force was found to be a function of wind velocity and shrub density. Both drag force and drag coefficient revealed a critical shrub density of around 0.08. The vertical drag force changed direction when the shrub density became greater or less than the critical density. The drag coefficient increased rapidly with shrub density when the density was below 0.08, but it increased very gently when the density was increased beyond the critical value. The results have an important theoretical significance for our understanding of the dynamics of vegetated dunes and the windbreak mechanism of shrubs.     

The Neoproterozoic continental rift magmatism of the eastern Jiangnan orogen: new evidence from the mafic sheets in northern Zhejiang Province,South China

Massive mafic sheets were recently recognized intruding the Neoproterozoic strata in Fuyang area, eastern Jiangnan orogen. Geochronological, geochemical, and isotopic studies were carried out to understand their mantle source, crust–mantle interaction, and tectonic setting. LA-ICP-MS U-Pb zircon data indicate that the sheets were generated at 808 ± 7 Ma. The mafic sheets consist of two groups: high Ti and low Ti. They are enriched in light rare earth elements (LREE; 3.3–5.3 ppm) and show negligible Eu anomalies (δEu = 0.77–1.12). They also have strong large-ion lithophile element (LILE; Sr, K, Rb, Ba) enrichment, moderately strong high-field-strength element (HFSE) enrichment (except for Nb-Ta depletion), and positive εNd(t) (5.1–9.1). Geochemical and isotopic data indicate that the mafic sheets were generated from a depleted asthenospheric mantle source. The high-Ti mafic sheets have higher HFSE contents and less Nb-Ta depletion than the low Ti series, indicating a lower degree of partial melting and crustal contamination. The mafic sheets grew in a within-plate setting, concurrent with the ~820–750 Ma rifting events in the eastern Jiangnan orogen. They are likely related to the breakup of the Rodinia supercontinent.     

南堡滩海大位移井钻井关键因素优化设计

大位移井钻井实施过程中表现最为突出的问题是摩阻扭矩大,它制约着井眼轨迹的有效延伸,尤其在常规钻完井技术时表现得更为明显。冀东油田近年来基于常规钻完井技术条件下,通过对井眼轨道优化设计、钻具组合优化、摩阻扭矩精细预测与控制、井眼延伸极限评估等方面的精细研究与优化设计,有效地模拟分析和论证了南堡滩海中深层大位移井钻井井筒力学行为,提升了对大位移井钻井实践可行性认识和指导了钻完井方案的设计。在南堡滩海成功实施了几十口水平位移大于3000 m的大位移井,最大水平位移达4940 m,为南堡滩海在常规经济技术条件下大位移井的钻井实施提供了技术支持。     

Migration of induced-infiltration stream water into nearby aquifer due to a transverse horizontal well in loess areas

Analysis of the migration paths of stream water introduced into a transverse horizontal well is important to better understand the interactions between streams and aquifers. This paper presents a method of using particle-tracking techniques to evaluate the transport of stream water that infiltrates through a transverse horizontal well that runs transverse to a stream and extends from the stream banks. By conceptualizing the horizontal well as a discrete pipe network, MODFLOW is coupled with the pipe flow equations that govern the movement of water in the horizontal well, and this coupled seepage-pipe flow model is used to calculate the transient groundwater flow field. MODPATH is then used to record the locations of each of the water particles from the interface between the stream and the aquifer. The path lines, travel times, influence zones and the production of infiltrated stream water are determined to depict the migration process. The results suggest that the infiltrated stream water that originates from different stream transects located upstream and downstream from the horizontal well has different migration characteristics, as does the infiltrated stream water coming from different locations on the same stream transect. Eventually, the pumpage of the horizontal well consists partly of the infiltrated stream water and groundwater inflow from the upstream model boundary. The groundwater enters the horizontal well through the two end segments of the horizontal well, and the infiltrated stream water enters the middle segment of the well. The pumped water is still a mixture of infiltrated stream water and groundwater, even if the pumping lasts for a long period. The hydrochemistry of the infiltrated stream water cannot be simply used to evaluate the hydrochemistry of the water pumped from a transverse horizontal well.     

Experimental study on settling velocity of soil particles in dredged slurry

Studying sedimentation and consolidation of dredged slurry has significant implications to the design of storage yard and subsequent ground improvement. In this study, settling velocity of soil particles in dredged slurry during sedimentation and consolidation processes was investigated using an improved multilayer extraction sampling (MES) method. A series of sedimentation column tests were performed on dredged slurry with three different initial water contents. Distributions of volume of soil particles and density of dredged slurry were first obtained by the MES method, settling velocity of soil particles was then calculated by volume flux function approach. It was found that the density and velocity inflection points can be used to distinguish the settling zone and the consolidation zone. The experimental results reveal that the velocity of soil particles was quite low and monotonically decreased with sedimentation height at low initial water content throughout the whole test period, whereas it was increased at 0–1 hours and almost remained constant at 1–7 hours in the settling zone at high initial water content. The effects of initial water content on sedimentation and consolidation mode of dredged slurry and the settling velocity of soil particles were discussed. The relationship between settling velocity of soil particles and particle diameter was also studied. It is indicated that the measured velocity of soil particles was much lower than that calculated by the Stokes equation, and it was related to 0.4881–0.5906 order of particle diameter at 0–1 hours and 0.1117–0.1825 order of particle diameter at 1–7 hours for the test slurries.     

汉江上游郧县庹家湾剖面光释光测年及意义

在野外考察基础上选择湖北郧县庹家湾剖面为研究对象。在对磁化率和粒度进行分析的同时,用单片再生剂量法进行了光释光测年（OSL）地层断代。OSL测年数据显示：剖面样品年龄处在55.11~13.57 ka BP,且与地层深度呈现出良好的对应关系,此剖面为黄土风化堆积形成。黏粒含量、黏粒/粉砂值以及磁化率值等气候替代性指标数值在马兰黄土层228~260 cm和294~370 cm深度明显高于典型马兰黄土（L₁）,具有明显的成壤特征,通过OSL测年数据判断时间为27.26~21.59 ka BP,说明在晚更新世时期气候并非持续稳定的寒冷干旱,而是具有一定的波动,在此期间气候相对温暖湿润,而且此次气候事件在黄土高原地区其他沉积记录中也有良好记录。     

磴口县景观格局演变特征及生态网络构建

城市生态基础设施是城市可持续发展的基础,西部干旱区生态脆弱性大,县域尺度的生态基础设施网络是保证干旱区城市稳定与发展的重要保障。在快速城市化的背景下,选择西部典型生态脆弱区磴口县为研究区,运用景观格局指数、景观转移网络及核密度分析等方法,分析景观格局演变,在此基础上确定生态源地并分级,基于Cost Path模型提取生态廊道与生态节点,构建城市化背景下基于景观格局演变的磴口县生态基础设施网络。结果表明：2014年磴口县域景观破碎化程度高,景观生态流流动性差,城市与建设用地、荒漠灌木林地、耕地、沙漠之间的转移情况决定了磴口县整体景观变化的特征,2001-2014年共存在28种景观转移关系;基于Cost Path模型构建的县域尺度生态基础设施优化网络共包含391块生态源地、47 466条生态廊道和799个生态节点。针对干旱区构建的县域尺度的城区防护型生态网络,能够为磴口县城市化发展提供重要保障,对干旱区城市生态规划具有重要的参考价值。     

烟台三菱水泥有限公司燕地石灰石矿山资源综合利用情况分析

烟台三菱水泥有限公司燕地石灰石矿,位于山东省栖霞市臧家庄镇燕地村东。矿山南北长约1000m,东西宽300～500m,属水泥厂石灰石原料专用矿山,矿山固定资产1．32亿元,各类机械设备以进口为主,功能齐全,性能优良。矿山总体为凹陷露天开采,公路运输开拓,开采工艺为：钻孔→爆破→采装→运输→破碎→均化堆积。采用垂直走向拉开段沟,水平分层,由上而下的开采方法,台段高度10m,同时生产的平台2～3个。