基于LiDAR的海原断裂松山段断错地貌分析与古地震探槽选址实例

基于高精度机载Li DAR数据在GIS平台的地貌因子渲染分析,对海原断裂老虎山段松山地区古地震研究点进行高精度大比例尺(1∶1000)地貌填图,勾勒出研究点微地貌空间展布和断裂高精度几何形态。通过对松山古地震研究点2个新探槽的开挖,结合细致的探槽解译、地震事件识别与分期、年代学样品测试,得出5次37380±880BP以内的不连续古地震序列。通过对比此处已经开挖的各自相距不足150m、分布于断裂同一段落的4个古地震探槽的微地貌位置、沉积特征和地震事件信号强弱,发现即使相距不远,不同微地貌位置古地震探槽揭示的古地震现象也会有显著差别。这种差别凸显了古地震研究结果,如揭示的事件证据和个数等与探槽点位置的选取有较强的依赖性。综合对比分析表明,较低的地势、低能静水环境、高沉积速率、细粒的沉积物源区及连续的沉积环境是走滑断裂上开展古地震研究的优选地貌位置。实例表明,基于高精度地形数据对研究点开展精细地貌填图揭示微地貌时空演化,从而在探槽开挖前对古地震研究点的构造地貌优劣进行充分评价是提高古地震研究质量的必要程序,同时也显示出高精度机载Li DAR数据在活动构造研究中的重要新应用。     

Groundwater vulnerability assessment based on modified DRASTIC model: a case study in Changli County,China

Groundwater vulnerability assessment has been regarded as the initial step to understand and evaluate the susceptibility of the subsurface to contamination. As one of the most widely used models, the DRASTIC has been applied worldwide. However, problems associated with the model, such as the subjectivity in rating and weighting schemes, have led to modified versions of this model for better representing the vulnerability of the aquifer. In this study, a modified DRASTIC model was formulated by adjusting the rating and weighting scores based on Wilcoxon rank-sum test and Analytic Hierarchy Process. The modified model was then applied to the evaluation of groundwater vulnerability in Changli County, China in a GIS environment. The validity of the model was verified by analysing the correlation coefficient between the vulnerability index and the nitrate concentration. The results revealed that the modified DRASTIC model presents stronger correlation with the nitrate contamination than the traditional DRASTIC model.     

Numerical study of the storm-induced circulation on the Scotian Shelf during Hurricane Juan using a nested-grid ocean model

A nested-grid ocean circulation modelling system is used to assess the upper ocean response of the Scotian Shelf and adjacent slope to Hurricane Juan in September 2003. The nested-grid system consists of a fine-grid inner model covering the Scotian Shelf/slope and a coarse-grid outer model covering the northwest Atlantic Ocean. The model-calculated upper ocean response to Hurricane Juan is characterized by large divergent surface currents forced by the local wind forcing under the storm, and intense near-inertial currents in the wake of the storm. The sea surface temperature (SST) cooling produced by the model is biased to the right of the storm track and agrees well with a satellite-derived analysis. Over the deep water, off the Scotian Shelf, some of the near-inertial energy input by the storm is advected eastward by the Gulf Stream away from the storm track. The hurricane also generates shelf waves that propagate equatorward with the coastline on their right. In comparison with the outer model results, the inner model captures more meso-scale structures, greater SST cooling and stronger near-inertial currents in the study region.     

桂中坳陷北部下石炭统页岩储层微观孔隙结构特征

正页岩储层的孔隙结构特征对页岩气的富集具有重要影响(Loucks et al., 2007;胡宗全等,2015)。我国广西桂中地区页岩气储集孔隙精细表征的研究尚处于空白状态(毛佩筱,2018),为了推进桂中地区上古生界的页岩气勘探工作,本次研究从岩石矿物成分、有机质含量及其演化、物性、储集空间等方面,对桂中地区鹿寨组页岩气储集孔隙进行精细表征,以期为今后的页岩气勘探开发提供参考。     

浅论地震震源区及地震动力源

根据超深钻探的初步成果，提出大陆壳内高温、高压的水压破裂带是地壳内最危险的震源区，同时认为地幔波动是地震的根本动力源。     

A two-way nested-grid ocean-circulation model for the Meso-American Barrier Reef System

A two-way nested-grid ocean-circulation model is developed for the Meso-American Barrier Reef System (MBRS), using a newly developed two-way interactive nesting technique. The unique feature of this new nesting technique is its use of the semi-prognostic method (Sheng et al. 2001) to exchange information between different grids through the model momentum equations. The nested-grid model for the MBRS has a fine-resolution inner model embedded in a coarse-resolution outer model. The outer model is the western Caribbean Sea model developed by Sheng and Tang (2003), with a horizontal resolution of roughly 19 km. The inner model domain covers the northwest Caribbean Sea (NWCS) between 79°W and 89°W and between 15.5°N and 22°N, with a horizontal resolution of roughly 6 km. The nested-grid ocean model is initialized with the January mean temperature and salinity and forced by the monthly mean COADS (comprehensive ocean-atmosphere data set) wind stress and surface heat flux. The model sea-surface salinity is restored to the monthly mean climatology. The nested-grid model is integrated for 2 years and the second-year model results are presented in this paper. The model-calculated annual-mean near-surface currents over the NWCS agree reasonably well with the time-mean near-surface currents inferred by Fratantoni (2001) from trajectories of the satellite-tracked 15-m drogued drifters in the 1990s. The two-way nested model is also used to quantify the role of local wind stress, local density gradients and boundary forcings of the outer model in driving the annual-mean circulation in the region.Responsible Editor: Phil Dyke     

A new two-way nesting technique for ocean modeling based on the smoothed semi-prognostic method

A new two-way nesting technique is presented for a multiple nested-grid ocean modeling system. The new technique uses the smoothed semi-prognostic (SSP) method to exchange information between the different subcomponents of the nested-grid system. Four versions of the new nesting technique are described, together with conventional one-way nesting. The performance of the different nesting techniques is compared, using two independent nested-grid modeling systems, one for the Scotian Shelf of the northwest Atlantic Ocean and the other for the Meso-American Barrier Reef System of the northwestern Caribbean Sea. Nesting using the semi-prognostic method is shown to effectively prevent unrealistic drift of the inner model, while use of the SSP method avoids unnecessary damping of small scales on the inner model grid. Comparison of the annual-mean flow field with the near-surface currents determined by Fratantoni (in J Geophys Res 106:2977–2996, 2001) from observed trajectories of near-surface drifters demonstrates the overall superiority of the nesting technique based on the SSP method.     

康定榆林宫水热区CO_2研究

本文探讨康定榆林宫水热区水热ＣＯ２气的来源、区内主要水热点的ＣＯ２气释放强度及释放模式。稳定同位素分析结果表明,该水热区水热ＣＯ２气为深部成因,且有６０％以上为变质成因;估算得区内主要水热点的ＣＯ２气释放强度为１０８ｇ／ａ。结合研究区地质条件做出了水热ＣＯ２气释放模式示意图。     

Pollution characteristics and risk assessment of organophosphate esters in aquaculture farms and natural water bodies adjacent to the Huanghe River delta

To date, little attention has been paid to the effects of organophosphate esters (OPEs) pollution on aquacultural environment and aquatic product safety. Huanghe (Yellow) River delta area is one of the largest aquaculture centers in China, where ecological security protection is crucial in the national strategy of China. To explore the pollution characteristics, bioaccumulation, and health risks of OPEs in aquaculture farms in the Huanghe River delta and natural water bodies in the adjacent seas, five species of organisms from different farm types nearby the Huanghe River delta, and the corresponding culture water and sediments were sampled in this study. The total concentrations of ∑₁₃OPEs in water, sediments, and organisms were 51.53–272.18 ng/L, 52.63–63.17 ng/g dry weight (dw), and 46.82–108.90 ng/g dw, respectively. Among the five types of culture ponds, the water samples from the swimming crab and hairy crab culture ponds exhibited higher OPEs, the concentration of OPEs in the sediments from the few ponds was relatively balanced, and the OPEs in the organism from the holothurian ponds was higher. Tris (1,3-dichloro-2-isopropyl phosphate) (TDCP) was the main contaminant in water samples and tripropyl phosphate (TPrP) in sediments and organisms. However, trisphenyl phosphate (TPhP) showed the strongest bioaccumulation ability, followed by 2-ethylhexyl diphenyl phosphate (EHDPP) and TPrP. The bioaccumulation capacities of the five species were as follows: prawn > holothurian > hairy crab > swimming crab > carp. These five types of organisms, as main seafood in human consumption, were at low risk of negative impacts of pollution. However, the risk from the mixture of organophosphate flame retardants (OPFRs) still requires more attention due to the increasing consumption and production in the world.

     

Development of a High-Resolution Coastal Circulation Model for the Ocean Observatory in Lunenburg Bay

An advanced ocean observatory has been established in Lunenburg Bay of Nova Scotia, Canada as part of an interdisciplinary research project of marine environmental prediction. The development of a high-resolution coastal circulation model is one of important components of the observatory. The model horizontal resolution is 60m and the vertical resolution is about 1 m. The coastal circulation model is used to simulate the semi-diurnal tidal circulation and associated nonlinear dynamics with the M2 forcing specified at the model open boundaries. The model is also used to simulate the storm-induced circulation in the bay during Hurricane Juan in September 2003, with the model forcing to be the combination of tides and remotely generated waves specified at the model open boundaries and wind stress applied at the sea surface. The model results demonstrate strong interactions between the local wind stress, tidal forcing, and remotely generated waves during this period. Comparison of model results with the surface elevation and current observations demonstrates that the coastal circulation model has reasonable skills in simulating the tidal and storm-induced circulation in the bay.