Bioacoustic application on fisheries management in an artificial reefs’ ecological reserve of Bohai Gulf China

Various techniques have been used in marine fishery resources assessment. Among those, acoustic techniques have high efficiency and wide adaptability, and are environment friendly. Therefore, acoustic techniques played a key/indispensable role in the field of ecosystem-based fishery management. Acoustic surveys were conducted during the wet (May) and dry (November) seasons in 2016 in the artificial reefs ecological reserve of Bohai Gulf and a nearby control region to understand the current situation of fishery resources and explore the effectiveness of underwater artificial constructions by a dual-frequency identification sonar (DIDSON) and a scientific split-beam echosounder (120 KHz, Simrad EY60). Fish densities in various seasons and regions showed significant differences and interaction, with a maximum value of 358020.34 ind/n.mile² in the artificial reefs’ region and a minimum value of 71898.35 ind/n.mile² in the control region during the wet season. Fish densities in defined parallel transects revealed a roughly southward migration trend of small-size individuals from wet season to dry season. Single echo detections in the artificial reefs region demonstrated a wider target strength (TS) range (? 60 ~ ? 30 dB vs ? 60 ~ ? 51 dB) and higher mean TS values (? 55.87 dB vs ? 58.31 dB) than the control region both in the wet and dry seasons, which indicated a more complicated and stable fish community structure in the artificial reefs area. The vertical distribution of single echo detections tracked by the echoview post-processing system showed an apparent downward gathering effect. A positive correlation between TS and water depth was discovered from Pearson correlation analysis in the artificial reefs region during the dry season.     

A risk evaluation model for karst groundwater pollution based on geographic information system and artificial neural network applications

The risk analysis on karst groundwater pollution is a research hotspot in current international hydrogeological field as well as the premise of preventing and controlling groundwater pollution. According to the characteristics of groundwater pollution in the typical study area, the study selected main-control factors of risk evaluation on karst groundwater pollution in mountainous areas at first. Based on this, the research determines the method for quantifying the factors and established a risk evaluation index system for karst groundwater pollution. To overcome drawbacks of the method for determining weights of factors in traditional evaluation method, the study determines the structure of the artificial neural network model by combining the selected evaluation factors. And also, the weight coefficients of evaluation factors on each layer are calculated. On this basis, the model for evaluating the risk of karst groundwater pollution is established. Moreover, the risk zoning evaluation map of groundwater pollution in the typical study area is prepared after conducting the weighted stacking of various sub-layers using the geographic information system. The method applied in the study can comprehensively and objectively reflect that the groundwater pollution is controlled by multiple factors and reveal the nonlinear characteristic of the pollution process. Additionally, the evaluation result is institutive and visible, which can provide a certain basis and reference for relevant researches.     

Shale experiment and numerical investigation of casing deformation during volume fracturing

The casing deformation issues have occurred widely in Changning-Weiyuan National Shale Gas Demonstration Area. During multi-stage volume fracturing process, a large amount of fracturing fluid is injected into the formation, leading to tremendous change of stratum property and formation stress field. To assess the influence of shale formation on casing deformation, the acoustic velocity is measured to obtain the shale rock elastic modulus after saturation with water for different times. Then, the three-dimensional physical and finite element models are established using the stage finite element method considering transient thermal-pressure coupling. Shale anisotropy, shale stiffness degradation, and formation slip are taken into account to investigate the influences on casing deformation. Experiment results indicate that shale stiffness degrades dramatically after saturation with water for 24 h. Numerical simulations indicate that the shale modulus degradation mainly leads to large casing stress. Formation slipping not only causes excessive casing stress, but also causes large casing displacement. When slipping distance is larger than 15 mm, casing stress can reach up to the yield stress for P110 grade casing. Meanwhile, the casing deformation will be 14.95 mm, blocking the fracturing tools into the well bottom. Shale anisotropy has a minor influence on casing deformation.     

Quantitative assessment of the impact of an inter-basin surface-water transfer project on the groundwater flow and groundwater-dependent eco-environment in an oasis in arid northwestern China

Inter-basin water transfer projects (IBWTPs) can involve basins as water donors and water receivers. In contrast to most studies on IBWTPs, which mainly impact the surface-water eco-environment, this study focuses on the impacts of an IBWTP on groundwater and its eco-environment in a water donor basin in an arid area, where surface water and groundwater are exchanged. Surface water is assumed to recharge groundwater and a groundwater numerical simulation model was constructed using MODFLOW. The model was used to quantitatively evaluate the impact of an IBWTP located in the upstream portion of Nalenggele River (the biggest river in the Qaidam basin, Northwest China). The impact involved decrease in spring flow, drawdown of groundwater, reduction in oasis area, and an increase in species replacement of oasis vegetation in the midstream and downstream of the river. Results show that the emergence sites of springs at the front of the oasis will move 2–5 km downstream, and the outflow of springs will decrease by 42 million m³/a. The maximum drawdown of groundwater level at the front of the oasis will be 3.6 m and the area across which groundwater drawdown exceeds 2.0 m will be about 59.02 km², accounting for 2.71% of the total area of the oasis. Under such conditions, reeds will gradually be replaced by Tamarix, shrubs, and other alternative plant species. These findings have important implications for the optimization of water resource allocation and protection of the eco-environment in arid regions.     

多枝柽柳(Tamarix ramosissima)根、冠构型的年龄差异及其适应意义

根、冠构型差异是植物研究中容易被忽视的环节,但其在植物适应环境的过程中扮演着重要角色。对不同林龄多枝柽柳(Tamarix ramosissima)根、冠构型参数的调查研究表明:(1)不同林龄多枝柽柳冠层构型有较大的差异,幼年阶段多枝柽柳小枝分枝率和一级分支长度较小,各级分支直径较大,体现了其适应强风、干旱环境的可塑性变化;(2)随着林龄的增加,多枝柽柳分支率、根系连接长度、各级根系长度和直径明显增加,说明不同生长阶段多枝柽柳通过权衡碳消耗和碳分配采取不同的干旱适应策略,进而导致不同生长阶段干旱适应能力的差异;(3)不同林龄多枝柽柳根系拓扑结构参数无明显差异,均接近鲱鱼骨状分布,但根系连接长度差异显著,体现了其干旱适应能力的差异。     

2011年夏季北极王湾细菌群落结构分析及浮游细菌丰度检测

采用PCR-DGGE方法,对2011年夏季北极王湾表层海水及沉积物细菌的群落分析结果表明,沉积物中的细菌多样性指数高于海水。深水站位(S1和S3)的沉积物细菌群落不但与浮游细菌群落存在差异,并且与浅水站位(S5)也存在差异。位于湾口、湾内的浮游细菌群落组成也存在一定差异。测序结果显示,王湾海洋细菌的多样性组成包括α-变形细菌、γ-变形细菌、δ-变形细菌、放线菌、拟杆菌及厚壁菌等类群。基于定量PCR方法的检测结果表明,位于湾口、湾内的浮游细菌丰度相似,但湾内玫瑰杆菌支系的丰度明显低于湾口。研究结果表明,与湾口相比,王湾湾内的细菌群落受陆源性淡水输入的影响明显,不但表现在细菌群落的多样性组成上,也表现在某些特定细菌类群的数量分布上。     

Anisotropic attenuation of stratified viscoelastic media

An important cause of seismic anisotropic attenuation is the interbedding of thin viscoelastic layers. However, much less attention has been devoted to layer‐induced anisotropic attenuation. Here, we derive a group of unified weighted average forms for effective attenuation from a binary isotropic, transversely isotropic‐ and orthorhombic‐layered medium in the zero‐frequency limit by using the Backus averaging/upscaling method and analyse the influence of interval parameters on effective attenuation. Besides the corresponding interval attenuation and the real part of stiffness, the contrast in the real part of the complex stiffness is also a key factor influencing effective attenuation. A simple linear approximation can be obtained to calculate effective attenuation if the contrast in the real part of stiffness is very small. In a viscoelastic medium, attenuation anisotropy and velocity anisotropy may have different orientations of symmetry planes, and the symmetry class of the former is not lower than that of the latter. We define a group of more general attenuation‐anisotropy parameters to characterize not only the anisotropic attenuation with different symmetry classes from the anisotropic velocity but also the elastic case. Numerical tests reveal the influence of interval attenuation anisotropy, interval velocity anisotropy and the contrast in the real part of stiffness on effective attenuation anisotropy. Types of effective attenuation anisotropy for interval orthorhombic attenuation and interval transversely isotropic attenuation with a vertical symmetry (vertical transversely isotropic attenuation) are controlled only by the interval attenuation anisotropy. A type of effective attenuation anisotropy for interval TI attenuation with a horizontal symmetry (horizontal transversely isotropic attenuation) is controlled by the interval attenuation anisotropy and the contrast in the real part of stiffness. The type of effective attenuation anisotropy for interval isotropic attenuation is controlled by all three factors. The magnitude of effective attenuation anisotropy is positively correlated with the contrast in the real part of the stiffness. Effective attenuation even in isotropic layers with identical isotropic attenuation is anisotropic if the contrast in the real part of stiffness is non‐zero. In addition, if the contrast in the real part of stiffness is very small, a simple linear approximation also can be performed to calculate effective attenuation‐anisotropy parameters for interval anisotropic attenuation.     

“援印尼地震监测台网”快速测定印尼7.0级地震

北京时间2013年4月6日12时42分,印度尼西亚伊里安查亚地区发生7.0强烈地震,“援印尼地震监测台网(ICDSN)”对此次地震进行了快速、准确的自动测定.本文简要介绍了援建台网的基本情况,并对此次地震的自动定位结果进行了比对分析.     

Toxic metal contamination and distribution in soils and plants of a typical metallurgical industrial area in southwest of China

In this work, the total and each fraction concentration of toxic metals (Pb, Zn, Cu and Cd) in soils as well as in plants from a typical metallurgical industrial area in southwest of China were determined. The obtained experimental results demonstrated that the total toxic metal content in contaminated soils was in the order of Zn > Pb > Cu > Cd. Modified microwave-assisted extraction showed that the distributions of each fraction of toxic metals in soils were different and some soil properties may play a role in the fraction distributions. The content of Cu, Zn, Cd and Pb in different vegetables ranged from 9.82 ± 1.02 to 39.3 ± 1.13 mg kg^?1, 1,321 ± 10.50 to 3,153 ± 11.30 mg kg^?1, 4.47 ± 0.21 to 18.9 ± 0.37 mg kg^?1 and 28 ± 1.2 to 102 ± 1.5 mg kg^?1, respectively. And the accumulation of toxic metals in plants was in the order of Cd > Zn > Cu > Pb. The bioconcentration factor (BCF) values of Cd, Zn, Cu and Pb in the different tissues of plants were in the range of 0.03–0.43, 0.027–0.35, 0.014–0.12 and 0.004–0.051, respectively. The distribution of each toxic metal in plants indicated that the ability for plants to accumulate toxic metals in different tissues followed the sequence of leaf > stem.     

Petrogenesis of the Yangchang Mo‐bearing granite in the Xilamulun metallogenic belt,NE China: geochemistry,zircon U–Pb ages and Sr–Nd–Pb isotopes

The Yangchang granite‐hosted Mo deposit is typical of the Xilamulun metallogenic belt, which is one of the important Mo–Pb–Zn–Ag producers in China. A combination of major and trace element, Sr, Nd and Pb isotope, and zircon U–Pb age data are reported for the Yangchang batholith to constrain its petrogenesis and Mo mineralization. Zircon LA‐ICPMS U–Pb dating yields mean ages of 138 ± 2 and 132 ± 2 Ma for monzogranite and granite porphyry, respectively. The monzogranites and granite porphyries are calc‐alkaline with K₂O/Na₂O ratios of 0.75–0.92 and 1.75–4.42, respectively. They are all enriched in large‐ion lithophile elements (LILEs) and depleted in high‐field‐strength elements (HFSEs) with negative Nb and Ta anomalies in primitive‐mantle‐normalized trace element diagrams. The monzogranites have relatively high Sr (380–499 ppm) and Y (14–18 ppm) concentrations, and the granite porphyries have lower Sr (31–71 ppm) and Y (5–11 ppm) concentrations than those of monzogranites. The monzogranites and granite porphyries have relatively low initial Sr isotope ratios of 0.704573–0.705627 and 0.704281, respectively, and similar ²⁰⁶Pb/²⁰⁴Pb ratios of 18.75–18.98 and 18.48–18.71, respectively. In contrast, the ε_Nd(t) value (−3.7) of granite porphyry is lower than those of monzogranites (−1.5 to −2.7) with Nd model ages of about 1.0 Ga. These geochemical features suggest that the monzogranite and granite porphyries were derived from juvenile crustal rocks related to subduction of the Paleo‐Pacific plate under east China. Copyright © 2013 John Wiley & Sons, Ltd.