潮滩冲淤扰动下外来与乡土红树植物幼苗稳定性差异

引种外来树种是我国各地在红树林修复实践中常用的措施。由于更容易在困难立林地存活, 外来树种被认为更具竞争优势。为弄清外来与乡土红树植物物种在困难立林地存活能力的差异及其原因, 本研究选取典型外来引种先锋树种拉关木(Laguncularia racemosa)与乡土先锋植物白骨壤(Avicennia marina)为研究对象, 通过控制实验探究潮滩冲淤扰动条件下幼苗稳定性差异及其形成机制。结果表明, 幼苗抗侵蚀能力与幼苗根冠比显著正相关, 泥沙淤积抑制幼苗根系生长, 而底床侵蚀则促进根系伸长。与白骨壤相比, 拉关木幼苗的主根更长, 根冠长度比更大, 更能抵抗底泥的侵蚀扰动, 且通过根系伸长以增强幼苗稳定性的能力也更强。拉关木幼苗比白骨壤更能适应潮滩冲淤扰动, 其竞争优势从幼苗阶段就已经建立。本研究结果可为红树林修复实践中树种和宜林地的选择提供参考, 亦可为评估外来红树物种入侵风险评价提供依据。     

Identification of optimal strategies for agricultural nonpoint source management in Ulansuhai Nur watershed of Inner Mongolia,China

In this study, an environmental-friendly modeling system was developed and applied to an agriculture nonpoint source (AGNPS) management in Ulansuhai Nur watershed. In this system, water environmental capacity, credibility-based chance-constrained programming (CCCP), and AGNPS optimization models were integrated into a general modeling framework. It could be used to calculate water environmental capacity of total nitrogen and total phosphorus in Ulansuhai Nur watershed, which could consequentially provide input data for the developed AGNPS optimization model. Also, the inherent uncertainties in estimating water environmental capacities that can be expressed as possibilistic distributions were reflected and addressed based on computational results of three widely used methods. Such uncertainties were consequentially transferred to the proposed CCCP model based on the adoption of multiple credibility satisfactory levels, significantly facilitating objectivity reflection of decision alternatives. The developed modeling system was then applied to Ulansuhai Nur watershed of Inner Mongolia, a semi-arid river basin in northwestern China. Optimal strategies for AGNPS management in Ulansuhai Nur watershed were generated with consideration of the maximum total agricultural income under multiple policy scenarios. The results showed that the total agricultural income would increase with point source pollution being cut down, and would decrease with rising credibility levels, representing decreasing system violation risks. It was indicated that the higher of total nitrogen/phosphorus discharge being less than water environmental capacity of Ulansuhai Nur, the lower the total agriculture incomes. The proposed methods could help decision makers establish various production patterns with cost-effective agriculture nonpoint source management schemes in the basin of Ulansuhai Nur, and gain in-depth insights into the trade-offs between total agricultural incomes and system reliabilities.     

四川盆地中二叠统茅口组米兰科维奇旋回及高频层序

四川盆地中二叠统茅口组形成于中二叠世中晚期。通过分析四川盆地中二叠统茅口组露头剖面岩性特征、对比广元上寺长江沟露头剖面碳氧同位素变化趋势与沉积层序发育特征,将茅口组划分为2个可全盆地追踪的Ⅱ型三级层序,并分析了茅口组三级层序的主控因素。在此基础上,对钻穿中二叠统茅口组典型井的自然伽马能谱测井曲线开展频谱分析,识别出多种具有米兰科维奇旋回特征的高频旋回,并计算出茅口组沉积的平均速率及沉积时限等相关参数。最后,采用数字滤波消除掉其他次要旋回因素的影响而仅保留与主控因素相关的旋回信息,建立茅口组的高频层序划分方案。结果表明,茅口组三级层序在形成过程中主要受控于构造升降及全球海平面变化;茅口组米兰科维奇旋回特征明显,其中长偏心率旋回(413.0 ka)和短偏心率旋回(123.0 ka)分别是形成四级层序(准层序组)和五级层序(准层序)的主控因素,与之对应的平均旋回厚度在龙17井区分别为13.44m和4.31m,在安平1井区分别为16.03m和4.68m;茅口组大约发育15个四级层序,其发育时限大约为6.11Ma;根据构造背景曲线和长偏心率旋回曲线的叠加曲线划分高频层序,其高频层序界面更加接近实际地层的发育情况。     

海底热液多金属硫化物分布及控矿因素

基于最新公布的全球热液矿点数据讨论了海底热液多金属硫化物矿体形成的构造环境,探讨了深部岩浆活动、断裂构造以及沉积物盖层等控矿因素对洋中脊多金属硫化物矿体成矿的影响。研究结果表明:海底热液多金属硫化物矿点主要分布于离散型板块边界和汇聚型板块边界;深部岩浆活动和断裂构造是洋中脊热液多金属硫化物成矿最主要的控矿因素;快、慢扩张洋中脊环境深部岩浆活动和断裂构造的差异导致在海底形成了不同规模的多金属硫化物矿体。对认识海底热液多金属硫化物矿床分布与成矿规律、以及开展海底多金属硫化物资源勘查具有一定的指导意义。     

Assessment of structural stability in Bohai Sea area based on AHP-GDM model

The AHP-GDM model is used for the assessment of structural stability, with the Bohai Sea area as an example. In this model, the credit degree of each expert is calculated through the assessment matrix based on the similarity and diversity of vector. The comprehensive opinions of expert panel are quantitatively obtained by considering the effect of credit degree. According to the geological structural setting, the Bohai Sea is divided into twelve assessment zones of structural stability by non-uniform element method. The structural stability grade of each zone is obtained on the basis of the latest geophysical data, earthquake statistical data, and the information of fault activities, current stress field and crustal deformation. The results show that there are one relatively stable area, three relatively sub-stable areas, six relatively sub-unstable areas and two relatively unstable areas. The assessment results of non-uniform element method are very close with those of uniform grid method with size of 0.25° in longitude direction and 0.14° in latitude direction. However the workload of non-uniform element method is only 1/16 of the latter. Compared with traditional assessment methods of structural stability, a more objective and reliable assessment result can be obtained by combining non-uniform element method and AHP-GDM model.     

城市气候承载力定量化评价方法初探

本文从气候天然容量、城市气候压力和城市协调发展能力3个方面选取24个指标构建较完整的城市气候承载力评价指标体系。气候天然容量指数采用内梅罗指数法计算,城市气候压力指数和城市协调发展能力指数采用基于熵权的综合评价方法计算,进而构建城市气候承载力综合评价函数以量化评价结果。以上海市为例,对其气候承载力进行定量化评价。研究表明,本文建立的气候承载力评价指标体系是可行的,它可以描述某一城市时域上的变化,也可以对区域气候承载力开发利用过程中存在的问题进行甄别,并可作为气候预警响应的依据,为我国建立区域气候安全管理机制提供技术参考。分析上海市2004-2013年这10年间气候承载力的变化趋势,结果表明研究期内上海市气候承载力整体劣于基准年值,且因深受气候天然容量的影响而处于较大波动状态。     

江南造山带石耳山新元古代花岗岩的构造变形、LA-ICP-MS锆石U-Pb年龄及其地质意义

在江南造山带的东段皖浙赣交界地区发育一系列花岗岩岩体,区域上,岩体呈条带状,NE—SW向雁行排列,平行于赣东北断裂带分布;微观下,岩浆流动组构残迹、蠕英石的普遍发育及固态塑性变形证明了该地区岩体变形经历了从岩浆—亚岩浆—固态变形的一个持续转变的过程;岩体锆石年龄与邻区岩体的变质变形年龄有很好的耦合性。由此可见研究区变形花岗岩体为同构造花岗岩,是岩浆在侵位冷凝过程中受到赣东北断裂带强烈构造作用影响的产物。LA-ICP-MS锆石U-Pb同位素定年结果表明:灵山岩体形成于783±14 Ma;莲花山岩体形成于780±12 Ma,属于新元古代岩浆活动。扬子板块与华夏板块碰撞导致江南造山带新元古界的岩群普遍遭受区域变质、变形作用,同构造花岗岩的构造变形特征正是区域构造变形的表现,因此该同构造岩体的年龄可能作为扬子板块与华夏板块仍在挤压、碰撞的年代学证据。     

声学探测技术在近岸水域地震地层探测中的应用

对山东省海阳冷家庄东南近岸海域浅、中深层地层声学探测剖面进行了分析对比,对研究区内的地震地层层序和基岩的构造特征地判有研究区存在着３个地震反射波且,分别代表了３套没形成时代、不同 地层,综合海底浅层柱状取样结果及陆上地层露头情况,推测这３个地震反射波层组分别与第四纪浅海相泥砂质沉积,白垩纪莱阳群中上部的中、薄层粉砂岩和莱阳群的厚层石英砂岩相对应。并且,发育于基岩内的断层构造在第二、三反射波层组内具     

Risks of airborne pollution accidents in a major conurbation: case study of Zhangjiakou,a host city for the 2022 Winter Olympics

The number of airborne pollution accidents is second only to that of water-borne pollution accidents, in recorded environmental disasters. Acute casualties and public health costs have prompted many airborne pollution risk analyses. To date, few assessment methods have been carried out at regional-scale to quantify acute airborne pollution risk. Herein, a Hybrid Simulation and Risk Analysis approach, involving a systematic combination of simulation, risk ranking, and standardized analysis, is proposed at regional scale. Gaussian and heavy-gas models are utilized in the simulation process, and acute exposure limits preferentially adopted in the risk analysis. The case study shows that 34 of 243 townships in Zhangjiakou City of north China, one of the twin cities selected to host the 2022 Winter Olympics, are threatened by airborne risk sources. It is found that the accidental air pollution risk is comparatively higher in the Xuanhua and Wanquan conurbations. High-risk chemical enterprises (312–432 risk scores) are mostly located near urban areas with high population density where many people are vulnerable receptors to potential air pollution accidents. The resulting risk map indicates that acute airborne pollution from Zhangjiakou would not be a threat either to the proposed Olympic site at Chongli or to downwind Beijing.