沉积记录研究的现代过程视角

沉积记录是揭示地球演化的主要数据来源之一,地层学提供了宏观大尺度沉积记录的分析方法,而沉积学则提高了沉积记录的时空分辨率。但上述方法主要是针对沉积体系特征和现象信息的,而有关沉积体系过程和机制信息的提取还较为薄弱。通过评述现代过程在沉积记录研究中的定位,提出了新的科学问题。研究结果表明,基于现代过程研究的勘测性模拟是一种值得追求的方法。经典数值模拟依赖于未知变量与方程个数相同的控制方程,用实测数据作为验证材料,而勘测性模拟是控制方程加工作假说构成的体系,其模型输出指示了过程—产物关系。因此,通过现代沉积体系模拟及其与钻孔资料的对比,可以获取沉积记录所含的过程和机制信息。勘测性模拟也是地球久远时代沉积记录的潜在分析工具。     

Dam-break risk analysis of the Attabad landslide dam in Pakistan and emergency countermeasures

The Attabad landslide dam caused significant property losses and many human casualties in Pakistan, and also greatly affected the operation of the China-Pakistan Karakoram Highway (KKH). This paper discusses the risk of dam breach and hazards to the KKH project construction site following a dam breach. The paper examines the following three topics. (1) The geomorphologic dimensionless blockage index (DBI) and the analogy method were used to analyze the stability of the Attabad landslide dam. The long-term behaviors of landslide dams downstream of the Attabad landslide dam indicate that the risk of a dam breach exists, but the probability of a total dam failure is low. (2) The peak discharge of a potential breach of the Attabad landslide dam was calculated for scenarios in which 1/4, 1/3, 1/2, and total failure of the dam was breached. The potential breach discharge decreases with the downstream distance. (3) The potential impacts of the landslide dam breach on the KKH project construction site were analyzed. Based on the composition of the landslide dam, the probability of a 1/3 dam breach is high. To ensure the safety of downstream areas, disaster preparedness plans that correspond to the 1/2 dam breach scenario should be developed. Based on experience in addressing the landslide dam that was caused by the Wenchuan Earthquake, artificial controlled drainage measures are suggested and provide a technical reference for addressing the Attabad landslide dam and achieving recovery and normal operation of KKH.     

Trace metal anomalies in bleached <Emphasis Type="Italic">Porites</Emphasis> coral at Meiji Reef,tropical South China Sea

Coral bleaching has generally been recognized as the main reason for tropical coral reef degradation, but there are few long-term records of coral bleaching events. In this study, trace metals including chromium (Cr), copper (Cu), molybdenum (Mo), manganese (Mn), lead (Pb), tin (Sn), titanium (Ti), vanadium (V), and yttrium (Y), were analyzed in two Porites corals collected from Meiji Reef in the tropical South China Sea (SCS) to assess differences in trace metal concentrations in bleached compared with unbleached coral growth bands. Ti, V, Cr, and Mo generally showed irregular fluctuations in both corals. Bleached layers contained high concentrations of Mn, Cu, Sn, and Pb. Unbleached layers showed moderately high concentrations of Mn and Cu only. The different distribution of trace metals in Porites may be attributable to different selectivity on the basis of vital utility or toxicity. Ti, V, Cr, and Mo are discriminated against by both coral polyps and zooxanthellae, but Mn, Cu, Sn, and Pb are accumulated by zooxanthellae and only Mn and Cu are accumulated by polyps as essential elements. The marked increase in Cu, Mn, Pb, and Sn are associated with bleaching processes, including mucus secretion, tissue retraction, and zooxanthellae expulsion and occlusion. Variation in these trace elements within the coral skeleton can be used as potential tracers of short-lived bleaching events.     

黄土高原植被降水利用效率对植被恢复/退化的响应

基于2000-2014年MODIS NDVI数据及气象数据,运用累计降水利用效率变化差异（CRD,cumulative rain use efficiency differences）估算模型和基于地形要素降水量插值法,探讨2000-2014年黄土高原RUE（降水利用效率rain use efficiency）对植被变化的响应,以期为黄土高原生态可持续发展提供数据支撑。结果表明：黄土高原大部分地区植被覆盖得以改善,其面积约占总面积的81%,区域边缘植被覆盖退化严重。黄土高原降水利用效率RUE与累计NDVI的相关性总体表现为“东南呈正相关,西北为负相关”的空间格局,全区相关系数以正相关为主。黄土高原CRD与植被变化趋势的相关性显著,其中,植被退化背景下,植被退化程度越严重,RUE越低;植被恢复背景下,RUE受“退耕还林还草”作用显著,2000-2005年,RUE呈上升趋势,2007年后,随着退耕还林还草政策的工作重心转移,RUE呈波动变化。     

川西北高寒沙化草地有机氮组分特征

通过野外调查,结合土样采集及室内分析（Bremner法）,研究了川西北不同程度沙化草地（未沙化、轻度沙化、中度沙化、重度沙化、极重度沙化）不同土层（0～20、20～40、40～60、60～80、80～100 cm）的有机氮组分特征。结果表明：随着草地沙化程度的提高,不同土层的土壤有机氮组分含量均呈下降趋势,其中0～20 cm土层变化最明显,土壤酸解全氮（TAHN）、非酸解氮（NAHN）、酸解氨态氮（AN）、氨基酸态氮（AAN）、氨基糖态氮（ASN）、未知态氮（HUN）含量降低幅度分别为90.58%、69.28%、91.44%、91.01%、87.77%、88.99%;与未沙化草地相比,极重度沙化草地有机氮组分含量显著降低,且下降幅度呈现出AAN> AN> HUN> ASN> NAHN特征,表明AN、AAN较ASN、HUN、NAHN对生态环境变化更为敏感;不同沙化阶段土壤有机氮组分含量降低幅度存在较大差异,但均呈现出沙化前期降幅相对较大,沙化后期降幅相对较小的变化特征,表明草地沙化前期土壤有机氮素流失更为严重.因此,及时对沙化草地的治理,对于防治沙化草地氮素流失具有重要意义。     

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Analysis of Digital Strong Motion Records of the M_S 8.0 Wenchuan Earthquake by the Network of Shaanxi Province

Records of the May 12,2008 MS8.0 Wenchuan,Sichuan,earthquake from 27 stations of Shaanxi Digital Strong Motion Network are processed and analyzed,including baseline adjustment of acceleration traces,filtering,and calculations of velocities,displacements and acceleration response spectra.The results show that direction energy radiation of the large earthquake and horizontal inhomogeneous medium along the wave traveling path might both have some effect on the scattering degree of the attenuation of PGAH,besides influence of local site conditions.For the same intensity,the ratios of PGA /PGV are commonly small,on average about 5,which indicates that long period components are rich in ground motion.Intensities for most sites of the stations are within Ⅴ～Ⅶ.The larger one among PGAE-W and PGAN-S is quite close to their PGAH,which is less than 10% in relative deviation.The dominated waves are surface waves.The thicker the soil overburden is,the stronger the surface wave will be and the longer the shaking will last.Local site conditions have strong effects on ground motion,especially those of thick sediment filled-in basins,as they can significantly amplify long-period components.     

汤池1号井水氡高值异常原因分析

庐江地震台汤池1号井的水氡测值从2009年4月8开始有小幅趋势性上升,8月4日至8月8日,上升速度加快(8月7日升至11.4 Bq/L),8月19日数值恢复正常。本研究从地震前兆异常落实的角度出发,在仪器运行、观测环境、水文地质、人为因素,仪器标定参数、同一井中其他测项的数据变化、同一地热区其他热水井水样数据的对比等方面进行分析,并结合以往水氡资料的映震实例,初步判定此异常为前兆异常。此项工作对今后异常的判断、识别提供了方法和依据。     

智能化中药资源数据采集系统的设计与实现

近年来, 基于信息技术的智能化数据采集系统在我国资源调查中得到广泛应用。本文将空间信息技术GPS与GIS相结合, 从中药资源外业调查工作外业数据采集和内业数据处理两个关键点出发, 设计实现了智能化中药资源数据采集系统。通过第四次中药资源调查部分省份试点应用, 证明了该系统可大大提高外业调查人员工作效率, 简化了内业的数据整理, 并直接与数据库系统对接。该系统的研发完成为未来中药资源普查外业数据采集与内业数据整理提供了最佳的数据获取方案。     

Multi-agent based modeling of spatiotemporal dynamical urban growth in developing countries: simulating future scenarios of Lianyungang city,China

Urbanization is the most typical form of land use/cover change, and exploration of the driving mechanism of urban growth and the prediction of its future changes are very important for achieving urban sustainable development. In view of the ability of a multi-agent system to simulate a complex spatial system and from the perspective of combining macroscopic and microscopic decision-making behaviors of agents, a spatiotemporal dynamical urban growth simulation model based on the multi-agent systems has been developed. In this model, macroscopic land use planning behaviors implemented by macroagents and microscopic land use selection behaviors autonomously generated by microagents interact within two-dimensional spatial cells. Furthermore, the urbanization process is promoted through joint decision-making by macroagents and microagents. Considering the central region of the coastal industrial city Lianyungang as the study area, we developed three target scenarios on the basis of current trends, economic development priorities, and environmental protection priorities. Moreover, the corresponding urban growth scenarios were simulated and analyzed. The simulation results show that by combining the macroscopic and microscopic decision-making behaviors of agents to simulate spatiotemporal dynamical urban growth based on the multi-agent systems, the proposed model can provide a useful spatial exploratory tool for explaining the driving mechanism of urbanization and providing decision-making support for urban management.