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61.
Tropical seagrass decline and recovery from severe storm impacts was assessed via quarterly measurements of seagrass biomass, species composition and experimental investigations of recovery in north Queensland. Shallow and deep seagrass meadows suffered major declines. Significant recovery in the two years following loss only occurred at deeper sites. Halophila spp. in deep water areas had a high capacity for recovery through the availability of seed banks. In contrast, the shallow species did not recover quickly from experimental disturbance, had poor seed reserves and relied on asexual propagation. The potential for shallow species to recover rapidly from widespread losses was limited as seed banks were limited or non-existent. Understanding inter- and intra-specific differences in seagrass recovery and how this interacts with location is critical to predict the consequences of climate events to tropical seagrasses. This is especially important as more frequent severe storms are predicted as a consequence of climate change.  相似文献   
62.
This study explored how Territorial Use Rights for Fisheries (TURFs) functioned during the recovery from the devastating tsunami disaster which struck the Sanriku region in 2011, with a focus on abalone harvest, which is the most profitable resource managed by TURFs. During the winter of 2011–2012, only 36 of 51 managing bodies could harvest abalones because of a great shortage of boats. Recourse degradation was also feared, and the harbors were badly damaged. Of 27 managing bodies whose harvesting methods were known, 22 harvested collectively. Abalones are traded at high price and harvesting them requires skill; hence, it has always been done individually and competitively; collective harvesting conducted during this season was therefore quite exceptional. Eighteen managing bodies also handled distribution of the harvest, adopting flexible measures according to each community's circumstances. The collective action ended immediately after the urgent shortage of boats was alleviated. The diversity of natural resources managed by TURFs, autonomy of the fishing communities fostered by their remoteness and the nested structure of TURFs’ resource management enhanced the resilience of the fishing communities.  相似文献   
63.
胡楚南 《湖南地质》1992,11(4):349-351
湖南的多数矿山,因开采年限较长,资源耗竭而濒于闭坑,部分老矿山将难以维继。为缓解这种严峻局势,延长矿山寿命,本文提出以下对策:①抓紧矿山勘探,摸清矿区资源;②矿、队联合勘查,扩大外围矿量;③加强矿山管理,充分利用资源;④改进选矿工艺,综合回收资源。并据实例阐述了这四点看法。  相似文献   
64.
The high mediolittoral rocky-shore community on the island of Groix (Brittany, France), was studied for the year immediately following the Erika oil spill (12/12/1999). The macrofaunal assemblages of three habitats (exposed bedrock, crevices, boulders) under three situations (non-impacted, impacted and not washed, impacted and washed) were monitored monthly. The assemblage of each habitat showed specific responses to the impacts and initiated various patterns of succession: the bed rock assemblage changed in terms of abundance but no species-richness variations occurred; in the crevices richness variations occurred both in the disappearance of some species and the immigration of opportunistic ones; the boulder assemblage lost many species and remained unstructured one year after the oil spill. These first results of this most recent oil spill in Europe, raised the question of the relative importance of habitat-species and species interactions on the community structure.  相似文献   
65.
Satellite gradiometry using a satellite pair   总被引:1,自引:1,他引:1  
The GRACE mission has substantiated the low–low satellite-to-satellite tracking (LL-SST) concept. The LL-SST configuration can be combined with the previously realized high–low SST concept in the CHAMP mission to provide a much higher accuracy. The line of sight (LOS) acceleration difference between the GRACE satellite pair, the simplest form of the combined observable, is mostly used for mapping the global gravity field of the Earth in terms of spherical harmonic coefficients. As an alternative observable, a linear combination of the gravitational gradient tensor components is proposed. Being a one-point function and having a direct relation with the field geometry (curvature of the field at the point) are two noteworthy achievements of the alternative formulation. In addition, using an observation quantity that is related to the second-instead of the first-order derivatives of the gravitational potential amplifies the high-frequency part of the signal. Since the transition from the first- to the second-order derivatives includes the application of a finite-differences scheme, the high-frequency part of the noise is also amplified. Nevertheless, due to the different spectral behaviour of signal and noise, in the end the second-order approach leads to improved gravitational field resolution. Mathematical formulae for the gradiometry approach, for both linear and higher-degree approximations, are derived. The proposed approach is implemented for recovery of the global gravitational field and the results are compared with those of LOS acceleration differences. Moreover, LOS acceleration difference residuals are calculated, which are at the level of a few tenths of mGal. Error analysis shows that the residuals of the estimated degree variances are less than 10–3. Furthermore, the gravity anomaly residuals are less than 2 mGal for most points on the Earth.  相似文献   
66.
一种基于Web的数字地理信息系统安全解决方案   总被引:1,自引:0,他引:1  
田斌  孙敬杰  杨军 《四川测绘》2007,30(3):141-144
本文提出了一种基于Web的数字地理信息系统安全解决方案,该解决方案采用身份认证技术和传输加密技术确保身份认证和数据传输安全;采用灾难恢复技术最大限度地降低大规模灾难事件的发生带来的损失;采用入侵检测和防火墙技术确保网络存储的安全性;采用文件存储加密保证服务器被攻占后数据不被窃取;数字水印日志系统的实现确保数字地理信息系统日志的权威性、不可否认性以及完整性。  相似文献   
67.
Biomarkers are generally applied to detect pollution in environmental monitoring. Such biological responses should accurately reflect the stress over time in a quantitative manner. As such, the initial and maximum responses induced by stress, as well as adaptation and recovery of these biomarkers, need to be fully understood or else erroneous false-negative or false-positive may be arrived. However, most of the biomarker studies only provided information on initially induced responses under different concentrations of toxicants, while biological adaptation and recovery were poorly known. In this study, the time required for induction, adaptation and recovery of lysosomal integrity in green-lipped mussel Perna viridis upon exposure to benzo[a]pyrene was investigated over a period of 62 days. Maximum induction occurred on day 6 when lysosomal integrity was significantly reduced by 51%, and no further change or adaptation was detected thereafter. When mussels were depurated in clean seawater after 18 days of exposure to benzo[a]pyrene, a gradual recovery was observed, with lysosomal integrity returning to its background level and showing a complete recovery after 20 days of depuration. Lysosomal integrity was significantly correlated with the body burden concentrations of benzo[a]pyrene and condition index of the mussels. The relatively fast induction (6 days) and recovery (20 days) without apparent adaptation suggested that lysosomal integrity in P. viridis can serve as a good biomarker in biomonitoring, as its response is not likely to generate both false-negative and false-positive results.  相似文献   
68.
从地震紧急处置程序、信息报送、灾情调查与烈度评定、震情监视与趋势判定、应急宣传等方面介绍了甘肃省地震局在四川九寨沟7.0级地震发生后的应对过程和工作成效,揭示了甘肃灾区的震害特点并得出了相应的启示,归纳总结了甘肃灾区震后恢复重建的对策措施。  相似文献   
69.
This paper introduces the response process of the Gansu Earthquake Agency during the Jiuzhaigou MS7.0 earthquake in Sichuan Province,including earthquake emergency disposal procedures, information reports, disaster investigation and intensity assessment, seismic monitoring and trend determination, and emergency dissemination.This paper reveals the characteristics of earthquake damage in the quake-hit areas of Gansu Province, draws some corresponding conclusions and summarizes the countermeasures for recovery and reconstruction in the quake-hit areas of Gansu Province.  相似文献   
70.
同位素技术是研究区域地下水循环规律的主要手段之一。本文对平原区地下水进行了取样分析,运用同位素技术并结合水文地质条件,研究了北京市平原区地下水循环演化规律。运用^3H和^14C的测年技术确定了地下水年龄;利用D和18^O关系曲线探讨了地下水的起源;按照是否积极参加了现代水循环的原则将第四系地下水划分为浅层水和深层水;对浅层水和深层水的更新状况进行了研究。研究表明,浅层水广泛分布于北京平原区,径流条件好,更新快;深层水主要分布于永定河、潮白河冲洪积扇下部及冲洪积平原的深部地区,补给条件相对差,与现代大气降水联系弱,径流条件差,更新慢。  相似文献   
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