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81.
The article takes as its point of departure the apparently contradictory findings in recent research about accident rates in shipping and IMO implementation records. It is argued here that although IMO conventions have probably greatly improved shipping safety, they cannot credibly be held to be the chief cause of reduced accident rates as claimed in a recent Marine Policy article, when the documented failures of flag state and port state implementation continue to leave vessels sailing with grave deficiencies. The present analysis posits and corroborates a cluster of linked tendencies that jointly undermine IMO implementation. The core problem is IMO’s weak connection to the national maritime administrations, leading to broadly discretionary practices, exacerbated by language difficulties. Adding new rules is no panacea, as new rules in some cases negatively affect the functioning of existing regulations, and sometimes seem motivated mainly to show political alertness. The structural weakness of the IMO/member state link is the core implementation problem that urgently needs to be dealt with if marine safety is to be improved. The concluding section proposes a reform to bring the IMO out of this conundrum and ensure effective implementation. 相似文献
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Monitoring surveys are an important tool for detecting new arrivals of exotic species, for documenting patterns of invasion, and exotic species impacts. Faced with time and cost constraints, these surveys are increasingly focused on lists of target pest species, identified as being most likely to arrive and cause significant harm. We used the national survey of Australian international ports for introduced marine pests as a case study to assess: (1) the taxonomic rigor of surveys focused on detection of target species; and (2) how the ability of port surveys to inform invasion patterns is dependent on taxonomic approach. Our analysis of the 46 available reports revealed common sub-optimal taxonomic practices that compromised their utility to identify abiotic conditions that are good predictors of biological invasion. Thus, although surveys for target species may provide information on the distribution of a handful of species, they may fail to do much else. 相似文献
86.
根据海岸河口地区潮流、波浪、泥沙的运动特点及其相互作用机制,考虑了波浪场产生的"波浪辐射应力"和"波流挟沙力"动力要素对潮流场和泥沙运动的影响,在泥沙扩散方程中考虑了紊动水流作用,采用有限元加权集中质量法,建立了考虑波浪作用的潮流泥沙数学模型,并利用锦州港港区的潮流及泥沙资料对模型进行了验证。验证结果表明,潮位吻合良好,流速、流向、含沙量分布基本相似。在此基础上,模拟了工程建设前后,港区附近潮流场和泥沙淤积的变化,分析了泥沙骤淤现象。模拟结果表明,该数学模型能够适用于海岸河口地区潮流、泥沙的模拟,为波浪作用下潮流场和泥沙淤积的预测提供一种新的模拟方法,具有良好的应用前景。 相似文献
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本文研究了由2020年12月29日至31日强冷锋引起的影响洋山港海域的温带风暴潮过程。通过气象观测数据分析了其天气过程, 并利用FVCOM-SWAVE波浪-风暴潮耦合模式对该过程进行了高分辨率的数值模拟, 同时结合潮位站及浮标站观测数据对模拟结果进行了验证, 分析模拟了波浪、潮流、风暴增减水特征。结果发现, 该次冷锋型温带风暴潮过程主要表现为先短时风暴增水后出现长时间风暴减水的特征, 最大风暴减水可达65~70cm, 其主要诱因包括研究海域气压的快速升高并维持、长时间持续的偏北大风及波流相互作用。相关敏感试验研究了3种因子对风暴增减水位的贡献大小, 发现风暴增水峰值期间风场贡献占比约为90%, 海平面气压场约为5%; 风暴减水峰值期间, 海平面气压场的贡献度约占55%, 风场约占40%, 而波浪的贡献均不足10%。洋山港航道内风暴期间潮流流速最大可达到2.6~2.8m•s-1, 落潮时为东南向离岸潮流, 涨潮时为西至西北方向的外海潮波传入潮流; 洋山港航道潮流始终是东南或西北向, 此处流速辐合, 是洋山海域流速最高的区域。 相似文献
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利用1976—2021年共6期遥感影像获取了海口市东寨港红树林自然保护区范围内不同年代的湿地数据,基于转移矩阵、问卷调查和主成分分析,剖析了45年来保护区红树林的变化及其与周边社区的关系。结果显示:1)保护区内红树林面积由1976年的1 395.84 hm2增至2021年的1 589.28 hm2,期间呈“骤减缓升”之势。除1976—1985年红树林面积有减少外(减少了250 hm2,减少幅度为18%),其余时段红树林面积均为增长态势。2) 1976—2021年保护区红树林转出对象分别是淤泥质海滩(34.32 hm2)、河流(25.81 hm2)、海水养殖场(21.06 hm2)、其他用地(10.58 hm2)和洪泛湿地/内陆滩涂(8.26 hm2);转入为红树林的对象主要是淤泥质海滩(177.41 hm2)、河流(38.18 hm2)、其他用地(28.21 hm 相似文献
89.
提升金融服务实体经济效率是海南自贸港建设亟待研究和突破的“靶点”。论文通过测算2011—2020年海南自贸港18市县金融服务实体经济效率,利用Dagum基尼系数与Kernel密度估计方法刻画效率的时空异质性,并借助随机森林模型揭示其驱动机理,创新性地从时空视角挖掘海南自贸港金融服务实体经济效率分异机制。研究发现:(1)海南自贸港金融服务实体经济效率时空非平衡性明显,时序上阶段性显著,空间上呈西高东低、高值聚集、中部“洼地”的分布特征,西北部市县与中部市县各自逐步形成高值、低值聚集区;(2)总体及沿海市县梯度分化特征逐步加强,而非沿海市县内部差距则逐步缩小,沿海区域金融服务实体经济效率的空间分异是总体分异的主要来源;(3)政府干预是效率分化的主导因素,含金融集聚度在内的影响因素对效率均呈非线性影响且作用趋势与阈值各异,各因素的边际产出能力及各市县对要素的吸收与应用能力的动态差异是时空异质性的主要来源。研究结论可为优化海南自贸港金融资源的空间配置、提升金融服务实体经济效率提供科学依据。 相似文献
90.
This study presents the stratigraphic and floristic interpretations of data collected from a 6.49 m core taken within the Rowley River Marsh, Massachusetts. Twenty-five samples were collected at 28 centimeter intervals from the core in this Holocene coastal marsh. Based on stratigraphic control, the age of the core samples includes a time sequence extending back 4,600 years from the present. Analysis of the core stratigraphic units suggests the environment has essentially been a low energy estuarine system for the past 4,600 years. The 25 samples were also processed for pollen taxa present since 4,600 years B.P. A discriminant function analysis was used to test the floristic zonal similarity of the diagnostic taxa (Picea, Pinus, Carya, Tsuga, Quercus) from the core with those same taxa used to establish the floristic zones for the southern New England region. The results of the analysis demonstrated that 84% of the samples were correctly classified by floristic zone. Although the distribution of diagnostic taxa from this study is generally in agreement with the previously established floristic zones, the Tsuga taxa are present throughout the temporal sequence, suggesting the occurrence of a cooler climate regime for the sampling site since 4,600 years B.P. 相似文献