The Application of Geostatistics to Analysis of Grain Size Trend in the Eastern Beibu Gulf

在北部湾东部海域采集表层沉积物71个,通过粒度分析获得其粒度参数(平均粒径、分选系数、偏态),用克里格插值法将不规则采样站位的粒度参数内插为规则网格分布的相应粒度参数。采用地统计法分析其空间相关性,计算度量空间相关性范围的参数,即半方差图中的变程值。结果表明,使用地统计分析获得的粒度参数变程值物理意义较为明确,可作为粒径趋势分析模型的特征距离,其中分选系数变程值作为特征距离的计算结果与前人的海流、沉积物输运信息更为吻合;这在一定程度上消除了传统方法(试算法或经验估计法)获取特征距离可能造成的模型计算误差。采用不同间距插值时得到的粒径趋势矢量具有不同的空间分辨率,其中高分辨率的细化图所反映的海底沉积物净输运趋势与余流和环流等所反映的沉积物输运细节特征吻合较好,低分辨率的概化图可大致反映该区域沉积物的总体输运趋势。地统计分析的结果对未来研究工作中采样间距的选取也具有指导意义。A total of 71 surficial sediment samples are collected in the eastern Beibu Gulf, and then the moment parameters (i.e. mean size, sorting coefficient and skewness) are obtained by grain size analysis. By using kriging interpolating methods, the regular meshes of grain size parameters are calculated. A geostatistic analysis is applied to study the spatial autocorrelation for these parameters; while the range, a parameter in the semivariogram metering the bound of the spatial autocorrelation, is estimated. It shows that the range for sorting coefficient is physically meaningful, and also the obtained grain size trends are consistent with the annual ocean circulation pattern and sediment transport rates from previous studies. Thus, the range from the sorting coefficient variogram can be used as the characteristic distance in the grain size trend analysis model, which may remove the bias caused by traditional determination of characteristic distance (e.g. based on experience or testing methods). The sediment transport patterns are retrieved on the basis of grain size parameters interpolated with varied distances, which indicates that the small interpolation distance can produce better transport pattern with high resolution and give more detailed information. Hence, the results from geostatistic analysis can be guidable in determination of sampling stations density in the future field work.国家908专项(908-01-ST09);; 国家大学生创新训练计划项目(SIT-05);; 教育部“新世纪优秀人才支持计划”(NCET-06-0446);; 国家基础科学人才培养基金(J0630535)~

Sediment transport patterns in the eastern Beibu Gulf based on grain-size multivariate statistics and provenance analysis

通过对北部湾东部海域表层底质样的粒度和重矿物分析,获得了粒度和矿物组成特征。对粒度进行因子分析获得了4个主控因子,其中因子2和3分别代表细颗粒的悬移质组分和陆源粗颗粒推移质组分,指示来自琼州海峡和北部湾西岸、西北岸的物源贡献,而且因子2的高得分区与弱环流背景相吻合;因子4反映了粤西和海南岛东岸沿岸流的物源贡献。采用重矿物组合,将研究区沉积物的物质来源划为4个分区。分别对4个物源分区使用粒径趋势分析模型,把它们合并后获得了整个研究区的趋势矢量,其中海湾北部沉积物输运汇聚中心的位置与余环流的中心位置基本一致,海南岛西部海域沉积物显示为向北输运的特征,与地貌、水动力特征基本吻合,在一定程度上可消除物源混合造成的影响。在使用粒径趋势分析模型获取沉积物净输运方向时,需要综合考虑物源差异和空间尺度对沉积物粒径趋势的影响。Sediment samples collected from the eastern Beibu Gulf were analyzed in the laboratory to obtain grain-size distributions and mineral components.Four main control factors are obtained using a factor analysis.Factor 1 is contributed by 2.5Φ-3.75Φ and 5.75Φ-7.75Φ.Factor 2 respects fine suspended load component,indicating that the provenance contribution from the Qiongzhou Strait and the high score area is consistent with the weak circulation.Factor 3 is a indicator of terrigenous coarse bedload component from the west and northwest coast of the Beibu Gulf.Factor 4 can reflect the transportation by the coastal current along the east coast off Hainan Island and the west of Guangdong Province.The study area can be separated into four subareas of the sediment sources on the basis of heavy mineral analysis.A grain-size trend analysis model is separately used for the four subareas to estimate the net sediment transport pathways,which can remove the affects induced by the sediment mixing from different sources.A converge center of grain-size trend vectors in the area of the west of Hainan Island might result from the mixing of different sources of sediments,instead of sediment transport.Actually,the northward transport dominates this area of the west of Hainan Island.Another converge center in the northern area is well agreement with the local geomorphology and large-scale ocean circulation pattern.Thus,the application of grain-size trend should consider the effect of sediment sources and spatial scales in order to derive the reasonable net sediment transport pathways.国家和海南省“九2八”专项资助(908-01-ST09;HN908-02-05);国家大学生创新训练计划项目资助(061028405);国家基础科学人才培养基金项目资助(J0630535

Perplexing problems in risk communication of emergent public security events: a psychological perspective

任何突发公共安全事件一定会影响到公众的心理,而公众的心理行为反过来又会对事件的发展演变产生巨大的影响。在危机发生时期,相关政府部门尤其需要了解突发事件中的公众心理,并通过科学地发布风险信息来减轻和化解社会心理压力,同时引导公众正确地认知风险。从风险沟通的角度入手,以问题形式报告了心理学界在风险认知及行为决策方面所积累的研究,希望这些研究成果能够为突发公共安全事件应急方案的制定提供心理学方面的理论依据

突发公共安全事件的风险沟通难题——从心理学角度的观察

任何突发公共安全事件一定会影响到公众的心理,而公众的心理行为反过来又会对事件的发展演变产生巨大的影响。在危机发生时期,相关政府部门尤其需要了解突发事件中的公众心理,并通过科学地发布风险信息来减轻和化解社会心理压力,同时引导公众正确地认知风险。从风险沟通的角度入手,以问题形式报告了心理学界在风险认知及行为决策方面所积累的研究,希望这些研究成果能够为突发公共安全事件应急方案的制定提供心理学方面的理论依据

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies