Multi-decadal shoreline change and beach connectivity in a high-energy sand system     

Brendon Blue  Paul S. Kench 《新西兰海洋与淡水研究杂志》2013,47(3):406-426

ABSTRACT

Understanding how and why the world’s coastlines are changing is a pressing international concern in a context of rising sea levels, increased climatic variability and intensifying coastal development. Medium to long-term records of coastal change are rare worldwide and often limited to individual beach compartments. This study presents a 70-year (1940–2010) aerial imagery record to compare decadal changes in shoreline position across four high-energy west coast beaches near Auckland, New Zealand/Aotearoa: Whatipu, Karekare, Piha and Te Henga (Bethells). The common exposure of these adjacent mesotidal beaches to changing wind and wave conditions might, if they present the dominant controls on shoreline position, be expected to produce synchronous change. Whatipu (935?m), Piha (32?m) and Te Henga (52?m) showed net overall progradation for the study period, while Karekare retreated slightly (?4.1?m). All except Whatipu underwent periods of beachwide erosion. Shoreline change was not coherent between beaches, despite similar exposure to variations in wind, wave and sea level. Variable sediment supply from northward littoral drift is implicated as the primary control on decadal-scale shoreline change for these beaches, highlighting the importance of local context in influencing shoreline response to changing environmental conditions.  相似文献   

渤海湾肠道病毒的季节分布及其污染类型分析   总被引：1，自引：0，他引：1  

明红霞  樊景凤  朱琳 《海洋学报》2013,35(6):162-169

肠道病毒是一类水传播胃肠道疾病的重要病原体。为了解感染性肠道病毒在海水环境中的季节分布规律、污染类型以及与流行病学的关系,于2010年12月到2011年10月应用能够提供病毒感染性信息的细胞培养结合实时定量PCR（ICC-qPCR）方法,分4个季节对渤海湾天津近岸海域表层海水中肠道病毒进行了监测。500 mL海水经超滤浓缩,48 h细胞培养,然后用qPCR检测得到四季海水样品中感染性肠道病毒的浓度为0.2~196 PFU/L,平均值为60 PFU/L,其中夏季和秋季肠道病毒浓度较高,其平均值分别为82 PFU/L和110 PFU/L。秋季阳性检出率最高（85.7%）,其次是冬季（71.4%）。经测序分析,其主要污染类型是脊髓灰质炎 Ⅰ 型疫苗株,此外,还检测出危及公众健康的一株类口服脊灰 Ⅰ 型疫苗脊灰和一株脊灰疫苗衍生株。由此可见,肠道病毒的季节分布和主要污染类型与临床上的流行趋势基本一致,海洋作为一个天然的受纳水体为病毒提供了良好的栖息场所和传播机会,对公众健康存在着潜在的威胁。因此,为减少相关疾病的暴发,应重点加强肠道病毒流行季节的海洋水质监测。  相似文献   

深海腐蚀检测用水密电子舱设计   总被引：1，自引：0，他引：1  

李强  李焰 《海洋科学》2013,37(11):64-68

设计了一种可在300 m 水深条件下进行腐蚀电化学在线检测作业的水密电子舱, 它主要由耐压水密壳体以及集成在壳体外部的插接件式电极系统和多孔屏蔽罩组成。耐压壳体由圆柱形筒体和加强型平盖构成, 满足设计条件下的强度、密封、防腐要求。三电极系统采用水密接插件式设计, 安装在加强型平盖上; 电极系统与外部多孔罩组成开放屏蔽式电解池, 可在水下进行在线电化学测试。  相似文献   

Quantitative Analysis of Meso-β-scale Convective Cells and Anvil Clouds over North China     

LIN Yinjing  WANG Hongqing  HAN Lei  ZHENG Yongguang  WANG Yu 《大气科学进展》2010,27(5):1089-1098

This paper proposes several quantitative characteristics to study convective systems using observations from Doppler weather radars and geostationary satellites. Specifically, in order to measure the convective intensity of each system, a new index, named the ``Convective Intensity Ratio' (CIR), is defined as the ratio between the area of strong radar echoes at the upper level and the size of the convective cell itself. Based on these quantitative characteristics, the evolution of convective cells, surface rainfall intensity, rainfall area and convectively generated anvil clouds can be studied, and the relationships between them can also be analyzed. After testing nine meso-β-scale convective systems over North China during 2006--2007, the results were as follows: (1) the CIR was highly correlated with surface rainfall intensity, and the correlation reached a maximum when the CIR led rainfall intensity by 6--30 mins. The maximum CIR could be at most ～30 mins before the maximum rainfall intensity. (2) Convective systems with larger maximum CIRs usually had colder cloud-tops. (3) The maximum area of anvil cloud appeared 0.5--1.5 h after rainfall intensity began to weaken. The maximum area of anvil cloud and the time lag between maximum rainfall intensity and the maximum area of anvil cloud both increased with the CIR.  相似文献   

A New Mechanism of Convective Cell Regeneration and Development Within a Two-Dimensional Multicell Storm          下载免费PDF全文

BAO Xuwei  TAN Zhemin 《Acta Meteorologica Sinica》2009,23(4):413-427

In this study, based on simulations of a two-dimensional multicell storm under a ground-layer upshear （Uz〈0） by a mesoscale numerical model, a new mechanism of cell regeneration and development within the multicell storm at the ＂less than optimal shear＂ state.is proposed. In the presence of a ground-layer upshear, the circulation associated with the surface cold pool is not counteracted by that associated with the ambient wind sl~ear, and the density current extends out faster, making the multicell storm stay at the ＂less than optimal shear＂ state. As a result, a new cell is triggered by the strong vertical perturbation ahead of the mature convection, rather than by the split-up from the updraft at the leading edge of the surface cold pool as well as the gust front. The latter is the mechanism at the ＂optimal＂ state proposed by Lin et al. in 1998. In the new mechanism, the regenerated cell grows fast with the incident warm moist air from the upstream of the multicell storm, and tends to cut off the moist airflow into the mature convection at its western sector. Consequently, the mature convection would weaken, be replaced, and eventually decay. Actually, these two different mechanisms come into play in a way depending on the relationship between the circulation of the low-level shear and that of the cold pool. When the circulation of the cold pool is stronger than that of the wind shear, the multicell storm is at the ＂less than optimal shear＂ state, and the new convective cell is produced by the disturbance ahead of the mature cell. When the circulation of the cold pool is weaker, the cell regeneration is dominated by the mechanism at the ＂optimal＂ state, and the new cell is split from the gust front updraft. Therefore, these two mechanisms are not contradictive. With a moderate ground-layer upshear, they can alternately operate within a multicell storm.  相似文献   

碳酸盐岩中缝洞方解石成岩环境的矿物地球化学判识——以塔河油田的沙79井和沙85井为例   总被引：1，自引：0，他引：1  

钱一雄  陈强路  陈跃  罗月明 《沉积学报》2009,27(6):1027-1032

摘要在塔里木盆地塔河油田4区沙79井、6区沙85井奥陶系鹰山组岩芯的详细观察基础上,对裂隙、溶洞及巨型洞穴中的方解石晶体的晶胞参数、化学成分、碳、氧同位素、流体包裹体中的氢同位素等分析与研究表明,至少存在两种成岩环境:一是以大气淡水表生环境,方解石中晶胞参数(c)=17.057~17.062,Fe2O3＝0.06%~0.07%,Sr=53.3×10-6~96.2×10-6、Ba=19×10-6~28×10-6,Mg/Ca(×103)＝1.94~5.14,Sr/Ba＝2.12~5.24,δ18OPDB较低（-15‰~-17‰）、较低δ13CPDB（-4‰~-2.0‰）,不含或较少含烃类,流体包裹体中氢δDPDB＝-94.99‰~-109.54‰为特征;另一是地层混合水埋藏环境为主,方解石中晶胞参数(c)=17.064~17.065（个别达17.212）、Fe2O3＝0.06%~0.18%,Sr=111×10-6~208×10-6、Ba=215×10-6~479×10-6,Mg/Ca(×103)＝1.53~1.76,Sr/Ba＝0.49~0.58,方解石δ18OPDB低（-9.6‰~-13.7‰）、流体包裹体中氢δDPDB＝-77.5‰~-88.2‰为特征;另外,在巨型洞穴中方解石中组分的剧烈变化反映了洞穴充填发生于不同的水文地质—地球化学体系。  相似文献   

FATTY ACIDS PROFILE IN A HIGH CELL DENSITY CULTURE OF ARACHIDONIC ACID-RICH PARIETOCHLORIS INCISA （TREBOUXIOPHYCEAE, CHLOROPHYTA） EXPOSED TO HIGH PFD   总被引：1，自引：0，他引：1  

Liu Jian-guo  Zvi Cohen  Amos Richmond 《中国海洋湖沼学报》2002,20(2):149-156

The changes in arachidonic acid (AA) and fatty acids profiles along the growth curve ofParietochloris incisa, a coccoid snow green alga, were studied in a 2.8 cm light-path flat photobiorcactor, exposed to strong photon flux density [PFD, 2400 μEmol/(m²·s)]. Sixteen fatty acids were identified by gas chromatography showing that AA was the dominant fatty acid (33%–41%) followed by linoleic acid (17%–21%). AA content was closely investigated with respect to total fatty acids (TFA), ash free dry weight (AFDW) of cell mass as well as total culture content. These parameters were influenced significantly in a similar manner by culture growth phase, i.e., slightly decreasing in the lag period, gradually increasing in the logarithmic phase, becoming maximal at the early stationary phase, starting to decrease at the late stationary phase, sharply dropping at the decline phase. The increase in AA per culture volume during the logarithmic phase was not only associated with the increase in AFDW but also connected with a corresponding increase in AA/TFA, TFA/AFDW as well as AA/AFDW. The sharp decrease in AA content of the culture during the decline phase was mainly due to the decrease in AA/TFA, TFA/AFDW and AA/AFDW, although AFDW declined only a small extent. Maximal AA concentration, obtained at the early stationary phase, was 900 mg/L culture volume, and the average daily net increase of AA during 9 days logarithmic growth was 1.7 g/(m²·day). Therefore, harvesting prior to the decline phase in a batch culture, or at steady state in continuous culture mode seems best for high AA production. The latter possibility was also further confirmed by continuous culture with 5 gradients of harvesting rate. Contribution No. 4138 from the Institute of Oceanology, Chinese Academy of Sciences. Project 39970575 supported by NSFC and A/2786-2 supported by International Foundation for Sciences (IFS).  相似文献   

Raman spectroscopic study of hydrous <Emphasis Type="Italic">γ</Emphasis>-Mg<Subscript>2</Subscript>SiO<Subscript>4</Subscript> to 56.5 GPa     

A. K. Kleppe  A. P. Jephcoat  J. R. Smyth 《Physics and Chemistry of Minerals》2002,29(7):473-476

 Raman spectra of a single-crystal fragment of hydrous γ-Mg₂SiO₄, synthesized in a multianvil press, have been measured in a diamond-anvil cell with helium as pressure-transmitting medium to 56.5 GPa at room temperature. All five characteristic spinel Raman modes shift continuously up to the highest pressure, showing no evidence for a major change in the crystal structure despite compression well beyond the stability field of ringwoodite in terms of pressure. At pressures above ∼30 GPa a new mode on the low-frequency site of the two silicate-stretching modes is clearly identifiable, indicating a modification in the spinel structure which is reversible on pressure release. The frequency of the new mode (802 cm⁻¹ extrapolated to 1 bar) suggests the presence of Si–O–Si linkages and/or a partial increase in the coordination of Si. Direct determination of the subtle structural change causing the new Raman mode would require high-pressure, single-crystal synchrotron X-ray diffraction experiments. The Raman modes of hydrous and anhydrous Mg-end-member ringwoodite are nearly identical up to 20 GPa, suggesting that protonation has only minor effect on the lattice dynamics over the entire pressure stability range for ringwoodite in the mantle. Received: 7 December 2001 / Accepted: 16 April 2002  相似文献   

湘西沃溪金锑金属钨矿床中石英的矿物学研究   总被引：1，自引：0，他引：1       下载免费PDF全文

邵靖邦  樊江  王濮  翁玲宝  陈代璋 《岩石矿物学杂志》1997,16(1):63-74

通过对矿床中不同世代及不同地质产状石英的颜色，形态，物理性质，化学成分，晶胞参数，结晶度的研究及Ｘ射线分析及红外光谱，电子顺磁共振谱等近代物理分析方法的测试，找出矿化石英与非矿化石英及不同类型矿化石英的标型特征，这些标型特征具有重要的找矿勘探意义。  相似文献   

文蛤外套膜组织与细胞培养   总被引：3，自引：0，他引：3       下载免费PDF全文

陈颉  许璞  沈爱国  万夕和  刘海鸥  沈辉  杨家新 《海洋科学》2007,31(6):60-64

以文蛤(Meretrix meretrix Linnaeus)外套膜为材料,采用改良的M199培养基,在不同温度和盐平衡条件下进行组织与细胞培养。培养结果显示,24 h左右外套膜组织边缘有细胞爬出,48 h后开始形成单层新生细胞,并发展为生长晕,7~10 d细胞基本长满培养瓶底。细胞培养可持续30~35 d。作者还描述了培养过程中出现的3种不同形态特征的细胞,并对37℃培养条件下细胞的生长及分裂特征作了描述与讨论。  相似文献