Biokarst on Limestone Coasts, Morphogenesis and Sediment Production   总被引：3，自引：0，他引：3  

Jürgen  Schneider Horst  Torunski 《Marine Ecology》1983,4(1):45-63

Abstract. Biokarst-forms on limestone coasts are developed and arranged according to the bionomic zonation. The development of biokarst is the result of bioerosion, a synergistic effect of biological corrosion by endoliths and biological abrasion by grazers.
The cumulative effect of biogenic carbonate destruction leads to coastal destruction with a resulting highly profiled morphology on the limestone surfaces along the coastal profile. Under the influence of environmental factors a zonation of organisms develops which brings in turn a zonation of erosion rates (0.1-1.1 mm a^-1) resulting in biokarst-forms such as rock holes, rock pools and notches.
Products of bioerosion on limestone coasts are dissolved carbonate (by biological corrosion, 10–30% of the decomposed limestone) and particulate carbonate (by biological abrasion, 70–90% of the decomposed limestone) both of which contribute directly or indirectly to nearshore sedimentation. Size and shape of the bioerosional grains are determined by the boring pattern of the endoliths. The fine-grained sediments (maximum within the fraction 20–63 μm) contribute 3–25 % to the nearshore sediments.
Drastic changes in the biological zonation (like the mass invasion of the sea urchin Paracentrotus lividus in the Northern Adriatic since 1972 which eliminated nearly the entire macrophyte zone) due to unknown factors or pollution can have a profound effect on the bioerosion rates, altering them by as much as a factor of ten.  相似文献   

Correspondence between the distribution of hydrodynamic time parameters and the distribution of biological and chemical variables in a semi-enclosed coral reef lagoon     

Jean-Pascal Torrton  Emma Rochelle-Newall  Aymeric Jouon  Vincent Faure  Sverine Jacquet  Pascal Douillet 《Estuarine, Coastal and Shelf Science》2007,74(4):766

Hydrodynamic modeling can be used to spatially characterize water renewal rates in coastal ecosystems. Using a hydrodynamic model implemented over the semi-enclosed Southwest coral lagoon of New Caledonia, a recent study computed the flushing lag as the minimum time required for a particle coming from outside the lagoon (open ocean) to reach a specific station [Jouon, A., Douillet, P., Ouillon, S., Fraunié, P., 2006. Calculations of hydrodynamic time parameters in a semi-opened coastal zone using a 3D hydrodynamic model. Continental Shelf Research 26, 1395–1415]. Local e-flushing time was calculated as the time requested to reach a local grid mesh concentration of 1/e from the precedent step. Here we present an attempt to connect physical forcing to biogeochemical functioning of this coastal ecosystem. An array of stations, located in the lagoonal channel as well as in several bays under anthropogenic influence, was sampled during three cruises. We then tested the statistical relationships between the distribution of flushing indices and those of biological and chemical variables. Among the variables tested, silicate, chlorophyll a and bacterial biomass production present the highest correlations with flushing indices. Correlations are higher with local e-flushing times than with flushing lags or the sum of these two indices. In the bays, these variables often deviate from the relationships determined in the main lagoon channel. In the three bays receiving significant riverine inputs, silicate is well above the regression line, whereas data from the bay receiving almost insignificant freshwater inputs generally fit the lagoon channel regressions. Moreover, in the three bays receiving important urban and industrial effluents, chlorophyll a and bacterial production of biomass generally display values exceeding the lagoon channel regression trends whereas in the bay under moderate anthropogenic influence values follow the regressions obtained in the lagoon channel. The South West lagoon of New Caledonia can hence be viewed as a coastal mesotrophic ecosystem that is flushed by oligotrophic oceanic waters which subsequently replace the lagoonal waters with water considerably impoverished in resources for microbial growth. This flushing was high enough during the periods of study to influence the distribution of phytoplankton biomass, bacterial production of biomass and silicate concentrations in the lagoon channel as well as in some of the bay areas.  相似文献   

台湾海峡中、北部上升流区浮游有孔虫的生态研究     

方惠瑛 《热带海洋学报》1995,(3)

分析１９８７—１９８８年在台湾海峡中、北部用浮游生物网采集的水层中的浮游有孔虫标本，研究调查海区浮游有孔虫的生态分布特征及其与海水温度和盐度的关系。结果表明：该海区浮游有孔虫计有１６种，以泡抱球虫Ｇｌｏｂｉｇｅｒｉｎａｂｕｌｌｏｉｄｅｓ为主要优势种类，其次是袋拟抱球虫Ｇｌｏｂｉｇｅｒｉｎｏｉｄｅｓｓａｃｃｕｌｉｆｅｒ和红拟抱球虫Ｇ．ｒｕｂｅｒ。在夏季的７月和８月（特别是７月），浮游有孔虫密集在福建中部沿岸的南日岛至闽江口外海海域一带沿岸水域，其中９０％以上的个体由泡抱球虫组成。此现象推测与夏季出现在福建沿岸的上升流活动有关。  相似文献   

The recreational fishery off Majorca Island (western Mediterranean): some implications for coastal resource management   总被引：3，自引：0，他引：3  

Morales-Nin  Beatriz; Moranta  Joan; Garcia  Cristina; Tugores  Maria Pilar; Grau  Antoni Maria; Riera  Francisco; Cerda  Margalida 《ICES Journal of Marine Science》2005,62(4):727-739

  相似文献   

东海沿岸海区垂直环流及其温盐结构动力过程研究Ⅱ．温盐结构   总被引：2，自引：0，他引：2  

刘兴泉  侯一筠  尹宝树 《海洋与湖沼》2004,35(6):497-506

对于本研究采用的动力学模型及其垂直环流的模拟结果已在第Ⅰ部分论述。作者将对与垂直环流对应的温、盐结构进行分析。温度和盐度模拟结果表明：冬季东海沿岸海区的温、盐分布均为近岸低、外海高;近岸温、盐呈垂直均匀分布,在外海出现分层,其温度为表层高、底层低,而盐度却为表层和底层高,中层偏低,长江口以南的近表层以下形成自近岸伸向外海的弱低盐水舌;长江冲淡水区及长江口以北和其以南外海的近表层有温、盐跃层生成,深底层温、盐呈均匀分布,且保持低温高盐特征;随着海区自北往南纬度的降低,岸坡和水深的增大及沿岸下降流的增强,温度和盐度自近岸至外海的垂直均匀分布跨度逐渐变窄;外海近表层的温、盐跃层强度自北至长江口逐渐增强,而自长江口至南逐渐减弱,其位置自北往南逐渐上移;冬季沿岸下降流使长江冲淡水区的盐跃层变厚。夏季海区的温度分布为近岸和外海高,近岸稍远出现冷水涌升,垂向上呈现显著分层,盐度分布为近岸低、外海高;长江冲淡水区及杭州湾以南外海的次表层存在温、盐跃层,其跃层以上出现混合层,且保持高温低盐特征,跃层以下温、盐大致呈均匀分布,并保持低温高盐特征;随着海区自南往北纬度的增高、岸坡和水深的减小及沿岸上升流自南至长江口和自长江口至北的增强和继而减弱,长江冲淡水区的温、盐跃层强度自南至长江口逐渐增强,而自长江口至北逐渐减弱,外海次表层的温、盐跃层强度却自南至长江口逐渐减弱,自长江口至北又逐渐增强,其温、盐跃层的位置自南往北逐渐上移;夏季沿岸上升流使长江冲淡水区的盐跃层变薄。  相似文献   

杰氏风暴潮预报方法在珠海及粤西海域的应用     

魏晓宇  窦金来  黄根华  周求赞  陈强  王欣睿 《台湾海峡》2007,26(2):197-203

本文通过杰氏风暴潮预报方法对历史上给珠海和粤西海域造成较大影响的台风增水事件进行后报试验,并通过统计分析方法对原有的预报公式进行订正,总结出适合珠海及粤西海域的风暴潮预报公式.利用5a的时间对珠海及粤西海域的台风增水进行试报,结果表明预报准确率分别达95.0%和87.6%,尤其对一些增水较大、影响较严重的台风增水预报相对更加准确,预报准确率均达90.0%以上.这说明订正后的公式对珠海及粤西海域的风暴潮预报能得到较好的预报效果.  相似文献   

海底泉对在海底有限延伸的越流含水层系统中地下水潮汐效应的增强作用     

杨颖  李海龙  夏玉强  孙萍萍 《地下水》2008,30(2):9-14

海底泉在滨海地下水排泄过程中起着重要的作用。本文给出了含有一个海底泉的在海底延伸的越流承压含水层系统中地下水水头在海潮作用下波动的近似解析解。该含水层顶底板隔水且向海底延伸有限距离。假设含水层的海底露头被一层隔水层覆盖,海底泉由一个渗透性很好的完全穿透海底含水层硕板的圆柱体渗漏天窗（海底泉孔）来表示。近似解析解中包含了6个参数：承压含水层的海潮传播参数,海底泉孔中心到海岸线的距离,表示泉的圆柱体的等效半径,海底泉孔中心到含水层海底露头处的距离,承压含水层的海潮载荷效率和弱透水层的越流。分析表明,如果海底泉孔中心到海岸线的距离远大于泉孔的等效半径,且海底泉孔中心到含水层海底露头处的距离远大于泉孔的等效半径时,解析解的近似误差可以忽略。然后本文讨论了解析解的两个基本性质,分析了海底泉对海底地下水水头波动的影响。  相似文献   

杭州湾岸线变迁与城市规划建设     

顾明光  龚日祥  卢成忠  秦祥熙  陈忠大 《上海国土资源》2008,(4):24-29

本文较系统地阐述了杭州湾沿岸平原第四纪地质与地貌特征,扼要分析了钱塘江与杭州湾岸线的变迁历史及其演变趋势。在此基础上,指出海平面持续上升带采的一系列环境问题是未来杭州湾海岸带面临的主要威胁,并对环杭州湾城市化发展规划提出了若干建议。  相似文献   

ANALYSIS OF A CASE OF EAST ASIA COASTAL CYCLOGENESIS^*          下载免费PDF全文

Chen Shoujun  Guo Ying-Hw  Bai Lesheng 《Acta Meteorologica Sinica》1993,7(4):385-411

The evolution of an explosive cyclone off the East Asia coast in March 1979 is described.A shortwave trough in the southern branch of upper-level westerlies initiated the incipient cyclone.Later,a polar trough in the north amplified and became in phase with the southern shortwave to form a major trough.This major trough was responsible for the rapid intensification of the surface cyclone.In the early development stage,warm and moist air was transported northward to the developing area by a strong low-level jet.The ageostrophic wind associated with the low-level jet contributed to the frontogenesis,creating a favorable low-level environment for the rapid deepening.A low-level positive potential vorticity anomaly was created prior to the onset of rapid deepening.It was a result of frontal cloud condensation.The cyclone intensified rapidly when stratospheric air with high potential vorticity penetrated to the mid-troposphere.The rapid deepening took place at a location under the left-exit region of an amplifying jet streak behind the major trough and the right-entrance region of another anticyclonically-curved subtropical jet streak in a quasi-stationary ridge overJapan.Due to the blocking effect of the Tibetan Plateau,two shortwave disturbances were observed in the upper-level westerlies on the north and south sides of the Plateau.The southern disturbance initiated the incipient surface cyclone,while the amplifying northern disturbance was responsible for the rapid deepening.Thus,the evolution of the explosive cyclone in this case can be regarded as consecutive Petterssen's "type-B" cyclogenesis in two separate stages.  相似文献   

Environmental geology problems in the Tyrrhenian coastal area of Santa Marinella, province of Rome, central Italy   总被引：1，自引：0，他引：1  

U. Chiocchini  G. Gisotti  A. Macioce  F. Manna  A. Bolasco  C. Lucarini  G. M. Patrizi 《Environmental Geology》1997,32(1):1-8

 The Tyrrhenian resort of S. Marinella (central Italy) is subjected to significant anthropogenic pressures during the summer vacation period, a common situation all along the Italian coast. Located 65 km NW of Rome on the southern slopes of the Tolfa Mountains, S. Marinella is built on a gently sloping, E–W trending belt which is cut by 14 N–S oriented ephemeral streams that discharge into the Tyrrhenian Sea. The low to medium permeability turbiditic sandstones which outcrop along this belt belong to the Late Cretaceous Pietraforte unit. Three environmental problems are addressed in this study. The first problem is related to the high water supply demand during the summer months which has forced local residents to dig a large number of wells. Extensive pumping from these wells has caused salt-water intrusion into the Pietraforte, thus compromising the domestic use of the groundwater. The second problem consists of the illegal dumping of urban solid waste, material that represents a hazard during significant rain events as well as a possible cause of groundwater contamination. The final issue addressed concerns the flooding potential of the 14 ephemeral streams that cross the inhabited area of S. Marinella, a risk which is highlighted by the disastrous flood which occurred on 2 October 1981 and during the period of the Roman Emperor Settimio Severo (205 A.D.). Some suggestions are proposed to mitigate and contain the effects of these problems. Received: 7 November 1995 / Accepted: 5 December 1996  相似文献