Dissolved carbon in pore waters from the carbonate barrier reef of Tahiti (French Polynesia) and its basalt basement     

R. Fichez  P. Harris  G. Cauwet  P. Dejardin 《Aquatic Geochemistry》1996,2(3):255-271

This paper deals with dissolved inorganic carbon (DIC) and organic carbon (DOC) in pore waters from a 150 m deep hole drilled through the carbonate barrier reef of Tahiti and its underlying basalt basement. Alkalinity-pH measurements were used to calculate the DIC species concentration, and DOC was analysed according to the high temperature catalytic oxidation technique. Salinity was used as a conservative tracer to help identify water origin and mixing within the hole. Water mixing, calcium carbonate dissolution and mineralization of organic carbon combined to form three distinct groups of pore water. In the deeper basalt layers, pore water with alkalinity of 1.4 meq kg^–1 pH of 7.6 and p(CO₂) of 1.2 mAtm was undersaturated with respect to both aragonite and calcite. In the intermediate carbonate layer, pore water with alkalinity of more than 2.0 meq kg^–1, pH of 7.70 and p(CO₂) of 1.4 mAtm was supersaturated with respect to both aragonite and calcite. The transition zone between those two groups extended between 80 and 100 m depth. The shift from aragonite undersaturation to supersaturation was mainly attributed to the mixing of undersaturated pore waters from the basalt basement with supersaturated pore waters from the overlaying limestone. In the top of the reef, inputs from a brackish water lens further increased p(CO₂) up to 5.6 times the atmospheric P(CO₂).  相似文献   

Inhibition of Fertilization and Larval Metamorphosis of the Coral Acropora millepora (Ehrenberg, 1834) by Petroleum Products     

Andrew P. Negri  Andrew J. Heyward 《Marine pollution bulletin》2000,41(7-12):420-427

Accidental oil spills from ships or rigs and inputs of effluent such as production formation water (PFW) are key perceived threats to tropical biota from industry activities. Scleractinian corals are an important functional component of tropical reefs and the abundance, diversity and resilience of coral communities can be used as an indicator of ecosystem health. In this paper, we report the effects of petroleum products, including water accommodated fractions (WAF) of crude oil, PFW and dispersant (Corexit 9527), on fertilization and larval metamorphosis of the widespread scleractinian coral, Acropora millepora (Ehrenberg, 1834) in laboratory-based assays. At 20% v/v PFW fertilization was inhibited by 25%. This concentration was equivalent 0.0721 mg l⁻¹ total hydrocarbon (THC). In contrast, larval metamorphosis was more sensitive to this effluent, with 98% metamorphosis inhibited at the same concentration. Crude oil WAF did not inhibit fertilization of gametes until dispersant was introduced. Dispersed oil was slightly more toxic to fertilization than dispersant alone, suggesting toxicity to that event may be additive. The minimum concentration of dispersed oil which inhibited fertilization was 0.0325 mg l⁻¹ THC. Larval metamorphosis was more sensitive than fertilization to crude oil. Although crude oil and dispersant inhibited larval metamorphosis individually, this toxicity was magnified when larvae were exposed to combinations of both. Crude oil inhibited metamorphosis at 0.0824 mg l⁻¹ THC and at 0.0325 mg l⁻¹ THC when dispersed in 10% v/v (dispersant/oil). Management of petroleum-related risks to spawning corals should consider not only the occurrence of the annual coral spawning event, but also the subsequent 1–3-week period during which most larval metamorphosis and recruitment occur.  相似文献   

Mass Diving Tourism – A New Dimension Calls for New Management Approaches     

Peter van Treeck  Helmut Schuhmacher 《Marine pollution bulletin》1999,37(8-12):499-504

Diving has become a booming branch of the tourism business. The economies of many countries with reef-lined coasts depend on high numbers of tourist divers; the resultant degradation of reefs by mechanical damage is accepted due to the short-term gain from the tourism business. Many activities of recreational diving do not particularly require coral reefs – any varied three-dimensional structure (e.g. a wreck) may be sufficiently attractive. The conflict between the needs of nature conservation and the economic interests of diving tourism can be mitigated by the formation of artificial underwater attractions as reef substitutes. Based on experiments in the northern Red Sea, we propose to deposit calcium minerals from the seawater in situ by electrolysis on a template of any desired shape. After transplantation of living coral fragments, a diverse community will develop. With this method different modules can be designed and formed on the seabed which can serve different needs such as diver training, environmental education and recreation as well as reef rehabilitation. By a combination of such modules, a recreational underwater park can be formed well suited to function as a DAD (diver aggregation device) and therefore, divert diver pressure from the natural reef.  相似文献   

Preparation of a New Geological Survey of Japan Geochemical Reference Material: Coral JCp-1   总被引：2，自引：0，他引：2  

Takashi Okai  Atsushi Suzuki  Hodaka Kawahata  Shigeru Terashima  Noboru Imai 《Geostandards and Geoanalytical Research》2002,26(1):95-99

A new geochemical reference material, coral Porites sp. JCp-1 has been prepared by the Geological Survey of Japan (GSJ). Provisional values for twenty one major, minor and trace elements are presented. The homogeneity tests showed that all elements studied are considered to be homogeneously distributed.  相似文献   

华宁盘溪金山-大石山泥盆纪珊瑚礁的基本特征     

洪天求  戴清明 《吉林大学学报(地球科学版)》1997,(1)

滇东华宁盘溪火车站以北的金山—大石山地区发育中、晚泥盆世的丘状珊瑚礁。以Ａｌｖｅｏｌｉｔｅｓ和Ｔｈａｍｎｏｐｏｒａ为代表的床板珊瑚为造礁生物。纵剖面上岩相变化的记录清楚地表明，该礁体经历了定殖、繁殖和衰亡三个阶段。海水变浅及其盐化是导致礁体衰亡的直接原因  相似文献   

湖南慈利晚二叠世海绵礁与珊瑚礁的古生态研究   总被引：5，自引：0，他引：5       下载免费PDF全文

王永标  徐桂荣 《地球科学》1997,22(2):135-138

中国南方晚二叠世生物礁分布广泛，但绝大多数属于海绵礁，湖南慈利晚二叠世除发育有海绵礁外，还有至今为止发现的世界上发育最好的古代珊瑚礁，而且海绵礁与珊瑚礁在同一条带上连续分布；因此是研究海绵礁与珊瑚礁古生态关系十分理想的场所，通过对慈利晚二叠世海绵礁及珊瑚礁内部造礁生物群落、沉积相特征，礁化演化序列及成岩作用特征等的分析和对比来研究它们之间的生态关系，发现其中的海绵礁为台地边缘礁，而珊瑚礁则应属于岸  相似文献   

Depth–transport functions and erosion–deposition diagrams as indicators of slope inclination and time-averaged traction forces: applications in tropical reef environments     

Johann Hohenegger  & Elza Yordanova 《Sedimentology》2001,48(5):1025-1046

The trigonometric relationship between slope inclination, the horizontally acting time‐averaged traction force and the vertical depth of transport allows the estimation of one factor, when both others are known. Depth–transport functions can be deduced by comparing the depth distributions of living organisms and their skeletal remains, and this paper simplifies this comparison using foraminifera in which a single test represents an individual. Differences in distribution parameters between living individuals and empty tests allow depth–transport functions to be determined; these functions differ between species at a single transect according to the varying buoyancies of the tests. Within a single species, differences in depth–transport functions between locations are based on either slope inclination or traction intensities. After establishing a mean depth–transport function by averaging species‐characteristic functions, the time‐averaged traction force acting on the studied transect can be calculated. Transport intensities are also estimated using an erosion–deposition diagram that combines the relative frequency distributions of living individuals and empty tests. The proportion of ‘eroded’, ‘parautochthonous’ and ‘allochthonous’ tests mirrors the influence of both slope inclination and traction force for the deposition of empty tests. To test the model, six species of symbiont‐bearing benthic foraminifers were investigated at two transects in front of a NW Pacific coral reef. One transect is distinguished by a strong slope flattening below the steep reef slope (30 m), whereas further steepening characterizes the equivalent part in the other transect. These differences are mirrored in the depth–transport functions as well as in the erosion–deposition diagrams of all species. The time‐averaged traction forces differ in intensities between transects, because of the position of the reef front with respect to the predominant wind direction. However, the form of the functions is identical and distinguished by an increase from the surface to 35 m depth, followed by a decrease down to 105 m. This can be explained by successive onshore and offshore forces acting on the shallow slope, such as the tropical cyclones that cross the region every summer.  相似文献   

中国早石炭世四射珊瑚动物地理分区   总被引：1，自引：0，他引：1       下载免费PDF全文

江茂生  何心一 《地质科学》1994,(3):228

 以中国主要地区早石炭世四射珊瑚化石资料为依据,采用传统的综合比较法与二态聚类分析方法相结合,把中国早石炭世四射珊瑚归为两大动物地理区,即特提斯大区和岗瓦纳大区,其中特提斯大区东部中国部分可再分为四个亚区:(1)华南亚区;(2)滇西亚区;(3)西南亚区;(5)北方亚区。  相似文献   

藏北申扎地区上二叠统木纠错组的建立及皱纹珊瑚组合   总被引：5，自引：6，他引：5  

程立人  王天武等 《地质通报》2002,21(3):140-143

在申扎县城东南木纠错南东岸附近发现一套巨厚的以白云岩、白云质灰岩为主组成的岩系,厚达2348m。该岩系整合覆于下二叠统下拉组之上,并于其底部发现中国南方晚二叠世早期珊瑚动物群中的重要分子WaagenophyllumindicumcrassiseptatumWu和LiangshanophyllumstreptoseptatumWang两种,与其共生的还有Lobatophyllumzakan-genseWu和WaagenophyllummegacolumetumWu,它们共同组成一个晚二叠世早期特有的皱纹珊瑚动物组合,命名为Waagenophyllum-Liangshanophyllum-Lobatophyllum组合。将含有这一珊瑚化石组合的以白云岩、白云质灰岩为主的岩系另建立新组———木纠错组,该组在层位上相当于中国南方上二叠统的吴家坪组。  相似文献   

南沙群岛景观及区域古地理   总被引：6，自引：1，他引：6  

赵焕庭  袁家义 《地理学报》1995,50(2):107-117

本文论述了南沙群岛的海底地形、海底表层沉积、珊瑚礁景观、区域新生代古地理、以永暑礁为代表的古气候与古海面，以及本区古海洋等自然地理特征。  相似文献