Bacterial iron oxide reduction in a terrigenous sediment-impacted tropical shallow marine carbonate system, north Jamaica   总被引：1，自引：0，他引：1  

Kevin G. Taylor  Christopher T. Perry  Anthony M. Greenaway  Philip G. Machent 《Marine Chemistry》2007,107(4):449-463

Discovery Bay, a carbonate-dominated embayment in north Jamaica, has been subject to inputs for 40 years of iron-rich bauxite sediment associated with the local mining and transport of processed bauxite. As such, this site is an ideal natural laboratory to study the records and impacts of iron oxide inputs upon geochemical, diagenetic, and microbial processes in tropical carbonate sediments.Total Fe contents in sites in the bay not receiving bauxite inputs are negligible and porewater Ca²⁺, SO₄²⁻ and Cl⁻ indicate that bacterial sulphate reduction is an important process. In contrast, surface sediments receiving bauxite inputs contain significant total Fe, from 44 μmol/g in shallow (5 m water depth) sites to 110 μmol/g in deeper (20 m water depth) sites. Up-core increases in total Fe record increased temporal inputs into the bay. Within these Fe-rich sediments porewater data shows the presence of Fe^II released by bacterial Fe^III reduction. There is no direct evidence for significant bacterial sulphate reduction in these sediments. Iron oxides within all bauxite-impacted sediments display a high potential reducibility, from 40% to 80% of the total Fe present as dithionite-extractable Fe^III. Experimental analysis of the potential susceptibility to, and rates of, bacterial Fe^III reduction, utilising Discovery Bay sediment and Shewanella putrefaciens CN32 (a known Fe^III-reducer) has confirmed the high bacterial reducibility of iron oxides within the sediment. Up to 75% of initial dithionite-extractable Fe^III in the sediments was reduced over 15 days.The presence of iron oxides within the Discovery Bay shallow marine carbonate systems has markedly altered the chemical diagenetic processes taking place, with a shift from apparent dominance of bacterial sulphate reduction at non-impacted (Fe-poor) sites, to highly significant bacterial Fe^III reduction in Fe-rich bauxite-impacted sediments. Given the perceived global increases in terrigenoclastic sediment inputs into tropical carbonate systems as a result of land-use and climate changes, coupled with the documented role that iron oxide reduction plays in nutrient and contaminant cycling in sediment systems, more research into the perturbation of early diagenesis by iron oxide inputs is required.  相似文献   

Sensitivity of extreme hydroelastic load effects to changes in ship hull stiffness and structural damping     

MingKang Wu  Torgeir Moan 《Ocean Engineering》2007,34(11-12):1745-1756

A new hybrid method for the time-domain nonlinear simulation of the hydroelastic load effects and the peak over threshold (POT) method for the calculation of the short-term extreme responses are briefly described and applied to a flexible SL-7 class containership and a flexible liquefied natural gas (LNG) ship. Three stiffness levels, three stiffness distributions and three modal damping ratios are used to study the influence of the hull flexibility and structural damping on the short-term prediction of extreme vertical hydroelastic load effects. The results give justification for some simplified treatment of the first vertical flexible mode in early design stage when structural details are not available.  相似文献   

The bottom line: An investigation of the economic,cultural and social costs of high seas industrial longline fishing in the Pacific and the benefits of conservation     

Robert Ovetz 《Marine Policy》2007

High sea industrial longline fishing can be understood as a case study of the cultural, economic, environmental and social impacts of unsustainable fishing technology. While much attention has been attributed to the impact of industrial longlines on the marine ecosystem, little is known about the impact of longline fishing on local food security, employment, cultural belief systems and traditions, revenue generation from marine tourism and climate change. New data demonstrate that the contributions of Marine Protected Areas, marine tourism and recreational fishing to local coastal economies dwarf the contributions of longline fishing. When combined with the impact of overfishing on coastal fishing communities and fish consumers, policies promoting sustainable fisheries must be expanded to take these other factors into account along with issues of biodiversity.  相似文献   

海洋生物提取物“KEMH”研究Ⅱ．对实验动物免疫功能的影响     

林华英  苏冬梅  刘晓范  徐夷凝 《中国海洋大学学报(自然科学版)》1996,(4)

报导“ＫＥＭＨ”对昆明种小鼠免疫功能的影响。结果表明：不同剂量的“ＫＥＭＨ”（１００ｍ／ｋｇ、５０ｍｇ／ｋｇ、２５ｍｇ／ｋｇ）试验组与环磷酰胺（５０ｍｇ／ｋｇ）对照组比较，不论在非特异性免疫或特异性免疫功能方面，经Ｔ检验所得Ｐ值都显示出明显差异：与正常对照组比较则仅限高剂量组（ＫＥＭＨ１００ｍｇ／ｋｇ）显示高度明显差异，中剂量组（ＫＥＭＨ５０ｍｇ／ｋｇ）略显差异或不显差异，小剂量组（ＫＥＭＨ２５ｍｇ／ｋｇ）基本无差异  相似文献   

我国海洋经济展望与推进对策探讨   总被引：1，自引：0，他引：1       下载免费PDF全文

韩忠南 《海洋开发与管理》1995,12(1):12-15

本文就我国海洋经济的发展前景和推进对策进行了初步探讨，提出加强宣传教育、健全法规、加强管理、统一规划、海陆一体开发、以市场为导向、重视生态平衡和环境保护、加强基础设施和安全保障建设、实行政策优惠和多渠道融资、坚持对外开放的增进国际合作等对策建议。  相似文献   

海上地震勘探主要采集参数的选取与验证——以南海北部某调查区为例   总被引：2，自引：1，他引：2       下载免费PDF全文

罗文造  韦成龙  王立明  杨蜀冀 《热带海洋学报》2009,28(4):93-101

采集参数选取的优劣直接关系到野外地震资料质量的高低。作者经过多年海上地震调查实践,总结了一套实用的采集参数选取原则与验证流程。首先结合南海北部某调查区以往的地震和地质资料分析,建立了典型的地震地质结构模型;根据现有调查设备的性能,利用专业软件Nucleus6.2模拟对采集参数选取的理论计算,比较不同采集参数组合的模拟结果,选择有利于调查任务的参数组合。对海上生产前模拟选用的采集参数组合做试验和验证,确定了最适合的参数作业。运用该套原则和流程精心设计,实验获得了高质量野外资料。  相似文献   

港养黄鳍鲷性腺发育和性转变研究   总被引：4，自引：2，他引：4  

洪万树  黄振池 《台湾海峡》1991,10(3):221-228,T002

本文利用光镜和电镜显微技术研究了福建东山县西埔湾黄鳍鲷性腺发育过程和性转变规律。结果表明,港养黄鳍鲷雌性性腺不能向产卵状态过渡,因而不能自然产卵,其卵细胞发育可分为5个时相,卵巢发育也可相应地分为5期。雄性性腺在港养条件下能够发育成熟,其精巢发育可分为6期。Ⅰ龄组雄性个体和雌雄同体并存;Ⅱ龄组大多数个体为雌雄同体,少数个体已转变为雌性鱼;Ⅲ龄组和Ⅳ龄组的个体均为雌性鱼。本文还对卵黄的形成、卵母细胞的退化吸收以及排卵的机制等问题进行了讨论。  相似文献   

黄海大海洋生态系监测和保护数据资料库     

刘亚伟  潘增弟 《海洋科学进展》1993,(3)

本文提出了黄海大海洋生态监测和保护数据和资料库管理系统建设的一种设想计划,着重叙述了建立黄海大海洋生态系数据资料管理系统的框架、功能及其应用。  相似文献   

隐虾类与海洋无脊椎动物的共栖关系(I)          下载免费PDF全文

李新正 《海洋科学》1993,17(6):43-48

研究论述了隐虾亚科这一珊瑚礁环境中引人注目的甲壳动物类群与软体动物、海鞘动物、棘皮动物、腔肠动物和海绵动物等海洋无脊椎动物类群之间的共栖关系,并得出此亚科种类的共栖宿主以腔肠动物最多,其余以次为棘皮动物、海绵动物、双壳类软体动物和海鞘类被囊动物,以及每一种隐虾多以某一目的动物为宿主,宿主跨目者很少,跨纲者更少的结论。为该亚科的分类和进化以及珊瑚礁生态学研究提供了重要基础资料。  相似文献   

Marine Mangrove Fungi   总被引：5，自引：0，他引：5  

K. D. Hyde  E. B. G. Jones 《Marine Ecology》1988,9(1):15-33

Abstract. Driftwood, prop roots and other mangrove samples were collected from the intertidal regions of Brillant and Anse Boileau mangrove stands, in the Seychelles. This material was examined for the presence of higher marine fungi. Forty seven species of marine fungi were collected (37 Ascomycotina , 1 Basidiomycotina, 9 Deuteromycotina) , with Halocypluna villosu the most common fungus, while Aniptodera mungrovii, Antennospora quudricorruita, Halosarpheia marina , Ascomyccte sp. (4), and Lulworthiu grandispora were collected frequently. The mycota of the two mangrove stands arc compared. A list of fungi recorded from mangroves is compiled.  相似文献