Benthic status of near-shore fishing grounds in the central Philippines and associated seahorse densities     

Marcus JE  Samoilys MA  Meeuwig JJ  Villongco ZA  Vincent AC 《Marine pollution bulletin》2007,54(9):1483-1494

Benthic status of 28 near-shore, artisanal, coral reef fishing grounds in the central Philippines was assessed (2000-2002) together with surveys of the seahorse, Hippocampus comes. Our measures of benthic quality and seahorse densities reveal some of the most degraded coral reefs in the world. Abiotic structure dominated the fishing grounds: 69% of the benthos comprised rubble (32%), sand/silt (28%) and dead coral (9%). Predominant biotic structure included live coral (12%) and Sargassum (11%). Rubble cover increased with increasing distance from municipal enforcement centers and coincided with substantial blast fishing in this region of the Philippines. Over 2 years, we measured a significant decrease in benthic 'heterogeneity' and a 16% increase in rubble cover. Poor benthic quality was concomitant with extremely low seahorse densities (524 fish per km(2)). Spatial management, such as marine reserves, may help to minimize habitat damage and to rebuild depleted populations of seahorses and other reef fauna.  相似文献   

Development of a methodology for assessing the environmental impact of radioactivity in Northern Marine environments     

Brown JE  Hosseini A  Børretzen P  Thørring H 《Marine pollution bulletin》2006,52(10):1127-1137

The requirement to assess the impacts of radioactivity in the environment explicitly and transparently is now generally accepted by the scientific community. A recently developed methodology for achieving this end for marine ecosystems is presented within this paper. With its clear relationship to an overarching system, the marine impact assessment is built around components of environmental transfer, ecodosimetry and radiobiological effects appraisal relying on the use of "reference organisms". Concentration factors (CFs), dynamic models and, in cases where parameters are missing, allometry have been employed in the consideration of radionuclide transfer. Dose conversion coefficients (DCCs) have been derived for selected flora and fauna using, inter alia, dose attenuation and chord distribution functions. The calculated dose-rates can be contextualised through comparison with dose-rates arising from natural background and chronic dose-rates at which biological effects have been observed in selected "umbrella" endpoints.  相似文献   

Carbon,nitrogen, phosphorus and heavy metal budgets: How large is the eelgrass (Zostera marina L.) sink in a temperate estuary?     

Kaldy JE 《Marine pollution bulletin》2006,52(3):342-353

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Field accumulative behavior of organochlorine pesticides. The role of crabs and sediment characteristics in coastal environments     

Menone ML  Miglioranza KS  Botto F  Iribarne O  Aizpún de Moreno JE  Moreno VJ 《Marine pollution bulletin》2006,52(12):1717-1724

The influence of intertidal crab beds on the concentrations of organochlorine (OC) pesticides in sediment was studied in two different coastal environments in Argentina. Samples of male burrowing crabs (Chasmagnathus granulatus) were collected for this study. Our field data showed lower bioaccumulation of OC pesticides in crabs from sediments with a higher total organic carbon (TOC) and higher clay content. Thus, concentrations in crabs depend on the physico-chemical characteristics of the sediment where they live more than on the OC pesticide concentrations in the environment. The distribution patterns in sediment from inside and outside crab burrows were similar for both coastal areas being HCHs  γ-chlordane > p,p′-DDE for San Antonio Bay (SAO), and HCHs > p,p′-DDE  γ-chlordane for Mar Chiquita (MCh) coastal lagoon. OC pesticide concentrations in sediment were significantly lower inside than outside crab burrows, irrespective of the sediment physico-chemical characteristics due to the bioturbation activity of C. granulatus.  相似文献   

建筑结构基础隔震技术的研究和应用   总被引：3，自引：0，他引：3  

陆鸣  田学民  王笃国  李丽媛 《震灾防御技术》2006,1(1):31-38

本文介绍了建筑结构基础隔震基本原理、隔震系统分类、隔震技术进展、隔震设计一般流程、隔震相关专著、隔震规范和应用软件,并提出隔震技术推广中有待解决的几个问题。  相似文献   

冻结食品解冻时间的数值计算   总被引：3，自引：0，他引：3  

关志强  戴午子 《广东海洋大学学报》1999,19(4):45-48

给出描述平板状冻结食品解冻过程和数学模型，并用有限差分法求解。以牛肉为例，通过与实测值和经验公式计算值进行比较，结果表明，数值法预测冻结食品解冻时间具有较高的精度。  相似文献   

硬岩凿岩机的自动化     

鸣午据 《探矿技术》1994,(2):18-19

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瑞典阿特拉斯·科普科的水文水井钻机          下载免费PDF全文

鸣午 《探矿工程》1980,(1)

Rotamec 1302型车装全液压回转钻机能准确控制加减压，立轴高扭矩，大范围立轴速度，大排量的空气洗井和高压空气，使这种钻机同样适用潜孔锤钻进，就象用牙轮钻头钻进一样。1302型钻机可用于大口径的深水井钻进（见图1）。潜孔锤一般用于中硬—很硬层。钻头的直径范围，建议为152—304毫米。大口径潜孔锤和钻头达380毫米，一般需用额外的空压机或泡沫洗井。使用空气或泡沫洗井时，有效的工作深度取决于  相似文献   

介绍一种隧道排水沟防冻方式     

乜风鸣 《冰川冻土》1980,(1)

隧道开挖中或建成后,一般都会遇到围岩中的水向隧道周围汇集的情况。在严寒及多年冻土地区隧道设计中若对地下水处理不当,便会产生种种有害的后果,如:由于冻胀而使衬砌酥碎、剥落、开裂、破坏等,大大降低了建筑物的使用寿命;由于线路严重冻胀隆起,衬砌变形而使限界减小;积冰挂冰严重侵入限界而危及行车安全。为此必须重视隧道排水沟防冻问题。我国铁路建设者在严寒及多年冻土隧道中曾用过泄水洞、深  相似文献   

Reactive sulfides relationship with metals in sediments from an eutrophicated estuary in Southeast Brazil   总被引：5，自引：0，他引：5  

Machado W  Carvalho MF  Santelli RE  Maddock JE 《Marine pollution bulletin》2004,49(1-2):89-92

The potential association of acid-volatile sulfides (AVS) and reactive (HCl soluble) Fe with the distribution of reactive trace metals (Cu, Cd, Ni, Pb and Zn) was investigated in sediment cores collected in the Igua?u river estuarine system (Guanabara bay, Brazil), within the river (core R) and the bay (core B) areas. Moderate to extremely high AVS concentrations (33-314 micromol g(-1)) were found in the rapidly-accumulated sediments of this eutrophicated estuary. AVS showed significant correlations with Fe, Ni and Pb in core B, whereas no correlation between AVS and metals was observed in core R. Results suggest that the AVS:Fe molar ratio may often reflect the diagenetic conditions controlling the distribution of Cd and Cu in core B better than AVS and Fe levels themselves. A shift in the biogeochemical controls of metal distribution from the river to the open bay sediments is suggested, with a greater association of most metals with AVS and Fe in bay sediments.  相似文献