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目前，在中国采用热浸镀Zn及其合金一直是防止钢材在自然环境中腐蚀的最经济有效的方法，为了提高镀层的防腐和涂装性能，往往在其表面进行钝化处理。传统的镀锌层钝化处理工艺均采用高浓度的铬酸盐溶液， 这对环境污染和人体的危害较严重。随着环境保护问题日益引起人们的重视，在传统的高铬钝化基础上，低浓度铬酸盐钝化开始步入实用性阶段(吴双成，1996；卢燕平等，1995)。但是，目前低铬钝化研究主要集中于热浸镀Zn或电镀Zn镀层，而合金镀层由于化学稳定性高，与铬酸溶液自发反应能力差，无法采用常规的低铬钝化方法处理，有关这方面的报道目前尚少。王洪仁(1998)对Zn-Al合金镀层的低铬钝化处理进行了有益的探索，获得了一个优化的低铬钝化配方和稳定的钝化工艺，并成功地应用于热浸镀Zn-Al合金镀层的表面防锈处理；实验证明，海水在模拟浸泡6个月后，钝化处理Zn-Al合金镀层的腐蚀失重比未钝化样品降低65.9%，表明低铬酸盐钝化使Zn-Al合金镀层的耐海水腐蚀性能得到显著提高(Li Y et al.，2001)。本文作者在前人基础上对Zn-Al合金镀层低铬钝化膜的组成和耐盐雾腐蚀性进行了研究，并初步探讨了钝化膜的形成过程及其耐蚀机理。对Zn-Al合金镀层低铬钝化处理技术的研究，不仅大大降低了对环境的污染和人体的危害，也是在低铬钝化研究方面的重大突破，具有十分重要的意义和实际应用价值。 相似文献
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热浸镀用锌及锌铝合金的恒电流电化学性能 总被引：3，自引：0，他引：3
在海水腐蚀过程中，热浸镀层金属(或合金)对钢铁基体的阴极保护作用是很重要的因素，只有驱动电位大且稳定、电流效率高、表面腐蚀均匀的镀层才能保证钢材在海水中使用长久。作按照国标GB／T171848-1999的要求对几种典型的热浸镀用锌及锌铝合金测试了开路电位、工作电位，计算了电流效率，观察了腐蚀产物脱落情况及腐蚀均匀性，评价了各种典型镀层金属(合金)的电化学保护性能。研究表明，Zn的电化学性能最好，Zn-55A1-1．6Si合金的电化学性能最差，Zn-5Al-0．2RE、Zn-5Al-0．1Mg、Zn-6Al-3Mg、Zn-11AL-3Mg-0．2Si、Zn-25AL-0．2Mg-0．2Si和Zn-25Al-0．2RE-0．2Si合金介于二之间。 相似文献
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目前,在中国采用热浸镀Zn及其合金一直是防止钢材在自然环境中腐蚀的最经济有效的方法,为了提高镀层的防腐和涂装性能,往往在其表面进行钝化处理。传统的镀锌层钝化处理工艺均采用高浓度的铬酸盐溶液,这对环境污染和人体的危害较严重。随着环境保护问题日益引起人们的重视,在传统的高铬钝化基础上,低浓度铬酸盐钝化开始步入实用性阶段(吴双成,1996;卢燕平等,1995)。但是,目前低铬钝化研究主要集中于热浸镀Zn或电镀Zn镀层,而合金镀层由于化学稳定性高,与铬酸溶液自发反应能力差,无法采用常规的低铬钝化方法处理,有关这方面的报道目前尚少。… 相似文献
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镉镀层和锌镀层是海洋工程技术人员经常要选用的,它们都是保护性的镀层。然而,不同的使用环境。镉镀层和锌镀层的防护性能也不同,我们通过在海水、海洋大气和工业大气中的试验证实了这一点。在海水中镉镀层较锌镀层耐蚀,这一点通过在渤海海水中的237天挂片试验得到了验证。镉镀层在这样一段时间的海水浸泡中未有腐蚀现象,试片仍光亮,彩色钝化膜鲜艳;而锌镀层却有腐蚀,最大腐蚀面 相似文献
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南海东北陆坡区铁锰结核的特征和成因 总被引：4，自引：3，他引：4
对取自南海东北陆坡区的铁锰结核成分进行了X射线衍射，中子活化和电子探针研究，结核的组成矿物有δMnO2、针铁矿，水针铁矿，石英，斜长石，角闪石，钾长石，伊利石和白云母等。铁锰成分变化较大:Fe为7．1％－16．0％；Mn为5．8％－7．7％。Cu,Co,Ni,Pb含量低，分别为0．04％－0．06％、0．11％－0．15％、0．02％－0．03％和0．05％－0．07％，Mn/Fe比值为0．7。铁锰结核从内壳层向外壳层含铁量逐渐增加，Cu,Ni含量波动降低，反映在其形成过程中受到沉积环境波动，陆源碎屑物供给增加和Mn,Cu,Ni,Co元素来量变化的影响，具有典型边缘海水沉积成因铁锰结核的特征。 相似文献
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珍珠生长激素在合浦珠母贝育珠中的作用 总被引：5，自引：0，他引：5
以合浦珠母贝Ｐｉｎｃｔａｄａ ｍａｒｔｅｎｓｉｉ （Ｄｕｎｋｅｒ）作为珠母贝进行插核育试验,分别以其左、右边外套膜作为小片,并用珍珠生长激素浸泡小片,两个试验用珍珠生长激素浸光怕小片各插核育珠贝２００个,空白对组用海水浸泡小片插核育珠贝２０７个,育珠时间为６个多月。试验结束时,实验组珍珠的正圆珠率,白色珍珠比例以及珠层厚度在比空白对照组分别提高了９．２８％,２２．５７％和５２μｍ。 相似文献
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南海中部海域夏季水团的实测温盐深数据统计分析结果表明,研究区受南海暖池的影响,海域表层强度在28～31．5℃左右,呈北高南低、西高东低的特征;表层盐度在32～34．1psu左右,整体上呈南高北低、东高西低的分布特征。低盐区域主要分布在研究区西北部,与高温区域呈现重合的特点。综合研究表明,研究区受夏季风和海面净热通量的影响,海水层化作用较强,整体上混合层的厚度不大,温跃层比较发育,导致跃层的厚度比较大,最高可达170m,强度也较高,大部分区域温度梯度在0．09～0．12℃／m之间;盐跃层的上界深度和厚度整体上都低于温跃层。结合表层温度和盐度的分布特征推测研究区东部和南部表层海水存在着较厚的低温高盐水层。 相似文献
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Chandralata Raghukumar G. Sheelu P. A. Loka Bharathi Shanta Nair C. Mohandass 《Marine Georesources & Geotechnology》2001,19(1):1-16
In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance. 相似文献
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Arne Schnack-Friedrichsen Angela M. Davis Jim D. Bennell Dei G. Huws 《Marine Georesources & Geotechnology》2001,19(4):221-243
The interdependence between the seismo-acoustic properties of a marine sediment and its geotechnical/physical parameters has been known for many years, and it has been postulated that this should allow the extraction of geotechnical information from seismic data. Though in the literature many correlations have been published for the surficial layer, there is a lack of information for greater sediment depths. In this article, a desktop study on a synthetic seafloor model illustrates how the application of published near-surface prediction equations to subsurface sediments (up to several tens of meters burial depth) can lead to spurious predictions. To test this further, acoustic and geotechnical properties were measured on a number of sediment core samples, some of which were subjected to loading in acoustically-equipped consolidation cells (oedometers) to simulate greater burial depth conditions. For low effective pressures (representing small burial depths extending to around 10 meters subsurface), the general applicability of established relationships was confirmed: the prediction of porosity, bulk density, and mean grain size from acoustic velocity and impedance appears generally possible for the investigated sedimentary environments. As effective pressure increases through, the observed relationships deviate more and more from the established ones for the near-surface area. For the samples tested in this study, in some instances increasing pressure even resulted in decreasing velocities. There are several possible explanations for this abnormal behavior, including the presence of gas, overconsolidation, or bimodal grain size distribution. The results indicate that an appropriate depth correction must be introduced into the published prediction equations in order to obtain reliable estimates of physical sediment properties for greater subsurface depths. 相似文献
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海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。 相似文献
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Shigehisa Nakamura 《Marine Geodesy》2000,23(1):55-61
Specific properties of the interannual sea level variations and annual tides in the Northwestern Pacific were studied. Several tide stations were monitored. The monthly mean sea level for the year of 1995 was analyzed at each tide station. A seismic event in 1995, some tectonic activity around the subject area, and the Kuroshio (the oceanic western boundary current) may possibly contaminate results which would have occurred from the astronomical annual tide alone. 相似文献
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Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification
An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm. 相似文献
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The effect of different fixation and storage protocols on the flow cytometric (FCM) simultaneous analysis of bacterioplankton and phytoplankton in coastal seawater samples (Mediterranean coastal lagoons) was investigated. FCM measurements (cell number, fluorescence and scatter characteristics) were obtained through DAPI staining. Three fixatives [glutaraldehyde (GA), formaldehyde (FA) and paraformaldehyde (PFA)] and two storage (3 months duration) methods (5 °C and −196 °C) were tested. Two dominant populations were detected in studied samples: bacteria and eukaryotic picophytoplankton. Adding fixatives (2% final concentration) appears necessary to obtain FCM exhaustive counts of all the bacteria and phytoplanktonic cells. This was related to the permeation effect of fixatives which allowed a better DAPI staining of the cells. Maximum fluorescence, i.e. optimal staining of the cells was obtained with FA or PFA, and significant lower fluorescences with GA. Fixed samples stored at 5 °C induced rapid cell loss. Only storage in liquid nitrogen of samples fixed with FA or PFA, allows mid-term (≥4 months) preservation of bacteria or picophytoplankton cell numbers, and limited evolution of DAPI-induced fluorescence and scatter characteristics. 相似文献
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《海洋学报(英文版)》2014,(9):F0003-F0003
<正>Acta Oceanologica Sinica(AOS)is a comprehensive academic journal edited by the Editorial Committee of Acta Oceanologica Sinica and is designed to provide a forum for important research papers of the marine scientific community which reflect the information on a worldwide basis.The journal publishes scholarly papers on marine science and technology,including physics,chemistry,biology, 相似文献
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