天然海水中微生物膜对碳钢腐蚀行为的影响

通过对比碳钢在天然海水和灭菌海水中的腐蚀行为,研究海洋微生物对碳钢材料的腐蚀行为的影响.结果表明,海洋微生物可在碳钢表面形成微生物膜,其对碳钢腐蚀速率的影响及作用机理与微生物的种类密切相关.在腐蚀初期,海洋微生物膜对碳钢的腐蚀起到了抑制作用,主要由多种好氧微生物协同作用的结果;在腐蚀后期,随着海洋微生物膜增厚导致厌氧腐蚀的出现从而加速腐蚀,主要是硫酸盐还原菌等厌氧微生物的作用.     

金属大气腐蚀实验方法进展与研究动态

金属材料及其制品与所处的自然环境间因环境因素的作用而引起材料变质或破坏称为金属材料的大气腐蚀。金属材料的大气腐蚀机制主要是材料受大气中所含的水分、氧气和腐蚀性介质的联合作用而引起的破坏。按腐蚀反应可分为化学腐蚀和电化学腐蚀两种，在干燥无水分的大气环境中发生的腐蚀属化学腐蚀，其它情况下均属于电化学腐蚀，但它又别于全浸在电解液中的电化学腐蚀，它是在电解液薄膜下的电化学腐蚀，水膜的厚度及干湿交变频率、氧的扩散速度等因素，都影响着大气腐蚀的过程与速度。     

硫酸盐还原菌对海水状态和碳钢腐蚀行为的影响

采用溶液环境参数和电极电化学参数测量技术研究了海水中硫酸盐还原菌生长和衰亡过程对溶液状态和D36碳钢腐蚀过程的影响。结果表明,硫酸盐还原菌通过新陈代谢作用把溶液中的硫酸盐转化为硫离子而增大了氧化还原电位和酸度,并导致D36钢的腐蚀电位负移和腐蚀速度增加。极化曲线和电化学阻抗谱证实,虽然金属腐蚀过程在上述过程中并未发生机理性变化,但阳极过程和部分阴极过程的加速是腐蚀速度增加的主要原因。上述结果同时表明．硫酸盐还原菌本身和新陈代谢中间体并未直接参与腐蚀过程,主要是通过产生的硫离子改变溶液状态来加速腐蚀过程的。     

钛/碳钢在海水中电偶腐蚀的研究

研究了国产纯钛和碳钢Q235在青岛近海海水中的电偶腐蚀情况。测定这两种金属材料的自然腐蚀电位和失重速率；用IM6e电化学工作站测定两种金属材料在海水中的稳态极化曲线，研究其极化性能；测定了碳钢与钛组成不同面积比、不同温度、不同海水流速时电偶电流的大小、方向，电偶电位，以及不同面积比时阳极的失重速率。结果表明，阳极的腐蚀速率随阴／阳极面积比、环境温度、海水流速的增大而增加，且阳极腐蚀速率随阴／阳极面积比的增大趋于极限值。     

低合金钢在海水中腐蚀电化学行为的研究

本文采用微区电位扫描法,恒电流阶跃法、恒电位阶跃法等多种电化学方法,研究了两种在海水中抗腐蚀性能明显不同的低合金钢其腐蚀电化学行为的差异。结果表明,这种差异同低合金钢的抗腐蚀性能存在着一定的对应关系。     

海洋大气及污染海洋大气对典型钢腐蚀的影响

对典型钢(碳钢Q235和耐候钢09CuPCrNi)在海洋大气(麦岛)和污染海洋大气(团岛)环境中进行了2年的暴露腐蚀实验,并测试了其环境的大气污染因子。结果显示典型钢在团岛的腐蚀明显地比麦岛重,团岛的氯离子浓度几乎是麦岛氯离子浓度的3倍。讨论了海洋大气和污染海洋大气对典型钢的腐蚀作用的差异。     

利用穆斯堡尔谱对普碳钢在海洋各腐蚀区带锈层的研究

穆斯堡尔效应(M?ssbauer Effect)是一种固体中原子核对γ-射线的无反冲共振吸收或发射的现象,即γ-射线的共振荧光现象。利用穆斯堡尔谱研究腐蚀过程和腐蚀产物,近年来越来越受到国内外有关学者的重视(Meisel,1980)。穆斯堡尔谱是一种非破坏性结构测试手段,它不仅能研究晶态产物,也能研究非晶态产物,比X衍射等方法优越得多(夏元复等,1984)。自70年代末起,国内外开始出现一些关于海水中钢铁腐蚀产物研究的报道(Peev,1978;马如璋等,1981;吴继勋等,1982;陈俊明等,1982;郑裕芳等,1983),而用ME对在整个海洋环境中各个不同腐蚀区带钢铁的腐蚀产物的研究迄今还尚未见报道。作者于1994年10月在埕岛海区对挂片的腐蚀锈层的结构组成进行了穆斯堡尔谱分析,以探讨在各不同区带的腐蚀产物的差异及腐蚀机理,为开发耐海水腐蚀钢和普碳钢的防腐提供了理论依据。     

腐蚀电化学技术在海水循环冷却系统中的应用

腐蚀问题是海水循环冷却系统的主要问题之一,腐蚀电化学技术是研究解决该问题的重要手段。文章以线性极化、弱极化、强极化和电化学阻抗谱技术为重点,分别介绍不同电化学方法的技术特点和可获得的腐蚀参数,分析其在海水循环冷却系统中应用的优势和不足,为研究海水循环冷却系统的金属腐蚀机理和腐蚀防护手段提供理论支撑和指导,同时也为海水循环冷却工艺运行和水处理方案提供决策建议。     

青岛近海碳钢锈层中细菌群落结构的多样性

研究海水环境中Q235碳钢锈层中微生物群落的多样性。应用16SrDNA基因文库技术,分别对实海全浸一年的Q235碳钢内外锈层中的微生物进行基因文库的构建和分析。通过克隆测序构建了含有64个OTUs的细菌16SrRNA基因文库,结果表明锈层中微生物种类丰富,主要分布于13个已知的菌门,包括变形菌门;拟杆菌门;硅藻门;酸杆菌门;浮霉菌门;硝化螺旋菌门;厚壁菌门;绿弯菌门;疣微菌门;绿菌门;放线菌门;红藻门以及螺旋体门。内外锈层的优势菌均为变形细菌门,分别占文库序列的46%和53%,其中α-变形菌纲又为门中优势类群,但在内外锈层中还存在明显的系统发育学分歧。     

天然海水中硫酸锌、葡萄糖酸钙和APG等复合碳钢缓蚀剂的研究

通过正交实验确定了硫酸锌、葡萄糖酸钙和 APG(C0 81 0 )复配的 3元缓蚀剂最佳复配比为4∶ 1∶ 2。用失重法测得该 3元缓蚀剂在 35 0 mg/ L时对碳钢缓蚀率为 92 .8%,但试样表面存在局部腐蚀。为了抑制试样局部腐蚀的发生 ,采用失重法从几种常用缓蚀组分中筛选出硅酸钠和钨酸钠作为 3元缓蚀剂的添加剂组成 5元缓蚀剂 ,通过正交实验确定了组分间的最佳复配比。用失重法确定了5元缓蚀剂的临界浓度为 2 80 mg/ L ,此时对碳钢缓蚀率为 93.8%,并有效抑制了局部腐蚀的发生。从而得到了天然海水中 1种有效抑制碳钢局部腐蚀的低毒、高效复合缓蚀剂。据极化曲线分析可以确定该 5元缓蚀剂是 1种抑制阳极过程为主的混合型缓蚀剂。     

复配型席夫碱缓蚀剂对碳钢在海水中缓蚀性能研究

设计了由邻氧乙酸苯甲醛-4-吡啶甲酰腙席夫碱80 mg/L,邻香草醛脱氢枞胺席夫碱6 mg/L,ZnSO4 50 mg/L,Tween-80 100 mg/L四元复配缓蚀剂,通过失重法、极化曲线法和电化学交流阻抗技术,研究了该复配缓蚀剂在模拟现实使用环境中的缓蚀性能。结果表明,该复配缓蚀剂的缓蚀率受海水盐度的影响不大,但该复配缓蚀剂的缓蚀性能受海水温度和海水流速的影响较大,当温度低于50℃和流速较低、缓蚀剂浓度为临界浓度时,缓蚀剂对碳钢有很好的抑制作用,而有锈试样和间浸实验发现高浓度的复配缓蚀剂可以抑制碳钢的腐蚀。     

海水流动对A3钢腐蚀速度的影响

为了定量考察海水的流动对钢铁材料在海水中的腐蚀速度的影响,通过室内和实海挂片失重测试比较了A3钢在静止和流动海水中的腐蚀速度差异,并在控制流速条件下使用动电位法测试了A3钢的腐蚀速度,同时测试了不同流速海水中的环境参量。室内和实海挂片失重测试比较结果表明,海水流动能够加快A3钢在海水中的腐蚀速度,腐蚀初期尤其明显。在控制流速条件下采用动电位极化方法测试了腐蚀初期A3钢的腐蚀速度,并且通过拟合处理得到了海水流动对其腐蚀速度影响因子的表达式。     

Probabilistic lifetime assessment of marine reinforced concrete with steel corrosion and cover cracking

In order to study the durability behavior of marine reinforced concrete structure suffering from chloride attack,the structural service life is assumed to be divided into three critical stages,which can be characterized by steel corrosion and cover cracking.For each stage,a calculated model used to predict the lifetime is developed.Based on the definition of durability limit state,a probabilistic lifetime model and its time-dependent reliability analytical method are proposed considering the random natures of influencing factors.Then,the probabilistic lifetime prediction models are applied to a bridge pier located in the Hangzhou Bay with Monte Carlo simulation.It is found that the time to corrosion initiation t0 follows a lognormal distribution,while that the time from corrosion initiation to cover cracking t1 and the time for crack to develop from hairline crack to a limit crack width t2 can be described by Weibull distributions.With the permitted failure probability of 5.0%,it is also observed that the structural durability lifetime mainly depends on the durability life t0 and that the percentage of participation of the life t0 to the total service life grows from 61.5% to 83.6% when the cover thickness increases from 40 mm to 80 mm.Therefore,for any part of the marine RC bridge,the lifetime predictions and maintenance efforts should also be directed toward controlling the stage of corrosion initiation induced by chloride ion.     

海洋环境中平台钢腐蚀速率的三层BP 神经网络预测

利用三层BP神经网络预测海洋环境因素对材料的腐蚀速率的影响。结合实测的pH值、温度、溶解氧、盐度、生物附着等影响因素,分析了上述环境因素对平台钢腐蚀的影响,建立环境因素与腐蚀速率之间的映射关系,预测了平台钢在海洋环境中的腐蚀速率。结果表明,全浸区腐蚀速率预测误差为6.95%,潮差带腐蚀速率预测误差为4.2%,预测精度较高。说明利用三层BP神经网络预测钢在海水中腐蚀速率技术可行,具有较高的预测精度和应用价值。     

An isotopic perspective on the correlation of surface ocean carbon dynamics and sea ice melting in Prydz Bay (Antarctica) during austral summer

The stable carbon isotope composition of particulate organic carbon (δ¹³C_POC) and naturally occurring long-lived radionuclide ²²⁶Ra (T_1/2=1600 a) were applied to study the variations of upper ocean (<100 m) carbon dynamics in response to sea ice melting in Prydz Bay, East Antarctica during austral summer 2006. Surface δ¹³C_POC values ranged from −27.4‰ to −19.0‰ and generally decreased from inner bay (south of 67°S) toward the Antarctic Divergence. Surface water ²²⁶Ra activity concentration ranged from 0.92 to 2.09 Bq/m³ (average 1.65±0.32 Bq/m³, n=20) and increased toward the Antarctic Divergence, probably reflecting the influence of ²²⁶Ra-depleted meltwater and upwelled ²²⁶Ra-replete deep water. The fraction of meltwater, f_i, was estimated from ²²⁶Ra activity concentration and salinity using a three-component (along with Antarctic Summer Surface Water, and Prydz Bay Deep Water) mixing model. Although the fraction of meltwater is relatively minor (1.6–11.9%, average 4.1±2.7%, n=20) for the surface waters (sampled at ~6 m), a positive correlation between surface δ¹³C_POC and f_i (δ¹³C_POC=0.94×f_i−28.44, n=20, r²=0.66, p<0.0001) was found, implying that sea ice melting may have contributed to elevated δ¹³C_POC values in the inner Prydz Bay compared to the open oceanic waters. This is the first time for a relationship between δ¹³C_POC and meltwater fraction to be reported in polar oceans to our knowledge. We propose that sea ice melting may have affected surface ocean δ¹³C_POC by enhancing water column stability and providing a more favorable light environment for phytoplankton photosynthesis, resulting in drawdown of seawater CO₂ availability, likely reducing the magnitude of isotope fractionation during biological carbon fixation. Our results highlight the linkage of ice melting and δ¹³C_POC, providing insights into understanding the carbon cycling in the highly productive Antarctic waters.     

Effects of sea roughness and atmospheric stability on wind wave growth

The paper considers the effects of sea roughness and atmospheric stability on the wind wave growth by using the logarithmic boundary layer profile including a stability function, as well as adopting Toba et al.'s [J. Phys. Ocean. 34 (1990) 705] significant wave height formula combined with some commonly used sea surface roughness formulations. The wind wave growth is represented by the non-dimensional total wave energy relative to that for neutral stability used by Young [Coast. Engng 34 (1998) 23]. For a given velocity at the 10 m elevation, spectral peak period and stability parameter, the wind wave growth is determined.     

钢渣在海洋中无机固碳行为及其应用

钢渣是钢铁生产过程中的副产物,是一种放错的资源。钢渣投放在水体中可显著提升水体pH值,并能吸收大量的CO₂。为了解钢渣投放在海洋中可能引起的pH变化及其无机固碳能力,本研究考察了不同粒径、钢渣含量、初始pH及是否扰动等条件下钢渣/海水的pH变化特征和固碳能力。结果表明,不同条件下的钢渣/海水体系,随着浸泡时间的延长,浸出液pH初期都快速升高,后期趋于平缓,且钢渣粒径越小、投入钢渣含量越多及外加振荡作用,都可使浸出液pH提升;同时,浸出液能维持的pH水平对钢渣/海水体系固碳效率影响较大,而钢渣粒径的大小是钢渣固碳能力的最直接影响因素。本工作结果还表明,在实海环境中投放一定量的钢渣有助于预防局部水体酸化,并起到固碳减排的目的。     

High concentrations of exopolymeric substances in Arctic winter sea ice: implications for the polar ocean carbon cycle and cryoprotection of diatoms

Exopolymeric substances (EPS) produced by microorganisms play important roles in various aquatic, porous, and extreme environments. Only recently has their occurrence in sea ice been considered. We used macroscopic and microscopic approaches to study the content and possible ecological role of EPS in wintertime fast ice near Barrow, Alaska (71°20′ N, 156°40′ W). Using Alcian blue staining of melted ice samples, we observed high concentrations of EPS in all samples examined, ranging from 0.79 to 7.71 mg xanthan gum equivalents (XGEQV) l⁻¹. Areal conversions to carbon equivalents yielded 1.5−1.9 g C m⁻² ice in March and 3.3−4.0 g C m⁻² in May (when the ice was thicker). Although EPS did not correlate with macronutrient or pigment data, the latter analyses indicated ongoing or recent biological activity in the ice within temperature horizons of −11°C to −9°C and warmer. EPS correlated positively with bacterial abundance (although no functional relationship could be deduced) and with dissolved organic carbon (DOC) concentrations. Ratios of EPS/DOC decreased at colder temperatures within the core, arguing against physical conversion of DOC to EPS during freezing. When sea-ice segments were maintained at representative winter temperatures (−5°C,−15°C and −25°C) for 3−14 months, the total EPS content increased significantly at rates of 5−47 μg XGEQV l⁻¹ d⁻¹, similar to published rates of EPS production by diatoms. Microscopic images of ice-core sections at these very cold temperatures, using a recently developed non-invasive method, revealed diatoms sequestered in spacious brine pockets, intact autofluorescent chloroplasts in 47% of the (pennate) diatoms observed, and indications of mucus in diatom-containing pores. The high concentrations of EPS detected in these winter ice cores represent a previously unrecognized form of organic matter that may contribute significantly to polar ocean carbon cycles, not only within the ice but after springtime release into the water column. The EPS present in very high concentrations in the brine of these microhabitats appear to play important buffering and cryoprotectant roles for microorganisms, especially diatoms, against harsh winter conditions of high salinity and potential ice-crystal damage.