海洋油-水环境下钢铁设施表面腐蚀微生物膜群落特征及其加速的腐蚀破坏机理研究

Marine underwater facilities, such as wharf steel piles, offshore and deep-sea oil production facilities, undersea oil pipelines, ship ballast water tanks as well as similar crude oil storage tanks, and so on, are important public and infrastructure industry facilities of our country. Their corrosion damage could result in enormous economic cost. So, it is significant to carry on the researches on the key corrosion processes and mechanisms. Localized corrosion, even pitting corrosion and corrosion cracking often occur on these facilities. Corrosive microorganisms is generally considered as one of the critical factors of corrosion damage. On account of the facilities serving environment or possible oil-spilled pollution, corrosion of these facilities actually occur in the oil-water or oil-mud-interstitial water environment. The petroleum microorganism would affect even change the community characteristic of the corrosion biofilm, and then influence the corrosion mechanism. In this project, we suggested to carry the research on the petroleum corrosion biofilm community characteristic and their effect on the accelerated corrosion mechanism of steel facilities under oil-water environment. Microbial community ecology, typical corrosion bacteria strain culture and the biofilm biochemical micro-environment are carried out and the related technique and method will be established. Localized corrosion process influenced by key corrosion bacteria will be researched to clarify the corrosion damage mechanism influenced by the bacteria and microbial corrosion mechanism in the oil-water environment is clarified. These researches would provide significant scientific basis for the microbial corrosion damage analysis, identification and monitoring technique for marine facilities as well as the corrosion protection technologies development.

海洋水下设施诸如港湾码头钢桩、近海和深远海采油设施、海底输油输水管线、船舶压载水舱及类似的原油储罐设施等，是国家重要公共和基础工业设施。一旦发生腐蚀破坏，会造成巨大损失。研究其关键腐蚀破坏过程与机理具有重要意义。这些设施常常发生局部腐蚀、甚至发生穿孔和断裂，腐蚀微生物已被公认为关键的腐蚀破坏因素之一。由于设施运行环境或溢油污染等，腐蚀实际是常发生在油-水或油-泥-间隙水环境下，其中的石油微生物会影响甚至改变腐蚀微生物膜群落特征，并进而影响腐蚀破坏机理。本项目提出研究钢铁设施油-水环境下其表面石油腐蚀生物膜群落特征及其影响的加速腐蚀破坏机理，将开展微生物群落生态、典型腐蚀微生物筛选及生物膜生化微环境等研究，建立相关技术和方法，开展关键腐蚀微生物局部腐蚀破坏过程研究，弄清油-水环境下微生物腐蚀破坏机理，有望为海洋工程设施微生物腐蚀破坏的分析、鉴定与检监测技术及腐蚀防护技术发展提供重要科学依据。

在真实海洋环境中，金属材料的微生物腐蚀常常发生在油水环境中。石油降解过程中参与的微生物及其代谢产物会影响甚至改变金属表面的腐蚀微生物膜群落及其生化微环境，并进而影响金属设施的腐蚀破坏行为和机理。因此本项目首先研究了无油污污染的实海中金属表面腐蚀微生物群落组成及其可能的腐蚀机理。研究发现，在实海环境中不同金属材料表面的腐蚀微生物群落和腐蚀机理不同：硫酸盐还原菌（SRB）是碳钢表面主要的腐蚀微生物，且从外锈层至内锈层分布着不同属的SRB；产甲烷古菌与SRB共存于锈层中共同影响金属腐蚀；铜合金表面主要形成以耐铜毒性的兼性厌氧菌为主的微生物群落，低丰度的SRB和硫酸盐还原反应关键编码基因dsr说明铜合金的微生物腐蚀并非由SRB及其产生的硫化物引发。与无油海水相比，添加原油促进了金属腐蚀速率，不仅使海水浮游微生物转变成以石油降解微生物如Alcanivorax为主的群落结构，也改变了金属表面附着微生物的结构组成：产酸菌首先在金属表面占优势，而后SRB多样性和丰度开始增多，这也表明海水中添加原油时，前期主要是产酸菌引发微生物腐蚀，而后当碳源浓度降低时SRB成为主要的腐蚀微生物。为进一步研究典型微生物的腐蚀机理，我们利用传统的微生物分离技术在好氧、厌氧以及兼性厌氧条件下对实海腐蚀产物的腐蚀微生物进行分离纯化，共分离培养了42株可能的腐蚀菌株，对其中部分菌株局部腐蚀机理以及胞外电子传递机制进行研究：发现类Bacillus sp.具有和SRB相似的腐蚀行为特点，加速碳钢的腐蚀并引发孔蚀；胞外电子传递介导物质吩嗪促进铜绿假单胞菌向平衡电位电极的电子转移，从而促进了该腐蚀微生物在厌氧条件下生长。本项目建立了以高通量测序手段为主，发现在实际海洋油水环境中的指标腐蚀微生物的检测方法，且有助于对营养物质添加下海水微生物腐蚀机理形成更深入全面的认识，对微生物腐蚀控制和检测技术也具有重要的借鉴意义。