海洋环境腐蚀与生物污损重点实验室知识库

海洋金属工程装备与设施是经略海洋、大力发展海洋经济的物质条件，但由于海洋环境的苛刻性，金属装备与设施在服役过程中不可避免的遭受海洋腐蚀的威胁。微生物腐蚀是一种非常重要的腐蚀形式，其引起的损失约占腐蚀总成本的20%。目前，关于海洋环境微生物腐蚀的研究大多集中于海水全浸区，而实际海洋环境中的水气交界处也存在着微生物腐蚀的风险。不同于单一全浸区腐蚀环境，水气交界处会同时暴露于海水和海洋大气中，这会使得腐蚀机制变得更加复杂。然而，微生物在水气交界处的腐蚀机制目前鲜有关注，因此，非常有必要开展海洋水气交界处微生物腐蚀机理的研究。本文以海洋平台及船舶用高强度EH40钢为研究对象，探究了海洋水气交界环境潮差区及水线微生物腐蚀机理。通过现场暴露，比较了潮差区及全浸区浸泡不同时间的样品的腐蚀行为差异，并结合样品表面微生物群落结构分析，阐明了海洋水气交界复杂环境对腐蚀微生物种群的影响。针对潮差区周期浸润环境，通过实验室模拟，分析了周期浸润所致生物膜变化与腐蚀变化的相关性，提出了周期浸润作用下海洋典型菌株对EH40钢的腐蚀影响机制。同时，针对水线，分析了海洋典型微生物在模拟静态及动态水线下的腐蚀行为，揭示了宏观氧浓差电池、生物膜及薄液膜对高强度钢腐蚀的耦合作用机制。主要研究结果如下：

（1）研究了EH40钢在潮差区与全浸区暴露不同时间后的腐蚀行为及表面微生物群落结构差异，获取了微生物群落随区带、时间的演变规律。相较于全浸区，潮差区金属样品的腐蚀速率更高。在3、9及15个月后，潮差区样品的腐蚀速率较全浸区的分别增加了5%、177%及106%。不同区带的EH40钢表面微生物群落存在明显差异。全浸区样品表面与硫循环相关的微生物种群更加丰富，Sulfurimonas及Desulfovibrio属的细菌是全浸区样品上的优势种群。充足的光照及氧气促进了潮差区样品表面藻类的生长，也使得能够进行光合作用并进行有氧呼吸的Kamptonema及Erythrobacter属的细菌作为优势种群存在。此外，浸泡时间对不同区带样品表面微生物群落的影响，主要表现在Vibrio及Lewinella属的菌种上。

（2）提出了周期浸润对铜绿假单胞菌作用下EH40钢腐蚀促进的增强机制。无菌环境下，相较于全浸条件，周期浸润样品的腐蚀速率增加了102%-139%。样品周期浸润时，其表面覆盖的薄液膜减少了氧气扩散路径，促进了阴极溶解氧还原反应，加速了无菌环境中样品的腐蚀。周期浸润环境下，铜绿假单胞菌对EH40钢的腐蚀促进效率从第7 d的18%上升到第14 d的47%。铜绿假单胞菌对周期浸润引起的环境胁迫的响应，促进了编码吩嗪化合物的基因的表达。相比全浸样品，14 d后，周期浸润样品上固着细胞的phzS基因、phzH基因和phzM基因显著上调，相对丰度分别增加了8倍、10倍和9倍。这些基因表达的上调使得周期浸润样品上生物膜中的吩嗪含量增加了53%，促进了周期浸润样品上铜绿假单胞菌的胞外电子传递，增强了铜绿假单胞菌在周期浸润条件下的腐蚀促进作用。

（3）揭示了周期浸润对泰坦尼克盐单胞菌作用下EH40钢腐蚀抑制的增强机制。无菌环境下，相较于全浸条件，周期浸润样品的腐蚀速率增加了46%-48%，这与样品表面薄液膜的存在相关。泰坦尼克盐单胞菌对EH40钢的腐蚀抑制率在全浸条件下为37%-58%，在周期浸润条件下为58%-80%。泰坦尼克盐单胞菌以氧气为电子受体，减小了薄液膜内部的溶解氧含量，抑制了EH40钢的腐蚀。同时，周期浸润样品表面固着细胞数量的增加及细胞内电子传递链中相关基因的表达上调促进了泰坦尼克盐单胞菌的有氧呼吸作用，增强了其在周期浸润条件下的腐蚀抑制作用。

（4）解析了静态水线下铜绿假单胞菌对EH40钢的腐蚀作用，揭示了铜绿假单胞菌与宏观氧浓差电池共同作用下的腐蚀机制。在无菌条件下，水线处表现出典型的宏观氧浓差电池特征，水线下方可分为三个区域：靠近水线处的阴极区、阴阳极相互交叉区域、阳极区。铜绿假单胞菌的存在扩大了水线下阳极区域，导致水线下阳极占比在90%以上，这进一步加速了水线下金属的腐蚀。同时，随着薄液膜的扩展及细菌的附着，最大阴极电流会由水线处转移到水线上方薄液膜覆盖的区域。

（5）揭示了动态水线下泰坦尼克盐单胞菌、薄液膜及宏观氧浓差电池三者对腐蚀的耦合作用机制。无论是无菌还是有菌环境，动态水线区作为阴极区域存在，水线下方作为阳极区存在。动态水线区域薄液膜的存在会增大水线下方的阳极区电流密度，增强电偶效应，加速水线下方金属的腐蚀。泰坦尼克盐单胞菌的存在会使得水线处的极性由无菌环境下的阴极转变为阳极，这与泰坦尼克盐单胞菌的较强的有氧呼吸作用有关。同时，动态水线区域泰坦尼克盐单胞菌的腐蚀抑制率更高，约为水线下区域的2倍，这进一步减弱了动态水线区的腐蚀。

Marine metal engineering equipment and facilities are the basis for the utilization of marine resources and the development of the marine economy. However, the metal equipment and facilities are inevitably threatened by corrosion during service because of harsh marine environments. Microbiologically influenced corrosion (MIC) is a very important corrosion form, causing about 20% losses of the total corrosion cost. At present, the research on MIC of marine mostly focused on full immersion zone. However, there is also a risk of MIC at the interface of seawater and air. Different from the single corrosive environment of the full immersion zone, metals in the seawater/air interface are exposed to two kinds of environments, resulting in the complexity of the corrosion mechanisms. Unluckily, the corrosion mechanisms of MIC at the seawater/air interface are rarely paid attention to. Therefore, it is highly desirable to study the MIC mechanisms at the seawater/air interface. The high-strength EH40 steel for marine platforms and ships has been selected as the research subject in this article. The MIC mechanisms in tidal and water-line zones with seawater/air interface are explored. The differences in corrosion rates of EH40 steel coupons exposed to tidal and full immersion zones at different times were evaluated by field exposure. Combined with the analysis of the surface microbial communities, the impact of complex environments at seawater/air interface on the corrosive microbial population was clarified. Based on the alternate immersion of the tidal zone, the correlation between biofilm changes and corrosion changes caused by alternate immersion was analyzed through laboratory simulation. The corrosion mechanisms of typical marine bacteria towards EH40 steel under alternate immersion were proposed. Meanwhile, the corrosion behaviors of typical marine bacteria under the simulated static and dynamic water-line environments were analyzed, revealing the coupling mechanisms of oxygen concentration cells, biofilms, and thin electrolyte layer on corrosion of EH40 steel. The main findings of this paper are as follows:

(1) The corrosion behavior and surface microbial communities of EH40 steel exposed to tidal and full immersion zones at different times were studied, and the succession law of microbial communities was obtained. The corrosion rate of coupons in the tidal zone was higher than that in the full immersion zone. After 3, 9, and 15 months, the corrosion rate of coupons in the tidal zone increased by 5%, 177%, and 106% compared to that in the full immersion zone, respectively. There were significant differences in the microbial communities on coupons in the different zones. The species involved in the sulfur cycle were more abundant on the coupons in full immersion zone. The dominant genera on coupons in the full immersion zone were Sulfurimonas and Desulfovibrio. The adequate light and oxygen promoted the growth of algae and enrichment of species capable of photosynthesis and aerobic respiration on coupons in the tidal zone. The dominant genera on coupons in the full immersion zone were Kamptonema and Erythrobacter. In addition, the richness of Vibrio and Lewinella was influenced significantly by the exposure time of coupons.

(2) The mechanism of enhanced corrosion promotion of Pseudomonas aeruginosa towards EH40 steel under alternate immersion was proposed. In the sterile environment, the corrosion rate of coupons with alternate immersion increased by 102%-139% compared to that of full immersion. Under the alternate immersion, the thin electrolyte layer  on the metal surface promoted the cathodic oxygen reduction reaction by decreasing the path of oxygen diffusion, and accelerating the corrosion of coupons in the sterile environment. The corrosion promotion efficiency of P. aeruginosa on EH40 steel increased from 18% on the 7th day to 47% on the 14th day under the alternate immersion. The response of P. aeruginosa to environmental stress caused by alternate immersion promoted the expression of the genes encoding phenazines. After 14 days, compared to the full immersion condition, the relative abundance of phzS, phzH, and phzM genes of sessile cells on the coupons of alternate immersion increased by 8, 10 and 9 times, respectively. The expression upregulation of these genes increased the content of phenazines of biofilms on coupons of alternate immersion by 53%, which promoted the process of extracellular electron transfer and enhanced the corrosion efficiency of P. aeruginosa under the alternate immersion.

(3) The mechanism of enhanced corrosion inhibition of Halomonas titanicae towards EH40 steel under the alternate immersion was proposed. In the sterile environment, the coupons corrosion rate of the alternate immersion increased by 46%-48% compared to that of full immersion, which was related to the presence of TEL on the surface. The corrosion inhibition efficiency of H. titanicae on EH40 steel was 37%-58% under full immersion and 58%-80% under alternate immersion. H. titanicae used oxygen as an electron acceptor to consume the dissolved oxygen of TEL and inhibited the corrosion of EH40 steel. In addition, the increase in the number of sessile cells and the upregulation of genes in the electron transport chain of cells promoted aerobic respiration of H. titanicae, enhancing the corrosion inhibition efficiency under alternate immersion.

(4) The effect of P. aeruginosa on EH40 steel corrosion under the static water-line was analyzed, and the corrosion mechanism under the combination of P. aeruginosa and oxygen concentration cells was revealed. The results indicated that the water-line zone exhibited typical oxygen concentration cell phenomenon under the sterile condition. The area below the water-line could be divided into three parts: cathodes near the water-line, the area where the anodes and cathodes coexist, and the anodes. The presence of P. aeruginosa expanded the anode area below the water-line, resulting in an anode proportion of over 90%, which further accelerated the corrosion of metals below the water-line. Meanwhile, as the expansion of TEL and attachment of bacteria, the maximum cathodic current transferred from the position of water-line to the position covered by the TEL above the water-line.

(5) The collaborative mechanism of H. titanicae, TEL, and oxygen concentration cell on EH40 steel corrosion under the fluctuating water-line was revealed. Whether in the sterile or biotic media, cathodes mainly existed in the area of fluctuating water-line, and anodes existed in the area below the low water-line. The TEL on the area of fluctuating water-line increased the anodic current density below the low water-line, which enhanced the galvanic effect and accelerated the corrosion of area below the low water-line. The polarity of the low water-line area was changed from cathode to anode by H. titanicae, which was related to the aerobic respiration of H. titanicae. The corrosion inhibition efficiency of H. titanicae on the area of fluctuating water-line was about twice that on the area below the low water-line. The higher corrosion efficiency of H. titanicae on the area of fluctuating water-line weakened the corrosion of this area.

目  录

第1章 绪论      1

1.1 引言     1

1.2 微生物腐蚀机理研究进展 2

1.2.1 微生物腐蚀概述      2

1.2.2 铜绿假单胞菌腐蚀机理  5

1.2.3 泰坦尼克盐单胞菌腐蚀机理  6

1.3 海洋水气交界环境腐蚀研究进展     7

1.3.1 水气交界环境腐蚀概述  7

1.3.2 水气交界环境腐蚀机制及影响因素      7

1.4 微生物腐蚀研究方法 11

1.4.1 失重法      11

1.4.2 电化学法  12

1.4.3 腐蚀形貌表征方法  13

1.4.4 腐蚀产物表征方法  13

1.4.5 生物膜表征方法      14

1.4.6 微生物基因丰度表征方法      15

1.4.7 微生物代谢活性表征方法      16

1.5 选题依据及研究思路 16

1.5.1 选题依据  16

1.5.2 研究目标与内容      17

1.5.3 研究方案  18

第2章 海洋潮差区EH40钢腐蚀行为及微生物群落结构多样性研究 20

2.1 引言     20

2.2 实验材料与方法 20

2.2.1 实验材料  20

2.2.2 实海暴露  21

2.2.3 腐蚀速率表征  22

2.2.4 腐蚀形貌及腐蚀产物表征      22

2.2.5 微生物多样性分析  23

2.3 实验结果与讨论 23

2.3.1 腐蚀速率分析  23

2.3.2 腐蚀形貌分析  24

2.3.3 腐蚀产物分析  26

2.3.4 全浸区EH40钢样品表面微生物群落结构分析   27

2.3.5 潮差区EH40钢样品表面微生物群落结构分析   35

2.3.6 不同区域微生物群落对EH40钢腐蚀影响差异机制   43

2.4 本章小结     46

第3章 周期浸润对铜绿假单胞菌作用下EH40钢腐蚀的影响机制   47

3.1 引言     47

3.2 实验材料与方法 47

3.2.1 实验材料  47

3.2.2 实验试剂  47

3.2.3 腐蚀介质及实验设计      48

3.2.4 腐蚀速率表征  49

3.2.5 腐蚀形貌及腐蚀产物表征      49

3.2.6 生物膜及细菌数量表征  50

3.2.7 TEL表征    50

3.2.8 转录组测序      51

3.2.9 细菌ATP定量  51

3.2.10 吩嗪衍生物及相关基因的定量    51

3.3 实验结果与讨论 52

3.3.1 腐蚀速率分析  52

3.3.2 腐蚀形貌分析  57

3.3.3 腐蚀产物分析  59

3.3.4 TEL分析    60

3.3.5 生物膜和细胞计数分析  61

3.3.6 ATP及吩嗪衍生物的分析 63

3.3.7 转录组学响应分析  65

3.3.8 腐蚀机制  70

3.4 本章小结     72

第4章 周期浸润对泰坦尼克盐单胞菌作用下EH40钢腐蚀的影响机制   73

4.1 引言     73

4.2 实验材料与方法 73

4.2.1 实验材料  73

4.2.2 实验试剂  73

4.2.3 腐蚀介质及实验设计      74

4.2.4 腐蚀速率表征  74

4.2.5 腐蚀形貌及腐蚀产物表征      74

4.2.6 生物膜及细菌数量表征  74

4.2.7 转录组测序      74

4.2.8 TEL厚度及溶解氧表征    74

4.3 实验结果与讨论 75

4.3.1 腐蚀速率分析  75

4.3.2 腐蚀形貌分析  79

4.3.3 腐蚀产物分析  82

4.3.4 生物膜和细胞计数分析  83

4.3.5 转录组学响应分析  84

4.3.6 TEL分析    87

4.3.7 腐蚀机制  87

4.4 本章小结     89

第5章 水线环境下铜绿假单胞菌对EH40钢的腐蚀影响机制   90

5.1 引言     90

5.2 实验材料与方法 90

5.2.1 实验材料  90

5.2.2 实验试剂  90

5.2.3 腐蚀介质  90

5.2.4 阵列电极的制备及实验设计  90

5.2.5 电偶电流及腐蚀电位测试      91

5.2.6 自腐蚀线性极化电阻测试      91

5.3 实验结果与讨论 91

5.3.1 电偶电流面分布分析      91

5.3.2 腐蚀电位面分布分析      97

5.3.3 自腐蚀线性极化电阻分析      99

5.3.4 腐蚀机制  101

5.4 本章小结     102

第6章 水线环境下泰坦尼克盐单胞菌对EH40钢的腐蚀影响机制   103

6.1 引言     103

6.2 实验材料与方法 103

6.2.1 实验材料  103

6.2.2 实验试剂  103

6.2.3 腐蚀介质  103

6.2.4 阵列电极制备及实验设计      103

6.2.5 腐蚀电化学表征      104

6.2.6 腐蚀失重表征  105

6.2.7 腐蚀形貌及腐蚀产物表征      105

6.2.8 生物膜表征      105

6.3 实验结果与讨论 105

6.3.1 电偶电流面分布分析      105

6.3.2 腐蚀电位面分布分析      109

6.3.3 腐蚀电化学分析      113

6.3.4 失重分析  119

6.3.5 腐蚀形貌分析  119

6.3.6 生物膜形貌分析      122

6.3.7 腐蚀产物分析  122

6.3.8 腐蚀机制  123

6.4 本章小结     127

第7章 结论与展望  129

7.1 结论     129

7.2 创新点  130

7.3 展望     130

参考文献    133

致  谢 149

作者简历及攻读学位期间发表的学术论文与其他相关学术成果 150