Influence of biofilms growth on corrosion potential of metals immersed in seawater

Abstract

The changes of corrosion potential (E corr ) of metals immersed in seawater were investigated with electrochemical technology and epifluoresence microscopy. In natural seawater, changes of E corr were determined by the surface corrosion state of the metal. E corr of passive metals exposed to natural seawater shifted to noble direction for about 150 mV in one day and it didn't change in sterile seawater. The in-situ observation showed that biofilms settled on the surfaces of passive metals when E corr moved in noble direction. The bacteria number increased on the metal surface according to exponential law and it was in the same way with the ennoblement of E corr . The attachment of bacteria during the initial period played an important role in the ennoblement of E corr and it is believed that the carbohydrate and protein in the biofilm are reasons for this phenomenon. The double layer capacitance (C dl ) of passive metals decreased with time when immersed in natural seawater, while remained almost unchanged in sterile seawater. The increased thickness and reduced dielectric constant of C dl may be reasons.

Acid-volatile sulfide and simultaneously extracted metals in surface sediments of the southwestern coastal Laizhou Bay, Bohai Sea: Concentrations, spatial distributions and the indication of heavy metal pollution status

“…YHH3 YHH2 YHH1 GLH3 GLH2 GLH1 YHH-GLH ZMH2 ZMH1 ZM-YHH L1 L2 L3 L4 L5 MH6 MH5 XQH4 XQH3 XQH2 XQH1 K1 K2 K3 MH4 MH3 MH2 MH1 J1 J2 J3 J4 BLH3 BLH2 BLH1 I1 I2 I3 DH2 DH1 YH5 YH4 YH3 YH2 YH1 H1 H2 H3 WH3 WH2 WH1 JLH2 SEMs can be combined with AVS to reduce their toxicity; however, AVS of excessively high content is also harmful to aquatic organism. AVS is usually abundant in the organic-rich and reductive environment, because AVS is mainly formed by sulfate reduction in the process of the metabolism of SRB which are anaerobic bacteria (Myhr et al, 2002;Wang et al, 2004). The serious anoxic environment may lead to the death of benthic organisms and fish.…”

Assessment of sediment quality based on acid-volatile sulfide and simultaneously extracted metals in heavily industrialized area of Asaluyeh, Persian Gulf: concentrations, spatial distributions, and sediment bioavailability/toxicity

“…Heavy metals can be reacted with AVS to decrease their biotoxicity, although AVS of extremely high content is also detrimental to aquatic life (Li et al 2014a). AVS has often high values in the environment with reductive status and high organic matter, because AVS is mostly generated by sulfate reduction in the metabolism of SRB that are anaerobic bacteria (Myhr et al 2002;Wang et al 2004). Regarding former cases mentioned, the method of AVS-SEM is not singly sufficient; hence, we compared findings of this study with several sediment quality guidelines of different countries to target more efficient evaluation of sediment quality that attended in following section.…”

Applications of molecular biology and biotechnology in oil field microbial biodiversity research

“…Thus, the corrosion rate of steel can increase to 15 fold. Hence, the corrosion brought by SRB is one of the most important problems to be solved (Wang et al, 2004).…”