Page 58 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Chapter 3. Metal corrosion protection potential of methanogenic communities Materials and methods
Sample collection and physicochemical analysis
The pumping station of Gouderak (Zuid-Holland, the Netherlands, 51° 59' 1.233" N, 4° 40' 20.654" E) was constructed in 1866 and is used for land drainage. It removes water from the Stolwijksche Boezem into the river Hollandse IJssel. Sheet piles that were installed 50 years ago were pulled out of the ground on 31 May 2012 and 6 June 2012 for renovation work on the pumping station and its surroundings. The sheet piles were 5-6 m long and driven up to 4 m into the sediment. The part exposed to the atmosphere was occasionally submerged at high tide. The belowground part of the sheet pile did not show any signs of corrosion. However, different deposit layers were visible at various depths (Fig. 1). Samples were taken from the sheet pile directly after extraction.
AB
DL Metal
Figure 1. A) Picture of sediment and deposit layers visible on a sheet pile sampled at the pumping station of Gouderak. B) Picture of deposit layer at Rotterdam Harbor sheet piles after careful removal of sediment layers. Pictures were taken by N.K.
Sediment samples were taken from the top layer (bulk sediment [BS]) and at three meters depth surrounding the sheet pile, at most 5 cm from the sheet pile (adjacent sediment [AS]) (Fig. 2). Deposit layers were sampled as aseptically as possible and, where possible, layers were scraped off. Samples taken on 31 May were immediately stored under anoxic conditions, transported on ice, and stored at -20°C. Samples from 6 June were stored at -20°C after transport. See Table S3 in the supplemental material for additional sample information.
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