Prior to manned underwater operations in conformance with NORSOK U-100

The NUI sampler fulfills the NORSOK U-100 requirement that states “if the sediment analysis is performed at the surface, a sampling technique that  allows the gas-tight seabed sampling to be brought to surface maintaining the content of possible contaminants, shall be applied”.

The sediment sampler consists of an  inner and an outer container. Three  samplers are installed in a sampler frame before being lowered to the seabed.  Sediment sample is collected with the inner container, which is then inserted into the outer container and dynamically sealed.  Any pressure built up is equalized by sampler volume expansion. At surface the samplers are removed from the frame and stored in a freezer (-20oC) until transport to  laboratory.

NUI has established a procedure for processing the sediment samples at the  laboratory. While still inside the sampler, volatile organic compounds (VOCs) in the sediment sample are off-gassed into a helium gas phase, and further  transferred onto adsorbent tubes.   Analysis of VOCs in adsorbent tubes is performed by thermal desorption and gas chromatography – mass spectrometry (ATD-GC-MS). In addition, the sediment sample can be analysed for other components such as metals and non volatile hydrocarbons. Other sampler applications are in connection with ship wreck, polluted harbors, industrial  areas and sediments near fish farms.  Our lab is easily accessible in Gravdal, Bergen.

Gas analyses from sediment samples include:

• Volatile Organic Compounds (VOC).

Other analyses from sediment samples include:

• Total hydrocarbon (C₁₀-C₄₀) in the sediment.
• Mercury (Hg) in the sediment.
• Hydrogen sulphide (H2S) in pore water.

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