Newly updated guidance for the UK’s risk-based approach (RBA) to the management of produced water discharges from offshore installations has been published. The updated guidance document, which recommends the use of NCIMB’s MARA and LumiMARA tests for marine toxicity testing, in preference to the more conventional Microtox bacteria test, was published by the UK Department for Business, Energy & Industrial Strategy in December.
The UK is implementing a risk-based approach to the management of produced water discharges from offshore oil and gas installations in accordance with the OSPAR Convention. OSPAR is the organisation that oversees international cooperation for the protection of the marine environment of the North East Atlantic, and the UK is a contracting party to the OSPAR Convention.
A risk-based approach includes assessment of the toxicity of the whole effluent, rather than focusing solely on the measurement of compounds within the effluent that are known be persistent, bioaccumulative and toxic. Produced water is a highly complex substance and this approach takes account of the impact of unknown substances within it, as well as the combined effects of all components of the produced water.
In practical terms this involves undertaking toxicity testing for at least three trophic levels such as bacteria, algae and crustacea.
NCIMB’s MARA and LumiMARA tests were recommended in preference to single species bacteria tests following successful trials with produced water samples from 15 offshore facilities in the North Sea. Samples used in the trial included a mixture of oil and gas producers as well as early and late stages of production, and high and low water cuts.
NCIMB’s Analytical Services Manager Michelle Robertson said: “A key element of a risk-based approach is assessment of the sensitivity of the receiving environment to potentially toxic substances. In practical terms this generally involves toxicity testing with single species from three different categories of living things such as bacteria, algae and crustaceans. MARA and LumiMARA together include 21 different species of microorganisms, and so substituting a single species bacterial test, such as Microtox, with MARA and LumiMARA is a very easy way to increase the total number of species included in toxicity testing from 3 to 23.
“Although they are invisible to the naked eye, it has been estimated that microorganisms account for 90% by weight of all living things in the ocean. Microbes are also much more genetically diverse than many people might realise. However, their small size and rapid response to toxicants also makes it easier to include greater microbial diversity in toxicity testing than with higher order organisms, and MARA and LumiMARA were developed to facilitate this.”
For more information about MARA and LumiMARA testing contact email@example.com The updated RBA guidance document can be found at https://www.gov.uk/guidance/oil-and-gas-environmental-policy