Marine Scotland Data - Metal concentrations in sediment: EIR release

Information requested

Information on the sampling methodology, i.e. how the sediment samples for these determinands [dry weight of cadmium, lead, and mercury in sediment] were collected, from what depth, how they were stored, and how they were tested in laboratory conditions to obtain the sediment metal values.

Response

The answer to your question is:

• Metals in sediment analysis is undertaken by the Marine Directorate as part of the requirements of the UK Clean Seas Environment Monitoring Programme (CSEMP). The UK Marine Monitoring and Assessment Strategy (UKMMAS) sets out the requirements for monitoring of the UK marine environment in order to meet policy drivers such as the UK Marine Strategy and the OSPAR Convention for the Protection of the NE Atlantic (OSPAR). The Marine Directorate collect sediment samples on their annual CSEMP cruises using a Day Grab. Sediment samples are analysed for contaminants, including metals (Cd, Hg, Pb, Cr, Mn, Fe, Cu, Zn, Ni, As, Al and Li). The full description of the sampling method is outlined in the attached standard operating procedure. Since 2017 the metals analysis has been contracted to Cefas, a total digest method (HF) is used, followed by analysis by ICPMS. Samples are stored frozen, then freeze dried and ball-milled before sending to Cefas for analysis. The data produced is submitted to the national Marine Environment Monitoring and Assessment National Database (MERMAN-Introduction to the MERMAN Database managed by BODC) by the Marine Directorate. This data has been used in national (Scottish Marine assessment 2020- Clean and safe | Scotland's Marine Assessment 2020) and international assessments (OSPAR Quality Status Report 2023- All Indicator Assessments - OSPAR-OAP (Prod))

• Analysis Method summary: 0.2g of ball-milled sediment sample are digested in a mixture of hydrofluoric acid (HF), nitric acid (HNO3) and HCl using enclosed vessel microwave digestion. A programmed temperature and pressure ramp is activated during the digestion. The excess of HF is then complexed by the addition of a saturated solution of boric acid. The resultant digest is made up to volume with nanopure water and further diluted prior to analysis by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry ICP-OES. The method is accredited to ISO/IEC 17025 by UKAS Quality assurance: Internal Quality Control: A procedural blank and a certified reference material (CRM PACS 3 and NWTH2) will undergo the same procedure for each batch of samples. External Quality Control: Cefas participates in the MS1 (trace metals in sediments) QUASIMEME proficiency scheme using the method described above. 
• I enclose a copy of the Standard Operating Procedure for the Collection of Sediment Samples, which gives further information on sediment depth sampled. However, an exception under Regulation 11(2) of the EIRs (personal information) applies to the Issued By field in the header. This is because it contains the name of a junior official and is personal data of a third party. Disclosing it would contravene the data protection principles in Article 5(1) of the General Data Protection Regulation and in section 34(1) of the Data Protection Act 2018. This exception is not subject to the ‘public interest test’, so we are not required to consider if the public interest in disclosing the information outweighs the public interest in applying the exception.

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FOI - 202400420610 - Information released - Annex A

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