– MHWESG Presentation at Coastal Futures 2019

Long-term monitoring and surveillance programmes vary in their purpose, cost and complexity. But one thing they all have in common is the need to ensure comparability of data over time.

This basic, but often overlooked component to long-term studies, was the subject of a presentation given by Dr David Little, Environmental Consultant, at the Coastal Futures 2019 conference on behalf of the MHWESG.

Key messages from Dr Little’s presentation are:

• Lab methods change over time, meaning new data cannot always be compared directly with older datasets
• In order to produce a reliable baseline and timeline, intercalibration exercises are needed when the methods change
• For meaningful comparison of different datasets, the archive of results should embed field and lab methods, even where these are accredited
• Awareness of field and laboratory methods is particularly important when datasets are used to develop baselines, trends or EIAs

Dr Little’s most recent contribution to the MHWESG’s surveillance work was the development of a timeline for sediment contaminant concentrations in the Milford Haven Waterway. However this was not a straightforward task.

Incomparable laboratory methods since the 1960s required the organisation of an intercalibration exercise whereby samples were analysed using modern and older laboratory techniques. This ultimately enabled older data to be used in the development of a timeline for sediment contaminants going back to the late 1800s (via isotopic dating of deep cores in the 1980s).

The task of researching the varying laboratory methods used over the years was only possible due to Dr Little’s personal involvement with sediment contaminant work in the Milford Haven Waterway over previous decades.

Members of the MHWESG felt that this was an important message to communicate to others involved with long-term surveillance/monitoring programmes, and the Group are grateful to Dr Little for delivering these messages on their behalf.