Wednesday, 27 April 2016

Sampling the Tidal Thames by boat!...by Debbie White

Les, Charlie, Claire and the Thames Guardian.
Our plan during FY 15/16 was to take samples along the whole length of the River Thames to look at the micro organic pollutants such as pharmaceuticals, veterinary drugs and personal care products in the river. Little did I know this would lead to such an adventure.

The Wallingford BGS office is very close to the Thames so we are very used to sampling the river, therefore sampling the source to about Teddington Lock wasn’t a problem. The biggest problem was the tidal part of the Thames, not just because the river is very wide and difficult to access due to the tides but also because it flows through the centre of London and out to the sea. So we turned to our friends in the Environment Agency (EA) for help and advice.

Many months ago in an EA office in Wallingford I had a meeting with representatives from the EA about the possibility of sampling the tidal part of the River Thames with help from their Estuarine and Coastal Monitoring and Assessment Service (ECMAS). They were very interested in our project and the data we would produce and I was put in touch with Paul Smith and Clare Miller from the ECMAS. Paul and Clare were also interested in our work as our data could be an interesting addition to their database. ECMAS collect monthly samples from the Tidal Thames for chemical and ecological monitoring under the Water Framework Directive (WFD) and Environmental Quality Standards Directive (EQSD) using the Briggs Marine Vessel Thames Guardian.

Serving up homemade fruit cake, the universal currency (L) and titrating and filtering samples in the floating lab. 
I was able to satisfy the criteria to be allowed to board Thames Guardian but not to work on the back deck as I ‘unfortunately’ didn’t have time to undergo sea safety certificate training (apparently you are chucked into the water fully clothed and have to get into a life raft). Clare was going to collect the samples for me.

After discussions about dates, times, tides, risk assessments and equipment I was told to report to Chatham Docks for a 5 am ‘lock-out’ on 4th February. Clare and I loaded my equipment the afternoon before and met Paul, who was also in the area, on the Wednesday evening for a chat and a meal before retiring to our hotels for the early start.

We were all on the boat and going through the lock at 5 am the next morning. Yes, 5 am is very early (and very dark) but for Clare and the crew (Charlie and Les) this is a usual feature of their month. To make the most of the tide the plan was to go down the Medway and up to the furthest point on the Thames before turning around and taking the samples on the ebb tide. This left us with a couple of hours of darkness before we picked up the local river pilot (so a quick snooze) then a few more hours to sort out equipment and see the sights of London from the River! It was fantastic privilege to see London from the river, and the knowledgeable and friendly crew and local pilot made the trip by pointing out the best spots to take pictures of St Paul's and the history of all the buildings and areas along the way. It was difficult to tear myself away from the knowledge these guys had but work had to be done!

It was challenging getting used to working on board the ship as I hadn’t expected how choppy it would be at times. Some titrations had to wait when we were in busy parts of the river as the wake of passing ferries made it difficult to measure an accurate volume of sample. I could imagine it was making filling a bottle a little difficult for Clare too!

River water was sampled from 1m below the surface using a peristaltic pump and the ingenuity of Les’ sample tube-on-a-stick, on which he had also marked the 1m point for ease of deployment.

The peristaltic pump before use (R) and in use by Clare (L)
Hydrochemical parameters such as pH, salinity and temperature were measured by the Idronaut Ocean Seven muliparameter probe deployed over the side of the vessel while we stopped to sample and the co-ordinates of the sample sites were fixed by the on-board GPS system. We settled into a routine on the way back down the river and collected 15 samples along the tidal stretch of the Thames and got back into Chatham dock at about 5 pm.

My thanks go to the team as without the help and good humour Clare Miller from the EA, Charlie and Les from Briggs Marine this sampling would not have been possible.

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