Sullied Sediments volunteers adding to our growing evidence base
Over the last few months, volunteers from the Canal and River Trust’s Towpath Taskforce and Pocklington Canal Amenity Society have been busy carrying out sampling activities in the Humber Catchment (UK) and testing our measuring devices in the field. We now have some results to share via an open source map.
Over the last two years, our University of Hull PhD student, Samantha Richardson, has been developing and testing paper analytic devices, or PADs, in the lab. These PADs have various compounds embedded within them, which means they go blue when they come into contact with phosphates. When submerged in a water sample, the PAD can be used to test for the presence of phosphate and the level at which it was found.
While this work has been underway, we have also worked with an app developer to create a bespoke mobile app called RiverDip, which allows our volunteers to record the results from their PADs and share them with us. The app is downloadable from the iTunes and PlayStore.
It is important for users of the PADs to understand that phosphate is an essential nutrient needed by everyone in small amounts. However, if too much phosphate is present in the waterways, algae quickly grows on the surface of the water, blocking out sunlight and reducing plant growth below the surface.
And so onto our results… Below is a link to a map which shows where our diligent volunteers have been using our PADs:
In order to understand the results, please note the following key information:
We use five different categories on our map to show the results from the sampling: none, low, medium and high. We also show measurements that failed for one reason or another.
Many of the results we have received indicate low levels of phosphate or levels below what we can measure (shown as none on the map). We do see some areas where medium or high levels of phosphate are detected too. More often than not, these higher levels occur when sediment has been disturbed. The reason for this is because phosphate sticks to the sediment and can then get trapped for a long time. However, if the phosphate hasn’t bonded very tightly to the sediment, the phosphate comes off once disturbed and goes back into the water giving a temporary area of high phosphate concentration.
On our map we also show a number of ‘failed devices’: these are tests that have not yielded any useful results. This can occur for a number of reasons, for example water may not have been able enter the PAD, a shadow across the image could distort the image analysis or the image could be obstructed by debris in the sample. In developing anything new we always find problems but we can learn from these as we develop the sampling further. That’s all part of research!
If you would like to get involved in any our sampling activities please contact Annabel Hanson at email@example.com.