free floating devices to track and study litter in freshwater
They have been designed to simulate floating litter (e.g. the plastic bottle) in order to create mathematical models describing its behaviour in the environment.
The systems, which are sealed containers with a PET casing, can be kept in a "hibernation" condition using an external magnet. As well as directly tracking small litter floating in the current, if they are buried in the sediment of the embankments, they allow assessment of the erosion of the embankments, only waking up when they are released from the sands.
Small litter, with submergence profiles of just a few centimetres, follows the flow of the water and tends to run aground and accumulate in areas of shallower water and where the current is diminishing.
They tend to start up again when the water flow increases due to rainfall, seasons and/or the regulation of artificial hydraulic weirs.
Monitoring these phenomena is important for assessing the floating load that is displaced by the waters and ends up, if not otherwise intercepted, in the sea at river mouths.
The configuration can be changed remotely to allow monitoring of particular events.
Researchers can view the position of individual trackers and download historical position tables for import into their own data analysis systems.