Marine plastic waste has become a global environmental problem, and in order to solve it, it is necessary to clarify the dynamics of plastic waste in the watershed area of land, river, and sea.This time, a research group at Tokyo University of Science has developed a technology for measuring the amount of waste in rivers using image analysis, and succeeded in grasping the amount of large-sized plastic waste (macroplastic) in rivers.
Monitoring technology for how much plastic waste is transported from rivers to sea areas has been established to some extent for small-sized microplastics.However, with regard to macroplastics, although a method of directly collecting them using a net or the like can be considered, the work load is large and it has been desired to establish a more efficient technique.
The technology developed this time is to continuously photograph the surface of river water using a digital video camera, etc., identify drifting waste based on an image analysis method, and monitor the amount of transport.Observations were carried out in the Edo River and Ohori River in Chiba Prefecture based on this technology, and when compared with the verification data (results of direct garbage collection and visual garbage discrimination), it was found that the discrimination was performed with generally good accuracy. I was able to evaluate it.
Examination of the obtained macroplastic transport volume data revealed that macroplastics were transported intensively at the time of flooding.In addition, this technology made it possible for the first time in the world to simultaneously observe and compare macroplastics and microplastics, and it was found that the transport volume of macroplastics and microplastics was about the same on an annual basis.
It can be said that the implementation of plastic waste reduction measures is an urgent issue for the marine plastic waste problem.
