Two months ago while meeting Kenyan manufacturers over the pollution chocking the Nairobi River, Environment, Climate Change and Forestry CS Aden Duale did not mince his words.
“I am here to pass a message, Nairobi River will be like River Thames in England, you will start drinking from it in 18 months because under President William Ruto we have a huge program and soon we will be installing cameras along that 47 kilometre stretch in a partnership with the Korean government that will help get a hold of those polluting the River and make them pay,” he said.
In the world over plastic pollution is an ever-growing problem as most societies have become overly dependent on plastics for packaging, medical supplies, and general goods.
This is because plastic litter accumulation in the ocean, either through deliberate dumping or by being transported from a river, poses significant environmental challenges.
Additionally, this plastic eventually degrades into small fragments called microplastics, which then impact diverse marine and land ecosystems by working their way up the food chain and into most living organisms.
Though their negative effects on cell health are still under study, many nations like Kenya have taken a cautionary stance, increasing efforts to curb plastic usage and prevent pollution.
As CS Duale works round the clock to make his dream a reality, scientists at the Tokyo University of Science(TUS) in Japan have published a peer-reviewed study in the journal Marine Global Journal that Kenya can perhaps borrow from as it embarks on cleaning her rivers, the Indian Ocean and other water bodies.
This is after a research team led by Assistant Professor Mamoru Tanaka of TUS decided to conduct the first nationwide-level analysis of plastic litter removal from rivers in Japan.
The researchers quantified the annual recovery of plastic waste from river banks and water surfaces using a dataset provided by the Ministry of Land, Infrastructure, Transport and Tourism in the country.
The dataset included the amount of plastic recovered from 109 river basins from 2016 to 2020.
The researchers analyzed this information and also investigated potential correlations with other factors, such as basin population, the extent of nearby urban areas, and topographical characteristics.
The total plastic recovery ranged from 763 to 1,177 tons/year, with an average of 938 tons/year.
“Given the emission estimates from previous studies, Japan’s annual plastic emissions are approximately 10,000-20,000 tons.
The plastic recovery in river basins of approximately 1,000 tons/year estimated in this study represents approximately one-tenth to one-twentieth of this total.
This is a non-negligible contribution toward reducing nationwide plastic emission, though not a decisive amount,” highlights Professor Tanaka.
As per their analysis, the top seven river systems by average plastic waste collection volume were the Yodo River system with 91.6 tons/year, the Yoshino River system with 85.8 tons/year, the Tone River system with 78.8 tons/year, the Tama River system with 72.0 tons/year, the Oto River system with 69.2 tons/year, and the Abukuma River system with 53.9 tons/year.
These accounted for roughly 50% of Japan’s total plastic collection volume.
By looking more closely at the data, the researchers noted that natural disasters and extreme weather events were closely related to spikes in the values of plastic litter collected from rivers.
“The Ota and Kiso River systems saw a significant rise in plastic waste collected in 2018. Both systems were affected by heavy rains in western Japan that year,” noted Tanaka, “Similarly, the Abukuma River system saw a rise in plastic collection in 2019, which can be attributed to the impact of Typhoon No. 19 in 2019, which caused substantial water damage,” their findings note.
They therefore concluded that the results shed some light on potential links between climate change, which leads to more extreme weather events, and plastic pollution.
The researchers then went ahead to look at other interesting correlations.
For example, the Yodo and Tone River systems, which saw some of the highest recovery rates, also serve over ten million people, but this also increases the amount of waste generated and leads to higher involvement from multiple municipalities.
Therefore, there is a positive correlation between the basin population, plastic litter recovery, and the number of people participating in cleanup activities.
“Currently, the Ministry of the Environment scientifically estimates plastic litter levels across various areas of Japan. Our estimates cover where and to what extent plastic waste is generated, how much is collected, how much is deposited in soil and riverbeds, and the amount discharged into the ocean, thereby providing key data to support these estimates,” said Professor Tanaka who holds a PhD in Applied Marine Environmental Studies from the Tokyo University of Marine Science and Technology and also focuses on observational physical oceanography, microplastics, hydraulic engineering, and turbulence.
“With any luck, this study will pave the way to better measures to achieve sustainable plastic management, reducing the devastating effects of plastic pollution on wildlife and public health,” he hopes.
