Nav: Home

A radar for plastic: High-resolution map of 1 kilometre grids to track plastic emissions in seas

May 07, 2020

Plastic may be an indispensable part of our daily lives, but its robustness and abundance have led to its overuse, putting a huge burden on the environment. Large emissions of plastic waste result in its accumulation in water bodies: in fact, recent studies have estimated about 0.27 million tons of plastic floating in the world's oceans. Because plastic does not decompose in water, it is a serious hazard for the marine life. Thus, to prevent plastic pollution, it is crucial to understand exactly how plastic is emitted into the oceans. Previous studies have tried to analyze plastic emissions, but they had some limitations: they focused on mostly mismanaged plastic waste and not how these plastic emissions actually originate.

To this end, a group of scientists at the Tokyo University of Science, led by Prof Yasuo Nihei, developed a new method to combat plastic emissions. In a study published in Water, they generated a "high-resolution map of 1 km grids of plastic emissions across Japan. Prof Nihei explains, "If plastic waste continues to flow into the sea, the amount of plastic waste will increase. To prevent this, it is necessary to clearly indicate where and how plastic debris is currently being generated."

To begin with, the scientists focused on the different types of plastics: microplastic (MicP), which is less than 5 mm in size, and macroplastic (MacP), which is greater than 5 mm. They understood that controlling MicP was crucial because--owing to its small size--it is particularly hard to recover once it enters the ocean. Moreover, it can easily be ingested by marine organisms, which can negatively affect ecosystems worldwide. To avoid the emission of MicP in water bodies, it was important to find out exactly where these emissions were coming from.

The scientists followed a three-step process to map plastic emissions (Figure 1). First, they measured MicP concentration across 70 rivers and 90 sites in Japan and examined the relation between MicP concentration and land characteristics. They collected the ratio of MacP/MicP concentrations to evaluate the MacP concentration from the MicP concentration. Next, to obtain outflow discharge at 1 km grids, they performed a "water balance analysis" in which they measured precipitation of water, distributed into three categories: evaporation, surface runoff, and underground infiltration. Finally, they calculate total plastic emission, which is the product of MicP and MacP concentrations and outflow discharge. Their findings revealed that MicP concentrations and basin characteristics were significantly correlated, meaning that the physical features of water bodies dictate the amount of plastic waste accumulated. Not just this, their analysis helped the scientists to estimate the annual plastic emission in Japan, which ranged from 210 to 4,776 tons/year of total plastic.

The scientists then evaluated a high-resolution map of plastic emission over 1 km grids across Japan (Figure 2). They identified the critical areas where plastic emissions were the highest. Their analysis showed that these emissions were high in rivers near urbanized areas, with a high population density. Among these, cities like Tokyo, Nagoya, and Osaka were found to be hotspots for plastic emissions. Thus, this method was useful in understanding exactly where strict countermeasures should be enforced.

Unlike previous studies, this study does not assume that the plastic waste is only proportional to mismanaged plastic waste but, in fact, takes into account the origin of plastic emissions. This makes it easier to implement measures and curb plastic emissions in specific areas. Prof Nihei concludes, "Our findings provide new insights that may be used to draft countermeasures against plastic emissions, thereby reducing outflow of marine pollutants from Japan. We also introduce a new method that can be used to evaluate plastic inputs in other regions of the world."
-end-
About The Tokyo University of Science

Tokyo University of Science (TUS) is a well-known and respected university, and the largest science-specialized private research university in Japan, with four campuses in central Tokyo and its suburbs and in Hokkaido. Established in 1881, the university has continually contributed to Japan's development in science through inculcating the love for science in researchers, technicians, and educators.

With a mission of "Creating science and technology for the harmonious development of nature, human beings, and society", TUS has undertaken a wide range of research from basic to applied science. TUS has embraced a multidisciplinary approach to research and undertaken intensive study in some of today's most vital fields. TUS is a meritocracy where the best in science is recognized and nurtured. It is the only private university in Japan that has produced a Nobel Prize winner and the only private university in Asia to produce Nobel Prize winners within the natural sciences field.

Website: https://www.tus.ac.jp/en/mediarelations/

About Professor Yasuo Nihei from Tokyo University of Science

Dr Yasuo Nihei is a Professor in the Department of Civil Engineering, Tokyo University of Science. After completing his graduation at Tokyo Institute of Technology, he has now been working at Tokyo University of Science since 2000. A respected and senior researcher, his research interests include hydraulic engineering, with a focus on computational fluid mechanics and environmental hydraulics. He is the corresponding author of this paper and has over 170 research publications and 3 patents to his credit.

Funding information

This research was supported by the Japan Society for the Promotion of Science under the KAKENHI program (grant no. 17H04937), the River Fund of the River Foundation (grant no. 2019-5211-050), and the Tokyo University of Science Grant for President's Research Promotion.

Tokyo University of Science

Related Emissions Articles:

Tracking fossil fuel emissions with carbon-14
Researchers from NOAA and the University of Colorado have devised a breakthrough method for estimating national emissions of carbon dioxide from fossil fuels using ambient air samples and a well-known isotope of carbon that scientists have relied on for decades to date archaeological sites.
COVID-19 puts brakes on global emissions
Carbon dioxide emissions from fossil fuel sources reached a maximum daily decline of 17 per cent in April as a result of drastic decline in energy demand that have occurred during the COVID-19 pandemic.
Egregious emissions
Call them 'super polluters' -- the handful of industrial facilities that emit unusually high levels of toxic chemical pollution year after year.
Continued CO2 emissions will impair cognition
New CU Boulder research finds that an anticipated rise in carbon dioxide concentrations in our indoor living and working spaces by the year 2100 could lead to impaired human cognition.
Major new study charts course to net zero industrial emissions
A major new study by an interdisciplinary team of researchers finds that it is possible -- and critical -- to bring industrial greenhouse gas emissions to net zero by 2070.
Capturing CO2 from trucks and reducing their emissions by 90%
Researchers at EPFL have patented a new concept that could cut trucks' CO2 emissions by almost 90%.
Big trucks, little emissions
Researchers reveal a new integrated, cost-efficient way of converting ethanol for fuel blends that can reduce greenhouse gas emissions.
Uncertainty in emissions estimates in the spotlight
National or other emissions inventories of greenhouse gases that are used to develop strategies and track progress in terms of emissions reductions for climate mitigation contain a certain amount of uncertainty, which inevitably has an impact on the decisions they inform.
How buildings can cut 80% of their carbon emissions by 2050
Energy use in buildings -- from heating and cooling your home to keeping the lights on in the office -- is responsible for over one-third of all carbon dioxide (CO2) emissions in the United States.
Fracking likely to result in high emissions
Natural gas releases fewer greenhouse gases than other fossil fuels.
More Emissions News and Emissions Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.