Potemkin Villages: the voyage to the sea for Kanagawa’s microplastics

 

In my post for June 17th last year, I told you I was depressed during beachcombing in Shonan Beach 湘南海岸 to find lots of lots of microplastics. For those colorful artificial bits to reach there, there must be something carrying them to that point. It’s river, yeah. There are not many research done for the matter. But Prof. Yasuo Nihei of Tokyo University of Science is receiving grant from the City of Kawasaki (and the others) for checking microplastic contamination in Tama, Tsurumi and Sagami (and the other) rivers. The other day, he did a small seminar reporting his findings. He told us very curious results.

Obvious garbage in the beach. They are macroplastics.

According to him, Japan is floating in the area that is the most contaminated by microplastics on this planet. Hmmmmmm. He said in 2015’s study (Isobe et al, 2015) sea around our archipelago contains on average 3.74 bits of microplastics per 1 cubic meter water. From his study, average number of microplastic particles found from his sample rivers was 4.3 per 1 cubic meter. That could mean the major source of oceanic contamination around Japan would be Japanese rivers starting from Japanese forest. He also noticed when a basin for one river has higher population density and urbanization, the number of microplastic fleck found from the river is larger. Er, well, it stands to reason ... So, inevitably Tama and Tsurumi Rivers scores “not so well” regarding the level of contamination.

Could you figure out plastics out of these?
Microplastics are defined as 5mm or less in its size.

It’s disheartening news. During the 1960s and the 1970s, Tsurumi River was a poster child of Japanese river pollution. It was a flow of stinking sludge. No one wanted to go near. So, people built lots of sewage treatment plants along the river. It makes Tsurumi River without smell of transparent stream. Yeah, unfortunately from Tsurumi River Japanese fluvial sculpin (Cottus pollux Gunther, Japanese endemic freshwater fish) has not been found these 60 years. Maybe they were extinct there. But migratory fishes that love clean water, like Ayu sweet fish and eels, are now spotted frequently. Kids and families enjoy relaxing picnic along the bank of the river. Then, in seemingly transparent water, micro and nano plastics are floating in the worst density of the planet. *Sigh* Not only that, Prof. Nihei’s team found another curious thing.

Admitting, it’s not rare finding
plastic trash on river banks of
Tsurumi River …

According to Prof. Nihei, the density of microplastics are higher both in Tama and Tsurumi Rivers near fashionable Misashikosugui 武蔵小杉. In the same Kawasaki City, the area near Kurokawa Forest 黒川の森 (my post on December 2, 2022) where Tsurumi River nearing to its source, the contamination is negligible. That’s a sort of solace. Then, researchers analyzed the source material of microplastics. The things they have identified were (1) plastic fibers, (2) astroturf, (3) styrofoam, and (4) tarpaulin. Which do you think was the most common? Astroturf.

A spring pond in Kurokawa Forest,
one of the sources for Tsurumi River

The team also did the same research in Hikichi River 引地川 that runs through the middle of the Cities of Yamato 大和 and Fujisawa 藤沢 from Izumi Forest 泉の森 of Yamato City. Among the 4 rivers, Tama, Tsurumi, Sagami, and Hikichi Rivers which run within / along Kanagawa Prefecture, the most contaminated with microplastics was Hikichi River. And its source of contamination was definitely astroturf. Why? The area for Hikichi River is a typical suburb of megalopolis Tokyo. The place has lots of detached houses and small driving ranges for golfers. It is the area for dwindling Japanese middle classes. Maybe, just maybe I mean, people cut corners for their small garden and employ astroturf that does not need human maintenance, but look pretty all year round. Ditto for ordinary golfers who do not want to spend money at Hodogaya Country Club (which is the most prestigious golf club in Japan; my post on July 24, 2015). Such beautification contaminates the land, river, and the ocean ... It might be a parable from Japan where population is shrinking with Potemkin suburbs ...

If you find environmental issues in Kanagawa Prefecture, please make a contact with Kanagawa Natural Environment Conservation Center 神奈川県自然環境保全センター

657 Nanasawa, Atsugi City, 243-0121
〒243－0121　厚木市七沢657
Phone: 046-248-0323

You can send an enquiry to them by clicking the bottom line of their homepage at http://www.pref.kanagawa.jp/div/1644/