Rivers of plas­tic bits

The Star Malaysia - Star2 - - ECOWATCH -

MIL­LIONS of tiny pieces of plas­tic are es­cap­ing waste­water treat­ment plant fil­ters and wind­ing up in rivers where they could po­ten­tially con­tam­i­nate drink­ing wa­ter sup­plies and en­ter the food sys­tem.

Mi­croplas­tics – small pieces of plas­tic less than 5mm wide – are an emerg­ing en­vi­ron­men­tal con­cern in seas, where they can harm marine an­i­mals. Al­though the ma­jor­ity of ocean de­bris – in­clud­ing plas­tics – is trans­ported to oceans from rivers, much less is known about how mi­croplas­tics are en­ter­ing rivers and af­fect­ing river ecosys­tems, ac­cord­ing to Ti­mothy Hoellein, an as­sis­tant pro­fes­sor at Loyola Univer­sity Chicago.

Fish and in­ver­te­brates eat the tiny pieces of plas­tic in rivers, which then make their way up the food chain – pos­si­bly end­ing up on our din­ner plates, he said. Like mi­croplas­tics in the ocean, plas­tics found in rivers carry po­ten­tially harm­ful bac­te­ria and other pol­lu­tants on their sur­faces.

Hoellein pre­vi­ously found that wa­ter down­stream from a waste­water treat­ment plant had a higher con­cen­tra­tion of mi­croplas­tics than wa­ter up­stream. His new re­search on 10 ur­ban rivers in Illinois sup­ports this ini­tial find­ing. Al­though ini­tial es­ti­mates sug­gest that waste­water treat­ment plants are catch­ing 90% or more of the mi­croplas­tics, the amount be­ing re­leased daily with treated waste­water into rivers is sig­nif­i­cant, rang­ing from 15,000 to 4.5 mil­lion mi­croplas­tic par­ti­cles per day per treat­ment plant.

Waste­water treat­ment plants were a source of mi­croplas­tics in 80% of the rivers stud­ied. The re­search also found the tiny plas­tic par­ti­cles to host bac­te­rial com­mu­ni­ties.

“Waste­water treat­ment plants do a great job of do­ing what they are de­signed to do, which is treat waste for ma­jor pathogens and re­move ex­cess chem­i­cals like car­bon and ni­tro­gen from the wa­ter that is re­leased back into the river,” Hoellein said. “But they weren’t de­signed to fil­ter out th­ese tiny par­ti­cles.”

The re­search also found that mi­croplas­tics not only stay in ecosys­tems for a long time, but travel a long way from their point of ori­gin – some as far as 2km down­stream.

This sup­ports the idea that rivers can trans­port plas­tic and pathogens over long dis­tances and even­tu­ally, in­tro­duced into var­i­ous ecosys­tems, Hoellein said. Sci­en­tists are also study­ing how much plas­tic stays in rivers and how much ends up in oceans to bet­ter un­der­stand the life­cyle of th­ese tiny pieces of plas­tics. – Amer­i­can Geo­phys­i­cal Union

A jar of sea­wa­ter with mi­croplas­tics. Most waste­water treat­ment plants are un­able to re­move th­ese tiny plas­tic bits. — ePA

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