Even after more than 20 years in the ocean, everyday plastics can show very few signs of breaking up or degrading, according to a new study examining the effects of deep-sea submersion on this problematic material.
Researchers looked at two plastic samples recovered from 4,150 metres (13,615 feet) below the surface of the eastern Pacific Ocean, finding that the majority of the plastic was still fully intact, and had also influenced microbial communities growing on the plastic surface.
While it isn't difficult to find plastic in the oceans, it can be difficult to accurately date it, so the findings serve as an important warning about just how long plastic can stick around once it's been dumped into the sea.
"The present study results represent, to our knowledge, the first data set reliably integrating the fate and ecological function of plastic over a time interval of more than two decades under natural marine deep-sea environmental conditions," write the researchers in their published paper.
A food container and a Coca-Cola can wrapped in a plastic bag were the discarded items recovered by the researchers, found among many others observed on the sea floor.
Thanks to a code and brand name on the container, and the fact the can was part of a limited edition run, the team was able to date the items to between 1988 and 1996.
While the aluminium of the Coca-Cola can would have ordinarily wasted away, the plastic bag did a very good job of preserving it – so much so that the can's label was still clearly visible. After recovering these two items, the scientists were able to run a chemical and bacterial analysis of the objects.
"It turned out that neither the bag nor the curd box showed signs of fragmentation or even degradation," says biogeochemist Stefan Krause from the GEOMAR research institute in Germany.
Even though the container and the bag were different shapes and were made from different types of plastics, their impact on the surrounding bacteria was the same, the scientists found – the microbial diversity was much lower on the plastic than in the surrounding seafloor sediments.
We already know that hazardous chemicals leach out from plastic submerged in water, and that may be what's happening here. The researchers do point out, however, that two plastic objects constitute a very small sample size, so further studies are going to be required here.
The team of scientists was actually in the area to investigate how mining manganese nodules from the seafloor might affect the ocean environment, so the accidental discovery of the plastic – and the fact that it could be so accurately dated – means we're lucky to have these findings at all, even if the results themselves are discouraging.
While work continues on dealing with our plastic problem – more than 60 percent of floating debris in the ocean is thought to be plastic – next up for the research team is a project looking in more detail at where the plastic dumped in the ocean actually ends up.
"This study builds also an important basis for our new project HOTMIC [Horizontal and Vertical Oceanic Distribution, Transport, and Impact of Microplastics], where we aim to trace the plastic waste entering the ocean from the continents to the large oceanic eddies and further to their final sink, the abyssal seafloor," says GEOMAR marine scientist Matthias Haeckel.
The research has been published in Scientific Reports.
Hata baada ya miaka 20 ya kutumiwa, plastiki ya kila siku inaweza kuonyesha dalili chache sana za kuvunjika au kuharibika, kulingana na utafiti mpya unaochunguza athari za kuzamishwa kwa bahari kwa nyenzo hii yenye shida. Watafiti walichunguza sampuli mbili za plastiki zilizopatikana mita 4,150 chini ya uso wa Bahari ya Pasifiki ya Mashariki na kugundua kwamba sehemu kubwa ya plastiki ilikuwa bado haijaharibika kabisa na pia ilikuwa imeathiri jamii za vijidudu vinavyoishi kwenye uso wa plastiki. Ingawa si vigumu kupata plastiki katika bahari, inaweza kuwa vigumu tarehe yake kwa usahihi, hivyo matokeo kutumika kama onyo muhimu kuhusu jinsi muda mrefu plastiki inaweza kukaa karibu mara moja ni kutupwa katika bahari. "Matokeo ya utafiti huu yanawakilisha, kwa maarifa yetu, seti ya kwanza ya data inayounganisha kwa kuaminika hatima na kazi ya ikolojia ya plastiki kwa muda wa zaidi ya miongo miwili chini ya hali ya asili ya mazingira ya bahari ya kina kirefu, ""waandishi wa utafiti waliandika." Chupa ya chakula na chupa ya Coca-Cola iliyozungukwa katika mfuko wa plastiki zilikuwa vitu vilivyotupwa na watafiti, vilivyopatikana miongoni mwa vitu vingine vingi vilivyogunduliwa kwenye sakafu ya bahari. Kwa sababu ya jina la bidhaa na nambari kwenye chombo hicho, na kwa sababu ya kuwa chombo hicho kilitengenezwa kwa kiasi kidogo, timu hiyo iliweza kugundua kwamba vitu hivyo vilitengenezwa kati ya mwaka wa 1988 na 1996. Wakati alumini ya Coca-Cola inaweza kuwa kawaida kupotea mbali, mfuko wa plastiki alifanya kazi nzuri sana ya kuhifadhi <unk> hivyo sana kwamba lebo ya unaweza bado ilikuwa wazi inayoonekana. Baada ya kupata vitu hivyo viwili, wanasayansi waliweza kuchanganua vitu hivyo kwa kemikali na bakteria. "Iligunduliwa kwamba mfuko huo wala sanduku la keki halikuwa na dalili za kugawanyika au hata kuharibika,"" anasema Stefan Krause, mtaalamu wa kemia ya kibiolojia kutoka taasisi ya utafiti ya GEOMAR nchini Ujerumani." Ingawa chombo hicho na mfuko huo ulikuwa na umbo tofauti na ulitengenezwa kwa aina tofauti za plastiki, athari zao kwa bakteria zilizozunguka zilikuwa sawa, wanasayansi walipata - utofauti wa vimelea ulikuwa chini sana kwenye plastiki kuliko katika matope ya chini ya bahari. "Kama tunavyojua, kemikali hatari hutoka kwenye plastiki iliyo ndani ya maji, na huenda ndivyo ilivyo hapa.""" Hata hivyo, watafiti wanasema kuwa vitu viwili vya plastiki ni sampuli ndogo sana, kwa hivyo utafiti zaidi utahitajika hapa. """Timu ya wanasayansi ilikuwa katika eneo hilo kuchunguza jinsi madini ya manganese nodules kutoka chini ya bahari inaweza kuathiri mazingira ya bahari, hivyo ugunduzi wa bahati mbaya wa plastiki na ukweli kwamba inaweza kuwa sahihi sana tarehe ina maana sisi ni bahati ya kuwa na matokeo haya hata kama matokeo yenyewe ni ya kukatisha tamaa." Wakati kazi inaendelea juu ya kushughulikia tatizo letu la plastiki - zaidi ya asilimia 60 ya takwimu za kuteleza katika bahari ni plastiki - inayofuata kwa timu ya utafiti ni mradi wa kuangalia kwa undani zaidi ambapo plastiki iliyotupwa baharini inakwenda. "Utafiti huu pia unajenga msingi muhimu kwa mradi wetu mpya wa HOTMIC (Ugawaji wa Bahari ya Upepo na Vertical, Usafiri, na Athari ya Microplastics), ambapo tunakusudia kufuatilia taka za plastiki zinazoingia baharini kutoka bara hadi mabwawa makubwa ya baharini na zaidi ya sinki yao ya mwisho, sakafu ya bahari ya abyssal. """ Utafiti huo umechapishwa katika jarida la Scientific Reports.