Polymers May Chemically Degrade In The Ocean

Little is known about the chemical decomposition of the many tons of plastic debris floating in the world’s ocean. Scientists have assumed that this trash physically degrades but remains chemically intact. That assumption may not be a good one, according to researchers in Japan. Katsuhiko Saido of Nihon University, in Chiba; Yoichi Kodera of the National Institute of Advanced Industrial Science & Technology, in Tsukuba; and coworkers analyzed sand and water samples from coastal areas around the world and found degradation products from a variety of polymers. To understand whether the polymers could produce such compounds under conditions similar to those in the ocean, the researchers performed laboratory studies of the thermal degradation of polymer mixtures over a wide temperature range. In those experiments, polystyrene released styrene monomers, dimers, and trimers at temperatures as low as 30 °C, which is similar to temperatures at the ocean surface. Such degradation is more likely to happen in the harsher environment near the coast than in the open ocean, Kodera said.