Sorry I didn't see this when you posted but here are stories I found on the topic, the news doesn't cover concentration but does mention they found plastic in a

Sorry I didn't see this when you posted but here are stories I found on the topic, the news doesn't cover concentration but does mention they found plastic in a higher percentage of samples versus earlier years surveys did not find nearly that much: https://www.nationalgeographic.com/environment/2019/02/deep-sea-creatures-mariana-trench-eat-plastic/ https://www.nationalgeographic.com/environment/2019/02/deep-... source article: https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.180667 https://royalsocietypublishing.org/doi/pdf/10.1098/rsos.1806... I distinctly remember reading the researchers made sure their probes and sensors were plastic free somehow before they sampled the digestive systems.