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Pristine Lakes Are Filled With Toxins (bbc.com)
Much of the focus on plastic pollution centres on our oceans. Emerging evidence shows it's also a problem in freshwater, which may even be the source. From a report: "Freshwater systems are increasingly studied but still at a much smaller scale than oceans," says Filella. This may simple be due to the fact that initial studies focused on the ocean -- and so research proposals and grants followed suit. It didn't take long for the Geneva team to find what they were looking for. Filella and colleagues collected over 3,000 samples. They went on to analyse 670 of these, revealing some worrying results. Many of these samples contained hazardous and toxic elements including cadmium, mercury and lead -- in some cases in "very high concentrations", as outlined in a 2018 paper in the journal Frontiers of Environmental Science.
A large proportion of these toxic elements are now banned or restricted. This "reflected the age and residence time of the plastic stock in the lake," says Filella: the plastic waste has been building up over several decades. And as we know, plastic can take hundreds of years to degrade. [...] Lake Geneva is not an outlier. Other lakes show similar levels of pollution. Italy's Lake Garda, for example, also has high levels of plastic waste. A sample from the northern part of the lake contained 1,000 large plastic particles and 450 smaller particles (microplastics) per square metre. [...] It is now becoming clearer that much of the plastic that ends up in the ocean starts off in freshwater bodies in the first place -- estimates suggest it could be as much as 70-80%.
A large proportion of these toxic elements are now banned or restricted. This "reflected the age and residence time of the plastic stock in the lake," says Filella: the plastic waste has been building up over several decades. And as we know, plastic can take hundreds of years to degrade. [...] Lake Geneva is not an outlier. Other lakes show similar levels of pollution. Italy's Lake Garda, for example, also has high levels of plastic waste. A sample from the northern part of the lake contained 1,000 large plastic particles and 450 smaller particles (microplastics) per square metre. [...] It is now becoming clearer that much of the plastic that ends up in the ocean starts off in freshwater bodies in the first place -- estimates suggest it could be as much as 70-80%.
I was confused by the summary too, so I looked at the study. These heavy metals used to be used in plastics as stabilizers and colour pigments, but are now typically banned. The study used this fact to demonstrate that the plastics they were finding predate regulations (i.e. are old) and have therefore been building up in these lakes for decades.