Plastic pollution of water is now a global problem that needs to be better understood, in order to find ways of 𝗺𝗶𝗲𝘂𝘅 𝗽𝗿𝗼𝘁𝗲́𝗴𝗲𝗿 𝗹𝗲𝘀 𝗲́𝗰𝗼𝘀𝘆𝘀𝘁𝗲̀𝗺𝗲𝘀 𝗮𝗾𝘂𝗮𝘁𝗶𝗾𝘂𝗲𝘀 𝗲𝘁 𝗻𝗼𝘁𝗿𝗲 𝘀𝗮𝗻𝘁𝗲́. Lake Geneva is no exception to this type of pollution.
This is why the ASL wanted to find out more and in 2018 commissioned Dr Julien Boucher, a specialist in this field, to carry out 𝘂𝗻𝗲 𝗺𝗼𝗱𝗲́𝗹𝗶𝘀𝗮𝘁𝗶𝗼𝗻 𝗱𝗲𝘀 𝗳𝗹𝘂𝘅 𝗱𝗲 𝗽𝗹𝗮𝘀𝘁𝗶𝗾𝘂𝗲𝘀 𝗱𝗮𝗻𝘀 𝗹𝗲 𝗹𝗮𝗰. The study, conducted in partnership with an EPFL team led by Luiz Felippe de Alencastro, identified 𝗹𝗲𝘀 𝘀𝗼𝘂𝗿𝗰𝗲𝘀 𝗺𝗮𝗷𝗲𝘂𝗿𝗲𝘀 𝗱𝗲𝘀 𝗳𝗹𝘂𝘅 𝗱𝗲 𝗽𝗹𝗮𝘀𝘁𝗶𝗾𝘂𝗲 : storm overflows, runoff and direct discharges would be 𝗽𝗿𝗶𝗻𝗰𝗶𝗽𝗮𝘂𝘅 𝗿𝗲𝘀𝗽𝗼𝗻𝘀𝗮𝗯𝗹𝗲𝘀.

Through these various means, 𝗲𝗻𝘃𝗶𝗿𝗼𝗻 𝟱𝟬 𝘁𝗼𝗻𝗻𝗲𝘀 𝗱𝗲 𝗽𝗹𝗮𝘀𝘁𝗶𝗾𝘂𝗲 𝗳𝗶𝗻𝗶𝘀𝘀𝗲𝗻𝘁 𝗱𝗮𝗻𝘀 𝗹𝗲 𝗟𝗲́𝗺𝗮𝗻 𝗰𝗵𝗮𝗾𝘂𝗲 𝗮𝗻𝗻𝗲́𝗲.
Only 10% of the plastics discharged into Lake Geneva would be carried downstream by the Rhône at Geneva. This would therefore mean that 𝗹𝗮 𝗽𝗹𝘂𝘀 𝗴𝗿𝗮𝗻𝗱𝗲 𝗽𝗮𝗿𝘁𝗶𝗲 𝗱𝗲𝘀 𝗽𝗹𝗮𝘀𝘁𝗶𝗾𝘂𝗲𝘀 arriving in lake 𝘆 𝘀𝗲𝗿𝗮𝗶𝘁 𝗽𝗶𝗲́𝗴𝗲́𝗲, the latter functioning as a settling basin.
This raises many questions about the fate and distribution of the plastics that 'stagnate' in Lake Geneva. 𝗜𝗹𝘀 𝘀𝗲 𝗿𝗲𝘁𝗿𝗼𝘂𝘃𝗲𝗻𝘁 𝗽𝗮𝗿𝘁𝗼𝘂𝘁, on the banks, on the surface of the water, at the bottom of the lake and in the sediment.
Due to physico-chemical phenomena in the aquatic environment, the larger plastic elements break up into smaller ones, which can go as far as 𝗷𝘂𝘀𝗾𝘂'𝗮̀ 𝗹'𝗲́𝗰𝗵𝗲𝗹𝗹𝗲 𝗱𝘂 𝗻𝗮𝗻𝗼𝗺𝗲̀𝘁𝗿𝗲!
𝗤𝘂𝗶𝗱 𝗱𝗲 𝗹𝗲𝘂𝗿𝘀 𝗶𝗺𝗽𝗮𝗰𝘁𝘀 𝘀𝘂𝗿 𝗹𝗮 𝗯𝗶𝗼𝗱𝗶𝘃𝗲𝗿𝘀𝗶𝘁𝗲́ 𝗹𝗮𝗰𝘂𝘀𝘁𝗿𝗲? Currently this is a question that is still difficult to answer. However, an EPFL study demonstrated in 2014 that 𝟭𝟬% 𝗱𝗲𝘀 𝗽𝗼𝗶𝘀𝘀𝗼𝗻𝘀 𝗱𝘂 𝗟𝗲́𝗺𝗮𝗻 𝗰𝗼𝗻𝘁𝗲𝗻𝗮𝗶𝘁 𝗱𝘂 𝗽𝗹𝗮𝘀𝘁𝗶𝗾𝘂𝗲 𝗱𝗮𝗻𝘀 𝗹𝗲𝘂𝗿 𝘁𝘂𝗯𝗲 𝗱𝗶𝗴𝗲𝘀𝘁𝗶𝗳, thus proving their presence in the lake food chain.
The effects on humans following the ingestion of these micro/nano-plastics are still poorly known, however, 𝗹𝗲 𝗽𝗿𝗶𝗻𝗰𝗶𝗽𝗲 𝗱𝗲 𝗽𝗿𝗲́𝗰𝗮𝘂𝘁𝗶𝗼𝗻 𝗱𝗲𝘃𝗿𝗮𝗶𝘁 𝗲̂𝘁𝗿𝗲 𝗮𝗱𝗼𝗽𝘁𝗲́ in order to put in place solutions 𝘃𝗶𝘀𝗮𝗻𝘁 𝗮̀ 𝗿𝗲́𝗱𝘂𝗶𝗿𝗲 𝗹𝗮 𝗽𝗼𝗹𝗹𝘂𝘁𝗶𝗼𝗻 𝗽𝗹𝗮𝘀𝘁𝗶𝗾𝘂𝗲 before the impact on health is known.
𝐒𝐨𝐮𝐫𝐜𝐞𝐬 :
– Lémanique n°110 "Lake Geneva is not a toy" 12/2018