Horizon 1 1 17 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES Environmental Science and Technology 6989-6998 engineered nanomaterials environmental conditions aging copper nanoparticles marine phytoplankton ecotoxicity 2023 fdi:010087714 ENG Environmental Science and Technology 0013-936X ISI:000982557500001 17 10.1021/acs.est.2c07953 https://www.documentation.ird.fr/hor/fdi:010087714 https://www.documentation.ird.fr/intranet/publi/2023-06/010087714.pdf 57 Horizon (IRD) Environmental conditions in aquatic ecosystems transform toxic chemicals over time, influencing their bioavailability and toxicity. Using an environmentally relevant methodology, we tested how exposure to seawater for 1-15 weeks influenced the accumulation and toxicity of copper nanoparticles (nano-Cu) in a marine phytoplankton species. Nano-Cu rapidly agglomerated in seawater and then decreased in size due to Cu dissolution. Dissolution rates declined during weeks 1-4 and remained low until 15 weeks, when the large agglomerates that had formed began to rapidly dissolve again. Marine phytoplankton species were exposed for 5-day periods to nano-Cu aged from 1 to 15 weeks at concentrations from 0.01 to 20 ppm. Toxicity to phytoplankton, measured as change in population growth rate, decreased significantly with particle aging from 0 to 4 weeks but increased substantially in the 15-week treatment due apparently to elevated Cu dissolution of reagglomerated particles. Results indicate that the transformation, fate, and toxicity of nano-Cu in marine ecosystems are influenced by a highly dynamic physicochemical aging process. 038 ; 021 ; 034 UR250