10.1021/es304016u.s001 Fabienne Schwab Fabienne Schwab Thomas D. Bucheli Thomas D. Bucheli Louise Camenzuli Louise Camenzuli Arnaud Magrez Arnaud Magrez Katja Knauer Katja Knauer Laura Sigg Laura Sigg Bernd Nowack Bernd Nowack Diuron Sorbed to Carbon Nanotubes Exhibits Enhanced Toxicity to Chlorella vulgaris American Chemical Society 2013 presence soot photosynthetic activity alga Chlorella vulgaris 5. Sorbed diuron results point carbonaceous nanoparticles diuron maximally Carbon Nanotubes Exhibits Enhanced Toxicity multiwalled CNT diuron concentration 24 h exposure exposure concentration algal cells herbicide diuron Diuron Sorbed diuron toxicity Chlorella vulgarisCarbon nanotubes LEEC diuron concentrations 2013-07-02 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Diuron_Sorbed_to_Carbon_Nanotubes_Exhibits_Enhanced_Toxicity_to_Chlorella_vulgaris/2400415 Carbon nanotubes (CNT) are more and more likely to be present in the environment, where they will associate with organic micropollutants due to strong sorption. The toxic effects of these CNT-micropollutant mixtures on aquatic organisms are poorly characterized. Here, we systematically quantified the effects of the herbicide diuron on the photosynthetic activity of the green alga Chlorella vulgaris in presence of different multiwalled CNT (industrial, purified, pristine, and oxidized) or soot. The presence of carbonaceous nanoparticles reduced the adverse effect of diuron maximally by <78% (industrial CNT) and <34% (soot) at 10.0 mg CNT/L, 5.0 mg soot/L, and diuron concentrations in the range 0.73–2990 μg/L. However, taking into account the measured dissolved instead of the nominal diuron concentration, the toxic effect of diuron was equal to or stronger in the presence of CNT by a factor of up to 5. Sorbed diuron consequently remained partially bioavailable. The most pronounced increase in toxicity occurred after a 24 h exposure of algae and CNT. All results point to locally elevated exposure concentration (LEEC) in the proximity of algal cells associated with CNT as the cause for the increase in diuron toxicity.