Anthropogenic Release and Distribution of Titanium Dioxide Particles in a River Downstream of a Nanomaterial Manufacturer Industrial Site

Several industries manufacture and process large quantities of engineered nanomaterials, thus increasing the potential for their environmental release during waste management and disposal. Herein, we quantified the release and spatial distribution of titanium dioxide nanomaterials (TiO2 NMs) emitted from an industrial waste stream that flows into a nearby river. Two sampling campaigns were carried out on the river in fall 2017 and spring 2018 at selected sites upstream and downstream of the Industrial Effluent and an urban wastewater treatment plant (WWTP). Significant Ti accumulation was detected in the sediments at the Industrial Effluent and WWTP sites for both fall and spring samples, with measured Ti concentrations of 75−193 mg Ti/kg reaching 21−55× that of the local background upstream. X-ray diffraction analysis confirmed the anatase and rutile mineralogy of the inputs. River surface waters were filtered on-site to distinguish between particulate (>0.20 μm), colloidal (0.02−0.20 μm), and dissolved and/or small nanoparticulate (NP) (0.20 µm), and that the particles sediment rapidly near the emission source and accumulate in the sediment.