Sewage spills are a major source of titanium dioxide engineered (nano)-particles into the environment

Frederic Loosli; Jingjing Wang; Sarah Rothenberg; Michael Bizimis; Christopher Winkler; Olga Borovinskaya; Luca Flamigni; Mohammed Baalousha

doi:10.1039/C8EN01376D

Sewage spills are a major source of titanium dioxide engineered (nano)-particles into the environment

Environ Sci Nano. 2019 Mar 1;6(3):763-777. doi: 10.1039/C8EN01376D. Epub 2019 Jan 28.

Authors

Frederic Loosli¹, Jingjing Wang¹, Sarah Rothenberg², Michael Bizimis³, Christopher Winkler⁴, Olga Borovinskaya⁵, Luca Flamigni⁵, Mohammed Baalousha¹

Affiliations

¹ Department of Environmental Health Sciences, Center for Environmental Nanoscience and Risk, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, United States.
² School of Biological and Population Health Sciences, Oregon State University, Corvallis, Oregon, USA.
³ School of the Earth, Ocean, and Environment, University of South Carolina, Columbia, South Carolina, United States.
⁴ Virginia Tech National Center for Earth and Environmental Nanotechnology (NanoEarth), 1991 Kraft Dr, Blacksburg, VA24061, USA.
⁵ TOFWERK, Thun, Switzerland.

Abstract

Sanitary sewer overflows (SSOs) are a common problem across the United States. An estimated 23,000-75,000 SSOs occurred annually in 2004 discharging between 11 and 38 billion liters of untreated wastewater to receiving waters. SSOs release many contaminants, including engineered nanomaterials (ENMs), to receiving water bodies. Measuring ENM concentrations in environmental samples remains a key challenge in environmental nanotechnology and requires the distinction between natural and engineered particles. This distinction between natural and engineered particles is often hampered by the similarities in the intrinsic properties of natural and engineered particles such as particle size, composition, density, surface chemistry, and by the limitations of the available nanometrology tools. To overcome these challenges, we applied a multi-method approach to measure the concentrations and properties of TiO₂ engineered particles (e.g., ENMs and pigments) including 1) multi-element single particle-inductively coupled plasma-mass spectrometry (ME-SP-ICP-MS) to identify elemental associations and to determine elemental ratios in natural particles, 2) total elemental concentrations and ratios calculated from total metal concentrations measured following total sample digestion to estimate engineered particle concentrations, and 3) transmission electron microscopy (TEM) to characterize engineered particle size and morphology. ME-SP-ICP-MS analysis revealed that natural TiO₂ particles are often associated with at least one of the following elements Al, Fe, Ce, Si, La, Zr, Nb, Pb, Ba, Th, Ta, W and U, and that elemental ratios of Ti to these elements is typical of riverine particulates and the average crustal ratios, except for Pb likely due to anthropogenic Pb contamination. High TiO₂ engineered particle concentrations up to 100 μg L^-1 were found in SSOs-impacted surface waters. TEM analysis demonstrated the presence of regular-shape TiO₂ particles in SSOs-impacted surface waters. This study provides a comprehensive approach for measuring TiO₂ engineered particle concentrations in surface waters. The quantitative data produced in this work can be used as input for modeling studies and pave the road toward routine monitoring of ENMs in environmental systems, validation of ENM fate models, and more accurate ENM exposure and risk assessment.

Abstract

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