Center for Environmental Nanoscience and Risk, Department of Environmental Health Sciences, Arnold School of Public Health, University of South Carolina, Columbia, SC, United States.
Department of Civil and Environmental Engineering, University of California Los Angeles, California, USA.
Chemosphere. 2020 Jun;248:126070. doi: 10.1016/j.chemosphere.2020.126070. Epub 2020 Feb 1.
Urban runoff conveys contaminants including titanium dioxide (TiO), widely used as engineered nanoparticles (e.g., 1-100 nm) and pigments (e.g., 100-300 nm) in the urban environment, to receiving surface waters. Yet, the concentrations of TiO engineered particles (e.g., engineered nanoparticles and pigments) in urban runoff has not been determined due to difficulties in distinguishing natural from engineered TiO particles in environmental matrices. The present study examines the occurrence and estimates the concentrations of TiO engineered particles in urban runoff under wet- and dry-weather conditions. Urban runoff was collected from two bridges in Columbia, South Carolina, USA under wet-weather conditions and from the Ballona Creek and Los Angeles (LA) River in Los Angeles, California, USA under dry-weather conditions. The concentrations of TiO engineered particles were determined by mass balance calculations based on shifts in elemental concentration ratios in urban runoff relative to natural background elemental ratios. Elemental ratios of Ti to Nb in urban runoff were higher than the natural background ratios, indicating Ti contamination. The occurrence of TiO engineered particles was further confirmed by transmission electron microscopy coupled with energy dispersive spectroscopy. The concentration of TiO engineered particles in urban runoff was estimated to be in the range of 5-150 μg L. Therefore, this study identifies urban runoff as a previously unaccounted source of TiO engineered particle release to the environment, which should be included in engineered nanoparticle fate modeling studies and in estimating environmental release of engineered nanoparticles.
城市径流携带着污染物，包括在城市环境中广泛用作工程纳米粒子（例如，1-100nm）和颜料（例如，100-300nm）的二氧化钛（TiO），输送到受纳地表水中。然而，由于在环境基质中难以区分天然和工程 TiO 颗粒，因此尚未确定城市径流中 TiO 工程颗粒（例如工程纳米粒子和颜料）的浓度。本研究考察了在湿天和干天条件下城市径流中 TiO 工程颗粒的出现情况并估计了其浓度。在美国南卡罗来纳州哥伦比亚的两座桥上收集了湿天条件下的城市径流，并在美国加利福尼亚州洛杉矶的 Ballona Creek 和 Los Angeles（LA）河收集了干天条件下的城市径流。通过基于城市径流中元素浓度比相对于天然背景元素比的变化的质量平衡计算来确定 TiO 工程颗粒的浓度。城市径流中 Ti 与 Nb 的元素比高于天然背景比，表明存在 Ti 污染。TiO 工程颗粒的存在通过与能量色散光谱相结合的透射电子显微镜进一步得到证实。城市径流中 TiO 工程颗粒的浓度估计在 5-150μg/L 的范围内。因此，本研究确定城市径流是 TiO 工程颗粒释放到环境中的一个以前未被计算的来源，这应该被纳入工程纳米颗粒命运模型研究中，并用于估计工程纳米颗粒的环境释放。
