title: Environmental Risk Implications of Metals in Sludges from Waste Water Treatment Plants: The Discovery of Vast Stores of Metal-Containing Nanoparticles.
abstract: Nanoparticle (NP) assessment in sludge materials, although of growing importance in eco- and biotoxicity studies, is commonly overlooked and, at best, understudied. In the present study, sewage sludge samples from across the mega-city of Shanghai, China were investigated for the first time using a sequential extraction method coupled with single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) to quantify the abundance of metal-containing NPs in the extraction fractions and transmission electron microscopy to specifically identify the nanophases present. In general, most sludges observed showed high concentrations of Cr, Cu, Cd, Ni, Zn, and Pb, exceeding the maximum permitted values in the national application standard of acid soil in China. NPs in these sludges contribute little to the volume and mass but account for about half of the total particle number. Based on electron microscopy techniques, various NPs were further identified, including Ti-, Fe-, Zn-, Sn-, and Pb-containing NPs. All NPs, ignored by traditional metal risk evaluation methods, were observed at a concentration of 107-1011particles/g within the bioavailable fraction of metals. These results indicate the underestimate or misestimation in evaluating the environmental risks of metals based on traditional sequential extraction methods. A new approach for the environmental risk assessment of metals, including NPs, is urgently needed.
authors.forename: Feiyun
authors.initials: F
authors.lastname: Tou
authors.forename: Yi
authors.identifier: http://orcid.org/0000-0002-6794-2241
authors.initials: Y
authors.lastname: Yang
authors.forename: Jingnan
authors.initials: J
authors.lastname: Feng
authors.forename: Zuoshun
authors.initials: Z
authors.lastname: Niu
authors.forename: Hui
authors.initials: H
authors.lastname: Pan
authors.forename: Yukun
authors.initials: Y
authors.lastname: Qin
authors.forename: Xingpan
authors.initials: X
authors.lastname: Guo
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, College of Environmental Science and Engineering, Tongji University , Shanghai 200092, China.
authors.forename: Xiangzhou
authors.initials: X
authors.lastname: Meng
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: The Center for NanoBioEarth, Department of Geosciences, Virginia Tech , Blacksburg, Virginia 24061, United States.|Geosciences Group, Energy and Environment Directorate, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
authors.forename: Michael F
authors.initials: MF
authors.lastname: Hochella
mesh_terms: D002681:China; D004784:Environmental Monitoring; D019216:Metals, Heavy; D053758:Nanoparticles; D012722:Sewage / Q000737:chemistry*; D062065:Wastewater; D014867:Water; D018508:Water Purification
chemical_list: D019216:Metals, Heavy; D012722:Sewage; D062065:Wastewater; D014867:Water