Silver near municipal wastewater discharges into western Lake Ontario, Canada

• Published in: Environmental monitoring and assessment Vol. 190; no. 9; pp. 555 - 12
• Main Authors: Metcalfe, Chris D., Sultana, Tamanna, Martin, Jonathan, Newman, Karla, Helm, Paul, Kleywegt, Sonya, Shen, Li, Yargeau, Viviane
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.09.2018; Springer Nature B.V
• Subjects: Agitation; Aquatic environment; Atmospheric Protection/Air Quality Control/Air Pollution; Bottom sediments; Carbon nanotubes; Cities; Detection; Detection limits; Discharge; Earth and Environmental Science; Ecology; Ecotoxicology; Environment; Environmental Management; Environmental monitoring; Environmental Monitoring - methods; Environmental science; Geologic Sediments - chemistry; Laboratory experiments; Lakes; Lakes - chemistry; Liquid phases; Local Government; Metal Nanoparticles - analysis; Monitoring/Environmental Analysis; Municipal wastewater; Nanoparticles; Nanotubes; Nanotubes, Carbon; Natural waters; Ontario; Samplers; Sediment; Sediments; Silver; Silver - analysis; Suspended sediments; Thin films; Waste Disposal, Fluid - methods; Waste Water - chemistry; Wastewater; Wastewater discharges; Wastewater treatment; Wastewater treatment plants; Water column; Water Pollutants, Chemical - analysis; Water pollution; Water treatment; Water treatment plants; Canada; Lake Ontario; Passive sampler; Silver; Single-particle ICP-MS; Nanosilver; Sediments; Wastewater
• ISSN: 0167-6369; 1573-2959
• DOI: 10.1007/s10661-018-6922-x

Because of the widespread use of silver nanoparticles in commercial products, discharges of municipal wastewater may be a point source of silver in the aquatic environment. We monitored two sites in western Lake Ontario impacted by discharges from wastewater treatment plants serving the City of Toronto. Concentrations of silver were elevated in bottom sediments and suspended sediments collected at the two sites. We also deployed two types of passive samplers in the water column at the two sites, the newly developed Carbon Nanotube Integrative Samplers for monitoring “CNIS-labile” silver and Diffusive Gradient in Thin Film samplers for monitoring “DGT-labile” silver. Results from these passive samplers indicated that the concentrations of silver at the two sites were either below detection limits or were in the ng/L range. In laboratory experiments where the sediments were re-suspended in Milli-Q water, a small proportion of the silver (i.e., < 25%) was labile and partitioned as colloidal or dissolved silver into the liquid phase after agitation. Nanoparticles tentatively identified as silver nanoparticles were detected by single-particle ICP-MS in suspension after agitation of both suspended and bottom sediments. Therefore, there is a need to assess whether silver species, including silver nanoparticles are transported from wastewater treatment plants into sediments in the aquatic environment. This study is unique in focusing on the in situ distribution of silver in natural waters and in sediments that are potentially impacted by urban sources of nanoparticles.