title: Understanding of Cyclic Volatile Methyl Siloxane Fate in a High Latitude Lake Is Constrained by Uncertainty in Organic Carbon-Water Partitioning.
abstract: Cyclic volatile methyl siloxanes (cVMS) are emitted to aquatic environments with wastewater effluents. Here, we evaluate the environmental behavior of three cVMS compounds (octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6)) in a high latitude lake (Storvannet, 70°N 23°E), experiencing intermittent wastewater emissions and high latitude environmental conditions (low temperatures and seasonal ice cover). Measured cVMS concentrations in lake water were below detection limits in both March and June 2014. However, mean concentrations in sediments were 207 ± 30, 3775 ± 973 and 848 ± 211 ng g-1organic carbon for D4, D5 and D6, respectively. To rationalize measurements, a fugacity-based model for lakes (QWASI) was parametrized for Storvannet. The key removal process for cVMS from the lake was predicted to be advection due to the low hydraulic retention time of the lake, followed by volatilization. Predicted cVMS behavior was highly sensitive to the partition coefficient between organic carbon and water (KOC) and its temperature dependence. Predictions indicated lower overall persistence with decreasing temperature due to enhanced partitioning from sediments to water. Inverse modeling to predict steady-state emissions from cVMS concentrations in sediment provided unrealistically high emissions, when evaluated against measured concentrations in sewage. However, high concentrations of cVMS in sediment and low concentrations in water could be explained via a hypothetical dynamic emission scenario consistent with combined sewer overflows. The study illustrates the importance of considering compound-specific behavior of emerging contaminants that may differ from legacy organic contaminants.
authors.affiliation: NILU - Norwegian Institute for Air Research, The Fram Centre , P.O. Box 6606 Langnes, 9296 Tromsø, Norway.
authors.forename: Ingjerd Sunde
authors.identifier: 0000-0002-6063-6655
authors.initials: IS
authors.lastname: Krogseth
authors.affiliation: Department of Geography, University of Leicester , Leicester LE1 7RH, United Kingdom.
authors.forename: Michael John
authors.initials: MJ
authors.lastname: Whelan
authors.affiliation: Akvaplan-niva AS, The Fram Centre , P.O. Box 6606 Langnes, 9296 Tromsø, Norway.
authors.forename: Guttorm Normann
authors.initials: GN
authors.lastname: Christensen
authors.affiliation: NILU - Norwegian Institute for Air Research , P.O. Box 100, 2027 Kjeller, Norway.|Department of Chemistry, University of Oslo , P.O. Box 1033, Blindern, 0315 Oslo, Norway.
authors.forename: Knut
authors.initials: K
authors.lastname: Breivik
authors.affiliation: Akvaplan-niva AS, The Fram Centre , P.O. Box 6606 Langnes, 9296 Tromsø, Norway.
authors.forename: Anita
authors.initials: A
authors.lastname: Evenset
authors.affiliation: NILU - Norwegian Institute for Air Research, The Fram Centre , P.O. Box 6606 Langnes, 9296 Tromsø, Norway.
authors.forename: Nicholas Alexander
authors.initials: NA
authors.lastname: Warner
mesh_terms: D002244:Carbon; D004784:Environmental Monitoring; D060106:Lakes; D012833:Siloxanes; D035501:Uncertainty; D014867:Water; D014874:Water Pollutants, Chemical
chemical_list: D012833:Siloxanes; D014874:Water Pollutants, Chemical; D014867:Water; D002244:Carbon