Presentation abstract
Presentation abstract
Understanding the intake, body burden and elimination of perfluorooctane sulfonate and perfluorooctanoic acid in the North American population: A modelling approach
Presentation abstract
Is there an unknown exposure pathway for PBDEs – evidence from North American biomonitoring data.
Presentation abstract
Understanding the exposure, body concentration and elimination of PFASs in the North American population.
Presentation abstract
Confronting Unknown Planetary Boundary Threats from Chemical Pollution.
Presentation abstract
Why do women eliminate PFOS faster than men?
Scientific paper
Junge relationships in measurement data for cyclic siloxanes in air
atmosphere
,
chemicals
,
d-3
,
d-4
,
d-5
,
d-6
,
ftoh
,
lifetime
,
multimedia models
,
oh
,
persistence
,
variability-lifetime relationship
In 1974, Junge postulated a relationship between variability of concentrations of gases in air at remote locations and their atmospheric residence time, and this Junge relationship has subsequently been observed empirically for a range of trace gases. Here, we analyze two previously-published datasets of concentrations of cyclic volatile methyl siloxanes (cVMS) in air and find Junge relationships in both. The first dataset is a time series of concentrations of decamethylcyclopentasiloxane (D-5) measured between January and June, 2009 at a rural site in southern Sweden that shows a Junge relationship in the temporal variability of the measurements. The second dataset consists of measurements of hexamethylcyclotrisiloxane (D-3), octamethylcyclotetrasiloxane (D-4) and D-5 made simultaneously at 12 sites in the Global Atmospheric Passive Sampling (GAPS) network that shows a Junge relationship in the spatial variability of the three cVMS congeners. We use the Junge relationship for the GAPS dataset to estimate atmospheric lifetimes of dodecamethylcyclohexasiloxane (D-6), 8:2-fluorotelomer alcohol and trichlorinated biphenyls that are within a factor of 3 of estimates based on degradation rate constants for reaction with hydroxyl radical determined in laboratory studies. (C) 2012 Elsevier Ltd. All rights reserved.
Presentation abstract
Global environmental fate of C6-C10 perfluoroalkane sulfonic acid (PFSA) homologues from 1958 to 2030: sources and transport.
Scientific paper
Concentrations in ambient air and emissions of cyclic volatile methylsiloxanes in Zurich, Switzerland
Tens of thousands of tonnes of cyclic volatile methylsiloxanes (cVMS) are used each year globally, which leads to high and continuous cVMS emissions to air. However, field measurements of cVMS in air and empirical information about emission rates to air are still limited. Here we present measurements of decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) in air for Zurich, Switzerland. The measurements were performed in January and February 2011 over a period of eight days and at two sites (city center and background) with a temporal resolution of 6–12 hours. Concentrations of D5 and D6 are higher in the center of Zurich and range from 100 to 650 ng m−3 and from 10 to 79 ng m−3, respectively. These values are among the highest levels of D5 and D6 reported in the literature. In a second step, we used a multimedia environmental fate model parameterized for the region of Zurich to interpret the levels and time trends in the cVMS concentrations and to back-calculate the emission rate of D5 and D6 from the city of Zurich. The average emission rates obtained for D5 and D6 are 120 kg d–1 and 14 kg d–1, respectively, which corresponds to per-capita emissions of 310 mg capita−1 d−1 for D5 and 36 mg capita−1 d−1 for D6.
