Merle M. Plassmann

Laboratory Studies on the Fate of Perfluoroalkyl Carboxylates and Sulfonates during Snowmelt

Perfluoroalkyl acids (PFAAs) are anthropogenic chemicals that occur in snow from both remote and source regions. Experiments were conducted to determine how PFAAs are released from a melting snowpack. Different PFAAs eluted from the snowpack at different times, those with short chains eluting early, those with long chains eluting late. The concentrations in the meltwater of PFAAs with medium chain lengths of 6 to 9 perfluorinated carbon atoms first increased and then decreased during the melt period. Such a peak elution had not been previously observed for any other chemicals. The specific snow surface area (SSA) influenced this elution type, with peak concentrations occurring earlier in a snowpack with lower SSA. Model simulations suggested that the snow surface decrease during the melt alone was insufficient to explain the observations. It was ruled out that the calcium concentration affected PFAA sorption to the snow surface in a similar way as sorption to sediments. Adsorption coefficients of PFAAs to the snow surface were estimated by fitting the measured and modeled elution profiles.

Theoretical and experimental simulation of the fate of semifluorinated n-alkanes during snowmelt.

Semifluorinated n-alkanes (SFAs) are highly fluorinated anthropogenic chemicals that are released into the environment through their use in ski waxes. Nothing is known about their environmental partitioning in general and their fate during snowmelt in particular. Properties were estimated for a range of SFAs with different chain lengths and degrees of fluorination using the SPARC calculator and poly parameter linear free energy relationships (ppLFERs). The calculations resulted in very low water solubility and vapor pressures and, consequently, high log KOW and log KOA values. Artificially produced snow in a cold room was spiked with a range of SFAs and subsequently melted with infrared lamps. Melt water, particles, and air samples taken during melting were analyzed. Both calculations and experiments showed that SFAs used in ski waxes will bind to particles or snow grain surfaces during snowmelt and thus are predicted to end up on the soil surface in skiing areas.

Trace Analytical Methods for Semifluorinated n-Alkanes in Snow, Soil, and Air

Semifluorinated n-alkanes (SFAs) are anthropogenic chemicals that are used in ski waxes and, thus, are released directly into the environment, but their subsequent fate and distribution are as yet unknown. Therefore, simple, selective, and sensitive methods were developed for analyzing trace amounts of SFAs in snow/water, soil, and air samples by gas chromatography coupled to electron capture negative ionization mass spectrometry (GC/ECNI-MS). Recoveries were generally in the range of 70-120%, depending on the compound and matrix. The analytical sensitivity was higher for SFAs with longer fluorinated chains, and the instrumental limits of detection ranged from 0.3 to 260 pg injected, providing method detection limits of 0.54-311 ng L(-1), 0.004-9.86 ng g(-1), and 0.4-531 ng m(-3) for snow (analyzed as its meltwater), soil, and air samples, respectively. Using the developed procedures, SFAs were found in snow (meltwater) and soil samples from a small cross-country ski area in Sweden at concentrations up to 1.3 microg L(-1) and 47 pg g(-1), respectively.

Extending analysis of environmental pollutants in human urine towards screening for suspected compounds

Today there is a large difference in the number of chemicals of commerce and the number of chemicals being monitored in environmental and human samples. During the last decades suspect screening methods have been developed to increase the number of monitored analytes. Peaks detected during high resolution mass spectrometry full scan measurements are compared to a list of suspect chemicals with known exact masses. These methods, however, have so far focused on environmental samples. Thus we present a method development for a suspect screening of human urine samples. The sample preparation techniques and instrumental analysis were tested by target chemicals with a wide range of properties. A combination of direct injection and QuEChERS extraction followed by liquid chromatography coupled to high resolution mass spectrometry was able to detect 33 of the 40 spiked target compounds at 30-120% absolute recovery. For suspect evaluation peaks were deconvoluted and aligned with the software MZmine followed by R script processing. Comparing detected and in-silico fragmentation, nine suspect chemicals could be tentatively identified in a pooled human urine sample and four of these were confirmed by a reference standard.

Perfluoroalkyl carboxylic acids with up to 22 carbon atoms in snow and soil samples from a ski area

The use of fluorinated ski waxes as a direct input route of perfluoroalkyl carboxylic acids (PFCAs) to the environment was investigated. PFCA homologues with 6-22 carbon atoms (C6-22 PFCAs) were detected in fluorinated ski waxes and their raw materials by liquid chromatography coupled to tandem mass spectrometry. Snow and soil samples from a ski area in Sweden were taken after a skiing competition and after snowmelt, respectively. In both snow and soil samples C6-22 PFCAs were detected, representing the first report of PFCAs with up to 22 carbon atoms in environmental samples. Single analyte concentrations in snow (analyzed as melt water) and soil ranged up to 0.8μgL(-1) and 5ngg(-1) dry weight, respectively. ∑PFCA concentrations in snow and soil decreased from the start to the finish of the ski trail. Distinct differences in PFCA patterns between snow (prevalence of C14-20 PFCAs) and soil samples (C6-14 PFCAs dominating) were observed. Additionally, a PFCA pattern change from the start to about two third of the distance of the ski trail was found both for snow and soil, with a larger fraction of longer chain homologues present in samples from the start. These observations are probably a result of differences in PFCA homologue patterns present in different types of waxes. The calculated PFCA input from snow affected by the skiing competition was smaller than the PFCA inventory in soil for all chain lengths and markedly smaller for C6-15 PFCAs, presenting evidence for long-term accumulation in soil.

Environmental occurrence and fate of semifluorinated n-alkanes in snow and soil samples from a ski area

Semifluorinated n-alkanes (SFAs) with carbon chain lengths of 22 to approximately 36 atoms are present in fluorinated ski waxes to reduce the friction between ski base and snow, resulting in a better glide. Semifluorinated n-alkenes (SFAenes) are byproducts in the production process of SFAs and are also found in ski waxes. Snow and soil samples from a ski area in Sweden were taken after a large skiing competition and after snowmelt, respectively, and analyzed for SFAs and SFAenes. Single analyte concentrations in snow (analyzed as melt water) ranged from a few ng L(-1) up to 300 μg L(-1). ∑SFA concentrations decreased significantly from the start to the finish of the ski trail. Single analyte concentrations in soil ranged up to 9 ng g(-1)dw. ∑SFA concentrations in soil did not show a trend along the ski trail. This may be due to the fact that concentrations in soil, although strongly influenced by the competition, reflect inputs during the whole skiing season. The chemical inventory in snow was greater than the inventory in soil for shorter chain SFAs (C(22)C(28)) and for all SFAenes. Additionally, a significant change in SFA patterns between snow and soil samples was found. These observations suggested volatilization of shorter chain SFAs and of SFAenes during snowmelt. Evidence for long-term accumulation of SFAs in surface soil over several skiing seasons was not found.

Bioconcentration and Biotransformation of Amitriptyline in Gilt-Head Bream

Extensive global use of the serotonin-norepinephrine reuptake inhibitor Amitriptyline (AMI) for treatment of mental health problems has led to its common occurrence in the aquatic environment. To assess AMI bioconcentration factors, tissue distribution, and metabolite formation in fish, we exposed gilt-head bream (Sparus aurata) to AMI in seawater for 7 days at two concentrations (0.2 μg/L and 10 μg/L). Day 7 proportional bioconcentration factors (BCFs) ranged from 6 (10 μg/L dose, muscle) to 127 (0.2 μg/L dose, brain) and were consistently larger at the low dose level. The relative tissue distribution of AMI was consistent at both doses, with concentrations decreasing in the order brain ≈ gill > liver > plasma > bile ≫ muscle. Using a suspect screening workflow based on liquid chromatography-high resolution (Orbitrap) mass spectrometry we identified 33 AMI metabolites (both Phase I and Phase II), occurring mostly in bile, liver and plasma. Ten structures are reported for the first time. Remarkably, all 33 metabolites retained the tricyclic ring structure common to tricyclic antidepressants, which may be toxicologically relevant. Collectively these data indicate that, in addition to AMI, a broad suite of metabolites should be included in biomonitoring campaigns in order to fully characterize exposure in aquatic wildlife.