Nicholas A Warner

Volatile siloxanes in the European arctic: assessment of sources and spatial distribution.

The purpose of this study was to investigate presence and potential accumulation of cyclic volatile methyl siloxanes (cVMS) in the Arctic environment. Octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were analyzed in sediment, zooplankton, Atlantic cod (Gadus morhua), shorthorn sculpin (Myxocephalus scorpius), and bearded seal (Erignathus barbatus) collected from the Svalbard archipelago within the European Arctic in July 2009. Highest levels were found for D5 in fish collected from Adventfjorden, with average concentrations of 176 and 531 ng/g lipid in Atlantic cod and shorthorn sculpin, respectively. Decreasing concentration of D5 in sediment collected away from waste water outlet in Adventfjorden indicates that the local settlement of Longyearbyen is a point source to the local aquatic environment. Median biota sediment accumulation factors (BSAFs) calculated for D5 in Adventfjorden were 2.1 and 1.5 for Atlantic cod and shorthorn sculpin, respectively. Biota concentrations of D5 were lower or below detection limits in remote and sparsely populated regions (Kongsfjorden and Liefdefjorden) compared to Adventfjorden. The levels of cVMS were found to be low or below detection limits in bearded seal blubber and indicate a low risk for cVMS accumulation within mammals. Accumulation of cVMS in fish appears to be influenced by local exposure from human settlements within the Arctic.

Seasonality in contaminant accumulation in Arctic marine pelagic food webs using trophic magnification factor as a measure of bioaccumulation

Seasonality in biomagnification of persistent organic pollutants (POPs; polychlorinated biphenyls, chlorinated pesticides, and brominated flame retardants) in Arctic marine pelagic food webs was investigated in Kongsfjorden, Svalbard, Norway. Trophic magnification factors (TMFs; average factor change in concentration between two trophic levels) were used to measure food web biomagnification in biota in May, July, and October 2007. Pelagic zooplankton (seven species), fish (five species), and seabirds (two species) were included in the study. For most POP compounds, highest TMFs were found in July and lowest were in May. Seasonally changing TMFs were a result of seasonally changing POP concentrations and the δ¹⁵N-derived trophic positions of the species included in the food web. These seasonal differences in TMFs were independent of inclusion/exclusion of organisms based on physiology (i.e., warm- versus cold-blooded organisms) in the food web. The higher TMFs in July, when the food web consisted of a higher degree of boreal species, suggest that future warming of the Arctic and increased invasion by boreal species can result in increased food web magnification. Knowledge of the seasonal variation in POP biomagnification is a prerequisite for understanding changes in POP biomagnification caused by climate change.

Differences between Arctic and Atlantic fjord systems on bioaccumulation of persistent organic pollutants in zooplankton from Svalbard

Differences in bioaccumulation of persistent organic pollutants (POPs) between fjords characterized by different water masses were investigated by comparing POP concentrations, patterns and bioaccumulation factors (BAFs) in seven species of zooplankton from Liefdefjorden (Arctic water mass) and Kongsfjorden (Atlantic water mass), Svalbard, Norway. No difference in concentrations and patterns of POPs was observed in seawater and POM; however higher concentrations and BAFs for certain POPs were found in species of zooplankton from Kongsfjorden. The same species were sampled in both fjords and the differences in concentrations of POPs and BAFs were most likely due to fjord specific characteristics, such as ice cover and timing of snow/glacier melt. These confounding factors make it difficult to conclude on water mass (Arctic vs. Atlantic) specific differences and further to extrapolate these results to possible climate change effects on accumulation of POPs in zooplankton. The present study suggests that zooplankton do biomagnify POPs, which is important for understanding contaminant uptake and flux in zooplankton, though consciousness regarding the method of evaluation is important.

Influence of season, location, and feeding strategy on bioaccumulation of halogenated organic contaminants in Arctic marine zooplankton

The influence of season, location, feeding strategy, and trophic position on concentration, compositional pattern, and bioaccumulation factors (BAFs) of halogenated organic contaminants (HOCs; polychlorinated biphenyls, chlorinated pesticides, and brominated flame retardants) was investigated within an Arctic zooplankton food web. Water (dissolved fraction) and seven Arctic marine pelagic zooplankton species (including herbivores, omnivores, and predators) were sampled in May, July, and October 2007 at two stations in Kongsfjorden, Svalbard, Norway. The HOC concentrations in both water and zooplankton generally decreased from May to October. The HOC concentrations and patterns among zooplankton species were explained by their feeding strategies, roughly categorized as herbivores, omnivores, and predators, and not stable isotope-derived trophic position. Field-derived BAFs varied greatly, with higher BAFs in May compared with July and October. Furthermore, BAFs differed among the species according to their feeding strategies. The relationship between BAFs from the different seasons and K(OW) (octanol:water partitioning coefficient) showed comparable intercepts and different slopes between May and October, with all relationships diverging from the assumed 1:1 relationship between BAF and K(OW). Differences in HOC concentrations and BAFs from herbivores to predators showed that biomagnification occurred in zooplankton. The results suggest that concentrations and patterns of HOCs in zooplankton species are influenced not only by equilibrium partitioning with water but also by feeding strategy.

Plasma concentrations of cyclic volatile methylsiloxanes (cVMS) in pregnant and postmenopausal Norwegian women and self-reported use of personal care products (PCPs)

Dermal application of personal care products (PCPs) is considered an important human exposure route for siloxanes. Their presence as minor or major constituents in many personal care products (PCPs) and cosmetics is of concern for human exposure. The aim of this study was to quantify cyclic volatile methylsiloxanes (cVMS) in blood plasma of pregnant and postmenopausal women, and to investigate possible links to self-reported use of PCPs for the latter group. Participants were recruited from two studies, namely the Norwegian Women and Cancer Study (NOWAC) and the North Norwegian Mother-and-child Study (MISA). For the NOWAC cohort, 94 plasma samples from postmenopausal women were analyzed (blood drawn in 2005) and information about PCP use and breast implants was derived from a self-administered questionnaire. In the MISA study, the collection of the plasma samples (blood drawn in 2009) constituted a re-sampling because the original serum vacutainers used were contaminated with cVMS. D4 (octamethylcyclotetrasiloxane) was the dominant compound in plasma for both cohorts. For the NOWAC samples, more than 85% of the women had D4 concentrations above the LOQ (2.74 ng/mL), while the detection frequency was only 18% for the MISA participants. The highest cVMS plasma concentrations were observed for D4: 12.7 ng/mL (NOWAC) and 2.69 ng/mL (MISA). For the other cVMS, decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) concentrations were below the detection limit in most samples. There was no significant correlation between the concentrations of D4 and the reported total body cream use. Sampling time (2005 versus 2009) and age of the donors could explain the differences between the two cohorts.

Positive vs. false detection: a comparison of analytical methods and performance for analysis of cyclic volatile methylsiloxanes (cVMS) in environmental samples from remote regions.

Contamination and analytical variation can significantly hinder trace analysis of cyclic methyl volatile siloxanes (cVMS); potentially resulting in the report of false positives at concentrations approaching detection limits. To assess detection and variation associated with trace cVMS analysis in environmental matrices, a co-operative laboratory comparison for the analysis of octametylcyclotetrasiloxane (D4), decamethylcylcopentasiloxane (D5), and dodecametylcyclohexasiloxane (D6) in sediment and biota from the Svalbard Archipelago was conducted. Two definitions of detection limits were evaluated in this study; method detection limits (MDL, matrix defined) and limits of detection (LOD, solvent defined). D5 was the only cVMS detected above both LOD (0.08-0.81ngg(-1)ww) and MDL (0.47-2.36ngg(-1)ww) within sediment by all laboratories where concentrations ranged from 0.55 to 3.91ngg(-1)ww. The percentage of positive detects for D5 decreased by 80% when MDL was defined as the detection limit. D5 was also detected at the highest frequency among all laboratories in fish liver with concentrations ranging from 0.72 to 345ngg(-1)ww. Similar to sediment, percentage of positive detects for D5 decreased by 60% across all laboratories for fish livers when using MDL (0.68-3.49ngg(-1)ww). Similar observations were seen with both D4 and D6, indicating that sample matrix significantly contributes to analytical response variation. Despite differences in analytical methods used between laboratories, good agreement was obtained when using MDL to define detection limits. This study shows the importance of incorporating variation introduced by sample matrices into detection limit calculations to insure data accuracy of cVMS at low concentrations.

A broad cocktail of environmental pollutants found in eggs of three seabird species from remote colonies in Norway

Eggs of 3 seabird species, common eider (Somateria mollisima), European shag (Phalacrocorax aristotelis aristotelis), and European herring gull (Larus argentatus), were surveyed for a broad range of legacy and emerging pollutants to assess chemical mixture exposure profiles of seabirds from the Norwegian marine environment. In total, 201 chemical substances were targeted for analysis ranging from metals, organotin compounds, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and associated metabolites, chlorinated paraffins, chlorinated and nonchlorinated organic pesticides, per- and polyfluoroalkyl substances (PFAS), dechlorane plus, octachlorostyrene, brominated flame retardants (BFRs), organophosphorous compounds, brominated and alkyl phenols, cyclic siloxanes, and phthalates. Of the chemicals targeted, 149 substances were found above the detection limits, with metals dominating the contaminant profile and comprising 60% of the total contaminant load. Polychlorinated biphenyls, pesticides, organophosphorous compounds, and PFAS were the dominant contaminant classes of organic pollutants found within the seabird species, with the highest loads occurring in herring gulls, followed by shag, and common eider. New generation pollutants (e.g., PFAS, organophosphorous compounds, and alkylphenols) were detected at similar or higher concentrations than the legacy persistent organic pollutants (POPs). Time trends of reported concentrations of legacy POPs appear to have decreased in recent decades from the Norwegian coastal environment. Concentrations of detected pollutants do not appear to have a negative effect on seabird population development within the sampling area. Additional stress caused by pollutants, however, may affect seabird health more at the individual level.

Allometric relationships to liver tissue concentrations of cyclic volatile methyl siloxanes in Atlantic cod

Spatial distribution and relationship of allometric measurements (length, weight and age) to liver concentrations of cyclic volatile methyl siloxanes (cVMS) including octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclosiloxane (D6) in Atlantic cod (Gadus morhua) collected near the community of Tromsø in Northern Norway were assessed. These congeners were benchmarked against known persistent polychlorinated biphenyls (PCBs 153 and 180) to assess accumulation behavior of cVMS. D5 was the dominate cVMS detected in all fish livers with lipid normalized concentrations up to 10 times or greater than those observed for PCB 153 and 180. D4 and D6 concentration were negatively correlated with fish length and weight, indicating a greater elimination capacity compared to uptake processes with increasing fish size for these chemicals. These results indicate relationships between allometric measurements and cVMS concentrations may account for concentration variations observed within fish and should be assessed in future studies evaluating cVMS bioaccumulation potential.

Understanding of Cyclic Volatile Methyl Siloxane Fate in a High Latitude Lake Is Constrained by Uncertainty in Organic Carbon− Water Partitioning

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-1 organic 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.

Spatial and temporal distribution of chiral pesticides in Calanus spp. from three Arctic fjords

Concentration and enantiomeric fractions (EFs) of chiral chlorinated pesticides (α-hexachlorocyclohexane (α-HCH), trans-, cis- and oxychlordane) were determined in Arctic zooplankton, mainly Calanus spp. collected in the period 2007-11 from Svalbard fjords and open pack-ice. The temporal and spatial enantiomer distribution varied considerably for all species and chiral pesticides investigated. An overall enantiomeric excess of (+)-oxychlordane (EF 0.53-0.86) were observed. Cis-chlordane was close to racemic (EF 0.46-0.55), while EF for trans-chlordane varied between 0.29 and 0.55, and between 0.38 and 0.59 for α-HCH. The biodegradation potential for trans-chlordane was higher compared to cis-chlordane. The comprehensive statistical evaluation of the data set revealed that the EF distribution of α-HCH was affected by ice cover to a higher extent compared to cis-chlordane. Potential impact from benthic processes on EFs in zooplankton is an interesting feature and should be further investigated. Enantiomeric selective analyses may be a suitable tool for investigations of climate change related influences on Arctic ecosystems.