Found 2696 publications. Showing page 80 of 270:
In order to evaluate the potential impact of the Arctic anthropogenic emission sources it is essential to understand better the natural aerosol sources of the inner Arctic and the atmospheric processing of the aerosols during their transport in the Arctic atmosphere. A 1-year time series of chemically specific measurements of the sub-micrometre aerosol during 2015 has been taken at the Mt. Zeppelin observatory in the European Arctic. A source apportionment study combined measured molecular tracers as source markers, positive matrix factorization, analysis of the potential source distribution and auxiliary information from satellite data and ground-based observations. The annual average sub-micrometre mass was apportioned to regional background secondary sulphate (56%), sea spray (17%), biomass burning (15%), secondary nitrate (5.8%), secondary marine biogenic (4.5%), mixed combustion (1.6%), and two types of marine gel sources (together 0.7%). Secondary nitrate aerosol mainly contributed towards the end of summer and during autumn. During spring and summer, the secondary marine biogenic factor reached a contribution of up to 50% in some samples. The most likely origin of the mixed combustion source is due to oil and gas extraction activities in Eastern Siberia. The two marine polymer gel sources predominantly occurred in autumn and winter. The small contribution of the marine gel sources at Mt. Zeppelin observatory in summer as opposed to regions closer to the North Pole is attributed to differences in ocean biology, vertical distribution of phytoplankton, and the earlier start of the summer season.
2019
In the present study, concentrations of legacy and emerging contaminants were determined in three non-destructive matrices (plasma, preen oil and body feathers) of northern goshawk (Accipiter gentilis) nestlings. Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) and polybrominated diphenyl ethers (PBDEs), together with emerging pollutants, including per- and polyfluorinated alkyl substances (PFASs), novel brominated flame retardants (NBFRs), phosphorus flame retardants (PFRs) and Dechlorane Plus isomers (DPs) were targeted. Plasma, preen oil and feather samples were collected from 61 goshawk nestlings in Norway (Trøndelag and Troms) in 2015 and 2016, and pollutant concentrations were compared between the three matrices. In plasma, PFASs were detected in the highest concentrations, ranging between 1.37 and 36.0 ng/mL, which suggests that the nestlings were recently and continuously exposed to these emerging contaminants, likely through dietary input. In preen oil, OCPs (169–3560 ng/g) showed the highest concentrations among the investigated compounds, consistent with their high lipophilicity. PFRs (2.60–314 ng/g) were the dominant compounds in feathers and are thought to originate mainly from external deposition, as they were not detected in the other two matrices. NBFRs and DPs were generally not detected in the nestlings, suggesting low presence of these emerging contaminants in their environment and/or low absorption. Strong and significant correlations between matrices were found for all POPs (rs = 0.46–0.95, p < 0.001), except for hexachlorobenzene (HCB, rs = 0.20, p = 0.13). Correlations for PFASs were less conclusive: linear perfluorooctane sulfonate (PFOS), perfluoroundecanoate (PFUnA), perfluorododecanoate (PFDoA) and perfluorotetradecanoate (PFTeA) showed strong and significant correlations between plasma and feathers (rs = 0.42–0.72, p < 0.02), however no correlation was found for perfluorohexane sulfonate (PFHxS), perfluorononanoate (PFNA) and perfluorotridecanoate (PFTriA) (rs = 0.05–0.33, p = 0.09–0.85). A lack of consistency between the PFAS compounds (contrary to POPs), and between studies, prevents concluding on the suitability of the investigated matrices for PFAS biomonitoring.
2019
Nanomaterial grouping: Existing approaches and future recommendations
The physico-chemical properties of manufactured nanomaterials (NMs) can be fine-tuned to obtain different functionalities addressing the needs of specific industrial applications. The physico-chemical properties of NMs also drive their biological interactions. Accordingly, each NM requires an adequate physico-chemical characterization and potentially an extensive and time-consuming (eco)toxicological assessment, depending on regulatory requirements. Grouping and read-across approaches, which have already been established for chemicals in general, are based on similarity between substances and can be used to fill data gaps without performing additional testing. Available data on “source” chemicals are thus used to predict the fate, toxicokinetics and/or (eco)toxicity of structurally similar “target” chemical(s). For NMs similar approaches are only beginning to emerge and several challenges remain, including the identification of the most relevant physico-chemical properties for supporting the claim of similarity. In general, NMs require additional parameters for a proper physico-chemical description. Furthermore, some parameters change during a NM's life cycle, suggesting that also the toxicological profile may change.
This paper compares existing concepts for NM grouping, considering their underlying basic principles and criteria as well as their applicability for regulatory and other purposes. Perspectives and recommendations based on experiences obtained during the EU Horizon 2020 project NanoReg2 are presented. These include, for instance, the importance of harmonized data storage systems, the application of harmonized scoring systems for comparing biological responses, and the use of high-throughput and other screening approaches. We also include references to other ongoing EU projects addressing some of these challenges.
2019
2019
2019
2019
A combination of local (i.e. firefighting training facilities) and remote sources (i.e., long-range transport) are assumed to be responsible for the occurrence of per- and polyfluoroalkyl substances (PFASs) in Svalbard (Norwegian Arctic). However, no systematic elucidation of local PFASs sources have been conducted yet. Therefore, a survey was performed aiming at identifying local PFASs pollution sources on the island of Spitsbergen (Svalbard, Norway). Soil, fresh water (lake, draining rivers), sea water, melt-water run-off, surface snow and coastal sediment samples were collected from Longyearbyen (Norwegian mining town), Ny-Ålesund (research facility) and the Lake Linnévatnet area (background site) during several campaigns (2014-2016) and analysed for 14 individual target PFASs. For background site (Linnévatnet area, sampling during April to June 2015), ∑PFAS levels ranged from 0.4 – 4 ng/L in surface lake water (n = 20). PFAS in melt water from the contributing glaciers showed similar concentrations (~4 ng/L, n = 2). The short chain perfluorobutanoate (PFBA) was predominant in lake water (60-80% of the ∑PFASs), meltwater (20-30 %) and run-off water (40 %). Long range transport is assumed to be the major PFAS source. In Longyearbyen, 5 water samples (i.e. 2 seawater, 3 run-off) were collected near the local firefighting training site (FFTS) in November 2014 and June 2015, respectively. The highest PFAS levels were found in FFTS melt water run-off (118 ng/L). PFOS was the most abundant compound in the FFTS meltwater run-off (53 – 58 % PFASs). At the research station Ny-Ålesund, sea water (n = 6), soil (n = 9) and fresh water (n = 10) were collected in June 2016. Low ∑PFAS concentrations were determined for sea water (5 - 6 ng/L), whereas high ∑PFAS concentrations were found in run-off water (113 – 119 ng/L) and soil (211 – 800 ng/g dry weight (dw)) collected close to the local FFTS. In addition, high ∑PFAS levels (127 ng/L) were also found in fresh water from lake Solvatnet close to former sewage treatment facility. Overall, at both FFTS affected sites (soil, water), PFOS was the most abundant compound (60 – 69% of ∑PFASs). FFTS and landfill locations were identified as major PFASs sources for Svalbard settlements.
2018
Sudden Stratospheric Warmings (SSW) affect the chemistry and dynamics of the middle atmosphere. Major warmings occur roughly every second winter in the Northern Hemisphere (NH), but has only been observed once in the Southern Hemisphere (SH), during the Antarctic winter of 2002. Observations by the Global Ozone Monitoring by Occultation of Stars (GOMOS, an instrument on board Envisat) during this rare event, show a 40% increase of ozone in the nighttime secondary ozone layer at subpolar latitudes compared to non-SSW years. This study investigates the cause of the mesospheric nighttime ozone increase, using the National Center for Atmospheric Research (NCAR) Whole Atmosphere Community Climate Model with specified dynamics (SD-WACCM). The 2002 SH winter was characterized by several reductions of the strength of the polar night jet in the upper stratosphere before the jet reversed completely, marking the onset of the major SSW. At the time of these wind reductions, corresponding episodic increases can be seen in the modelled nighttime secondary ozone layer. This ozone increase is attributed largely to enhanced upwelling and the associated cooling of the altitude region in conjunction with the wind reversal. This is in correspondence to similar studies of SSW induced ozone enhancements in NH. But unlike its NH counterpart, the SH secondary ozone layer appeared to be impacted less by episodic variations in atomic hydrogen. Seasonally decreasing atomic hydrogen plays however a larger role in SH compared to NH.
2018
2018
An Infrastructural Analysis of a Crowdsourcing Tool for Environmental Research
In this paper, we adopt information infrastructure design principles and concepts from the theory of critical mass to analyze and evaluate the socio-technical conditions that hindered the successful bootstrapping processes of a crowdsourcing tool for environmental research. The crowdsourcing tool was designed to improve the estimation of emissions from burning wood for residential heating in urban areas in Norway by collecting geolocation data on wood consumption and stove types. Our analysis identifies three groups of users, namely scientists, wood consumers (end users), and key stakeholders, that the IT capability of the tool needs to support. At this stage, we determined that the tool was more useful to the scientists than the other two groups, which was attributed to its low uptake. We uncovered various underlying issues through further analysis of means by which the tool becomes useful to key stakeholders. One particular issue concerned the tension between existing data collection practices, which are based on statistical methods, and the nature of crowdsourcing, which is based on the principle of open call with no sampling techniques. From our analysis, we concluded that developing crowdsourcing tools for research requires increasing the tool’s benefits for key stakeholders by addressing these underlying issues. Inferring from the theory of critical mass for collective action, we recommend that developers of crowdsourcing tools include a function that allows users to view the contributions of other users.
2018