Found 9763 publications. Showing page 211 of 391:
The present study examined how climate changes may impact the concentrations of lipophilic organochlorines (OCs) in the blood of fasting High Arctic common eiders (Somateria mollissima) during incubation. Polychlorinated biphenyls (PCBs), 1-dichloro-2,2-bis (p-chlorophenyl) ethylene (p,p′-DDE), hexachlorobenzene (HCB) and four chlordane compounds (oxychlordane, trans-chlordane and trans- and cis-nonachlor) were measured in females at chick hatching (n = 223) over 11 years (2007–2017). Firstly, median HCB and p,p′-DDE concentrations increased ~75 % over the study period, whereas median chlordane concentrations doubled (except for oxychlordane). PCB concentrations, in contrast, remained stable over the study period. Secondly, both body mass and clutch size were negatively associated with OC levels, suggesting that females with high lipid metabolism redistributed more OCs from adipose tissue, and that egg production is an important elimination route for OCs. Thirdly, the direct climate effects were assessed using the mean effective temperature (ET: air temperature and wind speed) during incubation, and we hypothesized that a low ET would increase redistribution of OCs. Contrary to expectation, the ET was positively correlated to most OCs, suggesting that a warmer climate may lead to higher OCs levels, and that the impact of ET may not be direct. Finally, potential indirect impacts were examined using the Arctic Oscillation (AO) in the three preceding winters (AOwinter 1–3) as a proxy for potential long-range transport of OCs, and for local spring climate conditions. In addition, we used chlorophyll a (Chla) as a measure of spring primary production. There were negative associations between AOwinter 1 and HCB, trans-chlordane and trans-nonachlor, whereas oxychlordane and cis-chlordane were negatively associated with Chla. This suggests that potential indirect climate effects on eiders were manifested through the food chain and not through increased long-range transport, although these relationships were relatively weak.
Elsevier
2023
2004
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2006
Microfibers (MFs) are frequently reported as the most dominant type of microplastic (MP) found in the marine water column and sediments. A major source of MFs is the use and washing of textiles. Although WWTPs can remove up to 98% of MP, estimates suggest billions of MP are still released from a single WWTP annually. Intrinsic properties (polymer type, density, size) will influence environmental degradation, settling times, and ingestion of MFs by marine organisms. Less well understood is the influence of environmental degradation on the fate of MFs. In the current study, we compare the effect of UV exposure on the degradation and fragmentation of polyester (PET), polyamide (nylon; PA), polyacrylonitrile (acrylic; PAN) and wool fibers. Degradation of MFs was conducted in seawater under environmentally relevant exposure conditions using simulated sunlight. PA, PET and wool MFs exhibited changes in surface morphology after just 2 weeks from the start of exposure, followed by fragmentation after
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2022
Impact of the Pacific sector sea ice loss on the sudden stratospheric warming characteristics
The atmospheric response to Arctic sea ice loss remains a subject of much debate. Most studies have focused on the sea ice retreat in the Barents-Kara Seas and its troposphere-stratosphere influence. Here, we investigate the impact of large sea ice loss over the Chukchi-Bering Seas on the sudden stratospheric warming (SSW) phenomenon during the easterly phase of the Quasi-Biennial Oscillation through idealized large-ensemble experiments based on a global atmospheric model with a well-resolved stratosphere. Although culminating in autumn, the prescribed sea ice loss induces near-surface warming that persists into winter and deepens as the SSW develops. The resulting temperature contrasts foster a deep cyclonic circulation over the North Pacific, which elicits a strong upward wavenumber-2 activity into the stratosphere, reinforcing the climatological planetary wave pattern. While not affecting the SSW occurrence frequency, the amplified wave forcing in the stratosphere significantly increases the SSW duration and intensity, enhancing cold air outbreaks over the continents afterward.
Springer Nature
2022
2023
2023
2023
The Arctic middle atmosphere was affected by major sudden stratospheric warmings (SSW) in February 2018 and January 2019, respectively. In this article, we report for the first time the impact of these two events on the middle atmospheric nitric oxide (NO) abundance. The study is based on measurements obtained during two dedicated observation campaigns, using the Sub-Millimetre Radiometer (SMR) aboard the Odin satellite, measuring NO globally since 2003. The SSW of February 2018 was similar to other, more dynamically quiet, Arctic winters in term of NO downward transport from the upper mesosphere–lower thermosphere to lower altitudes (referred to as energetic particle precipitation indirect effect EPP-IE). On the contrary, the event of January 2019 led to one of the strongest EPP-IE cases observed within the Odin operational period. Important positive NO anomalies were indeed observed in the lower mesosphere–upper stratosphere during the three months following the SSW onset, corresponding to NO volume mixing ratios more than 50 times higher than the climatological values. These different consequences on the middle atmospheric composition are explained by very different dynamical characteristics of these two SSW events.
Elsevier
2021
2021
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