Microplastics are increasingly recognized as ubiquitous global contaminants, but questions linger regarding their source, transport and fate. We document the widespread distribution of microplastics ...in near-surface seawater from 71 stations across the European and North American Arctic - including the North Pole. We also characterize samples to a depth of 1,015 m in the Beaufort Sea. Particle abundance correlated with longitude, with almost three times more particles in the eastern Arctic compared to the west. Polyester comprised 73% of total synthetic fibres, with an east-to-west shift in infra-red signatures pointing to a potential weathering of fibres away from source. Here we suggest that relatively fresh polyester fibres are delivered to the eastern Arctic Ocean, via Atlantic Ocean inputs and/or atmospheric transport from the South. This raises further questions about the global reach of textile fibres in domestic wastewater, with our findings pointing to their widespread distribution in this remote region of the world.
When a polarized light beam is incident upon the surface of a magnetic material, the reflected light undergoes a polarization rotation
. This magneto-optical Kerr effect (MOKE) has been intensively ...studied in a variety of ferro- and ferrimagnetic materials because it provides a powerful probe for electronic and magnetic properties
as well as for various applications including magneto-optical recording
. Recently, there has been a surge of interest in antiferromagnets (AFMs) as prospective spintronic materials for high-density and ultrafast memory devices, owing to their vanishingly small stray field and orders of magnitude faster spin dynamics compared to their ferromagnetic counterparts
. In fact, the MOKE has proven useful for the study and application of the antiferromagnetic (AF) state. Although limited to insulators, certain types of AFMs are known to exhibit a large MOKE, as they are weak ferromagnets due to canting of the otherwise collinear spin structure
. Here we report the first observation of a large MOKE signal in an AF metal at room temperature. In particular, we find that despite a vanishingly small magnetization of
~0.002 µ
/Mn, the non-collinear AF metal Mn
Sn
exhibits a large zero-field MOKE with a polar Kerr rotation angle of 20 milli-degrees, comparable to ferromagnetic metals. Our first-principles calculations have clarified that ferroic ordering of magnetic octupoles in the non-collinear Néel state
may cause a large MOKE even in its fully compensated AF state without spin magnetization. This large MOKE further allows imaging of the magnetic octupole domains and their reversal induced by magnetic field. The observation of a large MOKE in an AF metal should open new avenues for the study of domain dynamics as well as spintronics using AFMs.
Synthetic fibers are increasingly seen to dominate microplastic pollution profiles in aquatic environments, with evidence pointing to textiles as a potentially important source. However, the loss of ...microfibers from textiles during laundry is poorly understood. We evaluated microfiber release from a variety of synthetic and natural consumer apparel textile samples (n = 37), with different material types, constructions, and treatments during five consecutive domestic laundry cycles. Microfiber loss ranged from 9.6 mg to 1,240 mg kg.sup.-1 of textile per wash, or an estimated 8,809 to > 6,877,000 microfibers. Mechanically-treated polyester samples, dominated by fleeces and jerseys, released six times more microfibers (161 ± 173 mg kg.sup.-1 per wash) than did nylon samples with woven construction and filamentous yarns (27 ± 14 mg kg.sup.-1 per wash). Fiber shedding was positively correlated with fabric thickness for nylon and polyester. Interestingly, cotton and wool textiles also shed large amounts of microfibers (165 ± 44 mg kg.sup.-1 per wash). The similarity between the average width of textile fibers here (12.4 ± 4.5 mum) and those found in ocean samples provides support for the notion that home laundry is an important source of microfiber pollution. Evaluation of two marketed laundry lint traps provided insight into intervention options for the home, with retention of up to 90% for polyester fibers and 46% for nylon fibers. Our observation of a > 850-fold difference in the number of microfibers lost between low and high shedding textiles illustrates the strong potential for intervention, including more sustainable clothing design.
The pollution of the environment with plastics is of growing concern worldwide, including the Arctic region. While larger plastic pieces are a visible pollution issue, smaller microplastics are not ...visible with the naked eye. These particles are available for interaction by Arctic biota and have become a concern for animal and human health. The determination of microplastic properties includes several methodological steps, i.e., sampling, extraction, quantification, and chemical identification. This review discusses suitable analytical tools for the identification, quantification, and characterization of microplastics in the context of monitoring in the Arctic. It further addresses quality assurance and quality control (QA/QC), which is particularly important for the determination of microplastic in the Arctic, as both contamination and analyte losses can occur. It presents specific QA/QC measures for sampling procedures and for the handling of samples in the laboratory, either on land or on ship, and considering the small size of microplastics as well as the high risk of contamination. The review depicts which data should be mandatory to report, thereby supporting a framework for harmonized data reporting.
Microplastics (MPs) were characterized in surficial marine sediment (n = 36) and mussel (n = 29) samples collected along the British Columbia (BC) coast, Canada, using visual identification and ...Fourier Transform Infrared Spectrometry. MPs counts averaged 32.6 ± 5.3 particles per kg in sediment and 0.38 ± 0.04 particles per individual mussel (0.24 ± 0.04 /g of tissue). Victoria Harbour and the North Coast (Prince Rupert area) were MP hotspots, likely resulting from a combination of local sources and oceanographic conditions. Microfibers <1000 μm dominated the pattern in both matrices (61.1 % in sediment; 65.4 % mussels) highlighting the suspected role of textiles in the widespread distribution of MPs in the marine environment. Overall, polyester was dominant in sediment and mussels (54.1 % and 63.5 %, respectively), followed by polyethylene (16.2 % and 11.5 %, respectively). This is the first report of MPs in sediment and mussels along the coast of BC using standardized methods.
•Microplastics averaged 32.6 ± 5.3 particles per kg in sediment.•Microplastics averaged 0.38 ± 0.04 particles per individual mussel.•Victoria Harbour and the North Coast (Prince Rupert area) had high levels of MPs.•Polyester and polyethylene fibers dominated the polymer patterns in both matrices.
We present the strain and temperature dependence of an anomalous nematic phase in optimally doped BaFe2(As, P)2. Polarized ultrafast optical measurements reveal broken fourfold rotational symmetry in ...a temperature range above Tc in which bulk probes do not detect a phase transition. Using ultrafast microscopy, we find that the magnitude and sign of this nematicity vary on a 50–100 μm length scale, and the temperature at which it onsets ranges from 40 K near a domain boundary to 60 K deep within a domain. Scanning Laue microdiffraction maps of local strain at room temperature indicate that the nematic order appears most strongly in regions of weak, isotropic strain. These results indicate that nematic order arises in a genuine phase transition rather than by enhancement of local anisotropy by a strong nematic susceptibility. We interpret our results in the context of a proposed surface nematic phase.
We present the strain and temperature dependence of an anomalous nematic phase in optimally doped BaFe$_2$(As,P)$_2$. Polarized ultrafast optical measurements reveal broken 4-fold rotational symmetry ...in a temperature range above $T_c$ in which bulk probes do not detect a phase transition. Using ultrafast microscopy, we find that the magnitude and sign of this nematicity vary on a ${50{-}100}~\mu$m length scale, and the temperature at which it onsets ranges from 40 K near a domain boundary to 60 K deep within a domain. Scanning Laue microdiffraction maps of local strain at room temperature indicate that the nematic order appears most strongly in regions of weak, isotropic strain. These results indicate that nematic order arises in a genuine phase transition rather than by enhancement of local anisotropy by a strong nematic susceptibility. We interpret our results in the context of a proposed surface nematic phase.
Nonlinear optical properties of materials are useful both for their practical applications, but also as a characterization tool for symmetry in novel systems. However, the nonlinear optical response ...of a material is often not as one of its fundamental properties, along with band structure, linear conductivity, etc. This has particularly been the case with the recent interest in “quantum materials”: materials such as high-Tc superconductors, topological materials, and exotic magnets. Weyl semimetals are a class of materials where band-touching points have divergent Berry curvature, and are host to a number of unique physical phenomena such as the chiral anomaly and Fermi arc surface states. From the nonlinear optics perspective, Weyl semimetals are interesting since inversion-symmetry breaking Weyl semimetals have been experimentally realized, and breaking of inversion-symmetry is crucial for second order nonlinear optical phenomena.In this dissertation, I present results from a number of studies of the Weyl semimetal TaAs and related compounds using nonlinear optical techniques. As detailed here, TaAs was discovered to have the largest measured nonlinear optical susceptibility of any material, and further, this susceptibility was found to be caused by a resonance in the spectrum of nonlinear optical conductivity. TaAs was also measured to have a photogalvanic effect that has qualitatively different characteristics depending on the direction of measurement. These nonlinear optical properties of the TaAs family of materials may lead to interesting applications in near-field nonlinear optics, and optical pulse shaping below the diffraction limit.
We present the strain and temperature dependence of an anomalous nematic phase in optimally doped BaFe_{2}(As,P)_{2}. Polarized ultrafast optical measurements reveal broken fourfold rotational ...symmetry in a temperature range above T_{c} in which bulk probes do not detect a phase transition. Using ultrafast microscopy, we find that the magnitude and sign of this nematicity vary on a 50-100 μm length scale, and the temperature at which it onsets ranges from 40 K near a domain boundary to 60 K deep within a domain. Scanning Laue microdiffraction maps of local strain at room temperature indicate that the nematic order appears most strongly in regions of weak, isotropic strain. These results indicate that nematic order arises in a genuine phase transition rather than by enhancement of local anisotropy by a strong nematic susceptibility. We interpret our results in the context of a proposed surface nematic phase.
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