RESUMEN

Microplastics (MPs) are emerging pollutants that interact extensively with dissolved organic matter (DOM) and this influences the environmental behavior of MPs in aqueous ecosystems. However, the effect of DOM on the photodegradation of MPs in aqueous systems is still unclear. The photodegradation characteristics of polystyrene microplastics (PS-MPs) in an aqueous system in the presence of humic acid (HA, a signature compound of DOM) under ultraviolet light conditions were investigated in this study through Fourier transform infrared spectroscopy coupled with two-dimensional correlation analysis, electron paramagnetic resonance, and gas chromatography-mass spectrometry (GC/MS). HA was found to promote higher levels of reactive oxygen species (0.631 mM of ▪OH), which accelerated the photodegradation of PS-MPs, with a higher degree of weight loss (4.3%), higher level of oxygen-containing functional groups, and lower average particle size (89.5 µm). Likewise, GC/MS analysis showed that HA contributed to a higher content of oxygen-containing compounds (42.62%) in the photodegradation of PS-MPs. Moreover, the intermediates and final degradation products of PS-MPs with HA were significantly different in the absence of HA during 40 days of irradiation. These results provide an insight into the co-existing compounds on the degradation and migration processes of MP and also support further research toward the remediation of MPs pollution in aqueous ecosystems.

Asunto(s)

Microplásticos , Contaminantes Químicos del Agua , Poliestirenos/química , Plásticos , Rayos Ultravioleta , Sustancias Húmicas/análisis , Ecosistema , Materia Orgánica Disuelta , Contaminantes Químicos del Agua/análisis , Oxígeno/análisis

RESUMEN

Conventional solar adaptive optics uses one deformable mirror (DM) and one guide star for wave-front sensing, which seriously limits high-resolution imaging over a large field of view (FOV). Recent progress toward multiconjugate adaptive optics indicates that atmosphere turbulence induced wave-front distortion at different altitudes can be reconstructed by using multiple guide stars. To maximize the performance over a large FOV, we propose a solar tomography adaptive optics (TAO) system that uses tomographic wave-front information and uses one DM. We show that by fully taking advantage of the knowledge of three-dimensional wave-front distribution, a classical solar adaptive optics with one DM can provide an extra performance gain for high-resolution imaging over a large FOV in the near infrared. The TAO will allow existing one-deformable-mirror solar adaptive optics to deliver better performance over a large FOV for high-resolution magnetic field investigation, where solar activities occur in a two-dimensional field up to 60'', and where the near infrared is superior to the visible in terms of magnetic field sensitivity.

RESUMEN

We describe a fully symmetric nulling coronagraph for single-aperture telescopes that is based on a rotational shearing interferometer (RSI) and that is intended for the imaging of faint companions to nearby bright stars. In the proposed layout, all asymmetries inherent in previous single-aperture RSI-based nulling coronagraphs have been eliminated, and the bright and dark outputs are both accessible. As a resulty deep, broadband, dual-polarization rejection of on-axis starlight should be possible with this system.