The disposal of tailings in a safe and environmentally friendly manner has always been a challenging issue. The microbially induced carbonate precipitation (MICP) technique is used to stabilise tailings sands. MICP is an innovative soil stabilisation technology. However, its field application in tailings sands is limited due to the poor adaptability of non-native urease-producing bacteria (UPB) in different natural environments. In this study, the ultraviolet (UV) mutagenesis technology was used to improve the performance of indigenous UPB, sourced from a hot and humid area of China. Mechanical property tests and microscopic inspections were conducted to assess the feasibility and the effectiveness of the technology. The roles played by the UV-induced UPB in the processes of nucleation and crystal growth were revealed by scanning electron microscopy imaging. The impacts of elements contained in the tailings sands on the morphology of calcium carbonate crystals were studied with Raman spectroscopy and energy-dispersive X-ray spectroscopy. The precipitation pattern of calcium carbonate and the strength enhancement mechanism of bio-cemented tailings were analysed in detail. The stabilisation method of tailings sands described in this paper provides a new cost-effective approach to mitigating the environmental issues and safety risks associated with the storage of tailings.

The moons of Jupiter and Saturn, such as Europa and Enceladus, are strong candidates for the search for life outside of Earth. Together with the use of direct observational methods, physical and chemical processes that take place on icy moons may be studied on planetary field analogs, that is, on similar reachable locations on Earth. Fieldwork performed on planetary field analogs can test protocols and technology that may be applied on future space missions to extraterrestrial environments. The Arctic is a strong candidate for such studies. This study assesses a spectroscopic protocol for biosignature detection in the Arctic, as a proxy to icy moons. Samples of ice and the water underneath were collected by our team in different locations at and nearby Hudson Bay, Canada, and spectroscopic analysis detected the presence of humic acid in all the samples. On the contrary, biosignatures such as amino acids and beta-carotene may have been present in concentrations below the limit of detection of the equipment used. With proper optimization, it will be possible to implement this simple protocol that relies on lightweight equipment in future space missions to icy moons.

Roadbed engineering in alpine tundra environment is prone to frost heave and thaw settlement, cracking of pavement, uneven settlement, and other challenges under the action of seasonal freeze-thaw cycle. Wicking geotextile has important application value in frost damage control of roadbeds, but solar radiation, especially ultraviolet radiation, is one of the main factors leading to premature failure of wicking geotextile. In this study, different kinds of ultraviolet-resistant wicking fibers were developed by blending modification technology, and the various types of fibers were compared with each other in terms of their physical and mechanical properties, so as to obtain the optimal modified wicking fibers with the content of 2 % UV-1164 + 0.3 % B900 addition. Subsequently, a 20-day accelerated aging test was conducted on modified wicking geotextiles. The inhibitory effect of the modification treatment on the wicking geotextile indicating photo-oxidative aging was characterized by scanning electron microscope, and the effect on the mechanical properties maintenance of the wicking geotextile was characterized by tensile strength and top-breaking strength tests. Finally, a soil column drainage test was designed and carried out, based on which the horizontal hydraulic conductivity rate and 120-h drainage volume of wicking geotextiles before and after the modified treatment were predicted under the aging cycle of 40 d. The test and prediction dates showed that the hydraulic conductivity was deteriorated with the aging time, but the modification treatment could obviously inhibit the deterioration degree. Compared with the control group, the hydraulic conductivity of the modified wicking geotextile increased by about 0.35E-5 g/s, and the drainage capacity increased by 0.76 % at 200 h.

The presence of biodegradable microplastics (BMPs) alongside toxic metals in soil significantly threatens plant health. Current research mainly focuses on the effects of original BMPs. In contrast, the specific impacts of ultraviolet (UV)-aged BMPs and their interaction with Cadmium (Cd) on seed germination and growth are unclear. Therefore, this study incubated aged polylactic acid (PLA) MPs through a UV irradiation aging process and used an indoor hydroponic experiment to systematically investigate the single and combined effects of Cd and BMPs (virgin and aged) on pakchoi (Brassica chinensis L.) germination, photosynthesis, antioxidant systems, and Cd accumulation. The results showed that after 21 days of UV irradiation (UPLA MPs), PLA MPs formed a fractured surface, demonstrating more detrimental effects on pakchoi than virgin ones. UPLA MPs and Cd alone inhibited pakchoi germination, growth, and photosynthesis, while PLA MPs alone promoted these processes. Combined treatment with Cd and UPLA MPs significantly increased oxidative damage and reduced pakchoi root length, chlorophyll, Mg, Mn, and Zn content. Under the combination of Cd and BMPs, PLA MPs could effectively alleviate the toxic effect of Cd on pakchoi. The results unraveled here emphasized that UPLA MPs, especially aged BMPs, could trigger adverse effects on agro-systems with heavy metals. Therefore, the results of this study can provide a new perspective and reference for the ecological risk evaluation of Cd and BMPs pollution in agricultural soils.

Polylactic acid (PLA) is recognized as a promising alternative to traditional petroleum-based plastics due to its excellent biodegradability and well-balanced mechanical properties. Nevertheless, the disadvantages of PLA such as flammability in fire, susceptibility to UV light attack, and slow natural degradation rate limit its application and recovery in high-security areas. In this work, a spherical chitosan-based additive DMPC-Al with mirrorsymmetric internal structure was assembled by layer-by-layer electrostatic reactions, resulting in PLA characterized excellent comprehensive performances. When 7 wt% DMPC-Al was added into PLA, the LOI value of the composite PLA/7DMPC-Al was increased to 29.6%, and UL-94 reached V-0 grade without any molten droplets. The peak heat release rate and total heat release rate were reduced by 13.5% and 16.2%, respectively, and the carbon layer was highly self-expanding. In addition, the UPF of PLA/7DMPC-Al was increased to 34.45 from 0.45 of pure PLA, blocking most of the UV light attacks and extending the service life of PLA. Surprisingly, DMPC-Al actually improved the impact toughness of PLA by 38.5% and facilitated PLA to work continuously when drawing large curved shapes by 3D printing. More importantly, the introduction of DMPC-Al changed the sensitivity of PLA to water and provided sufficient energy for microbial growth, thus accelerating the degradation rate of PLA in the soil under abandoned buildings. This work provides a practical and feasible strategy to achieve multifunctionality of degradable plastics.

We employ nighttime observations from the Lyman Alpha Mapping Project (LAMP) ultraviolet (UV) spectrograph onboard the Lunar Reconnaissance Orbiter to investigate the presence of condensed water ice within lunar south pole cold traps. This study incorporates LAMP observations between 2009 and 2016, which more than doubles the number of observations from previous LAMP Permanently Shadowed Regions (PSRs) studies. In this study, we focus on cold traps within five south polar craters: Faustini, Shoemaker, Haworth, Cabeus, and Amundsen. An unnamed cold trap region adjacent to Haworth and Shoemaker was also investigated. We present On-band (148-162 nm), Edge-band (164-173 nm), and Off-band (175-190 nm) albedo maps at 4-km spatial resolution and far-UV albedo spectra of cold traps at 2-nm spectral resolution. We find Off-band to On-band albedo ratios (the UV wavelength ranges with high and low H2O ice reflectivity, respectively) within cold traps that are consistent with previous PSR studies. Spectral intimate mixture models considering 5 mu m H2O grains and a range of regolith grain sizes (20-74 mu m) with porosities between 0.3 and 0.75 yields abundances of similar to 0.9-4.9 wt.%, where increasing the range of H2O and regolith grain sizes may increase the range of water abundance. We further find generally lower albedos within the cold trap regions than at the surrounding non-cold trap regions across all wavelengths, consistent with increased regolith porosity within cold traps as suggested by Gladstone et al. (2012), .

The PLanetary extreme Ultraviolet Spectrometer (PLUS) is a project funded by the Italian Space Agency focused on the development of an extreme (EUV) and far-ultraviolet (FUV) high-performance spectrograph, which adopts a dual channel optical scheme. Thanks to an optimized layout based on the use of Variable Line Space (VLS) gratings in an off-Rowland configuration, high spectral and spatial resolution are achieved. The efficiency improvement is obtained by the optimization of the coatings on the optical components. Improved detection limit, shorter observations integration time and unprecedented performance in terms of dynamic range will be achieved by the use of high resolution/dynamic range solar blind photon counting detectors. The photon counting detectors will be based on a Micro-Channel Plate (MCP) coupled with an Application Specific Integrated Circuit (ASIC) read out system.

Permanently shadowed regions (PSRs) at the lunar poles are of unique interest for science and exploration due to their low surface temperatures and potential for volatile sequestration. While not directly illuminated by the Sun, PSRs are exposed to faint sources of radiation such as starlight, Lyman alpha photons from the interplanetary medium, and sunlight scattered from the surrounding topography. These illumination sources are significant as they contribute to the thermal energy budget of PSRs, and also provide a photon source with which to observe areas otherwise obscured by shadow. In this work, we survey the illumination conditions from the aforementioned sources within northern and southern hemisphere PSRs at far ultraviolet (FUV), visible (vis) and infrared (IR) wavelengths. With respect to magnitude, it is shown that scattered sunlight is the brightest radiation source to reach the PSRs in the visible and IR spectral regimes. As well, we show that scattered sunlight contributes a considerable supply of FUV photons, and may exceed the interplanetary medium/starlight brightness in many PSR craters due to the temporal and spatial variance of scattered sunlight. This finding suggests a higher rate of photodesorption and lower adsorption residence times for water molecules than previously suggested, and, furthermore, indicates that this rate fluctuates diurnally, seasonally and geographically owing to the variability of the incoming solar flux. Large differences in the received solar energy are found between craters, with crater latitude and size being among the modulating influences. Within individual craters, strong spatial heterogeneities in scattered solar flux are found, with equator-facing PSR slopes receiving 40%-60% of the total energy of slopes oriented toward the pole. Finally, we show that the radiation available is sufficient to detect water ice using vis/FUV or vis/IR filter pairings, and such observations can be made with signal to noise > 10 with an FUV-sensitive camera; however, with more scattered solar photons available for IR imaging, higher signal to noise ratios can be attained with a vis/IR filter pairing.

We calculated the cross sections of photolysis of OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF molecules using quantum chemistry methods. The maximal values for photolysis cross sections of alkali metal monoxides are on the order of 10(-18) cm(2). The lifetimes of photolysis for quiet Sun at 1 astronomical unit are estimated as 2.0 x 10(5), 28, 5, 14, 2.1 x 10(5), 225, 42, 52, 2 x 10(6), 35 400, 486, and 30 400 s for OH, LiO, NaO, KO, HCl, LiCl, NaCl, KCl, HF, LiF, NaF, and KF, respectively. We performed a comparison between values of photolysis lifetimes obtained in this work and in previous studies. Based on such a comparison, our estimations of photolysis lifetimes of OH, HCl, and HF have an accuracy of about a factor of 2. We determined typical kinetic energies of main peaks of photolysis-generated metal atoms. Impact-produced LiO, NaO, KO, NaCl, and KCl molecules are destroyed in the lunar and Hermean exospheres almost completely during the first ballistic flight, while other considered molecules are more stable against destruction by photolysis.

Ozone is known to be present within the surface ice of Jupiter's moon Ganymede as well as Saturn's moons Dione and Rhea. Given the ubiquity of solar photons incident on these water-ice-dominated surfaces, experiments were conducted to better understand the photochemistry of ozone-water ice mixtures. Samples were deposited as thin films in a vacuum chamber under temperature and pressure conditions relevant to satellites in the outer solar system. Chemical changes in the ices were monitored with infrared spectroscopy as they were exposed to ultraviolet light at 116.5/123.6, 147, and 254 nm emitted from Kr, Xe, and Hg resonant lamps, respectively. In all instances, hydrogen peroxide formed after ultraviolet irradiation, while the amount of ozone present decreased. Of the wavelengths tested, irradiation at 254 rim induced the most rapid change both in terms of irradiation time and number of incident photons. This work emphasizes the importance of wavelengths longer than the vacuum ultraviolet in the chemical evolution of ozone on Ganymede, Dione, and Rhea.