We investigate the control of the morphological variables on the 2000–2016 glacier‐wide mass balances of 6,470 individual glaciers of High Mountain Asia. We separate the data set into 12 regions ...assumed to be climatically homogeneous. We find that the slope of the glacier tongue, mean glacier elevation, percentage of supraglacial debris cover, and avalanche contributing area all together explain a maximum of 48% and a minimum of 8% of the glacier‐wide mass balance variability, within a given region. The best predictors of the glacier‐wide mass balance are the slope of the glacier tongue and the mean glacier elevation for most regions, with the notable exception of the inner Tibetan Plateau. Glacier‐wide mass balances do not differ significantly between debris‐free and debris‐covered glaciers in 7 of the 12 regions analyzed. Lake‐terminating glaciers have more negative mass balances than the regional averages, the influence of lakes being stronger on small glaciers than on large glaciers.
Key Points
Debris‐free and debris‐covered glaciers have statistically indistinguishable glacier‐wide mass balances over 2000–2016
Lake‐terminating glaciers on average have more negative mass balances than land‐terminating glaciers
Morphological variables explain 8% to 48% of the variance of High Mountain Asia glacier mass balances for the period 2000–2016
The dissolved organic carbon (DOC) leached from two types of microplastics (polyethylene and polypropylene) frequently found in coastal areas were evaluated in situ. Subsequently, the bioavailability ...of leached DOC was assessed for microbial inocula from different coastal communities (i.e., estuarine and open-coastal waters, river-mouth waters and seagrass beds). Leached DOC was largely biodegradable (as much as 85 %). However, seagrass beds and river-mouth waters exhibited lower DOC utilization efficiency than estuarine and open-coastal waters, probably because of differences in their microbial communities. The labile/recalcitrant ratio of DOC leached from plastic was similar under illuminated and dark conditions, whereas DOC leached from polyethylene, rather than DOC leached from polypropylene, was preferentially used by microbial communities. We estimated that as many as 21,000 metric tons of DOC leached from plastics may be released into ocean annually. Our results support the need to consider the potential impacts of coastal plastic pollution on microbial communities, including consideration of the trophic webs and coastal carbon cycle.
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•Dissolved organic carbon (DOC) leached from plastic followed a logarithmic function.•Light rather than salinity affect to DOC leached from plastics.•DOC leached from plastics were greatly biodegradable (as much as 85 %).•Seagrass beds and river-mouth waters exhibited lower DOC utilization efficiency.•Polyethylene-derived DOC was preferential used than polypropylene-derived DOC.
Spectral micro-CT imaging with direct-detection energy discriminating photon counting detectors having small pixel size (< 100×100 µm
) is mainly hampered by: i) the limited energy resolution of the ...imaging device due to charge sharing effects and ii) the unavoidable noise amplification in the images resulting from basis material decomposition. In this work, we present a cone-beam micro-CT setup that includes a CdTe photon counting detector implementing a charge summing hardware solution to correct for the charge-sharing issue and an innovative image processing pipeline based on accurate modeling of the spectral response of the imaging system, an improved basis material decomposition (BMD) algorithm named minimum-residual BMD (MR-BMD), and self-supervised deep convolutional denoising. Experimental tomographic projections having a pixel size of 45×45 µm
of a plastinated mouse sample including I, Ba, and Gd small cuvettes were acquired. Results demonstrate the capability of the combined hardware and software tools to sharply discriminate even between materials having their K-Edge separated by a few keV, such as e.g., I and Ba. By evaluating the quality of the reconstructed decomposed images (water, bone, I, Ba, and Gd), the quantitative performances of the spectral system are here assessed and discussed.
Global (e.g. climate change) and local factors (e.g. nutrient enrichment) act together in nature strongly hammering coastal ecosystems, where seagrasses play a critical ecological role. This ...experiment explores the combined effects of warming, acidification and ammonium enrichment on the seagrass Cymodocea nodosa under a full factorial mesocosm design. Warming increased plant production but at the expense of reducing carbon reserves. Meanwhile, acidification had not effects on plant production but increased slightly carbon reserves, while a slight stimulation of net production and a slight decrease on carbon reserves under ammonium supply were recorded. When all the factors were combined together improved the production and carbon reserves of Cymodocea nodosa, indicating that acidification improved ammonium assimilation and buffered the enhanced respiration promoted by temperature. Therefore, it could indicate that this temperate species may benefit under the simulated future scenarios, but indirect effects (e.g. herbivory, mechanical stress, etc.) may counteract this balance.
•A significant synergy can occur when several environmental factors interact.•Warming positively affect plant production but at expense of reducing carbon reserves.•Loss leaf rates increased with ammonium supply•CO2 increase did not produce significant effects.•Future scenarios may benefit to C. nodosa improving their growth and carbon reserves.
A significant challenge in using thinner and larger crystalline silicon wafers for solar cell manufacture is the reduced yield due to higher wafer breakage rates. At a given process step, wafer/cell ...breakage depends on the stresses produced in the wafer/cell due to prior processing, handling and/or transport and on the presence of structural defects such as cracks. Specifically, analysis of wafer breakage requires knowledge of the total in-plane stress state produced in the wafer due to handling and residual stresses from prior processing. This paper presents a systematic approach to breakage analysis of crystalline silicon wafers during handling via analysis of the total stress state produced in the wafer. The total stress state is determined using a combination of wafer deformation measurements and non-linear finite element analysis. Knowledge of the total stress state in conjunction with the crack size and location enables the determination of wafer breakage and the associated fracture stress. This approach is experimentally validated through breakage tests performed on edge-defined film-fed growth (EFG) wafers with cracks introduced via indentation. The results show that the wafer breakage stress during handling is proportional to the inverse of the square root of the crack length, which is consistent with the linear elastic fracture mechanics theory. The work also confirms the capability of the proposed approach to determine the handling conditions under which wafer/cell breakage will occur.
Western North American (WNA) glaciers outside of Alaska cover 14,384 km2 of mountainous terrain. No comprehensive analysis of recent mass change exists for this region. We generated over 15,000 ...multisensor digital elevation models from spaceborne optical imagery to provide an assessment of mass change for WNA over the period 2000–2018. These glaciers lost 117 ± 42 gigatons (Gt) of mass, which accounts for up to 0.32 ± 0.11 mm of sea level rise over the full period of study. We observe a fourfold increase in mass loss rates between 2000–2009 −2.9 ± 3.1 Gt yr−1 and 2009–2018 −12.3 ± 4.6 Gt yr−1, and we attribute this change to a shift in regional meteorological conditions driven by the location and strength of upper level zonal wind. Our results document decadal‐scale climate variability over WNA that will likely modulate glacier mass change in the future.
Plain Language Summary
Glaciers in western North America provide important thermal and flow buffering to streams when seasonal snowpack is depleted. We used spaceborne optical satellite imagery to produce thousands of digital elevation models to assess recent mass loss for glaciers in western North America outside of Alaska. Our analysis shows that glacier loss over the period 2009–2018 increased fourfold relative to the period 2000–2009. This mass change over the last 18 years is partly explained by changes in atmospheric circulation. Our results can be used for future modeling studies to understand the fate of glaciers under future climate change scenarios.
Key Points
We provide a comprehensive assessment of mass change for western North American (WNA) glaciers excluding those in Alaska
WNA glaciers lost 117 +/‐ 42 gigatons (Gt) of mass over the period 2000‐2018 and could account for 0.32 +/‐ 0.11 mm of sea level rise
Regional changes in glacier mass are partly explained by decadal scale changes in atmospheric circulation
The degenerative effects of multiple sclerosis at the level of the vascular and neuronal networks in the central nervous system are currently the object of intensive investigation. Preclinical ...studies have demonstrated the efficacy of mesenchymal stem cell (MSC) therapy in experimental autoimmune encephalomyelitis (EAE), the animal model for multiple sclerosis, but the neuropathology of specific lesions in EAE and the effects of MSC treatment are under debate. Because conventional imaging techniques entail protocols that alter the tissues, limiting the reliability of the results, we have used non-invasive X-ray phase-contrast tomography to obtain an unprecedented direct 3D characterization of EAE lesions at micro-to-nano scales, with simultaneous imaging of the vascular and neuronal networks. We reveal EAE-mediated alterations down to the capillary network. Our findings shed light on how the disease and MSC treatment affect the tissues, and promote X-ray phase-contrast tomography as a powerful tool for studying neurovascular diseases and monitoring advanced therapies.
Cadiz Bay is a shallow mesotidal lagoon with extensive populations of the seagrass Cymodocea nodosa at intertidal and shallow subtidal elevations. This work aims to understand the mechanisms behind ...the resilience of this species to gradual sea level rise by studying its acclimation capacity to depth along the shallow littoral, and therefore, to gradual variations in the light environment. To address this objective, these populations have been monitored seasonally over a 10 year period, representing the longest seasonal database available in the literature for this species. The monitoring included populations at 0.4, −0.08 and −0.5 m LAT. The results show that C. nodosa has a strong seasonality for demographic and shoot dynamic properties – with longer shoots and larger growth in summer (high temperature) than in winter (low temperature), but also some losses. Moreover, shoots have different leaf morphometry depending on depth, with small and dense shoots in the intertidal areas (0.4 m) and sparse large shoots in the subtidal ones (−0.08 and 0.5 m). These differences in morphometry and shoot dynamic properties, combined with the differences in shoot density, explain the lack of differences in meadow production balance (i.e. meadow growth – meadow losses) between the intertidal (0.4 m) and the deepest population (−0.5 m), supporting the long term resilience of Cymodocea nodosa in Cadiz Bay. This study contributes to the understanding of the mechanisms behind seagrass stability and resilience, which is particularly important towards predicting the effects of climate change on these key coastal ecosystems, and also highlights the value of continuous long-term monitoring efforts to evaluate seagrass trajectories.
•This work presents the longest seasonal database available in literature for Cymodocea nodosa.•C. nodosa acclimates to differences in light availability through morphometric changes.•C. nodosa morphotypes have different growth rate and shoot density.•Morphometric acclimation supports the long-term resilience of C. nodosa meadows in shallow environments.•Water quality and accommodation space are going to be crucial for the adaptation of this species to Sea Level Rise.
Eutrophication is one of the major threats facing seagrasses, promoting effects in different compartments of the community (e.g. plants, epiphytes, fauna). In this study, we researched how in situ ...nutrient enrichment modified the consumption rates of Cymodocea nodosa plants during a period of 3 mo, by creating a set of mesocosm feeding choice experiments with the generalist herbivore Paracentrotus lividus. Nutrient enrichment intensified the consumption of C. nodosa leaves by increasing the palatability of their tissues at different levels. At a first level (i.e. the individual plant response), nutritional quality of the tissues increased (i.e. nitrogen content), while both biomechanical (i.e. absolute force-to-tear, F
TA, and specific force-to-tear, F
TS) and mechanical (i.e. fiber content) traits were reduced. At a second level, the presence of epiphytes coating the leaves increased their nutritional quality without actually increasing their biomechanical resistance, which rendered higher consumption rates. However, the presence of Ulva sp. (a highly palatable macrophyte) reduced the direct consumption of C. nodosa leaves, mainly when coated by epiphytes, a fact fully endorsed by the compensatory feeding theory. Therefore, the nutritional quality of the C. nodosa leaves is a key factor regulating their susceptibility to be consumed, although mechanical and biomechanical factors also gained importance when nutritional quality was low. In addition, the presence of other components of the community (epiphytes and macroalgae) may increase or reduce herbivore pressure, highlighting the complex nature of herbivore–plant interrelationships.
Meteorological studies in high-mountain environments form the basis of our understanding of catchment hydrology and glacier accumulation and melt processes, yet high-altitude (>4000 m above sea ...level, asl) observatories are rare. This research presents meteorological data recorded between December 2012 and November 2013 at seven stations in Nepal, ranging in elevation from 3860 to 5360 m asl. Seasonal and diurnal cycles in air temperature, vapour pressure, incoming short-wave and long-wave radiation, atmospheric transmissivity, wind speed, and precipitation are compared between sites. Solar radiation strongly affects diurnal temperature and vapour pressure cycles, but local topography and valley-scale circulations alter wind speed and precipitation cycles. The observed diurnal variability in vertical temperature gradients in all seasons highlights the importance of in situ measurements for melt modelling. The monsoon signal (progressive onset and sharp end) is visible in all data-sets, and the passage of the remnants of Typhoon Phailin in mid-October 2013 provides an interesting case study on the possible effects of such storms on glaciers in the region.
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