Future global SLR network evolution and its impact on the terrestrial reference frame

Satellite laser ranging (SLR) is an important technique that contributes to the determination of terrestrial geodetic reference frames, especially to the realization of the origin and the scale of global networks. One of the major limiting factors of SLR-derived reference frame realizations is the datum accuracy which significantly suffers from the current global SLR station distribution. In this paper, the impact of a potential future development of the SLR network on the estimated datum parameters is investigated. The current status of the SLR network is compared to a simulated potential future network featuring additional stations improving the global network geometry. In addition, possible technical advancements resulting in a higher amount of observations are taken into account as well. As a result, we find that the network improvement causes a decrease in the scatter of the network translation parameters of up to 24%, and up to 20% for the scale, whereas the technological improvement causes a reduction in the scatter of up to 27% for the translations and up to 49% for the scale. The Earth orientation parameters benefit by up to 15% from both effects.     

Quantification of particle-induced inflammatory stress response: a novel approach for toxicity testing of earth materials

Background

Reactive oxygen species (ROS) are vital regulators of many cellular functions in the body. The intracellular ROS concentration is highly regulated by a balance between pro-oxidants and anti-oxidants. A chronic excess of pro-oxidants leads to elevated ROS concentrations and inflammation, possibly initiating or enhancing disease onset. Mineral-induced generation of ROS, the role of minerals in upregulating cellular ROS, and their role in the development of several occupational diseases are now widely recognized. However, there is no standard protocol to determine changes in ROS production in cells after exposure to mineral dust or earth materials in general. In this study, a new method for determining the degree of cellular toxicity (i.e., cytotoxicity) of particles is described that will help bridge the gap in knowledge.

Results

By measuring the production of ROS and the viability of cells, an inflammatory stress response (ISR) indicator is defined. This approach normalizes the ROS upregulation with respect to the number of viable cells at the time of measurement. We conducted experiments on a series of minerals and soils that represent materials that are inert (i.e., glass beads, anatase, and a soil with low trace element content), moderately reactive (i.e., soil with high trace element content), and highly reactive (i.e., pyrite). Inert materials generated the lowest ISR, averaging 350% compared to the control. Acid washed pyrite produced the highest ISR (1,100 fold higher than the control). The measurements conducted as a function of time showed a complex response. Most materials showed an increase in ISR with particle loading.

Conclusions

The amount of cellularly generated ROS and cell viability combined provide a better understanding of particle-induced oxidative stress. The results indicate that some earth materials may solicit an initial burst of ROS, followed by a second phase in which cell viability decreases and ROS production increases, leading to a high ISR value. Hence, measurements conducted over a range of particle loading combined with multiple data measurements up to 24 hours can provide new insights in the possible effect of exposure to earth materials on human health.     

Quartz Reference Materials for Oxygen Isotope Analysis by SIMS

Two quartz samples of igneous origin, UNIL‐Q1 (Torres del Paine Intrusion, Chile) and BGI‐Q1 (Shandong province, China), were calibrated for their oxygen isotope composition for SIMS measurements. UNIL‐Q1 and BGI‐Q1 were evaluated for homogeneity using SIMS. Their reference δ¹⁸O values were determined by CO₂ laser fluorination. The average δ¹⁸O value found for UNIL‐Q1 is 9.8 ± 0.06‰ and that for BGI‐Q1 is 7.7 ± 0.11‰ (1s). The intermediate measurement precision of SIMS oxygen isotope measurements was 0.32–0.41‰ (2s; UNIL‐Q1) and 0.40–0.48‰ (2s; BGI‐Q1), respectively. While less homogeneous in its oxygen isotope composition, BGI‐Q1 is also suitable for SIMS trace element measurements.     

Barium, SiO2 (excess), and P2O5 as proxies of biological productivity in the Middle East during the Palaeocene and the latest Palaeocene benthic extinction event

The distribution of barium and other elements related to biological productivity has been studied in two Palaeocene sections from the Middle East. In the bathyal Ben Gurion section, Israel, Ba* (= Ba/Al₂O₃× 15%) concentrations are low, in the range 0.04% to 0.3% in the lower Palaeocene, and very high, 1% to 2%, throughout most of the upper Palaeocene. In the neritic Gebel Aweina section in Egypt Ba* values are low, < 0.1%, throughout the entire Palaeocene. The Ba* enrichments at Ben Gurion and their correlations with increases in P₂O₅ and opaline silica, and local and global δ¹³C maxima, indicate that upwelling and high productivity were important in this region during the late Palaeocene. The absence of Ba* enrichments in the shallower Gebel Aweina section probably reflects the strong depth dependence of biobarium deposition. In the uppermost Palaeocene, at the level where the global benthic extinction event is registered, Ba* concentrations in the Ben Gurion section increase to anomalous 6%. which suggests that upwelling and possibly wind strengths intensified during this event. The results speak against deep-water formation in this region since downwelling and not upwelling is required.     

Protection of architectural heritage: attitudes of local residents and visitors in Sirako,Greece

Architectural heritage comprises one of the most important elements of mountain settlements in Greece. It holds high cultural value, represents the tangible continuation of the past and forms the unique character and identity of each mountain region. Yet, controversy regarding funding for its preservation often arises. In this paper, we used two Contingent Valuation surveys to estimate the social benefit deriving from protecting the traditional architecture in the mountainous village of Sirako and, through it, to examine perceptions and attitudes of local residents and visitors. Research findings revealed a strong social will in favor of the good’s protection followed by high percentages of positive willingness to pay (WTP). However, WTP is significantly higher among residents. Cultural heritage value, of the good, appears to prevail, along with the environmental one. However, both residents and visitors pointed out that local heritage, if well-preserved, will boost tourism development. Residents appeared to better recognize the true level of architectural decay, expressed higher apprehension for its protection and were willing to pay higher amount of money. Tourists, on the other side, expressed high satisfaction for their visit, appreciated the beauty and serenity emerging from local built and natural environment and spent several days visiting the surrounding area. The longer they stayed and got familiar with the village, the more willing they were to contribute to local heritage’s protection. Percentages reflecting indifference for protecting architecture were extremely low. Yet, they were higher among tourists. Traditional architecture is considered as public good; an opinion resulting in an important percentage of visitors stating that national government should provide the necessary funding. In addition, the architecture appears to hold a high level of topicality. Those descending from Sirako or emotionally connected to it, of both social groups, turned out to be more concerned about the good and with a stronger sense of responsibility for it. Use-value of the good holds high economic value, as well, while higher percentages of zero WTP appeared among non-users. Research findings revealed social attitudes and perceptions on what constitutes architectural heritage, in its cultural and economic frame. If taken under consideration, they may form useful drivers for local, heritage-based, sustainable development.     

Living Shorelines Support Nearshore Benthic Communities in Upper and Lower Chesapeake Bay

Human population growth and sea-level rise are increasing the demand for protection of coastal property against shoreline erosion. Living shorelines are designed to provide shoreline protection and are constructed or reinforced using natural elements. While living shorelines are gaining popularity with homeowners, their ability to provide ecological services (e.g., habitat provision and trophic transfer) is not well understood, and information is needed to improve coastal and resource management decision-making. We examined benthic community responses to living shorelines in two case-study subestuaries of Chesapeake Bay using a before-after control-impact study design. At Windy Hill, a bulkhead was removed and replaced by three tombolos, sand fill, and native marsh vegetation. At Lynnhaven, 25 m of eroding marsh shoreline was stabilized with coir logs, sand fill, and native marsh vegetation. Communities of large (>?3 mm) infauna adjacent to living shorelines at both locations tended to increase in biomass by the end of the study period. Community compositions changed significantly following living shoreline construction at Windy Hill, reflecting a trend toward higher density and biomass of large bivalves at living shorelines compared to pre-construction. Increasing trends in density and biomass of clams and simultaneously decreasing density and decreasing trends in biomass of polychaetes suggest a transition toward stable infaunal communities at living shorelines over time, though longer-term studies are warranted.     

The influence of leaf litter diversity and soil fauna on initial soil erosion in subtropical forests

Although the protective role of leaf litter cover against soil erosion is known for a long time, little research has been conducted on the processes involved. Moreover, the impact of soil meso‐ and macrofauna within the litter layer on erosion control is not clear. To investigate how leaf litter cover and diversity as well as meso‐ and macrofauna influence sediment discharge in subtropical forest ecosystems, a field experiment has been carried out in Southeast China. A full‐factorial random design with 96 micro‐scale runoff plots and 7 domestic leaf species was established and erosion was triggered by a rainfall simulator. Our results demonstrate that leaf litter cover protects soil from erosion (?82 % sediment discharge on leaf covered plots) by rainfall and this protection is removed as litter decomposes. The protective effect is influenced by the presence or absence of soil meso‐ and macrofauna. Fauna presence increases soil erosion rates significantly by 58 %, while leaf species diversity shows a non‐significant negative trend. We assume that the faunal effect arises from arthropods slackening and processing the soil surface as well as fragmenting and decomposing the protecting leaf litter covers. Even though the diversity level did not show a significant influence, single leaf species in monocultures show rather different impacts on sediment discharge and thus, erosion control. In our experiment, runoff plots with leaf litter from Machilus thunbergii showed the highest sediment discharge (68.0 g m^?2) whereas plots with Cyclobalanopsis glauca showed the smallest rates (7.9 g m^?2). Copyright © 2015 John Wiley & Sons, Ltd.     

How rapidly do neutron stars spin at birth? Constraints from archival X-ray observations of extragalactic supernovae

Traditionally, studies aimed at inferring the distribution of birth periods of neutron stars are based on radio surveys. Here we propose an independent method to constrain the pulsar spin periods at birth based on their X-ray luminosities. In particular, the observed luminosity distribution of supernovae (SNe) poses a constraint on the initial rotational energy of the embedded pulsars, via the     correlation found for radio pulsars, and under the assumption that this relation continues to hold beyond the observed range. We have extracted X-ray luminosities (or limits) for a large sample of historical SNe observed with Chandra , XMM and Swift , which have been firmly classified as core-collapse SNe. We have then compared these observational limits with the results of Monte Carlo simulations of the pulsar X-ray luminosity distribution for a range of values of the birth parameters. We find that a pulsar population dominated by millisecond periods at birth is ruled out by the data.     

Major and trace element characterization of tephra layers offshore Pantelleria Island: insights into the last 200 ka of volcanic activity and contribution to the Mediterranean tephrochronology

A detailed tephrochronological study was carried out on the deep‐sea core collected from Site 963A in the Sicily Channel during ODP Leg 160. The chronology of the succession is provided by an age–depth model based on isotope stratigraphy and quantitative eco‐biostratigraphy. Major, trace and rare earth element content was obtained on single glass grains through electron probe micro‐analysis and laser ablation–inductively coupled plasma mass spectrometry techniques from six well‐preserved tephra layers, characterized by a discrete thickness found along the succession. These deposits were correlated with the volcanic activity of Pantelleria and dated at 42.5, 127.5, 128.1, 129.1, 188.7 and 197.7 ka. This detailed chemical characterization of the studied deposits aims to provide a valuable reference database for scientists working on both proximal and distal products erupted at Pantelleria island during the Late Pleistocene. This study, moreover, offers the opportunity to better identify Pantelleria‐related marker tephras within the tephrochronological framework of the central and eastern Mediterranean area. Copyright © 2012 John Wiley & Sons, Ltd.     

Climate sensitivity of water use by riparian woodlands at landscape scales

Semi-arid riparian woodlands face threats from increasing extractive water demand and climate change in dryland landscapes worldwide. Improved landscape-scale understanding of riparian woodland water use (evapotranspiration, ET) and its sensitivity to climate variables is needed to strategically manage water resources, as well as to create successful ecosystem conservation and restoration plans for potential climate futures. In this work, we assess the spatial and temporal variability of Cottonwood (Populus fremontii)-Willow (Salix gooddingii) riparian gallery woodland ET and its relationships to vegetation structure and climate variables for 80 km of the San Pedro River corridor in southeastern Arizona, USA, between 2014 and 2019. We use a novel combination of publicly available remote sensing, climate and hydrological datasets: cloud-based Landsat thermal remote sensing data products for ET (Google Earth Engine EEFlux), Landsat multispectral imagery and field data-based calibrations to vegetation structure (leaf-area index, LAI), and open-source climate and hydrological data. We show that at landscape scales, daily ET rates (6–10 mm day⁻¹) and growing season ET totals (400–1,400 mm) matched rates of published field data, and modelled reach-scale average LAI (0.80–1.70) matched lower ranges of published field data. Over 6 years, the spatial variability of total growing season ET (CV = 0.18) exceeded that of temporal variability (CV = 0.10), indicating the importance of reach-scale vegetation and hydrological conditions for controlling ET dynamics. Responses of ET to climate differed between perennial and intermittent-flow stream reaches. At perennial-flow reaches, ET correlated significantly with temperature, whilst at intermittent-flow sites ET correlated significantly with rainfall and stream discharge. Amongst reaches studied in detail, we found positive but differing logarithmic relationships between LAI and ET. By documenting patterns of high spatial variability of ET at basin scales, these results underscore the importance of accurately accounting for differences in woodland vegetation structure and hydrological conditions for assessing water-use requirements. Results also suggest that the climate sensitivity of ET may be used as a remote indicator of subsurface water resources relative to vegetation demand, and an indicator for informing conservation management priorities.