Mercury: Absence of crystalline Fe2+ in the regolith

Reflectance spectra of terrain on Mercury containing both smooth plains and intercrater plains were obtained using a charge-coupled device spectrograph on 24 November 1984. The composite spectrum covers the 0.53- to 1.02-μm spectral range with a resolution of 17 Å. Absorption features due to telluric H₂O absorption are clearly mapped around 0.73, 0.82, and 0.93 μm. No evidence exists in the new spectrum for the proposed orthopyroxene absorption centered near 0.9 μm seen in older spectra of this terrain. The surface material is probably highly reduced, with any iron present in metallic form. Based upon the new spectrum, a history of heavy micrometeoroid bombardment of the Mercurian surface is suggested, resulting in a surface regolith primarily comprised of agglutinates.     

Benthic macrofauna–habitat associations in Willapa Bay, Washington, USA

Estuary-wide benthic macrofauna–habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [Crassostrea gigas], bare mud/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2 dominants, a fanworm, Manayunkia aestuarina, in Spartina, and a sand dollar, Dendraster excentricus, in subtidal, were rare or absent in all other habitats. Benthic macrofaunal Bray–Curtis similarity varied among all habitats except eelgrass and oyster. There were significant differences among habitats within- and between-years on several of the following ecological indicators: mean number of species (S), abundance (A), biomass (B), abundance of deposit (AD), suspension (AS), and facultative (AF) feeders, Swartz's index (SI), Brillouin's index (H), and jackknife estimates of habitat species richness (HSR). In the 4 habitats sampled in both years, A was about 2.5× greater in 1996 (a La Niña year) than 1998 (a strong El Niño year) yet relative values of S, A, B, AD, AS, SI, and H among the habitats were not significantly different, indicating strong benthic macrofauna–habitat associations despite considerable climatic and environmental variability. In general, the rank order of habitats on indicators associated with high diversity and productivity (high S, A, B, SI, H, HSR) was eelgrass = oyster ≥ Atlantic cordgrass ≥ mud shrimp ≥ bare mud/sand ≥ ghost shrimp = subtidal. Vegetation, burrowing shrimp, and oyster density and sediment %silt + clay and %total organic carbon were generally poor, temporally inconsistent predictors of ecological indicator variability within habitats. The benthic macrofauna–habitat associations in this study can be used to help identify critical habitats, prioritize habitats for environmental protection, index habitat suitability, assess habitat equivalency, and as habitat value criteria in ecological risk assessments in Willapa Bay.     

Welcome to Woodside: Inverbrackie Alternative Place of Detention and performances of belonging in Woodside,South Australia,and Australia

Alternative Places of Detention (APODs) are a new way of detaining asylum seekers in Australia. The establishment of APODs creates a new formal structure of belonging in Australia which challenges everyday practices of belonging and senses of belonging at the local and national scale. This paper examines practices of belonging which emerged following the establishment of the Inverbrackie APOD in Woodside, South Australia. Using a critical discourse analysis approach, informed by the insights of theories of performativity, this research explores the competing stories of two broadly defined groups (opponents and supporters of Inverbrackie) engaged in a dialogue about asylum seekers, refugees, immigration detention and belonging. While opposition to the APOD was vocal and frequent in the lead-up to the establishment of the detention centre, once the Inverbrackie APOD became operational opponents’ voices began to fade. On the other hand, supporters continued to say things—and more importantly continued to do things—to nurture belonging for asylum seekers in Inverbrackie, Woodside, and Australia.     

Magmatic fluids of Tatun volcanic group,Taiwan

Two distinctive magmatic fluids were recognized in the Tatun volcanic group (TVG), Taiwan. One is a relatively reduced fluid represented by the fumarolic gases at Hsiao-you-ken (HYK) geothermal field. Another is an oxidized fluid containing high concentrations of HCl represented by the fumarolic gases at Da-you-ken (DYK). An intermediate gas was recognized at Gung-tze-ping (GTP) and She-hung-ping (SHP). The fumarolic gases at HYK and GTP possess the features of so-called primary steam generated on mixing of magmatic gas and meteoric groundwater. The fumarolic gases at DYK are a simple mixture between magmatic gas and water vapor of meteoric origin. The CO₂/H₂O molar ratio of the magmatic component in the fumarolic gases at DYK was estimated to be 0.018, meanwhile it was estimated to be 0.027 for the fumarolic gases at HYK and GTP, suggesting the magma beneath DYK is depleted in volatiles relative to the magma beneath HYK and GTP. The estimated CO₂/H₂O ratio for the magmatic component is comparable to that of some active volcanoes in Japan, suggesting the enrichment of volatiles in the magmas beneath TVG.     

The dependence of reflectance spectra of Mercury on surface terrain

Reflectance spectra of Mercury, covering the spectral range of ～0.3–1.1 μm obtained during 1963–1976, were examined for any correlations with surface terrain. Mercury's 6.1385°/day rotational rate, the phases of the planet around maximum elongations, and bidirectional reflectance spectroscopy theory were used to identify the surface area associated with each spectrum. Data from 1974–1975, re-reduced with improved standard star flux ratios, show a weak absorption band in the near infrared not see in earlier analyses. Older spectra suggest that the western longitudes of the unimaged side of Mercury are similar to the rest of the planet. Spectra of the intercrater plains in the 0–90° quadrant suggest a possible absorption band. Spectra of areas dominated by Caloris Basin with the encompassing smooth plains may show Fe²⁺ abundances in the soil comparable to lunar highlands soil. No striking differences between spectra of intercrater plains and spectra of smooth plains are found. The absorption features seen in spectra of Mercury are generally weaker than features seen in lunar spectra.     

Recurrent spring‐fed rivers in a Middle to Late Pleistocene semi‐arid grassland: Implications for environments of early humans in the Lake Victoria Basin,Kenya

The effect of changing palaeoclimate and palaeoenvironment on human evolution during the Pleistocene is debated, but hampered by few East African records directly associated with archaeological sites prior to the Last Glacial Maximum. Middle to Late Pleistocene deposits on the shoreline of eastern Lake Victoria preserve abundant vertebrate fossils and Middle Stone Age arte‐facts associated with riverine tufas at the base of the deposits, which are ideal for palaeoenvironmental reconstructions. New data from tufas identified on Rusinga Island and on the mainland near Karungu, Kenya are provided from outcrop, thin sections, mineralogical, stable isotopic and U‐series dating analyses. Tufa is identified in four sites: Nyamita (94·0 ± 3·3 and 111·4 ± 4·2 ka); Kisaaka, Aringo (455 ± 45 ka); and Obware. The age ranges of these tufa deposits demonstrate that spring‐fed rivers were a recurrent, variably preserved feature on the Pleistocene landscape for ca 360 kyr. Poor sorting of clastic facies from all sites indicates flashy, ephemeral discharge, but these facies are commonly associated with barrage tufas, paludal environments with δ¹³C values of ca 10‰ indicative of C₃ plants and fossil Hippopotamus, all of which indicate a perennial water source. Other tufa deposits from Nyamita, Obware and Aringo have a mixed C₃/C₄ signature consistent with a semi‐arid C₄ grassland surrounding these spring‐fed rivers. The δ¹⁸O values of tufa from Nyamita are on average ca 1‰ more negative than calcite precipitated from modern rainfall in the region, suggesting greater contribution of depleted monsoonal input, similar to the Last Glacial Maximum. Microdebitage and surface‐collected artefacts indicate that early modern humans were utilizing these spring‐fed rivers. The presence of spring?fed rivers would have afforded animals a reliable water source, sustaining a diverse plant and animal community in an otherwise arid environment.     

Measurements of Faraday Rotation Through the Solar Corona During the 2009 Solar Minimum with the MESSENGER Spacecraft

Measurements of Faraday rotation through the solar corona were collected using the radio beacon aboard the MESSENGER spacecraft during the longest solar minimum in a century. As MESSENGER entered superior conjunction, the plane of polarization of its radio signal was observed to rotate as it traversed the circularly birefringent plasma of the Sun’s atmosphere. On time scales of less than three hours, these uncalibrated plane of polarization observations of Faraday rotation can be used to investigate the dynamic processes in the solar plasma, such as magnetohydrodynamic (MHD) waves and coronal mass ejections (CMEs). Here we describe the MESSENGER Faraday rotation experiment, the data processing conducted to obtain the plane of polarization, and the estimation of error.     

Optimal benthic macrofaunal sampling protocol for detecting differences among four habitats in Willapa Bay,Washington, USA

As part of an effort to estimate estuarine habitat values with respect to ecological indicators of benthic macrofaunal community condition, an optimal (effective and least costly) sampling protocol (sample unit size [area x depth], sieve mesh size, and sample number [n]) was determined. The goal was to use four ecological indicators (number of species, abundance, biomass, and fish and crab prey abundance) to detect differences among four intertidal habitats in Willapa Bay, Washington, United States. The four habitats were eelgrass (Zostera marina), Atlantic cordgrass (Spartina alterniflora), mud shrimp (Upogebia pugettensis), and ghost shrimp (Neotrypaea californiensis). Four sample unit areas (0.005, 0.010, 0.015, and 0.020 m²), two sample unit depths (0–5 and 0–10 cm), and two sieve mesh sizes (1.0 and 0.5 mm) were evaluated. The optimal sampling protocol was defined as the least costly protocol capable of reliably (statistical power, 1?β≥0.80) detecting significant (α=0.05) differences among ≥4 of the 6 pairwise habitat contrasts by ANOVA on all four ecological indicators. The relative cost of each sampling protocol was estimated as a direct function of the sample unit size and number and the cost-in-processing-time ratios of 1 (5 cm deep):1.7 (10 cm deep) and 1 (≥1.0 mm macrofauna size fraction); 2.5 (≥0.5 mm macrofauna size fraction), which were taken from previous studies. The optimal sampling protocol was 15–20, 0.01-m²×5-cm deep, 0.5-mm mesh samples per habitat.