The magnitude and albedo of Mars

A comprehensive set of magnitudes obtained between 1954 and 2006 are analyzed. The martian brightness and its variations are characterized empirically at UBVRI wavelengths. Geometrical factors including phase angle, orbital longitude and rotation angle are distinguished from geophysical factors including dust storms and changing albedo features. The phase function indicates a brightness surge near opposition at all wavelengths except possibly in the U band. The color indices reveal increased reddening with phase angle. No significant brightness difference between morning and evening hemisphere observations is indicated with the possible exception of the I band. There is no conclusive evidence for inter-annual brightness variation during the years from 1991 to 2006 when abundant photometry is available. Major dust storms caused brightness excesses that were strongest in the R band at an average of 0.15 mag more luminous than the empirical model for dust-free conditions. The storm of 2001 produced a rapid increase at the onset followed by a slower decline, while the 2003–2004 event show a more gradual increase. The return to normal brightness was linear in magnitude for both storms. Brightness excesses at longer wavelengths were about 0.20 to 0.25 mags at the peak of the 2001 storm. The observed geometric albedo of Mars is 0.059±0.001 in U, 0.089±0.001 in B, 0.170±0.002 in V, 0.289±0.003 in R, and 0.330±0.003 in I. The corresponding albedo values for all five colors exceed those recorded in the literature, with larger percentage increases at shorter wavelengths.     

Auriacusite, Fe3+Cu2+AsO4O, the first M 3+ member of the olivenite group, from the Black Pine mine, Montana, USA

Auriacusite, ideally Fe³⁺Cu²⁺AsO₄O, is a new arsenate mineral (IMA2009–037) and the Fe³⁺ analogue of olivenite, from the Black Pine mine, 14.5 km NW of Philipsburg, Granite Co., Montana, USA. It occurs lining quartz vughs and coating quartz crystals and is associated with segnitite, brochantite, malachite, tetrahedrite and pyrite. Auriacusite forms fibrous crystals up to about 5?µm in width and up to about 100?µm in length, which are intergrown to form fibrous mats. Individual crystals are a brownish golden yellow, whilst the fibrous mats are ochreous yellow. The crystals have a silky lustre and a brownish yellow streak. Mohs hardness is about 3 (estimated). The fracture is irregular and the tenacity is brittle. Auriacusite crystals are biaxial (+), with α?=?1.830(5), β?=?1.865(5) and γ?=?1.910(5), measured using white light, and with 2V _meas.?=?83(3)º and 2V _calc. = 84.6º. Orientation: X?=?a, Y?=?c, Z?=?b. Crystals are nonpleochroic or too weakly so to be observed. The empirical formula (based on 5 O atoms) is (Fe _1.33 ³⁺ Cu_0.85Zn_0.03)_Σ2.21(As_0.51Sb_0.27Si_0.04?S_0.02Te_0.01)_Σ0.85O₅. Auriacusite is orthorhombic, space group Pnnm, a?=?8.6235(7), b?=?8.2757(7), c?=?5.9501(5) Å, V?=?424.63(6) ų, Z?=?4. The five strongest lines in the powder X-ray diffraction pattern are [d _obs in Å / (I) / hkl]: 4.884 / (100) / 101, 001; 2.991 / (92) / 220; 2.476 / (85) / 311; 2.416 / (83) / 022; 2.669 / (74) / 221. The crystal structure was solved from single-crystal X-ray diffraction data utilising synchrotron radiation and refined to R ₁?=?0.1010 on the basis of 951 unique reflections with F _o?>?4σF. Auriacusite is identified as a member of the olivenite group with Fe³⁺ replacing Zn²⁺ or Cu²⁺ in trigonal bipyramidal coordination. Evidence suggests that auriacusite is an intermediate member between olivenite and an as yet undescribed Fe³⁺Fe³⁺-dominant member. The name is derived from the Latin auri (golden yellow) and acus (needle), in reference to its colour and crystal morphology.     

An occurrence of cadmiferous phosphorite soil concretions in Jamaica

Bauxite exploration drilling revealed the presence of phosphate minerals through the chemical and XRD analysis of recovered drill hole samples at Spitzbergen, in Manchester Parish, Jamaica. A subsequent pit led to the discovery of phosphorite concretions composed of hard competent masses of finely crystalline fluorapatite, with some minor crandallite. The phosphorite contains anomalously high levels of Zn (>5000 mg kg⁻¹), Cd (>1.1%), Ag (>20 mg kg⁻¹), Be (>80 mg kg⁻¹) and, to a lesser extent, U. Textural and geochemical evidence indicates that the phosphorite concretions were most likely formed by the replacement of limestone by secondary deposition proximal to fossil guano deposits, postulated to be Late Miocene or Pliocene sea-bird colonies. Mechanical dispersion of the phosphorite concretions through karst weathering processes has led to their wider spatial distribution than the original guano deposits. Subsequent weathering of the concretions and the admixture of their decomposition products into the bauxitic and Terra Rossa soils is postulated to be the cause of the widespread anomalous levels of Zn, Cd and Be in these soils in central Jamaica, and the elevated levels of P in the bauxite.     

Formation of the Vysoká–Zlatno Cu–Au skarn–porphyry deposit, Slovakia

The central zone of the Miocene Štiavnica stratovolcano hosts several occurrences of Cu–Au skarn–porphyry mineralisation, related to granodiorite/quartz–diorite porphyry dyke clusters and stocks. Vysoká–Zlatno is the largest deposit (13.4 Mt at 0.52% Cu), with mineralised Mg–Ca exo- and endoskarns, developed at the prevolcanic basement level. The alteration pattern includes an internal K- and Na–Ca silicate zone, surrounded by phyllic and argillic zones, laterally grading into a propylitic zone. Fluid inclusions in quartz veinlets in the internal zone contain mostly saline brines with 31–70 wt.% NaCl eq. and temperatures of liquid–vapour homogenization (Th) of 186–575°C, indicating fluid heterogenisation. Garnet contains inclusions of variable salinity with 1–31 wt.% NaCl eq. and Th of 320–360°C. Quartz–chalcopyrite veinlets host mostly low-salinity fluid inclusions with 0–3 wt.% NaCl eq. and Th of 323–364°C. Data from sphalerite from the margin of the system indicate mixing with dilute and cooler fluids. The isotopic composition of fluids in equilibrium with K-alteration and most skarn minerals (both prograde and retrograde) indicates predominantly a magmatic origin (δ¹⁸O_fluid 2.5–12.3‰) with a minor meteoric component. Corresponding low δD_fluid values are probably related to isotopic fractionation during exsolution of the fluid from crystallising magma in an open system. The data suggest the general pattern of a distant source of magmatic fluids that ascended above a zone of hydraulic fracturing below the temperature of ductile–brittle transition. The magma chamber at ∼5–6 km depth exsolved single-phase fluids, whose properties were controlled by changing PT conditions along their fluid paths. During early stages, ascending fluids display liquid–vapour immiscibility, followed by physical separation of both phases. Low-salinity liquid associated with ore veinlets probably represents a single-phase magmatic fluid/magmatic vapour which contracted into liquid upon its ascent.     

Groundwater contributions of flow and nitrogen in a headwater agricultural watershed

Nonpoint sources of nitrogen (N) and other nutrients are a major source of water pollution within the Chesapeake Bay watershed and other basins around the world. Human activities associated with agricultural practices can account for a large percentage of N loadings delivered to streams and rivers. This work aims to improve understanding of N transport from groundwater to surface waters, quantifying the principal hydrological processes driving water and N fluxes into and out of a headwater agricultural stream reach. The study site is a 175-m stream reach in a heavily cultivated 40-ha watershed in east-central Pennsylvania. This subwatershed is underlain by fractured shale bedrock, and receives most of its baseflow from groundwater, either by diffuse matrix discharge through the streambed or by localized discharge through riparian seeps. Samples of stream, seep, and shallow groundwater were collected approximately monthly under steady hydrologic conditions in 2017. Calculated matrix flow from hydraulic head and conductivity measurements paired with differential stream gauging was used to solve for the riparian seep flux using a mass balance approach. Riparian seep fluxes ranged from 45 to 217 m³/d, transporting 0.6–4.2 kg N d⁻¹ of nitrate-N from the fractured bedrock aquifer to the stream. Hydrochemical data suggest that the stream is mainly disconnected from the underlying aquifer and that seeps supply essentially all water and N to the system. Seeps are likely sourced with N in nearby agricultural fields and accelerated through the system with shorter residence times than shallow groundwater. Water isotope data reinforced this notion. This study underscores the importance of agriculture as a source of N to ground and surface waters. Identifying source areas that are causing groundwater enrichment of N and seep areas where N discharges to streams is beneficial for developing N pollution mitigation strategies and implementing management practices that aim to reduce nutrient loads to the Chesapeake Bay.     

Genotyping of Rhodopirellula baltica organisms using multispacer sequence typing

Rhodopirellula baltica is a ubiquitous Planctomycetes organism isolated from marine environments worldwide. Multilocus sequence analysis (MLSA) has been the only method used to assess the diversity of R. baltica organisms. Here, we developed multispacer sequence typing (MST) genotyping and applied it to four R. baltica isolates from the French Mediterranean Sea and R. baltica DSM10527^T type strain. While MLSA yielded interpretable sequences for two of nine genes in three R. baltica isolates, MST based on sequencing two intergenic spacers yielded an unambiguous, strain‐specific profile for each one of the four R. baltica isolates under investigation. We propose that MST could be used as an alternative R. baltica genotyping method to assess the diversity of these Planctomycetes organisms.     

Use of Federal Sand for Beach Nourishment and Shore Protection Projects

Coastal shoreline protection and beach nourishment are significant issues for coastal states along the Atlantic and Gulf coasts. In some areas, there is a critical need to identify suitable sources of sand for possible use in public works projects for coastal protection. The continental shelf contains large resources of sand and gravel that could be used to support such projects. The U.S. Department of the Interior's (DOI) Minerals Management Service (MMS) provides policy direction and guidance for development of the resources located on the federal portion of the continental shelf. This article highlights the MMS's Sand Program, focusing on its cooperative resource and environmental studies with several coastal states, significant milestones and accomplishments, and anticipated activities in 1998 and beyond. Management of sand resources on the federal portion of the continental shelf has been made easier by a federal state partnership concept. Using this cooperative concept, joint projects are being conducted to investigate offshore sand resources, potential sites, extraction methods, and related environmental conditions. The MMS has procedures for negotiating sand agreements under the Outer Continental Shelf Lands Act (OCSLA) and ensuring that the resources are developed in an environ mentally sound manner. The authority to negotiate with project sponsors, an important recent change in the OCSLA, also resides with the MMS. This 1992 change in OCSLA facilitates the use of Outer Continental Shelf (OCS)resources for public projects. Further, the MMS is authorized to assess a fee based on the value of the resource and the public interest served. The MMS has worked with local sponsors and authorized the use of OCS sand for two projects. However, additional resource and environmental projects, as well as negotiated agreements, are anticipated within the near future with states and local governments along the Atlantic and Gulf coasts.