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Robert Anderson

Publications and source records attributed to Robert Anderson.

12 recordsLinked to original sources
USGS2015

Effects of high salinity wastewater discharges on unionid mussels in the Allegheny River, Pennsylvania

We examined the effect of high salinity wastewater (brine) from oil and natural gas drilling on freshwater mussels in the Allegheny River, Pennsylvania, during 2012. Mussel cages (N = 5 per site) were deployed at two sites upstream and four sites downstream of a brine treatment facility on the Allegheny River. Each cage contained 20 juvenile northern riffleshell mussels Epioblasma torulosa rangiana). Continuous specific conductance and temperature data were recorded by water quality probes deployed at each site. To measure the amount of mixing throughout the entire study area, specific conductance surveys were completed two times during low-flow conditions along transects from bank to bank that targeted upstream (reference) reaches, a municipal wastewater treatment plant discharge upstream of the brine-facility discharge, the brine facility, and downstream reaches. Specific conductance data indicated that high specific conductance water from the brine facility (4,000–12,000 µS/cm; mean 7,846) compared to the reference reach (103–188 µS/cm; mean 151) is carried along the left descending bank of the river and that dilution of the discharge via mixing does not occur until 0.5 mi (805 m) downstream. Juvenile northern riffleshell mussel survival was severely impaired within the high specific conductance zone (2 and 34% at and downstream of the brine facility, respectively) and at the municipal wastewater treatment plant (21%) compared to background (84%). We surveyed native mussels (family Unionidae) at 10 transects: 3 upstream, 3 within, and 4 downstream of the high specific conductance zone. Unionid mussel abundance and diversity were lower for all transects within and downstream of the high conductivity zone compared to upstream. The results of this study clearly demonstrate in situ toxicity to juvenile northern riffleshell mussels, a federally endangered species, and to the native unionid mussel assemblage located downstream of a brine discharge to the Allegheny River.

Pennsylvania↗
USGS2008

Surface processes recorded by rocks and soils on Meridiani Planum, Mars: Microscopic Imager observations during Opportunity's first three extended missions

The Microscopic Imager (MI) on the Mars Exploration Rover Opportunity has returned images of Mars with higher resolution than any previous camera system, allowing detailed petrographic and sedimentological studies of the rocks and soils at the Meridiani Planum landing site. Designed to simulate a geologist's hand lens, the MI is mounted on Opportunity's instrument arm and can resolve objects 0.1 mm across or larger. This paper provides an overview of MI operations, data calibration, and analysis of MI data returned during the first 900 sols (Mars days) of the Opportunity landed mission. Analyses of Opportunity MI data have helped to resolve major questions about the origin of observed textures and features. These studies support eolian sediment transport, rather than impact surge processes, as the dominant depositional mechanism for Burns formation strata. MI stereo observations of a rock outcrop near the rim of Erebus Crater support the previous interpretation of similar sedimentary structures in Eagle Crater as being formed by surficial flow of liquid water. Well‐sorted spherules dominate ripple surfaces on the Meridiani plains, and the size of spherules between ripples decreases by about 1 mm from north to south along Opportunity's traverse between Endurance and Erebus craters.

Journal of Geophysical Research E: Planets↗
USGS2006

Overview of the Microscopic Imager Investigation during Spirit's first 450 sols in Gusev crater

The Microscopic Imager (MI) on the Mars Exploration Rover Spirit has returned images of Mars with higher resolution than any previous camera system, allowing detailed petrographic and sedimentological studies of the rocks and soils at the Gusev landing site. Designed to simulate a geologist's hand lens, the MI is mounted on Spirit's instrument arm and can resolve objects 0.1 mm in size or larger. This paper provides an overview of MI operations, data calibration, processing, and analysis of MI data returned during the first 450 sols (Mars days) of the Spirit landed mission. The primary goal of this paper is to facilitate further analyses of MI data by summarizing the methods used to acquire and process the data, the radiometric and geometric accuracy of MI data products, and the availability of archival products. In addition, scientific results of the MI investigation are summarized. MI observations show that poorly sorted soils are common in Gusev crater, although aeolian bedforms have well‐sorted coarse sand grains on their surfaces. Abraded surfaces of plains rocks show igneous textures, light‐toned veins or fracture‐filling minerals, and discrete coatings. The rocks in the Columbia Hills have a wide variety of granular textures, consistent with volcaniclastic or impact origins. Case hardening and submillimeter veins observed in the rocks as well as soil crusts and cemented clods imply episodic subsurface aqueous fluid movement, which has altered multiple geologic units in the Columbia Hills. The MI also monitored Spirit's solar panels and the magnets on the rover's deck.

Journal of Geophysical Research E: Planets↗
USGS1999

Preliminary results on photometric properties of materials at the Sagan Memorial Station, Mars

Reflectance measurements of selected rocks and soils over a wide range of illumination geometries obtained by the Imager for Mars Pathfinder (IMP) camera provide constraints on interpretations of the physical and mineralogical nature of geologic materials at the landing site. The data sets consist of (1) three small “photometric spot” subframed scenes, covering phase angles from 20° to 150°; (2) two image strips composed of three subframed images each, located along the antisunrise and antisunset lines (photometric equator), covering phase angles from ∼0° to 155°; and (3) full‐image scenes of the rock “Yogi,” covering phase angles from 48° to 100°. Phase functions extracted from calibrated data exhibit a dominantly backscattering photometric function, consistent with the results from the Viking lander cameras. However, forward scattering behavior does appear at phase angles >140°, particularly for the darker gray rock surfaces. Preliminary efforts using a Hapke scattering model are useful in comparing surface properties of different rock and soil types but are not well constrained, possibly due to the incomplete phase angle availability, uncertainties related to the photometric function of the calibration targets, and/or the competing effects of diffuse and direct lighting. Preliminary interpretations of the derived Hapke parameters suggest that (1) red rocks can be modeled as a mixture of gray rocks with a coating of bright and dark soil or dust, and (2) gray rocks have macroscopically smoother surfaces composed of microscopically homogeneous, clear materials with little internal scattering, which may imply a glass‐like or varnished surface.

Journal of Geophysical Research E: Planets↗
USGS1910

Geology and oil resources of the Coalinga District, California

The Coalinga oil district occupies a strip of land about 50 miles in length by 15 miles in width along the northeastern base of the Diablo Range, on the southwest side of the San Joaquin Valley, in western Fresno and Kings counties in central California. The region is accessible by rail from the main lines of both the Southern Pacific and the Atchison, Topeka and Santa Fe railroads by a branch line of the Southern Pacific running westerly from Goshen to Coalinga. The proved productive oil territory is comprised in a band 13 miles long by 3 miles wide in the foothills in the northern end of the district, within the Coalinga field proper, together with a narrow strip along the district's southwestern boundary in the Kreyenhagen field.

California↗