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USGS2013

Epifluorescent direct counts of bacteria and viruses from topsoil of various desert dust storm regions

Topsoil from arid regions is the main source of dust clouds that move through the earth's atmosphere, and microbial communities within these soils can survive long-range dispersion. Microbial abundance and chemical composition were analyzed in topsoil from various desert regions. Statistical analyses showed that microbial direct counts were strongly positively correlated with calcium concentrations and negatively correlated with silicon concentrations. While variance between deserts was expected, it was interesting to note differences between sample sites within a given desert region, illustrating the 'patchy' nature of microbial communities in desert environments.

Research in Microbiology↗

USGS2002

Chemical attributes of some clouds amid a forest ecosystem's trees

Simultaneous physical and chemical characteristics of clouds amid and above the trees of a montane forest, located about 3.3 km southwest of Mt. Mitchell, NC, were collected between 13 and 22 June 1993. This paper summarizes the chemical characteristics of the cloud droplets amid the trees. The ionic composition and pH of the analyzed amid-canopy cloud water samples are generally consistent with those of previous above-canopy cloud water samples obtained at this site. Magnesium, sodium, and calcium are highly correlated to each other amid the canopy as compared to above the canopy. Above-canopy and amid-canopy cloud-only episodes, with concurrent event-averaged cloud water pH values at or below 3.1, generally contain more magnesium, sodium, and calcium in the amid-canopy cloud water samples compared to concurrent above-canopy cloud water samples. The observed chemical differences between the amid-canopy cloud and the above-canopy cloud suggest an unhealthier environment for the tree canopy when the cloud water traversing this site has a pH value at or below 3.1. The predominant ion deposition fluxes were calculated to provide preliminary data for studies designed to explicitly quantify how the chemical composition of cloud water affects tree health.

Atmospheric Research↗

USGS1991

Seasonal variations of carbon dioxide concentrations in stony, coarse-textured desert soils of southern Nevada, USA

Knowledge of carbon dioxide concentration in desert soils is required in theoretical models of the development of pedogenic and ground-water calcium carbonate. Most studies have concentrated on medium- to fine-textured soils in temperate to humid environments. Very little data exist for CO 2 concentrations in stony, coarse-textured deposits such as those making up alluvial fans and fluvial terraces. The purpose of this study was to obtain CO 2 concentration data in stony, coarse-textured, uncultivated soils in a desert environment. Soil gas samples were collected from two sites—Yucca Wash and Rock Valley—at the Nevada Test Site in southern Nevada between June 1985 and June 1986 to determine soil CO 2 concentrations and their seasonal and depth variations in the soil profile. Soil CO 2 concentrations ranged from 0.03 volume percent in winter and summer to 0.25 volume percent in spring. During the summer, fall, and winter, CO 2 concentrations were close to atmospheric levels and varied randomly with depth. In spring, CO 2 varied with root density, highest concentrations occurring between 40 and 80 cm of depth. Maximum CO 2 values decrease and occur at progressively deeper levels toward the end of spring. Biological activity appears to be limited throughout the year because of the arid climate. During the winter and spring, soil CO 2 appears to be more dependent on temperature than moisture, whereas in the summer and fall it appears to be dependent on moisture. Soil gas samples were also collected during the spring from three sites in the Kyle Canyon area in southern Nevada to determine the variation of soil CO 2 levels with changes in elevation and vegetation. Soil CO 2 values increased from 0.04 to 0.24 volume percent with increasing elevation.

Nevada↗

USGS2008

Sidescan-sonar imagery and surficial geologic interpretations of the sea floor in central Rhode Island Sound

The U.S. Geological Survey (USGS) has been working with the National Oceanic and Atmospheric Administration (NOAA) to interpret the surficial geology of areas along the northeastern coast of the United States. During 2004, the NOAA Ship RUDE conducted Hydrographic Survey H11321 in Rhode Island Sound. This sidescan-sonar and bathymetry survey covers an area of 93 km? located 12 km southeast of Brenton Point, RI in water depths of 28-39 m (fig. 1). The purpose of this report is to delineate sea floor features and sedimentary environments of this area in central Rhode Island Sound using sidescan-sonar and bathymetric data from NOAA Survey H11321 and seismic-reflection data from a previous USGS field study (Needell and others, 1983a). This is important for the study of benthic habitats and provides a framework for future research. Prior work in this area includes the mapping of surface sediments and surficial geology. McMaster (1960) collected sediment samples from Rhode Island Sound and Narragansett Bay and mapped our study area as having a sandy sea floor. In addition, one sample of sand from the National Ocean Service (NOS) Hydrographic Database came from a location in the northeast part of our study area in 1939 (fig. 2; Poppe and others, 2003). McMaster and others (1968) used seismic-reflection profiles to map the locations of a cuesta of Cretaceous sediments crossing Rhode Island Sound and post-Cretaceous drainage channels. Knebel and others (1982) identified sedimentary environments in Rhode Island Sound using sidescan sonographs. Needell and others (1983b) studied the Quaternary geology and mapped the structure, sedimentary environments, and geologic hazards in Rhode Island Sound using sidescan-sonar and seismic-reflection data. Sidescan-sonar and bathymetric data from NOAA Survey H11320, which overlaps the far eastern edge of our study area, was interpreted to consist of basins surrounded by a moraine and bathymetric highs composed of till with areas of rocks, sand waves, hummocks, glaciolacustrine erosional outliers, small scarps and elongate hills (fig. 1; McMullen and others, 2007). Some of those features extend into this study area.

Rhode Island↗

USGS2019

Methane and nitrous oxide temporal and spatial variability in two midwestern USA streams containing high nitrate concentrations

Concentrations and emissions of greenhouse gases CO 2 , CH 4 , and N 2 O commonly are examined individually in aquatic environments in which each is expected to be relatively important; however, their co-occurrence and dynamic interactions in fluvial settings could provide important information about their controlling biogeochemical processes and potential contributions to global climate change. Spatial and temporal variability of CH 4 , N 2 O, and CO 2 concentrations were measured from June 1999 to September 2003 in two nitrate-rich (40–1200 μM) streams draining agricultural land in the midwestern USA that differed ~13-fold in flow. Seasonal (biweekly), diel (hourly), and transport-oriented (reach-scale) sampling approaches were compared. Dissolved gas concentrations exceeded atmospheric equilibrium values up to 700- and 16-fold, for CH 4 and N 2 O, respectively. Mean concentrations were higher in the larger stream than in the smaller stream. In both streams, CH 4 emissions were generally higher in summer-fall and negatively correlated with flow and NO 3 − concentration while N 2 O emissions were generally higher in winter/spring and positively correlated with flow and NO 3 − . In the small stream, diel variations in the concentrations, emissions, and isotopic compositions of CH 4 , N 2 O, and NO 2 − resulted from diel variations in sources, sinks, and air-water gas exchange velocities. Seasonal mean total (CH 4 + N 2 O) area-normalized emission rates, expressed as CO 2 warming potential equivalents, were similar for the two streams, but the total reach-scale emission rate for the larger stream, including CO 2 , was about 2.9 times that of the smaller stream (131.6 vs 46.0 kg CO 2 equivalents km −1 day −1 , respectively). The CH 4 contribution to this flux was 9–28%, despite the relatively high NO 3 − and O 2 concentrations in the streams, indicating contributions from upwelling groundwater or reactions in streambed sediment.

Illinois, Indiana↗

USGS1987

EFFECT OF AN ACID RAIN ENVIRONMENT ON LIMESTONE SURFACES.

Salem limestone samples were exposed to weathering for 1 y in several urban and one rural environments. Samples exposed in the rural location were chemically indistinguishable from the freshly quarried limestone, whereas all samples collected from urban exposure sites developed gypsum stains on the ground-facing surfaces where the stones were not washed by precipitation. The gas-solid reaction of SO//2 with calcite was selected for detailed consideration. It appears from the model that under arid conditions, the quantity of stain deposited on an unwashed surface is independent of atmospheric SO//2 concentration once the surface has been saturated with gypsum. Under wet conditions, surface sulfation and weight loss are probably dominated by mechanisms involving wet stone. However, if the rain events are frequent and delimited by periods of dryness, the quantity of gypsum produced by a gas-solid reaction mechanism should correlate with both the frequency of rain events and the atmospheric SO//2 level.

Materials Performance↗

USGS2011

Microbial survival in the stratosphere and implications for global dispersal

Spores of Bacillus subtilis were exposed to a series of stratosphere simulations. In total, five distinct treatments measured the effect of reduced pressure, low temperature, high desiccation, and intense ultraviolet (UV) irradiation on stratosphereisolated and ground-isolated B. subtilis strains. Environmental conditions were based on springtime data from a mid-latitude region of the lower stratosphere (20 km). Experimentally, each treatment consisted of the following independent or combined conditions: -70 °C, 56 mb, 10-12%relative humidity and 0.00421, 5.11, and 54.64 W/m 2 of UVC (200-280 nm), UVB (280-315 nm), UVA (315-400 nm), respectively. Bacteria were deposited on metal coupon surfaces in monolayers of ~1 x 10 6 spores and prepared with palagonite (particle size< 20 μm). After 6 h of exposure to the stratosphere environment, 99.9% of B. subtilis spores were killed due to UV irradiation. In contrast, temperature, desiccation, and pressure simulations without UV had no effect on spore viability up through 96 h. There were no differences in survival between the stratosphere-isolated versus ground-isolated B. subtilis strains. Inactivation of most bacteria in our simulation indicates that the stratosphere can be a critical barrier to long-distance microbial dispersal and that survival in the upper atmosphere may be constrained by UV irradiation.

Aerobiologia↗

USGS1958

The solusphere - its inferences and study

Water is a fundamental geologic agent active in rock decomposition, erosion, and synthesis. Solutes in water are of particular interest to geochemists as sources of raw material for synthesis or as products of decomposition. When geochemical studies move from the laboratory into natural environment many variables relating to solute hydrology must be considered. As a focal point there has been designed a graphical representation of solute hydrology, the solusphere, which embodies the concepts of land-water occurrence and movement on which are superimposed geologic, biologic, physical, chemical, and cultural processes affecting solutes. The solusphere is demonstrated by passing an imaginary plane through the centre of the earth. This plane intercepts concentric zones designated as rock flowage, saturation, aeration, surface activity, and atmosphere. Transport processes carry solutes within and between zones without alteration or conversion. However, whether stationary or in motion, the water's solute character is constantly subject to (1) alteration processes that change concentration by addition or subtraction of solutes or solvent without loss of solute identities, and (2) conversion processes that change the chemical state and form of solutes. The geochemist is concerned with specific conversion processes, but he also must consider transport, alteration, and other conversion processes that are continually modifying the materials with which he is dealing in nature. The solusphere is an attempt to organize processes affecting the chemical quality of land waters into a unified field of science much like the field of marine chemistry.

Geochimica et Cosmochimica Acta↗

USGS2012

State of the Earth’s cryosphere at the beginning of the 21st century: Glaciers, global snow cover, floating ice, and permafrost and periglacial environments

This chapter is the tenth in a series of 11 book-length chapters, collectively referred to as “this volume,” in the series U.S. Geological Survey Professional Paper 1386, Satellite Image Atlas of Glaciers of the World. In the other 10 chapters, each of which concerns a specific glacierized region of Earth, the authors used remotely sensed images, primarily from the Landsat 1, 2, and 3 series of spacecraft, in order to analyze that glacierized region and to monitor changes in its glaciers. Landsat images, acquired primarily during the period 1972 through 1981, were used by an international team of glaciologists and other scientists to study the various glacierized regions and (or) to discuss related glaciological topics. In each glacierized region, the present distribution of glaciers within its geographic area is compared, wherever possible, with historical information about their past areal extent. The atlas provides an accurate regional inventory of the areal extent of glacier ice on our planet during the 1970s as part of an expanding international scientific effort to measure global environmental change on the Earth’s surface. However, this chapter differs from the other 10 in its discussion of observed changes in all four elements of the Earth’s cryosphere (glaciers, snow cover, floating ice, and permafrost) in the context of documented changes in all components of the Earth System. Human impact on the planet at the beginning of the 21st century is pervasive. The focus of Chapter A is on changes in the cryosphere and the importance of long-term monitoring by a variety of sensors carried on Earth-orbiting satellites or by a ground-based network of observatories in the case of permafrost. The chapter consists of five parts. The first part provides an introduction to the Earth System, including the interrelationships of the geosphere (cryosphere, hydrosphere, lithosphere, and atmosphere), the biosphere, climate processes, biogeochemical cycles, and the critically important hydrologic cycle, in which glacier ice is the second largest reservoir of water after the oceans. The second part assesses the state of glaciers in all of the glacierized regions of the planet, primarily as drawn in the other 10 chapters. It includes sections on ice cores and the climate record they contain, volumetric changes in glaciers, harnessing spaceborne sensors to measure changes in glaciers, and related topics. The third part summarizes trends in global snow cover. The fourth part summarizes long-term changes in area and thickness of floating ice, including polar sea ice and freshwater (lake and river) ice. The fifth part assesses the loss of permafrost and changes in periglacial environments at high latitudes and high altitudes.

Professional Paper↗

USGS1987

Volatilization, transport and sublimation of metallic and non-metallic elements in high temperature gases at Merapi Volcano, Indonesia

Condensates, silica tube sublimates and incrustations were sampled from 500–800°C fumaroles and lava samples were collected at Merapi Volcano, Indonesia in Jan.–Feb., 1984. With respect to the magma, Merapi gases are enriched by factors greater than 10 5 in Se, Re, Bi and Cd; 10 4 –10 5 in Au, Br, In, Pb and W; 10 3 –10 4 in Mo, Cl, Cs, S, Sn and Ag; 10 2 –10 3 in As, Zn, F and Rb; and 1–10 2 in Cu, K, Na, Sb, Ni, Ga, V, Fe, Mn and Li. The fumaroles are transporting more than 10 6 grams/day ( g d "> gd ) of S, Cl and F; 10 4 –10 6 g/d of Al, Br, Zn, Fe, K and Mg; 10 3 –10 4 g d "> gd of Pb, As, Mo, Mn, V, W and Sr; and less than 10 3 g d "> gd of Ni, Cu, Cr, Ga, Sb, Bi, Cd, Li, Co and U. With decreasing temperature (800-500°C) there were five sublimate zones found in silica tubes: 1) cristobalite and magnetite (first deposition of Si, Fe and Al); 2) K-Ca sulfate, acmite, halite, sylvite and pyrite (maximum deposition of Cl, Na, K, Si, S, Fe, Mo, Br, Al, Rb, Cs, Mn, W, P, Ca, Re, Ag, Au and Co); 3) aphthitalite (K-Na sulfate), sphalerite, galena and Cs-K. sulfate (maximum deposition of Zn, Bi, Cd, Se and In; higher deposition of Pb and Sn); 4) Pb-K chloride and Na-K-Fe sulfate (maximum deposition of Pb, Sn and Cu); and 5) Zn, Cu and K-Pb sulfates (maximum deposition of Pb, Sn, Ti, As and Sb). The incrustations surrounding the fumaroles are also chemically zoned. Bi, Cd, Pb, W, Mo, Zn, Cu, K, Na, V, Fe and Mn are concentrated most in or very close to the vent as expected with cooling, atmospheric contamination and dispersion. The highly volatile elements Br, Cl, As and Sb are transported primarily away from high temperature vents. Ba, Si, P, Al, Ca and Cr are derived from wall rock reactions. Incomplete degassing of shallow magma at 915°C is the origin of most of the elements in the Merapi volcanic gas, although it is partly contaminated by particles or wall rock reactions. The metals are transported predominantly as chloride species. As the gas cools in the fumarolic environment, it becomes saturated with sublimate phases that fractionate from the gas in the order of their equilibrium saturation temperatures. Devolatilization of a cooling batholith could transport enough acids and metals to a hydrothermal system to play a significant role in forming an ore deposit. However, sublimation from a high temperature, high velocity carrier gas is not efficient enough to form a large ore deposit. Re, Se, Cd and Bi could be used as supporting evidence for magmatic fluid transport in an ore deposit.

Geochimica et Cosmochimica Acta↗

USGS2013

Archive of U.S. Geological Survey selected single-beam bathymetry datasets, 1969-2000

New national programs, as well as natural and man-made disasters, have raised awareness about the need to find new and improved ways to share information about the coastal and marine environment with a wide-ranging public audience. The U.S. Geological Survey (USGS) Coastal and Marine Geology Program (CMGP) has begun a large-scale effort to incorporate the program's published, digital geophysical data into a single point of access known as the Coastal and Marine Geoscience Data System (CMGDS) (http://cmgds.marine.usgs.gov/). To aid in data discovery, work is also being done to import CMGP data into highly visible data and information resources, such as the National Oceanic and Atmospheric Administration's (NOAA) National Geophysical Data Center (NGDC) and two widely used Earth-science tools, GeoMapApp (GMA) (http://www.geomapapp.org) and Virtual Ocean (VO) (http://www.virtualocean.org/). This task of the CMGP Integrated Data Management System project will help support information exchange with partners, regional planning groups, and the public, as well as facilitate integrated spatial-data analysis. Sharing USGS-CMGP geophysical data via CMGDS, NGDC, GMA, and VO will aid data discovery and enable the data to support new purposes beyond those for which the data were originally intended. In order to make data available to NGDC, and from there into GMA and VO, the data must be reformatted into a standard exchange format and published. In 1977, a group of geophysical data managers from the public and private sectors developed the MGD77 format as the standard exchange format for geophysical data. In 2010, a tab-delimited version of the format was added as MGD77T (Hittelman and others, 1977). The MGD77T geophysical data format can include bathymetry, magnetics, gravity, and seismic navigation data. It is used for the transmission of data between marine institutions, data centers, and can be used by various software programs as an exchange format. A header (documentation) file and data file are created for each survey (Hittelman and others, 1977). More details about the MGD77T format are available at http://www.ngdc.noaa.gov/mgg/dat/geodas/docs/mgd77.pdf (74MB PDF). This archive describes the detailed steps used to convert single-beam bathymetry and navigation files into the MGD77T format (Hittelman and others, 1977) for submission to NGDC and formal Federal Geographic Data Committee (FGDC) (http://www.fgdc.gov/metadata) metadata as a publication of these single-beam bathymetry datasets.

Data Series↗

USGS2010

Surficial geology of the sea floor in Long Island Sound offshore of Plum Island, New York

The U.S. Geological Survey (USGS), the Connecticut Department of Environmental Protection, and the National Oceanic and Atmospheric Administration (NOAA) have been working cooperatively to interpret surficial sea-floor geology along the coast of the Northeastern United States. NOAA survey H11445 in eastern Long Island Sound, offshore of Plum Island, New York, covers an area of about 12 square kilometers. Multibeam bathymetry and sidescan-sonar imagery from the survey, as well as sediment and photographic data from 13 stations occupied during a USGS verification cruise are used to delineate sea-floor features and characterize the environment. Bathymetry gradually deepens offshore to over 100 meters in a depression in the northwest part of the study area and reaches 60 meters in Plum Gut, a channel between Plum Island and Orient Point. Sand waves are present on a shoal north of Plum Island and in several smaller areas around the basin. Sand-wave asymmetry indicates that counter-clockwise net sediment transport maintains the shoal. Sand is prevalent where there is low backscatter in the sidescan-sonar imagery. Gravel and boulder areas are submerged lag deposits produced from the Harbor Hill-Orient Point-Fishers Island moraine segment and are found adjacent to the shorelines and just north of Plum Island, where high backscatter is present in the sidescan-sonar imagery.

Open-File Report↗

USGS2010

Sea-floor geology and character offshore of Rocky Point, New York

Open-File Report↗

USGS2021

Warming induces divergent stomatal dynamics in co-occurring boreal trees

Climate warming will alter photosynthesis and respiration not only via direct temperature effects on leaf biochemistry but also by increasing atmospheric dryness, thereby reducing stomatal conductance and suppressing photosynthesis. Our knowledge on how climate warming affects these processes is mainly derived from seedlings grown under highly controlled conditions. However, little is known regarding temperature responses of trees growing under field settings. We exposed mature tamarack and black spruce trees growing in a peatland ecosystem to whole-ecosystem warming of up to +9°C above ambient air temperatures in an ongoing long-term experiment (SPRUCE: Spruce and Peatland Responses Under Changing Environments). Here, we report the responses of leaf gas exchange after the first two years of warming. We show that the two species exhibit divergent stomatal responses to warming and vapor pressure deficit. Warming of up to 9°C increased leaf N in both spruce and tamarack. However, higher leaf N in the warmer plots translate into higher photosynthesis in tamarack but not in spruce, with photosynthesis being more constrained by stomatal limitations in spruce than in tamarack under warm conditions. Surprisingly, dark respiration did not acclimate to warming in spruce, and thermal acclimation of respiration was only seen in tamarack once changes in leaf N were considered. Our results highlight how warming can lead to differing stomatal responses to warming in co-occurring species, with consequent effects on both vegetation carbon and water dynamics.

Global Change Biology↗

USGS1956

The physical behavior and geologic control of radon in mountain streams

Radon measurement were made in several small, turbulent mountain streams in the Wasatch Mountains near Salt Lake City and Ogden, Utah, to determine the relationship between the distribution of radon and its geologic environment. In this area, the distribution of radon in streams can be sued to locate points where relatively large amounts of radon-bearing ground water enter the stream, although other evidence of spring activity may be lacking. These points of influence ground water are marked by abrupt increases (as much as two orders of magnitude within a distance of 50 feet) in the radon content of the stream waters. The excess radon in the stream water is then rapidly lost to the atmosphere through stream turbulence. The rate of radon dissipation is an exponential function, of different slopes, with respect to distance of streamflow, and depend upon the rate and volume of streamflow, and the gradient and nature of the stream channel. The higher radon concentration can be generally related to specific stratigraphic horizons in several different drainage area. Thus, lithologic units which act as the primary aquifers can be identifies. In one area, thrust faults were found to control he influx of ground water into the stream. Estimates, based on radon concentration in stream and related spring waters, can also be made of the major increments of addition of ground water to streamflow where conventional methods such as stream gaging are not practical. The radon in the waters studied was found to be almost completely unsupported by radium in solution.

Utah↗

USGS2023

Advancing best practices for the analysis of the vulnerability of military installations in the Pacific Basin to coastal flooding under a changing climate – RC-2644

Coastal flooding takes many forms, ranging from major flooding associated with storms to minor flooding associated with exceptionally high tides and other oceanic and atmospheric phenomena on storm-free days. A major societal challenge is to understand and predict how flood magnitude and frequency will manifest at particular places and times, now and in the future. Of particular interest here is how coastal flooding will impact Department of Defense (DoD) installations. In response to this need, this work aims to advance the practical application of statistical and other analytical techniques that can be used to assess the exposure, and ultimately the vulnerability, of built and natural environments to the impacts of coastal flooding. A variety of methods are described and applied to assess exposure. This includes tide gauge station-based diagnosis and prognosis of patterns and trends of Still Water Level, techniques to characterize the expression of ‘lesser extremes’ (e.g., sub-annual to subdecadal event probabilities), and region-wide analysis that improves upon results obtained from conventional single-tide gauge analyses. A novel hybrid statistical and dynamical modeling approach is applied to the analysis of Total Water Levels, necessary for exposure assessment along shorelines exposed to wave action. The hybrid exposure assessment modeling approach is incorporated into a broader mission-based protocol for the assessment of resilience to coastal flooding at the installation level. Demonstrated via an exemplar assessment, which takes into account functional (lost day) as well as financial impacts (lost dollars), the protocol meets the demand for an actionable characterization of how DoD installations will be affected by coastal flooding and improves DoD’s ability to make informed decisions about how to adapt to its effects. The methods described, evaluated, and applied here, including innovative approaches and proof-of-concept products developed through this work, are incorporated into and considered within an analytical framework that serves as guidance as to their relative merits with respect to coastal flood exposure assessment in various circumstances and settings, and illustrates best practices. This will provide engineers, scientists and other practitioners with an enhanced capability to generate information that can be used to support area-wide assessment related to climate adaptation planning and disaster risk reduction as well as site-specific analysis related to design and maintenance of facilities and infrastructure. While the focus is on a select set of DoD sites in the Pacific Basin, the results have broad applicability nationally as well as globally.

Final Report↗

USGS2022

Bathymetry retrieval from CubeSat image sequences with short time lags

The rapid expansion of CubeSat constellations could revolutionize the way inland and nearshore coastal waters are monitored from space. This potential stems from the ability of CubeSats to provide daily imagery with global coverage at meter-scale spatial resolution. In this study, we explore the unique opportunity to improve the retrieval of bathymetry offered by CubeSats, specifically those of the PlanetScope constellation. The orbital design of the PlanetScope constellation enables the acquisition of image sequences with short time lags (from seconds to hours). This characteristic allows multiple images to be captured during a short period of steady bathymetric conditions, especially in dynamic environments like rivers. We hypothesize that taking the ensemble mean of a CubeSat image sequence can enhance bathymetry retrieval compared to standard single-image analysis. Along with the existing optimal band ratio analysis (OBRA) algorithm, we also use a new neural network-based depth retrieval (NNDR) technique to infer bathymetry from both individual and time-averaged images. The two methodologies are evaluated using field data from five different river reaches with depths up to 15 m and both top-of-atmosphere (TOA) radiance and bottom-of-atmosphere (BOA) surface reflectance PlanetScope data products. Despite low spectral resolution and concerns about the radiometric quality of CubeSat imagery, accuracy assessment based on in-situ comparisons indicates the potential (0.52 < R 2 < 0.7 for the NNDR method) of PlanetScope imagery to retrieve depths up to ∼ 10 m in clear water conditions. The proposed image averaging consistently improves bathymetry retrieval over single image analysis. The NNDR technique was found to outperform OBRA, illustrating the importance of leveraging all spectral bands through machine learning approaches. TOA data provided more robust bathymetry results than BOA data for the OBRA technique, but the NNDR technique was minimally impacted by the type of data product.

International Journal of Applied Earth Observation↗

USGS2013

Organic wastewater compounds in water and sediment in and near restored wetlands, Great Marsh, Indiana Dunes National Lakeshore, 2009–11

A cooperative investigation between the U.S. Geological Survey and the National Park Service was completed from 2009 through 2011 to understand the occurrence, distribution, and environmental processes affecting concentrations of organic wastewater compounds in water and sediment in and near Great Marsh at the Indiana Dunes National Lakeshore in Beverly Shores, Indiana. Sampling sites were selected to represent hydrologic inputs to the restored wetlands from adjacent upstream residential and less developed areas and to represent discharge points of cascading cells within the restored wetland. A multiphase approach was used for the investigation. Discrete water samples and time-integrated passive samples were analyzed for 69 organic wastewater compounds. Continuous water-level information and periodic streamflow measurements characterized flow conditions at discharge points from restored wetland cells. Wetland sediments were collected and analyzed for sorptive losses of organic wastewater compounds and to evaluate of the potential for wetland sediments to biotransform organic wastewater compounds. A total of 52 organic wastewater compounds were detected in discrete water samples at 1 or more sites. Detections of organic wastewater compounds were widespread, but concentrations were generally low and 95 percent were less than 2.1 micrograms per liter. Six compounds were detected at concentrations greater than 2.1 micrograms per liter—four fecal sterols (beta-sitosterol, cholesterol, beta-stigmastanol, and 2-beta coprostanol), one plasticizer (bis-2-ethylhex ylphthalate), and a non-ionic detergent (4-nonylphenol diethoxylate). Two 1-month deployments of time-integrative passive samplers, called polar organic chemical integrative samplers, detected organic wastewater compounds at lower concentrations than were possible with discrete water samples. Isopropyl benzene (solvent), caffeine (plant alkaloid, stimulant), and hexahydrohexamethyl cyclopentabenzopyran (fragrance) were detected in more than half of the extracts from passive samplers, but they were not detected in any discrete water sample. The Yeast Estrogen Screen assay identified measurable estrogenicity in one passive sampler extract from the most downstream wetland site in both the April and November–December 2011 deployments and in passive sampler extracts from one residential and one upstream site in the November–December 2011 deployment only. Surface-water levels in the restored wetland cells were monitored continuously using submersible pressure transducers in hand-driven well points screened in the surface water. Surface-water levels in the wetland cells responded quickly to precipitation and substantially receded within 2 days following the largest rainfall events. Seasonal patterns in water levels generally showed higher and more variable surface-water levels in the wetland cells during spring and early summer. Water levels in the wetland cells fell below the elevation of the control structures and ceased to flow over the spillways during extended dry periods (primarily late summer and early fall). Daily loads of seven organic wastewater compounds, as indicators of septic system effluent, were estimated for samples collected at wetland outlet spillways when flow measurements could be made. Median daily loads of the indicator organic wastewater compounds increased in downstream order, and the largest median loads were measured at the most downstream site. Median daily loads were higher for samples collected in spring and summer than those collected in fall, as the higher seasonal water levels increased streamflow at the wetland outlet spillways. Wetland sediment samples were analyzed for 84 organic wastewater compounds, polycyclic aromatic hydrocarbons, and semivolatile organic compounds to investigate the fate of contaminants in Great Marsh. The top five detected compounds by total mass in wetland sediment samples were beta-sitosterol, beta-stigmastanol, cholesterol, bis(2-ethylhexyl) phthalate, and phenol. Polycyclic aromatic hydrocarbons also were frequently detected in wetland sediment samples. Source apportionment of polycyclic aromatic hydrocarbon detections indicated atmospheric sources of pyrogenic compounds, rather than residential sources. Comparisons of polycyclic aromatic hydrocarbon concentrations in wetland sediment samples to sediment quality target guidelines indicated the potential for harmful effects on sediment-dwelling organisms at several sites. Biodegradation of select endocrine-disrupting compounds (17α-ethinylestradiol, 4-nonylphenol, triclocarban, and bisphenol A) in shallow wetland sediments was evaluated in laboratory experiments by using carbon-14 radiolabeled model contaminants. Substantial biodegradation of certain organic wastewater compounds were demonstrated, primarily in oxic (oxygen containing) environments. One of four modeled compounds, bisphenol A, was biodegraded in anoxic (oxygen free) environments. Only sediments collected nearest residential areas exhibited degradation of the synthetic birth control pharmaceutical, 17α-ethinylestradiol, possibly owing to adaptation and acclimation of the indigenous microbial community to septic discharge and the resultant selection of a microbial capability for biodegradation of 17α-ethinylestradiol.

Indiana↗