A5013328651- Climate change and permafrost
- Cryospheric studies and observations
- Seismic Waves and Analysis
- Methane Hydrates and Related Phenomena
- Microbial Community Ecology and Physiology
- Seismology and Earthquake Studies
- Seismic Imaging and Inversion Techniques
- Geophysical Methods and Applications
- Geology and Paleoclimatology Research
- Hydrocarbon exploration and reservoir analysis
- Smart Materials for Construction
- Geophysical and Geoelectrical Methods
- Geological Studies and Exploration
- Polar Research and Ecology
- Marine Biology and Environmental Chemistry
- Geophysics and Gravity Measurements
- Genomics and Phylogenetic Studies
- Marine and coastal ecosystems
- Arctic and Antarctic ice dynamics
- Underwater Acoustics Research
- Marine Ecology and Invasive Species
- Soil Moisture and Remote Sensing
- Marine Biology and Ecology Research
- earthquake and tectonic studies
- Botany and Geology in Latin America and Caribbean
United States Geological Survey
2019-2024
Geology, Geophysics, and Geochemistry Science Center
2020-2024
University of Florida
1990-2019
Sandia National Laboratories
2017
UNSW Sydney
1996-2006
Australian Defence Force Academy
2004
Australian Antarctic Division
1990-1994
University of Tasmania
1990-1994
Abstract Our understanding of subsurface processes suffers from a profound observation bias: seismometers are sparse and clustered on continents. A new seismic recording approach, distributed acoustic sensing (DAS), transforms telecommunication fiber‐optic cables into sensor arrays enabling meter‐scale over tens kilometers linear fiber length. We analyze cataloged earthquake observations three DAS with different horizontal geometries to demonstrate some possibilities using this technology....
A dark-green-pigmented marine bacterium, previously designated D2, which produces components that are inhibitory to common fouling organisms has been characterized and assessed for taxonomic assignment. Based on direct double-stranded sequencing of the 16S rRNA gene, D2T was found show highest similarity (93%) members genus Pseudoalteromonas. The G+C content is 42 mol%, it a facultatively anaerobic rod oxidase-positive. motile by sheathed polar flagellum, exhibited non-fermentative...
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout JournalEditorsTheme Sections 244:1-15 (2002) - doi:10.3354/meps244001 Algicidal bacteria associated with blooms of a toxic dinoflagellate in temperate Australian estuary J. H. Skerratt1,2,*, P. Bowman1,2,3, G. Hallegraeff4, S. James5, D. Nichols1,2,6 1Antarctic Cooperative Research Center, 2Institute Antarctic and Southern Ocean Studies...
Abstract Widespread permafrost thaw in response to changing climate conditions has the potential dramatically impact ecosystems, infrastructure, and global carbon budget. Ambient seismic noise techniques allow passive subsurface monitoring that could provide new insights into vulnerability active‐layer processes. Using nearly 2 years of continuous data recorded near Fairbanks, Alaska, we measured relative velocity variations showed a clear seasonal cycle reflecting freeze thaw. Relative...
Abstract The Mississippi Alluvial Plain hosts one of the most prolific shallow aquifer systems in United States but is experiencing chronic groundwater decline. Reelfoot rift and New Madrid seismic zone underlie region represent an important poorly understood hazard. Despite its societal economic importance, subsurface architecture has not been mapped with spatial resolution needed for effective management. Here, we present airborne electromagnetic, magnetic, radiometric observations,...
Abstract Methane (CH 4 ) emissions from climate‐sensitive ecosystems within the northern permafrost region represent a potentially large but highly uncertain source, with current estimates spanning factor of seven (11–75 Tg CH yr −1 ). Accelerating thaw threatens significant increases in pan‐Arctic emissions, amplifying carbon feedback. We used airborne imaging spectroscopy meter‐scale spatial resolution and broad coverage to identify previously undiscovered emission hotspot adjacent...
Abstract Permafrost degradation is rapidly increasing in response to a warming Arctic climate, altering landscapes and damaging critical infrastructure. Solutions for monitoring permafrost thaw dynamics are essential understand biogeochemical feedbacks as well issue warnings hazardous geotechnical conditions. We investigate the feasibility of using permanently installed fiber‐optic seismic networks. conducted 2‐month campaign during controlled experiment permanent surface orbital vibrator...
Abstract Borehole nuclear magnetic resonance (bNMR) data are typically used to infer in situ hydrologic properties. Partial water content as a function of pore size is estimated by fitting the measured NMR response multi‐exponential T 2 distribution, and sum amplitudes equals total volumetric content. From these parameters, several empirical relationships commonly hydraulic conductivity from NMR‐estimated distribution. Often, parameters through deterministic inversion methods that produce...
Two questions of relevance to the establishment marine biofouling communities were addressed, viz (1) what is frequency with which bacterial strains isolated from living and inanimate surfaces in environment show inhibitory activity against settlement common fouling organisms, (2) antifouling bacterium, D2, an inhabitant different waters, how unique this its mode action target organisms? With respect first question, ninety three bacteria various rock tested larvae Balanus amphitrite spores...
Abstract Cross correlations of seismic noise can potentially record large changes in subsurface velocity due to permafrost dynamics and be valuable for long‐term Arctic monitoring. We applied interferometry, using moving window cross‐spectral analysis (MWCS), 2 years ambient data recorded central Alaska investigate whether could used quantify relative seasonal active‐layer dynamics. The (>75%) between frozen thawed soil caused prevalent cycle‐skipping which made the method unusable this...
Abstract Thermokarst lakes accelerate deep permafrost thaw and the mobilization of previously frozen soil organic carbon. This leads to microbial decomposition large releases carbon dioxide (CO 2 ) methane (CH 4 that enhance climate warming. However, time scale permafrost-carbon emissions following is not well known but important for understanding how abrupt impacts feedback. We combined field measurements radiocarbon dating CH ebullition with (a) an assessment lake area changes delineated...
ABSTRACT The marine epiphytic bacterium Pseudoalteromonas tunicata produces a range of extracellular secondary metabolites that inhibit an array common fouling organisms, including fungi. In this study, we test the hypothesis ability to fungi provides P. with advantage during colonization surface. Studies on transposon-generated antifungal-deficient mutant , FM3, indicated long-chain fatty acid-coenzyme A ligase is involved in production broad-range antifungal compound by . Flow cell...
Abstract Warming temperatures and increasing disturbance by wildfire extreme weather events is driving permafrost change across northern latitudes. The state of varies widely in space time, depending on landscape, climate, hydrologic, ecological factors. Despite its importance, few approaches commonly measure monitor the changes deep (>1 m) conditions with high spatial resolution. Here, we use electrical resistivity tomography surveys along two transects interior Alaska previously...
Abstract Landscape drying associated with permafrost thaw is expected to enhance microbial methane oxidation in arctic soils. Here we show that ice-rich, Yedoma deposits, comprising a disproportionately large fraction of pan-arctic soil carbon, present an alternate trajectory. Field and laboratory observations indicate talik (perennially thawed soils permafrost) development unsaturated uplands leads unexpectedly emissions (35–78 mg m −2 d −1 summer, 150–180 winter). Upland were nearly three...
Indirect immunofluorescence was used to quantify the seasonal variation of four halophilic aerobic Antarctic bacteria in saline lakes from July 1990 January 1991. Antibodies were raised against type strains Australian Collection Microorganisms. During summer, all serogroups identified waters with total dissolved salts above 61%. Maximal abundances Halomonas meridiana, H. subglaciescola and Flavobacterium gondwanense observed at discrete depths within water column two most hypersaline about...
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Abstract The impact of permafrost thaw on hydrologic, thermal, and biotic processes remains uncertain, in part due to limitations subsurface measurement capabilities. To better understand thermokarst environments, we collocated geophysical biogeochemical instruments along a gradient between forested collapse‐scar bogs at the Alaska Peatland Experiment site near Fairbanks, Alaska. Ambient seismic noise monitoring provided continuous high‐temporal resolution measurements water ice saturation...
Fracture systems are important pathways for fluid and solute transport exert a critical influence on the hydraulic properties of aquifers reservoirs. Therefore, detailed knowledge fracture locations, connections, evolution is crucial both groundwater energy applications (e.g., enhanced geothermal, oil gas recovery, carbon sequestration, wastewater injection). The innovative combination distributed acoustic sensing (DAS) ambient seismic noise techniques has potential to detect characterize at...
We investigated a new technique for aquifer characterization that uses cross-correlation of ambient seismic noise to determine velocity structure the Floridan system (FAS). Accurate systems is vital hydrogeological research and groundwater management but difficult due limited subsurface data heterogeneity. Previous on carbonate FAS found confining units high permeability flow zones have distinct velocities. deployed an array 9 short period seismometers from 11/2013 3/2014 in Indian Lake...
Abstract In the Gulf of Alaska region, sediment has rapidly accumulated (>1 km/my) in trench sourced from intensified glaciation past ∼1.2 million years. This rapid accumulation increases overburden and should accelerate dehydration hydrous minerals by insulating underlying column. These processes have potential to generate fluid overpressures low permeability sediments entering subduction zone. A 1‐D model was developed simulate reaction progress investigate excess pore pressures as...