SEMINAR - John A. Izbicki

Sources of Fecal Indicator Bacteria in Urban Streams and Ocean Beaches, Santa Barbara, California

John A. Izbicki
United State Geological Survey
Hydrogeologist

Wednesday, November 5th, 2008

Fecal indicator bacteria (FIB) concentrations in urban streams and ocean beaches in Santa Barbara, Calif. can exceed water-quality standards for recreational water. During low flow, high FIB concentrations in urban streams were associated with point discharges from storm drains, and concentrations in urban streamflow varied three-fold over the course of a day as a result of small variations in storm drain discharge. Human-specific Bacteroides was present in some sampled storm drains. FIB concentrations were highest in stormflow runoff, although concentrations decreased as successive storms washed FIB from the urban watershed. Sources of FIB to near-shore ocean water included surface discharges from urban streams, and fecal material from birds associated with kelp and sand along the beachfront. FIB concentrations were higher during the ebb of the “spring” tide and decreased to less than the detection limit during low tide when 222Rn and electromagnetic seepmeter data show ground-water discharge to the ocean was greatest. Ground-water discharge and leakage from sewer lines were not sources of FIB to nearshore ocean water. Interpretations of the sources of FIB from Principal Component Analysis (PCA) of genetic (T-RFLP), molecular (PLFA), and trace-organic (such as caffeine, fecal sterols, and detergent metabolites) data generally agreed with interpretations supported by physical measures of water flow. The most robust PCA results were from PLFA data which explained 97 percent of the total variance within the first and second principal components. Less variance was explained in PCA analysis of T-RFLP and trace-organic data, although these tracers captured relations not apparent in PLFA data. Certain compounds lent themselves to specific interpretations on the origin of FIB. The T-RFLP data indicated an unexpectedly large diversity of microorganisms, including FIB, in shallow ground water where street runoff was discharged to beach sands.

Seismic Micro-Technology awards gift of Kingdom Software

Seismic Micro-Technology awards gift of Kingdom Software valued at $1,192,896.58



The Department of Geological Science has just been awarded three-year grant of the Kingdom Suite seismic interpretation software (10 seat license valued at $1,192,896.58) through the University Gift program. This software is used widely in the petroleum industry and will be a great advantage for our students entering the petroleum industry as well as a valuable tool for research and interpretation of seismic reflection data.

The KINGDOM Software (TKS) enables intuitive, integrated geoscientific workflow spanning:

• Interpretation: Pick horizons and faults, overlay seismic with well data, correlate formation tops, contour surfaces, and view in 2D or 3D.
• Modeling: View 1D synthetic seismograms, create velocity models for time to depth conversions, and convert resistivity and density logs to velocity.
• Analytics: Analyze pre-stack gathers, perform quick look log analysis, generate velocity volumes, conduct attribute analysis and create custom calculators.
• Data Management: Manage multiple projects and migrate data between major interpretation software platforms.

University Program

The goal of SMT's Educational Grant Program is to put workstation software in the classroom so those students graduating from universities are equipped for the job market with workstation experience. The KINGDOM Software is utilized for both teaching and research at academic institutions in 27 countries worldwide.

As of January 1, 2008, SMT has donated thousands of software licenses to 143 colleges and universities around the world. We offer each institute multiple copies of KINGDOM software for their teaching lab and for the professor or instructor's use in classes. Beginning in 2001, three-year grants, including all maintenance support and updates, have been donated with a total estimated value of over one hundred million dollars ($100M).

http://www.seismicmicro.com/

New Member of the Family

Nikolai Waldemar Peterson

Gary and Daria Peterson proudly announce the birth of their firstr child, Nikolai Waldermar Peterson.

Born: Thursday, October 6, 2008 at 4:22am,
9 lbs and 8 oz, 22 inches (15in head circumference).

SEMINAR - Frank Corsetti

Stromatolites: Myths and Legends

Frank Corsetti
Department of Earth Science
University of Southern California

Wednesday, October 29th, 2008

Stromatolites are classically interpreted as “organo-sedimentary structures”, where layers and doming/branching result from microbial mats. As such, they could be considered quintessential ‘astrobiologic’ structures—a stromatolite, as a macroscopic manifestation of microbial processes, would be much easier to image remotely (on Mars, for example) than a microbe. While there is no doubt that some (perhaps most) stromatolites on Earth were formed with biologic influence, recent work has demonstrated that stromatolite-like structures have formed without biologic input. Can we tell the difference? When faced with determining the presence of life elsewhere in our solar system, “extraordinary claims require extraordinary evidence”—do stromatolites pass this test?

SEMINAR - Gregory J. Holk

The Long-Term Hydrologic Cycle: Stable Isotope Clues for Fluid Pathways in Earth's Crust

Gregory J. Holk
Department of Geological Sciences
California State University, Long Beach

Wednesday, October 22nd, 2008

The circulation of aqueous fluids through the Earth’s crust has profound effects on its geologic evolution, the formation of ore deposits, the migration of hydrocarbons from source to sites of accumulation, and the storage of groundwater resources. Major crustal-scale fault zones and crustal heat distribution both play a major role to determine fluid pathways. Case studies that showcase the interplay between crustal thermal evolution and the permeable zones, such as major crustal shear zones, are presented to demonstrate the importance of fluids on the tectonic evolution of the Earth’s crust and the formation of ore deposits. These studies include: (1) the role of water in the magmatic and tectonic evolution of metamorphic core complexes at the Southern Omineca Belt, British Columbia (Holk and Taylor, 2007) and the southern White Pine Range, east-central Nevada, (2) metamorphic fluids and the evolution of the Cretaceous-Paleocene subduction zone complex in southern California with a focus on large-scale infiltration of metamorphic fluids generated during shallow subduction into the Eastern Peninsular Ranges Mylonite Zone (Holk et al., 2006) and the generation of these fluids from the Catalina and other subduction-related schists, (3) a 1 billion year fluid evolution of sedimentary basins that host the world's largest uranium deposits (Holk et al., 2003), and (4) Archean submarine hydrothermal systems associated with felsic caldera systems that host massive sulfide deposits (Holk et al., 2008).

References
Holk, G.J., Kyser, T.K., Chipley, D., Hiatt, E.E., and Marlatt, J. (2003) Mobile trace elements and Pb-isotopes during late-stage evolution of Protrozoic sedimentary basins hosting uranium deposits. Journal of Exploration Geochemistry, v. 80, p. 297-320.
Holk, G.J., Taylor, H.P., and Gromet, L.P. (2006) Stable isotope evidence for large-scale infiltration of metamorphic fluids generated during shallow subduction into the Eastern Peninsular Ranges Mylonite Zone (EPRMZ), Southern California. International Geology Review, v. 48, p. 209-222.
Holk, G.J., Taylor, B.E., Galley, A.G. (2008) Oxygen isotope mapping of the Archean Sturgeon Lake caldera complex, Northwestern Ontario, Canada. Mineralium Deposita, v. 43, p. 623-640.
Holk, G.J., and Taylor, H.P. Jr. (2007) 18O/16O studies of regional metamorphism, anatexis, extensional magmatism, meteoric-hydrothermal activity, and ore deposition in the Valhalla metamorphic core complex, British Columbia. Economic Geology, v. 102, p. 1063-1078.

Thesis Defense - Fall 2008 - Steven Stuart

Groundwater and Surface Water Interactions at the Tijuana Estuary, San Diego County, California

Steven Stuart
M.S. Candidate
Department of Geological Sciences
San Diego State University
Advisor Kathy Thorbjarnarson

Monday, October 15th, 2008

ABSTRACT
The Tijuana Estuary is a unique coastal plain and wetland-dominated estuary influenced by tidal fluctuations and saltwater inflow from the Pacific Ocean and by intermittent freshwater inflow from the Tijuana River. The lower Tijuana River valley, the alluvial river valley that leads into the estuary, collects 96% of runoff in the 4,500 km2 Tijuana River watershed. Stream flow in the Tijuana River is ephemeral and regulated by precipitation events and dam releases upstream in the watershed. The quality of surface water is impacted by sewage discharges in Mexico and storm water runoff. Groundwater in the river valley flows west to the estuary and is impacted by local agricultural and sod farming activities. The purpose of this study was to evaluate the influence of groundwater and surface water from the lower Tijuana River valley on salinity levels in the estuary and to characterize the interaction between surface water and groundwater in the estuary in response to diurnal tidal fluctuations.
This study incorporated simultaneous monitoring of groundwater and surface water elevations and salinity in the lower Tijuana River valley and Tijuana Estuary over a period of 1.5 years. Seasonal variations in water levels and salinity were observed in the river valley and estuary; however, the estuary was influenced more by diurnal tidal fluctuations, high spring tides, major precipitation events, and surface water runoff. Groundwater and surface water salinity in the estuary was brackish to hypersaline. Hypersaline groundwater was measured in areas with low hydraulic conductivities that dictated slow infiltration rates and in areas that were inundated with ocean water during high spring tides. Hypersaline surface water was measured in estuarine channels that were temporarily disconnected to tidal flushing. Precipitation events dramatically affected salinity in surface water where salinity temporarily fell below brackish levels. In groundwater, precipitation events typically caused a short-term spike in salinity as the initial wetting front of infiltrating rainwater carried a higher concentration of dissolved salts from the shallow soil to the water table. Continued recharge by infiltrating rainwater gradually decreased salinity over a few days after the precipitation event.
These observations demonstrated that the Tijuana Estuary is a highly variable and dynamic environment that is greatly influenced by diurnal tidal fluctuations, particularly during high spring tides, and major precipitation events and subsequent storm water runoff. It appeared that seasonal variations observed in the lower Tijuana River valley did not influence the hydrologic nature of the estuary.

SEMINAR - Shuo Ma

A Physical Model for Widespread Near-Surface and Fault Zone Damage Induced by Earthquakes

Shuo Ma
Department of Geological Sciences
San Diego State University

Wednesday, October 15th, 2008

Seismic observations indicate that material velocities at shallow depths decrease over a large area after large earthquakes. The reductions are widespread, and occur at distances of up to several source dimensions. A persistent low-velocity fault zone has also been documented extensively from seismic and geodetic observations, in which the velocity drops further after large earthquakes. Dynamic stresses carried by seismic waves in the near surface or accompanying rupture at depth in the fault zone, are thought to create these velocity reductions by causing material damage. However, a rigorous physical interpretation as to why modest dynamic stresses can cause widespread near-surface damage, and why fault damage zones form, is lacking. By using a Drucker-Prager yielding criterion to simulate dynamic rupture propagation on a vertical strike-slip fault, I show that the widespread near-surface damage is caused by material yielding induced by seismic waves under the low confining pressure. Because the confining pressure increases with depth, materials yield more easily near the surface. The yielding zone at depth is narrowly confined near the fault, but its thickness broadens dramatically near the surface, forming a ‘flower-like’ damage zone, which is commonly observed in the geologic record. The fault zone damage at depth is induced by the large dynamic stress associated with the rupture front, while is induced by strong seismic waves ahead of the rupture front near the Earth’s surface. These results have important implications for the formation and evolution of fault zones, and possibly for the dynamic triggering of earthquakes as well.

SEMINAR - Chun-Ta Lai

Use of stable isotopes in studies of forest-atmosphere H2O and CO2 exchange

Chun-Ta Lai
Department of Biology
San Diego State University

Wednesday, October 8th, 2008

Stable oxygen (18O/16O) and hydrogen (2H/1H) isotopes at natural abundance levels are useful tracers for studying water and carbon cycles in terrestrial ecosystems. Atmospheric water vapor contains fewer amounts of heavier water isotopes (2H and 18O) relative to the source water. In the case of surface water loss via vegetation (transpiration), this preferential loss of lighter water isotopologues result in enriched 2H and 18O contents in leaf water. Meanwhile, CO2 that diffuses into leaf intercellular space and later out of stomata become labeled by this enriched 18O signature. Scientists have used this labile 18O signal in studies of global carbon cycles and paleoclimatic reconstruction. Improving our understanding of leaf water 18O enrichment allows for the development of better process-based models to investigate biosphere-atmosphere water and carbon dioxide exchange processes spanning from ecosystem to global scales. Discussions will be emphasized on how biotic and abiotic factors influence diurnal and vertical variations of 2H and 18O in leaf water and water vapor in forest air.